You gotta have heart. And indeed a healthy heart was once considered essential to human life. But today, medical technology has come so far in developing assistive devices designed to take over essential functions of faltering hearts that patients with diseased organs are living longer and better than ever before.
Heart disease remains a primary cause of death in Canada, the United States and much of the rest of the world. But since the mid-1980s, artificial-heart technology has been advancing by quantum leaps, and today hundreds of patients on the ever-lengthening waiting lists for heart transplants are going home to near-normal lives while they wait. These patients have a pump implanted inside the abdominal wall to provide circulatory support to the heart.
The ventricular assist device (VAD) takes over most of the workload of pumping blood through the heart, most often supporting the left ventricle, the heart's main pumping chamber. It takes in blood through a conduit connected to the heart and forces it back into the body's arterial system. The VAD is a self-regulating system that responds to the changing heartbeat and circulatory demands of the patient's activity level and is powered by an external battery pack, connected through the skin by a thin tube containing power wires.
"There have been several thousand implants of these devices in various countries around the world and the technology has proven itself to be very helpful in keeping the sickest patients in heart failure alive," says Dr. Paul Hendry, a cardiac surgeon and director of the circulatory and mechanical-devices section at the University of Ottawa Heart Institute.
Patients who have the portable devices can be quite mobile and resume most of their activities, Hendry says. "Some go back to work. One of our people is starting university. One is raising a family. So it's certainly much better than being in end-stage heart failure."
Among the several such devices available on the world market, a Canadian product, the Novacor Left Ventricle Assist System (LVAS), manufactured by the Ottawa-based World Heart corporation, is said to be known for durability and reliability. It's been implanted in approximately 1,300 patients in 90 centres worldwide. Of those patients, 95 have been supported on it for more than a year and two have surpassed the four-year milestone. Last month the North American record holder, Pete Kenyon, a 63-year-old Connecticut insurance salesman, received his heart transplant after more than three years supported by the device.
While the LVAS's primary purpose has been as a bridge to transplantation, it may soon provide an alternative for patients who are not candidates for a new organ and are dependent on intravenous medication.
The INTrEPID study (it stands for Investigation of Non-Transplant-Eligible Patients who are Inotrope [or intravenous drug] Dependent) has already begun in the U.S. and will be expanded to five or six Canadian centres to be identified over the coming weeks, says Hendry, who is the principal investigator for the Canadian trials.
"Those patients who are not transplant candidates but who would otherwise survive an operation, who are in bad heart failure, who are failing medical management and have to be on intravenous drugs to keep their heart function up are candidates for this study," he says. "We're going to be looking to see whether they would benefit from one of these devices … We expect that these people will live longer and feel better for whatever time they have."
It's good news on a number of fronts.
Hendry says the supply of donor hearts in Canada has plateaued and even decreased. "We are doing a couple hundred transplants a year across Canada and there's several thousand people who could benefit from a heart transplant if the hearts were there. It's in those patients we hope a mechanical option might be available."
And, despite the expense in manufacturing the complex assistive devices, there's definitely an economic benefit in getting chronic-heart patients out of hospital and cutting costs from health-care budgets, he adds.
But when Hendry said, "These things aren’t cheap," he wasn’t kidding." The cost of one LVAS is approximately $70,000 US, indicates the manufacturer World Heart. In Ontario, the provincial health plan covers the cost.
The best news for patients is in the improved quality of life, possibly for many years, for recipients of the devices. And that will only get better with the next generation of VADs.
The HeartSaver, developed at the Ottawa Heart Institute and also produced by World Heart, could be in human trials later this year. Similar to the LVAS, it's a smaller, completely internal device with implanted pump and back-up battery with no wires or cables perforating the skin. An electromagnetic energy-transfer system will allow communication through the skin between the pump and the external components.
Once approved for general use, Hendry says the HeartSaver will be available as an permanent alternative to transplant.