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Do acute changes in heart rate by isoproterenol affect aortic stiffness in patients with hypertension?
Moo-Yong Rhee1, Na-Young Kwon, Jae-Deok Kim
1Department of Internal Medicine, College of Medicine, Dankook University, Cheonan, Korea. rheemy@dankook.ac.kr
Insights
Acute changes in heart rate (HR) from isoproterenol do not significantly affect aortic stiffness in hypertensive patients. This suggests HR variations are not critical when measuring aortic pulse wave velocity (PWV).
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Vascular Mechanics
Background:
- Increased aortic stiffness is a key risk factor for cardiovascular disease in hypertensive individuals.
- Previous studies indicated heart rate (HR) changes during pacing do not impact aortic stiffness.
- The effect of sympathomimetic-induced acute HR changes on aortic stiffness in hypertension remains unclear.
Purpose of the Study:
- To investigate the impact of acute heart rate (HR) alterations induced by isoproterenol on aortic stiffness.
- To determine if acute HR changes influence aortic stiffness measurements in patients with hypertension.
Main Methods:
- Seventeen hypertensive patients participated after discontinuing vasoactive drugs.
- Carotid-to-femoral pulse wave velocity (PWV) was measured using the foot-to-foot method.
- PWV, compliance (C), and compliance index (Ci) were assessed at baseline and with incremental isoproterenol doses to increase HR; percent changes (delta) were analyzed.
Main Results:
- No significant differences were observed in deltaPWV, deltaC, or deltaCi across groups based on HR changes (p > 0.05).
- Regression analysis revealed no significant correlation between deltaHR and deltaPWV or deltaC (r = 0.18, 0.13; p > 0.05).
- A weak correlation was found between deltaHR and deltaCi (r = 0.22, p < 0.05), explaining only 4.6% of the variance (r² = 0.046).
Conclusions:
- Acute changes in heart rate (HR) induced by isoproterenol do not significantly alter aortic stiffness in hypertensive patients.
- These findings suggest that acute HR variations do not necessitate consideration during aortic pulse wave velocity (PWV) measurements.
- Aortic stiffness assessment via PWV may be reliable despite acute HR fluctuations in hypertensive individuals.
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).
Conclusion:
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.
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