Chapter 39

The diagnosis and management of specific cardiac arrhythmias are detailed in other chapters in this textbook. This chapter provides the clinician with an approach to the overall evaluation of patients presumed to have a cardiac arrhythmia. Without a doubt, the two key elements in assessing patients are the history and, if available, the electrocardiogram (ECG) rhythm strip obtained at the time of their symptom. Findings on the physical examination and judicious use of noninvasive and invasive tests can be quite helpful in certain circumstances.

It is imperative that a complete history of the patient's symptoms be obtained. Many elements must be sought for in this process, including (1) documentation of initial onset of symptoms; (2) complete characterization of symptoms; (3) identifying conditions that appear to initiate symptoms; (4) duration of episodes; (5) frequency of episodes; (6) pattern of symptoms over time, for example, better or worse; (7) effect of any treatment; and (8) family history of a similar problem. It is also important to ascertain any pertinent past medical history that might be helpful in the diagnosis. This might include history of myocardial infarction (MI), especially in a patient who presents with palpitations and syncope, or the recent initiation of a drug that can cause hypotension, for example, an antihypertensive agent, in a patient who now presents with dizzy spells. In our experience, careful and thorough attention to obtaining the preceding information typically results in an efficient and focused approach to the patient's problem.

In patients with supraventricular tachycardia with a 1:1 atrioventricular (AV) conduction pattern, the differential diagnosis is typically between AV reentry (AVRT), AV node reentry (AVNRT), and atrial tachycardia (AT). Thorough history taking can often lead one to the correct diagnosis even in the absence of an ECG tracing. For example, the onset of tachycardia with bending over or squatting is often present with AVRT or AVNRT, but not with AT. Palpitations associated with or aggravated by caffeine are more likely due to sinus tachycardia than an arrhythmia. In the differential diagnosis between AVRT and AVNRT, onset of symptoms in a woman >50 years old clearly favors AVNRT as the diagnosis. In fact, a recent report analyzing clinical variables in paroxysmal supraventricular tachycardia (PSVT) concluded that older age of onset, female sex, and presence of neck palpitations during tachycardia supported the diagnosis of AVNRT.1 We have also noted that the rate of the spontaneous tachycardia contains diagnostic power in adults, and rates of ≥250 beats/min are almost always AVNRT and not AT or AVRT.

Observations from the physical examination are helpful primarily to define whether cardiovascular disease is present. For example, in a patient who presents with dizzy spells or syncope, the presence of orthostatic hypotension should alert the clinician to investigate whether this is the cause of the clinical symptoms. However, presence of a carotid bruit or decreased peripheral pulses may be important findings related to atherosclerosis that lead to a workup of ...

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