Situations in which SVT can be dangerous

Situations in which SVT can be dangerous

Usually supraventricular tachycardia is an arrhythmia which is well tolerated and patients seldom go into hemodynamic compromise with SVT. But in certain situations, SVT can be dangerous, if it is associated with other conditions.

Such conditions include:

1. Hypertrophic cardiomyopathy – a fast rate shortens diastole and diastolic filling time for the left ventricle. A left ventricle with severe diastolic dysfunction in hypertrophic cardiomyopathy becomes underfilled and cardiac output falls, leading to hypotension. Flash pulmonary edema can also occur due to elevated left ventricular filling pressures. Simultaneous atrial and ventricular activation as occurs in atrioventricular nodal reentry tachycardia (AVNRT) causes more severe hemodynamic compromise [1].
2. Acute coronary syndrome  (ACS) – increased myocardial oxygen demand due to tachycardia worsens myocardial ischemia.
3. Inoperable severe coronary artery disease – increased myocardial oxygen demand worsens ischemia and they can go in for cardiac failure and hypotension,
4. SVT requiring high dose antiarrhythmic agent for suppression – severe bradycardia can occur after termination of SVT, due to the persistent effect of the antiarrhythmic agent. That is why when high dose beta blockers or non dihydropyridine calcium channel blockers are needed for suppression of tachyarrhythmias, a back up pacemaker is considered.

Reference

1. Ebrille E, Contreras-Valdes FM, Zimetbaum PJ. Hemodynamic response to supraventricular tachycardia in a patient with hypertrophic cardiomyopathy. HeartRhythm Case Rep. 2018 Dec 23;5(4):191-195.