ANN ARBOR, Mich., March 1 /PRNewswire/ -- In a study published this month
in the Journal of Thoracic and Cardiovascular Surgery, a group of surgeons
reported 10-year follow-up data on adult patients undergoing cardiac surgery
with cardiopulmonary bypass. They found that pH levels in the myocardium
(heart tissue) before aortic cross-clamping, during aortic cross-clamping, or
after aortic cross-clamping, were independently associated with long-term
patient survival. Aortic cross-clamping refers to the time during which the
heart is deprived of its natural blood supply while the patient is placed on
the heart-lung machine.
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In the study, cardiac surgeons at the VA Boston Healthcare System followed
a total of 496 adult patients who underwent valve replacement, coronary bypass
surgery, or both for an average of 10 years. During the surgery, they
monitored pH levels in the myocardium. Analysis of the data identified three
significant thresholds that affected long-term mortality: pH less than 6.63
before aortic cross-clamp, pH less than 6.73 at the end of cardiopulmonary
bypass, and integrated mean pH of less than 6.34 during the period of aortic
Raising the pH level from lower than threshold before aortic cross-clamp
to higher than threshold during clamping increased the median survival by
"This is the first documentation of the adverse impact of intraoperative
myocardial acidosis, and thus myocardial ischemia, on long-term patient
survival," explained Shukri Khuri, lead author of the study. Myocardial
acidosis, as measured with tissue pH electrodes, has been repeatedly shown to
be reflective of myocardial ischemia.
The study's authors hypothesize that because intraoperative myocardial
acidosis accelerates apoptosis (premature cell death) in the myocardium, it
may also contribute to post-operative congestive heart failure, one of the
leading causes of late mortality after cardiac surgery. They hope to
elucidate further the relationship between acidosis, apoptosis, and congestive
heart failure in ongoing studies.
"The degree of myocardial acidosis that is encountered during cardiac
surgery varies widely from one patient to the next, and in most cases is
unpredictable," states Dr. Khuri. "If the surgical team is monitoring
myocardial pH during the surgery, the surgeon can employ a number of different
protocols and maneuvers to reverse or avoid ischemic conditions."
Dr. Khuri has developed an intraoperative pH monitoring system in
cooperation with Terumo Cardiovascular Systems Corporation. The Khuri
Myocardial pH Monitoring System is available worldwide. For more information,
visit http://www.terumo-cvs.com/khuriph .
Khuri and coauthors published the study, "Intraoperative regional
myocardial acidosis and reduction in long-term patient survival," in the
Journal of Thoracic and Cardiovascular Surgery 2005;129:372-81.
Terumo Cardiovascular Systems Corporation manufactures and markets
products for the cardiac surgery, interventional, and neurovascular markets.
It is headquartered in Ann Arbor, Michigan with American manufacturing
operations in Ann Arbor, as well as Elkton, Maryland; Ashland, Massachusetts;
Tustin, California; and Matamoros, Mexico. It is one of several subsidiaries
of Terumo Corporation of Japan that are focused exclusively on the cardiac and
vascular markets, including: Vascutek, Ltd., developer of vascular grafts; and
Terumo Heart, developer of a ventricular assist device. Terumo Corporation is
a premier global medical company with 2003 annual sales in excess of $1.9
billion. Terumo Corporation develops, manufactures, and markets a wide range
of medical products including syringes, needles, catheters, and blood bags.
For more information, visit http://www.terumo-cvs.com .
SOURCE Terumo Cardiovascular Systems