Cardiac resynchronization (CRT ) as a modality for severe or refractory cardiac failure patients with wide QRS complex, is practiced for nearly two decades. It works on the principle of aggregating mechanically wasted and disorganized myocardial contractile force into a coherent forward pushing activity. This is done by stimulating the heart at strategic points by inserting wires. In the process, CRT improves the ejection fraction and possibly reduce mitral regurgitation.
Still, the optimal benefit of CRT concept has been difficult to extract from this device. The primary reason is, the LV epicardial lead pacing site was pre-selected by the coronary sinus anatomy. This has made the whole concept of RV-LV synchronization a futile exercise in many. No surprise, non, poor responders or even adverse responders were as high as true responders.
What is new in CRT ?
While one group of electrical scientists is trying hard to create evidence that conduction system pacing (CSP) is equivalent to CRT, that is devoid of procedural complexity of CRT. We now have one more technology, on the verge of approval by the FDA . This uses tiny leadless endocardial electrodes in well-selected sites within the chamber of LV .
free from scars. This can be done with aid of with intracardiac echo imaging. This electrode is stimulated by self-generated electricity from an external ultrasonic waves transmitted from the surface of the heart.
This weeks JAMA has reported an encouraging results with this device .The study documented reduction in end systolic volume by 16% and the ejection fraction as well. (Red 1)
What about totally leadless CRT ?
Yes it’s in the offing. Micra device which is lead less RV pacing system is being combined with WiSE CRT, making a totally leadless CRT a possibility. .
A patient chest X-ray showing both Micra and WiSE-CRT systems. Green: Micra leadless pacemaker; blue: WiSE-CRT system LV endocardial electrode; and red: WiSE-CRT system subcutaneous battery and ultrasound generator. CRT, cardiac resynchronization therapy. (Carabelli A, Jabeur M, Jacon P, Rinaldi CA, European experience with a first totally leadless cardiac resynchronization therapy pacemaker system. Europace. 2021 May 21;23(5):740-747. )
Final message
WiSE CRT uses some revolutionary technology and it is a welcome addition in few eligible patients. However, advanced heart failure therapy never means it can be achieved only by state-of-the-art technology. Cardiac failure management remains basically disciplined medical management and a holistic approach to improve the quality of life. Only few lucky patients end up getting heart transplantation, the ultimate treatment.
One of my patients said he reduced his weight corresponding to his reduction in ejection fraction and he now walks double the distance than before. The answer is that simple; you can use a 100k device and try to walk 30 meters extra or use the free option.
Reference
Dr.S.Venkatesan MD 