Usha Tedrow, MD, did not set out to become a physician. Born and raised in the Boston area, Tedrow studied electrical engineering as an undergraduate at MIT. A college mentor who was an MD/PhD was the first person to nudge Tedrow in the direction of medicine. But Tedrow never lost her interest in things electric. As the director of the Clinical Cardiac Electrophysiology Fellowship Program and the clinical director of the Ventricular Arrhythmia Program for the Cardiac Arrhythmia Service, Tedrow continues to find wonder in electricity.
“Electrophysiology is a little bit like magic,” she said. “In essence, the heart is a pump that needs electrical activation to make it work. We have many ways of making pictures of the heart as a pump (ultrasound, MRI, CT scans) but none of these tell us about the way electrical signals move through the heart. By placing electrodes in and around the heart, you can see characteristic signals that tell us where normal and abnormal pathways or electrical connections are. Then, a procedure called an ablation can be performed to eliminate the abnormal tracts. Some of these procedures are done to improve quality of life and some are done to save the patient’s life.”
Taking a Beat
Tedrow’s clinical interests include supraventricular tachycardia, atrial fibrillation, and ventricular tachycardia (VT), all of which relate to abnormalities in the pattern of the beating of the heart, otherwise known as arrhythmias. Arrhythmias can be treated with catheter ablation, a minimally invasive procedure aiming to eliminate abnormal electrical activity in the heart. Catheter ablation came into medical practice in the 1980s, and since that time, clinicians have refined their techniques to treat more and complex arrhythmias.
Tedrow’s specialty is VT, a condition in which the lower chamber of the heart beats too fast to pump blood well. The patient can lose consciousness, develop heart failure or even die as a consequence. VT can result when the heart muscle has been injured, most often by a heart attack. Other diseases that damage the heart muscle (cardiomyopathies) can also cause VT. Catheter ablation can be used to treat VT by cauterizing or freezing heart tissue to correct abnormal electrical signaling. But when the area of interest is deep within the wall of the heart, cardiologists need specialized strategies to reach the right location.
Tedrow learned VT ablation from William G. Stevenson, MD, the former director of the Brigham’s Cardiac Arrhythmia Program.
“I met Bill Stevenson during my fellowship and he was internationally known as a leader in electrophysiology,” said Tedrow. “I realized this field could bring together what I had learned in my old life of electrical engineering with my new life in medicine.”
Inventions and Investigations
Stevenson invented an investigational needle catheter — a new type of ablation catheter that has a needle that is inserted near a target site and then floods the site with contrast/saline, allowing ablation to be performed within the wall of the heart. The Brigham is one of three hospitals in the U.S. using the investigational needle catheter to treat patients with VT for whom medications and standard ablation techniques have not worked. Tedrow and colleagues are using the experimental irrigated needle catheter under an Investigational Device Exemption (IDE) from the FDA. To date, they have performed investigational VT catheter ablations in about 40 patients in whom standard ablation approaches and medications have been unsuccessful. Two-thirds have shown long-term improvement after six months.
Tedrow credits this success to the multi-disciplinary team approach taken by the Cardiac Arrhythmia Service. This includes specialized experts in heart failure, cardiac critical care, cardiac genetics and cardiac sarcoidosis, to name a few. The team also collaborates with experts in other departments including anesthesiologists that can perform sympathetic blocks and cardiac surgeons who can help patients who may need a ventricular support device or heart transplant after they have been stabilized.
“This can be a challenging disease and patients are very sick, but our preliminary data have been really promising in improving outcomes,” Tedrow said.
Exploring the Depths of the Heart
Tedrow is currently researching left ventricular mapping and imaging data to analyze novel ablation treatments for structural heart disease.
“My research interests dovetail with my clinical work using the needle catheter and imaging,” she said. “We’re looking at cases where we are still not able to be successful. The better we understand where the arrhythmias are coming from in these patients, the more successful we’ll be at treating them in the future.”
Currently, most 3D maps of electrical activation of the heart are generated by moving the catheter around the surface of the heart. But seeing how electrical signals move deeper into the walls of the heart has been more difficult, especially in patients who may have tiny localized scar tissue deep in their heart muscle that can hide from standard catheters and mapping techniques. Tedrow is looking for ways to predict the locations of those scars, and the origin points of arrhythmias, based on the electrical measurements from the needle catheter and more detailed imaging.
“The goal of our research is to find strategies to better treat those whom we haven’t been able to treat as well,” said Tedrow.
Tedrow also runs the fellowship training program in electrophysiology and enjoys the opportunity to mentor fellows and teach techniques as well as share her research interests.
“We have lots of irons in the fire,” said Tedrow. “It’s an honor and a privilege to mentor others, and an exciting time to be working in the field and at the Brigham.”