Cardiovascular Health after Cancer: Challenges and Strategies
Barbara Natterson, MD, Associate Professor of Medicine, Director of Imaging for the UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine, and Cardiologist
This is a summary of a lecture presented on February 10, 2009.
With more than 10.6 million cancer survivors in the Unites States, having researchers and clinicians tending to the cardiovascular needs of these patients is very important. All parts of the cardiovascular system can be affected by chemotherapy, radiation, and surgery. While we have known for some time that some anti-cancer therapies can affect cardiac function, patients may have little choice other than to take these drugs because they are the most effective treatments to address their cancer. The risk/benefit analysis may focus on life preserving treatments for cancer not on potential health problems at a later time. Patients should and can be informed about the effects of cancer therapies on their cardiac function, the types of alterations that may occur because of their treatments and should advocate that they receive full and high quality assessments of cardiac function and treatment.
The cardiac system is made up of the ventricles, conduction system, the pericardium and the autonomic nervous system. The heart is a large muscle that contracts and relaxes, pumping blood through the various chambers of the heart and back out to the lungs, carrying oxygen to the body. The ventricles are the pumping mechanisms which are stimulated by the conduction system or electrical circuitry. The electrical system is measured by an EKG (electrocardiogram) which determines whether the heart is beating too fast or too slowly. The valves connect the different chambers; they open and close, keeping the blood flow going in one direction. The heart is encased in a sack called the pericardium. The arteries are the large vessels that bring blood to the heart.
Ejection fraction (EF) is a measurement that tells your physician the capacity at which your heart is pumping. During each heartbeat cycle there are two phases, systole (when the heart contracts) and diastole when the heart relaxes. When the heart contracts, it ejects blood from the ventricles which are called the chambers in the heart. When the heart relaxes the ventricles refill with blood. No matter how strong or forceful the contraction is, having some blood remaining in the ventricle is normal. Ejection fraction is the term used to refer to the percentage of blood that is pumped out of a filled ventricle with each heartbeat during systole. The left ventricle is the heart’s main pumping chamber, and ejection fraction is usually calculated using this ventricle, hence the name left ventricular ejection fraction. A normal ejection fraction is considered to be approximately 60-65% of the blood leaving the chamber after systole. Normal diastolic function is identified by specific parameters on an echocardiogram. Focusing on the “ejection fraction” only tells part of the picture of how the heart is really doing. The diastolic assessment is just as important in post-cancer patients.
Cancer Treatments May Have Effects on Different Aspects of the CV System
Cancer treatment related cardiovascular issues can affect all parts of the CV system. The coronary arteries may be prematurely blocked due to some therapies, potentially leading to heart attacks and angina. The ventricles may become weakened due to some therapies leading to congestive heart failure. The conduction system (electrical system) may be damaged due to some therapies potentially leading fainting or the need for pacemakers. The pericardial sac (in which heart is contained) may become damaged due to other treatments. The autonomic nervous system, which encompasses the neurological control of most of the functioning of our bodies, can also be affected adversely.
Notably, both the contraction phase of the cardiac cycle (systole) and the relaxation phase of the cardiac cycle (diastole) may be adversely affected by some cancer treatments. Echocardiography can identify abnormalities in both systolic and diastolic function if performed properly.
Heart Recommendations for Cancer Survivors
As a cancer survivor you should be actively involved in your follow-up care. Here are some suggestions:
Editors Note: For assistance with dietary issues, consider seeing the Integrative Medicine Physician, Dr. Mary Hardy in the Simms/Mann – UCLA Center for Integrative Oncology who does educational sessions to help patients and their families make healthy choices related to nutrition and dietary supplementation (310 794-6644). Also, be aware that the VITA program through the UCLA LiveSTRONG Center for Excellence in Survivorship is available to assist in assessing and making recommendations for survivorship screening and assessment (310-825-9781).