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[The influence of increase in heart rate on coronary flow dynamics in the patients with aortic stenosis]
T Fujiwara1, H Masaki, H Yamane
1Department of Thoracic Surgery, Kawasaki Medical School.
Insights
Effort angina in aortic stenosis is linked to reduced diastolic coronary flow. Isoproterenol infusion improved coronary inflow, unlike atrial pacing, offering insights into managing angina in these patients.
Area of Science:
- Cardiovascular Physiology
- Cardiac Surgery
- Hemodynamics
Context:
- Aortic stenosis significantly impacts left ventricular workload and coronary circulation.
- Understanding the mechanisms of effort angina in aortic stenosis is crucial for patient management.
- Phasic left coronary flow velocity is a key indicator of myocardial perfusion.
Purpose:
- To investigate the effects of increased heart rate on coronary blood flow in aortic stenosis.
- To differentiate the impact of atrial pacing versus isoproterenol infusion on coronary flow dynamics.
- To identify interventions that can improve diastolic coronary inflow in aortic stenosis.
Summary:
- In aortic stenosis, coronary flow velocity waveforms show slow diastolic inflow and delayed peak velocity.
- Atrial pacing to increase heart rate reduced diastolic coronary flow due to shortened filling time.
- Isoproterenol infusion accelerated diastolic inflow and increased peak velocity, significantly enhancing coronary blood supply.
Impact:
- This study highlights the differential effects of heart rate modulation on coronary perfusion in aortic stenosis.
- Findings suggest isoproterenol may be beneficial in augmenting coronary flow and potentially alleviating effort angina.
- Provides critical data for surgical and pharmacological strategies in managing aortic stenosis patients with angina.
Abstract:
To clarify the causative factors responsible for the development of effort angina in aortic stenosis, the influence of an increase in heart rate by atrial pacing and isoproterenol infusion on the phasic left coronary flow velocity waveforms were studied using a pulsed Doppler velocimeter during cardiac surgery. Coronary flow velocity waveforms in aortic stenosis was characterized by a slowly increased diastolic inflow and an elongation of the time from the onset of diastole to the diastolic peak velocity. An increase in heart rate by pacing brought about a marked decrease in diastolic coronary flow since the slowly increasing diastolic flow was cut with the onset of following systole. On the contrary, after an increase in heart rate by infusion of isoproterenol, diastolic increasing rate in the coronary flow waveform accelerated and diastolic peak velocity markedly increased. As the results, isoproterenol produced a significant increase in diastolic coronary inflow.