A high dose of adenosine to induce transient asystole for valvuloplasty in patients undergoing transcatheter aortic valve implantation (TAVI): Is it a valid alternative to rapid pacing a prospective pilot study

BACKGROUND: Rapid right ventricular pacing (RRVP) at rates above 200 beats/minute is used to suppress cardiac output during balloon aortic valvuloplasty (BAV) in transcatheter aortic valve replacement (TAVI) patients. A risk of inducing myocardial ischemia with RRVP remains, especially in patients with left ventricular dysfunction. Alternatively, a transient cardiac arrest can be achieved with administration of adenosine. METHODS: The primary endpoint was successful valvuloplasty defined by complete balloon inflation and deflation across aortic valve during the transient asystole induced by adenosine. Secondary endpoints were defined as the failure of adenosine to induce asystole, the incidence of ventricular ectopic beats (VEB) during balloon inflation or deflation, and balloon displacement. RESULTS: From November 2010 to January 2011, twenty consecutive patients who underwent TAVI were included. A balloon for valvuloplasty was positioned across the aortic valve. A low-dose (24 mg, n ≤ 10) or high-dose (36 mg, n ≤ 10) bolus of adenosine was administrated. A single bolus of adenosine-induced atrioventricular (AV) block (mean duration, 18.6 ± 6.6 seconds) followed by cardiac asystole in 16 patients (80%) (low-dose, n ≤ 9). A successful BAV was achieved in 12 patients (60%) (low-dose, n ≤ 8). Adenosine induced only bradycardia in 4 patients (20%) (low-dose, n ≤ 1). A burst of VEB during BAV occurred in all patients. Balloon displacement occurred in 6 patients (37.5%). CONCLUSION: BAV after administration of adenosine is feasible, safe, and may represent an option for high-risk TAVI patients in whom RRVP might not be well tolerated. The occurrence of ventricular ectopic contractions triggered by balloon inflation and deflations accounts for balloon displacement and crossover to RRVP.