Reversing or Avoiding Acidosis in Heart Tissue During Cardiac Surgery Improves Long-Term Patient Survival

Study underscores value of monitoring intraoperative myocardial pH

Mar 01, 2005, 00:00 ET from Terumo Cardiovascular Systems

    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 .
     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 .

SOURCE Terumo Cardiovascular Systems