Mayo Clinic researches ways to better treat patients with heart defects

January 13, 2004

ROCHESTER, Minn. -- In studies appearing in the January issue of Mayo Clinic Proceedings, Mayo Clinic researchers report on procedures that were successful in closing an opening in the heart that fails to completely close after birth in approximately one-fourth of the United States population.

Using a new ultrasound probe developed at Mayo Clinic for use inside the heart, researchers were able to get better images of the defect. The defect, known as patent foramen ovale (PFO), is an opening or flap in the wall of the heart, which did not close completely after birth. The flap may allow blood to cross from the right (venous) side to the left (arterial) side of the circulation, allowing clots to get into the arterial circulation, which can move to the brain, causing a stroke. The chance of developing some blood clots in the venous system increases as the person ages.

"By using this special catheter inside the heart we are able to visualize defects in the walls between various chambers, measure their size and observe the placement of newly developed devices to close the defects with catheter techniques," said Donald Hagler, M.D., a pediatric cardiologist at Mayo Clinic and one of the authors of the two studies.

The Mayo Clinic Proceedings report is designed to help physicians understand the method and how to get the necessary pictures to do such procedures.

The intracardiac echocardiographic guidance gives physicians greater visual confirmation of the defects in the atrial walls. They don't need to use other ultrasound techniques such as transesophageal echocardiography (TEE), which is much more uncomfortable for the patient. Most patients have to be heavily sedated to tolerate having the TEE probe in place in the esophagus. Researchers said the major limitations with TEE include the use of general anesthesia and potential problems related to management of the patient's breathing while sedated.

Others who authored the study are: Michael Earing, M.D., Allison Cabalka, M.D., James Seward, M.D., Charles Bruce, M.D., and Guy Reeder, M.D., all of Mayo Clinic.

In the second report, researchers discuss a follow-up study of 103 patients at Mayo Clinic whose PFO was closed with a catheter device. The results showed that the cardiologists were very effective (93 percent) in completely closing the PFO. There were very few complications and only three patients had difficulties later.

The device closure offers the chance of avoiding the need for long-term medication. Others involved in the study are: Anant Khositseth, M.D., John Sweeney, M.D., David Fortuin, M.D., Heidi Connolly, M.D., Allison Cabalka, M.D. and Guy Reeder, M.D., of the Mayo Clinic College of Medicine. Dr. Khositseth is now with Ramathibodi Hospital in Bangkok, Thailand.

Harold Adams Jr., M.D., of the Department of Neurology at the University of Iowa's Carver College of Medicine, writes in an editorial in the same issue of Mayo Clinic Proceedings that the studies provide additional information needed for researchers to understand the best treatment for patients with this defect. However, he said further studies are needed.

"We cannot assume that all patients with patent foramen ovale and neurologic symptoms need to have the cardiac abnormality corrected," Dr. Adams writes. "Some patients might benefit substantially from closure of their patent foramen ovale; however, the procedure might be unnecessary in other patients. The neurology and cardiology communities need to collaborate in clinical studies to prospectively test the safety and efficacy of patent foramen ovale closure devices."

Dr. Adams is an investigator in CLOSURE, a trial sponsored by the NMT Corporation, which is one of the current trials comparing the placement of closure devices to best medical treatment for patients with PFO.
A peer-reviewed journal, Mayo Clinic Proceedings publishes original articles and reviews dealing with clinical and laboratory medicine, clinical research, basic science research and clinical epidemiology. Mayo Clinic Proceedings is published monthly by Mayo Clinic as part of its commitment to the medical education of physicians. The journal has been published for more than 75 years and has a circulation of 130,000 nationally and internationally.

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