A faster heart rate and numbness: Is the patient having a heart attack?
A 30-year-old woman presents with an increased heart rate, shortness of breath, and tingling in her right arm.
Etiology of supraventricular tachycardia
Supraventricular tachycardia (SVT) is a term that describes a group of heart arrhythmias with a rate greater than 100 beats per minute caused by an electrical impulse originating above the bundle of His.1 The incidence of SVT is 35 per 100,000 person-years with a prevalence of 2.29 per 1,000 persons excluding atrial fibrillation or atrial flutter and multifocal atrial tachycardia (AT).2 There are 3 main types of SVT that occur: atrioventricular nodal reentrant tachycardia (AVNRT), AT, and atrioventricular reciprocating tachycardia (AVRT).3,4 In adults, AVNRT is the most common type of SVT, and AVRT is the most common in children.1
AVNRT commonly affects young, healthy women without structural heart disease.5 Common tachycardic risk factors include drug induction, caffeine, prior history of heart disease, alcohol use, stress, anxiety, and other factors that potentially cause stress.
Triggers for SVT and increased heart rate must be differentiated from other similar conditions. Symptoms associated with SVT include chest discomfort or pressure, shortness of breath, fatigue, lightheadedness or dizziness, and palpitations.1 A positive previous history of heart disease (especially mitral valve prolapse, previous myocardial infarction, or pericarditis), young age, and female gender increase the risk for a diagnosis of SVT.1 Other risk factors of AVNRT include heavy caffeine intake, heavy alcohol use, illicit drug use, family history of tachycardia, medication induced, and extreme stress and anxiety. The patient needs to be queried regarding any potential risk factors and any past or present symptoms. This disease process has a tendency to be misdiagnosed as anxiety or panic disorder among patients with a psychiatric history.6
Physical examination in the diagnosis of SVT may or may not be helpful in determining the etiology of the presenting symptoms. Younger, presumably healthy individuals usually have normal findings during physical examination with a single abnormal finding of tachycardia.1
Workup of SVT
The focused exam should include the cardiovascular, respiratory, and endocrine systems. During the cardiovascular exam, a practitioner should auscultate carefully for murmur(s), friction rub, third heart sound, and cannon waves. These findings are significant in the diagnosis of valvular heart disease, pericarditis, heart failure, and specific types of tachycardia, which is the culprit for arrhythmias and other symptoms. A respiratory exam could reveal crackles that would lead to the diagnosis of heart failure as the precipitant of tachycardia. An endocrine exam will pinpoint or rule out hyperthyroidism or thyroiditis as the cause of tachycardia.1
The diagnostic workup office visit should include vitals, orthostatic blood pressure, blood work (complete blood count, thyroid stimulating hormone, basic metabolic panel, brain natriuretic peptide, and cardiac enzymes), and diagnostics (chest X-ray, Holter monitor or event recorder, graded exercise testing, and echocardiography [12 lead]).1 The EKG will determine if pre-excitation is present to differentiate AVRT from other causes of and types of tachycardia. Figure 1 shows how the diagnostic workup of a patient with suspected SVT should be performed.
Treatment of SVT
SVT treatment focuses on the cessation of active episodes. In individuals with frequent episodes and serious symptoms (pre-syncope and syncope), cessation is critical. Treatment is divided into short-term and long-term management.1
Short-term or urgent treatment may include the use of oral or intravenous antiarrhythmic drug therapy, vagal maneuvers, and electrical cardioversion for SVT.8 According to JAMA Cardiology and the 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia, initial treatment should begin with vagal maneuvers and/or adenosine.13 If the patient is hemodynamically stable, pharmacologic treatment (beta blockers, diltiazem, or verapamil) should be administered intravenously for immediate relief.13 If a patient is found to be hemodynamically unstable or pharmacologic intervention is not feasible, synchronized cardioversion is the treatment of choice.13