Up and Down in Device Therapy

History

The patient underwent bypass surgery (left internal mammary artery to left anterior descending artery and saphenous vein graft to distal right coronary artery) 13 years previously. Three months later, routine Holter electrocardiogram (ECG) monitoring revealed asymptomatic episodes of second-degree and third-degree atrioventricular block. The patient refused pacemaker implantation because of lack of symptoms.

In December 2002 the patient developed dyspnea (New York Heart Association [NYHA] class II). Another 24-hour ECG showed not only high-degree atrioventricular block but also sinus bradycardia. A dual-chamber pacemaker was implanted in February 2003. Follow-up was uneventful, and right ventricular pacing was reported to be almost 100%.

In December 2005 angiography was performed for atypical chest pain and a slight increase in dyspnea. No significant stenosis was present, but his left ventricular ejection fraction (LVEF) had decreased to 25%. Therefore an upgrade to a cardiac resynchronization therapy defibrillator (CRT-D) was carried out in February 2006.

In May 2007 the patient was free from dyspnea and echocardiography showed a normal LVEF of 73%.

The patient remained asymptomatic, and no arrhythmias, apart from paroxysmal atrial fibrillation, were recorded in the implantable cardioverter-defibrillator (ICD) memory. In July 2011 the battery was depleted (elective replacement indicator). Another echocardiogram confirmed a preserved LVEF of 60%. The patient was in NYHA class I. During VVI pacing with 30 bpm, no intrinsic ventricular activity is present.

Current Medications

The medications the patient was taking in February 2003 were atorvastatin 10 mg daily and aspirin. In February 2006 he was taking ramipril 7.5 mg daily, metoprolol 50 mg twice daily, torsemide 10 mg daily, atorvastatin 20 mg daily, and aspirin. In July 2011 he was taking ramipril 7.5 mg daily, metoprolol 50 mg twice daily, torsemide 10 mg daily, simvastatin 80 mg daily, and warfarin.

Current Symptoms

The patient had no angina, dyspnea, or peripheral edema.

Physical Examination

• BP/HR: 115 over 75/72

• Height/weight: 181 cm/108 kg, body mass index 33

• Neck veins: Normal

• Lungs/chest: N ormal

• Heart: Normal heart sounds

• Abdomen: Normal

• Extremities: No peripheral edema

Laboratory Data

• Hemoglobin: 115/75 mg Hg

• Hematocrit/packed cell volume: 47%

• Mean corpuscular volume: 93 fL

• Platelet count: 219 × 10 ³ /µL

• Sodium: 143

• Potassium: 4.1

• Creatinine: 98 μmol/L

• Blood urea nitrogen: 8 mmol/L

Electrocardiogram

Findings

The electrocardiogram revealed atrioventricular sequential pacing, paced QRS complex at 168 ms, and positive findings in lead V ₁ ( Figure 30-1 ).