Surgery for swinging-door heart valves has issues
Mitral valve surgery can best be described by comparison to the swinging saloon door in old western movies as it demonstrates what can go wrong with the heart’s valves and what surgical procedure is needed to correct mitral valve prolapse (MVP).
To get a first-hand view of this procedure, I watched Dr. Tirone David, one the world’s great cardiac surgeons, perform the operation at Toronto General Hospital.
The mitral valve separates the two left chambers of the heart. Each time the heart beats the valves swing open, like the doors of a western saloon. But after opening they close firmly again while the heart pumps blood to the body.
The problem is that swinging doors of saloons often develop loose rusty hinges that don’t close well. The mitral valve has the same trouble when the tough parachute-like cords that attach the valves to the heart’s muscle become too loose. When this happens some ejected blood falls back into the heart’s chamber following every beat. This places extra burden on the heart’s muscle.
If you’re diagnosed with this condition, don’t panic. You’re far from the end of the road. Prior to the use of echocardiograms (ultrasound of the heart), doctors believed MVP was present in 17 per cent of women and five per cent of men. Now we know it’s less common, affecting about 2.4 per cent of both sexes. But, according to a report from Johns Hopkins University, about 25 per cent of Americans older than age 55 have some degree of MVP. It’s now believed that, in addition to aging, genetics also plays a role in who develops this condition.
How mitral valve prolapse is treated depends on several factors. The great majority of patients with MVP have no idea it is present and normally do not need surgery.
Some patients complain of shortness of breath, palpitations and fatigue. But people without MVP can experience similar symptoms. What often happens is these symptoms occur after the diagnosis, triggering anxiety.
David says that several factors must be considered before deciding mitral surgery is needed. One of the most important is the severity of the prolapse and what affect it’s having on the heart’s muscle.
There’s an old saying that, “A stitch in time saves nine”. In mild cases of MVP, there’s no point in exposing patients prematurely to the risk of surgery. But it also makes no sense to wait until either the patient’s symptoms are severe or the muscles of the heart are failing from extra stress.
Mitral valve surgery is not just for incompetent valves. It’s also performed when the mitral valve becomes thickened and rigid from aging and the opening becomes as small as a pencil. The extra work of pushing blood through such a tiny opening can also cause heart failure.
Patients with these conditions often have heart murmurs that can be detected by a stethoscope. But an echocardiogram of the heart will determine their severity and help to gauge whether the condition is worsening.
In recent years there’s been tremendous advancements in surgical technique for the treatment of MVP or stenosis.
The morning I watched David operate, the patient’s chest was opened in the same way as a bypass operation. This patient suffered from severe mitral stenosis and required a totally new valve.
The majority of cases performed today try to save the old valve. For instance, it is often possible to shorten the parachute-like cords which restore the valves to their normal position. The advantage to using the patient’s own tissue is that there is no chance of its rejection by the body.
In other cases, minimal invasive surgery can be done by working through the femoral artery, the blood vessel at the top of the leg. A new valve is guided through the artery using a special catheter tube until it reaches the mitral valve location and is inserted.
David says there’s no age limit for mitral valve surgery as long as the patient has no other problems that would increase the risk. His oldest mitral valve patient was 95 years of age.