Dr. David Lan, electrophysiologist at the Memphis Heart Clinic. He is performing a catheter study on this patient to determine problem areas.
With the exception of the 1918 flu pandemic, cardiovascular disease has been the number one cause of death in the United States for more than a century. The latest American Heart Association studies estimate that 1.2 million Americans will have new or recurrent coronary attacks in 2006. Of these, 500,000 will have a recurrent attack. While it is recognized that public health challenges such as diabetes, obesity and untreated high blood pressure hamper the prevention of heart disease, there have been significant advancements and improvements in the quality of care and survival after a heart attack. Technological advancements such as high-speed, multi-slice CT scanners, echocardiograms and calcium scoring, all of which are widely utilized today, have provided cardiologists greater clarity and precision with interventional procedures. Additionally, new medicines are making life after a heart attack much easier for patients.
One group that is working to make interventional procedures easier for patients is the Memphis Heart Alliance. Three clinics joined forces in 1999 to develop this outpatient diagnostic cardiac cath lab. Physicians from Cardiology Associates of Memphis, Stern Cardiovascular Center and Sutherland Cardiology Clinic share space on the St. Francis Hospital campus to provide basic procedures for stable patients in a timelier manner than hospitals are able to accommodate. Physicians manage their own patients and personnel.
"It is a slow but growing trend to have outpatient cath labs," explains Dr. Larry Spiotta, interventional cardiologist at Stern. "There is frequent scheduling trouble at hospitals. This takes the diagnostic patients out of the emergency space and puts them in an environment where we have more control."
From angiograms and catheterizations to angioplasty of the legs, the Memphis Heart Alliance provides multiple techniques approved for outpatient use. A unique therapy offered at the alliance includes the successful yet seldom utilized enhanced external counterpulsation (EECP). EECP is a mechanical procedure in which long inflatable cuffs are wrapped around both of the patient's legs. While the patient lies on a bed, the leg cuffs are inflated and deflated with each heartbeat. This is accomplished by a computer, which triggers off the patient's ECG so that the cuffs deflate just as each heartbeat begins, and inflate just as each heartbeat ends. The inflation is done in a sequential motion, essentially "milking" blood in the legs upward, towards the heart. This therapy is mainly used for patients who continue to have symptoms despite invasive intervention.
EECP is reported to have two potentially beneficial actions on the heart. First, the milking action of the leg cuffs increases the blood flow to the coronary arteries. Second, by its deflating action just as the heart begins to beat, EECP creates something like a sudden vacuum in the arteries, which reduces the work of the heart muscle in pumping blood into the arteries. Both of these actions have long been known to reduce cardiac ischemia in patients with coronary artery disease; however, an invasive procedure that does the same thing, intra-aortic counterpulsation, has been in widespread use in intensive care units for decades, and its effectiveness in stabilizing patients is well known. While external counterpulsation is an older technique, it has not been very effective until recently. Thanks to new computer technology that allows the perfect timing of the inflation and deflation of the cuffs and that produces the milking action, modern EECP has been greatly enhanced.
EECP is administered as a series of outpatient treatments. Patients receive five one-hour sessions per week for seven weeks, for a total of 30-35 one-hour sessions. The sessions are aimed at provoking long lasting beneficial changes in the circulatory system. Studies have also shown EECP to be beneficial in patients with angina.
Research is advancing the scope of cardiology with studies underway in new devices, biological treatments, genomics and preventive medications. A quick conversation with Dr. Frank McGrew, director of clinical research at Stern Cardiology Group, reveals a long list of up and coming research. Some of the latest studies include research on pacemakers and cholesterol medication. One major trial that concluded last year found a pattern in heart muscle weakness that was successfully overridden by a new automatic defibrillator.
"We found that if you look at patients with heart muscle weakness, whatever the cost, half of the time it's high blood pressure, half of the time it's artery blockage," McGrew explains. "Putting an automatic defibrillator in those patients reduced the death rate significantly."
For patients with a moderate amount of heart muscle weakness, the study showed that placing the defibrillator reduced the death rate by 30 percent. This suggests any patient who's had a major heart attack and is left with significant scarring or weakness needs the defibrillator.
"That's still an unacceptably high death rate but it was a major advance that's going to have a tremendous affect on healthcare," he adds.
A more recent study looks at the Optimizer™ pacemaker, which is designed to make the heart beat stronger rather than faster by emitting a low-level electrical current. This study involves patients whose heart rates are not too slow but their muscle is too weak.
Stern also participates in numerous prevention trials, many of which deal with treating atherosclerosis. A current Phase II trial involves an intravenous infusion of a synthetic form of HDL, which is given to patients weekly. A different study involves an oral medication designed to shift cholesterol metabolism from LDL to HDL in the bloodstream. Physicians then use ultrasound to analyze the artery plaques.
In the future, Stern will be involved in studies designed to determine differences of acuity and prevalence between races. They have already concluded a study on congestive heart failure within a significant number of African American patients. This study involved the drug BiDil, which was shown to be of major benefit in reducing hospitalization and death rates.
"We don't really know, in terms of calcium scoring, which scores are for predictions and risk in African Americans," says McGrew. "We're trying to get some data for race."
On the horizon is research into genomics and stem cell capabilities. McGrew says the research team at Stern Cardiovascular Center is looking deeper into genomic studies that identify, through a patient's genome, how the patient may respond to one medication over another, thus creating a more targeted, more individualized approach. There is also talk of a vaccine to prevent cholesterol deposits in the arteries. And McGrew acknowledges human research isn't far away from stem cell regeneration work for a weakened heart muscle.
What can be assessed from all this research? The overall the risk of heart failure is down due to life-saving technology and preventive medications. The flip-side: chronic heart failure sufferers are an ever-increasing portion of the patient population.
"The risk of major heart attacks is substantially lower than it used to be," McGrew says. "We have life-saving techniques but we don't have completely successful muscle-saving techniques. That's why there is a lot of emphasis on heart failure research. Heart disease is a public health concern and it takes better diet and exercise, medical investigation, finding new drugs and being more precise in applying the drugs we do have to manage heart disease."
A clinic that prides itself for being on the cutting-edge of technology is Memphis Heart Clinic. More than a year ago, Baptist Memorial Health Care-Memphis, where the clinic is located, purchased a Stereotaxis™ Magnetic Navigation System. This one-of-a-kind system, designed for patients with arrhythmia, uses powerful magnets to guide a catheter or guide wire through a patient while interventional cardiologists or electrophysiologists navigate the guide wires from a control center. With this system, doctors no longer have to stand over a patient for hours, manually guiding a difficult-to-maneuver cath, but instead use a joystick and computer controls to remotely navigate the cath. Not only is procedure time reduced but both staff and patients have reduced exposure to radiation. Physicians are able to specify device direction and movement with point-and-click navigation tools. High-tech flat-panel monitors are fully integrated with these tools to deliver outstanding spatial and contrast resolution for enhanced diagnostic confidence. Fluoroscopy and color mapping are still used in conjunction with the system. The navigation tools allow physicians to pinpoint problem areas and make minute movements, thus improving the accuracy and stability of these procedures. The system has been commonly used to install biventricular pacemakers and defibrillators but the uses are expanding.
Electrophysiologist Dr. David Lan at Memphis Heart Clinic has been using the magnetic navigation system for a year now and is especially pleased with the evolving abilities it presents for patients with atrial fibrillation, an affliction affecting more than two million Americans. He has conducted the first ablation procedures with a new catheter, the Celsius™ Diagnostic and Ablation Catheter, designed for use with the magnetic navigation system. This catheter directs radio frequencies into the heart and delivers a current through the tip to burn heart tissue.
"Atrial fibrillation is one of the hardest topics in cardiology because it is a very common problem," Lan says. "It has been a challenge to do more catheter ablations for atrial fibrillations. It's an evolving technique. We're trying to make the procedure more routine and available.
"You can do all these procedures without the magnetic system," he adds, "but the system is evolving the concept."
There is no doubt that there are benefits in reduced exposure to radiation and more efficient arrhythmia treatment procedures, but time will determine who is best suited for treatment via magnetic navigation.
Through years of research, effort and greater awareness of health issues, cardiology is viewed with full-circle vision for prevention. The local chapter of the AHA is working on a legislative agenda to improve public health policies in Tennessee. This agenda includes restoring and retaining physical education to public schools, maintaining pressure on tobacco regulation and continuing stroke systems of care. By working together with physicians, educators and legislators, the AHA hopes to bring about healthy changes in individuals. With greater involvement in prevention, outreach and treatment, physicians play a vital role in positively affecting the heart health of the Memphis community.