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Monday, May 17, 2010
Diagnosis of heart failure is growing, with about 670,000 new cases in the United States each year. About 300,000 Americans die annually from the condition. Symptoms such as shortness of breath and fatigue can make it difficult to complete activities of daily living and greatly impede quality of life. As the condition worsens, frequent hospitalizations are necessary to relieve fluid overload or acute pulmonary edema.
Treatment of heart failure includes lifestyle modifications and medication, such as diuretics or ACE inhibitors. The underlying cause of heart failure, such as long-term hypertension, also needs to be addressed. However, as heart failure progresses, these therapies may no longer be effective. As a result, patients with severe heart failure usually require a device to help the heart pump effectively. These devices are not curative, but do prolong and improve life.
A cardiac resynchronization therapy (CRT) device is an implantable biventricular pacing device with three leads (right atrial, right ventricular, and left ventricular) that synchronize ventricular contractions. CRT results in a more efficient heart, reducing heart failure symptoms and improving prognosis. A CRT device can be implanted alone or with an implanted cardioverter defibrillator (ICD)—a device that sends electrical pulses to the heart to correct erratic heart rhythms caused by heart failure.
Remote Monitoring Revolutionizing Device Therapy
In addition to providing potentially lifesaving therapy, implantable devices provide valuable information about the heart—such as heart rate, heart rate variability, arrhythmias, and more. This collection of information helps guide physicians in medication adjustment.
The Mass General Heart Center has been on the leading edge of remote monitoring of these devices. Over the past five years, it has used therapy devices with wireless transmitters that communicate information directly to physician computers. This collection of data allows for more convenient and continuous monitoring of patients.
Recently, the Heart Center has been working to further the field of wireless monitoring by investigating a new device—the left atrial pressure (LAP) sensor device—that provides the most accurate, beat-by-beat information about the heart.
New Sensor Device Provides Direct Cardiac Function Measurement
Through collaborative efforts of the Heart Failure and Cardiac Transplant Program, Cardiac Arrhythmia Service, and Echocardiography Services, the Mass General Heart Center was the first in the Northeast to implant a LAP sensor device. The LAP device continuously monitors the pressure in the left atrium, providing physicians with real-time information about the heart. It provides a direct, invasive, and continuous measurement of left atrial pressure and thereby cardiac function.
The LAP sensor device detects pressure changes in the left atrium on a millimeter-by-millimeter basis. Elevated pressure in the left atrium, however small, is a direct early sign of pulmonary edema. These minute indications allow physicians to be much more aggressive in their heart failure management. Small medication adjustments in response to elevated pressure readings can correct heart function days or weeks before symptoms may appear, helping prevent complications and hospitalizations.
LAP Sensor Device at Work
The Mass General Heart Center interventional electrophysiologists permanently implant a pressure transducer lead into the left atrium, which is fixed onto the interatrial septum. The transducer is connected by a wire to a signal processing device, which is implanted in the pectoral region. To get a pressure reading, the patient positions a small, handheld device over his or her chest where the device is implanted. With a push of a button, the signaling device provides a direct pressure reading of the left atrium. This gives patients real-time information regarding cardiac function. The information can also be transmitted wirelessly to physicians by connecting the signaling device to a synchronizing module attached to the patient’s computer.
Mass General Advancing Sensor Device Research
The Mass General Heart Center was selected as one of five sites for the Homeostasis Study, a pilot study involving the first use of the LAP sensor device. The investigation is now complete and results are pending. However, the Homeostasis Study was successful in gaining FDA approval of the sensor device for use in larger trials.
The Homeostasis Study has spawned a number of other promising studies involving the LAP sensor device. The Heart Center is involved in many of these studies and, most notably, is a principal site for the Laptop Heart Failure Study. The Laptop Heart Failure Study will analyze the LAP sensor device in combination with the CRT device or another implantable device. In the past, the sensor was implanted separately. The goal is to evaluate on a larger scale whether monitoring LAP sensor measurements remotely can help facilitate patients’ involvement in their care, reduce hospitalization, and improve outcomes and mortality.
Empowering Patients in Their Own Care
A primary goal for the LAP sensor device is to help chronic heart failure patients take a more active role in the management of their condition. As part of the Homeostasis Study, the Mass General Heart Center conducted a patient training phase after implantation of the device. Patients were taught how to make medication adjustments in response to small changes in left atrial pressure without the direct intervention of a physician. Although frequent intervention by heart failure specialists is necessary during training and regular monitoring by a physician is needed to ensure appropriate treatment, the training is helping shift more responsibility to patients. The goal of empowering patients to take a greater role in managing their heart failure is continuing through the Laptop Heart Failure Study.
The Mass General Heart Center is known as a leader in the care and treatment of heart failure. The Heart Center is currently involved in approximately 15 investigator-initiated or multicenter device therapy studies focusing on heart failure. Many of the studies are aimed at enhancing patient selection and creating better patient follow-up strategies.
Jagmeet P. Singh, MD, PhDDirector, Cardiac Resynchronization Therapy ProgramMassachusetts General Hospital Heart CenterAssociate Professor of Medicine, Harvard Medical Schooljsingh@partners.org
Massachusetts General Hospital Heart Center
The Massachusetts General Hospital Heart Center is a multidisciplinary program that integrates the experts and services of the divisions of Cardiology, Cardiac Surgery, Cardiac Anesthesia, Cardiac Imaging, and Cardiac Nursing to provide state-of-the-art care for patients with all types of cardiac disorders. Continuing its legacy as a pioneer in cardiac research, the Heart Center also conducts bench-to-bedside research aimed at improving the prevention, diagnosis, and treatment of heart disease worldwide.
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