ROSH Cardiovascular Flashcards
The electrocardiogram reveals a supraventricular tachycardia (SVT). Most cases of SVT result from sustained reentry occurring within the atrioventricular (AV) node, with a minority of cases of SVT resulting from a reentry loop from an ectopic atrial focus. The electrocardiographic hallmarks of SVT are a fast, regular rhythm with a narrow QRS complex. Since the depolarization does not come from the sinoatrial node, P waves do not precede each QRS complex, though P waves may be buried within or seen immediately before or after each QRS complex, known as “retrograde” P waves. Paroxysmal SVT is more common in females than males, with a peak incidence in the late teenage and young adult years. Most patients with SVT do not have underlying heart disease. Common symptoms include palpitations, lightheadedness, and dyspnea. Vagal maneuvers, such as carotid sinus massage and valsalva, are often successful in terminating SVT, especially early in the dysrhythmia course. If vagal maneuvers are ineffective, what is the treatment of choice?
Adenosine. The initial dose of adenosine is 6 mg rapid intravenous push, followed by a dose of 12 mg if the first dose is ineffective. Beta-blockers and calcium channel-blockers are alternative agents. Electrical cardioversion is used for refractory SVT or patients who are clinically unstable. MOA is AV nodal conduction blockade.
