The evolution of cardiac resynchronization therapy and an introduction to conduction system pacing: a conceptual
Bengt Herweg1,2, Allan Welter-Frost1,2, Pugazhendhi Vijayaraman3
1Division of Cardiovascular Sciences, University of South Florida Morsani College of Medicine, South Tampa Center, 2 Tampa General Circle, Tampa, FL 33606, USA.
Insights
Cardiac resynchronization therapy (CRT) improves heart failure outcomes, but limitations exist. Conduction system pacing (CSP) shows promise as a physiologic alternative to conventional CRT for better patient response.
Area of Science:
- Cardiology
- Biomedical Engineering
Background:
- Cardiac resynchronization therapy (CRT) is a key non-pharmacologic treatment for chronic systolic heart failure and conduction system disease.
- Conventional bi-ventricular pacing offers benefits but has variable clinical success due to factors like myocardial scar and fibrosis.
Purpose of the Study:
- To systematically review the evolution of CRT.
- To introduce conduction system pacing (CSP) as a potential physiologic alternative to conventional CRT.
Main Methods:
- Systematic review of existing literature on CRT evolution.
- Review of observational and acute hemodynamic studies on conduction system pacing (CSP).
Main Results:
- Conventional CRT limitations include scar, fibrosis, and ineffective simulation of diseased tissue.
- Endocardial stimulation near the conduction system is more effective than epicardial stimulation.
- Studies indicate improved electrical resynchronization and echocardiographic response with CSP.
Conclusions:
- Conduction system pacing (CSP) presents an intriguing, albeit experimental, physiologic approach to cardiac resynchronization.
- CSP may overcome limitations of conventional CRT, potentially offering improved patient outcomes.
Abstract:
In chronic systolic heart failure and conduction system disease, cardiac resynchronization therapy (CRT) is the only known non-pharmacologic heart failure therapy that improves cardiac function, functional capacity, and survival while decreasing cardiac workload and hospitalization rates. While conventional bi-ventricular pacing has been shown to benefit patients with heart failure and conduction system disease, there are limitations to its therapeutic success, resulting in widely variable clinical response. Limitations of conventional CRT evolve around myocardial scar, fibrosis, and inability to effectively simulate diseased tissue. Studies have shown endocardial stimulation in closer proximity to the specialized conduction system is more effective when compared with epicardial stimulation. Several observational and acute haemodynamic studies have demonstrated improved electrical resynchronization and echocardiographic response with conduction system pacing (CSP). Our objective is to provide a systematic review of the evolution of CRT, and an introduction to CSP as an intriguing, though experimental physiologic alternative to conventional CRT.
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