Which clinical history findings are characteristic of sinus node dysfunction (SND)?

Updated: Nov 30, 2018
  • Author: Bharat K Kantharia, MD, FRCP, FAHA, FACC, FESC, FHRS; Chief Editor: Mikhael F El-Chami, MD  more...
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Symptoms are frequently intermittent with gradual progression in frequency and severity, although some patients may present with profound, persistent symptoms. Rarely, patients with SND may be asymptomatic and identified on routine electrocardiography (ECG) or ambulatory ECG monitoring.

Patients with symptomatic SND are usually older with frequent comorbid diseases; they often seek medical attention owing to symptoms of lightheadedness, presyncope, syncope and, in patients with alternating periods of bradycardia and tachycardia, palpitations and/or other symptoms associated with a rapid heart rate.

Patients with coexisting cardiac pathologies such as valvular or ischemic heart disease may notice increasing dyspnea on exertion or worsening chest discomfort related to a lower heart rate and the resulting reduction in cardiac output. Because symptoms may be variable in nature, nonspecific and, frequently, transient, it may be challenging at times to establish this symptom-rhythm relationship. Atrial arrhythmias appear to develop slowly over time, possibly the result of a progressive pathologic process that affects the sinoatrial (SA) node and the atrium. [29]

Prior to any testing beyond an ECG, a thorough clinical evaluation should be performed for potentially reversible causes, which include medication use (eg, beta blockers, calcium channel blockers, digoxin, antiarrhythmics), myocardial ischemia, systemic illness (eg, hypothyroidism), and autonomic imbalance.

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