New device gives heart failure patients more freedom
October 30, 2000
New device gives heart failure patients more freedom
October 30, 2000
At 1 p.m. on October 30,2000, Clifford Doyle, a 73-year-old former Chicago policeman who suffers from advanced heart failure, will become the first patient ever to be discharged from the hospital with new category of cardiac-assist device surgically implanted in his aorta. The device is designed to help his severely diseased and damaged heart pump blood while preserving his independence and freedom of movement.
The Kantrowitz CardioVad (TM) System is the only heart-assist device that can be turned on and off to reach human trials. Unlike other artificial hearts or left-ventricular-assist devices, it does not usurp the entire job of pumping blood. Instead, it boosts the patient's own heart, taking over up to 50 percent of the heart's function--but retaining all of the heart's pre-surgical pumping capacity.
As a result, the patient can release himself for a few minutes or even hours whenever he feels well enough, making it easier to take a shower or go out to dinner. It is also the only such device that doesn't require blood thinners to prevent clots.
"This is the first example of the second generation of cardiac assist devices," said Valluvan Jeevanandam, MD, section chief of cardio-thoracic surgery at the University of Chicago, who performed Doyle's operation. "Although the clinical trial is just beginning, we hope that this will be a far safer, more convenient, more accommodating way to support patients with congestive heart failure than the other mechanical options."
"For Mr. Doyle," he added, "it has already made a world of difference."
After evaluation and several meetings with Jeevanandam and cardiologist Allen Anderson, MD, director of the University's heart failure program, Doyle entered the University of Chicago Hospitals on October 4, 2000 for surgery the next day. Before his operation he was unable to walk 20 yards. He constantly felt exhausted, yet too uncomfortable to sleep well. He couldn't even shave without pausing to catch his breath. His heart failure was slowly damaging other organs including his kidney. Because of his age, advanced disease and multiple complications, he was not a candidate for a heart transplant.
The five-hour operation to implant the device went smoothly on October 5, 2000. Instead of splitting the breastbone, as in most open-heart procedures, the team, led by heart surgeons Jeevanandam and David Jayakar, entered between two ribs on the left side of Doyle's chest, sutured the pumping device into his aorta, and ran the wire that connects the internal pump to the external power source down to his abdomen, where they implanted an access port.
The next morning, Doyle was sitting up in a chair, talking and eating. His heart, which had been pumping only three liters of blood per minute before surgery, was now moving more than seven liters per minute. With a better blood supply, his kidney function steadily improved and is now back to normal.
Doyle frequently unhooks himself for trips to the bathroom or to walk the halls. He even went home briefly, on Friday and Sunday, with a "day pass" out of the hospital. "I was starting to get tired of hospital food," he explained.
The CardioVad (TM) System was developed by Adrian Kantrowitz, MD, of L.VAD Technology, based in Detroit, Michigan. The first U.S. surgeon to perform a heart transplant, Kantrowitz has been working on this project for more than 30 years. One of his early spin-offs was a temporary assist device, the intra-aortic balloon pump, which is now used 100,000 times a year worldwide to support patients in acute heart failure.
Creating a permanent balloon pump has been much more challenging, however. It required developing complex computer technology that allows the pump to match the heart's natural rhythms, speeding up or slowing down as needed. The pumping bladder, the only internal moving part in this device, has to withstand the wear and tear of inflating and deflating 60 to 100 times a minute, all day, everyday, up to 50 million times a year for 10 years or more, without lubrication or maintenance. The internal parts must all be biocompatible, able to resist infection, which hampered earlier trials, and must not cause the blood to clot.
"It took of 30 years of tinkering and testing," said Kantrowitz, "making, discovering and fixing our mistakes, before we got this thing right and decided we were finally ready to begin careful clinical trials."
The device has three main parts. The pumping bladder, six inches long and three-quarters of an inch wide and weighing less than one ounce, is sewed into the aorta, the large main vessel coming out of the heart. When the heart relaxes between beats, the bladder expands, pushing blood through the aorta to the tissues and into the coronary arteries that supply the heart. When the heart contracts, the bladder deflates, drawing blood from the left ventricle and reducing the heart's workload.
The access device consists of two small tubes that lead from the pumping bladder within the aorta to a port on the skin. One tube relays information about the heart's timing and electrical activity to an attached computer. The other tube allows the external drive to pump air in and out to inflate and deflate the bladder. To reduce the risk of infections, the access device is pre-coated with a thin layer of cells derived from the patient's skin and grown in the laboratory for about a week.
The external drive unit controls pump timing and powers the bladder. Patients receive two interchangeable drivers. One is a five-pound battery-powered unit that can be worn in a vest or backpack. The rechargeable batteries last about two hours. The other is a small-suitcase-sized unit on wheels that can be plugged into household current.
Heart failure, the inability of the heart to keep up with its workload of pumping blood to the lungs and the rest of the body, has become increasingly common as the baby boom generation enters old age. An estimated 4.8 million people, twice as many as 10 years ago, have congestive heart failure, which can usually be controlled with medication. More than 400,000 new cases are diagnosed each year.
About 40,000 people currently suffer from end-stage heart failure. Many of these patients are candidates for transplant, but fewer than 2,500 hearts become available each year. The CardioVad (TM) System was designed for patients with chronic congestive heart failure who have frequent hospitalization and poor quality of life but are not transplant candidates.
For Doyle heart failure resulted from a massive heart attack that occurred after he mowed the lawns of six neighbors on May 11, 1999. He never regained adequate heart function after his initial injury, and the gradual damage to other organs, caused by poor blood supply, was beginning to accumulate.
Doyle admitted to being "very apprehensive--very, very apprehensive" the evening before his surgery but is now eager to regain strength and return to his home on the South Side of Chicago. His three children and five grandchildren have visited regularly in the hospital.
As a lifelong music lover, he is particularly interested in following the burgeoning career of his grandchild Conley Johnson, Jr., a keyboard prodigy, who performed with the Chicago Symphony at the age of 14 and this fall entered Peabody Conservatory on a full scholarship to study piano performance.
"I am waiting for him to perform a solo recital at Carnegie Hall," said Doyle, "and I intend to be there."