Posts Tagged ‘Congneital Heart Defect’

No more heart transplants?

July 13, 2010

Will heart transplants one day be a thing of the past?

I think the answer is yes – one day. Not today, and certainly not tomorrow. But there are a lot of options being worked on that hopefully one day will help patients avoid a heart transplant. One of these we have discussed before: The Ventricular Assist Device, or VAD. The VAD is a small pump that is surgically implanted into the body and connects the ventricle to the Aorta. Technically, they can assist either ventricle, but the majority of them are connected to the Left Ventricle, the name “Left Ventricle Assistance Device” and the acronym LVAD are sometime used to discuss any variety of the pumps.

The LVAD was originally thought of as a temporary device to be used to assist a heart until a transplant organ became available, a “bridge to transplant” option. But the units have improved so much that today they are also considered as a permanent implant – “Destination Therapy” that will allow the patient to resume his or her life. With that viewpoint in mind, two important tests have recently begun.

HeartWare International recently won approval from the Food and Drug Administration (FDA) to test their LVAD system as a Destination Therapy device. HeartWare has plans to select 450 patients at 50 U.S. hospitals for the study. Patients must be in “end stage heart failure who have not responded to standard medical management and who are ineligible for cardiac transplantation.” Every patient enrolled in the study will receive an LVAD. Two thirds of them will receive HeartWare’s system, while the rest receive any other FDA-approved LVAD. The study is expected to last at least two years.

Meanwhile, World Heart Corporation is testing its new LVAD, the Levacor VAD. The Levacor VAD unit is being tested as a bridge to transplant only right now, but it is a pretty amazing little machine. The Impeller (a rotor inside the unit; the part that actually pushes the blood through) doesn’t touch anything – it is suspended in place by magnets above and below it. It turns smoother, and since it doesn’t rub against another part it should never wear out. And it is small, too – the unit is about the size of a hockey puck.

The drawback is that both LVADs require battery packs that are outside the body. Unlike pacemakers, no one has been able to implant a LVAD battery unit in the body yet. But I think that is coming, though I can’t predict when.

Partners of the Heart

November 24, 2009

In honor of Red and Blue Day, what follows is a reprint of an article I wrote for the November 2009 issue of The Right Heart Times, the newsletter of the CHD support group Hypoplastic Right Hearts:

The Blalock-Taussig Shunt (Shunt means “detour”) was the brainchild of one of the most unusual people in medicine: Dr. Helen Taussig. Despite being Dyslexic and slowly losing her hearing after becoming a doctor, Taussig had overcome both disabilities to become the head of the Cardiac unit at the Harriet Lane Home for Invalid Children, located at Johns Hopkins Hospital in Baltimore, Maryland.

While at Harriet Lane she began to study Congenital Heart Defects, especially Tetralogy of Fallot (ToF). ToF children suffered from a combination of four heart defects which led to the mixing of oxygenated blood with unoxygenated blood inside their damaged hearts. This caused them to have Cyanosis (have a bluish tinge to their skin due to poor blood oxygenation), have poor stamina, difficulty feeding and usually die before they reached ten years old.  Despite the fact that these children were breathing hard and deep, they were suffocating – and there was nothing that Dr. Taussig could do about it.

Taussig’s frustration would continue until 1943, when Hopkins hired Dr. Alfred Blalock as the new Chief of Surgery. It wasn’t long after his arrival that Taussig and Blalock had a conversation that would change the world.

Hopkins legend states that Dr. Taussig literally broke into a conversation between Dr. Blalock and her boss, Dr. Edwards Park, and convinced him to attempt a surgical repair of the defect. Blalock reminded her that it was impossible to operate on the heart (at that time it was impossible) but Taussig contended that what she had in mind was not an operation on the heart itself, but moving the blood vessels around to send more blood to the lungs. She had the idea, but since she was not a surgeon she could not act on it.

Little did she know that he already had a partial answer. While studying the effects of shock on the human body, Blalock and his assistant Vivien Thomas had sewn a smaller artery onto the Pulmonary Artery in an attempt to increase blood pressure. Blood pressure had not been affected, but blood flow increased. The challenge now was to recreate the effects of ToF in a dog, perform the arterial connection, and evaluate the results. Swamped with his teaching duties and surgical schedule, Blalock turned the assignment almost completely over to Thomas. An African American with a high school education, Thomas had gotten a job in Blalock’s lab after dropping out of college and had become Blalock’s most able assistant.

Re-creating either the heart defect or the planned repair often proved fatal for the dog, but finally Thomas found the perfect combination and a mutt named Anna survived. The next step was to teach Blalock the procedure. The surgeon had observed the operation several times but had never done it himself; Thomas had done the procedure several hundred times – all on dogs.

On November 29, 1944, the trio tried the new surgery. They may have operated sooner than they wanted to, but young Eileen Saxon’s condition was deteriorating. Although she was 15 months of age, Eileen weighed only nine pounds and was badly cyanotic.

As they were preparing for surgery, Blalock turned to his scrub nurse and quietly asked her to summon Mr. Thomas. Although Thomas had taught him the procedure, he wanted his assistant close by in case there was a problem. Thomas entered the surgical suite and stood behind Blalock, guiding him through the operation and giving advice.

Making a five-inch incision on Eileen’s left side, Blalock clamped and cut her Left Subclavian Artery. The Left Subclavian branches off of the Aorta, travels along the shoulder blade (the Clavicle) and down the left arm. For a visual reference, the Left Subclavian Artery is located almost directly behind a police officer’s badge.
Blalock then placed clamps on the left branch of the Pulmonary Artery and made a small hole in the artery. Gently pulling the Subclavian downward, Blalock sewed the vessel onto the Pulmonary Artery, took a deep breath, and disconnected the clamps.

Eileen’s cyanosis almost instantly faded. “She’s a lovely color now!” Taussig exclaimed. Blalock’s surgical notes are a bit more understated, reporting that “the circulation in the nail beds of the left hand appeared to be fairly good at the completion of the operation.”

Originally known as a “subclavian to pulmonary anastomosis,”the operation was soon renamed the Blalock-Taussig Shunt, after the surgeon who performed it and the doctor who conceived it. Thomas received almost no credit for his part of the procedure during his lifetime.

Survivors of the Blalock-Taussig Shunt often have difficulty getting a pulse or a blood pressure reading in the arm on the shunt side (because of the disconnected Subclavian Artery) and should avoid having injections into that arm. In the late 1970’s the Modified Blalock-Taussig Shunt (MBTS) became popular. The MBTS leaves the Subclavian intact and makes the Subclavian-Pulmonary connection by inserting an artificial tube and avoids the arm problems created by the original Blalock-Taussig.
Eileen Saxon did well for a few months but again became Cyanotic as her shunt failed. She underwent another Blalock-Taussig Shunt (on her right side this time) but passed away just before her third birthday.

Blalock’s surgical team performed almost 200 Shunts in the space of a single calendar year and the operation opened the door for Congenital Cardiac Surgery. He continued to operate until just before his retirement in 1964, and died six months later.

Dr. Helen Taussig became known as “the Mother of Pediatric Cardiology” and had a part in averting the Thalidomide crisis in the early 1960’s. She retired in 1963 but often returned to Hopkins, staying current on the latest Cardiac research and contributing  much of it herself. She was killed in an automobile accident in May of 1986.

Vivien Thomas continued to stand at Blalock’s shoulder and eventually became Director of the Johns Hopkins Hospital Surgical Research Laboratories. He trained many of the surgeons who would become famous for their heart surgery accomplishments and invented many of the procedures that they would use. He received an honorary doctorate in 1976 and retired in 1979. Thomas wrote his autobiography, Partners of the Heart: Vivien Thomas and his work with Alfred Blalock and died in 1985, just before the book was published.

Anna the Dog served as the mascot of the Johns Hopkins Surgical Labs until her death in 1957.