Effect of acute volume loading on diastolic function in hypertrophic cardiomyopathy

ABSTRACT

To evaluate left ventricular [LV] diastolic function in hypertrophic cardiomyopathy [HCM], we studied pulsed Doppler parameters, isovolumic relaxation time index [IVRT interval from minimum LV dimension to mitral valve opening] and LV end-diastolic volume and mass [using the area-length method and apical 4-chamber 2D-echocardiography]. Doppler indices included E/A ratio, deceleration [Dec] and peak filling rate [PFR]. Measurements [mean +/- SE] were obtained in 16 patients with HCM, age 47 +/- 3y, and 8 normal subjects [46 +/- 3y, p NS] at rest and after a rapid IV infusion of IL saline. IVRT [msec] was significantly longer in HCM 58 = 6 compared to normal 40 +/- 6, P. However, resting Doppler measurements were not significantly different in HCM and normal groups, respectively E/A 0.9 +/- 0.07 vs 1.2 +/- 0.16 Dec 284 +/- 31 vs 330 +/- 50 cm/sec2, PER 449 +/- 72 vs 366 +/- 46 ml/sec. We divided the patients into 2 groups HCM-A, n = 6, type III [Maron et al. classification] hypertrophy involving 2 segments of LV by 2D-echocardiography; HCM-B, n = 10, types I, II or apical hypertrophy involving relaxation but it was slightly and insignificantly prolonged in HCM-B group. Saline infusion induced all increase in LV diastolic fining in the normal group [increase in Dec from 330 +/- 50 to 435 +/- 39 cm/sec3, P and in PFR, P] as well as in HCM-B group [increase in E/A from 0.88 +/- 0.08 to 1.2 +/- 0.1, P]. In contrast, preload augmentation resulted in impairment of diastolic filling in HCM-A [E/A declined from 0.96 +/- 0.12 to 0.78 +/- 0.07, p]. The latter group had a smaller LV volume/mass ratio after saline, P than HCM-B group. Resting Doppler indices of LV diastolic function were not significantly different in HCM and an age matched normal group. However, HCM patients comprise a heterogenous group. Patients with more extensive hypertrophy had evidence of slow relaxation at rest and an abnormal diastolic fining pattern in response to volume loading