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Background: Nuclear cardiology permits the estimation of the myocardial infarction size and the result of the thrombolytic therapy. The aim of the study was to demonstrate the feasibility of the planar myocardial scintigraphy with Technetium-99-m-sestamibi in the coronary intensive care unit for the early identification of the infarct size and the result of the thrombolytic therapy., Materials and Methods: We considered 10 patients affected by a first myocardial infarction (5 anterior and 5 inferior wall) then treated with thrombolytic therapy (APSAC 30 U. iv) within an interval of 3 hours from the onset of the symptoms. Technetium-99-m-sestamibi was injected before the thrombolytic therapy and the planar imaging was registered after 2-3 hours with a mobile gamma-camera. After 24 hours and before patient discharge we repeated the scintigraphic evaluation. Within 24 hours from the thrombolytic therapy the coronary angiography was performed for the demonstration of patency of the infarct-related artery. The left ventricle myocardial perfusion was divided in the 3 planar projections into 13 segments. The perfusion in each segment was evaluated with a perfusion score: 0 = normal perfusion, 1 = moderately reduced, 2 = severely reduced, 3 = absent. The sum of the hypoperfused segments represented the infarct size. A perfusion score improvement greater than 40% was considered a marker of reperfusion., Results: The infarct size involved 4.4 +/- 1.4 segments in the anterior and 2 +/- 0.6 segments in the inferior wall infarctions (p < 0.05). The scintigraphic imaging made 24 hours after the myocardial infarction allowed the diagnosis of coronary reperfusion in 7 patients. The coronary angiography demonstrated the infarct related artery patency in 9 patients (all with TIMI perfusion score = 3). The nuclear imaging at patient discharge provided the diagnosis or reperfusion in 8 cases and demonstrated an improvement of the myocardial perfusion score in 5 cases., Conclusion: The scintigraphic imaging with Technetium-99-m-sestamibi in the patients with a myocardial infarction treated with thrombolytic therapy is feasible with a mobile gamma-camera in the intensive coronary care unit. The quality of planar imaging is good and allows the evaluation of myocardial infarct size and efficiency of thrombolytic therapy. An earlier scintigraphic imaging should be taken into consideration for a more timely non-invasive evaluation of patients who need coronary angiography and, if necessary, a rescue PTCA.

Objective: Aim of this perspective study was to assess in patients (pts) with a recent first transmural myocardial infarction (MI) the influence of a physical training, of MI location and of the patency of the infarct-related coronary artery on the modification of the left ventricle volumes and wall motion score., Methods: One hundred and four consecutive pts with a first transmural MI without clinical contraindication (heart failure, moderate or severe mitral regurgitation, severe postinfarction angina, claudication or severe orthopedic problems) were randomly assigned to a rehabilitation group (A) and to a control group (B). Ten days after acute MI all pts underwent a coronary angiography. A complete echocardiographic examination was performed 10 and 90 days after MI, and an ergometric evaluation 20 and 90 days after MI. Ventricle volumes, ejection fraction (EF) and wall motion score were calculated by a two-dimensional echocardiogram. Thirteen pts (12.5%) were excluded from the study because of the bad quality of the echocardiographic images. There were 8 dropouts (7.8%) due to bypass surgery or to coronary angioplasty. Of the 83 pts who have concluded the study 46 (55%) belonged to the Group A and 37 (45%) to the Group B. Thirty-six had anterior MI (20 Group A), 41 inferior MI (22 Group A) and 6 lateral or posterolateral MI (4 Group A)., Results: At the base-line the ventricular volumes, the EF, the wall motion score and the Total Work Capacity (TWC) were not different in the two groups. Three months after the MI the pts of the Group A demonstrated, in comparison with the controls, a reduction of left ventricle end-diastolic volume index (EDVi 75.4 +/- 18.1 ml/m2 vs 85.3 +/- 27.9 ml/m2; p < 0.05) and an increased TWC (7146 +/- 3566 Kgm vs 4494 +/- 2728 Kgm; p < 0.001). In the Group A the comparison of the base-line data with those observed 3 months later showed a reduction of the EDVi from 81.9 +/- 16 to 75.4 +/- 18.1 p < 0.05, of the end-systolic volume index (ESVi) from 43.6 +/- 11.9 to 38.1 +/- 14 ml/m2, p < 0.05, of the wall motion score from 6.7 +/- 2.3 to 5.5 +/- 2.9 p < 0.05 and a great increase of the TWC (from 4483 +/- 2407 Kgm to 7146 +/- 3566 Kgm; p < 0.0001). No parameter in the Group B showed any significant modification in the same period. The tendency to reduce the volume and improve the physical performance with exercise training was greater in the inferior MI (ESVi from 41.3 +/- 12.3 to 34.7 +/- 11.6 ml/m2, p = 0.07 - TWC from 4652 +/- 2446 to 8115 +/- 3954 Kgm, p < 0.001) than in the anterior MI (ESVi from 445.8 +/- 10.7 to 42.1 +/- 17.2 ml/m2, p = ns - TWC from 4085 +/- 2103 to 5829 +/- 2256 Kgm, p < 0.05). When comparing pts with an occluded infarct-related coronary artery with TIMI grade 0-2 flow with those with a patent one (TIMI grade 3 flow), no significant differences in any considered parameter except for the collateral vessels score were found (1.48 +/- 0.97 vs 0.29 +/- 1.64 p < 0.05). After 3 months 20 pts presented larger EDVi compared to the baseline, and compared to the 34 pts with a smaller EDVi, they had a higher serum myocardial enzymatic peak (LDH 2035 +/- 1423 vs 1346 +/- 683 p < 0.01, CK 3096 +/- 2339 vs 2099 +/- 1520, p < 0.05) an inferior collateral score (0.47 +/- 0.77 vs 0.67 +/- 1.98, p < 0.01) and they mainly belonged to the Group B (55%). Twenty pts had an initial EF < or = 40% (range 22-40%): 5 of the 6 pts of this group, who increased the EDVi after 3 months belonged to the Group B while 9 of the 10 pts who reduced it belonged to the Group A., Conclusions: Intensive physical training during the 3 months following a first transmural MI significantly improves the physical performance, reduces the ventricle size and improves the wall motion score. Such improvement could not be found in the control group and is not related to the patency of the culprit coronary artery. The pts with an inferior MI tended to gain a major advantage from the physical activity than the pts with an anterior

Background: Reduced septal uptake of 201-Thallium in patients with left bundle branch block is reported in literature as having a variable frequency (between 14% and 100%) and in such patients the value of exercise Thallium-scintigraphy for the diagnosis of the left anterior descending coronary artery disease is limited by the great number of false-positive tests. The aim of this study was to assess the prevalence and the diagnostic sensitivity of this septal defect in a group of patients with left bundle branch block., Methods: We evaluated the exercise 201-Thallium myocardial scintigraphy of 54 patients with a stable left bundle branch block. The clinical and/or echocardiographic evaluation excluded the presence of primitive, valvular and hypertensive cardiomyopathies and of previous myocardial infarction. The planar myocardial scintigraphic imaging was acquired according to the "stress-redistribution" protocol. Only 37 patients underwent an echocardiographic examination and following clinical and/or scintigraphic indications; 27 patients underwent a coronary angiography for the evaluation of coronary stenosis., Results: The 201-Thallium imaging showed septal defects in 36 patients (67%) and the presence of defects in other segments in 14 patients. The echocardiographic evaluation showed an interventricular septal defect contraction abnormality in 19 cases in the 27 patients with septal defect and in 4 cases in the 10 patients with negative scintigraphy (Fisher NS). Twenty-seven patients (23 with- and 4 without septal defect) underwent a coronary angiography, which showed in 6 cases critical stenosis of the left descending anterior artery, in 5 of the right coronary, in 3 of the Circumflex artery and in 16 normal coronary angiograms. The presence of the septal uptake defect showed a diagnostic sensitivity and specificity for the detection of the left anterior descending coronary artery disease of respectively 67% and 52% (whereas using a semi-quantitative analysis of 100% and 19%). The scintigraphy showed a sensitivity and specificity for the detection of the right coronary artery disease of respectively 80% and 100% and for the circumflex coronary artery stenosis of 0% and 100%., Conclusions: We found a high prevalence of septal perfusion defects (67%) and this results shows a high sensitivity but a low specificity for the diagnosis of the left anterior descending coronary disease; the semi-quantitative analysis improves the sensitivity, but leads to a further reduction of the specificity. The female patients had a prevalence (70%) similar to the general population but demonstrated a higher percentage of false-positive. The 201-Thallium scintigraphy has a high diagnostic accuracy for the detection of the right coronary artery stenosis, while it is less accurate regarding the circumflex artery disease.

Background: Hyperdynamic left ventricular function and increased left ventricular mass has been recently reported in the long-term follow-up of patients after successful repair of aortic coarctation (AoCo)., Methods: We studied 35 patients, mean age 22.7 years (range 1-47), following repair of AoCo in order to evaluate: 1) left ventricular mass and systolic function by M-mode echocardiography in comparison with 20 healthy control subjects; 2) the prevalence of systemic hypertension; 3) systolic blood pressure and the trans-isthmic gradient by CW Doppler at rest and after exercise; 4) subjects with a hypertensive response and/or with a significant trans-isthmic gradient during exercise, correlating such parameters with indexes of left ventricular function and the ratio of aortic isthmus/aortic diaphragmatic diameters (AOI/AOD) by means of Magnetic Resonance (MR). At the time of operation, mean age was 12.4 years (range 1 mo-40 yrs) and the follow-up period was 10.1 years (range 6 mo-26 yrs)., Results: Left ventricular mass index (Mi) was significantly greater in comparison with that of the controls (96.5 +/- 25 vs 71.5 +/- 16.6 g/m2; p < 0.001); the mean velocity of circumferential shortening (mVCFc) was increased (1.4 +/- 0.25 vs 1.2 +/- 0.16 circ/s; p < 0.005); the end systolic meridional stress (ESS) was decreased (37.3 +/- 11.1 vs 47.9 +/- 13.1 g/cm2; p < 0.005) while the peak systolic meridional stress (PSS) was not significantly different in the two groups. Fourteen out of 35 patients (40%) showed an exaggerated mVCFc for the level of ESS, which indicates an increased inotropic state. Hypertension at rest was present in 10 patients (28%). Mean age at the time of operation of the hypertensive group was higher than that of the normotensive one (21.4 +/- 10 vs 8.9 +/- 8.6 yrs; p < 0.001). All patients showed a small systolic gradient across the side of coarctation repair at rest (mean 13.1 mmHg; range 0-30). The exercise test was stopped in 5 patients because of hypertension (> 250 mmHg); 24 patients (80%) showed an exercise-induced hypertension. The mean gradient at maximal exercise was 25.9 mmHg (range 0-52); 6 patients (20%) developed a diastolic gradient. With MR it was possible to evaluate the anatomy of the aortic arch and the descending aorta in all cases. The mean ratio AOI/AOD was 0.81 (range 0.63-1). The age at the time of operation showed a positive correlation with the systolic blood pressure (r = 0.63; p < 0.001) and with Mi (r = 0.45; p < 0.005). The systolic blood pressure and the gradient at maximal exercise also showed a positive correlation (r = 0.40; p < 0.01)., Conclusions: In the long-term follow-up of patients after successful coarctation repair there are persistent alterations of left ventricular function with hypertrophy, hyperkinesia and increased inotropic state. Hypertension at rest and after exercise could persist despite good surgical results.

A young male patient with no risk factors for atherosclerotic disease suffered from an acute myocardial infarction at the age of 22 years, and was subsequently found to have multiple coronary artery aneurysms by coronary angiography. The transthoracic echocardiography was unable to identify coronary anomalies, whereas the transesophageal approach did show aneurysmatic lesions of the left anterior descending artery. These could have been caused by a previous episode of Kawasaki disease, a pathological finding that should be considered in any young adult presenting with proximal discrete coronary artery aneurysms.

Background: Patients with previous coronary artery bypass graft surgery often develop chest pain due to ischemic or nonischemic causes. Noninvasive evaluation of graft patency is thus of obvious potential importance., Methods: In order to assess the efficacy of magnetic resonance imaging (MRI) in evaluating graft patency after coronary artery bypass graft surgery, 16 patients with prior surgery and history of chest pain were studied prospectively by coronarography and MRI. These 16 patients with a total of 40 grafts were evaluated, using MRI with Spin-Echo T1 technique within 3.6 +/- 4.4 days from coronarography with a 0.5 Tesla magnet, cardiac and respiratory gating and scannings in transaxial planes. A graft was defined as patent if a signal void was identified in at least two different slices in a position consistent with a bypass graft. Images were analyzed by two different observers aware of the type of surgery but not the result of the coronarography., Results: Thirty-six out of the 40 grafts were classified correctly by MRI. Twenty-eight grafts were patent as shown by coronarography; 26 of them were classified correctly by MRI. Twelve grafts were shown as occluded; 10 of them were classified correctly by MRI. In particular, all of the 14 grafts to the left anterior descending artery (3 of them using the internal mammary artery), 13/16 of the grafts to the left circumflex artery and 9/10 of the grafts to the right coronary artery were classified correctly., Conclusions: This study demonstrates the capability of MRI to evaluate coronary artery bypass graft patency with a sensitivity of 92.8% and specificity of 83.3%; this technique has significant clinical limitations because resolution is not adequate to evaluate the presence of graft stenosis.

Background: The exogenous adenosine is able to provoke a coronary vasodilation, which is the same as the one provoked by the papaverine and greater than the one provoked by the dipyridamole. We report our experience in using exogenous adenosine in association with technetium-99m-sestamibi tomoscintigraphy for a diagnostic test on the coronary artery disease (CAD)., Methods: We considered 22 patients (18 male and 4 female, mean age 57 years) affected by angiographically demonstrated coronary artery disease (stenoses > or = 50%). Adenosine was infused at a dosage of 0.070 mg/kg/min for 3 minutes and, if well tolerated, the dosage was increased to 0.140 mg/kg/min; in the third minute of the major dosage the radioisotope was injected. The myocardial perfusion imaging at rest was evaluated on the following day., Results: The test was completed on 21 of the 22 patients, and 20 of the latter were subjected to the maximal dosage of the adenosine infusion. Clinically irrelevant adverse effects were observed in 20 cases; only one patient developed a II degree type 1 AV block. Angina occurred in 19 patients. Coronary angiography demonstrated significant stenosis of 35 vessels: the left anterior descending (LAD) in 14 patients, the left circumflex (LCx) in 8 and the right coronary artery (RCA) in 13. In detecting CAD, the test in our study demonstrated a sensitivity of 85% in the LAD disease, of 89% in the LCx disease and of 77% in RCA disease., Conclusions: The adenosine infusion associated with technetium-99m-sestamibi tomoscintigraphy demonstrated an elevated incidence of adverse effects which are of short duration and clinically irrelevant. The method was shown to be highly sensitive in detecting the CAD.

Mitral valvuloplasty with an Inoue balloon catheter was performed at our institution in 15 patients affected by mitral stenosis. All were severely symptomatic (class NYHA III or IV). Transthoracic and transesophageal echocardiography showed a mitral score less than 10 (Wilkins criteria). Patients with thrombi in the left atrium and those with important mitral regurgitation were excluded. The mitral valve area increased from 0.98 +/- 0.2 to 1.89 +/- 0.4 cm2 and the transvalvular gradient decreased from 18.2 +/- 7.5 to 6.7 +/- 3.7 mmHg. There was a small increase of the mitral regurgitation. Two complications occurred during the procedure: the first was a haemopericardium, which was percutaneously drained, and the other a rupture of the anterior mitral leaflet with acute, severe mitral regurgitation necessitating urgent surgical correction. Applying the criteria of Herrmann, the results were optimal in 11 and suboptimal in 3 cases.

2D-echocardiography, together with simultaneous measurement of systolic blood pressure and pulsed doppler examination of the transmitral flow were used to assess the left ventricular (LV) systolic and diastolic function during sequential pacing at 4 different atrioventricular (AV) intervals (50, 100, 150, 200 msec), and VVI pacing under the same rate of 90 beats/min in 13 patients (pts), mean age 61.25 +/- 8.26 years with DDD pacemakers implanted for complete AV block. The pts were divided into 2 groups: group I was comprised of 7 subjects showing no clinical abnormalities and normal echocardiograms, and group II of 6 hypertensive subjects with LV hypertrophy and normal systolic function on echocardiography. There was no change in LV diastolic dimension, but a depression in LV systolic function and contractility were shown by the conversion from DDD to VVI pacing in all pts, particularly in group II VVI pacing caused mitral regurgitation with LV filling pattern changing from beat to beat. By changing the AV interval during DDD pacing, the LV filling pattern was modified in all pts. Systolic performance showed little change in group I, whereas in group II more evident modifications were seen. An optimal AV delay, defined as the delay with maximal stroke volume, was identified in all subjects as being 100 and 150 ms in group I and group II respectively. Echo-doppler can thus provide useful information in choosing the mode of pacing and in programming optimal AV delay. In contrast to normal ventricles the systolic performance in hypertrophic ventricles is highly influenced by variation in the AV delay.(ABSTRACT TRUNCATED AT 250 WORDS)

Cor triatriatum (CT) is a rare congenital defect, surgically correctable, and sometimes difficult to diagnose by cardiac catheterization. This report describes three young patients with this particular defect, one of whom was sent to us because of signs of right ventricular failure. The diagnosis of CT was made by transesophageal echocardiography and confirmed by cardiac catheterization and surgical data. The other two cases underwent cardiac catheterization and cardiac surgery during infancy for other congenital defects. The diagnosis of CT was made only during post-operative controls by transthoracic echocardiography. In these two cases transesophageal echocardiography provided the most valuable information about the morphological features of the membrane and the mitral valve, and about the flow between the two left atrial chambers.

We report the case of a 44-year-old woman affected by Churg-Strauss syndrome (systemic vasculitis with eosinophilia, bronchial asthma and pulmonary infiltrations). Congestive heart failure developed, caused by severe myocardial and pulmonary involvement. Conventional treatment and steroids induced remission of symptoms.

Thirteen patients with atrial septal defect (ASD), 12 ostium secundum type, 1 ostium primum type and left-to-right shunt were studied by M-mode and two-dimensional echocardiography and then by intravenous contrast study. Diagnostic confirmation was obtained in 12 cases by cardiac catheterization and angiocardiography. The purpose of the study was to assess the value of contrast echocardiography in the diagnosis of ASD without pulmonary hypertension, since it is known that the standard echocardiographic investigation is rather unsatisfactory in this type of malformation. M-mode echocardiography with contrast injection has been diagnostic in 12 cases (92.3%), by visualising contrast echos in the mitral tunnel. The overall reliability of the two-dimensional contrast-echocardiography was reduced in our cases by a fairly high number of inaccurate results. The right to left shunting of injected contrast does not seem to depend on the haemodynamic parameters considered, such as right atrial pressure, right ventricular end-diastolic pressure, pulmonary artery pressure, and pulmonary arteriolar resistance.

Nine patients, 7 males, 2 females, mean age 36 years, with myotonic muscular dystrophy who had no cardiac symptoms underwent M-mode echocardiography (e.), systolic time intervals (STI) measurement by simultaneous recordings of the electrocardiogram, phonocardiogram and carotid arterial pulse, and single-pass radionuclide angiocardiography (RNA) in order to assess the left ventricular function. The ejecting phase indexes measured by echocardiography (fractional shortening, mean velocity of circumferential fiber shortening) were slightly depressed in 1 case and an abnormal PEP/LVET ratio was found in 3 cases. The ejection fraction measured by radionuclide angiocardiography was abnormal in 1 case who showed a diffuse hypokinesia. The IVI%, a new isovolumic phase index obtained by echocardiography, was abnormal in all patients. It is concluded that the IVI% seems more sensitive than the ejecting phase indexes calculated by echocardiography or radionuclide angiocardiography and the PEP/LVET ratio in detecting abnormalities of left ventricular function in patients with myotonic muscular dystrophy and no clinical signs of heart disease.

Purpose of this study was to assess if the isovolumic index (IVI%) was able to detect the presence of critical coronary artery disease (CAD) in a group of 43 patients with anginal chest pain and normal left ventricular volumes and ejection fraction. The left ventricular function was before evaluated with invasive method and then the IVI% was allowed in every patient. The IVI% was able to recognize early abnormalities of isovolumetric phases of the left ventricle and differentiated normal subjects (IVI% = 40.07 +/- 2.82) from patients with CAD (IVI% = 60.87 +/- 12.49; p less than 0.01). The only parameter of left ventricular function invasively calculated able to separate normal patients from patients with significant CAD were the muscular stiffness of the left ventricle (p less than 0.01).

We have performed a multi-centre study with 47 outpatients in order to evaluate the efficacy of Verapamil (V) in the treatment of stable effort angina, and to compare the effect of two different doses of the drug (240 and 360 mg/die). The protocol consisted of a first period of Placebo, followed by the double-blind randomized cross-over administration of Placebo (P) and Verapamil (V) in doses of 240 and 360 mg/die. The symptomatology, the consumption of TNG, the ECG pattern at rest and during exercise, the maximum exercise tolerance during exercise and the rate of recovery were evaluated at the end of each 1 month period. V. provided a significant reduction of the number of angina attacks and of the consumption of TNG pills with improvement of symptomatology. The maximum exercise performance improved without changes in maximum rate pressure double product. A decrease of double product was observed at rest and during the recovery period. The higher dose of V. (360 mg/die) provides a better improvement in the number of angina attacks, in the symptomatology, in the double product at rest, and in the rate of recovery than the lower dose (240 mg/die). Thus these data indicate that V. provides anti-anginal efficacy by reducing myocardial oxygen demand, and increases exercise tolerance in effort angina patients.

We report the case of a 45-year-old man with acquired aortic regurgitation and anomalous origin of the left circumflex coronary artery from the pulmonary artery.

The aim of the study was to compare the evaluation of the left ventricular systolic function performed both by angiography and 2D-echocardiography on 80 subjects (31 with coronary artery disease, 18 with left ventricular volume overload, 10 with left ventricular pressure overload, 14 with mitral valve disease and 7 normal controls). The 2D-echocardiograms of the left ventricle with simultaneous measurement of the right arm systolic blood pressure was performed within 24 hours of the angiographic examination. The following parameters were obtained using the two methods: end-diastolic volume index, end-systolic volume index, ejection fraction, left ventricular mass index, mass/volume ratio, end-systolic circumferential stress, contractility expressed as end-systolic circumferential stress/end-systolic volume ratio; the end-systolic circumferential stress/ejection fraction ratio was calculated only by 2D-echocardiography. The afterload and contractility were not calculated in subjects with coronary artery disease and left ventricular outflow gradient. No statistically significant differences were shown between the two methods, except a slight under-estimation by echocardiography of the angiographic end-diastolic volume index (93.1 +/- 38.9 ml/m2 vs 115 +/- 39.9 ml/m2; p less than 0.01) and over-estimation of the mass/volume ratio (1.38 +/- 0.33 g/ml vs 1.2 +/- 0.44 g/ml; p less than 0.01) was shown between the two methods for all parameters. A depressed contractile state was also demonstrated by the end-systolic circumferential stress/ejection fraction ratio. The inter and intraobserver variability was 6.6 +/- 4.4% (range 0.16%) and 4.2 +/- 3% (range 1.11%) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of the present study is to make a contribution to the understanding of the electrogenetic interpretation of left ventricular hypertrophy caused by volume overload. Thirty-two cases of isolated aortic valve regurgitation with electrocardiographic evidence of left ventricular hypertrophy were studied by vectorcardiography in order to measure the 20 msec vector both in the spatial and horizontal plane, and by M-Mode echocardiography to obtain the interventricular septal and posterior wall thickness and the end diastolic dimension of the left ventricle. The following relations were analyzed: a) between the interventricular septal thickness and the amplitude of the 20 msec vector in the spatial and horizontal plane; b) between the end diastolic dimension of the left ventricle and the amplitude of the 20 msec vector. We also explored the possibility to distinguish by means of the 20 msec vector amplitude between patients with and without disproportionate septal thickening. We found no correlation either between interventricular septal thickness and amplitude of the 20 msec vector, or between left ventricular end diastolic dimension and amplitude of the 20 msec vector. It was not possible to distinguish by means of the amplitude of the 20 msec vector between the cases of left ventricular hypertrophy with disproportional septal thickening and those without it.

The isovolumic index (IVI%), a new parameter of left ventricular function defined as (isovolumic contraction + isovolumic relaxation time)/left ventricular ejection time, is easily obtained from a routine echocardiogram. By simultaneous recordings of an electrocardiogram, a carotid arterial pulse tracing and the mitral valve echocardiogram, we calculated the IVI% as (time from R wave to MV opening-LVET)/LVET %. 90 normal subjects, mean age 38.32 +/- 11.8 years (range 20-60), underwent an echocardiographic study in order to calculate this index. The value of the IV% was 39.75% +/- 6.82 (range 21.4%-52.3%). The index was heart rate independent and showed a weak positive correlation with age (y = 32.4 + 0.19x; r = 0.33; p less than 0.01). The intraobserver and interobserver variability were 2.6% and 3.6%. The methodologic aspects of the calculation of the IVI% are discussed.