Case 25: A 75-Year-Old Woman with Palpitations
A 75-year-old woman presents to the Emergency Department with a two hour history of palpitations, dyspnea, and weakness. She reports no previous cardiac issues:
- Atrial tachycardia with Mobitz I second degree AV block – atrial rate 172/min, ventricular rate 154/min
- Minimal voltage criteria for left ventricular hypertrophy (R in V6 + S in V1 = 38 mm)
- Marked ST abnormality, consider anterolateral ischemia
The 10 seconds strip of lead V1 is the best for the interpretation of this arrythmia.
Do you see P waves? Yes – Are the P waves regular? Yes – What is the atrial rate? 172/min —> Atrial tachycardia
Are all P waves followed by a QRS? – No, four P waves are not conducted —> second degree AV block
Is the PR constant? No, the PR gradually increases until AV block occurs (Mobitz I)
What is the ventricular rate? 154/min. Is the QRS pattern constant? Yes
Conclusion: Atrial tachycardia with Mobitz I second degree AV block – atrial rate 172/min, ventricular rate 154/min
Thirty minutes after arrival, the arrhythmia spontaneously subsides and the patient becomes symptom-free. Physical examination, chest xray, and echocardiogram are all normal. The patient is discharged with a referred to her family physician for further follow-up. The following ECG was recorded prior to discharge, four hours after her arrival:
- Sinus rhythm, 85/min
- Normal ECG
ECG ID: E706