Off Pump Heart Surgery
Off pump heart surgery is a method of performing a coronary bypass operation for the purpose of treating advanced coronary heart disease while the heart is still beating normally.
Traditionally, coronary artery bypass procedures have been performed with the assistance of a heart lung machine also known as a cardiopulmonary bypass machine.
The heart lung machine takes over the work of the heart and lungs while the heart is stopped with cardioplegic solution. This allows the heart surgeon to perform delicate surgery on the surface of the heart with-out interference from movement and the presence of blood in the organ.
The majority of bypass operations are still performed 'on-pump'... using a bypass machine.
Off pump heart surgery techniques also known as beating heart bypass surgery are becoming increasingly accepted and utilized by cardiothoracic surgeons but still have some way to go before they are accepted 'without question' in the way that on-pump coronary artery bypass surgery is.
Cardiopulmonary bypass...where a heart lung machine is used to take over the blood oxygenation and circulation duties while the heart is stopped is associated with certain complications and risks to the patient. Although this surgical technique has been used pretty successfully for the last forty years it is not without its problems.
Think about it, you're having your sternum (breast bone) split down the middle, your chest opened up, your blood diverted through a machine and your heart stopped while little surgical incisions are made in your coronary arteries on the hearts surface and alternate pathways called grafts are sewn into 'healthy' portions of the coronary arteries...ultimately allowing an unimpeded blood supply to flow to your heart muscle. It's a very significant procedure...no two ways about it.
Of course, most of those surgical traumas listed above are common to both on-pump and off-pump procedures...sowhat are the specific problems that have been associated with on pump procedures?
On-pump surgical complications can occur in patients with associated disease conditions such asprior history of strokepoor left ventricular function (heart pumping action)carotid artery stenosis (neck arteries)heavy aortic calcification (main body artery)compromised pulmonary(lung)functionpoor renal(kidney)function
There is also ongoing concern about post-operative cognitive decline (thought and mental capacity) as a result of being connected to a heart lung machine for several hours. This is known as post-perfusion syndrome and is thought to occur due to very small emboli forming in the blood after it passes through the heart-lung machine and back into the body...causing brain injury.
This issue is somewhat controversial, with some studies seeming to point to legitimate concerns in this area while others find a lack of compelling evidence.
Cognitive Function after Bypass Surgery
Incidence of Cognitive Dysfunction after Bypass Surgery
Off pump bypass seeks to improve the process of recovering from heart bypass surgery while ensuring long-term success of graft viability... a high quality of revascularization.
It aims to directly address morbidity's (potential disease conditions) associated with coronary artery bypass surgery including stroke, renal failure and post operative bleeding requiring blood transfusion. However, one of its draw backs is in reliably performing high quality graft attachment ( anastamosis)on a beating heart and getting clear unhindered access to all surfaces of the heart that may require surgical intervention.
Surgeons who are used to performing off pump surgical techniques have developed a high degree of skill in this area and successful revascularization results seem to be comparable to that of working on a still heart during an on pump procedure.
However, bearing in mind the technical difficulties of beating heart bypass techniques, Off-pump heart surgery has been shown in some scientific studies to reduce rates of...encephalopathy (brain disorder)post operative dialysis requirementspost operative sternal wound infection (SWI)red blood cell transfusions (PRBC)
Additionally, important operative and peri-operative criteria such as those listed below appear to be more favorable with off-pump surgery...although as you can see, on-pump surgery has a very low complication rate also.The statistics below show data as reported by the Cleveland Clinic in the USA and should be viewed as representative of their particular experience in evaluating the effectiveness of off pump heart surgery
Death Rateson pump less than 1%off pump less than 0.5%
Operative and Peri-operative Strokeon pump less than 1.5%off pump less than 1%
Operative and Peri-operative MI (heart attack)on pump less than 1.5%off pump less than 1%
In 2004 the American Heart Association (AHA) published their guidelines in their journal Circulation to help illuminate the choice of whether to employ an on-pump or off-pump technique.
1. "For low-risk patients, Cardio-pulmonary Bypass (CPB) is safe; measurable morbidity is not common; and randomized trials show small, if any, differences in procedure-related outcomes. CPB provides optimal exposure and an optimal surgical field, and, when complex revascularization is desirable, particularly using multiple Internal Thoracic Artery (ITA) grafts, these operations are carried out efficiently using CPB"
2. "Patients with severe ascending aortic and/or arch atherosclerosis or previous stroke are a group at increased risk during the use of CPB and may often benefit from off-pump surgery and, in particular, an off-pump surgery approach that minimizes aortic manipulation"
3. "Elderly patients appear to experience a more rapid recovery and may have a lower stroke rate when off-pump surgery is used"
On-Pump and Off-Pump Bypass Surgery: Tools for Revascularization Bruce W. Lytle and Joseph F. Sabik
Off pump heart surgery is certainly an evolutionary step forwards in improved surgical technique that seems to offer some advantages in some patient groups but not necessarily for everybody.
If you're a patient facing coronary bypass surgery and Off pump heart surgery is available in your area then talk to your Cardiologist about the pro's and cons to help get the best possible outcome for you.
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