Optimal AV delay in ventricularly paced adults with congenital heart disease

The atrioventricular (AV) delay may be altered in ventricularly paced patients with either dual-chamber pacemakers or cardiac resynchronization therapy (CRT), to optimize diastolic filling and cardiac output, but such modifications are virtually unstudied in the setting of complex congenital heart disease (CHD). We sought to assess the optimal AV delay in a pilot study of ventricularly paced adults with CHD. AV delay optimization was performed by the iterative method utilising pulsed wave Doppler of systemic AV valve inflow, in the patient's presenting rhythm (atrial-sensed or paced). Diastolic filling time (DFT), inflow and outflow velocity time integrals (VTI) were compared at optimal and nominal AV delay settings. Nine patients were studied with the following CHD diagnoses: congenitally corrected transposition of the great arteries (TGA) in 4, D-TGA post Senning in 2, tetralogy of Fallot in 2 and Fontan circulation in 1. The median optimal AV delay was 100 ± 20 ms, shorter than the median nominal AV delay of 150 ± 20 ms. The median difference between optimal and nominal AV delay setting was 50 ± 40 ms, with the optimal AV delay shorter than the nominal in all but one patient. At optimal AV delay, the DFT was longer, and inflow and outflow VTIs were larger, compared to nominal. AV delay optimization in ventricularly paced adult CHD patients resulted in an optimal AV delay that differed to the nominal setting in all patients, and typically was shorter.