Introduction
Palpitations, defined as a subjective unpleasant awareness of heart beating, are a common symptom in pregnancy. Several physiologic alterations in pregnancy may exacerbate palpitations (Box 40.1). In addition, the increased awareness that a pregnant woman has of her body, concern about fetal well-being and more frequent contact with healthcare providers may make pregnant women more likely to report palpitations. Although most cases of palpitations in pregnant women will have a benign etiology, their benign nature should not be immediately assumed as palpitations may sometimes be a clue to a more serious underlying cause such as cardiac arrhythmia or thyrotoxicosis.
Sinus tachycardia, while not a normal finding in pregnancy, is a common finding that may present as palpitations. Sinus tachycardia can be a sign of conditions such as thyrotoxicosis, anemia, fever, pulmonary embolus, hypoglycemia, medications or illicit drug use. Obese pregnant women are more likely to be tachycardic, presumably due to deconditioning [1]. Premature atrial or ventricular beats are also common during pregnancy [2]. Although most cases are of little clinical significance and do not warrant treatment in and of themselves, the ectopic beats may represent underlying cardiomyopathy, ischemia or electrolyte disturbances and these etiologies should be considered if the clinical picture suggests the possibility of these conditions. Notably, women with ectopic beats are more likely to sense the compensatory pause after the premature beat than the premature beat itself.
Box 40.1 Physiologic changes in pregnancy that increase the likelihood of palpitations
- Increased stroke volume and cardiac output
- Increased heart rate by an average of 15 beats/minute
- Increased ectopic beats (atrial and ventricular)
- Increased catecholamine levels in pregnancy
- Increased sensitivity of the heart to catecholamines (from effect of estrogen)
- Rotation of the heart closer to the chest wall such that the sensation of the heart beating is felt more readily
More serious rhythm disturbances may be unmasked during pregnancy because of the physiologic changes that occur to the cardiovascular system. Arrhythmias may present for the first time during pregnancy [3] or may represent a previously unrecognized problem that is now occurring more frequently [4]. These rhythms may be supraventricular (e.g. paroxysmal supraventricular tachycardia (PSVT), atrial fibrillation or flutter) tachycardia or, less commonly, ventricular tachycardia. These arrhythmias may be due to underlying causes such an accessory pathway (e.g. Wolff-Parkinson-White syndrome causing a PSVT), structural heart diseases (e.g. obstructive cardiomyopathy, peripartum cardiomyopathy, valvular heart disease), congestive heart failure or ischemic heart disease [5].
The challenge to healthcare providers is to distinguish benign causes of palpitations from serious ones. A targeted history, physical exam and several key investigations can help in this process. The following is an approach to assessing palpitations in pregnancy.
- Ask the patient to count her heart rate during an episode and have her attempt to tap out the rhythm with her fingers on a table. Ask about the duration and frequency of episodes and whether the rhythm is irregular or regular. Irregular heart beats of less than 5 minutes in duration that are unassociated with lightheadedness or underlying cardiac disease are very likely to be benign. Description of an irregular heartbeat and/or duration of palpitations >5 minutes are more suggestive of a cardiac etiology [6]. Certain heart rates and rhythms may suggest specific diagnoses (Figure 40.1).
- Ask how the palpitations start and end – abruptly or gradually? When palpitations begin and end abruptly, they are often due to paroxysmal tachycardia (i.e. atrial or junctional), atrial flutter or atrial fibrillation. Alternatively, if the palpitations have a gradual onset and gradual cessation, it may suggest sinus tachycardia or an anxiety disorder as the cause.
- Ask about associated symptoms and events: the presence of syncope, chest pain or angina, anxiety or an exertional precipitant may suggest certain diagnoses (Table 40.1
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