Relation between marked changes in left ventricular outflow tract gradient and disease progression in hypertrophic cardiomyopathy

Spontaneous and persistent changes in left ventricular (LV) outflow gradient have been observed occasionally in patients with hypertrophic cardiomyopathy (HC). However, the significance and frequency of such hemodynamic alterations have not been established. In this study, the serial preoperative hemodynamic status of 409 patients with HC was analyzed. Basal LV outflow tract obstruction either spontaneously appeared (or increased) or disappeared (or decreased) in 19 nonoperated patients (about 5%). Changes in hemodynamic state were shown by serial cardiac catheterization in 17 patients and by catheterization and M-mode echocardiography in 2 patients. In most patients (12 of 19), subaortic obstruction under basal conditions appeared or increased; 8 became more symptomatic and in 4 the condition remained stable. Reduction or loss of LV outflow gradient occurred in 7 patients; in 5 of these the condition deteriorated clinically and in 2 it did not change. Hence, in 13 of the 19 patients (70%), spontaneous changes in the magnitude of the basal LV outflow gradient were associated with symptomatic progression. The mechanism of the decrease or disappearance of subaortic obstruction in those patients who deteriorated clinically appeared to be related in 4 patients to impaired global and/or segmental LV function. Chronic atrial fibrillation probably contributed to the worsening clinical condition in 2 of these patients as well as in 2 others. In conclusion, substantial changes in the magnitude of basal subaortic obstruction may occur in a small proportion of patients with HC as part of the natural history of their disease, and such hemodynamic alterations are usually associated with clinical deterioration. It is exceedingly rare for the hemodynamic state of a patient with HC to change from totally nonobstructive to obstructive or vice versa, because such patients usually retain the capacity to generate gradients with provocative maneuvers.

Optimum fourier filtering of cardiac data: a minimum-error method: concise communication

Random fluctuations limit the accuracy of quantities derived from cardiac time-activity curves (TACs). To overcome this problem, TACs are often fitted with a truncated Fourier series giving rise to two sources of error: (a) the truncated series may not adequately describe the TAC shape, causing errors in parameters calculated from the fit: and (b) successive TACs acquired from the same subject under identical circumstances will fluctuate due to limited counts, causing the Fourier fits (and parameters derived from them) to fluctuate. These two errors, respectively, decrease and increase as the number of harmonics increases, suggesting the existence of a minimum in total error. This number of harmonics for minimum error (NHME) was calculated for each of six common parameters used to describe LV TACs. The "true" value of each parameter was determined from TACs of very high statistical precision. Poisson noise was added to simulate lower count rates. For low-count TACs, use of either a smaller or a larger number of harmonics resulted in significantly greater error. NHME was found to occur at two harmonics for the systolic parameters studied, regardless of the noise level present in the TAC. For diastolic parameters, however, NHME was a strong function of the noise present in the TAC, varying from three harmonics for noise levels typical of regional TACs, to five or six harmonics for high-count global TACs.

The acute and chronic effects of verapamil on left ventricular function in patients with hypertrophic cardiomyopathy

Verapamil therapy improves exercise tolerance and decreases symptoms in many patients with both obstructive and nonobstructive forms of hypertrophic cardiomyopathy. These salutory clinical effects result from favorable modification by verapamil of the pathophysiologic abnormalities in left ventricular function characteristic of this disease: impaired early diastolic relaxation and filling, reduced end-diastolic volume and stroke volume, hypercontractile systolic function, and, in many patients, subvalvular outflow tract obstruction. The acute administration of intravenous verapamil produces both significant negative inotropic effects and significant effects on left ventricular diastolic function, resulting in reduced contractile state, diminished outflow gradient, increased end-diastolic volume and stroke volume and improved relaxation and diastolic filling. In some patients, one effect may predominate over the other, and improved diastolic function may be masked by the profound changes in systolic function. During short-term oral therapy, enhanced diastolic function is the predominant effect, although negative inotropic mechanisms are evident in some patients. These effects on left ventricular systolic and diastolic function persist during chronic oral verapamil therapy, contributing to the long-term clinical improvement experienced by many patients.

Effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy: pressure-volume analysis with a nonimaging scintillation probe

To investigate the effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy, we studied 14 patients at catheterization with a nonimaging scintillation probe before and after serial intravenous infusions of low-, medium-, and high-dose verapamil (total dose 0.17 to 0.72 mg/kg). Percent change in radionuclide stroke counts after verapamil correlated well with percent change in thermodilution stroke volume (r = .87), and changes in diastolic and systolic counts were used to assess relative changes in left ventricular volumes after verapamil. Verapamil produced dose-related increases in end-diastolic counts (19 +/- 9% increase; p less than .001), end-systolic counts (91 +/- 54% increase; p less than .001), and stroke counts (7 +/- 10% increase; p less than .02). This was associated with a decrease in ejection fraction (83 +/- 8% control, 73 +/- 10% verapamil; p less than .001) and, in the 10 patients with left ventricular outflow tract gradients, a reduction in gradient (62 +/- 27 mm Hg control, 32 +/- 35 mm Hg verapamil; p less than .01). The end-systolic pressure-volume relation was shifted downward and rightward in all patients, suggesting a negative inotropic effect. In 10 patients, left ventricular pressure-volume loops were constructed with simultaneous micromanometer pressure recordings and the radionuclide time-activity curve. In five patients, verapamil shifted the diastolic pressure-volume curve downward and rightward, demonstrating improved pressure-volume relations despite the negative inotropic effect, and also increased the peak rate of rapid diastolic filling. In the other five patients, the diastolic pressure-volume relation was unaltered by verapamil, and increased end-diastolic volumes occurred at higher end-diastolic pressures; in these patients, the peak rate of left ventricular diastolic filling was not changed by verapamil. The negative inotropic effects of intravenous verapamil are potentially beneficial in patients with hypertrophic cardiomyopathy by decreasing left ventricular contractile function and increasing left ventricular volume. Verapamil also enhances left ventricular diastolic filling and improves diastolic pressure-volume relations in some patients despite its negative inotropic effect.

Assessment of regional left ventricular function by sector analysis: a method for objective evaluation of radionuclide blood pool studies

Regional wall motion abnormalities are most often detected visually, and hence subjectively, in gated blood pool studies of the heart. Therefore, an automated method was developed to objectively assess regional left ventricular (LV) function. The method was tested in 26 normal volunteers and 29 patients with angiographically proved coronary artery disease. Fifteen patients with coronary artery disease had a normal LV ejection fraction (EF) at rest, and all had an abnormal EF response with exercise; 23 had visual regional wall motion abnormalities with rest or exercise. The left ventricle was divided into 28 sectors that radiated from the LV center of gravity, with 1 region at the LV center. A time-activity curve was generated for each sector and the EF and Fourier phase were computed from each curve. Rest and exercise sector EF versus sector number plots were superimposed and the area difference between these 2 curves was taken as an index of regional contraction. Similarly, an estimator of sector phase differences, obtained from the plot of phase versus sector number, was taken as an index of wall motion asynchrony. Analysis of the reliability of these 2 indexes suggests that this automated technique has at least the same efficiency as subjective evaluation of gated blood pool studies, but possesses the advantage of objectivity. The technique may also be useful in localizing regional defects and, perhaps, in detecting mild abnormalities not readily perceived visually.

Prospective evaluation of doxorubicin-induced cardiomyopathy resulting from postsurgical adjuvant treatment of patients with soft tissue sarcomas

One hundred and one soft tissue sarcoma patients from an adjuvant chemotherapy study of the Surgery Branch, National Cancer Institute who had received greater than or equal to 430 mg/m2 (range, 430-600 mg/m2) of doxorubicin were followed for evidence of cardiomyopathy. Fourteen patients developed clinical congestive heart failure attributable to doxorubicin. Nine of these fourteen were evaluated by radionuclide angiography (RNA), and all were abnormal with mean ejection fraction both at rest and exercise less than 30%. Sixty-one asymptomatic patients were studied at least once with RNA. In this asymptomatic group, 13 of 61 patients (21%) had abnormal resting left ventricular function. Exercise studies identified an additional 19 abnormal individuals (31%). Overall incidence of cardiomyopathy, as evidenced by RNA, in the asymptomatic group was 52%. By including the fourteen symptomatic patients, the incidence of cardiomyopathy detected either clinically or by RNA in the 75 evaluated patients was 46%. Comparison of patients by age (less than 40 versus greater than 40) revealed a highly significant difference in the incidence of cardiomyopathy (P less than .001). Fourteen of 36 patients (38%) less than or equal to 40 had either clinical or RNA evidence of cardiotoxicity while 32 of 39 (82%) individuals greater than 40 demonstrated cardiomyopathy. No significant difference was seen in those asymptomatic patients in whom RNA was performed less than or equal to 12 months as compared with greater than 12 months after the end of doxorubicin treatment. In the entire group there was no apparent improvement in cardiomyopathy with time, but results suggest that left ventricular function in the group older than 40 years does deteriorate. The cardiac function of patients younger than age 40 appeared to remain stable or possibly improve with time after the completion of treatment. Sex, tumor location, and radiation treatment were not associated with an increased risk of cardiomyopathy. These results emphasize the dangers of full-dose doxorubicin therapy. This high incidence of cardiomyopathy became apparent because of our ability to prospectively evaluate a large group of patients with prolonged life expectancy that received adjuvant doxorubicin chemotherapy after surgery.

Prevalence and significance of an abnormal S-T segment response to exercise in a young athletic population

Treadmill stress electrocardiography is employed widely to detect underlying cardiovascular disease in asymptomatic persons. To determine the frequency and significance of an abnormal S-T segment response to exercise in young athletes with increased left ventricular (LV) mass induced by physical conditioning, 75 male isometrically trained athletes without evidence of heart disease (mean age 21 years) and 48 nonathletic young normal subjects were studied by M-mode echocardiography and exercise electrocardiography. Ventricular septal and posterior free wall thicknesses and calculated LV mass were significantly greater in athletes than in control subjects. An abnormal S-T segment response to exercise was present in 7 (9%) of the 75 athletes, all of whom had a LV mass greater than 275 g and in 5 the LV mass was above the 95th percentile of that of the control subjects. An abnormal treadmill exercise test result also was present in 3 (6%) of 48 control subjects. Seven of the 10 subjects with abnormal exercise test results had radionuclide angiograms at rest and with exercise, each of which was normal. It is concluded, therefore, that (1) abnormal exercise test results occur commonly in both athletes and non-athletes; (2) almost 10% of isometrically trained athletes have "false-positive" exercise electrocardiograms, suggesting that this test has major limitations in screening for underlying cardiovascular disease in athletes; and (3) in athletes, a relation was present between "physiologically" increased LV mass and false-positive exercise test results.

Atrial systole and left ventricular filling in hypertrophic cardiomyopathy: effect of verapamil

Many patients with hypertrophic cardiomyopathy (HC) have impaired left ventricular (LV) rapid diastolic filling. To quantitate the contribution of atrial systole to LV filling, we used radionuclide angiography to study 30 normal volunteers and 42 patients with HC before and after oral administration of verapamil (320 to 560 mg/day). LV time-activity curves were constructed by combined forward and reverse gating from the R wave, and the onset of atrial systole was determined by the P-R interval. The percent of LV stroke volume filled during rapid diastolic filling and atrial systole was then computed. Peak LV filling rate during rapid diastolic filling was expressed in end-diastolic volume (EDV)/second. Peak rate of rapid diastolic filling was not different in normal patients and those with HC (3.3 +/- 0.6 versus 3.3 +/- 1.1 EDV/s) and was within the normal range in 34 patients with HC (81%). However, the contribution to LV filling volume by rapid diastolic filling was diminished in patients with HC (83 +/- 7% normal, 67 +/- 17% HC, p less than 0.001) and the contribution of atrial systole was increased (16 +/- 8% normal, 31 +/- 18% HC, p less than 0.001). LV filling volume during atrial systole was above the upper normal limit of 31% in 17 patients (40%), including 13 patients with a normal peak filling rate. After verapamil, peak filling rate increased (to 4.2 +/- 1.2 EDV/s, p less than 0.001), percent LV filling during rapid diastolic filling increased (to 83 +/- 7%, p less than 0.001), and percent LV filling during atrial systole decreased (to 16 +/- 9%, p less than 0.001). Percent LV filling volume during atrial systole was abnormal after verapamil in only 3 patients (7%). Hence, although the peak rate of rapid diastolic filling may be normal in patients with HC, the contribution to LV filling by rapid diastolic filling is reduced and that of atrial systole is thereby increased. Increased rate and magnitude of rapid diastolic filling during verapamil is associated with decrease and normalization of the contribution of atrial systole to LV filling. These data suggest that many patients with HC are at risk of hemodynamic decompensation with the onset of atrial fibrillation or other tachyarrhythmias and loss of the atrial contribution to LV filling. This risk may be reduced during verapamil therapy.

Improved left ventricular diastolic filling in patients with coronary artery disease after percutaneous transluminal coronary angioplasty

Left ventricular (LV) diastolic filling is abnormal at rest in many patients with coronary artery disease (CAD), even in the presence of normal resting LV systolic function. To determine the effects of improved myocardial perfusion on impaired. LV diastolic filling, we studied 25 patients with one-vessel CAD by high-temporal-resolution radionuclide angiography before and after percutaneous transluminal coronary angioplasty (PTCA). No patient had ECG evidence of previous myocardial infarction. Despite normal regional and global LV systolic function at rest in all patents, LV diastolic filling was abnormal (peak LV filling rate [PFR] less than 2.5 end-diastolic volumes (EDV)/sec or time to PFR greater than 180 msec) in 17 of 25 patients. Twenty-three patients had abnormal LV systolic function during exercise. After successful PTCA, LV ejection fraction and heart rate at rest were unchanged, but LV ejection fraction during exercise increased, from 52 +/- 8% (+/- SD) to 63 +/- 5% (p less than 0.001). LV diastolic filling at rest improved: PFR increased from 2.3 +/- 0.6 to 2.8 +/- 0.5 EDV/sec (p less than 0.001) and time to PFR decreased from 181 +/- 22 to 160 +/- 18 msec (p less than 0.001). Thus, a reduction in exercise-induced LV systolic dysfunction after PTCA, reflecting a reduction in reversible ischemia, was associated with improved LV diastolic filling at rest. These data suggest that in many CAD patients with normal resting LV systolic function and without previous infarction, abnormalities of resting LV diastolic filling are not fixed, but appear to be reversible manifestations of impaired coronary flow.

Prospective randomized study of the role of N-acetyl cysteine in reversing doxorubicin-induced cardiomyopathy

We conducted a randomized prospective trial in 19 disease-free soft tissue sarcoma patients with doxorubicin-induced cardiomyopathy identified by ECG radionuclide angiography at rest and during exercise to determine the efficacy of the free radical scavenger, N-Acetyl Cysteine (NAC), in reversing the drug's cardiotoxic effect. Of the 19 patients, 11 received oral NAC (5.5 gm/m2 daily for 30 days) and eight patients served as controls. Patients were stratified for age less than greater than 45 years, time from final dose of doxorubicin to randomization less than greater than 8 months, and history of treatment with mediastinal irradiation. The two groups were well-matched for all parameters. Cumulative mean doxorubicin dose (523 mg/m2 and 532 mg/m2) and range 500-600 mg/m2 was comparable. Left ventricular (LV) ejection fraction before randomization was not significantly different between the two groups either at rest (39 +/- 10% control, 38 +/- 13% NAC) or during exercise (38 +/- 12% control, 35 +/- 11% NAC). Neither rest nor exercise ejection fraction values changed significantly in either group between prerandomization and 1-month postrandomization studies. Late studies performed in seven NAC patients 3-5 months after randomization revealed no difference in LV ejection fraction compared to 1-month postrandomization values. Clinical course in patients with overt congestive heart failure was similar in both groups. LV function did not return to normal in any patient in either group. We conclude that N-Acetyl Cysteine has no effect in reversing long standing doxorubicin-induced cardiomyopathy.

Timing of operation for chronic aortic regurgitation

Left ventricular systolic function is an important determinant of long-term prognosis in patients with chronic aortic regurgitation. Data from several centers, using invasive and noninvasive assessment of left ventricular function, indicate that long-term postoperative survival is excellent, even in symptomatic patients, if preoperative left ventricular systolic function is normal. The long-term postoperative results are significantly worse in symptomatic patients with preoperative left ventricular systolic dysfunction, many of whom appear to have irreversible left ventricular failure before the onset of symptoms and are at a risk of late postoperative death from congestive heart failure. However, within this high risk subgroup long-term prognosis is excellent for patients, despite left ventricular dysfunction, if preoperative exercise capacity is preserved. In these patients, left ventricular dysfunction is likely to be reversible after operation. Hence, all patients with left ventricular dysfunction at rest should undergo aortic valve replacement, even if severe symptoms and deterioration in exercise tolerance have not developed. Once exercise tolerance becomes limited in such patients, the likelihood of irreversible left ventricular dysfunction is increased, and long-term postoperative survival is threatened.

Hypertrophic cardiomyopathy with ventricular septal hypertrophy localized to the apical region of the left ventricle (apical hypertrophic cardiomyopathy)

Clinical and morphologic features are described in a unique subgroup of seven patients with hypertrophic cardiomyopathy. Five patients either died suddenly or are alive but severely symptomatic. In each patient ventricular septal hypertrophy was demonstrated on two dimensional echocardiography or at necropsy to be virtually confined to its apical one-half. However, conventional M mode echocardiography was unreliable in identifying this site of hypertrophy because it was often inaccessible to the path of the M mode beam. Apical distribution of septal hypertrophy does not constitute a separate disease entity, but rather appears to be part of the morphologic spectrum of hypertrophic cardiomyopathy, as judged from two findings: (1) genetic transmission of hypertrophic cardiomyopathy in relatives of each study patient; and (2) marked disorganization of cardiac muscle cells in the left ventricular wall of the two patients studied at necropsy. Apical distribution of septal hypertrophy in these patients was associated with relatively mild T wave inversion in the electrocardiogram and characteristic angiographic appearance of the left ventricle with mid ventricular constriction and a small, often poorly contractile apical segment. These electrocardiographic and angiographic features differ from those previously described in Japanese patients with "apical hypertrophic cardiomyopathy" in whom "giant" T wave inversion and a "spade-like" appearance of the left ventricle were characteristic.

Effects of verapamil and propranolol on left ventricular systolic function and diastolic filling in patients with coronary artery disease: radionuclide angiographic studies at rest and during exercise

To determine the effects of verapamil on left ventricular (LV) systolic function and diastolic filling in patients with coronary artery disease (CAD), we performed gated radionuclide angiography at rest and during exercise in 16 symptomatic patients before and during oral verapamil therapy (480 mg/day). Twelve patients were also studied during oral propranolol (160--320 mg/day). LV ejection fraction at rest was normal in 13 patients, but abnormal diastolic filling at rest, defined as peak filling rate (PFR) less than 2.5 end-diastolic volumes (EDV)/sec or time to PFR greater than 180 msec, was present in 15. During verapamil, resting ejection fraction decreased (control 50 +/- 10% [+/- SD), verapamil 45 +/- 12%, p less than 0.005), but resting diastolic filling improved: PFR increased (control 1.9 +/- 0.6 EDV/sec, verapamil 2.3 +/- 0.9 ECV/sec, p less than 0.005) and time to PFR decreased (control 185 +/- 38 msec, verapamil 161 +/- 27 msec, p less than 0.05). Exercise ejection fraction did not change during verapamil (control 42 +/- 13%, verapamil 43 +/- 12%, NS), but exercise PFR increased (control 3.1 +/- 0.9 EDV/sec, verapamil 3.6 +/- 1.1 EDV/sec, p less than 0.05) and exercise time to PFR decreased (control 108 +/- 30 msec, verapamil 91 +/- 17 msec, p less than 0.05). In contrast, propranolol did not alter ejection fraction, PFR, or time to PFR at rest or during exercise. Thus, LV ejection fraction is decreased by verapamil at rest but is unchanged during exercise. While LV systolic function is not improved by verapamil, LV diastolic filling is enhanced by verapamil, both at rest and during exercise. These mechanisms may account in part for the symptomatic improvement in many patients during verapamil therapy.

A method for objective evaluation of functional images

A method is described for characterizing functional maps by means of a frequency distribution function (DF) of pixels. The method makes use of a map of the standard deviation of the functional parameter. By use of this map the method (a) becomes less sensitive to imprecise definition of the organ borders, (b) compensates for random fluctuations in the functional map, and (most importantly) (c) permits spatial information to be included in the DF. This spatial information is included by performing spatial cluster weighting--a procedure that emphasizes regional dysfunction over global dysfunction. The method is illustrated by applying it to phase maps of the left ventricle. In this example, it is shown that analysis of the DF permits detection of regional abnormalities of LV wall motion and that an improvement in detectability is obtained with cluster weighting.

Improved myocardial function during exercise after successful percutaneous transluminal coronary angioplasty

Fifty-nine consecutive patients with coronary-artery disease undergoing percutaneous transluminal coronary angioplasty were evaluated with radionuclide ventriculography at rest and during exercise before angioplasty (when possible) and afterward when it was successful. Thirty-eight patients (64 per cent) had an angiographically successful procedure. Three (5 per cent) had coronary occlusion as a complication. Arterial stenosis was reduced from 74 +/- 2 per cent to 31 +/- 3 per cent (mean +/- S.E.M.). The mean ejection fraction was 55 +/- 2 per cent at rest and 51 +/- 3 per cent during exercise before the procedure. After successful angioplasty, the ejection fraction was unchanged at rest but increased to 62 +/- 2 per cent (P less than 0.001) during exercise. Regional dysfunction was present during exercise in 94 per cent of the patients before the procedure and in only 8 per cent after successful angioplasty. Of the 38 patients in whom the procedure was successful, 19 had sustained improvement for over six months, and eight for three to six months. Eleven patients had recurrence of symptoms; the second angioplasty was initially successful in nine. In 24 patients remaining asymptomatic for six months (19 after the first procedure and five after the second), the left ventricular ejection fraction during exercise remained stable or improved.

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

Verapamil improves exercise capacity in patients with hypertrophic cardiomyopathy (HCM), but its mechanism of action are unknown. We examined the effects of oral verapamil (320-480 mg/day) on resting left ventricular (LV) systolic and diastolic function in patients with HCM. High-temporal-resolution time-activity curves from gated technetium-99m radionuclide angiograms were analyzed before and after verapamil therapy in 40 patients, of whom 16 were also studied during propranolol therapy (80-960 mg/day). All but one patient had normal or supranormal systolic function, but 70% had evidence of diastolic dysfunction, defined as peak LV filling rate (PFR) less than 2.5 end-diastolic volumes (EDV)/sec or time to PFR greater than 80 msec. Verapamil did not change LV ejection fraction, peak ejection rate or ejection time, but did increase PFR (control 3.3 +/- 1.0 EDV/sec, verapamil 4.1 +/- 1.1 EDV/sec; p less than 0.001) and reduce time to PFR (control 187 +/- 56 msec, verapamil, 159 +/- 34 msec; p less than 0.001). Only 30% of patients had evidence of diastolic dysfunction during verapamil. In contrast, propranolol did not change LV ejection fraction, PFR or time to PFR, but did prolong ejection time and reduce peak ejection rate. Thus, LV diastolic filling is abnormal in a high percentage of patients with HCM, and verapamil normalizes or improves these abnormalities without altering systolic function. This mechanism may contribute to the clinical improvement of many HCM patients during verapamil therapy.