A Tachycardic Synopsis of AFP's "Common Types of Supraventricular Tachycardia: Diagnosis and Management "

A brief synopsis of:
Common Types of Supraventricular Tachycardia: Diagnosis and Management 
RANDALLA.COLUCCI, DO, MPH, Ohio University College of Osteopathic Medicine, Athens, Ohio
MITCHELL J. SILVER, DO, McConnell Heart Hospital, Columbus, Ohio
JAY SHUBROOK, DO, Ohio University College of Osteopathic Medicine, Athens, Ohio http://www.aafp.org/afp/2010/1015/p942.html 
Am Fam Physician. 2010 Oct 15;82(8):942-952.


     Besides atrial flutter and fibrillation, there are three common types of SVT. They are AVNRT (AV nodal reentrant tachycardia), AVRT (AV reciprocating tachycardia), and AT (atrial tachycardia). 
     Nodal reentry is the most common type. It is seen in young, healthy women. The reentry occurs inside the AV node itself. The signal takes a slow route down the node (antegrade), and then a fast path back up it (retrograde). A "retrograde P wave" may not be seen on the ECG, but if it is, it will appear as a "pseudo R wave in lead V1".
     AV reciprocating tachycardia occurs shen the impulse passes through the AV node but instead of going to the bundle of his and around the apex of the ventricle, it follows an accessory "short cut"  through part of the heart and back to the AV node. This creates a reentry circuit and a short RP interval, which will vary depending on the specific trail of the shortened path. A delta wave may be seen. The patient may also develop spontaneous atrial fibrillation. 
   AT is caused by a signal being created in a place other than the SA node, commonly "adjacent to the crista terminalis in the right atrium or the crista terminalis in the right atrium". It can also be multifocal. 
     The most common symptoms in SVT are chest discomfort, dyspnea, fatigue, lightheadedness, and palpitations  The palpitations are intermittent. The patient may be told that they have anxiety or panic disorder. Tachycardia may be the only sign in an otherwise normal patient. The history may show symptoms since childhood, onset with coffee, stress, or lack of sleep, or a positive family history. An ECG may show a narrow QRS complex, prolonged QT interval, or delta waves. A wide complex tachycardia may be associated with a bundle branch block. 
     Management can be divided into short and long term, depending on whether the symptoms come and go, or if they are more serious, causing syncope, hemodynamic instability or other dangerous symptoms. Short term management can be performed first by nonpharmacologic treatments such as the valsalva maneuver, vagal maneuvers, or carotid massage (unless the patient may have an atherosclerotic plaque). This will increase vagal tone and decrease heart rate. Pharmacologic treatments include adenosine or verapamil. Adenosine may cause ventricular fibrillation in patients with Wolff-Parkinson-White syndrome.  It is an AV node blocking agent and thus would not work with AT. Verapamil can be used if adenosine does not correct the SVT. It is a negative inotrope,  so it may cause bradycardia and vasodilation. If none of these treatments work, then referral to a cardiologist for treatment with flecainide or propafenone may be necessary. 
     Long term management is considered, depending on frequency, intensity, and quality of life. The options are radiofrequency catherter ablation or intermittent medication. If the patient only experiences episodes a few times a year, they can be given verapamil PRN, known as the "pill-in-a-pocket" method. Ablative therapy has recently been shown to be quite effective with better long term outcomes and cost.