R

radiofrequency ablation A therapeutic proce-
dure to treat ARRHYTHMIAdisorders such as WOLFF-
PARKINSON-WHITE SYNDROME or PAROXYSMAL ATRIAL
TACHYCARDIA (PAT). Radiofrequency ablation uses
high-frequency energy, similar to microwave
energy, to destroy abnormal electrical pathways in
the HEART. The cardiologist performs radiofre-
quency ablation via CARDIAC CATHETERIZATION,
threading a catheter through a blood vessel and
into the heart. Electrodes on the tip of the
catheter function somewhat as an ELECTROCARDIO-
GRAM(ECG), sending information about the heart’s
electrical activity via the catheter back to a moni-
tor. When the catheter reaches the area of dys-
functional electrical activity, the cardiologist sends
a burst of high-frequency energy through the
electrodes. The energy destroys the area of
myocardial tissue responsible for the dysfunction,
closing the abnormal electrical pathway. The
heart’s regular electrical pathways then become
the route for the heart’s electrical pacing impulses.
Radiofrequency ablation permanently ends the
arrhythmia about 90 percent of the time.
See also ATRIOVENTRICULAR (AV) NODE;
IMPLANTABLE CARDIOVERTER DEFIBRILLATOR(ICD); PACE-
MAKER; SINOATRIAL(SA) NODE.

Raynaud’s syndrome A condition in which the
smallest arteries, the arterioles, in the hands and
the feet spasm in response to cold. The spasm
interrupts the flow of BLOODto the fingers and
toes, depriving them of oxygen. Raynaud’s syn-
drome may be idiopathic (without identifiable
cause) or secondary to other health conditions
(notably connective tissue disorders). Raynaud’s
syndrome may also develop as a SIDE EFFECTof cer-
tain medications such as vasoconstrictors (drugs
that cause the blood vessels to constrict). Cigarette

smoking is often a precipitating factor and wors-

ens symptoms. Some doctors use the terms Ray-

naud’s diseaseto identify idiopathic Raynaud’s and

Raynaud’s phenomenonto identify secondary Ray-

naud’s.

POSSIBLE CAUSES OF RAYNAUD’S SYNDROME

cigarette smoking dermatomyositis

electrical shock ergot medications

FROSTBITEorHYPOTHERMIA long-term exposure to

PERIPHERAL VASCULAR DISEASE(PVD) vibration

RHEUMATOID ARTHRITIS REPETITIVE MOTION INJURIES

SPINAL CORD INJURY SCLERODERMA

SYSTEMIC LUPUS ERYTHEMATOSUS(SLE)

The doctor generally makes the diagnosis on

the basis of the pattern of symptoms, which is dis-

tinctive and consistent. The pattern includes three

phases most easily identified according to the

color of the fingers or toes:

1. Cold causes the arterioles to spasm, depriving
   the fingers or toes of oxygen. The fingers or
   toes turn white.


2. The veins and capillaries dilate, flooding the tis-
   sues with deoxygenated blood. The fingers or
   toes turn blue (CYANOSIS) and typically feel
   numb.


3. With warmth the arterioles will relax, which
   restores the flow of circulation and floods the
   fingers or toes with oxygenated blood. The fin-
   gers or toes turn deep red, and may throb and
   feel hot.

The most effective treatment for Raynaud’s

syndrome is keeping the fingers and toes warm to

prevent the arterioles from spasming. When an

attack occurs, warming the fingers or toes gener-

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