Secondary S100B Protein Increase Following Brain Arteriovenous Malformation Rupture is Associated with Cerebral Infarction

Early S100B protein serum elevation is associated with poor prognosis in patients with ruptured brain arteriovenous malformations (BAVM). The purpose of this study is to determine whether a secondary elevation of S100B is associated with early complications or poor outcome in this population. This is a retrospective study of patients admitted for BAVM rupture. A secondary increase of S100B was defined as an absolute increase by 0.1 μg/L within 30 days of admission. Fisher’s and unpaired t tests followed by multivariate analysis were performed to identify markers associated with this increase. Two hundred and twenty-one ruptures met inclusion criteria. Secondary S100B protein serum elevation was found in 17.1% of ruptures and was associated with secondary infarction (p < 0.001), vasospasm-related infarction (p < 0.001), intensive care (p = 0.009), and hospital length of stay (p = 0.005), but not with early rebleeding (p = 0.07) or in-hospital mortality (p = 0.99). Secondary infarction was the only independent predictor of secondary increase of S100B (OR 9.9; 95% CI (3–35); p < 0.001). Secondary elevation of S100B protein serum levels is associated with secondary infarction in ruptured brain arteriovenous malformations.

A high red blood cell distribution width predicts failure of arteriovenous fistula

In hemodialysis patients, a native arteriovenous fistula (AVF) is the preferred form of permanent vascular access. Despite recent improvements, vascular access dysfunction remains an important cause of morbidity in these patients. In this prospective observational cohort study, we evaluated potential risk factors for native AVF dysfunction. We included 68 patients with chronic renal disease stage 5 eligible for AVF construction at the Department of General and Vascular Surgery, Central Clinical Hospital Ministry of Internal Affairs, Warsaw, Poland. Patient characteristics and biochemical parameters associated with increased risk for AVF failure were identified using Cox proportional hazards models. Vessel biopsies were analyzed for inflammatory cells and potential associations with biochemical parameters. In multivariable analysis, independent predictors of AVF dysfunction were the number of white blood cells (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.24 to 2.25; p<0.001), monocyte number (HR 0.02; 95% CI 0.00 to 0.21; p = 0.001), and red blood cell distribution width (RDW) (HR 1.44; 95% CI 1.17 to 1.78; p<0.001). RDW was the only significant factor in receiver operating characteristic curve analysis (area under the curve 0.644; CI 0.51 to 0.76; p = 0.046). RDW>16.2% was associated with a significantly reduced AVF patency frequency 24 months after surgery. Immunohistochemical analysis revealed CD45-positive cells in the artery/vein of 39% of patients and CD68-positive cells in 37%. Patients with CD68-positive cells in the vessels had significantly higher white blood cell count. We conclude that RDW, a readily available laboratory value, is a novel prognostic marker for AVF failure. Further studies are warranted to establish the mechanistic link between high RDW and AVF failure.

Surgical improvement of hepatic venous mixing to resolve systemic arterial hypoxemia associated with post-Fontan pulmonary arteriovenous fistulae

Pulmonary arteriovenous fistulae are known to develop in patients who have functional single-ventricle heart disease and interruption of the inferior vena cava with direct hepatic drainage to the heart, in which a bidirectional Glenn shunt is the only source of pulmonary blood flow. The progressive systemic arterial hypoxemia that is associated with pulmonary arteriovenous fistulae can have important clinical consequences. Baffling the hepatic venous return to the pulmonary circulation can alleviate pulmonary arteriovenous fistulae.Herein, we present the case of a 13-year-old patient with modified Fontan anatomy and pulmonary arteriovenous fistulae, in whom redirection of a previously placed hepatic venous-to-right pulmonary artery conduit was required in order to increase systemic arterial oxygen saturation. Revision of the conduit improved mixing of hepatic venous effluent with blood flow from the bidirectional Glenn shunt. Three years after this revision, the patient's oxygen saturation remained stable at 90%, and his physical activity was markedly improved. We present our rationale for selected redirection of the conduit and discuss other surgical options that can improve hypoxemia that is associated with pulmonary arteriovenous fistulae.

Simultaneous resection of liver cell adenomas and an intrahepatic portosystemic venous shunt with elevation of serum PIVKA-II level

A 27-year-old woman with no history of liver disease or oral contraceptive use presented with sudden abdominal pain. Laboratory data showed mild liver dysfunction with jaundice. Computed tomography and angiography revealed centrally located large liver cell adenomas (LCAs) and an intrahepatic portosystemic venous shunt (IHPSS) in the left lobe. The serum des-gamma-carboxy prothrombin (known as "protein induced by a lack of vitamin K or antagonist II," PIVKA-II) level was extremely high (6,647 mAU/ml), indicating malignant transformation of the tumors. Under the diagnosis of LCAs and IHPSS, the patient underwent simultaneous resection of the four liver tumors and portovenous shunt, and the hepatic vascular abnormality was resolved. The pathological diagnosis was LCAs without hepatocellular carcinoma. Immunohistochemical analysis with an anti-PIVKA-II monoclonal antibody showed positive staining of the adenoma cells. This case shows that LCA without malignant transformation can produce PIVKA-II, leading to high serum levels of PIVKA-II. Simultaneous resection of multiple tumors and closure of the portosystemic shunt are strongly recommended in a patient with LCA associated with IHPSS.

Case report: Recurrent heart failure with preserved ejection fraction but markedly elevated BNP in a 51-year-old female on hemodialysis with oversized AV fistula

We hereby report a case that appeared to have had recurrent clinical heart failure secondary to high-output state due to oversized arteriovenous fistula. Patient started to have dyspnea on exertion approximately 4 months after the creation of the fistula, and subsequently had two episodes of heart failure exacerbation. On both occasions, she had normal left ventricular systolic function as demonstrated by echocardiogram. The shunt was estimated to be as large as 1.9 L/min. B-type natriuretic peptide (BNP) levels were markedly elevated. To our knowledge, this is the first case in which BNP level was reported and used in the diagnosis of high-output heart failure.

Effect of surgical banding of a high-flow fistula on access flow and cardiac output: Intraoperative and long-term measurements

Creation of either a natural arteriovenous graft or a fistula as a vascular access to support long-term hemodialysis can lead to "high-output" cardiac failure. The authors describe a patient who underwent surgical banding of an upper arm arteriovenous fistula. Access flow and cardiac output were measured not only pre- and postoperatively but also intraoperatively using a modified Swan Ganz catheter, originally developed to measure access flows during radiologic procedures. Banding resulted in a significant decrease in access flow and cardiac output, which was sustained for up to 1 year postoperatively.

Effects of Superselective Embolization for Renal Vascular Injuries on Renal Parenchyma and Function

AIM

Our objective was to evaluate the outcome of superselective embolization used for treatment of renal vascular injuries on renal parenchyma and renal function.

MATERIALS AND METHODS

Between January 1999 and December 2001, 6 consecutive patients (five males, one female, mean age 45 years) underwent embolization to treat bleeding from renal vascular injuries, resulting from iatrogenic interventions (4) and blunt abdominal trauma (2). Five patients had increased serum creatinine. Angiography depicted a pseudoaneurysm (PA) in three, PA with arteriovenous fistula (AVF) in one, and active extravasation in two patients. Superselective catheterization was achieved using a 5-F catheter in three, and coaxial microcatheter in the remaining three cases. All lesions were successfully embolized with 0.035" or 0.018" coils.

RESULTS

Bleeding was ceased in all patients and did not recur. Mean post-embolization parenchymal ischemic area was 11.7% (range: 0-30%). Imaging follow-up (mean: 12 months, range: 5-23) showed that mean parenchymal infarcted area was 6% (range: 0-15%). Serum creatinine level was normal in all patients one week after the procedure and at the latest follow-up.

CONCLUSION

Superselective embolization resulted in permanent cessation of bleeding. Serious parenchymal infarction was prevented and serum creatinine level returned to the pre-bleeding values. Embolization should be considered as the treatment of choice in this patient population.

A case of pregnancy with a history of paradoxical brain embolism

Brain embolisms in younger persons are rare but are often caused by a paradoxical embolism, the embolic entry of a venous thrombus into the systemic circulation through a right-to-left shunt. A 27-year-old pregnant woman presented with hemiplegia that had been treated with an antiplatelet agent since the occurrence of a paradoxical brain embolism via the pulmonary arteriovenous fistula. A tendency of hypercoagulation is generally observed during pregnancy, so a patient with this condition has a strong risk factor for venous thromboembolism during pregnancy and even more so for arterial thromboembolism under the intense strain of labor, which is much stronger than that of the Valsalva maneuver. This case had been controlled well with an antiplatelet agent and an anticoagulant while the levels of coagulation and fibrinolytic factors were monitored and was followed by a successful pregnancy outcome.

Dynamic venous access pressure ratio test for hemodialysis access monitoring

BACKGROUND

Early recognition of arteriovenous graft (AVG) dysfunction in hemodialysis (HD) patients followed by prompt corrective procedures reduces AVG thrombosis rates and lengthens access survival. We developed a method to prospectively monitor AVGs that uses an algorithm to calculate venous access pressure (VAP) during HD from the venous drip chamber pressure (VDP).

METHODS

Sham HD with blood was performed using standard blood tubing and a 1-in. 15-G needle. The pressure needed to overcome circuit resistance at an intra-access pressure of zero (VDP(0)) was recorded at blood flow rates (Q(b)s) from 0 to 600 mL/min and hematocrits varied in steps from 38.4% to 18.2%. An equation for VDP(0) was developed. VAP in patients was calculated as VAP = VDP - VDP(0). VAP ratio (VAPR) was defined as VAP/mean arterial pressure (MAP). VAPR was calculated only if MAP was greater than 75 mm Hg, Q(b) was greater than 200 mL/min, and VDP was greater than 20 mm Hg. A positive VAPR test (VAPRT) result was defined as three consecutive treatments with VAPR exceeding 0.55 during a given month. Sensitivity and specificity of VAPRT to predict a graft event, defined by AVG occlusion or requirement for angioplasty, were calculated.

RESULTS

During a 3-month interval, 120 HD patients with AVGs underwent 359 VAPRTs while access outcomes were monitored for 6 months. After 3 months, sensitivity and specificity for detection of a graft event were 70% +/- 8% and 88% +/- 2% and increased to 74% +/- 5% and 92% +/- 3% at 6 months, respectively.

CONCLUSION

The VAPRT is a valuable tool to prospectively monitor for adverse AVG events.

Homocysteine and vascular access thrombosis in hemodialysis patients

BACKGROUND

Vascular access remains the Achilles' heel of successful hemodialysis, and thrombosis is the leading cause of vascular access failure. Hyperhomocystinemia is common in hemodialysis patients and is associated with venous and arterial thrombosis in patients without end-stage renal disease.

SUBJECTS AND METHODS

In the study, 65 hemodialysis patients with native arteriovenous fistula were included. Two groups of patients were defined: group A including 45 patients with their vascular access either never or only once thrombosed, and group B including 20 patients with two or more thromboses of their vascular access. We determined serum concentrations of total homocysteine (immunoassay, Abbott) in our patients.

RESULTS

In 63 (96.9%) patients, hyperhomocystinemia was presented. There was no statistically significant difference between group A and B regarding age, gender and duration of hemodialysis treatment. Total homocysteine concentrations were higher in group A (42.1 +/- 18.6 micromol/l) than in group B (36.1 +/- 18.1 micromol/l) patients but the difference was small and not statistically significant.

CONCLUSION

We found no significant differences in total homocysteine concentrations between group A (thrombosis non-prone) and group B (thrombosis prone) patients. Our results suggest that thrombosis of native arteriovenous fistulas may not be caused by hyperhomocystinemia in these patients.

[Successful thoracoscopic resection of pulmonary arterio-venous fistula]

A 65-year-old female was admitted for further examination of an abnormal shadow on a chest roentgenogram. Chest computed tomography revealed a lobular nodule with blood vessels, which was diagnosed as pulmonary arterio-venous fistula (PAVF). Thoracoscopic resection was performed under general anesthesia. The fistula was situated directly below the pleura of the left lower lobe. Partial resection of the left lung including the PAVF was performed with an autosuture device dedicated to endoscopic surgery (Endo GIA II). The patient was discharged from our hospital 3 days after surgery without major complications. Mild hypoxemia was corrected after the surgery. Thoracoscopic resection is considered to be safe and useful for a solitary PAVF existing a peripheral field of the lung.

Pulmonary arteriovenous fistulas: Mayo Clinic experience, 1982-1997

OBJECTIVE

To describe the results of analysis of clinical, physiologic, diagnostic, and therapeutic aspects and complications in patients with pulmonary arteriovenous fistulas (PAVFs).

PATIENTS AND METHODS

Retrospective review of medical records of all patients with the diagnosis of PAVF evaluated at Mayo Clinic Rochester from 1982 through 1997. Demographic characteristics, presence or absence of hereditary hemorrhagic telangiectasia, clinical features, and results of imaging studies and blood gas analyses, treatments, and complications related to PAVFs were reviewed.

RESULTS

Among the 93 patients, 44 were male and 49 female. The mean age at the time of evaluation was 40 years (range, 5-83 years). Fifteen patients (16%) were asymptomatic. History of hereditary hemorrhagic telangiectasia was present in 52 patients (56%). Notable clinical findings included epistaxis in 46 (49%), hemoptysis in 14 (15%), cyanosis in 27 (29%), clubbing in 18 (19%), dyspnea in 53 (57%), and pulmonary bruits/murmurs in 32 (34%). Chest x-ray films with or without tomograms showed abnormal findings in 87 (94%), of which 68 (73%) suggested PAVF. Polycythemia was detected in 12 (13%). Pretherapy arterial PO2 measured on room air averaged 56 mm Hg (range, 32-95 mm Hg), and the posttherapy PO2 averaged 77 mm Hg (range, 46-110 mm Hg). Echocardiography with indocyanine green dye was diagnostic of extracardiac right-to-left shunt in 26 (90%) of 29 patients tested. Diagnostic studies revealed single lesions in 32 patients (34%) and multiple lesions in 61 (66%). The most prominent complications of the disease were neurologic events in 34 patients (37%). These complications included transient ischemic attacks, hemiplegia, brain abscesses, and seizures. Surgical resection alone was carried out in 18 patients (19%), embolization therapy alone in 41 (44%), and both therapies in 7 (8%). The 48 patients treated with embolization required 78 embolization sessions with more than 200 lesions occluded. Complications of treatment included postembolization hemothorax in 1 patient and right-sided hemiparesis in another patient. Follow-up disclosed that 1 patient died from PAVF-related complications.

CONCLUSIONS

Among our patients with PAVFs, hereditary hemorrhagic telangiectasia was observed in more than half and neurologic complications in more than one third. Because of the considerable risk of neurologic and other complications, definitive treatment should be considered in patients with PAVFs. Embolization is currently the preferred treatment in most patients. Frequent follow-up of treated patients is necessary because PAVFs tend to increase both in number and in size over time.

Acute renal impairment due to a primary aortocaval fistula is normalised after a successful operation

OBJECTIVES

To study renal function in patients with aortocaval fistula, before and after surgery.

DESIGN

Retrospective study.

MATERIAL AND METHODS

During the last 22 years nine male patients (median age 67, age range 50-72) with spontaneous aortocaval fistula in combination with AAA were operated upon. This constitutes 4% of the patients with ruptured AAA and 1.5% of all patients with AAA.

RESULTS

A preoperative diagnosis of aortocaval fistula was established in three of the nine cases. The medium duration of symptoms prior to surgery was 5 days (range 4 h-14 days). The fistula was combined with an extravasating ruptured AAA in only three patients. Seven of the patients had acute renal insufficiency, with creatinine levels of in median 292 mumol (IQR 218-342). Creatinine declined to 172 mumol/l (IQR 170-313) on the fifth postoperative day in uncomplicated cases and to 86 mumol at discharge. One patient died due to multi-organ failure, whereas the other left hospital well and alive with normal renal function.

CONCLUSION

Acute preoperative renal insufficiency due to an aortocaval fistula in patients with AAA is often due to venous congestion, and is normalised after successful surgery.

[Arteriovenous fistula of the lung: a rare cause of erythrocytosis]

Various chronic pulmonary diseases can cause hypoxia mediated erythrocytosis. We report on a 46 year old male patient presenting with erythrocytosis, in whom a pulmonary arteriovenous fistula on the basis of a vascular malformation was identified as a rare cause of hypoxic erythrocytosis. Thus, congenital pulmonary vascular malformations can become clinically manifest in advanced age.

Diagnosis of traumatic carotid-cavernous sinus fistula by monitoring venous oxygen saturation in the jugular bulb: report of two cases

OBJECTIVE AND IMPORTANCE

A traumatic carotid-cavernous sinus fistula (CCF) is rarely diagnosed early and may sometimes be missed until clinical signs and symptoms appear. The continuous monitoring of cerebral venous oxygen saturation may reveal the presence of a CCF by means of a fiberoptic catheter that records very high oxygen saturation values when positioned in the jugular bulb.

CLINICAL PRESENTATION

We report two cases of early diagnosis of CCFs unexpectedly revealed by monitoring the jugular bulb for venous oxygen saturation values that approximated arterial saturation values. One case was diagnosed on Day 3 after admission, and the other was diagnosed shortly after cannulation of the ipsilateral jugular bulb.

INTERVENTION

Confirmation of the diagnosis of CCF was obtained by angiography. Intravascular treatment was performed in one case.

CONCLUSION

These cases add another diagnostic role to cerebral venous oxygen saturation monitoring. When high cerebral venous oxygen saturation values rapidly or abruptly reach arterial oxygen saturation, the presence of a CCF must be considered and confirmed by arterial angiography.

Role of neutral endopeptidase 24.11 in AV fistular rat model of heart failure

OBJECTIVE

The aortovenocaval fistular (AVF) rat represents a model of heart failure caused by increased cardiac volume overload and reduced renal function. Both circulating vasoconstrictors like the renin-angiotensin-aldosterone system and vasodilators like atrial and brain natriuretic peptides (ANP and BNP) are activated in this animal model of heart failure. In addition, neutral endopeptidase 24.11 (NEP) in plasma and urine is elevated in AVF rats. In the present investigation we examined the renal and hormonal effects of the NEP inhibitor, ecadotril, in acute and chronic studies in rats with an aortovenocaval fistula (AVF).

METHODS

Sprague Dawley rats (350-430 g) were prepared by introducing a shunt between abdominal aorta and the vena cava.

RESULTS

Acute administration of the neutral endopeptidase inhibitor, ecadotril (30 mg/kg p.o.), significantly improved the reduced renal excretion of sodium in AVF rats (83 +/- 10 to 145 +/- 14 mumol/kg/h, P < 0.01) but had no significant effect in sham-operated rats. However, neutral endopeptidase activity in urine was significantly decreased after ecadotril in both groups. Plasma ANP was increased after ecadotril only in AVF rats (275 +/- 83 to 748 +/- 187 pg/ml, P < 0.05), whereas the increase in plasma BNP was not statistically significant. After 4 weeks of observation the ANP and BNP plasma levels, renin activity (PRA), angiotensin I, and neutral endopeptidase activity were significantly higher in AVF rats than in sham-operated rats. Four weeks on ecadotril (30 mg/kg p.o., b.i.d.) increased plasma ANP (245 +/- 48 as opposed to 450 +/- 77 pg/ml, P < 0.05) and decreased PRA (11.3 +/- 1.5 as opposed to 6.8 +/- 1.2 ng/ml/h, P < 0.005) in AVF rats. Plasma NEP activity was inhibited in both groups. Ventricle weight was significantly higher in AVF rats than in sham-operated controls, and ecadotril treatment over 4 weeks decreased ventricular hypertrophy to a slight extent.

CONCLUSION

These results indicate that in the AVF rat model of heart failure the neutral endopeptidase inhibitor, ecadotril, improves the reduced kidney function in AVF rats by raising natriuretic peptides in plasma and probably in urine. NEP inhibition with ecadotril could therefore offer useful therapeutic possibilities in the treatment of heart failure.

Early discovery of a traumatic carotid-cavernous sinus fistula by jugular venous oxygen saturation monitoring. Case report

This report describes the early diagnosis, due to an acute increase of jugular venous oxygen saturation occurring 20 hours after trauma, of a traumatic carotid-cavernous sinus fistula after severe head injury. Hyperemia in severe head injury should be treated only after an intracerebral arteriovenous communication has been excluded.

Transcranial cerebral oximetry and carotid cavernous fistula occlusion. Technical note

Different methods have been used in the evaluation and monitoring of the cerebral oxygen supply during neuro-interventional therapies. Attenuation of near-infrared light by the chromophores oxyhemoglobin and deoxyhemoglobin have shown to be useful in the study of the cellular oxygen metabolism and oxygen delivery to the brain. Transcranial cerebral oximetry (TCCO) has the advantage of providing real-time information regarding regional brain oxygen saturation (rSO2) by using wavelengths in the near-infrared range. We present a patient with a carotid cavernous fistula who underwent balloon occlusion and concurrent continuous TCCO monitoring. TCCO was found to be a useful tool providing immediate rSO2 values during the angiographic and interventional procedures. Initial balloon occlusion of a carotid cavernous fistula resulted in partial occlusion of the internal carotid artery lumen causing an immediate decrease in rSO2 which correlated with angiographic findings. Subsequent reocclusion of the fistula produced a slower and smaller degree of decrease in rSO2 with clinical improvement in the patient. Changes in rSO2 were detected before any adverse clinical event was observed. TCCO was reliable, safe, sensitive, and provided a real-time assessment tool for the monitoring of brain oxygen supply in a patient undergoing a neuroendovascular procedure.

The ultrastructure of arteries proximal to chronic experimental carotid-jugular fistulae in rabbits

The afferent arteries from 11 normocholesterolemic rabbits with carotid-jugular arteriovenous fistulae ranging in duration from 107 to 718 days were examined by transmission electron microscopy to determine long term effects of an arteriovenous shunt on the afferent artery. Extensive tears and fragmentation of the internal elastic lamina of the elastic common carotid arteries were observed in all animals. Fragmentation and loss of elastic tissue as well as loss of muscle in the media accompanied progressive mural atrophy and tortuosity. Close to the fistula and in regions of tortuosity, fibromusculoelastic intimal proliferation was superimposed on the atrophic medial changes. The accumulation of matrix vesicles (cell debris), bizarre shaped smooth muscle cells, irregularly thickened multilaminated and reticulated basement membrane material beneath the endothelium and about smooth muscle cells, and abnormal shaped collagen fibrils were observed in the intima. Lipid was frequently found in the extracellular matrix and within smooth muscle cells while monocytes and lipid-laden macrophages were a feature of the more advanced intimal changes. These experiments confirm that in the absence of hypercholesterolemia the hydraulic stresses associated with an arteriovenous shunt cause severe mural atrophy and proliferative changes in the intima similar in nature to those of atherosclerosis.

Flow velocity and pressure measurements in spinal dural arteriovenous fistulas

During ten operations for spinal dural arterio-venous fistulas (AVF), intraoperative measurement of flow velocity and intravascular pressure was performed. Flow velocities were recorded using a miniaturized Doppler probe. Intravascular pressure changes in the draining veins before and after AVF removal was measured with small needles. Varying the pCO2 between 20 mm Hg and 60 mm Hg, the flow velocities in arteries supplying the spinal cord were investigated so that the vasomotoric reactivity of the peripheral vessel wall in cord tissue was investigated before and after AVF occlusion. The flow velocities in dural AVF feeders were not as high as those known from cerebral angioma feeders. In addition, they often showed lowered end-diastolic flow velocity as a sign of increased vascular resistance, thus proving impaired venous outflow from the spinal canal. After excision of the local fistula, the vessels supplying and draining the spinal cord showed improved circulation. In the former recipient veins, no further flow could be recorded. The venous pressure in dural AVF was about 70% of the systemic arterial pressure. Fistulas presenting a high shunt volume on angiography showed only moderately increased venous pressure and a more pronounced pressure drop after fistula occlusion as compared with low-volume fistulas. The CO2 reactivity of vessels supplying the spinal cord was normal before and after AFV removal.

Arteriovenous shunting, hemodynamic changes, and renal sodium retention in liver cirrhosis

BACKGROUND

Arterial vasodilation has been postulated to initiate sodium retention in cirrhosis. This work was designed to analyze whether arteriovenous shunting underlies vasodilation and influences renal function in cirrhosis.

METHODS

The femoral arteriovenous difference in oxygen content (Ca-VO2) was measured in 10 healthy subjects (control group) and 31 cirrhotic patients: 9 without ascites (group 1), 10 with ascites and a urinary sodium excretion rate (UNaV) of > 10 mEq/24 h (group 2), and 12 with ascites and UNaV of < or = 10 mEq/24 h (group 3). In 8 subjects from each group, femoral blood flow and the cardiac output were determined by duplex-Doppler ultrasonography. In 9 cases arteriovenous shunting in the femoral territory was estimated using 30 +/- 5-microns radiolabeled microspheres.

RESULTS

Ca-VO2 was lower in group 3 than in controls or group 1. Ca-VO2 correlated inversely with femoral blood flow, plasma renin activity, plasma aldosterone concentration, and degree of shunting measured by microspheres. Ca-VO2 correlated directly with systemic vascular resistance and prothrombin index.

CONCLUSIONS

In decompensated cirrhotic patients, there is an increased arteriovenous shunt for oxygen in the lower extremities that is associated with increased arterial blood flow, decreased systemic vascular resistance, and worsening of liver function. This shunt is due partly to opening of arteriovenous precapillary connections.

Postoperative improvement in blood lactate threshold during exercise in a patient with pulmonary arteriovenous fistula

A 13-year-old female patient with a pulmonary arteriovenous fistula (PAVF) of 24 percent shunt fraction (SF) underwent resection of segments 8 and 9 of the left lower lobe. Three months after the operation, the shunt became insignificant and PaO2 was normalized. In terms of the maximum work rate, maximum VO2 and the VO2-blood lactate relationship, this patient showed a remarkable postoperative improvement in the exercise capacity.

The atrial natriuretic factor hormonal system in the regulation of sodium excretion in dogs with experimental heart failure

In response to a meat meal containing 125 mEq of sodium, conscious dogs (n = 5) with an arteriovenous (AV) fistula and chronic compensated heart failure exhibited temporally related increases in postprandial plasma immunoreactive atrial natriuretic factor (iANF), right atrial pressure, and sodium excretion. In separate experiments, two weeks of dietary sodium restriction produced similar marked stimulation of renin and aldosterone both in normal dogs (n = 5), and in AV fistula dogs (n = 5) with chronic high circulating levels of ANF. Plasma iANF did not change (P greater than .05) in either group. These results suggest that the ANF system is involved in the postprandial regulation of sodium excretion in the AV fistula dogs with compensated heart failure. In the postabsorptive state, however, the activity of the renin-aldosterone axis is closely related to dietary sodium intake and appears to function independently of the ANF system for the prevention of sodium loss.

The role of arteriovenous shunts in the pathogenesis of varicose veins

Varicose veins and venous insufficiency are causes of significant morbidity. In North America 10% to 17% of the adult population is affected, an incidence 10 times that of arterial disease. Despite this, origin and mechanism of disease remain obscure. This study was designed to illustrate the presence of patent arteriovenous shunts in the varicosed limb and to assess their role. Twenty-eight women and twenty-one men with primary varicose veins were studied. Thirty-six men and seven women without venous disease served as a control group. Blood samples were collected from an arm vein and a limb varicosity in the study group along with an arterial blood sample. Blood samples were also drawn from an arm vein and the femoral vein in the control group along with an arterial blood sample. Venous partial oxygen pressure (PVO2) and hemoglobin saturation (HbSat) were measured and venous oxygen content (CVO2) calculated. Mean values were then obtained and statistical comparisons made between each group. A statistically significant increase (p less than 0.001) in all three parameters--PVO2, HbSat, and CVO2--was demonstrated in the patients' limbs with varicose veins, consistent with a functioning arteriovenous shunt.

Hypertension and post-traumatic renal arteriovenous fistula: demonstration of unilaterally elevated renin secretion

Ipsilateral elevation and contralateral suppression of renin secretion have been established in a patient with a post-traumatic renal arteriovenous fistula associated with diastolic hypertension. This finding is rare because of the dilutional effect of arterial blood shunted in the renal vein. Increased renin secretion in this instance supports the proposed mechanism of diastolic hypertension with renal arteriovenous fistula.

Plasma renin in chronic experimental heart failure and during renal sodium "escape" from mineralocorticoids

A striking increase in the plasma renin level occurred in dogs with low output right heart failure secondary to tricuspid insufficiency and pulmonic stenosis and in three of five animals with high output failure produced by a large arteriovenous fistula. When dogs with a small arteriovenous fistula were given daily injections of DOCA, the renal sodium "escape" phenomenon occurred. In these animals, the level of plasma renin was suppressed during DOCA administration both during the initial period of sodium retention and also later when sodium balance was normal or negative. In contrast, when dogs with a larger arteriovenous fistula but without evidence of cardiac failure were given DOCA, they retained sodium and developed signs of congestive heart failure. However, in these animals with congestion and ascites, in contrast to the dogs that developed spontaneous high output failure, the plasma renin was low. Renin-substrate was unaltered in all of the experimental situations studied except for the decrease observed in dogs with low output right heart failure. In these animals, it seems likely that decreased renin-substrate was secondary to hepatic congestion and liver damage. The renin-angiotensin system does not seem to be related to the "escape" phenomenon, and renin does not appear to be the factor that makes the kidney unusually responsive to mineralocorticoids. Thus, in experimental heart failure the renin-angiotensin system was activated, but in the congestive syndrome produced by DOCA the plasma renin level was suppressed.