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Ventricular performance in relation to heart rate and AV delay at rest
1Department of Cardiology, University of Erlangen-Nürnberg, Germany.
European Heart Journal
|November 1, 1992
Summary
Heart rate and AV delay significantly impact cardiac function differently across heart conditions. Understanding these effects is crucial for managing heart failure patients and optimizing cardiac pacing strategies.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Heart rate (HR) and atrioventricular delay (AVD) are critical determinants of cardiac output and ventricular filling.
- Different heart diseases, including coronary heart disease (CHD), hypertensive heart disease (HHD), and dilated cardiomyopathy (DCM), may alter the hemodynamic response to changes in HR and AVD.
Purpose of the Study:
- To investigate the distinct influences of heart rate and AV delay on left ventricular hemodynamics in patients with CHD, HHD, DCM, and healthy controls.
- To quantify the impact of pacing variations on cardiac index, ejection fraction, and ventricular volumes and pressures.
Main Methods:
- Utilized the conductance catheter technique in 12 patients (CHD, HHD, DCM, controls).
- Measured hemodynamic parameters across a range of pacing rates (80-180 bpm) and AV delays (0-240 ms).
- Employed 3-D linear regression analysis to model the effects of HR and AVD on hemodynamic variables for each patient group.
Main Results:
- Increased HR raised cardiac index without altering ejection fraction in controls, but decreased them in HHD and DCM. CHD patients showed constant cardiac index.
- CHD patients exhibited elevated left ventricular end-diastolic pressure (LVEDP) with higher HR, alongside decreased left ventricular end-diastolic volume (LVEDV) and stroke volume.
- In HHD, longer AVD increased LVEDV and decreased LVEDP and left ventricular end-systolic volume (LVESV), improving the stroke volume to LVEDP ratio. DCM showed a similar trend for SV/LVEDP but lacked significant AVD influence on LVEDP.
Conclusions:
- The hemodynamic response to alterations in heart rate and AV delay is highly dependent on the underlying cardiac pathology.
- Optimizing AV delay may offer therapeutic benefits in managing heart failure patients, particularly those with HHD and DCM, by improving ventricular filling and output efficiency.
- These findings highlight the importance of individualized pacing strategies based on specific cardiac conditions to enhance left ventricular performance.
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