The rise in obesity buoys many trend lines. As a risk factor for a host of diseases, obesity contributes to upticks in hypertension, diabetes, heart failure and other conditions. Specialists and hospitals treating these patients face additional challenges that range from adapting interventional and imaging procedures to acquiring supersized equipment. Is there a way to turn the tide? Bariatric surgery offers one strategy.
Wave of the future
Body Mass Index* Classifications
*BMI=weight in kilograms divided by height in meters squared
Source: American Journal of Radiology 2007;188:433-440
Being obese or overweight ranks No. 5 on the World Health Organization’s list of leading risk factors for mortality, contributing to 8.4 percent of deaths in high-income countries. In 2010, one in three adults in the U.S. was obese, meaning they had a body mass index of 30 or greater, according the Centers for Disease Control and Prevention. Almost 17 percent of children and adolescents also met the criteria for obesity.
Among the trends pushing alarm bells is the prevalence of obesity in children between the ages of 6 and 11, which jumped from 4 percent to 11 percent in 30 years. On the other end of the age spectrum, obesity prevalence in Medicare beneficiaries rose 5.6 percent in a five-year span, prompting forecasts that by 2030 more than half the U.S. population will weigh in as obese (Circulation 2013;127:e6-e245). These people will not only pack on pounds but also mortality and morbidity risks.
A growing phenomenon that starts at an increasingly younger age, obesity portends generations of patients who may need treatment for cardiovascular risk factors such as hypertension, dyslipidemia and diabetes and also care for coronary heart disease, heart failure, stroke and other diseases predicted by obesity. “The increase in obesity has impacted us in a number of ways,” says Norma Keller, MD, chief of cardiology at Bellevue Hospital Center in New York City. “One is the (larger) number of patients with cardiovascular disease and the age at which we are seeing it. We see younger patients with more comorbidities like diabetes and high blood pressure.”
Complications extend beyond clinical challenges. To optimally treat certain obese patients, hospitals and their cardiovascular departments may need to invest in special equipment that can range from heavy-duty catheterization tables to scanners with larger aperture openings. And then there are issues related to basics such as toilets and beds.
A center of excellence for bariatric surgery, Bellevue purchased extra wide beds and bedding, motorized wheelchairs and stretchers to care for its morbidly obese patients. These specialty items carried hefty price tags, too. In 2012, a bariatric bed cost the hospital on average $22,500; a bariatric wheelchair $5,500 and an extra wide stretcher, $4,300. That may be as much as three times the cost of a standard hospital bed and twice the cost of a standard wheelchair, according to the New York City Health and Hospitals Corporation (HCC), an integrated healthcare delivery system that includes Bellevue.
HCC estimates that it spent millions of dollars in its hospitals on equipment, supplies and infrastructure to safely accommodate its obese patient population. That ranges from toilets that can support up to 500 pounds to operating tables with a capacity of 750 pounds.
If this is a tidal wave in the making, cardiology already has felt its first warning ripples. “In the medical world, the obesity epidemic has been obvious much longer than in the public because obese patients tend to be sicker,” says Udo Hoffmann, MD, a cardiac radiologist at Massachusetts General Hospital in Boston.
While bariatric centers have been designed with the obese in mind, some cardiac facilities may find they cannot accept some obese patients for safety reasons. “In the cath lab where (cardiologists) do diagnostic testing of the coronary arteries, weight can be an issue,” Keller says. Manufacturers for tables in catheterization laboratories, for instance, designate weight specifications and warn of potential dangers to patients and damage to equipment if the limit is exceeded.
In a survey to 94 institutions, Thomas E. Vanhecke, MD, of William Beaumont Hospital in Royal Oak, Mich., and colleagues asked cath lab nurse managers about their labs’ maximum weight limits, protocols when a patient exceeds that weight and an estimate of patients rejected as a consequence (Am J Cardiol 2008;102:285-286). Most labs reported having a limit of 450 pounds, but 10 went as low as 350 pounds and another 10 stopped at 400 pounds. Twenty-two percent said they referred patients to another facility for weight reasons. On average, hospitals rejected 5.2 patients per year because of weight issues.
Excessive weight can pose a variety of problems for interventional cardiologists. “Morbid obesity carries with it challenges for any interventional procedure, let alone an interventional cardiac procedure,” says Stephen Brecker, MD, consultant cardiologist at St. George’s Hospital in London. “For cardiac procedures using femoral (access), there are problems getting to the vessel, securing hemostasis and infections, but this is really in the grossly obese.”
Many cath lab operators prefer the femoral approach for angiography or PCI, but femoral vascular access may be difficult in patients with excessive adipose tissue. “One way to get around that is to use the radial artery, which is more superficial and has fewer complications in the obese patient,” Keller says.
One Canadian study that evaluated the safety and efficacy of a radial vs. femoral approach to coronary angiography in morbidly obese patients found that while the femoral approach was more common, at 64 percent of the 203 procedures, radial had a lower rate of bleeding complications and access site injuries (J Am Cardiol Intrv 2012;5:819-826). More recently, an observational study based on 2.8 million procedures in the National Cardiovascular Data Registry’s CathPCI Registry also gave the safety advantage to radial PCI in patients with a body mass index of 30 or greater. In that subgroup, the rate for bleeding complications was 2.17 percent vs. 5.06 percent for the femoral approach (Circulation 2013;127:2295-2306).
Both studies showed the radial approach had an increased fluoroscopy time, though, and 13 percent of sites in the CathPCI Registry did not perform radial access PCI.
|National Estimate of Obesity Prevalence & Cost|
|Millions of adult enrollees||Prevalence*||Obesity-attributed expenditures ($ millions)*|
|*2006 Medical Expenditure Panel Survey Source: Obesity 2012;20(1): 214-220|
Patient girth poses challenges to imagers as well, beginning with equipment that can accommodate a heavier weight and a larger body diameter. Typically, fluoroscopy equipment has been standardized for weights of 350 pounds or less with aperture diameter of 45 cm, although some bariatric imaging equipment can hold twice that weight limit with apertures of 60 cm. But at a cost: Coney Island Hospital, another member of HHC, paid $650,000 for a special radiographic and fluoroscopy unit to serve its obese patients.
Obtaining images of diagnostic quality also becomes challenging with obese patients, Hoffmann says. “If you have an obese patient, whatever you do in imaging, it is harder to penetrate the body and to get a signal that is sharp and precise.”
Beam penetration is compromised in radiography and sonography, for instance, because the x-rays and ultrasound energy are attenuated by fat tissue. How fat is distributed can influence image quality. With CT, there are concerns about increased noise, a limited field of view and image cropping. Magnetic resonance may require longer scanning times, which increases the possibility of motion and related artifacts. In nuclear medicine studies, dose often depends on weight, making radiation exposure an issue for obese patients.
“The cameras have difficulty because the diaphragm might be raised and excess fat and breast tissue, especially in obese women, can lead to artifacts on scans of the heart,” Keller says. “One way to deal with that is to use higher energy but that is (more) radiation.”
Another option is to bypass the fat entirely. “You can put a tube down someone’s throat like a scope and take a picture of the heart from the esophagus,” she suggests. Repositioning the patient, using different imaging techniques, injecting tracers to enhance the cardiac image or imaging for a longer time to maximize counts offer other possible solutions.
Fat of the matter
If obesity is the wave of the future then prevention is its breaker wall. Diet and exercise provide the preferred foundation, but for obese patients, losing weight and keeping it off through this strategy is often difficult to achieve and maintain. Bariatric surgery offers another approach for reducing cardiovascular risk factors, according to Philip Schauer, MD, director of the Cleveland Clinic’s Bariatric and Metabolic Institute.
But not all fat cells are the same.
“It is not just the weight itself,” says Schauer. “Excess body weight is stored differently by different phenotypes. It appears that truncal fat that increases waist circumference, that kind of fat is much more detrimental then subcutaneous fat.”
Schauer and colleagues designed a randomized trial to study the effects of two bariatric procedures on body fat and the function of beta-cells, which produce and release insulin, at one and two years (Diabetes Care, online Feb. 25). They randomized 60 moderately obese patients with uncontrolled type 2 diabetes to undergo intensive medical therapy plus Roux-en-Y gastric surgery, intensive medical therapy plus sleeve gastrectomy or intensive medical therapy alone. Both surgery approaches led to similar reductions in body fat. But gastric bypass had a greater reduction in truncal fat compared with sleeve gastrectomy; a 2.7-fold increase in insulin sensitivity from baseline, while the other approaches had none; and an almost six-fold increase in beta-cell function.
“The improvement in insulin sensitivity we think is purely a consequence of weight loss, which occurs over several months after surgery,” Schauer explains. The increase in insulin secretion may be due to a complex interplay between hormones that originate in the gastrointestinal tract and beta cells in the pancreas.
“Patients who have this surgery often have an immediate improvement in their blood sugar, even before they have lost any weight,” he says.
But there are risks. In another clinical trial that compared Roux-en-Y gastric surgery with medical therapy in a similar patient population, there were 50 percent more serious adverse events in the bypass group, including one anoxic brain injury, and 55 percent more nonserious adverse events (JAMA 2013; 309:2240-2249].
Just as in cardiac surgery, extreme weight makes a procedure more challenging and likely exacerbates complications. Schauer observes that the use of laparoscopic procedures alleviates some burden, but getting inside the abdomen and maneuvering around large organs can be arduous.
“The very large patient is not only technically challenging but he or she usually has more medical problems,” Schauer points out. The heavier the patient, the higher the risk for venous thromboembolism, for one. “He or she also has a much higher risk of having heart problems, particularly heart failure. In general, people who are obese are at slightly higher risk of infection. Many have diabetes and diabetes definitely is associated with a higher risk of infections.”
Keller sees benefits in early referral of some patients to bariatric surgery. Many of these patients are still relatively young. In a review by Schauer et al of 52 studies on bariatric surgery, the mean age was 42 years (Am J Cardiol 2011;108:1499-1507). “They have many years ahead of them that they can benefit from the comorbidity reduction, quality of life and reduced mortality,” Schauer says.
Keller also advocates outreach to the population who really could turn the tide in the obesity epidemic: kids. Bellevue staff visit schools and try to educate children about proper nutrition and exercise to reverse or prevent obesity from occurring.
“There is a positive impact of weight loss on heart function, diabetes, blood pressure, quality of life, every aspect of life—it can be done and it can be improved, even from a cardiovascular standpoint,” she emphasizes. “It is a message that is getting through.”