Do acute changes in heart rate by isoproterenol affect aortic stiffness in patients with hypertension?
BACKGROUND
Increased aortic stiffness is a independent risk factor of cardiovascular disease in patients with hypertension. Acute changes of the heart rate (HR) have been reported not to affect the aortic stiffness in pacing. However, it is unknown whether acute changes in HR caused by sympathomimetics can affect the aortic stiffness in patients with hypertension. We investigated the effect of acute changes in HR produced by isoproterenol on the aortic stiffness in 17 hypertensive patientss (mean age: 59 +/- 9 years).


METHODS
All vasoactive drugs were discontinued at least 3 days before the study. The carotid-to-femoral pulse wave velocity (PWV) was measured by the foot-to-foot method. The pulse waves were recorded at the baseline and at every increase of HR by 5 to 10 bpm with a gradual increase of the dose of isoproterenol. The blood pressures and HR were measured simultaneously. For the analysis, HR, PWV, compliance (C), and compliance index (Ci) were converted as percent changes (delta) from the baseline values. Percent changes of the parameters of the aortic stiffness, i.e., deltaPWV, deltaC, and deltaCi, were grouped by every 10% increase in deltaHR.


RESULTS
There was no significant difference among groups in deltaPWV, deltaC and deltaCi (p > 0.05 for each of the group). The regression analysis showed no significant correlation of deltaHR with deltaPWV and deltaC (r = 0.18, 0.13 respectively, p > 0.05 for each). deltaCi had a poor correlation with deltaHR (r = 0.22, p < 0.05). However, only 4.6% of deltaCi could be referred to deltaHR (r2 = 0.046).


CONCLUSIONS
Aortic stiffness was not affected by acute changes in HR produced by isoproterenol which suggests that it is not necessary to consider acute changes in HR when measuring aortic PWV.
Rhee
Moo-Yong
MY
Department of Internal Medicine, College of Medicine, Dankook University, Cheonan, Korea. rheemy@dankook.ac.kr
Kwon
Na-Young
NY
Kim
Jae-Deok
JD
Song
Seung-Ho
SH
Yoon
Young-Won
YW
Lee
Myoung-Yong
MY
Kim
Young-Kwon
YK
D000368:Aged; D001011:Aorta / Q000187:drug effects*; D002637:Chest Pain / Q000209:etiology; D003327:Coronary Disease / Q000150:complications; D004548:Elasticity / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000503:physiopathology*; D007545:Isoproterenol / Q000494:pharmacology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011673:Pulsatile Flow / Q000502:physiology; D013566:Sympathomimetics / Q000494:pharmacology*
D013566:Sympathomimetics; D007545:Isoproterenol