Acute limb heating improves macro- and microvascular dilator function in the leg of aged humans.

Local heating of an extremity increases blood flow and vascular shear stress throughout the arterial tree. Local heating acutely improves macrovascular dilator function in the upper limbs of young healthy adults through a shear stress-dependent mechanism but has no such effect in the lower limbs of this age group. The effect of acute limb heating on dilator function within the atherosclerotic prone vasculature of the lower limbs of aged adults is unknown. Therefore, the purpose of this study was to test the hypothesis that acute lower limb heating improves macro- and microvascular dilator function within the leg vasculature of aged adults. Nine young and nine aged adults immersed their lower limbs at a depth of ~33 cm into a heated (~42°C) circulated water bath for 45 min. Before and 30 min after heating, macro (flow-mediated dilation)- and microvascular (reactive hyperemia) dilator functions were assessed in the lower limb, following 5 min of arterial occlusion, via Doppler ultrasound. Compared with preheat, macrovascular dilator function was unchanged following heating in young adults (P = 0.6) but was improved in aged adults (P = 0.04). Similarly, microvascular dilator function, as assessed by peak reactive hyperemia, was unchanged following heating in young adults (P = 0.1) but was improved in aged adults (P < 0.01). Taken together, these data suggest that acute lower limb heating improves both macro- and microvascular dilator function in an age dependent manner. NEW & NOTEWORTHY: We demonstrate that lower limb heating acutely improves macro- and microvascular dilator function within the atherosclerotic prone vasculature of the leg in aged adults. These findings provide evidence for a potential therapeutic use of chronic lower limb heating to improve vascular health in primary aging and various disease conditions.

Relative changes in flow velocities in vasospasm after subarachnoid hemorrhage: a transcranial Doppler study.

INTRODUCTION: Transcranial Dopplers (TCDs) have been used to monitor cerebral blood flow velocities in subarachnoid hemorrhage (SAH).The purpose of our two-part study was to compare the reliability of relative increases in flow velocities with conventionally used absolute flow velocity indices and to correct for hyperemia-induced flow velocity change. METHODS: Part 1: Charts of 50 patients admitted to Hahnemann University Hospital with aneurismal SAH were reviewed. Mean middle cerebral artery maximum flow velocities (MCA-MFV) were reviewed for initial flow velocities (IFVs) and maximal flow velocities (MFVs) that were reached during hospital course. Correlating flow velocities (SFVs) were noted in patients who developed symptomatic vasospasm. MFV/IFV and SFV/IFV ratios were calculated to evaluate relative changes in flow velocity. Part 2: Correction for hyperemia was derived from Lindegaards Ratio using extracranial internal carotid artery (ICA) flow velocity ratio (corrected MCA-MFV/observed MCA-MFV = EC-ICAFV (day1)/observed EC-ICAFV). RESULTS: Part 1: All 10 patients who developed symptomatic vasospasm exhibited a twofold increase (SFV/IFV: >2) in flow velocities prior to developing symptomatic vasospasm, and 5 patients had a threefold increase (SFV/IFV: >3). Of the 40 patients who did not develop symptomatic vasospasm, 33 patients did not have a twofold increase in their flow velocities at any time. The positive predictive value for MFV/IFV greater than 3 (n = 6) and SFV/IFV greater than 3 (n = 5) was 100%. The negative predictive value for MFV/IFV less than 2 (n = 33) was 100%. Data using relative changes (twofold increase) in flow velocity was more sensitive (100 to 90%), specific (83 to 70%), and predictive (positive predictive value [PPV]: 59 to 45%; negative predictive value [NPV]: 100 to 97%) for symptomatic vasospasm than absolute flow velocity indices using MCA-MFV greater than 120 even in combination with Lindegaards Ratio (MCA/ICA greater than 3). Part 2: Correction for hyperemia by modifying Lindegaard's Index in the 32 patients where data was available improved the PPV of absolute flow velocities from 44 to 62%. In this population, the application of this equation while evaluating relative change in flow velocities improved PPV of twofold increase from 57 to 73%. CONCLUSION: Relative changes in flow velocities in patients with aneurysmal SAH correlated better with clinically significant vasospasm than absolute flow velocity indices. Correction for hyperemia improved predictive value of TCD in vasospasm.

Prediction of hyperperfusion after carotid endarterectomy by brain SPECT analysis with semiquantitative statistical mapping method.

BACKGROUND AND PURPOSE: Hyperperfusion syndrome is a rare but disastrous complication after carotid endarterectomy (CEA). The aim of this study was to investigate the relationship between preoperative cerebral blood flow (CBF) abnormalities and postoperative hyperperfusion through the use of statistical brain mapping analysis. METHODS: For 41 patients with unilateral carotid stenosis >or=70%, CBF and cerebral vasoreactivity (CVR) were investigated with resting and acetazolamide-challenge single photon emission CT before CEA. CBF 1 day after CEA was also measured. Three-dimensional stereotactic surface projection (3D-SSP) analysis of CBF changes was performed by use of a control database of 20 subjects. RESULTS: Patients with reduced CVR (CVR <10%, n=15) were categorized into 2 groups based on the severity of CBF reduction relative to the control database by 3D-SSP analysis without normalization: type I (ipsilateral CBF decrease <20%, n=8) and type II (ipsilateral CBF decrease >or=20%, n=7). With thalamic normalization, the patients were also categorized into 2 groups: type A (ipsilateral Z score 2, n=5). Severe CBF reduction (>or=20% or Z score >2) was significantly associated with postoperative hyperperfusion (CBF increase >or=100%). However, 3D-SSP with thalamic normalization (Z score) demonstrated a higher predictive value (80%) and specificity (91%) for hyperperfusion than 3D-SSP without normalization (percent reduction) (57% and 73%, respectively). No patients with normal CVR (CVR >or=10%, n=26) demonstrated postoperative hyperperfusion. CONCLUSIONS: Objective evaluation of abnormalities of CBF and CVR with 3D-SSP could identify patients at risk for postoperative hyperperfusion.

Improvement of early functional atherosclerotic changes in males with hypercholesterolemia after vitamin E supplementation.

Vitamin E as an antioxidant vitamin reduces the susceptibility of low-density lipoprotein (LDL) cholesterol to oxidation and may have antiatherosclerotic effects. We tested the hypothesis that six months of 400 mg vitamin E supplementation favourably affects early functional changes in atherosclerotic process in subjects with hypercholesterolemia. The diameter of the brachial artery at rest, after reactive hyperemia (representing endothelium-dependent vasodilatation) and after sublingual glyceryl-trinitrate (representing endothelium-independent vasodilatation), were determined by ultrasonographic method (B mode) before and after the intervention period. After the intervention period the brachial endothelium-dependent vasodilatation increased significantly in the vitamin E group while it did not change in the placebo group. In conclusion, six months of oral vitamin E supplementation results in improvement of the endothelium-dependent vasodilatation in men with hypercholesterolemia.

Hyperperfusion in the lateral temporal cortex, the striatum and the thalamus during complex visual hallucinations: single photon emission computed tomography findings in patients with Charles Bonnet syndrome.

We report the findings of single photon emission computed tomography using 123I-IMP and magnetic resonance image studies of five patients with Charles Bonnet syndrome (CBS) while they were having visual hallucinations. All patients developed complex visual hallucinations after suffering from eye disease. The mean age at onset of CBS was 71.6 years. Single photon emission computed tomography studies in all patients disclosed hyperperfusion areas with some asymmetrical appearances in the lateral temporal cortex, striatum and thalamus. These results suggest that when elderly people suffer from eye disease, subsequent excessive cortical compensation in the lateral temporal cortex, striatum and thalamus may precipitate the development of visual hallucinations.

99mTc-bicisate and 99mTc-HMPAO SPECT imaging in early spontaneous reperfusion of cerebral embolism.

Two patients with a cerebral embolism were evaluated by using both 99mTc-ethyl cysteinate dimer (ECD, or Bicisate) and 99mTc-hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT). In one patient, 99mTc-ECD SPECT images revealed hypoactivity in a reflow hyperemic area where an infarct was seen later on CT scans. In another patient, a reperfused area showed hyperactivity on 99mTc-ECD SPECT without any abnormality on follow-up CT. 99mTc-ECD represents a potential agent with which to evaluate cerebral tissue viability in early reperfusion after ischemia.

Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 5. Lower extremity blood flow and hyperemic responses to occlusion are augmented by ambulation training.

OBJECTIVE: To test whether 12 weeks of exercise conditioning using functional neuromuscular stimulation (FNS) ambulation alters the resting lower extremity blood flow and hyperemic responses to vascular occlusion in subjects with paraplegia, and to determine whether an association exists between limb flow and lower extremity fat-free mass. DESIGN: Pretest, posttest. SETTING: Academic medical center. PARTICIPANTS: Subjects with chronic neurologically complete paraplegia. INTERVENTION: Thirty-two sessions of microprocessor-controlled ambulation using electrically stimulated contractions of lower extremity muscles and a rolling walker. OUTCOME MEASURES: Subjects underwent quantitative Doppler ultrasound examination of the common femoral artery (CFA) before and after training. End-diastolic arterial images and arterial flow-velocity profiles obtained at rest and after 5 minutes of suprasystolic thigh occlusion were computer-digitized for analysis of heart rate (HR), CFA peak systolic velocity (PSV), CFA cross-sectional area (CSA), flow velocity integral (FVI), pulse volume (PV), and CFA (arterial) inflow volume (AIV). RESULTS: Significant effects of training on CSA (p < .0001), FVI (p < .05), computed PV (p < .001), and computed AIV (p < .01) were observed. Resting HR was lower following training (p < .05). The change for resting PSV approached but did not reach significance (p = .083). Analysis of postocclusion PV and AIV showed significant effects for conditioning status (p values < .01), postcompression time (p values < .0001), and their interaction (p values < .01). At 1 minute after occlusion, the posttraining AIV response was 78.2% greater in absolute magnitude and 17.4% more robust when expressed as a percentage change from its resting value than before training. Significant correlations were found between thigh fat free mass and both AIV and PV (p values < .05). CONCLUSION: Exercise training using FNS ambulation increases the resting lower extremity AIV in individuals with paraplegia and augments the hyperemic response to vascular occlusion. Improved posttraining blood flow is attributable both to vascular structural changes and upregulation of vascular flow control mechanisms. Limb mass is associated with the volume of arterial blood flow.

Appendicitis: usefulness of color Doppler US.

PURPOSE: To assess whether color Doppler ultrasonography (US) can help diagnose early acute appendicitis in appendices of equivocal size at gray-scale US. MATERIALS AND METHODS: In a retrospective study, color Doppler US findings were evaluated in 20 individuals with proved normal appendix at barium enema examination and in 50 patients in whom pathologic findings confirmed acute appendicitis. In a prospective study, the diagnostic value of hyperemia in the wall of the appendix in differentiating a normal from an inflamed appendix was evaluated in 26 patients with appendices of equivocal size (5-7 mm in maximal outer diameter) at grayscale US. RESULTS: In the retrospective study, 44 of the 50 patients had hyperemia at color Doppler US. The remaining six patients had no hyperemia, and pathologic findings confirmed gangrenous appendices. The 20 patients with proved normal appendix at barium enema examination had no detectable blood flow in the wall. In the prospective study, 10 of 26 patients had hyperemia at color Doppler US, and pathologic findings confirmed early acute appendicitis. Results of barium enema examination (n = 12) or clinical follow-up (n = 4) confirmed no appendicitis in the remaining 16 patients. CONCLUSION: Hyperemia in the wall of the appendix at color Doppler US is a sensitive indicator for inflammation. A simple additional color Doppler US examination may be helpful in the diagnosis of early acute appendicitis when an appendix is well depicted and is equivocal in size at gray-scale US.