Heart failure is a life-threatening cardiac disease, which occurs when the heart is no longer able to pump enough blood to meet the needs of the body. Treatments for heart failure depend on the stage and severity of the disease.
Cardiac resynchronization therapy (CRT) is one of the treatments for heart failure and is indicated for patients with desynchronization of the two ventricles.This desynchronization affects around 10% of the total heart failure population. It is estimated that around 400 patients per million population per year could be indicated for CRT1. The goal of CRT is to resynchronize the beating of the heart by pacing at the same time both the right ventricle (RV) and left ventricle (LV). This therapy is delivered by a pulse generator connected to three leads equipped with a set of distal electrodes designed to electrically stimulate and sense the heart. The leads are placed in the right atrium, right ventricle and left ventricle.
It is now well established that CRT improves patient quality of life, decreases hospitalization for acute heart failure and most importantly decreases overall mortality2. However, benefits at the individual level vary considerably. Depending on the definition, the response to CRT is positive in only around 50-80% of patients, leaving 20-50% without any significant effect3.
In particular, optimizing the position of the LV lead can significantly increase the rate of responders to CRT (83% vs. 65%, as described in the TARGET study4). As opposed to RA and RV leads, LV lead positioning is a particularly difficult and long procedure, as it is placed in the coronary venous system coursing along the left ventricle, through narrow and tortuous veins, whose anatomy can vary significantly from one patient to another.
With its ultra-thin lead design (0.3 mm diameter), Axone can be introduced into very narrow veins, which are not accessible with current LV leads on the market. Therefore, Axone provides more options for LV pacing sites and could facilitate LV lead placement procedures by enabling physicians to reach any target vein.
Axone is a quadripolar lead equipped with a standard IS4 connector, with independently programmable sets of electrodes. There are 4 models in the Axone 4LV range, which provide a choice of inter-electrode distance ranging from 50 mm to 250 mm. This allows for multi-zone pacing of the left ventricle and subsequently potential improved resynchronization due to the enlarged pacing area.
The Axone 4LV lead is currently subject to a clinical evaluation and is not commercially available.
REFERENCES
[1] Brignole M et al. 2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: the Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Eur Heart J 2013;34:2281–2329.[2] Cleland JG, Daubert JC, Erdmann E, et al. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med 2005;352:1539-49.[3] Daubert JC et al. 2012 EHRA/HRS expert consensus statement on cardiac resynchronization therapy in heart failure. Europace. 2012;14:1236-1286.[4] Khan FZ, Virdee MS, Palmer CR, et al. Targeted left ventricular lead placement to guide cardiac resynchronization therapy: the TARGET study: a randomized, controlled trial. J Am Coll Cardiol 2012;59:1509-1518.