Pacemaker syndrome evaluated by cardiopulmonary exercise testing.
Two patients who presented with dyspnea on effort, persisting after insertion of a fixed rate ventricular demand pacemaker (VVI) for sick sinus syndrome, were evaluated by cardiopulmonary exercise testing. During VVI pacing a heightened ventilatory response to exercise and a fluctuation of ventilation occurred. The high ventilatory equivalent for CO2 throughout exercise with VVI pacing suggests that the patients had ventilation-perfusion mismatching due to an increase in the pulmonary capillary wedge pressure caused by 1:1 ventriculoatrial conduction. Rate responsive ventricular (VVIR) pacing associated with intact 1:1 ventriculoatrial conduction exaggerated the exertional dyspnea, while rate responsive atrial (AAIR) pacing improved the ventilatory response to exercise. We suggest that a heightened ventilatory response to exercise due to ventilation-perfusion mismatching may be an important factor causing the pacemaker syndrome, and that cardiopulmonary exercise testing is useful in identifying the exercise-induced symptoms with ventricular pacing.
Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Japan.
A
A
Fujiki
M
M
Tani
K
K
Mizumaki
H
H
Asanoi
S
S
Sasayama
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D004417:Dyspnea / Q000209:etiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D007022:Hypotension / Q000209:etiology; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011659:Pulmonary Gas Exchange / Q000502:physiology; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D013575:Syncope / Q000209:etiology; D013577:Syndrome