Gestational lower limb edema and venous reflux in healthy primigravidae.

BACKGROUND: Analyze the association of lower limb edema with venous reflux in healthy primigravidae during pregnancy and in the postpartum. METHODS: Cohort with primigravidae evaluated in the three trimesters of pregnancy and postpartum. Edema was assessed by physical examination. Duplex evaluated venous reflux in both limbs. RESULTS: In the first trimester, no woman presented edema or venous reflux. In the second trimester, venous reflux was found in one patient (5%) and edema was found in four women (20%). Venous reflux and edema were not associated (P=1). In the third trimester, two other patients developed venous reflux (15%) and eleven women developed lower limb edema (55%). Venous reflux and edema were also not associated (P=0.21). In the postpartum period, neither venous reflux nor lower limb edema were found. CONCLUSIONS: In healthy primigravidae, lower limb edema was not associated with venous reflux. Both were present in the second and in the third trimesters of pregnancy and resolved spontaneously in the postpartum period. Both are products of the same physiological changes that occur in pregnancy.

Effects of elevated perfusion pressure and pulsatile flow on human saphenous veins isolated from diabetic and non-diabetic patients.

OBJECTIVE: This study was carried out to determine high pressure and pulsatile flow perfusion effects on human saphenous vein (HSV) segments obtained from diabetic and non-diabetic patients. METHODS: The veins were perfused with oxygenated Krebs solution for 3 h, with a pulsatile flow rate of 100 mL/min and pressures of 250 × 200 or 300 × 250 mmHg. After perfusion, veins were studied by light microscopy; nitric oxide synthase (NOS) isoforms, CD34 and nitrotyrosine immunohistochemistry and tissue nitrite/nitrate (NO(x)) and malondialdehyde (MDA) quantification. RESULTS: Light microscopy revealed endothelial denuding areas in all HSV segments subjected to 300 × 250 mmHg perfusion pressure, but the luminal area was similar. The percentage of luminal perimeter covered by endothelium decreased as perfusion pressures increased, and significant differences were observed between groups. The endothelial nitric oxide synthase (eNOS) isoform immunostaining decreased significantly in diabetic patients' veins independent of the perfusion pressure levels. The inducible NOS (iNOS), neuronal NOS (nNOS) and nitrotyrosine immunostaining were similar. Significant CD34 differences were observed between the diabetic 300 × 250 mmHg perfusion pressure group and the non-diabetic control group. Tissue nitrite/nitrate and MDA were not different among groups. CONCLUSIONS: Pulsatile flow and elevated pressures for 3 h caused morphological changes and decreased the eNOS expression in the diabetic patients' veins.

Pharmacology of the human saphenous vein.

Nowadays, the great saphenous vein is the vascular conduit that is most frequently employed in coronary and peripheral revascularization surgery. It is known that saphenous vein bypass grafts have shorter patency than arterial ones, partly because the wall of the normal saphenous vein has different structural and functional characteristics. The features of this vein can be affected by the large distention pressures it is submitted to during its preparation and insertion into the arterial system. Indeed, a vein graft is subjected to considerable changes in hemodynamic forces upon implantation into the arterial circulation, since it is transplanted from a non-pulsatile, low-pressure, low-flow environment with minimal shear stress to a highpressure system with pulsatile flow, where it undergoes cyclic strain and elevated shear. These changes can be responsible for functional and morphological alterations in the vessel wall, culminating in intima hyperproliferation and atherosclerotic degeneration, which contribute to early graft thrombosis. This review has followed a predetermined strategy for updating information on the human saphenous vein (HSV). Besides presenting the aspects relative to the basic pharmacology, this text also includes surgical aspects concerning HSV harvesting, the possible effects of the major groups of cardiovascular drugs on the HSV, and finally the interference of major cardiovascular diseases in the vascular reactivity of the HSV.

Vascular relaxation of canine visceral arteries after ischemia by means of supraceliac aortic cross-clamping followed by reperfusion.

BACKGROUND: The supraceliac aortic cross-clamping can be an option to save patients with hipovolemic shock due to abdominal trauma. However, this maneuver is associated with ischemia/reperfusion (I/R) injury strongly related to oxidative stress and reduction of nitric oxide bioavailability. Moreover, several studies demonstrated impairment in relaxation after I/R, but the time course of I/R necessary to induce vascular dysfunction is still controversial. We investigated whether 60 minutes of ischemia followed by 30 minutes of reperfusion do not change the relaxation of visceral arteries nor the plasma and renal levels of malondialdehyde (MDA) and nitrite plus nitrate (NOx). METHODS: Male mongrel dogs (n = 27) were randomly allocated in one of the three groups: sham (no clamping, n = 9), ischemia (supraceliac aortic cross-clamping for 60 minutes, n = 9), and I/R (60 minutes of ischemia followed by reperfusion for 30 minutes, n = 9). Relaxation of visceral arteries (celiac trunk, renal and superior mesenteric arteries) was studied in organ chambers. MDA and NOx concentrations were determined using a commercially available kit and an ozone-based chemiluminescence assay, respectively. RESULTS: Both acetylcholine and calcium ionophore caused relaxation in endothelium-intact rings and no statistical differences were observed among the three groups. Sodium nitroprusside promoted relaxation in endothelium-denuded rings, and there were no inter-group statistical differences. Both plasma and renal concentrations of MDA and NOx showed no significant difference among the groups. CONCLUSION: Supraceliac aortic cross-clamping for 60 minutes alone and followed by 30 minutes of reperfusion did not impair relaxation of canine visceral arteries nor evoke biochemical alterations in plasma or renal tissue.

Catastrophic cardiovascular adverse reactions to protamine are nitric oxide/cyclic guanosine monophosphate dependent and endothelium mediated: should methylene blue be the treatment of choice?

Clinical and experimental observations prove that heparin-neutralizing doses of protamine increase pulmonary artery pressures and decrease systemic BP. Protamine also increases myocardial oxygen consumption, cardiac output, and heart rate, and decreases systemic vascular resistance. These cardiovascular effects have clinical consequences that have justified studies in this area. Protamine adverse reactions usually have three different categories: systemic hypotension, anaphylactoid reactions, and catastrophic pulmonary vasoconstriction. The precise mechanism that explains protamine-mediated systemic hypotension is unknown. Four experimental protocols performed at Mayo Clinic, Rochester, MN, studied the intrinsic mechanism of protamine vasodilation. The first study reported in vitro systemic and coronary vasodilation after protamine infusion. The second in vitro study suggested that the pulmonary circulation is extensively involved in the protamine-mediated effects on endothelial function. The third study, carried out in anesthetized dogs, reported the methylene blue and nitric oxide synthase blockers neutralization of the protamine vasodilatatory effects. The fourth study suggested that protamine also causes endothelium-dependent vasodilation in heart microvessels and conductance arteries by different mechanisms including hyperpolarization. Reviewing these experimental results and our clinical experience, we suggest methylene blue as a novel approach to prevent and treat hemodynamic complications caused by the use of protamine after cardiopulmonary bypass. In the absence of prospective clinical trials, a growing body of cumulative clinical evidence suggests that methylene blue may be strongly considered as a therapeutic approach in the treatment of distributive shock.