LV pacing

Device: CRT Field: Left ventricle pacing

1. Basic concepts

LEFT VENTRICULAR PACING

Four different approaches have been proposed to allow for left ventricular stimulation: epicardial stimulation with a trans-venous lead positioned in a branch of the coronary sinus, endocardial stimulation with a trans-septal lead, direct epicardial stimulation after surgical placement of the lead on the left ventricule, and finally the epicardial stimulation via a lead placed directly by percutaneaous puncture in the pericardial space. The trans-venous approach represents the reference method and the first-line approach in a majority of centers. The coronary sinus drains almost the entire left ventricle and also the atria. The length, orientation and diameter of the coronary sinus are highly variable and makes difficult to predict the feasibility of the procedure. Several valves can obtrude or reduce the caliber of the coronary sinus. The Thébésius valve is found just at the ostium, the valve of Vieussens at the ostium of the first postero-lateral vein. The phrenic nerve is located along the lateral veins, along a posterior side branches of the anterior vein and finally along the anterior veins emerging from the postero-lateral vein.

Schematically, the implantation procedure follows the next steps: venous access, introduction of a support sheath in the right atrium, cannulation of the coronary sinus, contrast media injection and selection of the target vein, positioning of the lead, sheath removal.

Recent years have been marked by the development of new leads of variable sizes and shapes. Once the contrast injection is completed, the operator can choose the best lead corresponding to the anatomical characteristics of the target vein. The size of the ostium of the target vein and the caliber of its main part are crucial for this choice. The operator must find a good match between lead diameter and size of the internal lumen of the vessel. Some other parameters that are difficult to predict will also influence the choice of the stimulation site and therefore the choice of the optimal lead: the presence of high thresholds and the presence of phrenic nerve stimulation.

PACING CONFIGURATION

For more informations, refer to chapters specificities by manufacturers.

2. Specificities by company