ABNORMAL CORONARY FLOW DYNAMICS AT REST AND DURING TACHYCARDIA ASSOCIATED WITH IMPAIRED LEFT-VENTRICULAR RELAXATION IN HUMANS - IMPLICATIONFOR TACHYCARDIA-INDUCED MYOCARDIAL-ISCHEMIA
T. Masuyama et al., ABNORMAL CORONARY FLOW DYNAMICS AT REST AND DURING TACHYCARDIA ASSOCIATED WITH IMPAIRED LEFT-VENTRICULAR RELAXATION IN HUMANS - IMPLICATIONFOR TACHYCARDIA-INDUCED MYOCARDIAL-ISCHEMIA, Journal of the American College of Cardiology, 24(7), 1994, pp. 1625-1632
Objectives. This study attempted to clarify the effect of ventricular
relaxation abnormalities on coronary dow dynamics at rest and during t
achycardia in humans. Background. Ventricular relaxation abnormality h
as been demonstrated in animals to have an adverse impact on early dia
stolic coronary flow dynamics. However, this relation has not been est
ablished in humans. Even if the adverse effect were latent at rest, it
might become evident during tachycardia because tachycardia reduces c
oronary flow reserve and facilitates the production of myocardial isch
emia. Methods. Doppler phasic left coronary flow velocity pattern was
obtained at rest and during tachycardia in 23 patients without coronar
y stenosis. The time constant of left ventricular isovolumic pressure
(tau) was used to assess ventricular relaxation. Results. The time to
peak flow velocity of the diastolic coronary flow wave was longer, and
the fraction of the first third of diastolic coronary how was smaller
, in patients with a longer tau (r = 0.58, p < 0.01; r = -0.44, p < 0.
05), indicating a close relation between early diastolic coronary flaw
dynamics and ventricular relaxation. Although rapid atrial pacing yie
lded an increase in the coronary how velocity integral per minute in a
ll patients, diastolic coronary how velocity integral per minute incre
ased in 9 patients with a normal (less than or equal to 40 ms) tau at
rest but decreased in 14 patients with a longer (>40 ms) tau at rest.
Conclusions. Impaired left ventricular relaxation was associated with
decreased coronary flow in early diastole at rest and decreased corona
ry flow throughout diastole during tachycardia in patients without cor
onary stenosis. These findings may provide more insight into the mecha
nism of tachycardia-induced subendocardial docardial ischemia in patie
nts with impaired ventricular relaxation but without concomitant coron
ary stenosis.