Restoring the Rhythm

 

Warren L. Jackman, MD
Director of the Heart Rhythm Institute 


Others call it his "sixth sense," and even cardiologist Warren L. "Sonny" Jackman, M.D., acknowledges that "I can see things sometimes in electrocardiograms recorded within the heart [that show] where the problem is."

The "things" that Jackman is world famous for "seeing" are the clumps of cells responsible for short-circuiting the heart's normal rhythms and sending them into wildly chaotic and life-threatening bursts of activity.

At precisely the spot where Jackman detects the problem, he and his cardiologist colleagues work a catheter snug against it and let fly with a radiofrequency current that burns away the offending tissues. Gone is tissue no bigger than a pea. Gone, too, is the problem.

This ability to use the heart's own electrical signals to find and eliminate the source of cardiac arrhythmias has earned Jackman a global reputation - and OU College of Medicine's Heart Rhythm Institute - credit for giving new hope to millions.

Jackman's success in curing many types of heart rhythm disturbances results from a combination of instinct, technique and more than two decades of collaboration between Jackman, his clinical colleagues and the research scientists on the team. Together they made the Department of Internal Medicine's Cardiovascular Section, and more recently the Heart Rhythm Institute, prime examples of translational, bench-to-bedside research programs.

With a foot in both clinical and basic research camps is Regents Professor Ralph Lazzara, M.D., holder of the Natalie O. Warren Chair in Medicine, who co-directs the Heart Rhythm Institute with Jackman.

When Lazzara arrived at the OU Health Sciences Center in 1978 as chief of the cardiovascular section of the Department of Internal Medicine, electrocardiographer Robert Bayley, M.D., had already established the program's national reputation in research on the electrical activity of the heart and its expression in the electrocardiogram as a diagnostic tool.

Accompanying Lazzara to Oklahoma, and destined to help him take the program to new heights, was Benjamin Scherlag, Ph.D.

Scherlag was already widely known in the 1960s for discovering a way to record the electrical signal from the bundle of His with a catheter placed in the femoral vein. It is the His bundle of fibers that carries an electrical impulse from the upper to the lower pumping chambers of the heart to ensure the sequence of the heart's contractions. Scherlag's discovery is considered to be the cornerstone for what was to become the new field of clinical electrophysiology.

Then in the 1970s, it was Scherlag, Lazzara and coworkers who clarified many of the mechanisms for cardiac rhythm disturbances associated with myocardial infarction.

Jackman joined the team at OU in 1982. When he later showed that destroying the tissues that produce an abnormal rhythm would eliminate the abnormal rhythm itself, it linked his name forever with the new field of RF ablation. By early 1990s, Jackman had also shown that use of RF ablation could cure Wolff-Parkinson-White Syndrome without the complications associated with surgery or use of high electrical shocks delivered by catheters.

Making it easier for Jackman to pinpoint his ablation targets was Ed Berbari, Ph.D., a biomedical engineer and expert on recording techniques. Under Berbari's tutelage, "we made very small electrodes," Jackman said. "This allowed us to have a much higher resolution of recording, which meant that if we recorded anything [abnormal], the catheter was within two to three millimeters" of the arrhythmia's origin.

"This higher resolution recording, which really began here, in combination with radiofrequency current, made localizing more accurate and the ablation more limited and safer."

Berbari also developed high-resolution electrocardiography.

This major advance in electrocardiography increased the power of recording electrical signals by 1,000 times by boosting detection of signals to 1/1,000,000 of a volt. It not only leads clinicians to the origin of deadly arrhythmias, but is also used to predict the risk of their development.

Another key player was Will Webster, an inventive engineer who owned a small company making custom heart catheters and who supplied Jackman with the catheters needed to advance the field of RF ablation. It was Webster who created the closely spaced electrodes for mapping, and he later invented a steerable electrode catheter that could map and pinpoint defective tissues in the heart.

Webster's decades-long support and significant donations helped to establish the Heart Rhythm Institute in 2000 and bring clinicians and scientists under one roof.

One of them is Hiroshi Nakagawa, M.D., described by Jackman as a world leader in developing the "maps" that recreate the electrical activation of the chamber during tachycardia, even in scarred atria and scarred ventricles, to expose targets for ablation. Nakagawa helped design and test in animals many of the latest catheters and tools.

As the basic and clinical research teams were advancing the field in mapping and ablation techniques, Lazzara was discovering the cellular mechanism that causes Long Q-T Syndrome, a congenital and abnormal repolarization of the heart resulting in sudden death in young people. This new mechanism was also operative in fatal rhythm disturbances caused by certain drugs.

In the early 1970s, Scherlag and Lazzara discovered clusters of nerve cells that affected the function of specialized regions of the heart.

For the past seven years, Scherlag has devoted his energies to understanding the role of the intrinsic nervous system of the heart in general and the nerve clusters on the atria called the autonomic ganglionated plexi in particular. Last year, Scherlag and Sunny Po, M.D., Ph.D.,showed in animals that targeting autonomic nerves and ganglia on the heart, within the pericar-dium, can suppress atrial fibrillation with little, if any, damage to the healthy myocardium.

This is wonderful news for the estimated 2.2 million Americans with atrial fibrillation, Jackman said. "It was found 10 years ago that A-fib begins with rapid firing from a thin sleeve or atrial muscle that extends out into the pulmonary veins. The first real ablation treatment was to create a circular lesion around the pulmonary veins to isolate them electrically from the rest of the heart, but it was not effective in everyone.

"What we've found is that we can use the same techniques which we found to work in animal experiments to locate the plexi. We'll ablate there in addition to isolating the pulmonary veins," Jackman said. "It appears to increase the likelihood of success by 10 to 20 percent."

The patients who have benefited from CARI's research and treatment number in the thousands and represent all 50 states and 16 other countries. Professional colleagues, too, come to Oklahoma City for training, development and evaluation.

Jackman and colleagues have helped train 1,200 physicians and scientists in his methods.

This willingness to share techniques with the competition is surprising to some, but Jackman said, "We thought we should teach everything we knew." Now, at least 70 percent of his patients are difficult or potentially dangerous cases referred by those who came to CARI for training.

Jackman's determination to give other, less-experienced physicians the tools they need to cure arrhythmias is reflected in his pioneering work with a new, automatic, magnetic fielddriven mapping system that should boost success rates "at centers that don't have extremely skilled individuals."

Last June, Jackman became the first in the country to perform fully automated mapping and treatment when he ablated the extra fiber of muscle connecting upper and lower heart chambers in a teenage boy with Wolff-Parkinson-White Syndrome. In this case, the cause of the boy's WPW was in a difficult location to reach.

OU Medical Center had earlier become the second hospital in the world to install magnetic navigation technology that allows physicians to move a catheter robotically to difficult-to-reach places in the heart. To treat his young patient, Jackman decided to combine this stereotaxis technology with new, Global Position System-type technology developed by Biosense Webster. A sensor on the tip allows three small GPS-type, magnetic field transmitters to triangulate and detect the location of the catheter at all times.

No physician was touching the teenage patient nor the catheter during the procedure to map electrical activity in the heart, detect the source of the problem or ablate the offending tissues.

"This is the beginning of truly automatic mapping which will allow physicians, even those with a lot less experience, to be able to perform these procedures," Jackman said. "This technology will allow us to get to places we have never been before inside the heart. It will become the standard of care."