For the current study, researchers examined blood flow in the femoral artery, which delivers a majority of the blood received by the leg. The study involved 30 participants over age 60. Eleven of the participants were healthy, nine had diastolic heart failure and 10 had systolic heart failure.
All participants had a test to measure the volume of oxygen they consumed during exhaustive exercise. They also had a magnetic resonance imaging (MRI) test to assess blood flow through their femoral artery before and after flow was temporarily stopped with a blood pressure cuff. This test measures small changes in the size of the vessel interior and in blood flow velocity.
Patients with both types of heart failure had severely reduced peak oxygen consumption confirming their reduced exercise tolerance. But, surprisingly, blood flow to the legs following release of the occlusion cuff was relatively similar in the healthy participants and in those with diastolic heart failure. It was approximately 75 percent lower in those with systolic failure.
"This is important because exercise intolerance is the primary symptom of patients with diastolic failure," said Hundley. "It suggests that factors other than leg blood flow may be responsible for the severely reduced exercise tolerance in this increasingly important disorder."
The researchers tested to see if other variables such as tobacco use, diabetes, or certain medications could have affected the results. After making these adjustments, the gap in leg blood flow between the two types of heart failure actually widened.
"If these results are confirmed, they could help us turn our attention to evaluating other factors that may contribute to reduced exercise tolerance in diastolic heart failure," said K
Contact: Karen Richardson
Wake Forest University Baptist Medical Center