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Eur J Cardiothorac Surg 1998;14:419-425
© 1998 Elsevier Science NL

Effect of implantable cardioverter/defibrillator lead placement in the right ventricle on defibrillation energy requirements. A combined experimental and clinical study¹

^a Department of Thoracic and Cardiovascular Surgery, Heinrich-Heine-University, Duesseldorf, Germany
^b Tachyarrhythmia Therapy Research, CPI Guidant, St. Paul, MN, USA
^c Department of Cardiology, Heinrich-Heine-University, Duesseldorf, Germany
^d Department of Experimental Surgery, Heinrich-Heine-University, Duesseldorf, Germany

Received 1 December 1997; received in revised form 19 July 1998; accepted 28 July 1998.

Corresponding author. Department of Thoracic and Cardiovascular Surgery, University of Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany. Tel.: +49 211 81 18331/17376/17355; fax: +49 211 81 18280.

Objectives: The effect of implantable cardioverter/defibrillator (ICD) lead placement in the right ventricle (RV) on defibrillation efficacy has not been thoroughly investigated. Therefore, the goal of this combined experimental and clinical study was to evaluate the effect of a septal and a non-septal position of the right ventricular endocardial spring lead on defibrillation energy. Methods: In 12 isoflurane-anaesthetized swine and subsequently in 8 patients who underwent ICD implantation, two different positions of the distal spring lead in the RV were investigated in randomized order: non-septal position (free wall of the RV) and septal position (interventricular septum). For each position, separate 50% probability determinations of energy (E₅₀), peak voltage (V₅₀) and peak current (A₅₀) were calculated using the three reversal up/down defibrillation procedure. The E₅₀, V₅₀, A₅₀ and impedance (I) were averaged and compared using the two-sided t-test for paired samples. Results: Both the experimental study and the clinical study demonstrated that placing the distal defibrillation lead near to the septum rather than near to the ventricular free wall resulted both in the swine and in the patients in significantly lower E₅₀ -31.6%/-37.1%, V₅₀ -16.1%/-20.9% and A₅₀ -10.0%/-24.2%, respectively. Defibrillation impedances were significantly reduced only in the experimental study. Conclusions: Defibrillation efficacy depends on the position of the distal spring electrode in the RV. A septal position significantly reduces the energy requirements compared to a non-septal position. The decrease in energy requirements might be explained by an increase in current flow through the septum and the posterolateral wall of the left ventricle.

Key Words: Implantable cardioverter/defibrillator • Endocardial lead placement • Defibrillation energy requirements • Electrode positions