Lifewatch: Stress test can detect type of heart failure

Reported by Claire Hosmann - email
Posted by Debra Worley - email

(WECT) - More than 5 million Americans are living with heart failure, but now there is a way to detect one of the leading causes of the condition without going inside the heart.

56-year-old Shellie Green worries about her health and is getting a nuclear stress test designed to find blockages.

Now, researchers have discovered the same test can also determine if Shellie has one of two types of heart failure.

More than 50% of people with heart failure have the diastolic type.  That's when the left side of the heart doesn't pump enough blood, leading to a buildup of blood in the lungs.

"The heart can pump the blood to all different organs as much as it receives," said cardiologist Dr. Dineshkumar Patel.  "If heart cannot receive enough blood, it will not pump as much as it would like to."

Before the discovery diagnosis was difficult.  Doctors used echocardiograms or had to thread a catheter into the heart, which was too invasive for some patients.

In the new test, doctors inject radioactive dye into a vein, allowing them to take pictures of the heart.  Researchers say they stress test correctly diagnosed patients 94% of the time.

Dr. Patel says you can be in great physical shape, but still have a heart dysfunction.  The new test allows doctors to prevent heart failure before patients start complaining of chest pain and feeling out of breath.

For more information, please contact:
Amy Connell, Media Relations Specialist
Medical College of Georgia

BACKGROUND: Heart failure occurs in roughly one out of 100 people. A total of almost five million Americans are suffering from the progressive condition. In heart failure, the heart cannot pump blood efficiently, leading to reduced blood flow and a buildup of blood in the veins and lungs, which further weakens the heart. There are two types of heart failure: systolic and diastolic.

Systolic heart failure occurs because the heart cannot contract normally. It may fill with blood but cannot pump it out of the heart, reducing the amount of blood the body and lungs receive. Blood accumulates in the lower chambers of the heart, called the ventricles and can then buildup in the lungs, veins or both.

Diastolic heart failure occurs because the heart muscle becomes stiff and unable to relax after contracting. Specifically, the left ventricle becomes stiff. The heart is able to pump enough blood out of the ventricles, but is not able to pump enough blood into it, preventing it from filling normally. As in systolic heart failure, this causes blood to back up into the lungs or veins.

According to a study published in the New England Journal of Medicine, the prevalence of people suffering from diastolic heart failure is growing and now accounts for more than half of heart failure cases. The study involved 4,596 heart failure patients discharged from two Mayo Clinic Hospitals between 1987 and 2001. Over three consecutive five-year periods, diastolic heart failure increased from 38 percent to 47 percent to 54 percent. Diastolic heart failure affects women more often than men, particularly elderly women.

DIAGNOSING HEART FAILURE: Physicians can more easily test the systolic function of a heart, i.e. how well it pumps, using an echocardiogram or cardiac catheterization. In an echocardiogram, a technician moves a handheld device across the chest. The device sends sound waves through the front of the chest and bounces off of the heart to create an image of it beating. Cardiac catheterization is a more invasive test. A thin plastic tube is inserted into an artery or vein in the arm or leg and threaded into the chambers of the heart. A dye is injected into the catheter to allow doctors to view the arteries and the structure of the heart via X-ray. For some, this test is too invasive.

Researchers have discovered a new way to detect diastolic heart failure. A nuclear stress test can show how fast blood is flowing into the heart's left ventricle, or pumping chamber, to see if it is pumping well. During the stress test, radioactive thallium is injected into the bloodstream. After a person does an exercise test, scans are taken to show how the heart works when it's stressed. Two or three hours later another scan is taken to show how the heart pumps when it is at rest. "If someone has a slow fill rate, that means the left ventricle is not relaxed enough to get enough blood, and if the left ventricle cannot receive enough blood, then it cannot collect enough blood to be pumped to the rest of the body," Dineshkumar Patel, M.D., a cardiology fellow at the Medical College of Georgia, in Augusta, Ga., was quoted as saying. The nuclear stress test was originally designed to detect heart blockages. According to Dr. Patel, patients with coronary disease who also have diastolic dysfunction are four times more likely to die.