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Figure 17-2. Diagrammatic comparison of normal and abnormal cardiac rhythms (Note: Interval ab =
interval bc)
MostepisodesofPSVTresolvespontaneously.Theindividualshouldrestuntiltheepis-
ode has ended. If the episode persists beyond a few minutes, a few simple maneuvers to
halt the episode may be attempted. All these maneuvers should be performed with the per-
son sitting or lying down. The Valsalva maneuver—bearing down as if straining to have a
bowel movement—may break the rhythm. Similarly, gagging by inserting a tongue blade
to the back of the throat may stop the rhythm. Immersion of the hand in ice water to the
point of pain occasionally works. The face can be immersed in ice water or cooled with a
wash cloth wet with icy water. If these maneuvers fail, massage of the right carotid artery,
gently at first and then more firmly if needed may resolve the tachycardia.
If the individual has lost consciousness, a more serious form of tachycardia, such as
ventricular tachycardia (a fast rhythm from the lower chambers), is implicated. Uncon-
sciousness should prompt a sharp blow or karate chop delivered to the midpoint of the
sternum (precordial thump).
PSVT has a tendency to recur. It is rarely life threatening and does not imply other car-
diovascular problems such as coronary artery disease. An episode that has been prolonged,
hasbeen difficult tocontrol, orisassociated with significant chest discomfort, may prompt
evacuation.
Atrial Fibrillation
Atrial fibrillation (AF) is a rapid but irregular heartbeat. The heart rate may be 100 to
180 per minute, and the onset may be sudden and resemble PSVT. The important differ-
ence is the totally irregular rhythm of atrial fibrillation. Careful palpation of the pulse and
listening to the heart may be necessary to be sure of the irregularity. At rates exceeding
160beatsperminute,irregularitiesaredifficulttodetect.Restshouldbeinstituted.Seventy
percentofallepisodesofatrialfibrillationresolvespontaneouslywithintwenty-fourhours.
The symptoms associated with atrial fibrillation are essentially the same as those of PSVT.
Maneuvers that stop PSVT may not be of value for atrial fibrillation. If the attack does not
respond to rest and sedation within twelve to twenty-four hours, the individual should be
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