Biventricular Pacing With Ventricular Fusion by Intrinsic Activation in Cardiac Resynchronization Therapy

Abstract

SummaryWe sought to evaluate the impact of biventricular (BiV) pacing with ventricular fusion by intrinsic atrioventricular nodal (AVN) conduction (BiV + intrinsic pacing) on clinical outcomes in patients with chronic heart failure (CHF) receiving cardiac resynchronization therapy (CRT).A total of 44 patients were randomized to receive either BiV or BiV + intrinsic pacing for one month. Echocardiographic optimization was performed for the BiV pacing mode, while the BiV + intrinsic pacing mode was achieved by titrating AV delay under electrocardiography (ECG) monitoring. Symptoms, quality of life, ECG, echocardiography, and cardiovascular events were recorded at baseline and the end of the follow-up for each pacing mode.Patients undergoing BiV + intrinsic pacing mode had shorter QRS duration compared to those with conventional BiV pacing (118.4 ± 21.6 ms versus 146.4 ± 5.3 ms, P < 0.0001). Also, these patients had improved echocardiographic left ventricular fractional shortening (LVFS) (17.4 ± 5.9 versus 15.7 ± 4.9, P = 0.019), higher left ventricular ejection fraction (LVEF) (35.5 ± 9.7 versus 32.7 ± 9.7, P = 0.048), longer 6-minute walk test (6MWT) (372.5 ± 80.9 m versus 328.7 ± 108.9 m, P = 0.0001), and better Minnesota Living with Heart Failure Questionnaire (MLHFQ) scores (12.5 ± 6.6 versus 18.2 ± 12.3, P = 0.0001).Treating CHF patients with BiV+intrinsic pacing resulted in improved cardiac function and quality of life. BiV + intrinsic pacing can be used in CHF patients with sinus rhythm and normal AV nodal conduction to improve CRT efficacy. (Int Heart J 2015; 56: 293-297) Key words: Intrinsic conduction, Heart failure, Electrocardiography, Echocardiography C ongestive heart failure (CHF) is a major public health problem associated with high mortality and morbidity. 1) Common causes of CHF include, but are not limited to ischemic heart disease, hypertension, arrhythmias, valvular diseases, cardiomyopathies, and congenital heart diseases.2,3) Cardiac resynchronization therapy (CRT), also known as biventricular pacing (BiV) or multisite ventricular pacing, simultaneously paces the right ventricle and the left ventricle. Large randomized clinical trials have shown that CRT improves symptoms, cardiac functions, and survival in patients with heart failure who have electrical dyssynchrony. CRT has been recommended by the American Heart Association (AHA) guidelines for patients with recurrent symptoms of systolic heart failure and a wide QRS complex, despite being on optimal medical therapy. [4][5][6][7][8] CRT allows for more efficient blood ejection by reducing mechanical inefficiency from dyssynchronous contraction. 3,9,10) However, there is a wide spectrum of clinical responses to CRT and one third of the patients who are selected for CRT fail to demonstrate any benefit from it.11,12) Therefore, the current clinical focus in CRT is to maximize the benefit from this therapy.A physiological approach to pacing is important for patients with CHF. It can be achieved by a number of methods including CRT, rate ada...

The concept of triple wavefront fusion during biventricular pacing: Using the EGM to produce the best acute hemodynamic improvement in CRT

“…They found that optimal ventricular resynchronization was reached when BiVp fused with intrinsic conduction. These findings confirm similar observations in other studies …”

“…The majority were men (N = 10 [65%]). Mean LVEF was 20 ± 7%, 53% had an ischemic cardiomyopathy and 82% had an LBBB following the definition of Strauss . Mean PQ was 180 ± 24 ms and mean QRS duration 173 ± 28 ms. Absolute LV dP/dt max during intrinsic conduction was 709 ± 169 mm Hg/s (Table ).…”

“…Furthermore, it has been suggested that optimized BiVp also involves intrinsic conduction contributing to ventricular depolarization next to both right ventricular and left ventricular pacing (resp. RVp and LVp) wavefronts, in other words triple wavefront fusion …”

“…However, no such EGM method is available using the concept of aiming at triple wavefront fusion. Studies showing triple wavefront fusion during optimal BiVp have used electroanatomic mapping and surface electrocardiogram (ECG) to assess the presence of BiVp with fusion (BiVp‐fusion, respectively, triple wavefront fusion) . Although these are sophisticated methods to assess the contribution of three wavefronts to resynchronization, an EGM‐based method is mandatory to provide an easy automatic assessment.…”

A Simple Method to Differentiate Atrioventricular Node Reentrant Tachycardia from Orthodromic Reciprocating Tachycardia

“…[8][9][10] Electrical stimulation is widely used in electrophysiology. [11][12][13] His bundle refractory period pacing is used to differentiate AVNRT from ORT. Although the change of the atrium activity when ventricular pacing during the His bundle refractory period is useful, it seems that not all ventricular pacing in the His bundle refractory period could conduct to the atrium.…”