The target
coronary vein should be carefully selected for optimal left ventricular stimulation during CRT (4).
All of this forces arterial blood to pass into the
coronary vein, creating an in-situ bypass.
The reasons for difficult LV lead implantations are coronary venous system related issues (failure to access coronary venous system and anatomic variations in the
coronary veins), extensive scar tissue in the target region for LV pacing, phrenic nerve stimulation, and LV lead instability.
Another issue that can happen is that the other
coronary veins and arteries are not properly formed, so this can lead to a decrease of blood, or blood going to the wrong areas of the body.
The main limitations of percutaneous techniques for MVR using the transcoronary venous approach are the variability in coronary venous anatomy, the presence of venous valves within the
coronary veins, and the variability of the crossing point of the great cardiac vein and circumflex artery.
Coronary veins: These veins shuttle blood and harmful waste products away from the heart.