This is Sarah Long. And this is Steve Ember with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today we tell about a patient who received a new kind of mechanical heart. And we tell about a device implanted in Vice President Dick Cheney to make his heart beat normally.
Earlier this month, American doctors placed a mechanical heart in the chest of a patient dying of heart disease. The new device has no wires or tubes connected to equipment outside the body. It was the first such implant ever placed in a human.
The mechanical heart is called an AbioCor. It contains a pump that forces blood through the device to replace normal heart action. Abiomed Incorporated of Danvers, Massachusetts developed the mechanical heart. It is made of titanium and plastic. It weighs less than one kilogram.
Laman Gray and Robert Dowling placed the AbioCor in the patient at Jewish Hospital in Louisville, Kentucky. The operation took seven hours. Its goal was to permit the patient to live a month or two longer.
Hospital officials identified the patient only as a man in his fifties. He had suffered several damaging heart attacks. Examinations showed he had only days or weeks to live. He also had diabetes and kidney failure. This prevented him from receiving a human heart.
During the operation, Doctor Gray and Doctor Dowling removed most of the man's diseased heart. Then they connected the AbioCor to the two upper parts of the remaining heart, the left and right atria. The doctors connected the mechanical heart to the aorta, the main artery to the body. They also connected the device to the pulmonary artery, which carries blood to the lungs.
Unlike a human heart, the rhythm of the AbioCor depends on the level of blood pressure in the arteries. The human heart pumps blood to the body and lungs at the same time. The AbioCor works differently. It pumps blood to the body. Then it pumps blood to the lungs. Then it pumps blood to the body again.
The AbioCor receives power from a battery worn on the body. The patient wears this battery pack around the waist, like a belt. It sends power across the skin to another battery inside the abdomen.
Doctor Gray noted that the patient's body does not reject the mechanical heart because it does not contain foreign tissue.
Space engineers helped develop the AbioCor. They designed it to prevent blockages in blood vessels that cause strokes. They also designed it to prevent infections. These conditions harmed patients who received earlier mechanical hearts.
The earlier devices depended on tubes from the patient to machines outside the body. Infections developed because the patient always had an open wound. And the patient could not move around without also moving the equipment.
The federal government approved the AbioCor earlier this year for experimental use. Its developers say the goal of the device is to give severely sick patients another one to five years of life. But Abiomed officials also said they would consider their invention successful if the patient in Kentucky survived for sixty days. This is because his condition was so poor before receiving the device. Doctors also want to learn if the implant causes pain or robs the patient of any mental abilities.
Several other patients with severe heart disease also may receive the mechanical hearts. Four other hospitals in the United States have been chosen to perform AbioCor implant operations.
Experts not involved in the AbioCor implant disagreed about its value. Some doctors praised the AbioCor as a major development in treatment of heart disease. They said the mechanical heart could keep patients alive while they wait to receive a human heart.
Other experts said better tools than the AbioCor are currently in use. For example, some patients with severe heart disease receive ventricular assist devices. Doctors implant this device in the patient's chest without removing the heart. It helps the heart work better. Doctors have used ventricular assist devices for ten years.
The first permanent mechanical heart was placed in a human patient in the United States in Nineteen-Eighty-Two. Robert Jarvik invented this device, the Jarvik-Seven. It was implanted in the chest of a man named Barney Clark. The Jarvik-Seven had tubes from the patient to large equipment outside his body. Mr. Clark lived one-hundred-twelve days after the operation. During that time he suffered kidney failure and other severe problems.
You are listening to the Special English program SCIENCE IN THE NEWS on VOA. This is Sarah Long with Steve Ember in Washington.
Doctors in Washington, D.C. recently placed a special heart device in the chest of Vice President Dick Cheney. The goal was to help his heart beat normally. Mr. Cheney had the operation at George Washington University Hospital. Doctors performed the operation to prevent trouble with the rhythm of his heart.
Mr. Cheney is sixty years old. He has suffered four heart attacks in the last twenty-three years. This was the third operation to treat a heart problem since he was elected vice president in November.
The vice president received a device called an implantable cardioverter defibrillator or I-C-D. The electrical device has two purposes. One is to keep the heart beating at a normal rate. The other is to prevent the heart from fibrillating. Fibrillation is a dangerous process in which the heart beats wildly out of control. So the device is both a pacemaker and defibrillator. A pacemaker speeds up a heart that is beating too slowly. A defibrillator prevents death from a wildly beating heart.
Doctors placed the small I-C-D in Mr. Cheney's body through a cut in the chest below the shoulder. The I-C-D records heart activity through wires called leads. These leads are passed through veins into the heart. There they act like a computer as they document heart action.
An I-C-D speeds a patient's heartbeat if it falls below forty beats each minute. The device also slows the heartbeat if it becomes faster than one-hundred beats a minute. And the I-C-D sends more electricity if the heart starts beating out of control. This additional electricity can stop abnormally wild, fast heartbeats before they become deadly.
When the device detects harmful rhythms, it sends a shock of electricity through the leads to correct the rhythms. Sometimes the patient does not feel this. Other times it can feel like being hit in the chest.
Almost sixty-eight-thousand people around the world received I-C-D devices last year. The vice president decided to have the I-C-D after being examined by a heart monitor. This device records the electrical performance of the heart. Mr. Cheney wore it for thirty-four hours. His doctor observed that Mr. Cheney's heart beat abnormally fast four times during the test.
This abnormal activity is called ventricular tachycardia. It happens when the main pumping part of the heart beats too quickly. Mr. Cheney then had another test called an electrophysiology study. This test confirmed his need for the I-C-D.
The vice president returned to work less than forty-eight hours after receiving his I-C-D.
Dick Cheney had his first heart attack at age thirty-seven. He suffered his most recent heart attack last November. Doctors told him that that one artery was almost completely blocked. They placed a small metal tube device inside the artery to keep it open. This device is called a stent.
Mr. Cheney went to the hospital again after suffering chest pains in March. The doctors found a one-millimeter area of narrowing at one end of the stent. The doctors opened the blocked area using a method called balloon angioplasty.
Vice President Cheney's heart trouble has caused some observers to question whether he can finish his term in office. But his doctors and other experts say Mr. Cheney should be well enough to carry out his duties as vice president.
This SCIENCE IN THE NEWS program was written by Jerilyn Watson. It was produced by Caty Weaver. This is Sarah Long. And this is Steve Ember. Join us again next week for more news about science in Special English on the Voice of America.