Navegando por Palavras-chave "regional blood flow"

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    Comparative blood flow study of arteriovenous fistulae in canine femoral arteries: Modified latero-lateral and end-lateral techniques
    (Blackwell Science Inc, 2000-03-01) Galego, S. J.; Goldenberg, S.; Ortiz, J. P.; Gomes, P. D.; Ramacciotti, E.; Universidade Federal de São Paulo (UNIFESP)
    The aim of this study was to evaluate the blood flow of an arteriovenous fistula comparing the modified latero-lateral (LLM) and end-lateral (TL) techniques in canine femoral arteries. Ten mongrel dogs were submitted to 2 arteriovenous fistulae each, with a LLM on one side and a TL procedure on the other side. Cranial and caudal average blood flow as well as average venous flow were measured by an electronic fluxometer 15, 20, and 25 min after surgery. Mann-Whitney, Friedman, and Wilcoxon nonparametric tests were used for data analysis (alpha less than or equal to 0,05). Femoral artery flow, cranial to the fistula, was increased 5 1/2 times in both groups. in the femoral artery caudal to the fistula, the flow in the majority of the animals was reversed 1.3 times using the TL technique and 2 times using the LLM technique. the average flow in the cranial vein was statistically different with an improved flow of 7.4 times versus 6.8 times for the LLM technique. These results suggest that LLM arteriovenous fistula in dogs leads to a larger venous flow than in the TL arteriovenous fistula and the reverse caudal arterial flow in the latero-lateral technique. the flow behavior (laminar or turbulent) in the 2 types of arteriovenous fistula was studied in terms of singular head loss.
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    Fistula size and hemodynamics: an experimental model in canine femoral arteriovenous fistulas
    (Wichtig Editore, 2007-01-01) Ramacciotti, Eduardo; Galego, Sidnei José; Gomes, Marise; Goldenberg, Saul [UNIFESP]; Gomes, Paulo de Oliveira [UNIFESP]; Ortiz, Jayme Pinto; Universidade Federal de São Paulo (UNIFESP)
    Purpose: The objective was to evaluate the impact of anastomosis diameter on blood flow in an arteriovenous fistula (AVF), comparing two different anastomosis sizes with a modified side-to-side technique in canine femoral arteries.Methods: Ten mongrel dogs were subjected to two AVFs each, both using a modified side-to-side technique. On one side, the anastomosis diameter was 1.5 times the arterial diameter and on the other side 3.0 times the arterial diameter. Mean proximal and caudal blood flow and mean venous flow were measured using an electronic flowmeter 15, 20 and 25 min after surgery. The Mann-Whitney, Friedman and Wilcoxon non-parametric tests were used for data analysis (alpha <= 0.05).Results: Femoral artery flow cranial to the fistula became 5.6 times greater in the 1.5 arterial diameter group, and 8.4 times greater in the 3.0 arterial diameter group, when compared to initial arterial flow. The mean flow in the cranial vein was greater in the 3.0 group (10.09 times greater vs. 6.46 times greater in the 1.5 group). Both in the proximal artery and in the vein there was a significantly greater flow in the group with the larger anastomosis diameter (Wilcoxon test). In the femoral artery caudal to the fistula, the flow in most of the animals was reversed: 3.5 times greater in the 1.5 group and 1.2 times greater in the 3.0 group, without statistical difference.Conclusions: These results suggest that 3.0 times the arterial diameter for the AVF size in dogs leads to greater venous flow than with 1.5 times the arterial diameter, without increasing the reversed flow.
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    Sleep-Disordered Breathing Exacerbates Muscle Vasoconstriction and Sympathetic Neural Activation in Patients with Systolic Heart Failure
    (Lippincott Williams & Wilkins, 2016) Lobo, Denise M. L.; Trevizan, Patricia F.; Toschi-Dias, Edgar; Oliveira, Patricia A.; Piveta, Rafael B.; Almeida, Dirceu Rodrigues de [UNIFESP]; Mady, Charles; Bocchi, Edimar A.; Lorenzi-Filho, Geraldo; Middlekauff, Holly R.; Negrao, Carlos E.
    Background-Sleep-disordered breathing (SDB) is common in patients with heart failure (HF), and hypoxia and hypercapnia episodes activate chemoreceptors stimulating autonomic reflex responses. We tested the hypothesis that muscle vasoconstriction and muscle sympathetic nerve activity (MSNA) in response to hypoxia and hypercapnia would be more pronounced in patients with HF and SDB than in patients with HF without SDB (NoSBD). Methods and Results-Ninety consecutive patients with HF, New York Heart Association functional class II-III, and left ventricular ejection fraction <= 40% were screened for the study. Forty-one patients were enrolled: NoSDB (n=13, 46 [39-53] years) and SDB (n=28, 57 [54-61] years). SDB was characterized by apnea-hypopnea index >= 15 events per hour (polysomnography). Peripheral (10% O-2 and 90% N-2, with CO2 titrated) and central (7% CO2 and 93% O-2) chemoreceptors were stimulated for 3 minutes. Forearm and calf blood flow were evaluated by venous occlusion plethysmography, MSNA by microneurography, and blood pressure by beat-to-beat noninvasive technique. Baseline forearm blood flow, forearm vascular conductance, calf blood flow, and calf vascular conductance were similar between groups. MSNA was higher in the SDB group. During hypoxia, the vascular responses (forearm blood flow, forearm vascular conductance, calf blood flow, and calf vascular conductance) were significantly lower in the SDB group compared with the NoSDB group (P<0.01 to all comparisons). Similarly, during hypercapnia, the vascular responses (forearm blood flow, forearm vascular conductance, calf blood flow, and calf vascular conductance) were significantly lower in the SDB group compared with the NoSDB group (P<0.001 to all comparisons). MSNA were higher in response to hypoxia (P=0.024) and tended to be higher to hypercapnia (P=0.066) in the SDB group. Conclusions-Patients with HF and SDB have more severe muscle vasoconstriction during hypoxia and hypercapnia than HF patients without SDB, which seems to be associated with endothelial dysfunction and, in part, increased MSNA response.