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An updated 2016 echocardiographic algorithm for diagnosing left ventricular (LV) diastolic dysfunction (DD) was recently proposed. We aimed to assess the reliability of the 2016 echocardiographic LVDD grading algorithm in predicting elevated LV filling pressure and clinical outcomes compared to the 2009 version.We retrospectively identified 460 consecutive patients without atrial fibrillation or significant mitral valve disease who underwent transthoracic echocardiography within 24 hours of elective heart catheterization. LV end-diastolic pressure (LVEDP) and the time constant of isovolumic pressure decay (Tau) were determined. The association between DD grading by 2009 LVDD Recommendations and 2016 Recommendations with hemodynamic parameters and all-cause mortality were compared.The 2009 LVDD Recommendations classified 55 patients (12%) as having normal, 132 (29%) as grade 1, 156 (34%) as grade 2, and 117 (25%) as grade 3 DD. Based on 2016 Recommendations, 177 patients (38%) were normal, 50 (11%) were indeterminate, 124 (27%) patients were grade 1, 75 (16%) were grade 2, 26 (6%) were grade 3 DD, and 8 (2%) were cannot determine. The 2016 Recommendations had superior discriminatory accuracy in predicting LVEDP (P.001) but were not superior in predicting Tau. During median follow-up of 416 days (interquartile range: 5 to 2004 days), 54 patients (12%) died. Significant DD by 2016 Recommendations was associated with higher risk of mortality (P=.039, subdistribution HR1.85 [95% CI, 1.03-3.33]) in multivariable competing risk regression.The grading algorithm proposed by the 2016 LV diastolic dysfunction Recommendations detects elevated LVEDP and poor prognosis better than the 2009 Recommendations.

Objective The current understanding of pulmonary hypertension (PH) due to left ventricular diseases does not distinguish heart failure (HF) with reduced ejection fraction (HFrEF) from HF and preserved ejection fraction (HFpEF), in terms of pulmonary hemodynamics. The value of pulmonary vascular compliance (PCa) and diastolic pulmonary gradient (DPG) as predictors of survival in either HF syndrome is controversial. The aims of our study were to compare the pulmonary hemodynamics in the two HF phenotypes, given similar values of pulmonary artery wedge pressure (PAWP), and to evaluate the impact of PCa and DPG on survival. Methods We retrospectively reviewed the charts of 168 PH-HFrEF and 86 PH-HFpEF patients. The independent association of PCa and DPG with prognosis was assessed by means of a Cox proportional hazard model. All cause survival was analyzed over an average follow-up period of 50 months. Results PH-HFpEF patients had a significantly higher DPG than PH-HFrEF patients (6.1 ± 7.1 vs 1.8 ± 4.5 mmHg, adjusted P = .025). PCa was similar in PH-HFpEF and PH-HFrEF. PCa was a significant predictor of survival, according to previously described preset cutoffs (2.15 mL/mmHg in HFrEF and 1.1 mL/mmHg in HFpEF) and based on a continuous scale; whereas DPG had no impact on survival in both patients groups. Conclusion Our findings suggest that for similar levels of PAWP, pulmonary circulation may be stiffer in patients with HFpEF-PH than patients with HFrEF-PH, leading to higher DPGs. Nonetheless, PCa rather than DPG emerged as the stronger predictor of survival in both left-sided PH phenotypes.

Introduction Changes in atrioventricular (AV) conduction and need for permanent pacemaker (PPM) are a recognized complication after open aortic valve replacement. We hypothesized that the need for PPM after CoreValve (Corevalve Inc, Irvine, CA) can be predicted with a combination of baseline variables. Methods In patients undergoing transcatheter aortic valve implantation, potential clinical, electrocardiographic and echocardiographic predictors of permanent pacing requirement were studied. Results Between January 2007 and March 2008, 34 patients with severe symptomatic aortic stenosis were recruited in a single center. Mean age was 84.4 years (SD 5.4, range 71-93). Of 34 cases paced at baseline, 3 (8.8%) were excluded from this analysis, as was the single periprocedural mortality. Of the remaining 30, 10 underwent permanent pacemaker implantation during the same admission (33.3%). PPM was for prolonged high-grade AV block in 4 cases, episodic high-grade AV block in 5, and sinus node disease in 1. Need for pacemaker was correlated to left axis deviation at baseline ( P = .004, r = 0.508) and left bundle-branch block with left axis deviation ( P = .002, r = 0.548). It was related to diastolic interventricular septal dimension on transthoracic echocardiography >17 mm ( P = .045, r = 0.39) and the baseline thickness of the native noncoronary cusp ( P = .002, r = 0.655). A susceptibility model was generated, and if at least one of (1) left bundle-branch block with left axis deviation, (2) interventricular septal dimension >17 mm, or (3) noncoronary cusp thickness >8 mm was present, the likelihood of PPM could be predicted with 75% sensitivity and 100% specificity and a receiver operating characteristic curve area of 0.93 ± 0.055 ( P Conclusions After transcatheter aortic valve implantation with CoreValve, permanent pacing was performed in around a third of patients and we present preliminary concepts towards a predictive model for this phenomenon.

Background The ASSENT-3 study examined the safety and efficacy of 3 alternative regimens for ST-elevation acute myocardial infarction: full-dose tenecteplase (TNK-tPA) plus enoxaparin; half-dose TNK-tPA plus unfractionated heparin plus abciximab; and full-dose TNK-tPA plus unfractionated heparin. Objective The aim of the study was to examine the resource and economic effects of the 3 regimens in ASSENT-3 using empirically collected data from the trial. Methods Cost estimates for each resource use component collected in ASSENT-3 were derived from Medicare reimbursement rates and from detailed billing data collected as part of a previous study. Costs of study drugs were estimated using average wholesale prices. All analyses were by intention to treat. Resource use and medical costs were examined first in the United States alone, and then in the entire cohort. Results Differences in costs across treatment arms were primarily due to differences in cost of study medication. Irrespective of source of cost weights, the least expensive alternative among the 3 treatment regimens was TNK-tPA and enoxaparin. Although not statistically significant, in 80% of 1000 bootstrap replications, the TNK-tPA enoxaparin arm was associated with 30-day cost savings relative to the unfractionated heparin arm. Conclusion The favorable clinical outcomes demonstrated for enoxaparin arm relative to the unfractionated heparin arm in ASSENT-3 were accompanied by a favorable distribution of costs and support the designation of this regimen as economically attractive by conventional benchmarks.

Background Therapy with either low-molecular-weight heparin (LMWH) or glycoprotein (GP) IIb/IIIa receptor antagonists is of benefit to patients with acute coronary syndromes (ACSs). However, algorithms that define how LMWH may be used in patients, proceeding from medical management to intervention and in conjunction with GP IIb/IIIa inhibitors, are lacking. The objectives of this task force were to formulate recommendations based on all available data for the use of LMWH, both with and without GP IIb/IIIa receptor antagonists, and to provide seamless integration of care during the transition from medical to interventional management. Methods and Results An international task force of 14 cardiologists with extensive experience in clinical trials was convened in New York in February 2001 to address issues related to the use of LMWH in patients with non-ST-elevation ACS. Evidence from randomized trials, observational studies, and other reports was discussed, and consensus recommendations were formulated. Conclusions Substantial evidence exists that patients receiving LMWH for an ACS can safely undergo cardiac catheterization and percutaneous coronary intervention. Concerns regarding the transition of these patients from the medical service to the cardiac catheterization laboratory should therefore not impede the upstream use of LMWH. Furthermore, LMWH and GP IIb/IIIa receptor antagonists can be used safely in combination, with no apparent increase in the risk of major bleeding. Consensus algorithms for therapy are presented. (Am Heart J 2002;144:615-24.)

Although conventional inotropic agents such as catecholamines increase myocardial oxygen consumption, a newly developed inotropic agent, a Ca2+ sensitizer, may be able to increase cardiac output with less myocardial oxygen consumption. By using right-side heart catheterization, we assessed the ratio of the increase in myocardial oxygen consumption per unit increase in cardiac output during beta-adrenergic receptor stimulation (dobutamine, n = 15), phosphodiesterase inhibition (E-1020, n = 10), and Ca2+ sensitization (MCI-154, n = 17) in patients with coronary artery disease. Dobutamine increased cardiac output and myocardial oxygen consumption. E-1020 increased cardiac output but did not change myocardial oxygen consumption. MCI-154 increased cardiac output and decreased myocardial oxygen consumption. The oxygen cost of increasing cardiac output with dobutamine and with E-1020 was different from that with dextran infusion (n = 18); in contrast, the oxygen cost with MCI-154 was significantly smaller. Thus a newly developed Ca2+ sensitizer, MCI-154, may be beneficial for the treatment of heart failure.

Background Pulmonary capillary wedge pressure (PCWP) is routinely used as an indirect measure of the left atrial pressure (LAP), although the accuracy of this estimate, especially under pathological hemodynamic conditions, remains controversial. Objectives The aim of this prospective study was to investigate the reliability of PCWP for the evaluation of LAP under different hemodynamic conditions. Methods Simultaneous left and right heart catheterization data of 117 patients with pure mitral stenosis, obtained before and immediately after percutaneous mitral comissurotomy, were analyzed. Results A strong correlation and agreement between PCWP and LAP measurements was demonstrated (correlation coefficient = 0.97, mean bias ± CI, 0.3 ± −3.7 to 4.2 mm Hg). Comparison of measurements performed within a 5-minute interval and those performed simultaneously revealed that simultaneous pressure acquisition yielded better agreement between the 2 methods (bias ± CI, 1.82 ± 1.98 mm Hg). In contrast to previous observations, the discrepancy between the 2 measures did not increase with elevated PCWP. Multiple regression analysis failed to identify hemodynamic confounders of the discrepancy between the 2 pressures. The ability of PCWP to distinguish between normal and elevated LAP (cutoff set at 12 and 15 mm Hg, respectively), as tested by receiver operating characteristics analysis, demonstrated a remarkably high diagnostic accuracy (area under the curve: 0.989 and 0.996, respectively). Conclusions Although the described limits of agreement may not allow the interchangeability of PCWP and LAP, especially at lower pressure ranges, our data support the clinical use of PCWP as a robust and accurate estimate of LAP.

The normal pattern of the myocardial sympathetic innervation was studied in 15 subjects using single photon emission computed tomography (SPECT) gamma scintigraphy with iodine 123-labeled meta-iodobenzylguanidine (I123MIBG). Seven young subjects (mean age 29.4 +/- 7.5 years SD) with supraventricular tachycardia and eight older patients (mean age 53.0 +/- 5.1 years SD) with normal coronary arteries at cardiac catheterization and normal thallium-201 scintigrams were studied. MIBG uptake in the hearts of six patients with complete cardiac denervation after orthotopic cardiac transplantation was also studied. MIBG scintigrams were reconstructed into bull's-eye target plots and divided into eight equal sectors. Within each sector, four areas representing the apical, two midventricular, and basal regions were defined. There was a reduction in counts in the older group of subjects with normal coronary anatomy (1218.2 +/- 198.4) as compared with younger subjects with supraventricular tachycardia (1124.4 +/- 317.6), (F = 15.0, df = 1, p < 0.001). The difference was lost after adjustment for age (p = 0.2) by means of analysis of covariance. There was a difference in counts within different sectors of the scan (F = 5.7, df = 7, p < 0.001), with lateral and anterior sectors having higher counts than septal and inferior sectors. There was no difference in the counts within areas of the scan (F = 0.04, df = 3, not significant [NS]) or different areas within the sectors (F = 1.1, df = 21, NS). A small diminution of counts (approximately 10%) in the 10 o'clock region of the bull's-eye target plot was observed in some scans.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous atenolol was given to 31 patients just before balloon mitral valvotomy to assess the hemodynamic efficacy and safety of β-blockade in mitral stenosis complicated by pulmonary hypertension. Hemodynamic response in patients with pulmonary resistance >600 dynes · sec · cm −5 (group 2, n = 17) was compared with those (group 1, n = 14) with a resistance below this value. In addition to a higher pulmonary arterial resistance (by design), patients in group 2 had a higher systemic resistance, lower cardiac index, and smaller mitral valve area compared with those in group 1. After atenolol infusion, transmitral gradient and left atrial pressure improved similarly. In spite of the decline in left atrial pressure, pulmonary vascular resistance increased in both groups, more in group 2 (847 ± 398 dynes · sec · cm −5 to 1135 ± 648 dynes · sec · cm −5 ) than in group 1 (291 ± 149 dynes · sec · cm −5 to 363 ± 200; p p = 0.027 for group effect by two-way analysis of variance). Cardiac index declined similarly from 2.77 ± 0.51 L/min/m 2 to 2.37 ± 0.37 L/min/m 2 in group 1 and from 2.33 ± 0.58 L/min/m 2 to 1.92 ± 0.54 L/min/m 2 in group 2. Systemic pressure tended to decline only in group 2 (mean aortic pressure, 89 ± 12 mm Hg to 89 ± 12 mm Hg in group 1 and 90 ± 9 mm Hg to 83 ± 12 mm Hg in group 2; p = 0.06 for group effect). Two patients in group 2 required fluids and cardioactive drugs for severe hypotension (aortic systolic pressures, 50 and 60 mm Hg) after atenolol doses of 10 and 1.5 mg, respectively; and in three other patients in group 2 (who received doses of 10, 10, and 6 mg), mean aortic pressure fell to −5 to 2455 ± 487 dynes · sec · cm −5 ) and in group 1 (1617 ± 349 dynes · sec · cm −5 to 1824 ± 414 dynes · sec · cm −5 ) an inappropriate decline in systemic resistance was observed in these five patients (2002 ± 444 dynes · sec · cm −5 to 1851 ± 530 dynes · sec · cm −5 ; p = 0.05 for group effect). The only baseline hemodynamic marker of a hypotensive response to atenolol was a higher right atrial pressure (> 10 mm Hg in three of five patients). Thus β-blockade given to patients with pulmonary hypertension and right heart failure complicating mitral stenosis may produce hypotension as a result of a reduction in cardiac output with an inappropriate fall in systemic vascular resistance.

Background The transseptal technique has been widely used for diagnostic and therapeutic left-sided heart catheterization. However, its differential immediate and late outcomes among patients with various valvular and arrhythmic diseases are not yet determined. Methods Beginning from 1993, all patients undergoing transseptal procedures were screened and categorized into diagnosis, arrhythmia, and valvuloplasty groups according to the purposes of the catheterization. Incidences of transseptum-related acute major events (cardiac perforation, embolic stroke, and bradyarrhythmia during the procedure) and late complications (residual atrial septal defect [ASD], embolic stroke, bradyarrhythmia, and death up to 18 months) were analyzed and compared between groups. Results From January 1993 to May 2003, a total of 176 patients underwent 184 transseptal procedures for diagnosis of valvular heart diseases (n = 8), catheter ablation of arrhythmogenic foci (n = 29), and mitral valvuloplasty (n = 147). The immediate outcome was similar among the 3 groups, with an overall acute complication incidence of 3.8%. At follow-up, the incidences of bradyarrhythmia, embolic stroke, and death were not different among the 3 groups. Patients undergoing valvuloplasty had a significantly higher prevalence of residual ASD, especially for those with more severe mitral stenosis and less valvuloplasty success. However, presence of ASD did not impose disadvantage over the 1.5-year prognosis. Conclusion Transseptal left-sided heart catheterization can be safely applied to patients with different categories of cardiac diseases with comparably good immediate and late outcomes. Although patients undergoing percutaneous valvuloplasty have a higher chance of permanent ASD creation, their prognosis is not influenced.

Clinical scenario A 65-year-old man with hypertension, diabetes, and chronic renal insufficiency comes to your clinic complaining of progressive angina with moderate exertion. On exercise electrocardiogram, he exercises for 2 minutes and develops 2 mm of ST-segment depression. He develops severe angina, which causes him to stop the test. You admit him for cardiac catheterization, and his baseline labs show a creatinine of 2.2 mg/dl. You wonder if there is a benefit to pretreatment with N-acetylcysteine (NAC) to limit his risk of developing contrast nephropathy. Literature search Combining heart catheterization and acetylcysteine in Medline, you find several small studies as well as the following meta-analysis: Birck R, Krzossok S, Markowetz F, Schnulle P, van der Woude FJ, Braun C. Acetylcysteine for prevention of contrast nephropathy: meta-analysis. Lancet 2003;362:598-603. Question Does the addition of NAC to intravenous (IV) saline hydration limit contrast nephropathy in patients with baseline renal insufficiency who are undergoing cardiac catheterization? Design The study was a meta-analysis of 7 randomized, controlled trials. The authors of the trial attempted to ensure the validity of their meta-analysis. They exhaustively searched relevant studies and identified 13 potential reports for inclusion. Six of these were subsequently excluded because they did not meet the authors' prespecified inclusion criteria, which ensured that included studies were prospective, randomized, controlled trials of patients with chronic renal insufficiency receiving intravascular contrast media. To be included, trials had to randomize patients to NAC versus placebo and had to examine development of acute renal failure as the primary end point. Thus, 7 trials were incorporated into the meta-analysis. Patients In total, 805 patients with chronic renal insufficiency in 7 trials of coronary angiography/percutaneous transluminal coronary angioplasty and 1 trial of computed tomography (CT) scan receiving IV contrast dye were studied. The amount of dye used in the studies varied somewhat, from 75 mL per patient in 1 study (patients undergoing CT scan with a fixed dose of dye) to a mean of 187 ml per patient in a trial in which most of the patients underwent interventional procedures. Intervention The intervention studied was oral NAC versus placebo given before contrast administration. NAC dosing regimens varied slightly in the trials. Five trials prescribed 600 mg of oral NAC given twice daily for 4 doses, another administered 400 mg twice daily for 4 doses, and 1 trial gave 1200 mg once before the procedure and once after. All trials used similar methods of periprocedural IV hydration. Main outcome measures The main outcome measures were as follows: incidence of contrast nephropathy at 48 hours, as defined by a rise in serum creatinine of at least 0.5 mg/dL in 4 trials, a serum creatinine rise of >25% in 2 trials, and either of the above measures in 1 trial. Main results Because a Q statistic suggested statistical heterogeneity (P =.016), a random effects model was used to analyze the data. The authors found a 56% relative risk reduction in the incidence of contrast nephropathy in patients who received periprocedural NAC (RR 0.44, 95% Cl 0.22-0.88). Meta-regression found that neither the volume of contrast administered nor the degree of chronic renal insufficiency was associated with the relative risk of contrast nephropathy.

In chronic heart failure (CHF) the contributing role of increased sympathetic activity and hemodynamic dysfunction in the genesis of ventricular arrhythmias has not been well established. To assess the relation between severe ventricular arrhythmias, hemodynamic impairment, and autonomic nervous system derangement, 142 patients with CHF in sinus rhythm underwent 24-hour electrocardiographic recording, right-sided heart catheterization, and evaluation of sympathovagal balance by heart rate variability (HRV) and baroreflex sensitivity (BRS). Patients were grouped according to the absence (without nonsustained ventricular tachycardia [NSVT]; n =87) or presence (with NSVT; n =55) of NSVT. Patients with NSVT had higher pulmonary artery and capillary pressures and more pronounced signs of sympathetic activation and parasympathetic withdrawal compared with those without NSVT. However, logistic regression analysis revealed that depressed BRS but not reduced HRV was significantly associated with the presence of NSVT, at both univariate analysis and after adjustment for clinical and hemodynamic variables. Moreover, it was found that when depressed BRS was associated with high pulmonary capillary pressure, the odds ratio for having NSVT rose markedly from 3.8 to 6.5. In conclusion, this study indicates that in stable CHF the assessment of arterial baroreflex function, but not HRV analysis, allows identification of patients at high risk of NSVT. It is suggested that the effect of depressed BRS is strengthened by the simultaneous presence of increased myocardial wall stress. These data support the hypothesis of a contributory role of autonomic nervous system dysfunction as expressed by the inability to activate effective vagal reflexes and an indirect index of ventricular stretch in the genesis of life-threatening arrhythmias.

Early recognition of heart failure is important because early treatment reduces mortality and hospitalization rates. In screening for this disease, there is a need for a simple, safe, and cost-effective method to obtain cardiovascular variables. Therefore we developed a noninvasive impedance cardiographic method to predict the pulmonary capillary wedge pressure (PCWP) from the impedance cardiogram. The impedance cardiographic technique, though, was originally designed for stroke volume (SV) determination. The objectives of this study were to validate both variables by comparison with the paired, invasively obtained equivalents. PCWP, measured with a pulmonary artery catheter, was related to the O/C ratio from the impedance cardiogram. The O/C ratio was calculated as the amplitude of the impedance cardiogram during diastole (O) divided by the maximum height during systole (C). Stroke volume was also calculated from the impedance cardiogram according to the equation of Kubicek (SVIC) and compared with thermodilution (SVTD). Data analysis was performed in 24 stable patients who underwent diagnostic heart catheterization. Linear regression analysis showed that the O/C ratio was strongly related to the invasively measured PCWP over a range of 3 to 30 mm Hg (r = 0.92, standard error of the estimate, 3.2 mm Hg). Between SVIC and SVTD a moderate correlation was established (r = 0.69), but after exclusion of the data from patients with an aortic valve disorder (n = 5), the correlation increased considerably (r = 0.87). No significant differences between SVIC and SVTD were found (mean difference +/- 2 SD = 1.8 +/- 28.8 ml). These preliminary observations suggest that impedance cardiography can predict PCWP and measure SV over a wide range of clinically relevant values. The combined measurement of SV and PCWP by impedance cardiography might be a clinical useful tool in screening for heart failure.

Evaluation of mitral regurgitation is difficult whether invasive or noninvasive methods are used. The determination of the regurgitant volume itself cannot be done in clinical practice with reasonable accuracy. In six sheep with chronic mitral regurgitation, left ventricular and left atrial pressures were recorded with high-fidelity catheters. The regurgitant volume was measured directly with electromagnetic flow probes positioned at the mitral annulus and around the ascending aorta, balanced against each other. A total of 24 hemodynamic states were obtained varying preload and afterload by fluid expansion and angiotensin infusion. On the basis of these studies, the pressure ratio of the V wave divided by the left ventricular systolic pressure is proposed as an index of regurgitant volume. A good correlation was found between this ratio and the regurgitant volume (r = 0.75). The ratio is easily recorded during routine heart catheterization.

Valve area and cardiac output were determined with magnetic resonance (MR) velocity mapping in 12 patients with aortic stenosis. Heart catheterization, Doppler echocardiography, and indicator dilution were performed for comparison. Left ventricle could be catheterized in only nine patients; in these cases, MR measured a mean valve area of 1.2 cm2 compared with 0.9 cm2 derived from catheterization data, with a mean difference of 0.2 cm2 between the 2 methods. The limits of agreement were [0.0, +0.5] cm2, less in patients with an important degree of concomitant regurgitation. In the whole material, MR measured a mean area of 1.1 cm2 compared with 1.2 cm2 derived from Doppler echocardiography data, with a mean difference of 0.1 cm2 and [-0.5, +0.6] cm2 as limits of agreement. In 11 patients the cardiac output was quantified by MR to a mean of 4.9 L/min and by indicator dilution to 5.0 L/min, with a mean difference of 0.2 L/min, and [-0.6, +0.8] L/min as limits of agreement. In addition, MR offers the major advance of simultaneous quantification of regurgitant volume in cases of concomitant regurgitation. In conclusion, because the two important prognostic determinants in aortic stenosis--the valvular area and the cardiac output--may be quantified, MR has potential to become a clinical tool in assessment of severity in aortic stenosis.

Over a 7-year period, 110 of 35,000 echocardiographic cases were diagnosed to have total anomalous pulmonary venous connection (TAPVC). Ages ranged from 7 days to 38 years (male 62, female, 48). In 60 cases the diagnosis was confirmed by angiography (n = 47) and/or surgery (n = 50). In 13 cases angiography was not performed; surgery was performed on the basis of echocardiographic diagnosis. Diagnosis of TAPVC was correctly made in all of the 60 confirmed cases. Drainage sites were correctly identified by echocardiography in 58 (96.7%) of these 60 cases. Of the five cases of mixed TAPVC, the second drainage site was missed by echocardiography in two cases. Of the 110 cases the drainage sites were as follows: supracardiac 70, cardiac 30, infracardiac 5, and mixed variety 5. Seventeen cases had Doppler echocardiographic evidence of obstruction along the course of the anomalous vein. The continuous wave Doppler signal for tricuspid regurgitation was present in 14 of 47 catheterized patients, and catheterization-measured peak pulmonary artery systolic pressure correlated well with that derived by Doppler study (r = 0.96, p = 0.001). Additionally, 17 patients had other cardiac anomalies that were correctly diagnosed by echocardiography. Combined two-dimensional and Doppler echocardiography is accurate in the diagnosis of TAPVC, identification of the site of drainage, presence of obstruction, and assessment of pulmonary arterial hypertension and other associated anomalies.

Many physicians assume that a reliable diagnosis of idiopathic dilated cardiomyopathy can be made by noninvasive methods, mainly echocardiography. On the other hand, use of endomyocardial biopsy in those patients who have undergone left heart catheterization and who demonstrate left ventricular dysfunction of unknown origin is increasing. Therefore the purpose of this study was to investigate the yield of that diagnostic strategy in patients with the tentative diagnosis of idiopathic dilated cardiomyopathy. Between 1980 and 1988, 3.2% of our 15,442 patients were diagnosed as having idiopathic dilated cardiomyopathy on the basis of left heart catheterizations and coronary angiograms. Idiopathic dilated cardiomyopathy was diagnosed in 444 patients on the basis of clinical data and results of noninvasive tests before catheterization, but in only 295 of these cases was the diagnosis confirmed by means of coronary angiography and left heart catheterization (predictive value of noninvasive tests is 66%). The remaining 34% of patients demonstrated extensive coronary artery disease (13%), significant valvular heart disease (11%), and other or no heart disease (10%). The diagnostic sensitivity of noninvasive tools (patient history, ECG, stress test, echocardiography) was only 59%. Left heart catheterization can easily be combined with endomyocardial biopsy. With the use of histologic techniques, specific heart muscle diseases were detectable in 3.5% of 209 patients, but in only 1% could therapeutic consequences be determined. Thus coronary angiography and left heart catheterization are mandatory for the correct diagnosis of idiopathic dilated cardiomyopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

For 29 patients with congestive heart failure (CHF), 24-hour noninvasive ambulatory blood pressure (ABP) and heart rate (HR) measurement profiles were described, using the periodogram method, and were compared with the same findings in 22 matched controls. Right-sided heart catheterization was performed in all patients. The mean cardiac index was 2.2 L/min/m2 (range 1.3 to 2.9 L/min/m2). More severe CHF, as assessed by cardiac index, pulmonary artery wedge pressure, and right atrial pressure, correlated significantly with a reduction in the amplitude of the circadian ABP and HR rhythms (0.38 less than r less than 0.63; p less than 0.05). Moreover, a reduced increase in cardiac index during cycloergometric exercise in 11 CHF patients correlated with a blunting of the circadian systolic ABP and HR profiles (0.57 less than r less than 0.90; p less than 0.05). Our results indicate that there is a reduction in the amplitude of the circadian BP and HR rhythms related to the severity of CHF.

Seventy-three patients with a CarboMedics aortic bileaflet valve prosthesis were examined by Doppler ultrasonography, and 27 of them were also assessed by transseptal catheterization. The ultrasonic mean systolic gradient was 17.1 +/- 5.6 mm Hg for valve size 19 mm, falling gradually with increasing valve size to 6.8 +/- 2.5 mm Hg for size 27 mm. The catheter mean systolic gradient was consistently smaller than the ultrasonic gradient (4.3 +/- 4.8 mm Hg), but Tobit regression analysis showed a significant association between the two methods. In all patients both methods revealed negligible to small amounts of retrograde leakage, which is assumed to be a normal finding for this valve. The effective flow areas of the valves calculated from the ultrasonic data were similar to the in vitro calculated flow areas. The hemodynamic potential of this valve is therefore completely utilized in vivo. The effective orifice area corrected for body surface area increased with increasing valve size, which demonstrates a moderate valve-patient mismatch.

To estimate the incidence of residual atrial septal perforation (ASP) following percutaneous transvenous mitral commissurotomy (PTMC) with the Inoue balloon catheter and to examine the factors contributing to ASP, we studied 46 patients with mitral stenosis undergoing PTMC. Residual ASP was evaluated by Doppler color flow imaging 1 day after PTMC, and was detected in 7 out of 46 patients (15.2%). We examined the relationship between the development of ASP (ASP+) and the age of the patient, the left atrial dimension before PTMC, the mean pressure difference between left and right atrium after PTMC, and the duration of the procedure from atrial septal puncture by the Brockenbrough method to balloon inflation. There was a good correlation between the development of residual ASP and the duration of the procedure (ASP+, 51.0 +/- 34.0 minutes; without ASP, 24.6 +/- 16.2 minutes; p less than 0.01). However, there was no significant correlation between the development of ASP and other factors. In the follow-up study, ASP disappeared in four patients within 3 months. ASP persisted in two patients for 1 year after PTMC. However, the shunt in these two patients was clinically insignificant. These data suggest that residual ASP may depend on the duration of the procedure, and that most cases of ASP disappear within 1 year after PTMC.

A case of tricuspid atresia with surgical intervention has been presented. The infant died after what appeared, clinically, to be an episode of acute hypoxia. At autopsy, the brain showed two very unusual lesions, massive necrosis of white matter and disseminated fungal granulomata. The evidence that the first of these is an anoxic lesion is reviewed. The second is considered to be a terminal event.

Plasma concentrations of atrial natriuretic peptide (ANP) after acute myocardial infarction were measured at fixed times during 48 hours in 38 patients admitted to the hospital within 4.4 hours after the onset of symptoms. Three hours after admission, the mean concentration of ANP was significantly lower than that at the time of admission. Thereafter it rose steadily until 15 hours after admission. ANP concentrations measured in each patient at the time of admission and the individual mean ANP concentrations during the first 48 hours after admission correlated weakly but significantly with the size of the infarct and the left ventricular function. Neither the site of the infarct, the occurrence of reperfusion, nor the number of coronary vessels affected influenced the ANP concentration. In 24 patients in whom cardiac catheterization was performed, no relationship between ANP concentrations and left ventricular pressures was observed. Determination of ANP concentrations seems to be of little value in assessing cardiac function after acute myocardial infarction.

A randomized trial of intracornary thrombolysis in a multicenter, geographically limited community has been undertaken. There have been no deaths or important morbidity because of heart catheterization. Preliminary data analysis has shown that patient entry within 3 hours of the onset of infarction has been the exception rather than the rule. It is anticipated that this trial will be completed by mid 1983. It is hoped that the data obtained from this study will help clarify the role of thrombolysis in acute myocardial infarction.

Summary Thirty-nine patients with a small ASD of the secundum type were followed clinically for 5 to 21 years (mean 11.6 years); no evidence of deterioration was found. In 26 of these cases recatheterization was carried out with a mean follow-up period of 9.8 years. No significant changes were found in most patients; in four patients, however, the leftto-right shunt had increased significantly. Our recommendations are that we will continue to advise surgery in patients with large ASD's, whereas we still do not recommend surgery in patients with small ASD's; the latter patients should be followed for longer periods to ensure that no deterioration occurs. The decision as to whether an ASD should be regarded as large or small in our opinion not only should be based on a chosen limit of pulmonary-to-systemic flow ratio, but clinical factors such as diastolic flow murmurs, ECG changes, the heart size, and the pulmonary vascular markings should also be taken into consideration.

Seventeen patients with chronic aortic regurgitation (AR) were examined by echocardiography and left and right heart catheterization. Cardiac output and regurgitation volume were measured by the dye dilution method. Administration of single and four repeated doses of prazosin (PZ) led to reductions of left ventricular (LV) end-diastolic, end-systolic, and left atrial end-systolic diameters, and decrease of left ventricular filling pressure. Regurgitation fraction, regurgitation flow, and volume indexes decreased significantly (p less than 0.01). Total left ventricular output decreased (p less than 0.001) as did derived parameters of left ventricular work and performance. Fractional shortening, ejection fraction, and mean circumferential fiber shortening velocity increased as did LV dP/dt and dP/dt/P. Changes in heart rate and cardiac and stroke indexes after PZ were not significant. Preload reduction (dilation of the venous bed and reduction of regurgitation) seems to be the most important effect of PZ in AR. We found PZ to be a suitable and effective drug for oral treatment of chronic AR.

We evaluated ultrafast CT as a method to measure left ventricular ejection fraction in 16 adults with congenital or acquired heart disease who underwent cardiac catheterization. CT scanning of the left ventricle was performed at 4 to 12 adjacent 1 cm levels (depending on heart size) at 50 msec/scan for one cardiac cycle, with the table positioned with an axial tilt of 10 to 20 degrees and a lateral slew of 5 to 10 degrees to best approximate the long axis of the left ventricle. Image enhancement was achieved by an injection of 25 ml of Renografin-76 via a peripheral vein, with scanning timed to coincide with maximal enhancement of the left ventricular cavity. Ejection fraction was computed by measuring the percent change in area of the left ventricle from diastole (largest area) to systole (smallest area) in a single slice at the mid-left ventricular level. Mean ejection fraction for the group was 58.1 +/- 15.1% (range 24% to 84%). The ejection fraction from left ventriculography, computed from biplane images using the Dodge (area-length) formula, was 59.6 +/- 12.3% (range 28% to 77%). There was an excellent correlation between left ventricular ejection fraction by CT and ventriculography (r = 0.91, y = 1.1x - 8.5, p less than 0.001). This study demonstrates that ultrafast CT can provide an accurate measure of left ventricular ejection fraction by simple methodology.

Little is known regarding the effects of propranolol (P) on sinus node function in children. In this study, corrected sinus node recovery time (CSNRT) and estimated sinoatrial conduction time (SACT) were measured in 10 children (ages 3 to 16 years; mean 8.3 years) without clinical evidence of sinus node dysfunction before and after intravenous P. The spontaneous sinus cycle length (SCL) increased after P(0.1 mg/kg) in all patients. Mean SCL increased 13.4% from 635 +/- 200 msec (+/- SD) to 720 +/- 202 msec (p less than 0.01). Maximum CSNRT increased in nine patients after P and mean CSNRT increased 63% from 203 +/- 61 msec to 330 +/- 190 msec (p less than 0.05). SACT changed in a random fashion after P. Mean SACT did not change significantly. We conclude that P significantly suppresses sinus node automaticity in children with normal sinus node function but has little or no effect on sinoatrial conduction.

Summary In 11 patients with nonobstructive cardiomyopathy and coronary heart disease and decreased myocardial function of the left ventricle, as well as in nine patients without left heart valvular or myocardial disease, left apexcardiograms were recorded during diagnostic heart valvular or myocardial disease, left apexcardiograms were recorded during diagnostic heart catheterization, wherein micromanometers were used; ACG's were registered additionally in 54 healthy volunteers in order to establish the normal range of apexcardiographic parameters. In all cases the apex tracings were recorded by means of a pulse transducer with infinite time constant. The most important finding of this study was the close correlation between the duration of the systolic upstroke (SUT) of the apex tracing and some accepted isovolumic indexes of left heart function (isovolumic contraction time, time interval from the onset to peak of the first derivative of left ventricular pressure, maximal value of the first derivative of left ventricular pressure, and the peak measured velocity of shortening of the contractile elements). Further, the mean value of SUT in patients with impaired left myocardial function was significantly prolonged, compared to the control subjects; an overlap was apparent due to the fact that some of these patients showed a normal left myocardial performance at rest, having an abnormal response only to exercise tests. The apexcardiographic SUT can practically always be measured when the first derivative of apex tracing is simultaneously recorded. It showed itself to be only slightly influenced by the resting heart rate. The mentioned relationship of the systolic upstroke time of the ACG to internal isovolumic indexes of myocardial function makes this noninvasive measurable parameter an additional excellent tool for the evaluation of the left myocardial state, thus supporting a new aspect of the value of quantitative apexcardiography.

Two patients with hereditary telangiectasia (Osler-Weber-Rendu disease) and high-output congestive heart failure secondary to large hepatic arteriovenous malformations had preoperative heart catheterization and exploratory cardiotomy to correct presumed intracardiac left-to-right shunts at the atrial level. At operation, both patients had oxygen-enriched blood returning from the inferior vena cava. Subsequent hepatic angiography demonstrated large hepatic arteriovenous fistulas, and both patients underwent hepatic artery banding and ligation, with reduction of left-to-right shunting.

This 14-year-old boy had an abnormal vascular connection which permitted a large right-to-left shunt, resulting in marked peripheral unsaturation, clubbing, and secondary polycythemia. Only recently had symptoms appeared, and with the exception of cyanosis and clubbing, his physical examination was normal. He had a normal electrocardiogram, and only in retrospect was an abnormality noted on the chest x-ray film. The feasibility of surgical repair was demonstrated by occluding the anomalous right pulmonary artery-left atrial communication with a balloon catheter. Surgical repair has been performed, with excellent results.

Coronary sinus rhythm was produced experimentally in 8 patients, utilizing the bipolar pacing catheter in the os of the coronary sinus. The distinction between coronary sinus rhythm and upper nodal rhythm is again seen to be an arbitrary one. The value of the P-R interval in coronary sinus rhythm and its relation to A-V block is discussed.

A 2-month-old male infant with severe pulmonary stenosis was found to have a myxoma of the pulmonary valve; the diagnosis was suggested by angiocardiography and confirmed by open-heart surgery. Previous reports indicate that myxomas of valvular origin are rare and asymptomatic, relative to mural myxomas.

1. 1. Clinical experience with the use of a bipolar catheter electrode pacemaker is reported in 7 patients with acute myocardial infarction complicated by Adams-Stokes attacks due to asystole or complete heart block. 2. 2. The use of a bipolar catheter electrode for 2 to 6 days resulted in spontaneous return of normal sinus rhythm in 6 patients, whereas another patient had a permanent pacemaker implanted surgically 6 weeks later. 3. 3. Mortality was reduced to 14 per cent; the one fatality occurred in the single patient who was catheterized twice, but who died unexpectedly on the thirteenth day. Survivors have returned to work after recovery from infarction. 4. 4. Problems in management, especially with unstable cardiac mechanisms and conduction during a transition period in recovery, have been cited.

The frequency of complications in a material consisting of 4,413 catheterizations of the right side of the heart performed in the same laboratory over 16 years is reported. The patient material consisted mainly of adults and older children. Two thirds of the patients had a congenital heart disease, and one third had an acquired heart disease. Two deaths occurred in direct connection with the examination (0.045 per cent). During the days which followed the examination, 3 severely ill patients died, but there was no reason to assume that these deaths were caused by the examination. Apart from single extrasystoles, arrhythmia occurred in 135 cases (3 per cent). The arrhythmia was considered to be perilous in 4 cases (0.09 per cent): 2 cases of severe arrhythmia were ventricular tachycardia, one of which had a fatal outcome. The other 2 cases were ventricular fibrillation; both patients survived after cardiac massage and A.C. defibrillation, but one of them died 10 days later. Lesions of the heart produced by the catheter occurred twice; in both cases the heart wall was perforated and the course was benign. The risk of death or late sequelae in connection with heart catheterization is slight. Dangerous complications may arise, however, and heart catheterization should, therefore, be performed only when there is access to treatment with electrical stimulation of the heart and to assistance from chest surgeons.

The electrocardiographic variations registered by endocardiac catheterization in man are described on the basis of twenty-three cases studied. The tracings show mainly the variations of potential of the heart, detected at the endocardiac surface. Endocardiac leads can be considered to be direct leads. The tracings are endocardiac electrograms. The auricular endocardiac electrogram (endocardiac P wave) consist normally of a series of rapid deflections (S, e, i, o waves) joined to a final slow deflection (Ta wave) by means of the o−u segment. The shape of the auricular electroendogram undergoes modifications according to the position of the electrode inside the auricle. Rapid deflections represent the process of depolarization of the auricles. Repolarization is represented by the final slow portion, as in the ventricular complex. The initial negative deflection (S wave) of the auricular complex is regarded as an exponent of the activity of the sino-auricular node. The endocardiac ventricular electrogram undergoes modifications in shape, depending upon whether the electrode is placed in the right ventricle or right auricle. The electroendogram obtained from the ventricle (type I) shows an initial positive deviation (R wave) produced by the excitation of the interventricular septum which is followed by a negative deflection of large amplitude (S wave) and a large negative T wave. The waves of depolarization and of repolarization of the ventricular wall (R waves and T waves) have, then, the same direction. The positive deviation of the S-T segment is greater as the catheter approaches nearer the septum. The ventricular electroendogram recorded from inside the auricle (type II) traces the negative potentials of the ventricular activity during the spreading of the excitation wave. It begins with a negative deflection (Q or QS wave) followed by a positive deviation, an inconstant element, and ends in a T wave which is usually negative, sharply pointed, and deep. The ventricular complex of this type of tracing is similar to the ventricular complex of the esophageal electrocardiogram obtained when the catheter is at the level of the auricle. The variations of endocardiac potential in bundle branch block, in one case of auricular extrasystoles, in one case of auricular asynchronism, and in cases of premature contractions of the right and left ventricles are described. The electrocardiographic curves registered with the catheter placed in the superior and inferior venae cavae and at different sites in the venous system are described. In bundle branch block of the common type, the endocardiac electrogram taken from inside the ventricle shows the absence of the initial positive (R) wave as a result of the abnormal excitation of the interventricular septum which is accomplished from right to left. The right ventricular cavity remains negative during the inscription of QRS complex. In bundle branch block of the uncommon type the right ventricular cavity is initially positive. In the cases of bundle branch block which were studied the endocardiac electrogram shows the same characteristics that have been observed in experimental bundle branch block in the dog.

In order to study the modifying effects due to transmission of sounds through the structures of the chest and to calibrate cardiovascular sounds at the source, single-frequency sounds (from 25 to 10,000 c.p.s.) and multifrequency sounds (such as the human voice, sounds of muscial instruments, externally recorded heart sounds and murmurs) were delivered into the heart by means of a specially designed cardiac catheter: the vibrocatheter. The sounds were then recorded externally from the four areas of auscultation. The results show that the attenuation of cardiovascular sounds depends upon: (1) the site of production and the frequency components of sounds, and (2) the characteristics of the conducting tissues. Illustrative examples of the attenuation of sounds delivered into the cavities of the right side of the heart and the pulmonary artery are given. The vibrocatheter is effective not only in delivering signals of known parameters into the heart, but also in collecting intracardiac sounds and transmitting them outside the body simultaneously with an intracardiac pressure curve. In this respect it allows direct intracardiac auscultation and represents a simple and promising means for a new technique of intracardiac phonocardiography.

The volume of blood in the vascular bed of the lungs can be estimated, by the Stewart-Hamilton principle, as the product of cardiac output and pulmonary mean transit time. Previous investigators have measured this time indirectly as the difference between transit times from the pulmonary artery and the left atrium to a peripheral artery. The present study was an investigation of the feasibility of measurement of pulmonary blood volume by the simpler and more direct approach of sampling a single dilution curve from the left atrium after injection of indicator into the pulmonary artery. Fifteen measurements were obtained in 10 patients with valvular heart disease. In all cases the atrial dilution curves exhibited satisfactory contours and presented no difficulties in discernment of a single discrete segment of exponential decay. There was an excellent correlation (r = +0.98) between cardiac outputs measured from atrial curves and those measured from simultaneous aortic or arterial dilution curves. Pulmonary blood volumes ranged from 236 to 403 ml./M. 2 , with a mean of 311 ml./M. 2 , representing 11 per cent of estimated total blood volume. This value differs insignificantly from the results obtained by others who used indirect measurements of pulmonary artery-to-left atrium transit time, but is appreciably smaller than earlier estimates of "central" or "intrathoracic" blood volume obtained from single arterial dilution curves or from isotopic techniques with precordial counting. Reproducibility was excellent: the largest scatter around the mean of a pair of measurements of pulmonary blood volume was ±8 ml./M. 2 . There was a significant correlation (r = + 0.73, p It is concluded: (1) that dilution curves sampled from the left atrium after injection of indicator into the pulmonary artery provide valid measurements of cardiac output and permit reproducible estimates of pulmonary blood volume, and (2) that the volume of blood in the vascular bed of the lungs is quite constant in the resting steady state, amounts to approximately 11 per cent of total blood volume, and may play a role in the regulation of stroke volume.

An analysis of 11 cases of total anomalous pulmonary venous connection indicates that the electro-vectorcardiogram consistently shows right axis deviation, right ventricular hypertrophy, and right atrial hypertrophy. The degree of elevation of right ventricular pressure may be correlated with certain electro-vectorcardiographic, hemodynamic, and anatomic observations.

A case report of a 29-year-old woman with increasing cardiac distress is reported. No murmur could be heard. The heart was not enlarged, but a prominent second left arch and pulmonary congestion were found on the roentgenogram. Moreover, the lower lobe of the left lung was markedly emphysematous. An electrocardiogram showed right ventricular hypertrophy. On heart catheterization, an excessive pulmonary hypertension was found, and the pulmonary “capillary pressure”, too, was very high. A mitral disease, therefore, was suggested, and the patient submitted to surgery. Thoracotomy revealed a normal mitral valve, and a normal pressure in the left atrium was measured directly. At post mortem the findings were fully explained, as a transverse septum with only one small perforation was separating the opening of the pulmonary veins from the rest of the atrium (so-called cor triatriatum). A review is made of the literature concerning anomalous, congenital structures within the left atrium. Thin cords or even broad bands across the lumen have been of no significance. The real cor triatriatum, however, was a serious disorder. Many of the patients died shortly after birth, and only a few reached the adult age. The clinical symptoms and signs were by no means characteristic, and no help was obtained from the usually employed investigations. An in-vivo diagnosis, therefore, must certainly be left for an explorative thoracotomy. The possibility of an effective surgical treatment is briefly discussed.

The weight of the right ventricle expressed as a per cent of the total myocardial weight (RVT × 100) was related to right ventricular pressure in the neonatal puppy. It was shown that during the first 4 weeks of life the regression curves of the right ventricular pressure and RVT were strikingly similar, thus establishing this quantitative postmortem measurement as a sensitive indicator of right ventricular pressure.

Three cases of cor triatriatum are reported. Each patient presented with breathlessness and had signs of pulmonary hypertension, with electrocardiographic evidence of right ventricular overload. Plain radiographs of the chest showed moderate left atrial enlargement and changes indicative of pulmonary venous engorgement. Left atrial enlargement was confirmed in 2 cases by angiocardiography and was quantitated by measurement of the left atrial volumes. Hemodynamic studies revealed a considerable increase in the pulmonary arterial pressure (78 mm. Hg systolic and 32 mm. Hg diastolic to 125 mm. Hg systolic and 75 mm. Hg diastolic) and in the “wedge” pressure (28 mm. Hg systolic and 20 mm. Hg diastolic to 65 mm. Hg systolic and 18 mm. Hg diastolic), with normal left ventricular end-diastolic pressures. Angiocardiography was performed in 2 patients, and in each the intra-atrial diaphragm was clearly demonstrated. Removal of the left atrial diaphragm was successful in 2 patients. The third patient, who had severe pulmonary vascular disease, died on the first postoperative day.

A case of systemic amyloidosis and plasmacytosis is presented. Both on clinical observation and cardiac catheterization, the features of this case simulated those of constrictive pericarditis. The pertinent literature is reviewed.

Clinical and autopsy findings are discussed in 9 patients in whom a diagnosis of “primary” pulmonary hypertension was made. In 6 of these cases, pulmonary emboli and thrombi provided the etiological basis for pulmonary hypertension. The difficulty of differentiating cases of recurrent pulmonary embolization from cases of “primary” pulmonary hypertension is discussed. The possibility that all cases of primary pulmonary hypertension represent recurrent embolization is considered. Therapy with anticoagulation and venous ligation is recommended for all cases of “primary” pulmonary hypertension.

Right atrial pressures were measured in 22 patients before and immediately after the cessation of airway straining. In 9 patients (Group I) who showed a normal response of the peripheral arterial blood pressure to the Valsalva maneuver, the resting mean right atrial pressure of 6.72.7mm. Hg rose to a mean of 12.27.6mm. Hg (p = 0.1) and differed significantly from that of Group I (p = Infusion of l-norepinephrine (4 micrograms per minute) into the right atrium of the 9 patients of Group I led to the emergence of the square wave response to the Valsalva maneuver within approximately 10 minutes of the infusion and subsquent to the maximum elevation in peripheral arterial blood pressure. The resting mean right atrial pressure rose significantly from 6.72.7to15.810.3mm. Hg (p = 0.1). No statistical difference obtained between the resting mean right atrial pressures of patients who showed the square wave response (Group II) and those of the patients who received infusion of l-norepinephrine (p = > 0.1), and it is suggested that an elevated central venous and right atrial mean pressure of approximately 13 mm. Hg in the presence of an increment of intrathoracic pressure not exceeding 40 mm. Hg becomes associated with the square wave phenomenon.

The circulatory and ventilatory responses to postprandial exercise were studied in normal men and compared with the fasting responses. The findings were as follows: (1) Exercising cardiac output was not affected by the meal. (2) The heart rate was faster during postprandial exercise. (3) The duration of systolic ejection was decreased out of proportion to the faster rate after the meal. (4) No significant change in arterial pO 2 , pH, or O 2 uptake was found in postprandial exercise when compared with fasting exercise. (5) The lactate-pyruvate ratio was significantly increased during exercise after a meal. It is concluded that the changes found can be best explained by a postprandial decrease in effective blood volume, an increase in myocardial inotropic state, and an alteration in the distribution of cardiac output.