Overview
The Process
According to the American Heart Association, a coronary bypass involves grafting blood vessels onto the heart to reroute blocked coronary arteries, restoring normal blood flow to the heart. Unfortunately, however, this normally life-saving procedure makes the patient vulnerable to acute renal (kidney) failure, a potentially deadly complication. The percentage of patients who develop this complication seems to grow every year. A 2006 article on Medical News Today quoted a study from Duke University Medical Center showing that the rate of acute renal failure among bypass patients skyrocketed from 1.5 percent in 1988 to 7.2 percent in 2003.
Acute renal failure occurs despite bypass surgeons' best efforts to prevent damage to the kidneys, including maintaining correct hydration during surgery and matching medication levels to kidney function levels after surgery. Researchers have promoted certain theories to explain this side effect, including speculation involving the heart-lung machines used, blood clots, drugs used during the bypass and genetics.
Genetic and Health-related Causes
Researchers have found some indications that a gene mutation called T-786C endothelial nitric oxide synthase (eNos) polymorphism may increase the likelihood of acute renal failure. Molecular Diagnostics Laboratories describes eNOS as a gene that helps the body make nitric acid to help maintain blood vessels. The T-786C mutation blocks this process, making the body more prone to heart muscle spams and heart attacks. A study published by the European Journal of Cardio-Thoracic Surgery found that the same mutation may also cause renal problems.
Fatty deposits in arteries may lead to renal complications. Medical News Today mentions the possibility that bypass surgery may cause bits of built-up cholesterol to break away from artery walls and end up as blockages in the kidneys' blood vessels. The Mayo Clinic confirms that this sequence of events, which also occurs naturally from hardening of the arteries, causes acute renal failure.
Surgical Procedures as Causes
The Medical News Today article, "Incidence of Kidney Damage After Heart Surgery on the Rise," includes the use of a heart-lung machine during coronary bypass surgery as a possible reason for the incidence of acute renal failure. According to Cincinnati Children's Heart Institute, heart-lung machines can indeed inflict damage on kidneys during a bypass surgery, causing a range of problems from urinary impairment to outright kidney failure.
The same article on Medical News Today states that bypass surgery drugs may cause clotting during the bypass. NowPublic.com posted a 2007 press release confirming that the Food and Drug Administration (FDA) had requested the removal of one such drug from the market. Traysol, a medication used to limit bleeding during heart operations, led to an increased risk of kidney damage, according to the press release.
Tags: renal failure, acute renal, bypass surgery, Medical News, Medical News Today, News Today