Optimal Atrioventricular Intervals During Dual Chamber Pacing in Patients with a Univentricular Heart: A Doppler Hemodynamic Evaluation JOERG NOTHROFF, REINER BUCHHORN, and WOLFGANG RUSCHEWSKI* From the Departments of Pediatric Cardiology and *Thoracic and Cardiovascular Surgery, University Hospital, Georg-August-Universit¨ at G ¨ ottingen, Germany NOTHROFF, J., ET AL.: Optimal Atrioventricular Intervals During Dual Chamber Pacing in Patients with an Univentricular Heart: A Doppler Hemodynamic Evaluation. The benefit of a dual chamber pacemaker and the atrial and ventricular synchronization in patients with two ventricles is widely accepted. The purpose of this study was to choose the optimal AV interval in patients with congenital heart disease after definitive palliation of univentricular hearts. Therefore, different AV intervals were programmed and hemodynamic aspects were examined by Doppler echocardiography. The interval found was different from normal heart morphology and two ventricular hemodynamics. (PACE 2003; 26:2048–2049) univentricular heart, dual chamber pacing, optimal AV delay Introduction Synchronization of atrial and ventricular acti- vation has an impact on hemodynamic and clini- cal benefits in patients with a dual chamber pace- maker. In general, pacing therapy involves the right ventricle and the right atrium. The impor- tance of programming an optimal atrioventricular (AV) interval in DDD pacing has been widely ac- cepted. 1 According to the cardiac cycle, 2 we can determine the closure of the AV valves by pro- gramming the optimal AV interval to achieve the electromechanical synchronization of atrium and ventricle. Therefore, we can realize the longest possible diastolic filling time for maximal cardiac output. When programmed incorrectly the advan- tage to cardiac output of a patient with a dual chamber pacemaker can nearly decrease to the level of ventricular pacing. 3 There are few data for patients with dual chamber pacemakers and con- genital heart disease with complex cardiac mor- phology. 4 Patients with univentricular hearts have to undergo surgery for separation of the systemic and pulmonary circulation system according to the method first described by Fontan. The most pop- ular method is the surgery with an extracardiac conduit to prevent atrial arhythmias. Suboptimal flow dynamics, arrhythmias, and thromboembolic complications alter the quality-of-life of these pa- tients. Therefore, the importance of sinus rhythm could be easily understood. The aim of this study was to achieve the maximum cardiac output for Address for reprints: Joerg Nothroff, M.D., Dept. Pediatric Cardiology, Georg-August-University Goettingen, Robert- Koch-Str. 40, D-37075 Goettingen, Germany. Fax: 0049551/ 392560; e-mail: joerg.nothroff@med.uni-goettingen.de or jsnothroff@web.de Received June 4, 2002; revised November 18, 2002; accepted February 5, 2003. patients with definitive palliation of an univentric- ular heart and dual chamber pacemaker and com- pare it with recommendations for “normal heart morphology.” Methods Two male patients (age 9 and 38 years) with palliation of an univentricular heart and total cavopulmonary connection (TCPC) with an ex- tracardial conduit underwent dual chamber pace- maker implantation (Marathon and Relay DDD-R pacemaker from Intermedics, Inc., Angleton, TX, USA) with unipolar epimyocardial leads (Osypka GmbH, Grenzach-Whylen, Germany) because of third-degree AV block. During routine pacemaker control they were examined with pulsed-wave Doppler echocardiography and recording of sur- face electrocardiograph (ECG). Both patients were in sinus rhythm and had no signs of conges- tive heart failure or AV valve insufficiency. The Doppler echocardiographic examination was per- formed in “mitral flow” with a Sonos 1000 ul- trasound system (Hewlett-Packard Inc., Andover, MA, USA) using a 3.5-MHZ or 2.5-MHZ trans- ducer. Measurement of cardiac output or blood flow can be calculated by multiplying the mean velocity of flow and the cross-sectional area of the valve as shown in the following equation: Cardiac output (L/min) = VTI × HF × V sa , where VTI is the measured velocity time integral obtained from the computer program of the ultrasound system. V sa is the cross-sectional area of flow measured or com- puted from the two dimensional echo and HF is representing the heart rate during measurement. If V sa and HF are constant, then cardiac output is pro- portional to VTI. Because there is no change of the AV valve area and the heart rate during examina- tion, cardiac output (CO) can be set proportional to VTI: CO ∼ VTI. Mean VTI was calculated by averaging three consecutive measurements. Both 2048 October 2003 PACE, Vol. 26