Pacing tachycardia exaggerates left ventricular diastolic dysfunction but not systolic function and regional asynergy or asynchrony in patients with hypertrophic cardiomyopathy.
OBJECTIVE
Myocardial ischaemia and angina have been demonstrated in patients with hypertrophic cardiomyopathy (HCM). We hypothesized that left ventricular (LV) systolic or diastolic dysfunction would be provocated by pacing tachycardia in patients with HCM.


RESULTS
We investigated LV global and regional systolic and diastolic function in 17 patients with HCM without LV outflow obstruction and 7 normal subjects by analysing LV angiograms and simultaneously obtained high-fidelity LV pressures before and after rapid cardiac pacing (150 b.p.m.). Biplane LV silhouettes were digitized frame by frame (50 frames/s). To quantify regional dynamics, the ventricular area of the right anterior oblique projection was divided into six sections originating from the midpoint of the long axis at end-diastole. There were no significant changes in LV function after pacing in normal subjects. In HCM, the ejection fractions remained unchanged. However, LV end-diastolic pressures rose (+12 mmHg, P < 0.01), and the time constants of isovolumic pressure decay were significantly increased (T(1/2): +5.2 ms, P < 0.01; T(1/)(e): +6.8 ms, P < 0.01). The LV global diastolic pressure-volume relationships and regional diastolic pressure-area relationships of regional myocardium shifted upward (indicating decreased diastolic distensibility) in all patients. These diastolic abnormalities were not accompanied by regional asynchrony or asynergy.


CONCLUSIONS
Most patients with HCM have a reduced reactive capacity to chronotropic stress, which is haemodynamically characterized by evenly distributed diastolic dysfunction. In contrast with coronary artery disease, these diastolic abnormalities were not accompanied by systolic dysfunction, regional asynchrony, asynergy, or inhomogenous diastolic distensibility.
Tarumi
Toshiaki
T
Department of Cardiology, Mie University of Medicine, Tsu, Mie, Japan.
Takebayashi
Shigeto
S
Fujita
Masatoshi
M
Nakano
Takeshi
T
Ito
Masaaki
M
Yamakado
Tetsu
T
D000328:Adult; D000368:Aged; D002304:Cardiac Pacing, Artificial; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology*; D003971:Diastole / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D013599:Systole / Q000502:physiology*; D018487:Ventricular Dysfunction, Left; D055815:Young Adult