Advantages of dual chamber rate adaptive pacing compared with ventricular rate adaptive pacing in patients with pulmonary disease

The relative benefits of dual chamber adaptive rate pacing (DDDR) were compared with ventricular adaptive rate pacing (VVIR) in patients with chronic obstructive pulmonary disease (COPD) who required pacing. Patients with normal lung function (NLF) served as a control group. Eleven patients were studied with a multistage treadmill exercise protocol in the DDDR and VVIR modes. All patients had symptomatic bradycardia, five patients had COPD, and six patients had NLF. Pulmonary gas exchange data was measured at rest and during exercise. Echo-Doppler cardiac output determinations were made at rest and immediately after exercise. Rest and exercise performance data in each mode were compared for the COPD and NLF populations. Both groups showed consistently better performance with DDDR. Cardiac output (CO) showed the greatest improvement, with an average adjusted CO at peak exercise of 8.09 L/min DDDR vs 5.73 L/min VVIR in the COPD group and 11.92 L/min DDDR vs 6.69 L/min VVIR for the NLF group. Although the relative degree of improvement differed between the two groups, both showed improved cardiac performance in DDDR mode at rest and during exercise. A delay in the onset of the anaerobic threshold (AT), combined with an increase of 15% in exercise duration in the COPD population, suggested that DDDR would aid in rehabilitation and improve quality of life in patients with COPD who require cardiac pacing.