Cardiac resynchronization therapy

Intra- or interventricular dyssynchrony associated with delayed intra- or interventricular conduction is an essential component of pathogenesis of severe chronic heart failure.

In HF, intra- and interventricular interactions are altered. Normal physiological asynchronism between interventricular septum (IVS) and posterior wall of LV (about 60 msec) increases and leads to LV dysfunction.

Cardiac resynchronization allows to change a degree of electromechanical asynchrony of atria and ventricles. The indicator for prediction of cardiac resynchronization success is the initial prolongation of QRS interval >130 msec. The most informative criterion is the assessment of intraventricular mechanical delay of contraction — the increase in initial intra- or interventricular mechanical asynchrony >50 msec.

Surgical technique

Such disorders are corrected by implantation of a multichamber pacemaker with separate stimulation of the right atrium and ventricles. For this purpose, three electrodes are inserted through a subclavian vein and fixed to a wall of the right atrium, in an apex of RV and through a coronary sinus in the left lateral vein of LV at the heart basis.

In open myocardial revascularization surgeries, LV remodeling or mitral valve plasty, electrodes are fixed epicardially — in the right atrium and at the base of the heart to both ventricles.

The mandatory condition of resynchronization efficiency is the optimization of pacemaker operation.