A 68-year-old woman presents to the emergency department with chest pain, dizziness, and shortness of breath for the past 3 hours. She denies fever, nausea, vomiting, diaphoresis, or palpitations. Her past medical history consists of myocardial infarction one week prior as well as hyperlipidemia, stage 2 chronic kidney disease (CKD), and hypertension. Current medications include atorvastatin, ticagrelor, aspirin, valsartan, and metoprolol which have all been taken consistently at appropriate doses. Her family history includes atrial fibrillation and myocardial infarction at 75 years old in her father. She does not drink alcohol, smoke cigarettes, or use any recreational drugs. Vital signs are temperature 37.1° C (98.6° F), blood pressure 78/42 mmHg, pulse 125 beats/min, 97% O2 saturation, and respirations 18/min. On physical examination, she exhibits distension of the jugular veins, faint heart sounds on auscultation with no gallop or murmurs, and 1+ pitting edema in the legs to the level of the shins.
Which of the following findings is most likely to be seen on the patient’s electrocardiogram?
- A) Low voltage QRS complexes with alternating heights
- B) Presence of U waves
- C) Prolonged QT intervals
- D) ST segment elevations in the anterolateral leads
- E) T wave inversions
A) Low voltage QRS complexes with alternating heights
This woman is experiencing cardiac tamponade, displaying Beck’s triad of hypotension, jugular venous distension, and faint heart sounds. Characteristic ECG findings for this condition include low voltage QRS complexes with electrical alternans (varying heights of the QRS complexes). This patient experienced a myocardial infarction one week prior, likely leading to pericarditis or free wall rupture which developed into cardiac tamponade.
Answer choice B: Presence of U waves, is incorrect. U waves can be a sign of hypokalemia which can lead to serious cardiac arrhythmias.
Answer choice C: Prolonged QT intervals, is incorrect. A prolonged QT interval can lead to arrhythmias such as torsades de pointes but is not generally associated with tamponade.
Answer choice D: ST segment elevations in the anterolateral leads. ST segment elevations would be seen in an acute myocardial infarction affecting the lateral wall of the left ventricle as a result of blockage in the left anterior descending coronary artery. A U wave can be a sign of hypokalemia, involved in serious arrhythmias as well.
Answer choice E: T wave inversions, is incorrect. T wave inversions also would be seen in an acute myocardial infarction.
Key Learning Point
Cardiac tamponade classically presents with Beck’s triad of hypotension, jugular venous distension, and faint heart sounds. Characteristic findings on electrocardiogram include low voltage QRS complexes with electrical alternans (variation in the amplitude or axis of the QRS complexes between heartbeats).