Circulation, Vol 51, 689-700, Copyright © 1975 by American Heart Association
MA Quinones, WH Gaasch, JS Cole and JK Alexander
The time course of left ventricular (LV) circumferential stress and fiber
shortening velocity (Vcf) were determined at 20 msec intervals in 30
patients from simultaneous recordings of LV pressure (micromanometer) and
LV dimensions (echography). In 12 patients with normal LV function,
endocardial and midwall maximal (max) Vcf, Vcf at peak stress, and
endocardial mean Vcf were significantly greater than in eight patients with
myocardial disease. Peak stress was less in the normal subjects (mean equal
241 gl/cm2, range 180 to 310 g/cm2) than in those with myocardial diseases
(mean equals 371 g/cm2, range 280 to 513 g/cm2). Vcf was reduced in five
out of seven patients with chronic LV volume overload, while peak stress
ranged from normal in three to increased in four. Max Vcf, mean Vcf, and
peak stress were normal in three patients with chronic LV pressure
overload; Vcf at peak stress was normal in two. Good correlation was
observed between angiographic determinations of mean Vcf and endocardial
max Vcf, Vcf at peak stress and mean Vcf. Induced changes in preload in
five patients (dextran infusion at constant heart rate) produced a 12.2 per
cent increase in peak stress (P small than 0.05), and insignificant changes
in max Vcf (3.7 per cent increase, P = NS), in Vcf at peak stress (5 per
cent decrease, P smaller than 0.05), in mean Vcf (0.7 per cent increase, P
= NS). Increasing afterload with angiotensin in seven patients (peak stress
increased by 45 per cent, P smaller than 0.01) reduced max Vcf, Vcf at peak
stress and mean Vcf by 33 per cent, 39 per cent respectively. Lowering
afterload in one patient (amyl nitrite) produced an increase in Vcf.
Improvement in Vcf was observed in all instances during positive inotropic
stimulation (isoproterenol in three normals, digoxin in four with
myocardial disease). Thre response of endocardial and midwall Vcf to
loading and contractility were similar. In man Vcf is an index of
myocardial contractility which is affected minimally by changes in preload
but responds inversely to changes in afterload. Its sensitivity to acute
afterload changes may, at times, limit its clinical applicability.
ARTICLES
Echocardiographic determination of left ventricular stress-velocity relations
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