Circulation, Vol 84, 1496-1504, Copyright © 1991 by American Heart Association
W Hayashida, T Kumada, F Kohno, M Noda, N Ishikawa, J Kojima, Y Himura and C Kawai
BACKGROUND. Regional nonuniformity has been suggested to be closely related
to left ventricular (LV) relaxation in diseased heart. The purpose of the
present study was to assess LV global and regional relaxation in patients
with nonobstructive hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS.
Left ventriculography was conducted simultaneously with pressure
micromanometry in 10 normal control subjects and 11 patients with
nonobstructive HCM. LV silhouettes in the right anterior oblique projection
were divided into eight regions, and regional wall stress during isovolumic
relaxation was computed for six regions from the midventricle to the apex.
In HCM patients, isovolumic relaxation time (IRT) and the time constant of
LV pressure decrease (Tp) were greater than in control subjects (IRT, 84
+/- 13 versus 66 +/- 6 msec; Tp, 51 +/- 8 versus 36 +/- 5 msec,
respectively; p less than 0.01). In HCM patients, the (-)dP/dt upstroke
pattern was convex- downward, and dP/dt(20/60), the ratio of dP/dt values
20 and 60 msec after peak (-)dP/dt, was less than in control subjects (1.46
+/- 0.16 versus 2.15 +/- 0.14, p less than 0.01). These findings suggest
that there is impaired LV relaxation in HCM patients. End-systolic regional
wall stress was lower, and the time constant of regional stress decrease
(Tst) was prolonged for each region in HCM patients compared with control
subjects. In the HCM group, Tst tended to be more prolonged in regions with
increased wall thickness than in regions with normal wall thickness (60 +/-
15 versus 50 +/- 11 msec, p less than 0.01). The coefficient of variation
for Tst values in six areas of the left ventricle was calculated in each
subject and was greater in HCM patients than in control subjects (13 +/- 7%
versus 7 +/- 3%, p less than 0.05), indicating regional nonuniformity in
Tst during isovolumic relaxation in HCM patients. CONCLUSIONS. Significant
correlations existed between the coefficients of variation for Tst and Tp
(r = 0.80, p less than 0.01), IRT (r = 0.79, p less than 0.01), and
dP/dt(20/60) (r = -0.67, p less than 0.05) in the HCM group. Thus, regional
nonuniformity is closely related to the impairment of LV relaxation in HCM.
ARTICLES
Left ventricular regional relaxation and its nonuniformity in hypertrophic nonobstructive cardiomyopathy
Department of Internal Medicine, Faculty of Medicine, Kyoto University, Japan.
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