A 40-year-old woman has Ebstein’s anomaly and right-sided heart failure. In the past year, she has had periodic episodes of a rapid heart rate; these have increased in frequency in the past two months. According to the patient, these episodes occur spontaneously without provocation, last for approximately 10 to 15 seconds, and are now an almost daily occurence. Severe lightheadedness and dyspnea accompany each episode. She has never had syncope.
The patient’s most recent echocardiogram documented Ebstein’s anomaly with severe tricuspid valve regurgitation, severe right ventricular dilatation, moderate left ventricular dysfunction, moderate mitral valve regurgitation, and a left ventricular ejection fraction of 35%. Medical history is remarkable for hypothyroidism, ascites secondary to right-sided heart failure, and chronic renal insufficiency.
The patient is gainfully employed and married, and she does not smoke or drink. Current medications include torsemide, warfarin, digoxin, spironolactone, levothyroxine, and potassium chloride. She has no known drug allergies.
The review of systems is positive only for some increase in abdominal girth over the preceding month. She denies shortness of breath, chest pain, orthopnea, dyspnea on exertion, peripheral edema, diarrhea, abdominal pain, nausea, vomiting, joint pain or swelling, or pregnancy. Her last menstrual period began four days ago. She denies headaches, seizures, or mental status changes.
Physical examination reveals a weight of 189 lb; height, 68”; blood pressure, 120/80 mm Hg; pulse, 70 beats/min; respiratory rate, 16 breaths/min; and O2 saturation, 95% on room air. Her temperature is 98.9°F. She is a very pleasant woman in no distress and is alert and oriented.
Pertinent physical findings include bounding jugular venous pulses with the jugular venous pressure at the angle of the jaw. The lungs are clear to auscultation bilaterally, and the cardiac exam is remarkable for an irregular pulse at a rate of 70 beats/min with a grade III/VI holosystolic murmur best heard at the apex. The abdomen is soft and nontender, with mild to moderate ascites present. The extremities are warm with no edema, cyanosis, or clubbing. The neurologic exam is grossly intact without focal signs.
An ECG is obtained and reveals the following: a ventricular rate of 70 beats/min; PR interval, 186 ms; QRS duration, 152 ms; QT/QTc interval, 512/553 ms; P axis, –1°; R axis, 106°; and T axis, –65°. What is your interpretation of this ECG?