37 - 45 Palpitations

45 Palpitations

Joseph Loscalzo

Palpitations Palpitations are extremely common among patients who present to their internists and can best be defined as a “thumping,” “pounding,” or “fluttering” sensation in the chest. This sensation can be either inter­ mittent or sustained and either regular or irregular. Most patients inter­ pret palpitations as an unusual awareness of the heartbeat and become especially concerned when they sense that they have had “skipped” or “missing” heartbeats. Palpitations are often noted when the patient is quietly resting, during which time other stimuli are minimal. Palpita­ tions that are positional generally reflect a structural process within (e.g., atrial myxoma) or adjacent to (e.g., mediastinal mass) the heart. Palpitations are brought about by cardiac (43%), psychiatric (31%), miscellaneous (10%), and unknown (16%) causes, according to one large series. Among the cardiovascular causes are premature atrial and ventricular contractions, supraventricular and ventricular arrhythmias, mitral valve prolapse (with or without associated arrhythmias), aortic insufficiency, atrial myxoma, myocarditis, and pulmonary embolism. Intermittent palpitations are commonly caused by premature atrial or ventricular contractions: the post-extrasystolic beat is sensed by the patient owing to the increase in ventricular end-diastolic dimension following the pause in the cardiac cycle and the increased strength of contraction (post-extrasystolic potentiation) of that beat. Regular, sustained palpitations can be caused by regular supraventricular and ventricular tachycardias. Irregular, sustained palpitations can be caused by atrial fibrillation. It is important to note that most arrhythmias are not associated with palpitations. In those that are, it is often useful either to ask the patient to “tap out” the rhythm of the palpitations or to take their pulse during palpitations. In general, hyperdynamic cardio­ vascular states caused by catecholaminergic stimulation from exercise, stress, or pheochromocytoma can lead to palpitations. Palpitations are common among athletes, especially older endurance athletes. In addi­ tion, the enlarged ventricle of aortic regurgitation and accompanying hyperdynamic precordium frequently lead to the sensation of palpita­ tions. Other factors that enhance the strength of myocardial contrac­ tion, including tobacco, caffeine, aminophylline, atropine, thyroxine, cocaine, amphetamines, and cannabis, can cause palpitations. Psychiatric causes of palpitations include panic attacks or dis­ orders, anxiety states, and somatization, alone or in combination. Patients with psychiatric causes for palpitations more commonly report a longer duration of the sensation (>15 min) and other accom­ panying symptoms than do patients with other causes. Among the miscellaneous causes of palpitations are thyrotoxicosis, drugs (see above) and ethanol, spontaneous skeletal muscle contractions of the chest wall, pheochromocytoma, systemic mastocytosis, and postCOVID syndrome. APPROACH TO THE PATIENT Palpitations The principal goal in assessing patients with palpitations is to deter­ mine whether the symptom is caused by a life-threatening arrhyth­ mia. Patients with preexisting coronary artery disease (CAD) or risk factors for CAD are at greatest risk for ventricular arrhythmias (Chap. 253) as a cause for palpitations. In addition, the associa­ tion of palpitations with other symptoms suggesting hemodynamic compromise, including syncope or lightheadedness, supports this diagnosis. Palpitations caused by sustained tachyarrhythmias in patients with CAD can be accompanied by angina pectoris or dyspnea, and, in patients with ventricular dysfunction (systolic or diastolic), aortic stenosis, hypertrophic cardiomyopathy, or mitral stenosis (with or without CAD), can be accompanied by dyspnea from increased left atrial and pulmonary venous pressure.

Key features of the physical examination that will help confirm or refute the presence of an arrhythmia as a cause for palpita­ tions (as well as its adverse hemodynamic consequences) include measurement of the vital signs, assessment of the jugular venous pressure and pulse, and auscultation of the chest and precordium. A resting electrocardiogram can be used to document the arrhyth­ mia. If exertion is known to induce the arrhythmia and accom­ panying palpitations, exercise electrocardiography can be used to make the diagnosis. If the arrhythmia is sufficiently infrequent, other methods must be used, including continuous electrocar­ diographic (Holter) monitoring; telephonic monitoring, through which the patient can transmit an electrocardiographic tracing during a sensed episode; loop recordings (external or implantable), which can capture the electrocardiographic event for later review; and mobile (self-monitoring) cardiac outpatient telemetry. Data suggest that Holter monitoring is of limited clinical utility, while the implantable loop recorder and mobile cardiac outpatient telemetry are safe and possibly more cost-effective in the assessment of patients with (infrequent) recurrent, unexplained palpitations. The use of a diary or an electronic marker to indicate the timing of palpitations sensed by the patient is essential for appropriate interpretation of these studies. Exercise Intolerance CHAPTER 46 Most patients with palpitations do not have serious arrhythmias or underlying structural heart disease. If sufficiently troubling to the patient, occasional benign atrial or ventricular premature con­ tractions can often be managed with beta-blocker therapy. Palpita­ tions incited by alcohol, tobacco, or illicit drugs need to be managed by abstention, while those caused by pharmacologic agents should be addressed by considering alternative therapies when appropri­ ate or possible. Psychiatric causes of palpitations may benefit from cognitive therapy or pharmacotherapy. The physician should note that palpitations are at the very least bothersome and, on occasion, frightening to the patient. Once serious causes for the symptom have been excluded, the patient should be reassured that the palpi­ tations will not adversely affect overall prognosis. ■ ■FURTHER READING Crossland S, Berkin L: Problem based review: The patient with palpitations. Acute Med 11:169, 2012. Jamshed N et al: Emergency management of palpitations in the elderly: Epidemiology, diagnostic approaches, and therapeutic options. Clin Geriatr Med 29:205, 2013. Martson HR et al: Mobile self-monitoring ECG devices to diagnose arrhythmias that coincide with palpitations: A scoping review. Healthcare (Basel) 7:E96, 2019. Sakh R et al: Insertable cardiac monitors: current indications and devices. Expert Rev Med Devices 16:45, 2019. Weinstock C et al: Evidence-based approach to palpitations. Med Clin North Am 105:93, 2021. Joseph Loscalzo, William M. Oldham

Exercise Intolerance Exercise intolerance is defined as the inability to perform physical activity at a level expected for a person of a given age, sex, body mass, and muscle mass. Reduced exercise tolerance is a common symptom of many chronic diseases, including ischemic heart disease, valvular heart disease, heart failure, chronic obstructive pulmonary disease, inter­ stitial lung disease, cystic fibrosis, pulmonary hypertension, stroke, neuromuscular disorders, and postinfection syndromes, and it reduces