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Relation between the pacing induced sequence of activation and left ventricular pump function in animals
Frits W Prinzen1, Maaike Peschar
1Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands. Frits.Prinzen@FYS.uni-maas.NL
Pacing and Clinical Electrophysiology : PACE
|May 7, 2002
Summary
Ventricular pacing causes asynchronous electrical activation, impairing heart pump function. Optimizing pacing sites is crucial for improving cardiac function in patients.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Mechanics
Background:
- The Purkinje system facilitates rapid ventricular activation during normal sinus rhythm and atrial pacing.
- Ventricular pacing bypasses the Purkinje system, leading to asynchronous and abnormal ventricular electrical activation through the myocardium.
- This abnormal activation disrupts regional systolic function, mechanical work, blood flow, and oxygen consumption.
Purpose of the Study:
- To review animal experimental data on the impact of asynchronous ventricular activation on cardiac pump function.
- To investigate how different ventricular pacing sites affect left ventricular (LV) function.
- To understand the mechanisms underlying the depression of LV function during abnormal electrical activation.
Main Methods:
- Review of animal experimental studies examining ventricular pacing and cardiac function.
- Analysis of data comparing LV function under various pacing conditions (e.g., right ventricular apex, high ventricular septum, LV sites).
- Investigation of hearts with experimentally induced Left Bundle Branch Block (LBBB).
Main Results:
- Ventricular pacing, particularly at the right ventricular apex, significantly depresses systolic and diastolic LV function.
- Pacing at the high ventricular septum or LV sites results in less depression of LV function compared to the RV apex.
- In canine hearts with LBBB, LV pacing markedly improves LV pump function.
- The depression in LV function is attributed to a combination of activation asynchrony and abnormal sequence, not solely QRS duration.
Conclusions:
- Asynchronous ventricular activation induced by pacing impairs cardiac pump efficiency.
- Optimizing the site of ventricular pacing is essential for preserving or improving LV function in patients.
- Further research and clinical attention are warranted to determine optimal pacing strategies for diverse patient populations.