Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Supraventricular Tachycardia (SVT, PSVT) Medical Treatment
If a person has low blood pressure, chest pain, or a failing heart with tachycardia, the condition is considered unstable. In such cases, the person may be in serious danger and need immediate treatment. They may need an electrical shock (cardioversion) to convert their heart to a normal rhythm. This is considered an emergency. Synchronized cardioversion, usually first attempted with a 50 joule shock, can be done with a defibrillator at the bedside with all emergency materials available (a resuscitation or “crash” cart) and ancillary personnel to help if the patient remains unstable or their condition deteriorates. Although this occurs infrequently with PSVT, it is best to be prepared.
If a person's condition is stable, a number of options are available to end the abnormal rhythm:
Vagal maneuvers: Coughing, holding the breath, immersing the face in cold water, and tensing abdominal muscles as if having a bowel movement are called vagal maneuvers because they increase the tone of the vagus nerve on the heart. Increased vagal tone stimulates release of substances that decrease the heart rate, which in some people, can break the abnormal electrical circuit and stop PSVT.
Carotid massage: Carotid massage can release chemicals to slow the heart rate. Carotid massage is generally limited to young, healthy people because older people are at risk for stroke. In the emergency department, the patient will be connected to a heart monitor because the decrease in heart rate can be dramatic. Carotid massage involves gently pressing and rubbing the carotid artery located in the neck just under the angle of the jaw.
Medications: Patients may be given adenosine (Adenocard), a short-acting medication that decreases the heart rate by blocking the SA node conduction for a few seconds. This medication is given by IV to act quickly. Adenosine has some temporary side effects, including facial flushing, chest pain, shortness of breath, nausea, and dizziness. If a single dose does not stop supraventricular tachycardia, then the doctor may give higher doses. Adenosine successfully stops paroxysmal supraventricular tachycardia (PSVT) of all types in more than 90% of cases.
Other medications: If adenosine is unsuccessful, other medications can be used, such as calcium channel blockers (diltiazem), digoxin (Lanoxin), or beta-blockers (esmolol). Blood pressure is monitored carefully with these drugs.
A doctor, usually a cardiologist, will devise a treatment that treats the specific cause of supraventricular tachycardias. The following treatments are infrequently used for PSVT but may be necessary depending on the severity of the patient's symptoms and their overall health condition:
Pacemaker: A pacemaker is an electronic device that takes over the role of the SA node as pacemaker of the heart. It is often implanted inside the heart by a cardiologist or an electrophysiologist in the cardiac catheter lab, or by a surgeon.
Other treatments: In special cases, the source of the arrhythmia or abnormal electrical pathways can be interrupted by chemicals, ablated by high frequency energy through a catheter [such as in patients with regular recurrent PSVT or the Wolff-Parkinson-White (WPW) syndrome], or by a surgeon; but this is done infrequently for PSVT.