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The determinants of the aortic regurgitant velocity profile have been investigated using computer and in vitro simulations in which regurgitant orifice area, ventricular and aortic compliance, and systemic vascular resistance could be independently varied. In the study, regurgitant fraction was altered, either by changing the size of the regurgitant orifice or by holding the regurgitant orifice constant and changing chamber compliance or systemic vascular resistance. Upon increasing regurgitant fraction by increasing the size of the regurgitant orifice, the slope got steeper and the pressure half-time shortened, the response anticipated in current clinical practice. However, when the regurgitant orifice was kept constant and regurgitation fraction was increased by increasing the systemic vascular resistance or by increasing the compliance of the left ventricle, slope became less steep and pressure half-time lengthened. Multivariate analysis was used to quantify the relationship of regurgitant fraction to slope and pressure half-time. When orifice area was allowed to vary, slope was related directly (multiple r = 0.78, p less than 0.001) and half-time was related inversely (multiple r = 0.66, p less than 0.001) to regurgitant fraction. With the orifice area fixed, however, directionally opposite responses were seen; slope varied inversely (multiple r = 0.87, p less than 0.001), whereas half-time varied directly (multiple r = 0.88, p less than 0.001) with regurgitant fraction. This study suggests that the utility of the slope and pressure half-time of the regurgitant velocity tracing in clinical practice relates to their ability to discriminate regurgitant orifices of differing sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

The diagnostic value of exercise echocardiography has been widely reported. In up to 20% of patients conventional transthoracic exercise echocardiography however is impossible due to impaired image quality related to exercise. In addition some patients will not be able to perform a conventional bicycle exercise test due to joint disease or peripheral vascular disease or a sufficient stress is not possible because of lack of patient motivation. In an attempt to overcome these limitations, a system has been developed which combines transesophageal echocardiography with simultaneous transesophageal atrial pacing via the same probe. Three circular silver pacing electrodes were installed at a distance of 7,9 and 12 cm from the tip of the echoscope. Square wave pulses of 10 ms and an intensity of 7 to 20 mA were delivered. After baseline recording at the patient's spontaneous heart rate, atrial pacing was initiated at a rate of 100 beats/min and increased stepwise every 2 min by 20 beats/min up to 85% of the age-predicted maximal heart rate. Pacing endpoints were designated to be the development of angina pectoris or dyspnea, persisting horizontal or downsloping ST-segment depression (0.2 mV 80 ms after the J-point in the 12-lead ECG) or the development of new segmental wall motion abnormalities. In a group of 50 patients with suspected coronary artery disease, coronary artery disease (luminal narrowing of more than 70% of at least one major vessel) was detected with high sensitivity (greater than 93%) and specificity (greater than 100%).(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular filling (as assessed by Doppler echocardiography) has previously been shown to depend in a complex fashion on ventricular diastolic function (compliance and relaxation) as well as other variables, such as atrial pressure and compliance, ventricular systolic function and mitral valve impedance. To study the effect of isolated physiologic alterations on individual Doppler indexes, a mathematic model of mitral flow was analyzed. By varying one physiologic variable at a time, it was shown that mitral velocity acceleration is affected directly by atrial pressure and inversely by the ventricular relaxation time constant, with relatively little impact of chamber compliance. Deceleration rate was directly influenced by mitral valve area, atrial pressure and ventricular systolic dysfunction and inversely affected by atrial and ventricular compliance relations, with little impact of relaxation unless it was so delayed as to be incomplete during deceleration. Peak velocity was directly affected most strongly by initial left atrial pressure, and lowered somewhat by prolonged relaxation, low atrial and ventricular compliance and systolic dysfunction. Strikingly different filling patterns emerged when the primary physiologic alterations were accompanied by simultaneous compensatory changes in atrial pressure designed to maintain stroke volume constant. Low ventricular compliance with preload compensation produced characteristic E waves with very short acceleration and deceleration times and high peak velocity. Thus, mathematic analysis of ventricular filling helps to explain the physical and physiologic basis for the transmitral velocity curve.

Mitral valve areas determined by Doppler pressure half-time were compared with areas obtained by planimetry in two groups of patients with mitral stenosis: 24 patients without aortic regurgitation and 32 patients with more than grade 1 aortic regurgitation. The severity of aortic regurgitation was assessed by color flow mapping; 17 patients had grade 2, 10 had grade 3 and 5 had grade 4 aortic regurgitation. Regression equations for pressure half-time area versus planimetry mitral valve area were calculated separately for the aortic regurgitation (r = 0.88) and the nonaortic regurgitation group (r = 0.86); analysis of covariance revealed a significant (p less than 0.001) difference between the two groups leading to overestimation of planimetry area by the pressure half-time method in the aortic regurgitation group. The mitral valve areas in the group without regurgitation were best calculated with the expression 239/T1/2 (r = 0.77) as compared with a best fit of 195/T1/2 (r = 0.85) for the aortic regurgitation group. To elucidate the mechanisms affecting pressure half-time in aortic regurgitation, an in vitro model of mitral inflow in the presence of varying regurgitant volumes and different ventricular chamber compliances was used. Aortic regurgitation shortened directly measured pressure half-time proportional to the regurgitant fraction but an increase in left ventricular compliance could offset this effect. Finally, in a mathematic model of mitral inflow the competing effects of aortic regurgitation and chamber compliance could be confirmed. In conclusion, aortic regurgitation results clinically in a significant net shortening of pressure half-time leading to mitral valve area overestimation. However, the effect is moderate and individually unpredictable because of changes in chamber compliance.

Fluid dynamics suggests that orifice geometry is a determinant of discharge properties and, therefore, should influence empiric constants in formulas (such as the Gorlin formula) to calculate stenotic valve area. An in vitro study utilizing a model of transmitral flow was conducted to investigate how the discharge coefficient changes with 1) orifice eccentricity (ratio of long to short diameter), 2) absolute area, 3) the presence of a nozzle-like inlet, and 4) varying flow. Twenty-three orifices with areas varying between 0.3 and 2.5 cm2 and eccentricities from 1:1, or circular, to 5:1, or elliptic, were tested. The calculated discharge coefficients ranged between 0.675 and 0.93. For a given area, the discharge coefficient decreased by a mean value (+/- SD) of 5.5 +/- 1.3% between circular orifices and 5:1 ellipses. Discharge coefficients increased by a mean of 8.9 +/- 3.5% from 0.3 to 2.5 cm2 area within each eccentricity class. A gradually tapering inlet (nozzle) raised the discharge coefficient by 8.8 +/- 3.9%, leading to a discharge coefficient between 0.81 and 0.93 for round orifices. The discharge coefficient did not change appreciably with flow. The concept of the discharge coefficient and its role in assessing restrictive orifices in general by hydraulic formulas (for example, the Gorlin and pressure half-time calculations) are discussed.

Previous investigations have shown that the size of a regurgitant jet as assessed by color Doppler flow mapping is independently affected by the flow rate and velocity (or driving pressure) of the jet. Fluid dynamics theory predicts that jet momentum (given by the orifice flow rate multiplied by velocity) should best predict the appearance of the jet in the receiving chamber and also that this momentum should remain constant throughout the jet. To test this hypothesis, we measured jet area versus driving pressure, flow rate, velocity, orifice area, and momentum and showed that momentum is the optimal jet parameter: jet area = 1.25 (momentum).28, r = 0.989, p less than 0.0001. However, the very curvilinear nature of this function indicated that chamber constraint strongly affected jet area, which limited the ability to predict jet momentum from observed jet area. To circumvent this limitation, we analyzed the velocities per se within the Doppler flow map. For jets formed by 1-81-mm Hg driving pressure through 0.005-0.5-cm2 orifices, the velocity distribution confirmed the fluid dynamic prediction: Gaussian (bell-shaped) profiles across the jet at each level with the centerline velocity decaying inversely with distance from the orifice. Furthermore, momentum was calculated directly from the flow maps, which was relatively constant within the jet and in good agreement with the known jet momentum at the orifice (r = 0.99). Finally, the measured momentum was divided by orifice velocity to yield an accurate estimate of the orifice flow rate (r = 0.99). Momentum was also divided by the square of velocity to yield effective orifice area (r = 0.84). We conclude that momentum is the single jet parameter that best predicts the color area displayed by Doppler flow mapping. Momentum can be measured directly from the velocities within the flow map, and when combined with orifice velocity, momentum provides an accurate estimate of flow rate and orifice area.

To study the long-term results of tricuspid valvuloplasty, pre- and postoperative (51 +/- 17 months) echocardiographic and catheterization data were collected from 51 patients (aged 59 +/- 9 years). Because of severe mitral stenosis all patients received a heterograft in the mitral position and underwent reconstructive tricuspid surgery with Carpentier rings. With regard to postoperative clinical outcome three patient groups were distinguished: 37 patients (group A) showed clear clinical improvement; in seven patients mild, and in three patients moderate tricuspid regurgitation persisted. A mild tricuspid stenosis of less than 4 mm Hg mean diastolic gradient was found in 11 patients. Patients in group B (n = 8) showed no clinical improvement, but there was persistence of moderate tricuspid regurgitation associated with nearly unchanged pulmonary hypertension in five patients and moderate tricuspid stenosis in two. Six patients (group C) showed deterioration of their clinical status; in two patients a severe degree of tricuspid regurgitation persisted, and four patients were first seen with a tricuspid stenosis with a mean diastolic gradient greater than 7 mm Hg. Analysis of postoperative data showed that tricuspid stenosis may develop during surgery in patients with slightly shrunken valve leaflets. Although the area of the anterior tricuspid leaflet was slightly underestimated, we found that long-term results of tricuspid valve annuloplasty with a Carpentier ring were encouraging. Doppler echocardiography for detection of tricuspid regurgitation and transvalvular pressure gradient showed results identical to hemodynamic data and is a suitable and sensitive method for evaluating postoperative results after tricuspid valve annuloplasty.

Until now, right atrial (RA) volume calculation by means of two-dimensional echocardiography (2-DE) has only been attempted in a single plane: the apical four-chamber view. Our study reports a new method for RA volume calculation using two intersecting 2-DE views. For this purpose, silicone rubber casts of 19 human necropsy hearts were obtained and thin-walled natural rubber moulds of the RA casts were prepared. Totally filled with and immersed in water, the moulds could be visualized in the apical four-chamber view and an additional 2-DE plane, the latter corresponding to the subcostal view in vivo. In this view the vertical extension of RA could be estimated. Areas and lengths of RA were determined in the respective planes, and RA volume was calculated by applying the formula, area x length, to two intersecting planes. Finally, volume of the silicone casts was determined angiocardiographically (Angio) using a biplane method (30 degrees RAO, 40 degrees LAO-40 degrees hepatoclavicular). The true RA volume was 106 +/- 23 ml (mean +/- 1 SD) as determined by water displacement. Using Angio an excellent correlation was found: the calculated volume amounted to 106 +/- 23 ml; the difference was 5.5 +/- 4.8 ml (n.s.); Angio vol = 0.93 true vol + 7.77; r = 0.95; SEE = 7.4 ml. Volume determination from the apical four-chamber view of 2-DE using a monoplane disk method resulted in a mean volume of 62 +/- 17 ml. The mean difference to the true RA volume was 44 +/- 16 ml (p less than 0.001). When volume calculations were made using the biplane method, a value of 105 +/- 22 ml resulted. The mean difference to true volumes was 7.4 +/- 4.8 ml: y = 0.84x + 15.88; r = 0.91; SEE = 9.4 ml. In an in vivo study endsystolic RA volumes were calculated in a normal adult population (n = 40) from the same intersecting planes as in vitro. A normal value of 38 +/- 6 ml/m2 was found. In vivo validation using Angio showed a slightly higher normal value of 43 = 7 ml/m2. Thus, 2-DE is highly accurate in determining RA volume. In the in vitro as well as in the in vivo study the results of monoplane calculations are clearly inferior to a method which also takes account of the vertical extension of RA.

Infusion of substance P into the renal artery was previously shown to cause a significant natriuresis which was associated with increased kallikrein excretion. Since the renal kinin and prostaglandin (PG) systems may be interrelated, the present study was performed to investigate the effects of substance P on renal function and its potential interaction with the renal PG system in the conscious rat. 24 female Sprague-Dawley rats were infused intravenously with substance P (1 ng . min-1 . kg-1 body weight) and the body weight was kept constant by an intravenous infusion of 0.45% saline. Substance P had no effects on arterial blood pressure, glomerular filtration rate (GFR) and 125I-hippuran clearance in the absence or presence of indomethacin (INDO). Basal UPGE2 V was unaltered by substance P infusion but was suppressed by INDO before and during substance P by 80 and 88%, respectively. Substance P raised urinary flow rate (V) by 105%, CH2O by 96%, UNaV by 378%, UKV by 48% and UPO4V by 147% (p less than 0.001). Although INDO significantly suppressed V, CH2O, and UNaV during all collection periods, it did not affect absolute UPO4V and UKV and the relative rise in V, CH2O, and UNaV induced by substance P. Thus, the diuretic and natriuretic effects of substance P are not mediated by renal PG, but are partially blunted by INDO through increased distal absorption of sodium and water, INDO has no effect on substance P-induced alterations in proximal tubular function.

Unlabelled: Between 1976 and 1984, 182 patients over 60 years with valvular defects were examined invasively and valve replacement was performed. 34 patients (19%) were older than 70 years. Hospital mortality was 2% in aortic valve replacement, 4% in mitral valve and 8% in double valve replacement. Overall early mortality in patients between 60 and 70 years of age was 3.4% and 6% in patients over 70 years for all operations. Simultaneous aortocoronary bypass surgery did not enhance the operation risk. During the follow-up period of 23 +/- 22 months a total of 21 patients died (12%). Only 4% of the survivals showed clinical deterioration by at least one NYHA class. Clinical tendency to improvement was as clearly evident among the patients of over 70 years of age as among the entire group. Preoperative invasive and noninvasive data do not display any significant correlation with the result of surgery. Significantly higher (P less than 0.05) mortality rates or inferior functional operation results were seen only with higher age, a preceding valve operation, and preoperative NYHA class IV., Conclusion: In elderly patients indication for valve replacement should not be more restrictive than in younger ones. Postponement of valve replacement in these age groups until the patient experiences symptoms when at rest (NYHA class IV) will adversely affect the chances of success and increase the mortality risk.

The right atrial (RA) volume can be determined angiographically from two perpendicular projections. Up to now volume calculations by means of two-dimensional echocardiography (2-DE) have only been attempted in a single plane, the apical four-chamber view. Our study reports a new method for RA volume calculation using two intersecting cross-sectional echocardiographic views. For this purpose silicone rubber casts of 20 human necropsy hearts were obtained and thin walled natural rubber moulds of the RA casts were prepared. Totally filled with and immersed in water, the mouls could be visualized in the apical four-chamber view and an additional echocardiographic plane, the latter corresponding to the subcostal view in vivo. In this view the vertical extension of RA could be estimated. Areas and length of RA were determined in the respective planes and RA volume was calculated by applying the formula: - Area X Length - to two intersecting planes. Finally, the latex moulds were filled with diluted contrast agent and the volume was determined angiographically using a biplane disc method. Real volume of RA was 112 +/- 23 ml (mean +/- 1 SD). Angiographically, an overestimation resulted: the calculated volume amounted to 119 +/- 24 ml, the mean difference was 7 +/- 2 ml (p less than 0.001). The regression equation was y = 1.04 X + 2.34, r = 0.995, SEE = 2.3 ml. Volume determination from the apical four-chamber view using a monoplane disc method resulted in a mean volume of 62 +/- 17 ml. The mean difference to the real RA volume was 50 +/- 17 ml, p less than 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)

To study the long-term results of tricuspid valvuloplasty, pre- and postoperatively (39 +/- 11 months), echocardiographic and catheterization data were collected in 37 patients (mean age, 58 +/- 8 years). Because of severe mitral stenosis, all patients received a porcine heterograft in the mitral position and underwent reconstructive tricuspid surgery with Carpentier rings (#32, n = 12; #34, n = 15; #36, n = 10). Sizing was performed by measuring the anterior leaflet area using an obturator. In nine patients, tricuspid leaflets were slightly shrunken at the insertion site of the chordae tendineae. Postoperative echocardiography and right heart catheterization were performed with simultaneous pressure recordings in the right ventricle and right atrium. A significant clinical improvement was noted in 24 patients, and this correlated with significant hemodynamic improvement. In eight patients, no clinical improvement was observed. Patients were divided into subgroups according to echocardiographic and hemodynamic criteria. Group A (n = 17) was composed of patients with significant improvement of hemodynamics, without detectable tricuspid valve dysfunction. Group B (n = 11) was composed of patients with slight-to-moderate tricuspid incompetence, detected by contrast echocardiography. In nine of these patients, the size of the RA and the diameter of the IVC were significantly smaller than preoperatively. In patients of Group C, echocardiography and catheterization data showed a slight-to-moderate tricuspid stenosis with a mean diastolic pressure gradient of 3.9 +/- 1.4 mm Hg (max 6.2 mm Hg, min 2.4 mm Hg). Although the area of the anterior tricuspid leaflet was slightly underestimated, we determined that long-term results of tricuspid valve annuloplasty with a Carpentier ring were encouraging.