PICTURE A RED BLOOD CELL TRAVeling through the venous system toward the heart. It enters the heart through one of two major veins, either the superior vena cava or the inferior vena cava, and passes into the right atrium. The one-way tricuspid valve opens, and the cell flows into the right ventricle. The tri-cuspid valve is composed of three leaflets that are connected on their underside (right ventricle side) to string-like structures called chordae tendineae, which are connected to muscles called papillary muscles. The papillary muscles are outgrowths of the muscular right ventricular wall.
As the right ventricle contracts, the tricuspid valve closes and the pulmonary valve opens, allowing the blood cell to be pumped, or propelled, into the pulmonary artery, which channels unoxygenated blood containing carbon dioxide to the lungs. Like the tricuspid, the pulmonary valve is one-way and composed of three leaflets (also called cusps), although the leaflets differ from those of the tricuspid valve in shape. They look like three small cups. The pulmonary valve does not have chordae tendineae or papillary muscles.
After giving off carbon dioxide and picking up oxygen in the lungs, the newly oxygenated red blood cell returns to the heart through one of the pulmonary veins and into the left atrium. The two-leaflet mitral valve opens, and the cell travels into the left ventricle. Like the tricuspid, the mitral valve has chordae tendineae, which are attached to papillary muscles. When the mitral and tricuspid valves are closed, the valve leaflets look like a parachute, and the chordae tendineae resemble the cords that connect the parachute to the jumper. The papillary muscle is the jumper.
When the left ventricle contracts, the aortic valve opens, allowing the red blood cell to stream out the aorta and into the arterial system that nourishes the body (see Fig. 10.1 for cardiac cycle). The two coronary arteries branch off the base of the aorta (aortic root) just above the aortic valve leaflets.
Before the Heart-Lung Machine:
The first attempt to open a stenotic (narrowed) heart valve in a human was carried out by Dr. Theodore Tuffier, a French surgeon, on July 13, 1912. After opening the patient's chest, he supposedly pushed the wall of the aorta near the heart through the stenotic aortic valve
String-like attachments that are part of the mitral and tricuspid valve apparatus that connects the valve leaflets, or flaps, to the papillary muscles on the ventricular wall.
Tiny muscles located in the left and right ventricles that are attached by chordae tendineae to the mitral and tricuspid valves. These muscle structures help control the valve function.
An abnormal narrowing of an orifice, blood vessel, or heart valve.
Dr. Elliot Cutler (below) performed the first successful mitral valve dilatation. His patient, a 12-year-old girl (right), had suffered from rheumatic fever. Her surgery was successful.
and dilated the valve. The patient survived and was reported to be improved.
About ten years later, Dr. Elliot Cutler, a surgeon at Harvard Medical School, in collaboration with Boston cardiologist Samuel Levine, worked out a procedure to dilate the mitral valve. Their first patient was a desperately ill twelve-year-old girl whose mitral valve had been badly damaged and narrowed from rheumatic fever. She underwent successful mitral valve dilatation on May 20, 1923. Unfortunately, most of Cutler's subsequent patients did not survive the surgery, and he abandoned the procedure.
These sporadic and mostly unsuccessful attempts ceased by 1929, and things remained quiet until 1945, when Dr. Charles Bailey and his team again attempted to treat mitral valve stenosis. The first of their five human patients was a thirty-seven-year-old man who was operated on on November 4, 1945. He bled to death in the operating room during the procedure. The second patient was a twenty-nine-year-old woman operated on on June 12, 1946. Her condition improved for the first thirty hours after the
surgery but suddenly deteriorated, and she died forty-eight hours after the surgery. After these two failures, Bailey's home base, Hahnemann Hospital in Philadelphia, refused to allow him to attempt any more mitral valve dilatations. He even became known as the "butcher" of Hahnemann Hospital.
Their third patient, who was treated at a different hospital, was a thirty-eight-year-old man operated on on March 22, 1948. The surgery seemed to go well, but the patient hemorrhaged into the chest cavity on the second postoperative day. He died of complications. Patient four was a thirty-two-year-old man who underwent heart surgery on June 10, 1948. His heart stopped while the incision was being made to start the surgery. He could not be resuscitated and died in the operating room.
The surgical team then immediately regrouped and rushed to Episcopal Hospital, where the fifth operation, this one on a young woman, was started before the bad news from that morning was known and the hospital administration could forbid the procedure. Her mitral valve dilatation was successfully completed. One week later, Bailey brought the patient by train one thousand miles to Chicago, where he presented her to the American College of Chest Physicians annual meeting. She was without symptoms after the surgery and felt better than she had been feeling for years.
On June 16, a few days after Bailey's success, Dr. Dwight Harken in Boston successfully performed his first mitral valve dilatation. Three months later, Sir Russell Brock in England did his first successful similar procedure but did not report it until 1950, when he described six additional successful attempts.
Targeting the Pulmonary Valve
On December 4, 1947, Dr. Thomas Holmes Sellers, an English surgeon, completed the first successful surgery on a
narrowed pulmonary valve. The surgery occurred during an operation for a congenital heart defect called tetralogy of Fallot. In this condition, there is an obstruction of blood to the lungs and a hole in the heart. This particular patient also suffered from advanced tuberculosis of both lungs. When Sellers opened the sac around the heart, he could feel the narrowed pulmonary heart valve each time the right ventricle contracted. He passed a special type of knife through the wall of the right ventricle and made slits in the narrowed valve. The patient made a good recovery and was markedly improved.
Like all forms of heart surgery, valvular surgery made great leaps forward as the heart-lung machine came into use. Doctors who had once only imagined the day when diseased valves could be replaced began to actually work to develop implantable valves. Artificial valves were not a novel idea. The first ones had been developed in the 1950s, when Drs. Charles Hufnagel in Washington, D.C., and J.M. Campbell in Oklahoma independently developed and implanted artificial valves in the descending aortas of dogs. This could be done before the heart-lung machine because the descending aorta is far enough away from the heart. The surgeon merely placed clamps several inches apart on the aorta to interrupt blood flow, opened the aorta, inserted the artificial valve, and then stitched the aorta closed.
These two valves, which were called "cage-ball valves" because of their design, looked similar. After presenting this mechanical heart valve technique in animals at the American College of Surgeons annual meeting in 1949, Hufnagel began to use this procedure in human patients suffering from aortic valve incompetence. The valve implantation did not actually replace the patient's own leaky aortic valve but acted as a supporting or auxiliary valve.
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