Marcelo Bellini Dalio

Effects of acid-base imbalance on vascular reactivity

Acid-base homeostasis maintains systemic arterial pH within a narrow range. Whereas the normal range of pH for clinical laboratories is 7.35-7.45, in vivo pH is maintained within a much narrower range. In clinical and experimental settings, blood pH can vary in response to respiratory or renal impairment. This altered pH promotes changes in vascular smooth muscle tone with impact on circulation and blood pressure control. Changes in pH can be divided into those occurring in the extracellular space (pHo) and those occurring within the intracellular space (pHi), although, extracellular and intracellular compartments influence each other. Consistent with the multiple events involved in the changes in tone produced by altered pHo, including type of vascular bed, several factors and mechanisms, in addition to hydrogen ion concentration, have been suggested to be involved. The scientific literature has many reports concerning acid-base balance and endothelium function, but these concepts are not clear about acid-base disorders and their relations with the three known mechanisms of endothelium-dependent vascular reactivity: nitric oxide (NO/cGMP-dependent), prostacyclin (PGI2/cAMP-dependent) and hyperpolarization. During the last decades, many studies have been published and have given rise to confronting data on acid-base disorder and endothelial function. Therefore, the main proposal of this review is to provide a critical analysis of the state of art and incentivate researchers to develop more studies about these issues.

Ischemic pre and postconditioning in skeletal muscle injury produced by ischemia and reperfusion in rats

PURPOSE To investigate the protective effects of ischemic pre and postconditioning, as well as the association of both methods, in skeletal muscle injury produced by ischemia and reperfusion in rats. METHODS An experimental study was designed using 40 Wistar rats divided in four groups (n=10): Control - rats submitted to ischemia for 240 minutes (min) and reperfusion for 60 min; Ischemic preconditioning (Pre) - animals submitted to three cycles of clamping and releasing the aorta for five min before being submitted to the ischemia/reperfusion procedure; Ischemic postconditioning (Post) - rats submitted to three cycles of clamping and releasing the aorta for one min after the 240-minute ischemic phase; Ischemic pre and postconditioning (Pre-post) - animals submitted to the same procedures of Pre and Post groups. Skeletal muscle injury was evaluated by measuring serum levels of aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and creatine phosphokinase (CPK); and muscular levels of malondialdehyde (MDA) and glycogen. RESULTS AST levels were significantly higher in Pre and Pre-post groups (P<.01). There were no differences in LDH and CPK levels. Muscular MDA levels were similar. Glycogen levels were significantly higher in Pre and Pre-post groups (P<.01). CONCLUSIONS Both preconditioning and its association with postconditioning had a protective effect by avoiding glycogen depletion in skeletal muscle in rats submitted to ischemia and reperfusion. Association of pre and postconditioning did not show advantage compared to preconditioning alone. Postconditioning alone did not show protective effect.

Endovascular Approach for Peripheral Arterial Injuries

BACKGROUND In appropriate situations, treatment of arterial injuries with stent grafts decreases operative time, estimated blood loss, and iatrogenic complications when compared with open treatment. The purpose of this study was to describe the recent experience and outcomes of this technique in a large tertiary hospital. METHODS The medical records of 16 patients with peripheral arterial injuries were analyzed in a retrospective single-institution review. RESULTS Injuries were caused by trauma in 6 patients (38%), iatrogeny during vascular access in 6 (38%), and complications of open surgical procedures in 4 (25%). The subclavian-axillary segment was involved in 5 cases (31%), femoropopliteal artery in 5 (31%), carotid artery in 3 (19%), and iliac arteries in another 3 (19%). Clinical presentation of the injury was pseudoaneurysm in 8 cases (50%), arteriovenous fistula (AVF) in 3 (19%), bleeding in 3 (19%), and pseudoaneurysm associated with AVF in 2 (13%). All patients were hemodynamically stable at evaluation, and were treated with balloon-expanding or self-expanding stent grafts. All patients were followed up with a duplex scan, with a mean follow-up time of 17.3 months. No deaths or amputations occurred. Four patients (25%) returned with occluded stent grafts. Among them, 3 presented with mild or no symptoms. One patient was treated with open vascular bypass to treat limiting-arm symptoms. CONCLUSIONS Treating penetrating arterial injuries with stent grafts was shown to be safe and effective.

Forças mecânicas e veias safenas humanas: implicação na revascularização do miocárdio

Vascular endothelial cells are exposed to a variety of in vivo mechanical forces, specifically, shear stress for the blood flow, tensile stress from the compliance of the vessel wall and the hydrostatic pressure from containment of blood within inside the vasculature. Many authors studied hemodynamic, functional and morphological human saphenous veins alterations caused by these different forces with conflictant results. This review text was motivated with the specific aim of analyze literature data and some experimental data carried out in our laboratory. The adopted review subjects were: 1) Endothelial responses and gene regulation to shear stress; 2) Effects of the hydrostatic pressure in the endothelial cell morphology, gene expression of the endothelial cellular surface and proliferation of endothelial cells; 3) Effects of the traction on the human saphenous vein endothelium.

A prospective study of venous hemodynamics and quality of live at least five years after varicose vein stripping

PURPOSE To assess venous hemodynamics and quality of life at lest five years after varicose vein stripping. METHODS We conducted a prospective study with 39 patients (63 limbs) with primary lower limbs varicose veins. Preoperatively, all patients were subjected to clinical evaluation, duplex ultrassound, air plethysmography (APG), and CIVIQ questionnaire of quality of life. By APG, venous filling index (VFI), ejection fraction (EF), and residual volume fraction (RVF) were determined. CIVIQ addresses four domains in course of 20 questions, including states of physical, social, and psychological well-being, and pain level. Varicose veins were treated by standard venous stripping. At least five years after surgery (77.9 ± 10.9 months), patients were reassessed and had clinical examination, duplex ultrasound, APG, and CIVIQ repeated. No late follow-up data was available for 24 patients. RESULTS Preoperative and late postoperative VFI levels were similar, whereas EF (P=0.05) and RVF (P=0.01), as hemodynamic variables, significantly improved following surgery. In the late postoperative period, overall CIVIQ scores were significantly lower (P=0.005), as were scores in all four domains: pain (P=0.001), physical (P=0.007), social (P=0.008), and psychological (P= 0.05). CONCLUSION In a small prospective cohort, improvements in venous hemodynamics and in quality of life of patients submitted to standard varicose veins stripping were maintained five years after the procedure.

Expression of apoptosis in human saphenous vein grafts in restoration of blood flow through coronary bypass surgery

OBJECTIVE To investigate the possible role of apoptosis on brief distensions of human saphenous veins at different pressures. METHODS Fresh isolated grafts of human saphenous vein were assigned as control or distended (D) for fifteen seconds at 100, 200 and 300 mmHg. The degree of apoptotic caspases 3, 8, 9 and anti-apoptotic protein Bcl-2 expression were assessed by immunohistochemistry. RESULTS Fresh isolated segments of distended human saphenous veins presented similar apoptotic protein expression when compared with control veins. However, the Bcl-2 expression was significantly higher in the 300 mmHg distended segments compared with the control vein. CONCLUSION These findings show that intact segments of human saphenous veins submitted to distensions at different pressures have similar apoptotic proteins expression when compared with non-distended control veins. Therefore, brief distensions commonly performed during surgical harvesting do not trigger apoptosis, and probably are not involved on the physiopathological mechanisms that lead to graft failure.

Morphological aspects of mural thrombi deposition residual lumen route in infrarenal abdominal aorta aneurisms

PURPOSE To assess the most frequent deposition site of mural thrombi in infrarenal abdominal aorta aneurisms, as well as the route of the residual lumen. METHODS Assessment of CT scan images from 100 patients presenting asymptomatic abdominal aorta aneurism, and followed at HC-FMRP-USP. RESULTS In 53% of the cases the mural thrombus was deposited on the anterior wall; from these, in 22%, the residual lumen described a predominantly right sided route; in 22%, a left sided route; on the mid line in 5%; and crossing over the mid line in 1%. In 23%, the deposition of thrombi was concentric. In 11% it occurred on the posterior wall; from these, in 5%, the route of the residual anterior lumen was predominantly right sided; in 5%, left sided; and crossed over the mid line in 1%. In 13% complex morphological deposition patterns were found. CONCLUSION Mural thrombi formation was predominantly found on the anterior wall of the aneurismatic mass, with the route of the residual lumen projecting towards the posterior wall.

Endovascular Approach to Transplant Renal Artery Stenosis.

BACKGROUND The endovascular approach has shown high initial technical success rates, good patency rates, and minimal complications in treating transplant renal artery stenosis (TRAS). The objective of this study was to describe our experience with an endovascular approach to TRAS. MATERIAL AND METHODS We performed a retrospective single-institutional review of all kidney transplant procedures performed at our institution from September 2009 to September 2014. All consecutive cases of TRAS were included. RESULTS From a total of 183 kidney transplantations, 16 patients had TRAS. Mean time from transplantation to TRAS diagnosis was 201.8 days. Stenoses or hemodynamic significant kinkings were located at the anastomosis (7), proximal (5) and middle (4) portions of the transplant artery. All patients were treated with angioplasty and primary balloon-expanding stenting. Early technical success was 93.75% and local complication rate was 12.5%. No deaths occurred. Mean serum creatinine level dropped from 3.87 mg/dL to 2.91 mg/dL after 24 hours; 1.85 mg/dL after one month; and 1.67 mg/dL after three months (P<0.05). Mean estimated glomerular filtration rate increased from 31.60 mL/min to 39.53 mL/min after 24 hours; 50.92 mL/min after one month; and 55.05 mL/min after three months (P<0.05). Doppler ultrasound criteria normalized after the procedure. Number of classes of antihypertensive drugs was not different before and after the procedure (P=0.38). Mean follow-up time was 9.75 months. One patient had a restenosis and required surgical intervention to restore graft function. CONCLUSIONS The endovascular approach to TRAS with primary balloon-expanding stenting was safe and had a high rate of technical success. It was effective for restore and maintain the renal function in transplant kidney grafts with a low rate of restenosis.

Aneurisma de aorta abdominal justa-renal: correção endovascular combinada com derivação ilíaco-renal direita para criar colo proximal adequado

A 78-year-old man with a juxtarenal abdominal aortic aneurysm and several comorbid conditions was admitted at the emergency room in hemodynamically stable conditions. Computed tomography revealed an aneurysm measuring 6 cm in diameter beginning 28 mm below the left renal artery and 5 mm below the right renal artery. Because of the patients clinical status, a bypass from the right iliac artery to the right renal artery was performed through a retroperitoneal approach using a polytetrafluoroethylene vascular graft. Four days later, an endovascular aneurysm repair was successfully performed using an Excluder® stent-graft. Postoperative follow-up showed good left renal perfusion and no migration or endoleak. This case illustrates the effectiveness of combining open and endovascular techniques to repair juxtarenal abdominal aortic aneurysm in high-risk patients with unfavorable anatomy.

Aortogastric Fistula Due to a Penetrating Atherosclerotic Aortic Ulcer

Penetrating aortic ulcer (PAU) is an atherosclerotic lesion with ulceration that penetrates the internal elastic lamina of the aortic wall. PAUs are classified as a category of acute aortic syndrome and have a reported rupture rate of up to 38%. To our knowledge, there is no prior published report of a PAU causing an aortogastric fistula. With the goal of raising awareness of this potentially catastrophic complication, we present herein a case of a PAU that ruptured into the gastric fundus, resulting in massive bleeding. The diagnosis was confirmed by computed tomography angiography, and thoracic endovascular aortic repair was used to control bleeding. Unfortunately, the patient did not survive the severe hypovolemic shock.