Palpitations in Young People: 2 ECG Challenges
Palpitations and syncope during dinner (him); arrhythmia that looks like SVT after 2 energy drinks (her). What do the ECGs tell you?
The Young and Restless at Heart
Patient history. A 32-year-old man is seen in the ED for palpitations followed by syncope that occured while eating. Other than "thyroid surgery" there is no significant PMH, no current meds. He claims of more muscle twitching than normal. Vital signs, normal; phyisical exam, normal other than scar noted above.
Intial ECG tracing is seen above and preliminary differential diagnosis includes:
- Dysrhythmia
- Dehydration
- Ischemia
- Electrolyte abnormality
ECG read, Dx, next steps. The ECG tracing shows a long QT interval and a short PR interval. Electrolytes are checked and reveal a alcium level of 5.8 mg/dL-diagnostic for hypocalcemia.
Hypocalcemia. Hypocalcemia is often asymptomatic, but can cause asthenia, muscle cramps, twitching or seizures; laryngospasm is of greatest concern. PE may be normal but look for hyperreflexia (eg, Chvostek’s sign, increased deep tendon reflexes). The ECG in hypocalcemia most typically reveals a prolonged QT interval but watch for short PR interval, long ST interval, and flat T-waves.
For the original case, including treatment options and case conclusion, please see ECG Challenge: Palpitations and Syncope in a Young Man
Patient history. A 32-year-old woman arrives at the ED via ambulance c/o palpitations after consuming 2 "energy" drinks. PMH includes congenital heart disease. Medics say she is in SVT but has not responded to adenosine 6 and 12 mg. On arrival she denies chest pain, SOB, or other complaints. She also denies recreational drug use.
Vital signs and physical exam. Vital signs, normal except for a pulse of 153 beats/min. PE normal, other than tachycardia. A 12-lead ECG performed in triage is read as SVT with a rate of 148 beats/min. Diagnostic test results: CBC, hCG, and basic metabolic panel, all normal.
Rhythm strip before / after adenosine 12 mg.
ECG read, next steps. The rhythm strip shows atrial flutter that is slowed by the adenosine, making it easier to see. The next step: Give a calcium channel blocker and consult cardiology and the hospitalist. Search for a cause of atrial flutter.
Atrial flutter. Atrial flutter can be regular or irregular depending on which of the flutter waves are conducted through to the ventricles. Flutter waves are typically close to 300 beats/min. Most commonly every other atrial depolarization is conducted (2-to-1 block) leading to a ventricular rate close to 150 beats/min. This can look similar to SVT and the ECG computer may interpret the atrial rhythm incorrectly. If the block is variable or higher level, like 3-to-1, then atrial flutter becomes much more obvious. Vagal maneuvers or AV nodal blockers like adenosine or diltiazem can accomplish this and confirm the diagnosis.
For original full case, treatment, and case conclustion, please see: Arrhythmia after an Energy Drink: SVT?
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