RÉSUMÉ
Dual chamber pacing has become the most common pacing mode because it is capable of sensing and pacing in both the atrium and ventricle and can track atrial activity. It is least competitive with intrinsic rhythm and it maintains AV sequencing as well as rate adaptation by tracking the normally functioning atria. However the presence of atrial lead has been found to bring on some problems. The aim of this work was to study the role of exercise test as a diagnostic tool in atrial lead malfunction in dual chamber pacemakers and to study the effect of physical exercise on P wave amplitude. This study included thirty Patients, 28 with DDD pacemakers and 2 with VDD pacemakers who were referred for pacemaker follow up at Ain shams university hospital. For inclusion in the study patients should have maintained intrinsic atrial activity and should have an apparently well functioning pacemaker by surface ECG. Patients with sever heart failure, ischemic heart disease and those who were totally dependant on atrial pacing were excluded. After history taking and physical examination, pacemakers were interrogated by the appropriate programmer for measurement of sensing and pacing functions of atrial and ventricular leads in both unipolar and bipolar configurations before and after doing an exercise test according to Bruce protocol. The atrial leads implanted in the studied group were J-shaped screw-in steroid eluting leads in 18 patients, straight screw-in steroid eluting leads in 5 patients, and straight screw-in non steroid eluting leads in 5 patients. Two patients received single lead VDD pace makers. 10 patients had complaints while 20 patients did not have any complaint. Atrial lead malfunction was detected by exercise test in 5 patients, all of them were complaining. Two of these 5 patients [one with VDD and one with DD pacemaker] had true undersensing, two had functional undersensing and one had over sensing. There was no difference in P wave amplitude before and after exercise.:Exercise stress test is a helpful tool in detecting atrial lead malfunction in patients with DDD/VDD pacemakers who have a normal ECG with normal supine atrial lead function and are complaining of dizziness and/or fatigue. lt has a positive predictive value of 100% and a negative predictive value of 80%.In the presence of complaints, [dizziness and/or fatigue], it is a highly specific test to exclude abnormal pacemaker function