Echocardiographic analysis of ventricular septal dynamics in hypertrophic cardiomyopathy and other diseases

Regional left ventricular contractile dynamics in hypertrophic cardiomyopathy evaluated by magnetic resonance imaging

To assess regional myocardial function in hypertrophic cardiomyopathy (HCM), we examined systolic wall thickening (%WT) and percent change of segmental wall area (%AR) by cine magnetic resonance imaging. We studied 23 normal volunteers without evidence of heart disease (group 1) and 40 patients with HCM (group 2). Short-axis images of the left ventricle were recorded at the base and the apex, and were divided into five segments. There were no significant differences in %WT and %AR among the segments in group 1, while %WT and %AR at the apex were higher than values for corresponding segments at the base. The patients with HCM (group 2) were classified into three groups according to end-diastolic wall thickness: group 2a, less than 12 mm; group 2b, 12-15 mm and group 2c, greater than 15 mm. Both the %WT and %AR at the base were significantly higher in group 2a than in the other groups, but were significantly lower in group 2c than in group 1 or group 2a (%WT and %AR in groups 1, 2a, 2b, and 2c respectively: 51 +/- 29 and 19 +/- 17; 83 +/- 40 and 34 +/- 18; 47 +/- 38 and 16 +/- 14; and 32 +/- 21 and 9 +/- 8). Both %WT (40 +/- 24) and %AR (14 +/- 12) at the apex were significantly lower in group 2c than in the other groups (87 +/- 45 and 38 +/- 31 in group 1; 89 +/- 41 and 39 +/- 31 in group 2a; and 61 +/- 27 and 24 +/- 15 in group 2b). Myocardial shortening in the normal volunteers was greater at the apex than at the base. In patients with HCM, regional myocardial function was decreased in association with the degree of hypertrophy, with the wall function of the normal segments appearing to be increased in a possible compensatory mechanism.

Phasic coronary flow characteristics in patients with hypertrophic cardiomyopathy: a study by coronary Doppler catheter

Abnormal patterns of coronary flow velocity have been observed in patients with symmetric left ventricular hypertrophy in conditions such as aortic stenosis and systemic hypertension. However, phasic coronary flow characteristics have not been investigated in patients with asymmetric left ventricular hypertrophy in hypertrophic cardiomyopathy. The purpose of this study was to assess phasic coronary flow characteristics and their relation to echocardiographic and hemodynamic parameters in patients with hypertrophic cardiomyopathy. Coronary flow velocity was recorded in the left anterior descending artery with a 20 MHz Doppler catheter in eight patients with hypertrophic nonobstructive cardiomyopathy and eight control subjects with normal coronary arteries. Flow reversals observed in systole in all patients with hypertrophic cardiomyopathy, and the time velocity integrals of systolic flow were significantly smaller in patients with hypertrophic cardiomyopathy than in control subjects (-1.5 +/- 1.7 versus 4.3 +/- 1.2 cm; p < 0.01). The time from the beginning of diastole to peak diastolic velocity corrected by the square root of R-R interval (square root of RR) was prolonged significantly, and the velocity half-time from peak diastolic velocity corrected by square root of RR was shorter in the patients with hypertrophic cardiomyopathy compared with those in the control subjects (6.8 +/- 2.0 msec versus 4.0 +/- 0.6 msec [p < 0.01] and 9.2 +/- 4.9 msec versus 13.9 +/- 2.0 msec [p < 0.05], respectively). Peak velocity and time velocity integral of flow reversal showed significant correlations with anterior ventricular septal thickness (y = -0.5x + 13.5, r = 0.8, and p < 0.01; y = -1.3 +/- 16.8, r = 0.8, and p = 0.024, respectively), the septal/free wall thickness ratio (y = -0.1x + 1.1, r = 0.8, and p < 0.01; y = -0.2x + 1.4, r = 0.9, and p < 0.01, respectively), and the degree of narrowing of the first septal perforator arteries (y = 1.9x + 91.6, r = 0.8, and p = 0.012; y = 6.1x + 80.6, r = 0.9, and p < 0.01, respectively). In conclusion, flow reversal in systole and slow acceleration and rapid deceleration in diastole were characteristics in patients with hypertrophic cardiomyopathy. Flow reversal might be related to the degree of left ventricular asymmetry and compression of the septal perforator arteries.

Morphological determinants of echocardiographic patterns of mitral valve systolic anterior motion in obstructive hypertrophic cardiomyopathy

BACKGROUND

The morphological determinants of mitral valve systolic anterior motion (SAM) and obstruction to left ventricular outflow in patients within the broad clinical spectrum of hypertrophic cardiomyopathy (HCM) are not completely understood, particularly the contribution of mitral leaflet length and size.

METHODS AND RESULTS

To clarify this issue, mitral valve specimens from 43 patients with HCM and basal outflow obstruction were used to relate morphometric measurements of leaflet area to certain morphological and functional assessments of left ventricular outflow tract geometry and valvular motion obtained from echocardiograms in the same patients. Twenty-four patients (56%) had mitral valves of normal size (leaflet area < 12.0 cm2) and 19 patients (44%) had enlarged and elongated valves (area > or = 12.0 cm2). Compared with normal-sized mitral valves, the enlarged valves were situated more posteriorly in a larger left ventricular outflow tract (cross-sectional area, 3.3 +/- 1.0 versus 1.9 +/- 0.7 cm2 for normal-sized valves; p < 0.001) and also had greater systolic excursion of the anterior leaflet (16.2 +/- 4.5 versus 13.3 +/- 3.3 mm, p < 0.02), usually with a distinctive sharp-angled bend and localized contact of the leaflet tip with ventricular septum ("typical" SAM); this pattern of SAM was possible because the central and distal portions of the leaflet were relatively free of fibrous thickening. In contrast, normal-sized mitral valves were situated more anteriorally in a smaller left ventricular outflow tract and frequently showed a different mechanism of SAM and subaortic obstruction with relatively limited leaflet motion, absence of a sharp bend, and septal contact involving more substantial portions of the anterior leaflet and contiguous chordae ("atypical" SAM); mitral-septal apposition was effected in large measure by posterior ventricular septal motion. This pattern of SAM was invariably associated with a more diffuse pattern of fibrous thickening.

CONCLUSIONS

Patients with obstructive HCM show patterns of mitral valve SAM that are diverse and determined largely by the interrelation of left ventricular outflow tract geometry, the size and mobility of the mitral leaflets, and the presence and distribution of fibrous thickening.

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)

Postextrasystolic potentiation of systolic gradient in valvular aortic stenosis: clinical usefulness and analysis of hemodynamic factors

To analyze the behavior of aortic valve gradient (AVG) after ventricular extrasystole (VE), we studied 36 pure valvular aortic stenoses (AS) free of coronary artery disease and obstructive hypertrophic cardiomyopathy, in whom basal (B) (74 +/- 32 mm Hg) and catheter-induced post-VE (110 +/- 50 mm Hg) AVG were obtained. In all 26 cases with valve area less than 0.70 cm2, the post-VE AVG was greater than or equal to 70 mm Hg. In 19 cases AVG after two or more consecutive VE were also obtained. Maximal post-VE AVG was obtained after multiple VE (19 cases) and/or after one VE causing a post-VE pause equal or longer than 1.7 basal cardiac cycles (post-VE RR greater than or equal to 1.7 B RR) (9 cases). Basal and postsingle VE AVG, up to a post-VE RR greater than or equal to 1.7 B RR, were a linear function of previous RR (r greater than or equal to 0.90), regression line slope increasing with AS severity (P = .05). Inotropic state measured by PEP/LVET only increased after multiple VE, P less than .01. AVG after multiple VE was independent of post-VE RR. Thus, 1) post-VE potentiation of AVG may be seen with fixed valvular AS without obstructive cardiomyopathy; 2) post-VE AVG is a function of compensatory pause after single VE and of increased inotropism after multiple VE; 3) analysis of maximal post-VE AVG generated as described is reliable and useful for assessing AS severity (post-VE AVG greater than or equal to 70 mm Hg meaning an aortic valve area less than 0.70 cm2) and may supplement valve area calculations.

Hypertrophic cardiomyopathy with extreme increase in left ventricular wall thickness: functional and morphologic features and clinical significance

Clinical and morphologic features of 34 patients with hypertrophic cardiomyopathy and particularly marked left ventricular hypertrophy were analyzed. Only patients with a ventricular septal thickness of at least 35 mm (range to 52 mm) were selected for the study; 31 (90%) had a diffuse pattern of hypertrophy also involving substantial portions of the left ventricular free wall. Despite similar left ventricular morphology, these patients exhibited a broad spectrum of clinical findings and natural history. Ten patients (29%) had hemodynamic or echocardiographic evidence of basal subaortic obstruction (average gradient, 63 mm Hg); however, the majority (24 [71%]) had no evidence of obstruction at rest, despite substantial hypertrophy of the basal anterior portions of septum and free wall. Although the electrocardiograms of most patients (76%) showed patterns of left ventricular hypertrophy, the magnitude of precordial QRS complexes was not markedly increased (S wave in lead V1 or V2, 27 +/- 15 mm; R wave in lead V5 or V6, 21 +/- 9 mm). The clinical course was variable in 30 patients who were followed up for at least 1 year (mean 6 years). Although no patient died, nine (30%) have exhibited clinical deterioration, including two who spontaneously developed complete heart block and one who collapsed with ventricular fibrillation but survived. However, the clinical condition of the majority of patients (21 [70%]) remained unchanged or improved. At the most recent evaluation, 20 (67%) of the 30 patients were asymptomatic or only mildly symptomatic, including 7 who remained without symptoms throughout the period of follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)