Postperfusion syndrome

Postperfusion syndrome, also known as "pumphead", is a constellation of neurocognitive impairments attributed to cardiopulmonary bypass (CPB) during cardiac surgery. Symptoms of postperfusion syndrome are subtle and include defects associated with attention, concentration, short term memory, fine motor function, and speed of mental and motor responses.[1] Studies have shown a high incidence of neurocognitive deficit soon after surgery, but the deficits are often transient with no permanent neurological impairment.[1][2]

Evidence

A study by Newman et al. at Duke University Medical Center published in the New England Journal of Medicine (NEJM) showed an increased incidence of cognitive decline after coronary artery bypass surgery (CABG), both immediately (53 percent at discharge from hospital) and over time (36 percent six weeks, 24 percent at six months, and 42 percent at five years).[3] This study shows an association of neurocognitive decline with CABG, but does not show causation; the study lacks a control group and is considered level II-3 evidence. Also, the statistical calculation of cognitive decline has been demonstrated as the least reliable due to practice effects, measurement error and the regression to the mean phenomenon.[4]

Subsequent studies have compared "on-pump" CABG to off-pump coronary artery bypass (OPCAB)—essentially establishing controls to compare the incidence of neurocognitive decline in CABG with and without the use of CPB. A small study (60 patients total, 30 in each treatment arm) by Zamvar et al. demonstrated neurocognitive impairment was worse for the on-pump group both 1 week and 10 weeks postoperatively.[5] A larger study (281 patients total) by Van Dijk et al. showed CABG surgery without cardiopulmonary bypass improved cognitive outcomes 3 months after the procedure, but the effects were limited and became negligible at 12 months.[2] Furthermore, the Van Dijk study showed no difference between the on-pump and off-pump groups in quality of life, stroke rate, or all-cause mortality at 3 and 12 months. A study by Jenson et al. published in Circulation found no significant difference in the incidence of cognitive dysfunction 3 months after either OPCAB or conventional on-pump CABG.[1]

Given the above studies, there is high incidence of neurocognitive deficit shortly after bypass surgery, but evidence is less clear about long-term neurological impairment. Controlled "on-pump" versus "off-pump" cardiac surgery has only been studied in the setting of CABG and is not necessarily generalizable to other types of cardiac surgery. Recent advancements in transcatheter and percutaneous valve replacement may soon allow comparison of other types of cardiac surgery with and without CPB.

Neurocognitive deficit as a consequence of vascular disease

A study by McKhann et al.[6] compared the neurocognitive outcome of people with coronary artery disease (CAD) to heart-healthy controls (people with no cardiac risk factors). People with CAD were subdivided into treatment with CABG, OPCAB and non-surgical medical management. The three groups with CAD all performed significantly lower at baseline than the heart-healthy controls. All groups improved by 3 months, and there were minimal intrasubject changes from 3 to 12 months. No consistent difference between the CABG and off-pump patients was observed. The authors concluded patients with long-standing coronary artery disease have some degree of cognitive dysfunction secondary to cerebrovascular disease before surgery; there is no evidence the cognitive test performance of bypass surgery patients differed from similar control groups with coronary artery disease over a 12-month follow-up period. A related study by Selnes et al.[7] concluded patients with coronary artery bypass grafting did not differ from a comparable nonsurgical control group with coronary artery disease 1 or 3 years after baseline examination. This finding suggests that late cognitive decline after coronary artery bypass grafting previously reported by Newman et al.[3] may not be specific to the use of cardiopulmonary bypass, but may also occur in patients with very similar risk factors for cardiovascular and cerebrovascular disease.

Proposed mechanism

Physicians have theorized that the syndrome is caused by tiny debris and air bubbles (microemboli) that enter the brain via cardiopulmonary bypass. Surgeons attempt to minimize time spent on bypass to decrease postoperative deficits; studies have shown increased bypass time is associated with increased incidence and severity of postperfusion syndrome and mortality. It is unclear how increases in bypass time would result in such increases if pre-existing cardiovascular and cerebrovascular conditions are the principal causative mechanisms of postperfusion syndrome.

See also

References

  1. ^ a b c Jensen B, Hughes P, Rasmussen L, Pedersen P, Steinbrüchel D (2006). "Cognitive outcomes in elderly high-risk patients after off-pump versus conventional coronary artery bypass grafting: a randomized trial". Circulation. 113 (24): 2790–5. doi:10.1161/CIRCULATIONAHA.105.587931. PMID 16769915.
  2. ^ a b Van Dijk D, Jansen E, Hijman R, Nierich A, Diephuis J, Moons K, Lahpor J, Borst C, Keizer A, Nathoe H, Grobbee D, De Jaegere P, Kalkman C (2002). "Cognitive outcome after off-pump and on-pump coronary artery bypass graft surgery: a randomized trial". JAMA. 287 (11): 1405–12. doi:10.1001/jama.287.11.1405. PMID 11903027.
  3. ^ a b Newman M, Kirchner J, Phillips-Bute B, Gaver V, Grocott H, Jones R, Mark D, Reves J, Blumenthal J (2001). "Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery". N Engl J Med. 344 (6): 395–402. doi:10.1056/NEJM200102083440601. PMID 11172175.
  4. ^ Raymond P, Hinton-Bayre A, Radel M, Ray M, Marsh N (2006). "Assessment of statistical change criteria used to define significant change in neuropsychological test performance following cardiac surgery". Eur J Cardiothorac Surg. 29 (1): 82–88. doi:10.1016/j.ejcts.2005.10.016. PMID 16337395.
  5. ^ Zamvar V, Williams D, Hall J, Payne N, Cann C, Young K, Karthikeyan S, Dunne J (2002). "Assessment of neurocognitive impairment after off-pump and on-pump techniques for coronary artery bypass graft surgery: prospective randomised controlled trial". BMJ. 325 (7375): 1268. doi:10.1136/bmj.325.7375.1268. PMC 136922. PMID 12458242.
  6. ^ McKhann G, Grega M, Borowicz L, Bailey M, Barry S, Zeger S, Baumgartner W, Selnes O (2005). "Is there cognitive decline 1 year after CABG? Comparison with surgical and nonsurgical controls". Neurology. 65 (7): 991–9. doi:10.1212/01.wnl.0000175220.78475.99. PMID 16107605.
  7. ^ Selnes O, Grega M, Borowicz L, Barry S, Zeger S, Baumgartner W, McKhann G (2005). "Cognitive outcomes three years after coronary artery bypass surgery: a comparison of on-pump coronary artery bypass graft surgery and nonsurgical controls". Ann Thorac Surg. 79 (4): 1201–9. doi:10.1016/j.athoracsur.2004.10.011. PMID 15797050.

Further reading

External links

Cardiac surgery

Cardiac surgery, or cardiovascular surgery, is surgery on the heart or great vessels performed by cardiac surgeons. It is often used to treat complications of ischemic heart disease (for example, with coronary artery bypass grafting); to correct congenital heart disease; or to treat valvular heart disease from various causes, including endocarditis, rheumatic heart disease, and atherosclerosis. It also includes heart transplantation.

Cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the patient's body. The CPB pump itself is often referred to as a heart–lung machine or "the pump". Cardiopulmonary bypass pumps are operated by perfusionists. CPB is a form of extracorporeal circulation. Extracorporeal membrane oxygenation is generally used for longer-term treatment.

Cardiothoracic surgery

Cardiothoracic surgery (also known as thoracic surgery) is the field of medicine involved in surgical treatment of organs inside the thorax (the chest)—generally treatment of conditions of the heart (heart disease) and lungs (lung disease). In most countries, cardiac surgery (involving the heart and the great vessels) and general thoracic surgery (involving the lungs, esophagus, thymus, etc.) are separate surgical specialties; the exceptions are the United States, Australia, New Zealand, and some EU countries, such as the United Kingdom and Portugal.

Coronary artery bypass surgery

Coronary artery bypass surgery, also known as coronary artery bypass graft (CABG, pronounced "cabbage") surgery, and colloquially heart bypass or bypass surgery, is a surgical procedure to restore normal blood flow to an obstructed coronary artery. A normal coronary artery transports blood to and from the heart muscle itself, not through the main circulatory system.

There are two main approaches. In one, the left internal thoracic artery, LITA (also called left internal mammary artery, LIMA) is diverted to the left anterior descending branch of the left coronary artery. In this method, the artery is "pedicled" which means it is not detached from the origin. In the other, a great saphenous vein is removed from a leg; one end is attached to the aorta or one of its major branches, and the other end is attached to the obstructed artery immediately after the obstruction to restore blood flow.

CABG is performed to relieve angina unsatisfactorily controlled by maximum tolerated anti-ischemic medication, prevent or relieve left ventricular dysfunction, and/or reduce the risk of death. CABG does not prevent myocardial infarction (heart attack). This surgery is usually performed with the heart stopped, necessitating the usage of cardiopulmonary bypass. However, two alternative techniques are also available, allowing CABG to be performed on a beating heart either without using the cardiopulmonary bypass, a procedure referred to as "off-pump" surgery, or performing beating surgery using partial assistance of the cardiopulmonary bypass, a procedure referred to as "on-pump beating" surgery. The latter procedure offers the advantages of the on-pump stopped and off-pump while minimizing their respective side-effects.

CABG is often indicated when coronary arteries have a 50 to 99 percent obstruction. The obstruction being bypassed is typically due to arteriosclerosis, atherosclerosis, or both. Arteriosclerosis is characterized by thickening, loss of elasticity, and calcification of the arterial wall, most often resulting in a generalized narrowing in the affected coronary artery. Atherosclerosis is characterized by yellowish plaques of cholesterol, lipids, and cellular debris deposited into the inner layer of the wall of a large or medium-sized coronary artery, most often resulting in a partial obstruction in the affected artery. Either condition can limit blood flow if it causes a cross-sectional narrowing of at least 50 percent.

List of syndromes

This is an alphabetically-sorted list of medical syndromes.

Off-pump coronary artery bypass

Off-pump coronary artery bypass or "beating heart" surgery is a form of coronary artery bypass graft (CABG) surgery performed without cardiopulmonary bypass (heart-lung machine) as a treatment for coronary heart disease. It was primarily developed in the early 1990s by Dr. Amano Atsushi. During most bypass surgeries, the heart is stopped and a heart-lung machine takes over the work of the heart and lungs. When a cardiac surgeon chooses to perform the CABG procedure off-pump, also known as OPCAB (Off-pump Coronary Artery Bypass), the heart is still beating while the graft attachments are made to bypass a blockage.

Off-pump coronary artery bypass was developed partly to avoid the complications of cardiopulmonary bypass during cardiac surgery. The medical community believes cardiopulmonary bypass causes a post-operative cognitive decline known as postperfusion syndrome (informally called "pumphead"), but research has shown no long-term difference between on and off pump coronary artery bypass in patients of lower risk. This is probably because the pump is not the main cause of brain damage at all, rather it is the embolic process described below.

Sometimes the fatty type materials that collects to form a blockage or lining on the walls of the artery may break loose during CABG procedure manipulation. This debris can result in clots, or “emboli”, that may interrupt the flow of blood to the brain, causing neurological damage or even stroke. Data analysis from beating heart surgery patients shows a significant reduction in the release of this debris with correspondingly lower stroke rates.

The fatty emboli which cause brain damage are generated when the large artery from the heart (aorta) is manipulated and although these are reduced in most off-pump coronary bypass surgeries they are not eliminated because the aorta is still used as a site to attach some of the grafts. A growing number of OPCAB surgeons, however, are avoiding the aorta completely, known as "anaortic" or no-touch coronary bypass surgery, by taking all their grafts from sites other than the aorta (e.g. the internal mammary arteries.). This results in a very low risk of stroke, actually less than occurs during percutaneous coronary intervention In addition to off-pump surgery being associated with the clinical benefits of a reduced risk of stroke or memory problems, patients also typically have a faster recovery and shorter hospital stay, fewer blood transfusions, and fewer unwanted inflammatory/immune response issues.

Off-pump surgery can be more technically challenging. The technique has a steep learning curve, but with adequate training and experience, the quality of the anastomoses has been shown to be similar to on-pump results in surgeons with comparable experience

On February 18, 2012 Amano Atsushi performed a successful off-pump coronary artery bypass operation on Emperor Akihito.

Vasoplegic syndrome

Vasoplegic syndrome (VPS) is a postperfusion syndrome characterized by low systemic vascular resistance and a high cardiac output.

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