Transvenous biventricular defibrillation halves energy requirements in patients

Background-Defibrillation thresholds (DFT) with standard implantable cardio verter-defibrillator leads in the right ventricle (RV) may be determined by weak shock field intensity in the myocardium of the left ventricle (LV). A dding a shocking electrode in a coronary vein on the middle of the LV free wall, thereby establishing biventricular defibrillation, substantially redu ced defibrillation requirements in animals. We investigated the feasibility of this approach in 24 patients receiving an implantable cardioverter-defi brillator using a prototype over-the-wire temporary LV defibrillation lead. Methods and Results-The LV lead was inserted through the coronary sinus, us ing a guide catheter and guidewire, into a posterior or lateral coronary ve in whose location was determined by retrograde venography. Paired DFT testi ng compared a standard system (RV to superior vena cava plus can emulator [ SVC+Can], 60% tilt biphasic shock) to a system including the LV lead. The b iventricular system was tested with a dual-shock waveform (20% tilt monopha sic shock from LV --> SVC+Can, then 60% tilt biphasic shock from RV --> SVC +Can). Twenty patients completed DFT testing. Venography and LV lead insert ion time was 46 +/- 40 minutes. The biventricular system reduced mean DFT b y 45% (8.9 +/-1.1 J versus 4.9 +/-0.5 J, P <0.001). Twelve patients (60%) h ad a standard system DFT :S J, and the biventricular system gave a lower DF T in all patients. There were no adverse events related to the use of the L V lead, which was removed after testing. Conclusions-Internal defibrillation using a transvenously inserted LV lead is feasible, produces significantly lower DFTs, and seems safe under the co nditions tested. Biventricular defibrillation may be a useful option for re ducing DFTs or could be added to an LV pacing lead for heart failure.