Left ventricular endocardial pacing for CRT

Left ventricular endocardial pacing for CRT

Left ventricular endocardial pacing for CRT: Cardiac resynchronization therapy (CRT) is now an established mode of therapy for heart failure with ejection fraction below 35%, QRS width above 120 msec and NYHA class III or more. Conventionally, left ventricular pacing in CRT is achieved by epicardial pacing, either through the coronary veins or direct access by thoracotomy. Left ventricular endocardial pacing has not been very popular because of the difficulty in pacing by trans septal approach and the need for anticoagulation to cover the risk of thromboembolism.

Bordachar P et al (J Am Coll Cardiol, 2010; 56:747-753) et al reviewed the current data on left ventricular (LV) endocardial stimulation for heart failure. They suggest that the implementation of LV endocardial pacing will depend on development of safe, effective and durable devices which could provide reliable pacing and methods to identify optimal sites for pacing. Long term controlled trials should document the benefits and superiority of LV endocardial pacing before it can be put to clinical practice.

A study by Spragg DD et al (J Am Coll Cardiol, 2010; 56:774-781) tried to identify optimal sites for LV endocardial pacing in ischemic cardiomyopathy. They could document that LV endocardial BiV (biventricular) pacing improved the dP/dt_max over right ventricular apical pacing in all patients. In those with pre-existing coronary venous leads, pacing at transmural sites gave similar values of dP/dt_max. Optimal endocardial sites of LV pacing were located at the extreme basal lateral wall and provided better dP/dt_max than the pre-existing CRT leads. These optimal pacing sites were remote from the sites of myocardial scars at an average distance of about 9 cm.