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  1. Which patients with bradyarrhythmias require admission to the hospital?

  2. When does the bradyarrhythmic patient require a cardiology consult?

  3. Which bradyarrhythmic patients require permanent pacemaker placement?

Bradyarrhythmia is a common finding in hospitalized patients. It can be of minimal prognostic significance or can indicate a serious cardiac condition that requires immediate attention. Broadly speaking, bradyarrhythmias are caused by depression of sinus node activity or conduction system blocks. Symptoms depend on the patient's co-morbidities, the anatomical basis for the block(s), and the location of the subsidiary pacemaker which must take over to maintain cardiac output. Clinicians must analyze historical data, and examine the patient for evidence of hypoperfusion and electrocardiographic data to determine the likelihood that the rhythm will deteriorate into a worsening bradycardia or ventricular asystole.

Epidemiology

A heart rate below 60 beats per minute defines bradycardia. Resting heart rates vary among normal individuals and depends upon age and level of conditioning. One study demonstrated that resting heart rates can range from 46 to 93 beats per minute in males and 51 to 95 beats per minute in females. Additionally, heart rate varies with time of day. Heart rate during sleep may decrease between 14 and 24 beats per minute (bpm) on average, depending upon age. Due to this variability, it is difficult to fully assess the incidence and prevalence of bradycardia in the general population. Asymptomatic bradycardia portends no adverse prognostic significance in healthy individuals, including those over 40 years old.

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Practice Point
  • Heart rate while sleeping can decrease between 14 and 24 beats per minute on average. As a result, normotensive individuals normally experience a nocturnal dip in their blood pressure.

Sick sinus syndrome, or sinus-node dysfunction, however, does impact morbidity and mortality. The prevalence of sick sinus syndrome is estimated at 1 in 600 patients over 65 years old. Many patients with sick sinus syndrome have an elevated risk of cardiovascular events, including syncope, heart failure, and atrial fibrillation. Mortality for untreated patients with sick sinus syndrome ranges from 5 to 10% at 1 year to 25 to 30% at 5 years.

Presentation

Even a significant sinus bradycardia may not produce symptoms, depending on an individual's age, physical conditioning, and co-morbidities. In these patients the bradycardia may be identified as an ECG abnormality (sinus bradycardia, sinus arrest, exit block, or alternating with a tachyarrythmia). The elderly and patients with co-existing cardiopulmonary disease are more likely to develop symptoms related to low perfusion (presyncope, fatigue, weakness, confusion) or to associated tachycardia (palpitations, angina, heart failure). See (Table 127-1).

Table 127-1 Symptoms of Bradyarrhythmia

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