Effects of verapamil on left ventricular systolic function and diastolic filling in patients with hypertrophic cardiomyopathy

Failure of calcium channel blockers to improve ventricular relaxation in humans

OBJECTIVES

The objective of this study was to ascertain whether the reversal of low peak filling rates after administration of calcium channel blockers in patients with diastolic dysfunction indicates true improvement in the rate of ventricular relaxation and left ventricular end-diastolic pressure measured by invasive indexes.

BACKGROUND

Depressed filling rates measured noninvasively have been associated with diastolic dysfunction, specifically abnormal relaxation of the left ventricle. There is a reversal of these low peak filling rates after administration of calcium channel blockers.

METHODS

Doppler echocardiographic measurements of peak filling rates were made and invasive high fidelity manometer-tipped pressures were measured before and after administration of verapamil (0.1 mg/kg body weight) in 20 patients with coronary artery disease who had an ejection fraction > 40% and decreased peak filling rates.

RESULTS

Verapamil caused significant increases in the peak filling rate, as measured by early transmitral (E) flow velocity, from 0.57 +/- 0.16 m/s to 0.77 +/- 0.15 m/s (p < 0.01), indicating reversal of decreased peak filling rates. Concomitantly, left ventricular end-diastolic pressure increased from 18.0 +/- 7.7 mm Hg to 24.1 +/- 9.0 mm Hg (p < 0.001). The time constant of relaxation was variable, with an overall significant increase from 45.8 +/- 10.4 ms to 53.2 +/- 14.6 ms (p = 0.01).

CONCLUSIONS

Verapamil administered intravenously produced reversal of decreased peak filling rates in patients with coronary artery disease and normal ventricular function. However, there was an increase in left ventricular end-diastolic pressure as well as an overall prolongation of the time constant of relaxation. Therefore, changes in peak filling rates do not accurately reflect the response of ventricular relaxation to drug interactions. Thus, calcium channel blockers should be used cautiously in the empiric treatment of patients with diastolic dysfunction.

Noninvasive detection of left ventricular diastolic dysfunction using M-mode echocardiography to assess left ventricular posterior wall kinetics in hypertrophic cardiomyopathy

In patients with hypertrophic cardiomyopathy (HC), it is difficult to determine the severity of left ventricular (LV) diastolic dysfunction. Three different patterns of LV posterior wall motion were found by M-mode echocardiography in patients with HC, and the use of these patterns is proposed as a new noninvasive index of the severity of LV diastolic dysfunction. M-mode echocardiograms were recorded prospectively from 35 patients with HC, and the posterior wall motion pattern in late systole and early diastole was classified into the following 3 types: (1) normal motion (n = 9); (2) flat motion--flat motion from late systole to early diastole, followed by rapid backward movement (n = 13); and (3) downward motion--slow backward movement from late systole (n = 13). There were no differences in the severity or type of hypertrophy, LV systolic function and pulsed Doppler indexes of LV filling among these 3 groups. However, LV end-diastolic pressure was increased in the groups with flat (15 +/- 6 mm Hg) and downward (16 +/- 9 mm Hg) motion. Furthermore, the maximal rate of decrease in LV pressure (normal 1,450 +/- 300, flat 1,250 +/- 300 and downward 860 +/- 80 mm Hg/s) and the time constant of LV pressure reduction (normal 60 +/- 15, flat 70 +/- 25 and downward 101 +/- 34 ms) showed a stepwise deterioration from the normal to the flat and then to the downward motion groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of relaxation velocity parameters by calcium channel blockers in the aging rabbit myocardium

Normal aging in man is known to be associated with a reduction in left-ventricular diastolic function, including the rates of relaxation and filling. Calcium channel blockers have been reported to improve left-ventricular diastolic function in patients with various forms of heart disease. Clinically, the action of calcium channel blockers may be related to either a direct myocardial effect or may be secondary to the peripheral or coronary vasodilation effects. The purpose of this study is to investigate a possible direct effect of calcium channel blockers on modulation of the reported age-related reduction in myocardial relaxation. The direct effects on myocardial relaxation of the dihydropyridine calcium channel blocker, nifedipine, were studied in isolated, perfused interventricular septa and left-ventricular wall from eight young (ages 9 to 18 months) and 14 old (ages 3 to 5 years) rabbits. Septa were perfused with oxygenated Ringer's solution and paced at 48 beats/min. Maximum relaxation velocity per unit of developed tension [-dT/dt]/T, and relaxation time per unit of developed tension tR/T were continuously measured before and after infusion of calcium channel blockers. In absence of drugs, the older rabbits demonstrated a mean [-dT/dt]/T which was 32% lower (p < 0.003) and a mean tR/T which was 45% higher (p < 0.005) than the younger rabbits. When nifedipine was introduced at concentrations > 10(-8) M equivalent to doses above the therapeutic free-plasma concentration in humans, all contraction and relaxation parameters were depressed. However, at lower doses, equivalent to doses in the clinical therapeutic range, [-dT/dt]/T was increased in the older rabbit septa by 18% in the presence of nifedipine. tR/T was shortened in the older rabbit septa by 17% in the presence of nifedipine. Myocardial relaxation in older rabbits after drug infusion approximated these parameters in the younger rabbits prior to drug infusion (P = NS). Calcium channel blockers had similar beneficial effects on the relaxation properties of the myocardium in younger rabbits. All beneficial effects were observed at concentrations of calcium channel blockers which were within and below the clinically therapeutic range of plasma free drug concentration, i.e., 5 x 10(-9) to 4 x 10(-8) M. Potential differences in relaxation effects related to different segments of the myocardium and different mechanical recording vectors were evaluated. Isolated left ventricle preparations from aging rabbits demonstrated improvements in tR/T and [-dT/dt]/T similar to those observed in the septum. Furthermore, improvement in mechanical function along the y-axis and x-axis vectors of the septum was similar.(ABSTRACT TRUNCATED AT 400 WORDS)

Maximum stress-volume index ratio of the left ventricle in hypertrophic cardiomyopathy

To evaluate the left ventricular contractile state in patients with nonobstructive hypertrophic cardiomyopathy (HCM), we analyzed the maximum stress-volume index ratio (MSVR) using catheter-tip cineangiography in 11 patients with HCM and 16 normal subjects. The value of the MSVR in normal subjects was 6.48 +/- 1.25 kdyn/cm5/m2 (mean +/- SD) and we defined the range of the mean +/- 2 SD as the normal MSVR range. Six patients with HCM placed inside the normal MSVR range (IN), but the other 5 patients placed outside and to the right of the normal range (RIGHT). This suggests that the contractile states of the patients of the RIGHT group were depressed. Compared with IN, the end-diastolic and end-systolic volume indices of RIGHT were larger (EDVI; 69.3 +/- 6.9 vs. 96.1 +/- 11.1 ml/m2, p less than 0.01, ESVI; 18.2 +/- 3.2 vs. 29.1 +/- 8.3 ml/m2, p less than 0.05), but the ejection fraction did not differ (IN 73.5 +/- 5.7 vs. RIGHT 69.6 +/- 8.3%, NS). End-diastolic pressure of IN and RIGHT was higher than that of normal subjects (IN 16.5 +/- 4.5, RIGHT 16.7 +/- 4.6 vs. 8.3 +/- 2.5 mm Hg, both p less than 0.05), but there was no difference between the two groups in HCM. End-systolic pressure did not differ among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulsed Doppler echocardiographic indices of left ventricular diastolic function in normal subjects

To establish the normal limits for various pulsed Doppler echocardiographic indices of left ventricular diastolic function, 92 healthy volunteers aged from 5 to 75 years were prospectively studied. The influence of various variables including age, gender, body surface area, fractional shortening, and left ventricular mass on these parameters was also assessed. Mean (2SD) values for 15 direct and 11 derived parameters were analyzed from transmitral inflow velocity waveform. No statistically significant differences were observed between males and females for any of these parameters. On stepwise multivariate linear regression analysis, age was found to be an independent strong determinant (p less than 0.001) of peak velocity of early diastolic filling wave, area of atrial filling period, deceleration slope, normalized peak filling rate, and early filling fraction. There was a significant correlation between heart rate and time to peak early diastolic velocity, total diastolic time period, early diastolic period, atrial filling period, and atrial filling fraction. It was further observed that a significant correlation (p less than 0.001) persisted between both age and heart rate with area of early filling period, one-third filling area, one-half filling area, ratio of early to atrial peak velocity and area, atrial filling fraction, and one-third filling fraction. None of the parameters were found to correlate with fractional shortening or left ventricular mass. Thus an effort was made to establish normal limits for various Doppler-derived parameters in healthy volunteers for future comparison in diseased states.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in left ventricular diastolic function in conscious dogs with pacing-induced heart failure

We investigated in conscious dogs (a) the effects of heart failure induced by chronic rapid ventricular pacing on the sequence of development of left ventricular (LV) diastolic versus systolic dysfunction and (b) whether the changes were load dependent or secondary to alterations in structure. LV systolic and diastolic dysfunction were evident within 24 h after initiation of pacing and occurred in parallel over 3 wk. LV systolic function was reduced at 3 wk, i.e., peak LV dP/dt fell by -1,327 +/- 105 mmHg/s and ejection fraction by -22 +/- 2%. LV diastolic dysfunction also progressed over 3 wk of pacing, i.e., tau increased by +14.0 +/- 2.8 ms and the myocardial stiffness constant by +6.5 +/- 1.4, whereas LV chamber stiffness did not change. These alterations were associated with increases in LV end-systolic (+28.6 +/- 5.7 g/cm2) and LV end-diastolic stresses (+40.4 +/- 5.3 g/cm2). When stresses and heart rate were matched at the same levels in the control and failure states, the increases in tau and myocardial stiffness were no longer observed, whereas LV systolic function remained depressed. There were no increases in connective tissue content in heart failure. Thus, pacing-induced heart failure in conscious dogs is characterized by major alterations in diastolic function which are reversible with normalization of increased loading condition.

Impact of surgical relief of outflow obstruction on thallium perfusion abnormalities in hypertrophic cardiomyopathy

BACKGROUND

To assess the impact of surgical relief of left ventricular outflow obstruction on myocardial perfusion abnormalities in patients with obstructive hypertrophic cardiomyopathy, 20 symptomatic patients who underwent a septal myectomy or mitral valve replacement were studied with assessment of myocardial perfusion during exercise by 201Tl emission computed tomography before and 6 months after surgery.

METHODS AND RESULTS

Before surgery, 15 patients had myocardial perfusion defects during exercise that completely normalized at rest, one patient had both reversible and fixed perfusion defects, two patients had fixed defects only, and two patients had normal exercise and rest thallium scans. After surgical relief of left ventricular outflow obstruction (basal gradient reduced from 62 +/- 40 to 7 +/- 12 mm Hg, p less than 0.001; peak provokable gradient reduced from 131 +/- 27 to 49 +/- 36 mm Hg, p less than 0.001), repeat exercise thallium studies showed complete normalization of perfusion defects in 11 patients, including the two patients with fixed defects alone before surgery, and improvement in the magnitude and distribution of perfusion defects in five additional patients. This was associated with a significant reduction in the number of patients with reversible regional defects (five patients compared with 13 patients before surgery, p = 0.026) and of patients with endocardial hypoperfusion (four patients compared with 12 patients before surgery, p = 0.024). Furthermore, increased lung uptake of thallium was noted in five patients after surgery, compared with 12 patients before surgery (p = 0.055). Only two patients with reversible perfusion defects before surgery had unchanged postoperative studies. However, four patients acquired new fixed defects as a consequence of surgery, and two of these four had the greatest severity and distribution of left ventricular hypertrophy by echocardiography. These four patients experienced a substantially greater decrease in ejection fraction (-26 +/- 15%) after surgery than the remaining patients (-3 +/- 14%, p less than 0.01).

CONCLUSIONS

Surgical relief of left ventricular outflow obstruction results in normalization or improvement of myocardial perfusion in the majority of patients with reversible and fixed perfusion defects by 201Tl scintigraphy. However, surgery may result in myocardial injury and scarring, with consequent decreased left ventricular ejection fraction in some patients.

Mechanisms of exercise limitation in hypertrophic cardiomyopathy

To assess the relation of exercise capacity to indexes of systolic and diastolic function in hypertrophic cardiomyopathy, 81 patients underwent two-dimensional echocardiography, technetium-99m equilibrium radionuclide angiography acquired in list mode and maximal, symptom-limited, treadmill exercise testing with measurement of maximal oxygen consumption (VO2 max). VO2 max for the group was 13.9 to 49.3 (mean 25.4) ml/min per kg. Thirty-six patients (44%) achieved less than or equal to 70% of age-predicted VO2 max. Patients with such a degree of limitation were more likely to be in New York Heart Association functional class II or III (23 of 36 vs. 14 of 45; p = 0.005); there was no such relation between VO2 and the incidence and magnitude of rest left ventricular outflow tract pressure gradient greater than 30 mm Hg (11 of 36 vs. 11 of 45; p = NS and 58 +/- 24 vs. 65 +/- 19 mm Hg; p = NS). In the 22 patients with a left ventricular outflow tract gradient, the ratios of peak ejection to peak filling rate and of atrial contribution to left atrial dimension were related to percent of the age-predicted VO2 max (r = 0.49, p = 0.02 and r = 0.54, p less than 0.02). These ratios reflect impaired left ventricular systolic performance and atrial systolic failure, respectively. Stepwise discriminant analysis revealed these two ratios to be the two strongest predictors (p = 0.0001) of patients with a left ventricular outflow tract gradient whose VO2 max was less than or equal to 70% of the age-predicted value (sensitivity 90%, specificity 100%).(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and left ventricular responses to exercise stress in asymptomatic patients with valvular aortic stenosis

Patients with heart disease may have myocardial ischemia or left ventricular (LV) dysfunction without symptoms. The exercise responses of 14 asymptomatic patients with valvular aortic stenosis (AS) were studied using treadmill testing, thallium-201 scintigraphy and radionuclide angiography. Compared with age- and gender-matched control subjects, patients with AS demonstrated reduced exercise tolerance (10.7 +/- 2.5 vs 13.3 +/- 4.2 min; p = 0.06) and maximal oxygen consumption (26.7 +/- 6.3 vs 36.3 +/- 9.5 ml O2/min/kg; p = 0.004) associated with decreased peak systolic blood pressure response to exercise (177 +/- 18 vs 214 +/- 42 mm Hg; p less than 0.004). Ten of 14 patients developed ST-segment depression during exercise, only 3 of whom had reversible thallium defects. Patients with AS tended to have greater LV ejection fractions at rest (65 +/- 11 vs 58 +/- 7; p = 0.08) and significantly decreased early peak filling rates (4.8 +/- 1.3 vs 6.1 +/- 0.6 stroke volume/s; p = 0.003) compared with those of control subjects. During maximal supine exercise, patients with AS had less of an increase in ejection fraction (2 +/- 9 vs 15 +/- 7%; p less than 0.001) associated with a decrease in end-diastolic (-7 +/- 15 vs +5 +/- 16%; p = 0.06) and stroke (-6 +/- 17 vs +30 +/- 13%; p less than 0.001) volumes from baseline measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the calcium channel-blocking agents diltiazem and verapamil for treatment of feline hypertrophic cardiomyopathy

To determine the efficacy of and clinical response to several pharmacologic agents for treatment of idiopathic hypertrophic cardiomyopathy in cats, 17 symptomatic cats were randomized to treatment with either propranolol, diltiazem, or verapamil. Clinical, laboratory, radiographic, electrocardiographic, and echocardiographic data were obtained before treatment and after 3 and 6 months of chronic oral therapy. Too few of the cats receiving propranolol or verapamil survived long enough to obtain long-term data needed to make statistical comparisons between groups. However, all 12 cats ultimately treated with diltiazem became asymptomatic, and no adverse effects from this drug were noted in any of these cats. Treatment with diltiazem was associated with a significant reduction of pulmonary congestion assessed radiographically (P less than 0.01), and improved ventricular filling based on echocardiographic measurements of left atrial size (P less than 0.05), left ventricular internal diastolic dimension (P less than 0.05), and relaxation time index (P less than 0.001). There was also a drug-related improvement in jugular venous oxygen tension (P less than 0.001) and blood lactate concentration (P less than 0.01) suggesting improved peripheral perfusion in the cats receiving diltiazem. The results indicate that diltiazem provides an effective and apparently safe treatment for the management of feline hypertrophic cardiomyopathy.

Evidence for or against the efficacy of calcium channel blockers for management of hypertrophic cardiomyopathy in cats

The positive lusitropic and direct coronary vasodilating properties of the calcium channel blocking agents are beneficial therapeutic effects not provided by the beta-adrenergic blocking agents for the management of feline HCM. Data from cats studied at the University of Tennessee suggest that diltiazem more consistently alleviates clinical signs and more effectively prolongs survival in cats with HCM than either propranolol or verapamil. Orally administered diltiazem appears to have sustained beneficial effects on left ventricular filling and cardiac performance based on its ability to reduce resting heart rate, decrease blood lactate concentration, increase venous oxygen tension, improve echocardiographic parameters, and resolve radiographic abnormalities. Long-term diltiazem administration may also reverse myocardial hypertrophy in some patients. There appear to be few if any side effects of this drug. Diltiazem, therefore, provides a safe and effective approach for the management of feline HCM.

Influence of left ventricular diastolic filling on symptoms and survival in patients with decreased left ventricular systolic function

The relation between left ventricular (LV) filling variables measured by gated blood pool radionuclide ventriculography and clinical symptoms and survival was examined in 93 patients who had decreased LV systolic function. The diastolic data were not significantly associated with clinical symptoms. Time to peak filling rate, peak filling rate and ejection fraction were associated independently with survival free of cardiac death (chi-square = 7.74, 5.91 and 3.92, respectively, by stepwise Cox regression analysis). A short time to peak filling rate or increased peak filling rate was associated with decreased survival, whereas the opposite indicated a good prognosis. One-year Kaplan-Meier survival was 73 and 98% when time to peak filling rate was below or above the median value of 167 ms, respectively, 82 and 90% when peak filling rate was above or below the median value of 1.67 end-diastolic volumes per second, respectively, and 76 and 95% when LV ejection fraction was below or above the median value of 0.35, respectively. Thus, filling variables (time to peak filling rate and peak filling rate) measured by radionuclide ventriculography may be valuable in predicting survival in patients with decreased LV systolic function.

Changes in left ventricular diastolic filling during the development of left ventricular hypertrophy: observations using Doppler echocardiography in a unique canine model

To examine changes in diastolic left ventricular filling during the development of left ventricular hypertrophy, serial pulsed Doppler echocardiographic studies were performed in a canine model of left ventricular hypertrophy induced by neurogenic pressor episodes. This model is unique since left ventricular hypertrophy develops without sustained hypertension. The neurogenic pressor episodes produced progressive increases in left ventricular mass of 17% by 3 weeks (p less than 0.03) and 23% by 9 weeks (p less than 0.001). During the course of hypertrophy development, there were no changes in resting heart rate, blood pressure, left ventricular volumes or ejection fraction, or end-systolic wall stress. However, peak early filling (peak E) velocity decreased from 65 +/- 5 cm/sec to 53 +/- 4 cm/sec by 3 weeks (p less than 0.05) and remained depressed at 9 weeks. In addition, peak E/A (the ratio of early to late peak filling) decreased by 3 weeks (p less than 0.01) and the contribution of atrial filling to total left ventricular diastolic filling increased by 9 weeks (p less than 0.005). There were significant correlations between the changes in left ventricular mass and the change in peak E velocity at 3 weeks (r = -0.92, p less than 0.001) but not at 9 weeks. These data indicate that left ventricular filling abnormalities occur early in the course of the development of left ventricular hypertrophy, are not a result of loading alterations related to sustained hypertension, and do not change significantly following increasing stages of hypertrophy.

Effects of acute alterations in left ventricular loading conditions on peak filling rate in the denervated (transplanted) ventricle

Peak filling rate is an indicator of left ventricular (LV) diastolic function. It is influenced by heart rate, loading conditions, sympathetic nervous system activity, ejection fraction and other factors. To determine the effect of altered loading conditions on peak filling rate, independent of heart rate and sympathetic nervous system activity, 12 patients were studied 3 weeks after orthotopic heart transplantation. Plasma catecholamine level, heart rate and ejection fraction were not changed by any maneuver. Nitroglycerin caused a decrease in pulmonary artery wedge pressure (9 +/- 2 to 6 +/- 1 mm Hg, p less than 0.001) and in absolute peak filling rate (46.0 +/- 3.0 to 42.8 +/- 2.5 kcts/s, p less than 0.01), but no change in normalized peak filling rate. Volume infusion increased pulmonary artery wedge pressure (9 +/- 2 to 12 +/- 2 mm Hg, p less than 0.001) and absolute peak filling rate (46.0 +/- 3.0 to 51.5 +/- 5.3 kcts/s, p less than 0.01), but peak filling rate normalized to stroke volume was unchanged. During nitroglycerin and volume infusions, there was a high correlation between changes in pulmonary artery wedge pressure and absolute peak filling rate (r = 0.82, p less than 0.001). With normalization of peak filling rate, these variables correlated less well. With methoxamine, 4 patients demonstrating systolic dysfunction had a decrease in absolute and normalized peak filling rate despite a large increase in pulmonary artery wedge pressure. The other 8 patients without systolic dysfunction had an increase in pulmonary artery wedge pressure with increased absolute but unchanged normalized peak filling rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial metabolic, hemodynamic, and electrocardiographic significance of reversible thallium-201 abnormalities in hypertrophic cardiomyopathy

BACKGROUND

Exercise-induced abnormalities during thallium-201 scintigraphy that normalize at rest frequently occur in patients with hypertrophic cardiomyopathy. However, it is not known whether these abnormalities are indicative of myocardial ischemia.

METHODS AND RESULTS

Fifty patients with hypertrophic cardiomyopathy underwent exercise 201Tl scintigraphy and, during the same week, measurement of myocardial lactate metabolism and hemodynamics during pacing stress. Thirty-seven patients (74%) had one or more 201Tl abnormalities that completely normalized after 3 hours of rest; 26 had regional myocardial 201Tl defects, and 26 had apparent left ventricular cavity dilatation with exercise, with 15 having coexistence of these abnormal findings. Of the 37 patients with reversible 201Tl abnormalities, 27 (73%) had metabolic evidence of myocardial ischemia during rapid atrial pacing (myocardial lactate extraction of 0 mmol/l or less) compared with four of 13 patients (31%) with normal 201Tl scans (p less than 0.01). Eleven patients had apparent cavity dilatation as their only 201Tl abnormality; their mean postpacing left ventricular end-diastolic pressure was significantly higher than that of the 13 patients with normal 201Tl studies (33 +/- 5 versus 21 +/- 10 mm Hg, p less than 0.001). There was no correlation between the angiographic presence of systolic septal or epicardial coronary arterial compression and the presence or distribution of 201Tl abnormalities. Patients with ischemic ST segment responses to exercise had an 80% prevalence rate of reversible 201Tl abnormalities and a 70% prevalence rate of pacing-induced ischemia. However, 69% of patients with nonischemic ST segment responses had reversible 201Tl abnormalities, and 55% had pacing-induced ischemia.

CONCLUSIONS

Reversible 201Tl abnormalities during exercise stress are markers of myocardial ischemia in hypertrophic cardiomyopathy and most likely identify relatively underperfused myocardium. In contrast, ST segment changes with exercise and systolic compression of coronary arteries on angiography are unreliable markers of inducible myocardial ischemia in hypertrophic cardiomyopathy. Apparent cavity dilatation during 201Tl scintigraphy may indicate ischemia-related changes in left ventricular filling, with elevation in diastolic pressures and endocardial compression.

Sudden death during empiric amiodarone therapy in symptomatic hypertrophic cardiomyopathy

Amiodarone is reported to improve symptoms and to prevent sudden death in patients with hypertrophic cardiomyopathy (HC). Amiodarone treatment (loading dose 30 g given over 6 weeks; maintenance dose 400 mg/day) was prospectively evaluated in 50 patients with HC in whom the drug was initiated because of symptoms refractory to conventional drug therapy (calcium antagonists and beta blockers). Twenty-one (42%) patients had ventricular tachycardia (VT) during Holter monitoring. Amiodarone significantly and often markedly improved the patients' New York Heart Association functional class status (from 3.3 to 2.7 at 2 months, p less than 0.001) and treadmill exercise duration (p less than 0.001). Eight patients, however, died (7 suddenly) during a mean follow-up period of 2.2 +/- 1.8 years. Of the 7 sudden deaths, 6 occurred within 5 months of initiation of treatment. The 6-month and 1- and 2-year survival rates were 87, 85 and 80%, respectively. The survival rate of patients with VT was significantly worse than that of patients without VT (61 vs 97% at 2 years; p less than 0.01). Sudden death occurred despite abolition of VT on Holter monitoring. Amiodarone increased left ventricular peak filling rate by radionuclide angiography in 20 of 33 patients (61%) (p less than 0.01). Decrease in peak left ventricular filling rate within 10 days of amiodarone therapy (8 of 33 patients) was associated with subsequent sudden death (p less than 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal blood pressure response during exercise in hypertrophic cardiomyopathy

To investigate the incidence of abnormal exercise blood pressure responses in hypertrophic cardiomyopathy (HCM) and the potential role of hemodynamic instability as a mechanism of sudden death, 129 consecutive patients with HCM underwent maximal symptom-limited treadmill exercise testing with blood pressure recording. Four patterns of blood pressure response were observed. Forty-three patients had significant exercise hypotension, with either a continuous fall in systolic blood pressure (n = 5) from the start of exercise or a sudden fall in systolic blood pressure (20-100 mm Hg; mean, 40 mm Hg) from the peak value (n = 38), 23 patients had a normal response during exercise but an abnormal blood pressure response in the recovery period, and the remaining 62 patients demonstrated a normal blood pressure response. Patients with exercise hypotension were younger (33 +/- 14 versus 46 +/- 14 years) and more of them had a family history of HCM and sudden death compared with those with a normal blood pressure response (15 of 43 versus 6 of 62 patients). Similarly, the 23 patients with abnormal recovery blood pressure responses were younger (43 +/- 16 versus 46 +/- 14 years) and had a higher incidence of a family history of sudden death (10 of 24 versus 6 of 62 patients). Left ventricular cavity dimensions were smaller in those with exercise hypotension, but 11 other clinical, echocardiographic, and arrhythmic variables were similar. To assess the mechanism of exercise hypotension, 14 patients who demonstrated exercise hypotension and 14 symptomatic patients with a normal exercise blood pressure response underwent invasive hemodynamic exercise testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in early diastolic filling dynamics after aortic valve replacement

With use of ultrafast computed tomography, 13 patients undergoing aortic valve replacement for aortic stenosis were prospectively followed to evaluate the relation between left ventricular mass and diastolic function. Studies were done before intervention, and then at 4 and 8 months later. Mass decreased from 161 +/- 11 g/m2 (+/- standard error of the mean) at baseline to 106 +/- 5 g/m2, and then to 97 +/- 7 g/m2 at 4 and 8 months, respectively, in 12 patients who demonstrated significant (greater than 20%) mass regression after operation. One patient failed to show significant changes in mass. Diastolic function, as defined by the peak filling rate of early diastole, improved (p less than 0.02) in the group with mass regression, from 2.11 +/- 0.17 s-1 at baseline to 2.12 +/- 0.23 s-1, and then to 2.62 +/- 0.26 s-1 at 4 and 8 months, respectively. Improvement in the time to peak filling rate was also noted. Heart rates were unchanged, whereas end-diastolic volumes decreased and ejection fractions increased slightly. Postoperative increase in peak filling rate correlated with regression of ventricular mass to within normal range (+/- 2 standard deviations) and attainment of New York Heart Association class I status by 8 months (p less than 0.02). Thus, improvement in diastolic function can be seen after aortic valve surgery and is associated with improved functional class. Diastolic function improves later than the regression in wall mass and may imply a delayed remodeling of the ventricle.

Effects of intravenous verapamil on left ventricular relaxation and filling in stable angina pectoris

Left ventricular (LV) diastolic function is often impaired in coronary artery disease (CAD). To assess whether verapamil could improve LV diastolic properties, 12 patients with CAD undergoing right- and left-sided cardiac catheterization, as well as simultaneous radionuclide angiography, were studied before and during intravenous administration of verapamil (0.1 mg/kg as a bolus followed by 0.007 mg/kg/min). The heart rate was kept constant by atrial pacing in both studies. LV pressure-volume relations were obtained. Verapamil decreased LV systolic pressure (130 +/- 22 to 117 +/- 16 mm Hg, p less than 0.01) and the end-systolic pressure/volume ratio (2.4 +/- 1.3 to 1.6 +/- 0.5 mm Hg/ml, p less than 0.05), and increased LV end-diastolic (13 +/- 4 to 16 +/- 4 mm Hg, p less than 0.02) and pulmonary capillary pressures (10 +/- 5 to 12 +/- 5 mm Hg, p less than 0.005). Despite such negative inotropic effects, cardiac index increased (3.4 +/- 0.7 to 3.9 +/- 0.6 liters/min/m2, p less than 0.02). The time constant of isovolumic relaxation shortened (63 +/- 14 to 47 +/- 9 ms, p less than 0.02); peak filling rate increased (370 +/- 155 to 519 +/- 184 ml/s, p less than 0.001; 2.6 +/- 1.1 to 3.3 +/- 0.9 end-diastolic counts/s, p less than 0.02; and 4.1 +/- 1.6 to 5.5 +/- 1.5 stroke counts/s, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nifedipine on left ventricular diastolic function in hypertension; echo Doppler study

Hypertensive cardiac disease shows early alteration of left ventricular diastolic filling, characterized by a longer isovolumetric relaxation period and by an altered E/A ratio on the mitral spectral Doppler. We chose ten hypertensive patients who had left ventricular hypertrophy, but no left ventricular dilatation or mitral valve insufficiency and had a good left ventricular shortening fraction (greater than 26%). After the washout period we studied each of the above-mentioned parameters before and after the acute administration of nifedipine, dinitrate isosorbide, and captopril. While captopril and dinitrate isosorbide induced a prolongation of the isovolumic relaxation time and an impairment of the E/A ratio in mitral spectral Doppler (i.e., left ventricular filling), nifedipine induced an improvement in both parameters. The three drugs also induced a similar reduction in systemic blood pressure values (i.e., similar afterload). We therefore suggest that changes in diastolic function in hypertrophied cardiac fibers, induced by nifedipine, may be the result of a double action: one mediated by hemodynamic changes, the other directly affecting the cellular calcium ion exchange.

Influence of Doppler sample volume location on the assessment of changes in mitral inflow velocity profiles

Previous studies that have validated Doppler indexes of mitral inflow have used pulsed wave sample volume locations either at the level of the mitral valve anulus or at the tips of the mitral valve leaflets. Although significant differences between absolute values for peak velocities and velocity time integrals at these sample volume locations have previously been reported, no information exists that has compared changes in inflow profiles after an intervention to improve left ventricular filling. To address this question, 13 patients with severe pulmonary hypertension (mean pulmonary artery pressure, 50 +/- 13 mm Hg) caused by chronic thromboembolic disease were studied with use of Doppler echocardiography immediately before and after surgical reduction of pulmonary hypertension (pulmonary vascular resistance decreased from 916 +/- 413 to 233 +/- 89 dynes.sec.cm5). This clinical model has been shown to have abnormal mitral inflow velocity profiles that improve markedly after surgery. Doppler measures of early and late peak velocities were significantly lower both before and after surgery when sampling at the mitral anulus compared with the leaflet tips, although late filling parameters and the deceleration of early flow velocity tended to differ little. With surgery, the significant increase in peak early velocity and the ratio of early to late velocity was present regardless of the sample volume location (peak E at leaflet tips, 47.1 +/- 16.0 to 68.9 +/- 15.4 [p less than 0.001], and at anulus, 40.7 +/- 11.3 to 56.2 +/- 14.6 cm/sec [p less than 0.001]; peak E/A at leaflet tips, 0.95 +/- 0.4 to 1.55 +/- 0.9, and at anulus, 0.78 +/- 0.3 to 1.32 +/- 0.7 [both p less than 0.02]).(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of diastolic function by radionuclide ventriculography

Diastolic filling can be measured by radionuclide ventriculography with use of several techniques including those based on gated and list-mode acquisitions, the first-pass method, and the nuclear probe. Radionuclide ventriculography specifically assesses volumes, rates of volume change, and intervals during ventricular filling. Normal values for diastolic filling measurement vary depending on the individual radionuclide methods used and the age of the patient. Comparative studies of the radionuclide method with contrast angiographic and Doppler echocardiographic techniques for measuring diastole are discussed, and the advantages and disadvantages of the radionuclide techniques are explored. The role of radionuclide assessment of diastolic function in specific clinical examples of hypertrophic cardiomyopathy, hypertension, anthracycline-induced cardiomyopathy, and coronary artery disease is reviewed. Radionuclide ventriculography is an accurate and easily applicable procedure for studying left ventricular volume changes in diastole.

Atrial fibrillation in hypertrophic cardiomyopathy: a longitudinal study

The clinical outcome of 52 consecutive patients with hypertrophic cardiomyopathy who developed paroxysmal (less than 1 week) or established (greater than or equal to 1 week) atrial fibrillation between 1960 and 1985 was examined retrospectively and compared with that of a matched group of patients with hypertrophic cardiomyopathy and sinus rhythm. Follow-up study until death or the present ranged from 6 months to 24 years (median 11 years) from diagnosis and from 6 months to 22 years (median 7 years) from the onset of atrial fibrillation. Atrial fibrillation was present in 6 patients at the time of diagnosis, whereas it developed subsequently in 46. The acute onset of arrhythmia was associated with a change in symptoms in 41 (89%) of the 46. After initial treatment of acute atrial fibrillation, sinus rhythm was restored in 29 (63%) of the 46 patients; 43 (93%) of the 46 returned to their original symptom class. Stepwise logistic regression revealed that shorter duration of arrhythmia and amiodarone therapy were the most powerful predictors of return to sinus rhythm. Sinus rhythm was maintained during a median follow-up period of 5.5 years in 22 of the 29 patients in whom it was restored after initial therapy. During follow-up study, 25 of the 52 patients were treated with conventional therapy alone and 7 with amiodarone alone. Amiodarone therapy was associated with maintenance of sinus rhythm, fewer alterations in drug therapy, fewer embolic episodes and fewer attempted direct current cardioversions (during a shorter follow-up period).(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in left ventricular diastolic filling by septal myectomy in hypertrophic cardiomyopathy

Abnormalities in left ventricular diastolic function or filling are considered to be responsible for some of the symptoms in patients with hypertrophic cardiomyopathy. To clarify whether the abnormalities in left ventricular diastolic filling are improved by septal myectomy, 13 patients with hypertrophic cardiomyopathy and intracavitary pressure gradient were studied preoperatively and postoperatively by use of pulsed Doppler echocardiography. Peak early diastolic filling velocity (E), the ratio of peak early diastolic filling to peak atrial filling velocities (E/A ratio), and deceleration time were measured from the transmitral flow velocity pattern before and after septal myectomy. Although E and E/A ratio did not change after septal myectomy, deceleration time significantly shortened from 314 +/- 72 to 271 +/- 53 milliseconds (n = 10; p less than 0.05). Further, if seven patients with significant changes in heart rate (greater than 30%) or in the Doppler-determined severity of mitral regurgitation (more than one degree) were excluded (because these parameters may effect E and E/A ratio), there were also significant changes in E (81 +/- 21 versus 98 +/- 25 cm/sec, p less than 0.05) and in E/A ratio (0.84 +/- 0.17 versus 1.14 +/- 0.33, p less than 0.05). Because left ventricular systolic function has been demonstrated to remain constant or to decrease by most measures after septal myectomy, relief of some symptoms may be largely the result of the improvement in diastolic filling suggested by these criteria.

Syncope in hypertrophic cardiomyopathy: multivariate analysis of prognostic determinants

Twenty-nine consecutive patients with symptomatic hypertrophic cardiomyopathy and a mean age of 44.8 +/- 12.2 years (range 21 to 63) underwent complex invasive and noninvasive testing to identify a risk profile for syncope. Clinical, morphologic, electrophysiologic and hemodynamic variables at rest and at a symptom-limited pacing rate were analyzed for a significant association with syncope. Exact stepwise logistic regression analysis identified three variables as significant independent predictors of syncope in hypertrophic cardiomyopathy: 1) age less than 30 years (beta = 4.803; p = 0.0007); 2) left ventricular end-diastolic volume index less than 60 ml/m2 (beta = 3.302; p = 0.006); and 3) nonsustained ventricular tachycardia on 72 h ambulatory electrocardiographic monitoring (beta = 2.5909; p = 0.03). The combined occurrence of all three variables had a sensitivity and specificity of 100% in identifying eight patients with syncopal events. Thus, the risk for syncope in hypertrophic cardiomyopathy is high in young patients with the combination of low left ventricular filling volume and episodes of nonsustained ventricular tachycardia. This finding might also explain the mechanism of syncope in hypertrophic cardiomyopathy as low input-low output failure induced by a sudden increase in heart rate in the presence of a low filling volume.

Relation between extent of left ventricular hypertrophy and diastolic filling abnormalities in hypertrophic cardiomyopathy

In hypertrophic cardiomyopathy, the relation between left ventricular diastolic impairment and magnitude of left ventricular hypertrophy has not been clearly defined. In the present study, Doppler echocardiographic indexes of left ventricular diastolic filling were compared in 78 patients with hypertrophic cardiomyopathy and in 72 normal control subjects of similar age, and the relation between abnormalities of diastolic filling and magnitude of left ventricular hypertrophy was assessed. In patients with hypertrophic cardiomyopathy, isovolumic relaxation was prolonged (94 +/- 25 ms); peak early diastolic flow velocity (53 +/- 18 cm/s), deceleration of flow velocity in early diastole (341 +/- 142 cm/s2) and the ratio between early and late peaks of flow velocity (1.6 +/- 0.9) were reduced; and peak late diastolic flow velocity was increased (38 +/- 15 cm/s) compared with values in control subjects (76 +/- 12 ms, 65 +/- 12 cm/s, 512 +/- 131 cm/s2, 2.3 +/- 0.8 and 30 +/- 7 cm/s, respectively; p less than 0.001). Individual patient analysis showed that diastolic filling was abnormal in 52 (67%) of the 78 patients with hypertrophic cardiomyopathy. However, within the patient group, none of the Doppler diastolic indexes showed a significant correlation with maximal left ventricular wall thickness or the wall thickness index (correlation coefficients ranged from -0.15 to 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)

Wide-range load shift of combined aortic valvuloplasty-arterial vasodilation slows isovolumic relaxation of the hypertrophied left ventricle

To assess the effects of left ventricular (LV) load on isovolumic relaxation rate of the hypertrophied LV, wide range LV load shifts were imposed by the sequential use of balloon aortic valvuloplasty (BAV) and arterial vasodilation in 14 patients with severe sclerocalcific aortic stenosis (aortic valve area, 0.45 +/- 0.16 cm2). Micromanometer tip-catheter LV pressure recordings (n = 14) and simultaneous LV angiograms (n = 9) were obtained before BAV, during nitroprusside infusion (NIT) before BAV, 48 hours after BAV, and 48 hours after BAV during NIT. LV peak systolic pressure (LVPSP) decreased from 237 +/- 33 mm Hg before BAV to 200 +/- 33 mm Hg (p less than 0.01) during NIT before BAV, to 201 +/- 27 mm Hg (p less than 0.01) after BAV and to 165 +/- 26 mm Hg (p less than 0.01) during NIT after BAV.LV end-systolic volume (LVESV) decreased from 55 +/- 34 ml before BAV to 25 +/- 23 ml (p less than 0.01) during NIT before BAV, to 30 +/- 32 ml (p less than 0.025) after BAV and to 15 +/- 12 ml (p less than 0.025) during NIT after BAV. LV end-systolic wall stress (LVESs) decreased from 90 +/- 30.10(3) dyne/cm2 before BAV to 41 +/- 13.10(3) dyne/cm2 (p less than 0.01) during NIT before BAV, to 55 +/- 16.10(3) dyne/cm2 (p less than 0.025) after BAV and to 26 +/- 6.10(3) dyne/cm2 (p less than 0.01) during NIT after BAV. Only after sequential BAV-NIT was the time of LV electromechanical systole (LVEST), which marked the onset of the LV isovolumic relaxation period, significantly reduced (from 419 +/- 26 msec before BAV to 363 +/- 28 msec after BAV-NIT [p less than 0.01]). The time constants of LV pressure decay with zero or nonzero asymptote pressure (TO and TPB) remained unchanged after BAV and during NIT before BAV. At the lowest LVPSP, LVESV, and LVESs after sequential BAV-NIT, both TO and TPB significantly prolonged from 35.7 +/- 6.3 to 46.7 +/- 12.6 msec (p less than 0.025) and from 46.6 +/- 12.5 to 73.2 +/- 23.3 msec (p less than 0.01). Phase-plane plots (LV dP/dt vs. LVP) of the LV pressure (P) signal during isovolumic relaxation were constructed for the four different loading states by matching corresponding LVP and LV dP/dt points. For a given LVP value, the corresponding LV dP/dt values on the phase plane plots were comparable before BAV, during NIT before BAV, and after BAV. The corresponding LV dP/dt value was higher during NIT after BAV, impling a slower relaxation rate at the same LVP after sequential BAV-NIT. A shift in the control of isovolumic LV relaxation kinetics from myofilamentary detachment to myoplasmic calcium removal, which proceeds slower in hypertrophied myocardium, could explain the observed slowing of LV isovolumic relaxation after drastic LV unloading of sequential BAV-NIT.

Mechanical loads and the isovolumic and filling indices of left ventricular relaxation

In this report we have emphasized the significant influence of loading conditions on LV relaxation. Changes in inotropic state, ischemia, hypertrophy, and a host of other factors were not discussed herein. Ventricular asynchrony is likewise beyond the scope of this review, but it should be recognized that complex loading interactions among fibers within the LV wall influence relaxation and filling in ventricles that contract and relax nonsynchronously. Intact heart and isolated muscle experiments indicate that changes in preload do not influence relaxation rates when systolic pressure or total load remains constant. It appears, therefore, that the relaxation changes that occur with volume loading are primarily due to changes in systolic pressure or load. Indeed, an increase in systolic pressure may cause a substantial decrease in isovolumic relaxation rate, especially if there is a slow rise and a late peak in LV pressure. By contrast, an abrupt increase in late systolic load augments relaxation rate. Intact heart studies indicate that an abrupt load increment near the end of ejection results in premature and more rapid isovolumic relaxation, while an increase in left atrial pressure increases the filling rate; isolated muscle studies indicate that a load increment at the end of isometric relaxation causes an increase in isotonic relaxation rate. Thus, loading conditions during the periods of ejection, isovolumic relaxation, and filling can influence relaxation parameters and should be considered in clinical and experimental studies of LV relaxation.

Prognostic significance of radionuclide-assessed diastolic function in hypertrophic cardiomyopathy

To evaluate the prognostic significance of diastolic function in hypertrophic cardiomyopathy (HC), technetium-99m gated equilibrium radionuclide angiography, acquired in list mode, was performed in 161 patients. Five diastolic indexes were calculated. During 3.0 +/- 1.9 years, 13 patients had disease-related deaths. With univariate analysis, these patients were younger (29 +/- 20 vs 42 +/- 16 years; p less than 0.05), had a higher incidence of syncope (p less than 0.025), dyspnea (p less than 0.001), reduced peak filling rate (2.9 +/- 0.9 vs 3.4 +/- 1.0 end-diastolic volume/s; p = 0.09) with increased relative filling volume during the rapid filling period (80 +/- 7 vs 75 +/- 12%; p = 0.06) and decreased atrial contribution (17 +/- 7 vs 22 +/- 11%; p = 0.07). Stepwise discriminant analysis revealed that young age at diagnosis, syncope at diagnosis, reduced peak ejection rate, positive family history, reduced peak filling rate, increased relative filling volume by peak filling rate and concentric left ventricular hypertrophy were the most statistically significant (p = 0.0001) predictors of disease-related death (sensitivity 92%, specificity 76%, accuracy 77%, positive predictive value 25%). Discriminant analysis excluding the diastolic indexes, however, showed similar predictability (sensitivity 92%, specificity 76%, accuracy 78%, positive predictive value 26%). To obtain more homogeneous groups for analysis, patients were classified as survivors (116) or electrically unstable (40), including sudden death, out-of-hospital ventricular fibrillation and nonsustained ventricular tachycardia during 48-hour ambulatory electrocardiography, and heart failure death or cardiac transplant (5).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nifedipine on left ventricular diastolic function in patients with asymptomatic or minimally symptomatic hypertrophic cardiomyopathy

We investigated the effects of nifedipine on left ventricular diastolic function in 17 asymptomatic or minimally symptomatic patients with hypertrophic cardiomyopathy by simultaneously measuring left ventricular pressure and volume with a catheter-tipped manometer and biplane cineangiography. Studies were performed before and 20 minutes after sublingual administration of nifedipine (20 mg). Heart rates were held constant (79 +/- 12 beats/min, mean +/- SD) by right atrial pacing. Left ventricular volumes and instantaneous rates of left ventricular volume were derived from frame-by-frame (20-msec) analyses of left ventricular biplane angiograms. Left ventricular peak systolic pressure (from 122 +/- 21 to 108 +/- 13 mm Hg, p less than 0.01 vs. control) and mean aortic pressure (from 96 +/- 15 to 87 +/- 11 mm Hg, p less than 0.01) decreased significantly with nifedipine. With afterload reduction, left ventricular ejection fraction (from 0.69 +/- 0.12 to 0.74 +/- 0.08, p less than 0.01) and cardiac output (from 6.4 +/- 2.0 to 7.2 +/- 2.2 l/mm, p less than 0.05) increased significantly. However, there was a slight but significant increase in left ventricular end-diastolic pressure (from 15 +/- 8 to 18 +/- 8 mm Hg, p less than 0.05). Nifedipine did not improve left ventricular relaxation as assessed by the time constants of isovolumic pressure decay (t1/2, from 39.8 +/- 6.6 to 39.4 +/- 7.7 msec, NS; t1/e, from 53.8 +/- 9.0 to 54.4 +/- 10.7 msec, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of diastolic filling indexes obtained by radionuclide ventriculography

This study assesses how differences in residual volume and heart rate influence the measurement and interpretation of commonly used indexes of left ventricular filling obtained by radionuclide ventriculography. Thirty patients with hypertrophic cardiomyopathy (HC) and 26 normal subjects were studied. The time to peak filling rate (168 +/- 42 vs 139 +/- 35 ms; p = 0.006) and time to 30% filling (154 +/- 32 vs 131 +/- 29 ms; p = 0.009 were prolonged in patients with HC compared to normal subjects, suggesting impaired early diastolic filling. However the peak filling rate, measured in end-diastolic counts/s, was greater in patients with HC (3.31 +/- 0.89 vs 3.06 +/- 0.51, p = 0.19). This measurement was influenced by the relative residual volume (HC r = 0.41, p less than 0.001; normal r = 0.29, difference not significant), which was smaller in patients with HC (22.4 +/- 8.0 vs 35.5 +/- 5.6%; p less than 0.0001). The peak filling rate measured in stroke volume counts did not vary with the relative residual volume (HC r = 0.10, difference not significant; normal r = 0.21, difference not significant) and was less than normal in patients with HC (4.27 +/- 0.69 vs 4.72 +/- 1.0; p = 0.58). There was a strong association between the first third filling fraction and the heart rate (HC r = 0.66, p less than 0.001; normal r = 0.71, p less than 0.001), reflecting its dependence on the duration of the first third of diastole.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of temporal smoothing on quantitation of left ventricular function by gated blood pool scintigraphy

Frequently, indexes of systolic and diastolic left ventricular (LV) function obtained from radionuclide angiography are computed after the LV time-activity curve has been temporally smoothed. This smoothing process may introduce important systematic errors into the analysis. To assess this potential effect, high temporal resolution time-activity curves (20 ms/point) were obtained in 113 normal subjects, 175 patients with coronary artery disease and 171 patients with hypertrophic cardiomyopathy. The curves were then subjected to 0-, 3-, 5-, 7- and 9-point temporal smoothing. In each group, increased smoothing progressively and consistently underestimated ejection fraction by up to 5% (p less than 0.001) and peak ejection rate by up to 14% (p less than 0.001). A greater effect on peak filling rate was observed: 5-point and 9-point smoothing reduced peak filling rate by 10% and 23% in normal subjects, 3% and 10% in patients with coronary artery disease and 7% and 15%, respectively, in patients with hypertrophic cardiomyopathy (all p less than 0.001). These errors were compounded further when the same data obtained at lower temporal resolution (40 ms/point) were analyzed: 5-point and 9-point smoothing resulted in underestimation of peak filling rate by 20% and 46% in normal subjects, 13% and 43% in coronary artery disease and 16% and 34% in hypertrophic cardiomyopathy. The underestimation was not uniform, and its magnitude varied considerably among individuals in each of the 3 groups. Thus, smoothing of LV time-activity curves may result in significant systematic errors in computation of indexes of LV systolic and diastolic function, especially in data with poor temporal resolution. These concepts apply to other imaging methods, such as magnetic resonance imaging and cine-computed tomography, that assess LV function from the LV volume curve. Although ejection fraction is affected only mildly by these errors, both peak filling rate and peak ejection rate may be severely underestimated.

Influence of age and sex on left ventricular filling at rest in subjects without clinical cardiac disease

Left ventricular (LV) filling at rest was studied by radionuclide ventriculography using alternate R-wave gating in 42 patients (29 men, 13 women) who had a low likelihood of cardiac disease. LV filling measurements differed little between men and women. Age was correlated positively with atrial filling duration (r = 0.55), atrial filling duration fraction (r = 0.52) and atrial filling fraction (r = 0.56) and negatively with rapid filling fraction (r = -0.58). Age was not correlated with peak filling rate, time to peak filling rate and first-half filling fraction. The heart rate at rest was significantly negatively correlated with rapid (r = -0.62), slow (r = -0.81) and atrial (r = -0.72) filling durations, but not with isovolumic duration. The heart rate at rest was weakly positively correlated with peak filling rate in end-diastolic volume per second (r = 0.36) and negatively correlated with first-half filling fraction (r = -0.35). Systolic pressure at rest influenced atrial filling duration. LV ejection fraction and end-diastolic volume index were not correlated significantly with LV filling in relatively normal subjects.

Subclinical cardiac dysfunction in acromegaly: evidence for a specific disease of heart muscle

Acromegaly is associated with an increased cardiac morbidity and mortality, but it is not clear whether this is the result of increased incidence of hypertension and coronary heart disease or of a specific disease of heart muscle. Thirty four acromegalic patients were studied by non-invasive techniques. Seven of these patients had raised plasma concentrations of growth hormone at the time of study; three were newly diagnosed and had not received any treatment. Hypertension was present in nine (26%) but only three (9%) had electrocardiographic left ventricular hypertrophy. Echocardiography showed ventricular hypertrophy in 12 (48%) and increased left ventricular mass in 17 (68%) patients. Holter monitoring detected important ventricular arrhythmias in 14 patients. Thallium-201 scanning showed evidence for coronary heart disease in eight patients. Systolic time intervals were normal except when there was coexistent ischaemic heart disease. A comparison between 19 acromegalic patients with no other detectable cause of heart disease and 22 age matched controls showed appreciably abnormal left ventricular diastolic function in the group with acromegaly. The abnormalities shown did not correlate with left ventricular mass or wall thickness. There was no difference in diastolic function between patients with active acromegaly and those with treated acromegaly. Hypertensive acromegalic patients had worse diastolic function than hypertensive controls, suggesting that hypertension may further impair the left ventricular diastolic abnormality in acromegaly. This is the first study to find evidence of subclinical cardiac diastolic dysfunction in acromegaly and it supports the suggestion that there is a specific disease of heart muscle in acromegaly.

Effect of the second-generation calcium channel blocking drug nisoldipine on diastolic left ventricular dysfunction in heart failure

The effect of intravenous nisoldipine (0.12 microgram/kg/min) on diastolic left ventricular (LV) dysfunction was studied from simultaneous hemodynamic and radionuclide measurements in 12 patients with New York Heart Association class II to IV cardiac failure. The initial LV filling fraction was low, the peak LV filling rate normalized for end-diastolic volume was decreased, and the pulmonary capillary wedge pressure (PCWP) was high and associated with clinical shortness of breath. Nisoldipine produced an increase in LV filling fraction from 36 +/- 17% to 43 +/- 20% (p = 0.003). The increase in filling took place in both early and late diastole: peak early filling rate (PFR) increased in 11 of the 12 patients (p = 0.02) and late diastolic filling rate (atrial [A] wave in eight of them (NS). When the determinants of these changes, were examined further, it was found that in the control state PFR was inversely related to LV end-systolic volume (r = 0.77), whereas the A wave was related in exponential fashion to PCWP (preload) (r = 0.79). Nisoldipine did not change the slope of these relationships, and it did not alter the end-diastolic pressure-volume relationship, implying that inherent myocardial relaxation and distensibility were unaltered by the drug. In summary, nisoldipine improved measurements of diastolic LV dysfunction in patients with cardiac failure. This study illustrates the importance of considering ventricular loading conditions when analyzing and interpreting measurements of diastolic ventricular dysfunction. The measured changes in diastolic LV function during infusion of nisoldipine appear to be due to alterations in ventricular loading conditions rather than to a direct myocardial effect of the drug.

The effect of acute alterations in left ventricular afterload and beta-adrenergic tone on indices of early diastolic filling rate

The effects of an acute increase in left ventricular systolic pressure and the effects of an intravenous isoproterenol infusion on myocardial (segment) lengthening rate and chamber (minor axis dimension) filling rate were examined in 12 anesthetized dogs. Measurements of left ventricular systolic pressure (by micromanometer) and of segment length and chamber dimension transients (by ultrasonic crystals) were made in variably afterloaded beats (three-beat descending aortic cross-clamp) before and during an isoproterenol infusion that raised (+)dP/dt by 40%. During the baseline state, we found an inverse relation between the peak rate of increase in minor axis dimension [(+)dD/dt] and systolic pressure over a wide range of systolic pressures (110-160 mm Hg) and end-systolic dimensions (25-40 mm); peak (+)dD/dt and end-systolic dimension were also inversely related. During isoproterenol infusion, end-systolic dimension fell from 29.7 +/- 3.1 to 28.0 +/- 3.1 mm and (+)dD/dt increased from 79.6 +/- 8.0 to 90.1 +/- 8.7 mm/sec; however, the slope and y intercept of the relation between (+)dD/dt and end-systolic dimension were unchanged. Peak (+)dD/dt at a common end-systolic dimension of 31 mm was nearly equal during baseline and isoproterenol states (64.2 +/- 6.3 vs. 65.1 +/- 6.6 mm/sec). Similar results were found using segment length transients. We interpret these data to indicate that (+)dD/dt is strongly influenced by changes in systolic pressure and dimension and that isoproterenol-induced changes in (+)dD/dt are mediated, at least in part, through changes in systolic pressure and dimension.

Comparative effects of verapamil and nitroprusside on left ventricular function in patients with hypertension

The effects of verapamil were compared with those of nitroprusside at matched mean arterial pressures and heart rates in 10 symptomatic hypertensive patients during cardiac catheterization. Simultaneous radionuclide angiography and micromanometer pressure measurements were obtained to assess left ventricular pressure-volume relations. Compared with control conditions, verapamil increased left ventricular end-diastolic volume index from 57 +/- 16 to 70 +/- 28 ml/m2 (p = 0.05) without a significant increase in left ventricular end-diastolic pressure (from 10 +/- 4 to 13 +/- 6 mm Hg). Despite a downward and rightward shift in the end-systolic pressure-volume relation indicating negative inotropic effects, ejection fraction did not decrease significantly (from 52 +/- 9% to 46 +/- 9%); cardiac index and stroke volume index remained unchanged. The change in stroke volume index with verapamil was directly related to the magnitude of change in end-diastolic volume index (r = 0.82, p less than 0.005), suggesting that the increase in end-diastolic volume did not arise purely from negative inotropic effects. Systemic vascular resistance index decreased from 42 +/- 8 to 34 +/- 7 mm Hg.min.m2/liter (p less than 0.05). In contrast, nitroprusside decreased left ventricular end-diastolic volume index from 57 +/- 16 to 41 +/- 10 ml/m2 (p less than 0.05), cardiac index from 3.2 +/- 0.7 to 2.8 +/- 0.6 liters/min per m2 (p less than 0.05) and stroke volume index from 28 +/- 6 to 24 +/- 5 ml/m2 (p less than 0.01), with no change in systemic vascular resistance index (40 +/- 10 mm Hg.min.m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Verapamil. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension

Although verapamil is a well-established treatment for angina, cardiac arrhythmias and cardiomyopathies, this review reflects current interest in calcium antagonists as anti-hypertensive agents by focusing on the role of verapamil in hypertension. Verapamil is a phenylalkylamine derivative which antagonises calcium influx through the slow channels of vascular smooth muscle and cardiac cell membranes. By reducing intracellular free calcium concentrations, verapamil causes coronary and peripheral vasodilation and depresses myocardial contractility and electrical activity in the atrioventricular and sinoatrial nodes. Verapamil is well suited for the management of essential hypertension since it produces generalised systemic vasodilation resulting in a marked reduction in systemic vascular resistance and, consequently, blood pressure. Evidence from clinical studies supports the role of oral verapamil as an effective and well-tolerated first-line treatment for the management of patients with mild to moderate essential hypertension. Clinical studies have shown that verapamil is more effective the higher the pretreatment blood pressure and some authors have found a more pronounced antihypertensive effect in older patients or in patients with low plasma renin activity. Sustained release verapamil formulations are available for oral administration which, as a single daily dose, are as effective in lowering blood pressure over 24 hours as equivalent doses of conventional verapamil formulations given 3 times daily. As a first-line antihypertensive agent, oral verapamil is equivalent to several other calcium antagonists, beta-blockers, diuretics, angiotensin-converting enzyme (ACE) inhibitors and other vasodilators, and is not associated with many of the common adverse effects of these treatments. Verapamil may be preferred as an alternative first-line antihypertensive treatment to diuretics in elderly patients because it has similar efficacy in these patients without causing the adverse effects commonly linked with diuretic treatment. Furthermore, because verapamil does not cause bronchoconstriction, it may be used in preference to beta-blockers in patients with asthma or chronic obstructive airway disease. Reflex tachycardia, orthostatic hypotension or development of tolerance is not evident following verapamil administration. As a second- or third-line treatment for patients refractory to established antihypertensive regimens, verapamil produces marked blood pressure reductions when combined with diuretics and/or ACE inhibitors, beta-blockers and vasodilators such as prazosin.(ABSTRACT TRUNCATED AT 400 WORDS)

Determinants of exercise capacity in hypertrophic cardiomyopathy

Exercise capacity in hypertrophic cardiomyopathy is thought to relate to elevated left atrial pressure as a consequence of impaired diastolic function, but this assumption has not previously been evaluated. Twenty-three patients with hypertrophic cardiomyopathy underwent hemodynamic assessment during symptom-limited maximal exercise with objective measurement of exercise capacity by respiratory gas analysis. Maximal oxygen consumption and anaerobic threshold were 28.1 +/- 7.5 and 21.5 +/- 6.1 ml/kg per min, respectively (the lower limit of reference range in our laboratory is 39 and 27 ml/kg per min, respectively). Maximal oxygen consumption was reduced in 11 of 13 patients who were in New York Heart Association functional class I and who denied limitation of exercise capacity and in all 10 patients who were in functional class II or III. Maximal oxygen consumption and anaerobic threshold were related to peak cardiac index (r = 0.650, p less than 0.001 and r = 0.459, p = 0.03, respectively) and to the increase in cardiac index on exercise (r = 0.677, p less than 0.001 and r = 0.509, p = 0.016, respectively), but not to cardiac index at rest, peak and rest pulmonary capillary wedge pressure, pulmonary capillary wedge pressure at an oxygen consumption of 15 ml/kg per min or the rise in pulmonary capillary wedge pressure on exercise. These findings are not consistent with the hypothesis that elevated left atrial pressure is the major determinant of exercise capacity in patients with hypertrophic cardiomyopathy and they suggest that, as in patients with chronic cardiac failure, other mechanisms should be considered.

The significance of increased left ventricular outflow tract velocities in the elderly measured by continuous wave Doppler

Forty-four elderly patients (mean age 80 +/- 7 years) with elevated left ventricular outflow tract velocities and corresponding outflow tract gradients documented by continuous wave Doppler are reported (mean peak gradient 50 +/- 28). They had severe left ventricular hypertrophy, small left ventricular end-diastolic dimensions, and supernormal ejection fractions. Thirty-nine percent had a history of hypertension. They were predominantly female, had uniform concentric left ventricular hypertrophy, and had a high incidence of congestive heart failure. Diastolic function was found to be reduced in the elderly group compared to young patients with hypertrophic cardiomyopathy and to age- and sex-matched normal controls. It is concluded that most elderly patients with increased left ventricular outflow tract velocities are etiologically distinct from young patients with hypertrophic cardiomyopathy.

Effects of a single dose of isosorbide-5-mononitrate on the left ventricular diastolic function in systemic hypertension

The effect of a single dose of isosorbide-5-mononitrate on left ventricular (LV) diastolic function was assessed by radionuclide ventriculography in 18 hypertensive patients. The effect of the mononitrate on atrial filling also was assessed. As expected, there was a significant decrease in mean blood pressure (120 +/- 17 to 102 +/- 18 mm Hg, p less than 0.005). Global LV ejection fraction did not show a significant change, increasing slightly from 64 +/- 9 to 68 +/- 8% (difference not significant). The mononitrate prolonged the time to peak filling rate from 176 +/- 36 to 195 +/- 29 ms (p less than 0.0001). The percentage of time to peak filling rate from diastole also increased, from 46 to 53% (p less than 0.05), whereas the normalized peak filling rate did not change (2.36 +/- 0.6 to 2.31 +/- 0.6 end-diastolic volumes/s, difference not significant). This effect on LV diastolic function was closely related to a certain reduction in preload, as suggested by the reduction in mean left atrial filling (45 +/- 12 to 40 +/- 13 counts/s, p less than 0.005) and LV diastolic counts, suggesting that the "impairment" of diastolic function induced by nitrates is secondary to the reduction in venous return to the left atrium. The mononitrate did not affect the mean right atrial filling rate (50 +/- 12 to 52 +/- 13 counts/s) and the right ventricular end-diastolic counts, suggesting a primary vasodilatory effect of nitrates on the pulmonary vascular bed.

The challenge of cardiomyopathy

The combined clinical and pathophysiologic characteristics and diagnostic features as well as current concepts of pathogenesis, therapy and prevention of the principal forms of cardiomyopathy are reviewed. These include hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy and specific cardiac muscle disease. Emphasis is placed on recent developments and unresolved questions requiring application of newer techniques of molecular biology and genetics and adult myocyte culturing.

Myocardial stunning in hypertrophic cardiomyopathy: recovery predicted by single photon emission computed tomographic thallium-201 scintigraphy

A young woman with hypertrophic cardiomyopathy confirmed by echocardiography and cardiac catheterization presented with chest pain and features of a large left ventricular aneurysm. The initial diagnosis was myocardial ischemia with either an evolving or an ancient myocardial infarction. Subsequently, verapamil therapy was associated with complete resolution of the extensive left ventricular wall motion abnormalities, normalization of left ventricular ejection fraction and a minimal myocardial infarction. Normal thallium uptake on single photon emission computed tomographic scintigraphy early in the hospital course predicted myocardial viability in the region of the aneurysm. Thus, orally administered verapamil may reverse spontaneous extensive myocardial ischemia in hypertrophic cardiomyopathy and possibly limit the extent of myocardial infarction in such circumstances.

Verapamil prevents silent myocardial perfusion abnormalities during exercise in asymptomatic patients with hypertrophic cardiomyopathy

Recent studies indicate that reversible 201Tl perfusion defects, compatible with silent myocardial ischemia, commonly develop during exercise in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM). To determine whether this represents a dynamic process that may be modified favorably by medical therapy, we studied 29 asymptomatic or minimally symptomatic patients with HCM, aged 12-55 years (mean, 28), with exercise 201Tl emission computed tomography under control conditions and again after 1 week of oral verapamil (mean dosage, 453 mg/day). Treadmill time increased slightly during verapamil (21.0 +/- 3.6 to 21.9 +/- 2.7 minutes, p less than 0.005), but peak heart rate-blood pressure product was unchanged (26.3 +/- 6.0 X 10(3) compared with 25.0 +/- 6.4 X 10(3). Two midventricular short-axis images per study were divided into five regions each, and each of these 10 regions was then analyzed on a 0-2 scale by three observers blinded with regard to the patients' therapy. Average regional scores of 1.5 or less were considered to represent perfusion defects, and a change in regional score of 0.5 or more was considered to constitute a significant change. During control studies, 15 patients (52%) developed perfusion defects with exercise (average, 3.7 regions per patient). In 14 of these patients, all perfusion defects completely reversed after 3 hours of rest; one patient had fixed defects. After administration of verapamil, exercise perfusion scores improved in 10 of the 14 patients (71%) with reversible defects; there was overall improvement in 34 of 50 (68%) regions with initially reversible perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)