Managing Ventricular Tachycardia: Total Atrioventricular Block After Ablation in a Patient with Nonischemic Dilated Cardiomyopathy

History

In September 2000 the patient was referred to a cardiologist because of premature ventricular contractions. The 12-lead surface electrocardiogram (ECG) showed sinus rhythm with atypical right bundle branch block (RBBB), a fragmented QRS, and negative T-waves in III, aV _F and V _1-3 . Echocardiography, a 24-hour Holter ECG, and stress test were reported to be unremarkable. An expectant strategy was adopted.

In December 2009 the patient was hospitalized for sustained monomorphic ventricular tachycardia, with a heart rate of 254 bpm. A coronary angiogram did not show atherosclerosis. Magnetic resonance imaging (MRI) revealed marked thinning and hypokinesia of the basal anterior and anteroseptal wall. The left ventricular end-diastolic volume was 169 mL, left ventricular ejection fraction (LVEF) was 48%. Right ventricular volumes and systolic function were normal. An implantable cardioverter-defibrillator (ICD) was implanted, complicated by pneumothorax.

The patient experienced life-threatening electrical storm as a result of recurrent sustained monomorphic ventricular tachycardia in June 2010. When the emergency service arrived, the twelfth ICD shock was administered for monomorphic ventricular tachycardia resulted in ventricular fibrillation, and the patient lost consciousness. ICD therapy was disabled by a magnet and the patient resuscitated. After successful external defibrillation, acute ventricular tachycardia recurrence was prevented by intravenous amiodarone. However, despite amiodarone, ventricular tachycardia recurred during admission in her local hospital. The patient was referred for ventricular tachycardia ablation.

The patient’s cousin died suddenly at the age of 37. At autopsy a pale and mottled heart was found.

Current Medications

The patient was taking thiamazole 30 mg daily, metoprolol Zoc 100 mg twice daily, calcium carbasalate (Ascal) 100 mg daily, ramipril 2.5 mg daily, oxazepam 10 mg three times daily, and clorazepate 5 mg if needed.

Current Symptoms

The patient received 12 ICD shocks for monomorphic ventricular tachycardia. In the hospital the patient was highly anxious because of the multiple ICD shocks. She did not report chest pain or dyspnea on exertion. The history was otherwise unremarkable.

Physical Examination

• BP/HR: 115/65 mm Hg/77 bpm

• Height/weight: 172 cm, 68 kg

• Neck veins: Not distended

• Lungs/chest: Unremarkable

• Heart: No murmurs

• Abdomen: Unremarkable

• Extremities: No peripheral edema, peripheral pulses intact in both groins, no murmurs

Laboratory Data

• Hemoglobin: 8.4 mmol/L

• Hematocrit/packed cell volume: 40%

• Mean corpuscular volume: 82 fL

• Platelet count: 216 × 10 ³ /µL

• Sodium: 140 mmol/L

• Potassium: 4.3 mmol/L

• Creatinine: 56 μmol/L

• Blood urea nitrogen: 3.3 mmol/L

Electrocardiogram

The ECG recorded sinus rhythm ( Figure 26-1 ) and sustained monomorphic ventricular tachycardia ( Figure 26-2 ) on the first day of admission at the cardiac care unit of the referring hospital.

Echocardiogram