Peripheral arteriosclerosis; arterial grafting procedures; indications and results. II. Arteriosclerotic arterial occlusion

Arteriosclerotic thrombotic lesions involving the arteries to the lower extremities may be conveniently grouped into three categories. Lesions of the aorta-common-iliac level (Category I) appear to be most satisfactorily treated by thromboendarterectomy. Lesions in the femoral artery (Category II) are particularly amenable to bypass arterial grafts. Advanced lesions (Category III) involving both areas may be treated by one or the other method or a combination of both. Aortography is a necessary prerequisite in the selection of patients for operation and the determination of the method of surgical approach.     

Lower limb co-contraction during walking in subjects with stroke: A systematic review

PurposeThe aim of this paper was to identify and synthesise existing evidence on lower limb muscle co-contraction (MCo) during walking in subjects with stroke.MethodsAn electronic literature search on Web of Science, PubMed and B-on was conducted. Studies from 1999 to 2012 which analysed lower limb MCo during walking in subjects with stroke, were included.ResultsEight articles met the inclusion criteria: 3 studied MCo in acute stage of stroke, 3 in the chronic stage and 2 at both stages. Seven were observational and 1 had a pretest–posttest interventional design. The methodological quality was “fair to good” to “high” quality (only 1 study). Different methodologies to assess walking and quantify MCo were used. There is some controversy in MCo results, however subjects with stroke tended towards longer MCo in both lower limbs in both the acute and chronic stages, when compared with healthy controls. A higher level of post-stroke walking ability (speed; level of independence) was correlated with longer thigh MCo in the non-affected limb. One study demonstrated significant improvements in walking ability over time without significant changes in MCo patterns.ConclusionsSubjects with stroke commonly present longer MCo during walking, probably in an attempt to improve walking ability. However, to ensure recommendations for clinical practice, further research with standardized methodologies is needed.     

Hemodynamic basis of renal arteriosclerosis in young greyhounds

Renal arteriosclerosis occurs with unusually high frequency in young race-trained greyhounds. Light and electron microscopic studies were used to examine the arterial walls of renal vessels in six greyhounds. Lesions characteristic of mechanical forces, namely pressure and shear stresses, were found consistently on the endothelial surfaces of damaged vessels. Such damage was found in both the main renal vessel and its branches. Although the patterns of endothelial damage showed quantitative differences among individuals, the qualitative features were remarkably similar in the group. Quantitatively, fibrous plaques were greatest in narrow and curved portions of renal vessels. The plaques were found on the outer luminal surface of the bend and the bifurcation segments, but were absent on the flow dividers. Hemodynamic forces appear to play an important role in the pathogenesis of renal fibrous plaques. Renal arteriosclerosis in greyhounds provides an excellent model for the study of pressure pulse velocity and shear stress damage under various physiological conditions.     

Histamine-induced pulmonary edema distal to pulmonary arterial occlusion

Histological studies provide evidence that the bronchial veins are a site of leakage in histamine-induced pulmonary edema, but the physiological importance of this finding is not known. To determine if a lung perfused by only the bronchial arteries could develop pulmonary edema, we infused histamine for 2 h in anesthetized sheep with no pulmonary arterial blood flow to the right lung. In control sheep the postmortem extravascular lung water volume (EVLW) in both the right (occluded) and left (perfused) lung was 3.7 +/- 0.4 ml X g dry lung wt-1. Following histamine infusion, EVLW increased to 4.4 +/- 0.7 ml X g dry lung wt-1 in the right (occluded) lung (P less than 0.01) and to 5.3 +/- 1.0 ml X g dry wt-1 in the left (perfused) lung (P less than 0.01). Biopsies from the right (occluded) lungs scored for the presence of edema showed a significantly higher score in the lungs that received histamine (P less than 0.02). Some leakage from the pulmonary circulation of the right lung, perfused via anastomoses from the bronchial circulation, cannot be excluded but should be modest considering the low pressures in the pulmonary circulation following occlusion of the right pulmonary artery. These data show that perfusion via the pulmonary arteries is not a requirement for the production of histamine-induced pulmonary edema.     

Venous occlusion to the lower limb attenuates vasoconstriction in the nonexercised limb during posthandgrip muscle ischemia.

We investigated the effects of increases in calf volume on cardiovascular responses during handgrip (HG) exercise and post-HG exercise muscle ischemia (PEMI). Seven subjects completed two trials: one control (no occlusion) and one venous occlusion (VO) session. Both trials included a baseline measurement followed by 15 min of rest (REST), 2 min of HG, and 2 min of PEMI. VO was applied at 100 mmHg via cuffs placed around both distal thighs during REST, HG, and PEMI. Mean arterial pressure, heart rate, forearm blood flow (FBF) in the nonexercised arm, and forearm vascular resistance (FVR) in the nonexercised arm (FVR) were measured. During REST and HG, there were no significant differences between trials in all parameters. During PEMI in the control trial, mean arterial pressure and FVR were significantly greater and FBF was significantly lower than baseline values (P < 0.05 for each). In contrast, in the VO trial, FBF and FVR responses were different from control responses. In the VO trial, FBF was significantly greater than in the control trial (4.7 +/- 0.5 vs. 2.5 +/- 0.3 ml x 100 ml(-1) x min(-1), P < 0.05) and FVR was significantly lower (28.0 +/- 4.8 vs. 49.1 +/- 4.6 units, respectively, P < 0.05). These results indicate that increases in vascular resistance in the nonexercised limb induced by activation of the muscle chemoreflex can be attenuated by increases in calf volume.     

Upper limb muscle volumes in adult subjects

Muscle force-generating properties are often derived from cadaveric studies of muscle architecture. While the relative sizes of muscles at a single upper limb joint have been established in cadaveric specimens, the relative sizes of muscles across upper limb joints in living subjects remain unclear. We used magnetic resonance imaging to measure the volumes of the 32 upper limb muscles crossing the glenohumeral joint, elbow, forearm, and wrist in 10 young, healthy subjects, ranging from a 20th percentile female to a 97th percentile male, based on height. We measured the volume and volume fraction of these muscles. Muscles crossing the shoulder, elbow, and wrist comprised 52.5, 31.4, and 16.0% of the total muscle volume, respectively. The deltoid had the largest volume fraction (15.2%+/-1%) and the extensor indicis propius had the smallest (0.2%+/-0.05%). We determined that the distribution of muscle volume in the upper limb is highly conserved across these subjects with a three-fold variation in total muscle volumes (1427-4426cm(3)). When we predicted the volume of an individual muscle from the mean volume fraction, on average 85% of the variation among subjects was accounted for (average p=0.0008). This study provides normative data that forms the basis for investigating muscle volumes in other populations, and for scaling computer models to more accurately represent the muscle volume of a specific individual.     

Strength training reduces arterial blood pressure but not sympathetic neural activity in young normotensive subjects.

The effects of resistance training on arterial blood pressure and muscle sympathetic nerve activity (MSNA) at rest have not been established. Although endurance training is commonly recommended to lower arterial blood pressure, it is not known whether similar adaptations occur with resistance training. Therefore, we tested the hypothesis that whole body resistance training reduces arterial blood pressure at rest, with concomitant reductions in MSNA. Twelve young [21 +/- 0.3 (SE) yr] subjects underwent a program of whole body resistance training 3 days/wk for 8 wk. Resting arterial blood pressure (n = 12; automated sphygmomanometer) and MSNA (n = 8; peroneal nerve microneurography) were measured during a 5-min period of supine rest before and after exercise training. Thirteen additional young (21 +/- 0.8 yr) subjects served as controls. Resistance training significantly increased one-repetition maximum values in all trained muscle groups (P < 0.001), and it significantly decreased systolic (130 +/- 3 to 121 +/- 2 mmHg; P = 0.01), diastolic (69 +/- 3 to 61 +/- 2 mmHg; P = 0.04), and mean (89 +/- 2 to 81 +/- 2 mmHg; P = 0.01) arterial blood pressures at rest. Resistance training did not affect MSNA or heart rate. Arterial blood pressures and MSNA were unchanged, but heart rate increased after 8 wk of relative inactivity for subjects in the control group (61 +/- 2 to 67 +/- 3 beats/min; P = 0.01). These results indicate that whole body resistance exercise training might decrease the risk for development of cardiovascular disease by lowering arterial blood pressure but that reductions of pressure are not coupled to resistance exercise-induced decreases of sympathetic tone.     

Haemodynamic response to exercise in healthy young and elderly subjects

Whereas with advancing age, peak heart rate (HR) and cardiac index (CI) are clearly reduced, peak stroke index (SI) may decrease, remain constant or even increase. The aim of this study was to describe the patterns of HR, SI, CI, arteriovenous difference in oxygen concentration (C _a-vO₂), mean arterial pressure (MAP), systemic vascular resistance index (SVRI), stroke work index (SWI) and mean systolic ejection rate index (MSERI) in two age groups (A: 20–30 years, n = 20; B: 50–60 years n = 20. After determination of pulmonary function, an incremental bicycle exercise test was performed, with standard gas-exchange measurements and SI assessment using electrical impedance cardiography. The following age-related changes were found: similar submaximal HR response to exercise in both groups and a higher peak HR in A than in B[185 (SD 9) vs 167 (SD 14) beats · min⁻¹, P < 0.0005]; increase in SI with exercise up to 60–90 W and subsequent stabilization in both groups. As SI decreased towards the end of exercise in B, a higher peak SI was found in A [57.5 (SD 14.0) vs 43.6 (SD 7.7) ml · m⁻², P < 0.0005]; similar submaximal CI response to exercise, higher peak CI in A [10.6 (SD 2.5) vs 7.2 (SD 1.3) l · min⁻¹ · m⁻², P < 0.0005]; no differences in C _a-vO₂ during exercise; higher MAP at all levels of exercise in B; higher SVRI at all levels of exercise in B; lower SWI in B after recovery; higher MSERI at all levels of exercise in A. The decrease in SI with advancing age would seem to be related to a decrease in myocardial contractility, which can no longer be compensated for by an increase in preload (as during submaximal exercise). Increases in systemic blood pressure may also compromise ventricular function but would seem to be of minor importance. Accepted: 24 September 1996     

Factors associated with early atherosclerosis and arterial calcifications in young subjects with a benign phenotype of obesity

We assessed (i) the association between early arterial disease and factors linked to adiposity, dietary habits, and family in a young cohort of 151 obese children and adolescents with less than or equal to one cardiovascular (CV) risk factor, (ii) whether in subjects with carotid calcifications there was an imbalance of calcium‐phosphorus homeostasis. Measurement included: carotid ultrasound, oral glucose tolerance test, anthropometry, body composition, dietary history, white blood cells count, lipids, uric acid, adiponectin, insulin, C‐reactive protein, plasminogen activator inhibitor 1 (PAI‐1), 25‐hydroxyvitamin D, parathyroid hormone (PTH), calcium and phosphorus. Obese children with carotid artery intima media thickness (cIMT) values >75° percentile (0.55 mm), compared to those with lower cIMT, were more obese, more often pubertal and had higher prevalence of family history of CV disease (CVD) (P < 0.05), higher plasma PAI‐1 and uric acid (P < 0.001) and lower adiponectin (P < 0.05) and high‐density lipoprotein (HDL) cholesterol levels (P < 0.05). After adjustment for sex, age, puberty, obesity, and insulin levels, only PAI‐I remained significantly different between the two groups (10.9 (7.2–29.8) vs. 6.2 (4.3–10.6) ng/ml, P < 0.001). Dietary intake did not affect cIMT values. Eight percent of subjects showed nonatherosclerotic carotid calcifications with patchy pattern. These children had a worse lipid profile (P < 0.05) and higher plasma PTH levels (48.6 ± 21.5 vs 38.5 ± 16.9 pg/ml, P < 0.05) that were inversely associated with 25‐hydroxyvitamin D levels (r = 0.245, P < 0.01). Present results suggest that (i) several adiposity‐related factors may play a role in promoting the development of early arterial diseases in young subjects with a benign phenotype of obesity, (ii) a PTH rise resulting from a subclinical imbalance in calcium‐phosphorus homeostasis may affect the biological process of vascular calcifications.     

Results of surgical and conservative treatment for multi-level atheromatous arterial occlusion of the lower limb after five years]

After 5 years of observation, materials of 239 patients treated operatively and 96 patients treated conservatively because of multisegmental arterial occlusion of lower limbs were obtained within the framework of multi-central programme of investigation. The results of the treatment with these methods have been evaluated according to the site of the atheromatous changes and the degree of ischemia of lower limbs. It has been ascertained, that after operative therapy, the percentage of good results and the percentage of death in the case of occlusion comprising the aorto-ilio-femoral segment is higher than in the case of occlusion of femoro-popliteal and peripheral segments, whereas in the case of conservative therapy, the situation is reverse. The results of therapy (operative and conservative) of multilevel arterial occlusion, in all kinds of location, depend upon blood supply in the limbs. The results are best (the highest percentage of good results and without improvement, the least number of amputation and death) in the II period of disease and they become worse when the degree of ischemia increases. It appears that the operative therapy is less effective than the conservative therapy in the case of atheromatous multilevel changes manifesting clinically in the form of intermittent claudication, whereas in the case of the IV degree of ischemia, only the operation can save the limb or even the patient's life.