P189 WHEN A PACEMAKER CAN BE HARMFUL IN A PATIENT WITH COMPLETE AV BLOCK

Abstract

Abstract The occurrence of complete AV block in patients with aortic valve stenosis is a frequent event and the implantation of a dual–chamber pacemaker is the therapy of choice for these cases. We present the case of an 84–year–old hypertensive diabetic patient hospitalized with heart failure during a severe anemia caused by bleeding duodenal ulcer (Hb < 7g/dl). The patient was treated with blood transfusions, proton pump inhibitors, and endoscopic ulcer treatment with clinical stabilization. However, he presented a third–degree AV block, with a narrow QRS escape rhythm of about 45 bpm. The echocardiogram showed a calcified aortic valve with severe stenosis (transvalvular flow 4m/s, valvular area 0.9 cm2) ( fig1–2), with moderate mitral regurgitation and preserved systolic function (EF 60%). He was therefore subjected to a dual–chamber pacemaker implant. In the hours following the procedure, with heart rate increased to 90 bpm and correct AV synchronism, the patient presented an episode of acute pulmonary edema, treated with diuretics, oxygen and nitrogliceryn. with initial clinical improvement but subsequent new instabilization. The echocardiogram showed worsening of systolic function with septal dyssynergia secondary to electrostimulation and a severe mitral regurgitation (fig 3). The clinical status definitively stabilized only after changing the pacemaker programming to VVI 40 bpm (sentinel mode). The patient repeatedly refused the indications for aortic valve replacement surgery, and was therefore discharged with medical supportive care, third–degree AV block at electrocardiogram and a dual–chamber pacemaker programmed in sentinel VVI to obtain a minimal ventricular pacing. After 24–month follow–up, the patient remains in good clinical conditions, he was never hospitalized again, the third–degree AV block persists with PM stimulation percentages of 5%. This clinical case shows how electrostimulation and increased heart rate, in the presence of aortic outflow obstruction and significant mitral valve disease, can cause very insidious acute left ventricular systolic dysfunction, while restoring correct AV synchrony.