Lown Cardiovascular Research Foundation

Harvard Heart Letter | October 2008

Smaller surgery speeds recovery from valve fix
A less invasive operation to repair or replace a faulty valve rivals full, open-heart surgery.

There’s no simple remedy for a failing heart valve. It must be replaced or repaired. At least for now, this means surgery.

Traditional valve surgery requires splitting the breastbone from top to bottom, spreading the ribs, stopping the heart, and using a machine to circulate and oxygenate the blood. It is a very effective procedure and, when done by an experienced surgeon, is as safe as a major operation can be.

The big drawback is recovering from the operation. The wired-together breastbone and incision are painful, and may cause difficulty breathing, sleeping, and doing everyday activities. It can take several weeks for the breastbone to heal.

A smaller operation, developed in the late 1990s at the Cleveland Clinic and Harvard-affiliated Brigham and Women’s Hospital, offers the same excellent results as the traditional operation but with a smaller scar and faster recovery.

Valve failure

Each squeeze of the heart pumps blood in four directions. It’s an efficient piece of engineering made possible by four strategically placed valves. Each valve is made of tough but flexible flaps known as leaflets. They act like swinging doors that open and close with each heartbeat to create a one-way flow of blood through the heart and the body.

These valves, like the heart, are meant to last a lifetime. Sometimes, though, they don’t. Genes, infection, unhealthful habits, and plain old wear and tear can keep them from opening fully or closing tightly. Three main problems plague heart
valves:

Stenosis. An obstruction or narrowing that prevents the valve from opening fully is called stenosis. The smaller opening acts like a dam, holding back some blood in the chamber behind it.

Regurgitation. When a valve doesn’t close tightly, some of the blood just pumped out of a chamber can leak back into it. This backwash means less blood pumped forward with each beat.

Prolapse. A mismatch in the size, shape, or activity of valve leaflets can cause the closed valve to bulge (prolapse) in the direction of blood flow. In most people, this is a harmless state of affairs. In others, it progresses to regurgitation.

Stenosis and regurgitation make the heart work harder to supply the body’s tissues with the blood they need. They can cause symptoms such as shortness of breath, dizziness, fatigue, fluid accumulation in the legs or lungs, palpitations, and even chest pain. The heart often responds to the stress imposed by a faulty valve by growing larger or more muscular, which can further throw off the precise alignment of the valve. Left untreated, a malfunctioning valve can make life miserable, lead to heart failure, and shave years off life.

Although any valve can get into trouble, the aortic and mitral valves account for the majority of valve surgeries.

Shrinking surgery

The success of so-called keyhole surgery to remove an inflamed gallbladder in the early 1990s spurred surgeons to apply similar techniques to other operations. Pioneers in the development of less invasive valve surgery were Dr. Delos M. Cosgrove III at the Cleveland Clinic and Dr. Lawrence H. Cohn at Harvard-affiliated Brigham and Women’s Hospital. Since the late 1990s, the two surgeons and their teams have performed several thousand minimally invasive aortic and mitral valve surgeries. The procedures used in the two centers are much the same.

The surgeon starts by making an incision two to three inches long in the middle of the chest, exposing part of the breastbone (sternum) beneath (see figure). He or she then cuts through the top or the bottom of the sternum, depending on whether the operation is for the aortic or mitral valve, and spreads the ribs. About half of the sternum stays together, one thing that makes recovery easier.

With the heart exposed, the surgical team uses miniature instruments to connect it to a heart-lung bypass machine, stops the heart’s steady beat, and opens the heart. If the aortic valve is failing, it is removed and a new one — either a mechanical valve or a biological one — is sewn in place. Failing mitral valves can often be repaired with a few well-placed stitches. When that isn’t possible, a new valve can be put in place. Once the valve has been repaired or replaced, the heart is closed up, restarted, and disconnected from the bypass machine. The breastbone is wired together and the incision sewn up.

Assuming all goes well, the procedure takes about three hours.

Meeting the test

The true test of a new operation is how well it stacks up against the current
standard procedure. That’s a tough test for minimally invasive valve procedures, since the full procedure is a tried-and-true operation that works exceedingly well. For the 100,000 or so operations done each year to repair or replace faulty valves, survival with the full procedure is high, about 96% (higher in centers where it is done often, lower where it isn’t).

The Brigham and Women’s team has been publishing results of its minimally invasive approach from the beginning. Survival rates for the more than 2,000 minimally invasive operations to date beat the national average for the full procedure — 98% for minimally invasive aortic valve surgery and 99% for mitral valve procedures. Time spent on the heart-lung bypass machine is no longer, and is often shorter, than with full open-heart surgery. People stay fewer days in the hospital recovering from minimally invasive valve surgery and are more likely to go home than to a nursing home or rehabilitation center. They report less pain, easier breathing, and better mobility from the smaller operation.

“The bottom line is that patients recover faster with the minimally invasive operation,” says Dr. Cohn. He’s not just reciting dry statistics when he says that. When he needed his aortic valve replaced, he chose to have it done via the minimally invasive route. “I was back doing heart surgery in three weeks.”

Minimally invasive valve surgery may be especially appropriate for older people. Doctors sometimes hesitate to do open-heart surgery in people over age 75 or 80 who have symptoms of valve trouble but who are doing “okay.” Delaying the operation can lead to irreversible damage to the valves and heart. In a review of 1,000 minimally invasive aortic valve operations done at Brigham and Women’s Hospital, survival, hospital stays, and recovery were every bit as good among those over age 80 as they were for the entire group.

Keep in mind that no one has done a trial directly comparing minimally invasive valve surgery with the traditional operation. It is possible that the results wouldn’t be quite so good. That said, the results from these two high-volume centers show the promise of this approach.

Discussion points

Minimally invasive valve surgery isn’t for everyone. It shouldn’t be done for
someone who needs multiple valves fixed, or who needs bypass surgery or an operation to stop atrial fibrillation along with valve replacement or repair. It also can’t be done if the surgeon can’t get access to the heart or valves through a smaller incision, as may be the case for people who are obese or who have a deformity in the chest wall.

As is true for every operation, minimally invasive valve surgery takes practice and repetition. If you are considering having it instead of full open-heart surgery, don’t be afraid to ask your surgeon how many minimally invasive valve operations he or she has done. Ask how long his or her patients are on the heart-lung bypass machine, and what their survival rate is.

At a number of medical centers, surgeons are using robot-assisted surgery to repair or replace a mitral valve without splitting the breastbone at all. Instead, tiny tools are inserted into the heart through a small incision and two punctures in the side of the chest. Hoping to skip surgery altogether, researchers and medical device companies are racing to fix faulty valves from the inside, using a procedure akin to artery-opening angioplasty. While appealing from the recovery standpoint, these even more minimal approaches have yet to be compared to full or minimally invasive valve surgery. We’ll take a look at them in a future issue.