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Maze III Procedure for Atrial Fibrillation
Atrial fibrillation is an abnormality of the electrical system of the
heart. Normally, the heartbeat is triggered by an electrical impulse
which starts in the Sinoatrial (SA) node. The electrical signal to
contract starts in the SA node and normally moves evenly across the atrium,
triggering it to contract all at once. The impulse then travels across
the atrioventricular ( AV ) nodeand triggers the ventricles (the main pumping
chambers of the heart) to contract. This is called sinus
rhythm. Atrial
fibrillation occurs when this electrical impulse no longer travels from
SA node to the AV node in the normal manner. Instead of the impulse traveling
evenly across the atrium straight from the SA node to the AV node, the
impulse is "side-tracked" such that the atrium is no longer triggered
evenly and in synchrony, but is triggered one small region at a time.
ATRIAL FIBRILLATION CAUSES
A variety of conditions can lead to atrial fibrillation. The most common cause
of atrial fibrillation is simply aging. Our risk of atrial fibrillation increases
as we grow older and areas of scarring or fibrosis develop in our atrial
tissue as a result of simple "wear and tear." Abnormalities of
the valves in the heart, most often the mitral valve, can also cause "wear
and tear" and lead to atrial fibrillation. Some specific conditions,
such as thyroid disease, may be treatable with medications alone. In a small
number of cases, atrial fibrillation appears to be inherited - which is to
say that it runs in some families - while in many cases its cause is unknown.
SYMPTOMS OF ATRIAL FIBRILLATION
Atrial fibrillation results in : An irregular heartbeat that may be too slow
at times, and racing at others. Loss of the atrial contraction that normally
contributes to filling of the ventricle (the main pumping chamber of the
heart) and improves pump performance. Abnormal flow of blood through the
atrium with areas of stagnation which increase the risk of clot formation
and stroke. Lethargy and fatigue are also common symptoms in patients with
atrial fibrillation.
THE MAZE III PROCEDURE
The surgical procedure consists of creating a number of incisions in the atrium
that disrupt the abnormal circuits. Once the incisions are made, they are
sewn together again. The atrium can then hold blood on its way to the ventricle
and can squeeze or contract to push the blood in to the ventricle, but the
electrical impulse cannot cross the incisions. The result is what looks like
a maze in which there is only one path that the electrical impulse can take
from the SA node tothe AV node. The atrium can no longer fibrillate, and
sinus rhythm (the normal rhythm of the heart) is restored.
INDICATIONS
The Maze procedure is not necessary in most patients with atrial fibrillation.
Many patients are not bothered by the rhythm or the medications required
to control it. In some cases, cardiologists are able to disrupt the circuits
with catheters. Some patients, however, are so troubled by the way they feel
when they are in atrial fibrillation or by the medications they must take
that a surgical option is appropriate. In addition, individuals in atrial
fibrillation who have experienced a stroke are at significant risk for another
stroke. The MAZE procedure may be indicated in these individuals as well.
The "Mini-Maze" procedure is a new endoscopic
way of treating certain types of atrial fibrillation resulting in reduced
incisional pain and recovery time.
RISKS
The traditional Maze procedure is an "open heart" procedure requiring
cardiopulmonary bypass (the heart-lung machine. Accordingly, it carries risk
of stroke, kidney failure, other organ failure, and death. The risk of this
procedure is felt to be low in general, but the risk will be affected by each
individual's specific health conditions (heart function, lung function kidney
function, etc.). In addition, some patients require a permanent pacemaker postoperatively.
This is thought to be due to underlying disease of the SA node.
The endoscopic "Mini-Maze" procedure may
significantly reduce surgical risk with an average length of hospital stay
2-3 days.
RESULTS
The Maze procedure is highly effective in restoring sinus rhythm. Success rates
vary by center, but are generally reported in the range of 90-100%.
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