Comparison of DDD and 'VVI-R like' pacing during moderate exercise: echo-Doppler study

Area of Science:

• Cardiology
• Biomedical Engineering
• Physiology

Background:

• Dual chamber pacing (DDD) and ventricular pacing (VVI-R) are common modes for cardiac rhythm management.
• Understanding their hemodynamic effects during exercise is crucial for optimizing patient care.

Purpose of the Study:

• To compare the non-invasive hemodynamic effects of DDD and VVI-R pacing modes at rest and during moderate exercise using echocardiography Doppler.

Main Methods:

• Twelve patients with dual chamber pacemakers underwent two exercise tests: one in DDD mode and another in a VVI-R like (VVT) mode.
• Ventricular pacing rate was matched to the DDD mode's heart rate profile during the VVI-R test via external chest wall stimulation.
• Echocardiography Doppler was used to record and analyze aortic blood flow velocity spectra, calculating parameters like stroke volume and cardiac output.

Main Results:

• At rest, several hemodynamic parameters differed between DDD and VVI-R modes, including ejection time, flow velocity integral, flow acceleration, and stroke volume.
• During exercise, most parameters differed, with DDD mode showing significantly larger stroke volume (81.9 vs 70.9 ml) and cardiac output (9.24 vs 8.01 L/min) compared to VVI-R mode (P < 0.001 for both).

Conclusions:

• DDD pacing demonstrates superior hemodynamic efficiency over VVI-R pacing during moderate exercise in patients with dual chamber pacemakers.
• The findings suggest that DDD pacing better supports circulatory function during physical activity compared to VVI-R pacing.