Implantable devices track cardiac events in cancer patients
Cancer survivors are more likely to die from heart disease than cancer; therefore, patients must be closely monitored for heart problems during and after cancer treatment. Such surveillance can be done continuously with new implantable cardiac monitoring devices.
The need for cardiac monitoring is evidenced by estimates of heart failure in cancer patients during chemotherapy; such estimates range from 3% to 50% depending on the drugs used. And the risk of heart disease remains long after the treatment is finished.
“When caring for cancer survivors, it’s important to recognize their vulnerability to atrial fibrillation and heart failure caused by previous chemotherapy and to be vigilant for these heart problems,” said Jean-Bernard Durand, M.D., an associate professor of Cardiology at MD Anderson Cancer Center.
Treatment-related heart problems
Chemotherapy and radiation therapy can increase the risk of cardiovascular problems such as severe hypertension, cardiomyopathy, ischemia, atrial fibrillation and congestive heart failure. Chronic cardiotoxicity can occur within weeks of treatment or up to 20 years after treatment.
The cardiac side effects of systemic drugs vary. Cytotoxic chemotherapeutic drugs such as doxorubicin (and other anthracyclines) cumulatively weaken the heart muscle. Biologic therapies such as trastuzumab also can weaken the heart muscle during treatment, but trastuzumab-related cardiomyopathy is often reversible with medical therapy. Taxanes and other chemotherapeutic drugs cause abnormal heart rhythms during treatment in some patients. And angiogenesis inhibitors can cause blood pressure spikes and increase the risk of blood clots and heart failure.
Radiation therapy can trigger long-term cardiac effects if the heart is incidentally exposed to radiation. These long-term effects include coronary artery disease, damage to the heart valves, damage to the heart’s electrical system, heart muscle stiffening, and inflammation.
Implantable cardiac monitors such as the CardioMEMS system and the Reveal LINQ system can provide diagnostic information that can help physicians monitor patients constantly and remotely to detect cardiac events before they become serious.
The Reveal LINQ system, used to detect abnormal heart rhythms and to monitor unexplained fainting, is implanted just under the skin in the chest in an outpatient procedure that takes less than five minutes. Patients also receive a bedside machine that collects the heart data and sends the data to a central database and directly to the smartphone of the implanting physician. If patients notice a cardiac event symptom, they can press a button on the bedside machine to send a report to the database instantly. Physicians can program the device by setting parameters for how often data are downloaded and what ranges of abnormal heart rhythms warrant notification of the physician and patient by database monitors.
Durand uses the Reveal LINQ system to monitor patients around the world. When a patient in Dubai experienced palpitations, Durand was able to call him to discuss his symptoms. The patient took a beta blocker and thus avoided a trip to the emergency department.
“Patients are monitored and cared for 24/7; even halfway around the world, my patients can feel comfortable knowing that their hearts are constantly being monitored and that I’m always there for them, at any time,” Durand said.
This system also allows physicians to help patients associate what they feel with the data that document cardiac events.
“Patients are often surprised to receive a call from the database service when their heart rates are abnormal. Implantable cardiac monitors help patients understand that they don’t necessarily perceive heart rate spikes.”
Unlike the Reveal LINQ device, the CardioMEMS system does not use batteries and can monitor arterial pressure and heart rate throughout a patient’s lifetime. The CardioMEMS device, about the size of a paperclip, is permanently implanted in the pulmonary artery during a right heart catheterization procedure. The device monitors pressure in the pulmonary artery and transmits data wirelessly to an external electronic system, and then the data are transmitted directly to the physician.
“I can monitor patients on my cell phone,” Durand said. “Once I noticed a 10% increase in arterial pressure in a patient. I called him and advised him to take a water pill; we caught the problem quickly enough to avoid a trip to the emergency room.”