Vascular Function Can Be Impaired in African-Americans and Women, Study Suggests

 

March 9, 2010

March 2, 2010 — Leg arteries that become narrow decrease blood circulation and can cause these extremities to ache or cramp when a person begins exercise. This condition is referred to as intermittent claudication (IC). Although the pain may subside with rest, IC should be taken seriously because it can increase the risk of heart attack and stroke. One in 10 patients who have peripheral artery disease (PAD) also have IC.

A study in the March Journal of Vascular Surgery, published by the Society for Vascular Surgery, examined the data of 110 PAD patients with IC and differences ethnicity and gender had on their conditions.

According to Andrew W. Gardner, Ph.D. and professor at the General Clinical Research Center at the University of Oklahoma Health Sciences Center in Oklahoma City, the large artery elasticity index (with significant covariates of age and elevated triglycerides) for African-Americans was 39 percent lower than that of the Caucasian patients. There was no significant difference in large artery elasticity index between men and women. However, the small elasticity index, which was adjusted for covariates of age, abdominal obesity, and elevated blood pressure, was 32 percent lower in African-Americans compared to Caucasians and was 18 percent lower in women than in men.

Researchers noted that age was the most significant single covariate for both large and small artery compliance in older patients with PAD and IC. Structural changes within the arterial wall, such as increased fragmentation and decreased density of elastin, as well as increased concentration of collagen and hypertrophy of vascular smooth muscle, contribute to arterial deterioration.

Patients with elevated blood pressure and abdominal obesity had impaired small artery compliance and elevated triglycerides were a final covariate for large arterial compliance after adjusting for age in African-American patients.

"All patients had similar ankle-brachial index (ABI) which measures blood pressure in both the ankle and the arm to help predict PAD," Gardner said. "The ethnic and gender differences in arterial compliance were evident even though ABI measurements were similar among all patients, which suggests that the level of arterial compliance provides unique information to quantify vascular impairment in patients with intermittent IC."

"This is the first study to compare ethnic differences in arterial compliance in PAD patients," added Gardner. "Less compliant large and small arteries of African-Americans may be one factor contributing to their higher risk for PAD as well as to their shorter six-minute walk distance, slower velocity while walking four meters, and a lower summary performance score following testing." Gardner noted that less compliant small arteries in women with IC may also have contributed to reduced circulation in calf muscles, which resulted in a lower exercise performance rate and shorter walking distance.

"The present findings are limited to PAD patients who have IC and may not be generalized to patients with less severe or more severe PAD," he said. "However patients in the study are typical of IC patients because there was a high prevalence of cardiovascular risk factors for PAD including smoking diabetes, hypertension, dyslipidemia and obesity. Thus our findings were generalized to the majority of patients with IC who typically have numerous comorbid conditions."

Future investigations should examine whether arterial compliance is associated with symptomatology and exercise performance, and whether it is modifiable with interventions such as exercise and medication therapies," he added.

For more information: www.VascularWeb.org