Palpitations and Arrhythmias (Case 6)

Arzhang Fallahi MD and Michael Kim MD

Case: A 75-year-old man with a history of hypertension and hyperlipidemia presents to the emergency department complaining of palpitations. He states that for the past day he has felt a strange feeling in his chest, like his heart is racing, and says he is mildly short of breath. He has had similar episodes in the past, but they went away with rest and tended to “come and go.” He reports some light-headedness. He denies any chest pain, cough, or history of thyroid disease. He has never seen a cardiologist before and has never had “serious heart problems.” His only medications are aspirin 81 mg, hydrochlorothiazide 25 mg, and simvastatin 40 mg, all taken once daily. There is no family history of heart disease. His pulse is 135 bpm, and his BP is 145/70 mm Hg. On exam he seems to be in no acute distress but appears anxious. He has clear lung fields bilaterally and an irregular heart rate with no obvious murmurs, rubs, or gallops and no elevated neck veins. He has trace edema in his lower extremities.

An ECG reveals a narrow complex tachycardia at 135 bpm, irregularly irregular with no P waves and no delta waves; aVL shows a QRS complex of 12 little boxes in height; no other ST elevations or depressions are noted.

Differential Diagnosis

Speaking Intelligently

The approach to a patient with palpitations is as follows:

1. Assess airway, breathing, and circulation with IV access, oxygen administration, and cardiac monitoring; with a 12-lead ECG; and with initial blood work (including troponin concentrations).

2. Clinically assess associated signs of the tachycardia: hypotension, heart failure or pulmonary congestion, shortness of breath, renal failure, shock, altered mental status, angina, or acute myocardial infarction. A quick assessment of vital signs must be made even before one takes a detailed history. Ultimately, is the patient stable or unstable? Arrhythmias such as ventricular tachycardia, ventricular fibrillation, or any heart rhythm with profound hypotension are a medical emergency, which may require immediate management.

3. The history of the palpitations is a key point. Is this new? Does the patient have a history of cardiac arrhythmias? Is the patient on any medications that may contribute? Are the palpitations associated with any chest pain? Is there any history of thyroid disease? The underlying cause of the tachycardia must be determined from the very outset. Is the patient having an acute coronary event? Does the patient have signs of heart failure or pulmonary disease? Is the patient hypo- or hypervolemic? Is the process acute or chronic in nature?

4. Assess for comorbidities: lung disease (asthma, chronic obstructive pulmonary disease [COPD], pulmonary hypertension, restrictive lung disease), cardiac disease, hypertension, age, diabetes, history of stroke. Comorbidities will help in risk-stratifying the patient, as well as in guiding management.

5. The tachyarrhythmia must be quickly assessed using the four main categories listed above to guide subsequent management.

PATIENT CARE

Tests for Consideration

• ECG is critical to obtain in all patients promptly. ECG can be used to categorize the type of tachyarrhythmia, which will help guide management.	$27
• Cardiac markers (serum troponins and/or CK-MB) are needed to determine if an acute coronary syndrome is precipitating the event.	$49
• Metabolic panel with thyroid-stimulating hormone (TSH), creatinine, and electrolytes will help determine if an underlying metabolic disturbance is resulting in cardiac dysfunction. An acute decompensation in renal function may be a sign of shock. A low TSH concentration may suggest hyperthyroidism.	$39
• Complete blood count: to determine if the patient has an underlying infection, which may contribute to the tachyarrhythmia. Hemoglobin and hematocrit are important to determine if the patient is anemic.	$11
• Liver function tests may be helpful to help ascertain if there is a hepatic cause of infection.	$12
• Coagulation tests are helpful to see whether the patient is prone to thrombosis or at high risk of bleeding. They are also helpful if the patient is to have a procedure, such as ablation to treat the arrhythmia.	$15
• A urine toxicology screen should be obtained in patients suspected of using illicit drugs as a precipitant of the arrhythmia.	$21

IMAGING CONSIDERATIONS

→ Chest radiography is helpful to see if any pulmonary disease or process such as a pneumonia, effusion, or pneumothorax is present. Cardiomegaly can be assessed, but quality may be suboptimal with a portable chest radiograph. Radiography can also help determine if there is a widened mediastinum, which may be suggestive of an aortic dissection.	$45
→ Echocardiography is helpful not only to assess ventricular and valvular dysfunction, but also possibly to help determine if there is a thrombus, which may embolize if the patient is cardioverted.	$393