Flow Measurement is Valuable in Both
While intraoperative flow measurement has become a standard quality tool in off-pump CABG, it is also valuable during on-pump CABG to predict the patency of the graft when the patient is taken off-pump. More in this in our On/Off-Pump Focus Note >
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On Pump Diagram |
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Observed benefits of OPCAB include: |
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Reduced
perioperative myocardial damage
lower rates
of renal dysfunction, artial fibrillation, stroke, sternal wound infection, and need for transfusion.
OPCAB has
also been associated with reduced postoperative ventilation time, shorter hospital stays, and lower costs.1
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A Short History of CABG Surgery
Dr. John H. Gibbons Jr. is credited with developing the first clinically successful heart-lung pump. He first used it on May 6th, 1953 as he closed a hole
between the upper heart chambers in an 18 year old girl. The machine was soon being used in cardiac artery bypass procedures and by the early 1960s,
coronary artery bypass graft (CABG) surgery had become fairly routine.
While the development of the heart-lung machine has saved countless thousands of lives, its use is
not without risk. These risks include an increased risk for stroke and cognitive decline, and kidney and lung complications. Looking to improve patient
outcomes, pioneering cardiac surgeons in South America began attempting bypass grafting on a beating heart in the early 1980s.
Since those early days, off-pump coronary artery bypass (OPCAB) has rapidly evolved with better devices for stabilizing the heart,
anesthetic techniques and improved surgeon experience. As the technique was refined, its proponents have ventured to compare it directly with traditional CABG.
Studies Add to Debate Over Which Procedure is Better
Khan et al published a study in the New England Journal of Medicine (Vol. 350:21-28, Jan. 1, 2004)
that elicited much attention and was frequently referenced by the popular press. Entitled “A Randomized Comparison of Off-Pump and On-pump Multivessel Coronary-Artery Bypass
Surgery,” the authors concluded that the graft patency rate was lower at three months in the off-pump group than in the on-pump group. This set off a
series of responses from surgeons who questioned both the validity of the study and the skills of the surgeons involved.
The paper raised so many issues that CTSNet’s Beating Heart Surgery Center site www.ctsnet.org started a
discussion group where interested parties could post their comments. One such posting included the statement that the “article in question, published by a major journal,
is inobservant of the principles set forth by the scientific community on the report of studies and investigations. This issue should be addressed.” Pretty strong stuff.
One study published in the New England Journal of Medicine in 2001 indicates that 40% of patients who undergo traditional
bypass surgery experience longterm cognitive deficits.2 Data from other studies suggest that some of these complications
may be avoided with beating heart bypass surgery.3
A study published in the April, 2004 issue of the Journal of the American Medical Association has contributed to
this ongoing debate over which procedure is best for doing bypass surgery. The study, conducted at Emory University School of Medicine in Atlanta, GA tried to address many
of the perceived weaknesses of former studies.
The paper, “Off-Pump vs Conventional Coronary Artery Bypass Grafting: Early and 1-Year Graft Patency, Cost and
Quality-of-Life Outcomes. A Randomized Trial,” was conducted by Dr. John D. Puskas, an early proponent of OPCAB. The aspects that made this study notable include that Dr.
Puskas randomized patients screened for the study, the examined a broader array of inhospital and 1-year outcomes and had a high percentage of patient followup. Plus, a
single surgeon performed all of the procedures and that surgeon was very experienced in OPCAB procedures.
The study took place over the course of 18 months and included 200 patients—3 of whom were later withdrawn for
mitral valve repair or replacement. Followup was done at 30 days after surgery and one year. The study concluded that graft patency was similar for OPCAB and conventional
CABG at 30 days and 1 year. Rates of death, stroke, myocardial infarction, angina and reintervention were also similar. They found no significant differences in
health-related quality of life. The biggest difference found was the mean total hospitalization cost per patient. OPCAB was found to be $2272 cheaper than traditional CABG. Two doctors, in an
editorial in the same journal, commended Dr. Puskas’ efforts but said that only a large, multicenter randomized trial would address the important outstanding questions.
In the most recent study in the Annals of Thoracic Surgery (2005 Dec;80(6):2132-40), Frank Onorati et al concluded that "Off-pump coronary artery bypass grafting and cardiopulmonary bypass coronary artery bypass grafting demonstrated similar clinical, biochemical, and transit-time flowmetric results, as well as comparable graft flow reserve..." The data excludes "...a lower anastomotic quality in off-pump coronary artery bypass grafting. "4 View Abstract >
References
- Peterson, E., Off-Pump Bypass Surgery—Ready for the Big Dance? Journal of the American Medical Association,
2004; 291 (15): 1897-1899.
- Newman, D. Longitudinal Assessment of Neurocognitive Function after coronary artery bypass surgery. The New
England Journal of Medicine, 2001; 344: 395-402.
- Diegeler A et al. Neuromonitoring and neurocognitive outcome in off-pump versus conventional coronary bypass
operation. Annals of Thoracic Surgery, 2000 Apr, 69(4):1162-6
- Onorati F
, Olivito S, Mastroroberto P, di Virgilio A, Esposito A, Perrotti A, Renzulli A., Perioperative patency of coronary artery bypass grafting is not influenced by off-pump technique. Ann Thorac Surg.. 2005 Dec;80(6):2132-40
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