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Chronic changes in skeletal muscle histology and function in peripheral arterial disease
JOURNAL
324
Abstracts
Chronic changes in skeletal muscle histology function in peripheral arterial disease
and
Regensteiner J, Wolfe1 E, Brass E, Carry M, Ringel S, Hargarten M, Stamm E, Hiatt W. Circulation 1993;87: 413-21. Background: This study addresses changes in muscle histologic condition, biochemistry, and exercise performance in patients with peripheral arterial disease (PAD), compared with normal age-matched controls. Twenty-six patients with PAD were studied, and in 10 patients the disease was predominantly unilateral. The goal of this study was to determine the nature of the muscle dysfunction present in patients with claudication and the impact of factors other than restricted arterial circulation that limit performance capacity. Methodsand Results: Evaluation of the patients included vascular testing, treadmill testing, muscle strength, and endurance testing, as well as cross-sectional area evaluations, and muscle biopsies for both enzymatic and histologic end points. Patients with PAD had an ankle/arm pressure ratio of 0.66 + 0.21 at rest, which fell to 0.27 ? 0.14 after exercise, suggesting a significant degree of vascular compromise. A graded treadmill protocol was performed where patients performed to a maximally tolerated claudication pain and controls exercised to the point of exhaustion. Patients with PAD were able to walk 8.1 2 4.1 minutes in comparison to controls who walked 18.6 * 2.3 minutes. Gastrocnemius muscle strength was 43% less and the anterior tibial strength was 31% less than the corresponding values in control subjects. The gastrocnemius muscle endurance in diseased legs was 38% less than in the controls. Patients with unilateral peripheral arterial disease had a 5O/6reduction in a cross-sectional area of the symptomatic leg compared with the nonsymptomatic leg. In contrast the calf cross-sectional area of the diseased leg was not statistically different from controls because of a wide variation. Muscle biopsies demonstrated significantly more denervation in the symptomatic legs compared with controls, and an overall decrease in the type II fiber area compared with the nonsymptomatic legs or controls. The muscle biopsies did not show any significant difference in citrate (si)-synthase, phosphofructokinase, and lactate dehydrogenase between the diseased legs of patients and control subjects. The ankle-brachial index, a measure of the restriction of the arterial inflow, did not correlate with any changes in muscle histologic condition, enzyme activity, gastrocnemius muscle strength, or peak exercise performance on the treadmill. There was no correlation between enzyme activity and peak treadmill walking time for citrate synthase, phosphofiuctokinase, or lactate dehydrogenase. However, citrate synthase activities in control legs did correlate with peak walking time, suggestive of a training effect. Summary: In summary, this study suggested a significant heterogeneity in the response of muscle to decreased blood flow in patients with PAD. The chronic response was characterized by denervation and a decreased type II muscle
OF VASCULAR
SURGERY August 1994
fiber. These changes associated with muscle atrophy and loss of muscle strength contribute to the overall functional impairment of this population above and beyond the actual impact of decreased blood flow. Paul Walker, A4LI University oi Toronto The Toronto Hospital Toronto, Ontario, Canada
High prevalence of unsuspected abdominal aortic aneurysm in patients with confirmed symptomatic peripheral or cerebral arterial disease MacSweeney MK, Powell 582-4.
STR, O’Meara JT’, Greenhalgh
M, Alexander C, O’Malley RM. Br J Surg 1993;80:
Background: Infrarenal abdominal aortic aneurysms are relatively common and often present with rupture and high rates of mortality (84% to 94%), in contrast with low mortality rates seen with elective aneurysm repair ( < 5%). In this study patients with known peripheral arterial occlusive disease were screened for abdominal aortic aneurysms with physical examination and ultrasonography. Methods and Results: Five hundred sixty-one patients with lower extremity occlusive disease (456) or carotid artery occlusive disease (105) were screened with B-mode ultrasonography for infrarenal abdominal aortic aneurysm. Maximum external anterior-posterior aortic diameter of 3 cm or more was used to define an aneurysm. Of these, 200 nonselected patients underwent physical examination before ultrasonography for documentation of the presence or absence of aneurysms. Aneurysms were present by ultrasonography in 40 of 358 men (11.2%) and 13 of 203 women (6.4%) (total = 53/561; 9.4%). The prevalence of aneurysm was similar in patients with lower limb ischemia (42/456; 9.2%) and cerebrovascular disease (11/105; 10.5%). Most aneurysms (33/53; 62%) were less than 4 cm in size (median size 3.7 cm; range 3 to 6.1 cm). Physical examination detected only 43% of the aneurysms (57% if the aneurysm was 4 cm or greater, 29% if the aneurysm was less than 4 cm). Of 137 patients believed to have normal aortas on physical examination only five were subsequently found to have aneurysms on ultrasonography (specificity = 96%). In those patients who underwent ultrasonography in 1 year (38/53), the mean growth rate was 0.2 cm/year (0.15 cm/year for aneurysms less than 4 cm, 0.27 cm/year for aneurysms greater than 4 cm). Summay: This study is similar to other previous reports in the literature documenting that patients with known peripheral vascular disease frequently have abdominal aortic aneurysms. These aneurysms tend to be small, physical examination is a poor method for detecting aneurysms compared with ultrasonography, and growth rates for these small aneurysms is slow. The authors point out that it is difficult to document benefits of an aneurysm screening program in terms of improved patient outcomes, because small aneurysms enlarge slowly, larger aneurysms
324
Abstracts
Chronic changes in skeletal muscle histology function in peripheral arterial disease
and
Regensteiner J, Wolfe1 E, Brass E, Carry M, Ringel S, Hargarten M, Stamm E, Hiatt W. Circulation 1993;87: 413-21. Background: This study addresses changes in muscle histologic condition, biochemistry, and exercise performance in patients with peripheral arterial disease (PAD), compared with normal age-matched controls. Twenty-six patients with PAD were studied, and in 10 patients the disease was predominantly unilateral. The goal of this study was to determine the nature of the muscle dysfunction present in patients with claudication and the impact of factors other than restricted arterial circulation that limit performance capacity. Methodsand Results: Evaluation of the patients included vascular testing, treadmill testing, muscle strength, and endurance testing, as well as cross-sectional area evaluations, and muscle biopsies for both enzymatic and histologic end points. Patients with PAD had an ankle/arm pressure ratio of 0.66 + 0.21 at rest, which fell to 0.27 ? 0.14 after exercise, suggesting a significant degree of vascular compromise. A graded treadmill protocol was performed where patients performed to a maximally tolerated claudication pain and controls exercised to the point of exhaustion. Patients with PAD were able to walk 8.1 2 4.1 minutes in comparison to controls who walked 18.6 * 2.3 minutes. Gastrocnemius muscle strength was 43% less and the anterior tibial strength was 31% less than the corresponding values in control subjects. The gastrocnemius muscle endurance in diseased legs was 38% less than in the controls. Patients with unilateral peripheral arterial disease had a 5O/6reduction in a cross-sectional area of the symptomatic leg compared with the nonsymptomatic leg. In contrast the calf cross-sectional area of the diseased leg was not statistically different from controls because of a wide variation. Muscle biopsies demonstrated significantly more denervation in the symptomatic legs compared with controls, and an overall decrease in the type II fiber area compared with the nonsymptomatic legs or controls. The muscle biopsies did not show any significant difference in citrate (si)-synthase, phosphofructokinase, and lactate dehydrogenase between the diseased legs of patients and control subjects. The ankle-brachial index, a measure of the restriction of the arterial inflow, did not correlate with any changes in muscle histologic condition, enzyme activity, gastrocnemius muscle strength, or peak exercise performance on the treadmill. There was no correlation between enzyme activity and peak treadmill walking time for citrate synthase, phosphofiuctokinase, or lactate dehydrogenase. However, citrate synthase activities in control legs did correlate with peak walking time, suggestive of a training effect. Summary: In summary, this study suggested a significant heterogeneity in the response of muscle to decreased blood flow in patients with PAD. The chronic response was characterized by denervation and a decreased type II muscle
OF VASCULAR
SURGERY August 1994
fiber. These changes associated with muscle atrophy and loss of muscle strength contribute to the overall functional impairment of this population above and beyond the actual impact of decreased blood flow. Paul Walker, A4LI University oi Toronto The Toronto Hospital Toronto, Ontario, Canada
High prevalence of unsuspected abdominal aortic aneurysm in patients with confirmed symptomatic peripheral or cerebral arterial disease MacSweeney MK, Powell 582-4.
STR, O’Meara JT’, Greenhalgh
M, Alexander C, O’Malley RM. Br J Surg 1993;80:
Background: Infrarenal abdominal aortic aneurysms are relatively common and often present with rupture and high rates of mortality (84% to 94%), in contrast with low mortality rates seen with elective aneurysm repair ( < 5%). In this study patients with known peripheral arterial occlusive disease were screened for abdominal aortic aneurysms with physical examination and ultrasonography. Methods and Results: Five hundred sixty-one patients with lower extremity occlusive disease (456) or carotid artery occlusive disease (105) were screened with B-mode ultrasonography for infrarenal abdominal aortic aneurysm. Maximum external anterior-posterior aortic diameter of 3 cm or more was used to define an aneurysm. Of these, 200 nonselected patients underwent physical examination before ultrasonography for documentation of the presence or absence of aneurysms. Aneurysms were present by ultrasonography in 40 of 358 men (11.2%) and 13 of 203 women (6.4%) (total = 53/561; 9.4%). The prevalence of aneurysm was similar in patients with lower limb ischemia (42/456; 9.2%) and cerebrovascular disease (11/105; 10.5%). Most aneurysms (33/53; 62%) were less than 4 cm in size (median size 3.7 cm; range 3 to 6.1 cm). Physical examination detected only 43% of the aneurysms (57% if the aneurysm was 4 cm or greater, 29% if the aneurysm was less than 4 cm). Of 137 patients believed to have normal aortas on physical examination only five were subsequently found to have aneurysms on ultrasonography (specificity = 96%). In those patients who underwent ultrasonography in 1 year (38/53), the mean growth rate was 0.2 cm/year (0.15 cm/year for aneurysms less than 4 cm, 0.27 cm/year for aneurysms greater than 4 cm). Summay: This study is similar to other previous reports in the literature documenting that patients with known peripheral vascular disease frequently have abdominal aortic aneurysms. These aneurysms tend to be small, physical examination is a poor method for detecting aneurysms compared with ultrasonography, and growth rates for these small aneurysms is slow. The authors point out that it is difficult to document benefits of an aneurysm screening program in terms of improved patient outcomes, because small aneurysms enlarge slowly, larger aneurysms