TRANSESOPHAGEAL ECHOCARDIOGRAPHIC EVALUATION OF VENTRICULAR-FUNCTION DURING TRANSVENOUS DEFIBRILLATOR IMPLANTATION

Background: Intraoperative testing and defibrillation threshold determ ination may jeopardise patients, scheduled for implantation of a cardi overter-defibrillator (ICD). The purpose of this study was the assessm ent of the influence of consecutive defibrillation attempts on left ve ntricular systolic and diastolic function by means of transoesophageal echocardiography (TEE). Methods: Eighteen patients with malignant ven tricular arrhythmias that were resistant to antiarrhythmic drugs were monitored with TEE before, during and after implantation of a cardiove rter-defibrillator. Left ventricular fractional area contraction as a measure of ejection fraction was assessed before and after each defibr illation attempt. Transmitral and right upper pulmonary venous flow pa rameters were evaluated before and after the whole implantation proced ure. Results: Adequate data were available in 14 patients during 4 con secutive attempts. No major alterations were observed in heart rate or fractional area contraction, measured at 30 s and 3 min after defibri llation. Overall, the ratio of early-to-late transmitral filling decre ased significantly after the implantation procedure (from 0.91+/-0.12 to 0.82+/-0.14; P<0.05). Systolic pulmonary venous flow velocity decre ased from 0.49+/-0.11 to 0.41+/-0.10 m/s (P=0.04); this decrease was o bserved in both groups. A significant increase of the atrial contracti on wave (from 0.25+/-0.06 to 0.34+/-0.07 m/s; P<0.03) was seen. Subdiv iding patients related to their preoperative ejection fraction, a sign ificant decrease of the early-to-late transmitral filling of the LV wa s revealed in patients with ejection fraction less than 35% (group 1). Also, a significantly lower systolic fraction of the pulmonary venous flow after ICD implantation in conjunction with a significantly longe r diastolic flow time was shown in this patient group in comparison wi th patients with a preoperative ejection fraction of more than 35% (gr oup 2). Conclusion: Defibrillation threshold testing of the ICD system changes LV inflow characteristics and impedes diastolic function of t he left ventricle and may thus precipitate heart failure by this mecha nism. No deleterious effects of threshold testing were observed with r espect to fractional area contraction nor any deterioration of LV func tion was found in a clinically significant amount due to consecutive d efibrillation attempts.