Reversal of pulmonary hypertension after ligation of a brachiocephalic arteriovenous fistula

Incidence, Clinical Correlates, and Outcomes of Pulmonary Hypertension After Kidney Transplantation: Analysis of Linked US Registry and Medicare Billing Claims

BACKGROUND

The incidence, risks, and outcomes associated with pulmonary hypertension (P-HTN) in the kidney transplant (KTx) population are not well described.

METHODS

We linked US transplant registry data with Medicare claims (2006-2016) to investigate P-HTN diagnoses among Medicare-insured KTx recipients (N = 35 512) using billing claims. Cox regression was applied to identify independent correlates and outcomes of P-HTN (adjusted hazard ratio [aHR] 95%LCLaHR95%UCL) and to examine P-HTN diagnoses as time-dependent mortality predictors.

RESULTS

Overall, 8.2% of recipients had a diagnostic code for P-HTN within 2 y preceding transplant. By 3 y posttransplant, P-HTN was diagnosed in 10.310.6%11.0 of the study cohort. After adjustment, posttransplant P-HTN was more likely in KTx recipients who were older (age ≥60 versus 18-30 y a HR, 1.912.403.01) or female (aHR, 1.151.241.34), who had pretransplant P-HTN (aHR, 4.384.795.24), coronary artery disease (aHR, 1.051.151.27), valvular heart disease (aHR, 1.221.321.43), peripheral vascular disease (aHR, 1.051.181.33), chronic pulmonary disease (aHR, 1.201.311.43), obstructive sleep apnea (aHR, 1.151.281.43), longer dialysis duration, pretransplant hemodialysis (aHR, 1.171.371.59), or who underwent transplant in the more recent era (2012-2016 versus 2006-2011: aHR, 1.291.391.51). Posttransplant P-HTN was associated with >2.5-fold increased risk of mortality (aHR, 2.572.843.14) and all-cause graft failure (aHR, 2.422.642.88) within 3 y posttransplant. Outcome associations of newly diagnosed posttransplant P-HTN were similar.

CONCLUSIONS

Posttransplant P-HTN is diagnosed in 1 in 10 KTx recipients and is associated with an increased risk of death and graft failure. Future research is needed to refine diagnostic, classification, and management strategies to improve outcomes in KTx recipients who develop P-HTN.

Post-Transplant Cardiovascular Disease

Cardiovascular disease remains a leading cause of death and morbidity in kidney transplant recipients and a common reason for post-transplant hospitalization. Several traditional and nontraditional cardiovascular risk factors exist, and many of them present pretransplant and worsened, in part, due to the addition of immunosuppression post-transplant. We discuss optimal strategies for identification and treatment of these risk factors, including the emerging role of sodium-glucose cotransporter 2 inhibitors in post-transplant diabetes and cardiovascular disease. We present common types of cardiovascular disease observed after kidney transplant, including coronary artery disease, heart failure, pulmonary hypertension, arrhythmia, and valvular disease. We also discuss screening, treatment, and prevention of post-transplant cardiac disease. We highlight areas of future research, including the need for goals and best medications for risk factors, the role of biomarkers, and the role of screening and intervention.

Kidney transplantation in valvular heart disease and pulmonary hypertension: Consensus in waiting

Kidney transplantation induces a lesser anesthetic, surgical, and physiological alterations than other solid organ transplantation. Concomitant valvular pathologies expose these patients to poor postoperative outcome. There is a critical gap in knowledge and lack of coherence in the guidelines related to the management in patients with end-stage renal disease with valvular heart disease. The individualized diagnostic and management plan should be based on the assessment of perioperative outcomes. Similarly, pulmonary hypertension in end-stage renal disease poses a unique challenge, it can manifest in isolation or may be associated with other cardiac lesions, namely left-sided valvular heart disease and left ventricular systolic and diastolic dysfunction. Quantification and stratification according to etiology are needed in pulmonary hypertension to ensure an adequate management plan to minimize the adverse perioperative outcomes. Lack of randomized controlled trials has imposed hindrance in proposing a unified approach to clinical decision-making in these scenarios. In this review, we have described the magnitude of the problems, pathophysiologic interactions, impact on clinical outcomes and have also proposed a management algorithm for both the scenarios.

Prophylactic Ligature of AV Fistula Prevents High Output Heart Failure after Kidney Transplantation

BACKGROUND

Arteriovenous (AV) fistulas are considered the gold standard for ensuring safe and long-term vascular access in patients with haemodialysis-dependent end-stage renal disease. However, previous studies demonstrated that high-flow AV fistulas might add additional cardiovascular burden in the post-transplant setting, leading to frequent fistula closure in this population. Currently, there is no consensus regarding management of high-flow fistulas in post-transplant patients with stable kidney function. The present randomized controlled trial examines the effect of prophylactic AV fistula closure on high-output heart failure.

METHODS

Twenty-eight kidney transplant patients with stable graft function, absence of pre-existing severe cardiac failure, and brachial arterial flow rate of at least 1,500 mL/min were recruited and randomized in a 1:1 ratio to an intervention and control group, respectively. The intervention group was subject to immediate fistula ligature. Patients within the control group were referred to fistula ligature only if the main study endpoint high-output heart failure was reached. The latter was defined by the presence of at least 1 clinical sign (i.e., worsening NYHA score) and at least 2 of the following echocardiographic parameters: diameter of right atrium (major) >53 mm, right atrium (minor) >44 mm, inferior vena cava ≥21 mm, right pulmonary artery >20 mm, TAPSE <16 mm, systolic pulmonal artery pressure >40 mm Hg, and/or left ventricular eccentricity index <1. During a 24-month follow-up period, quarterly measurements of kidney function, NT-proBNP, and lactate dehydrogenase as well as a biannual echocardiographic check-up were performed.

RESULTS

High-output heart failure attributable to high-flow fistula was reported in 5 of 13 control patients (38.5%), whereas no patient in the intervention group presented with clinical and echocardiographic signs of high-output heart failure during the follow-up period. Thus, prophylactic ligature of high-flow fistulas avoided high-output heart failure in our patient population (p = 0.013). Three patients in the control group, however, had to undergo fistula ligature due to aneurysm formation (n = 2) and steal phenomenon (n = 1). Median NT-proBNP levels decreased from 317 ng/L pre-ligature to 223 ng/L post-ligature (p = 0.003). Serum creatinine levels did not significantly differ before and after AV fistula ligature (1.69 vs. 1.60 mg/dL, respectively, p = 0.059). Improvement of echocardiographic findings (e.g., a decrease in systolic pulmonary arterial pressure) was found in 7 of 8 ligature patients but did not reach statistical significance.

CONCLUSION

Prophylactic ligature of high-flow AV fistulas after kidney transplantation can avoid high-output heart failure, and a more liberal approach to close AV fistulas might be justified.

Pulmonary Hypertension in Various Stages of Chronic Kidney Disease in Indian Patients

The prevalence of pulmonary hypertension (PH) in chronic kidney disease (CKD) in Indian patients has been evaluated in this study. In addition, association of PH with CKD etiology, its prevalence in various CKD stages, correlation between the severity of PH with CKD duration, various related biochemical parameters, and their relation to PH in CKD patients were analyzed. This cross-sectional and prospective study included 200 CKD patients. Detailed history and clinical examination were recorded. Hemoglobin, blood urea nitrogen (BUN), serum creatinine, albumin, and calcium-phosphorus product were recorded. Pulmonary function test was evaluated and two-dimensional echo was done 4 hours post dialysis. The prevalence of PH in CKD patients was 60.5%, with mean pulmonary artery systolic pressure (PASP) of 38.52 ± 7.32 mmHg. The mean age of those with PH was 47.85 ± 13.09 years. PH was more common in males (p = 0.03). The prevalence of PH increased as CKD stage advanced (p < 0.001). Diabetes and hypertension had a strong association with PH (p < 0.001). The prevalence (p = 0.003) and severity (p = 0.011) of PH increased with increase in CKD duration. In patients on hemodialysis (HD), the prevalence (p < 0.001) and severity (p = 0.022) of PH was significant compared to those on conservative treatment. The prevalence (p < 0.001) and severity (p < 0.001) of PH significantly increased as duration of HD increased. The prevalence of PH was significantly higher in patients with arteriovenous fistula (p = 0.002). Serum creatinine (p = 0.02) and serum calcium-phosphorus product (p < 0.001) were significantly higher in patients with PH. The prevalence of PH in CKD patients was 60.5%. There was a positive correlation between PH and duration of CKD, duration of HD, BUN, serum creatinine, and serum calcium-phosphorus product.

Effects of the Arteriovenous Fistula on Pulmonary Artery Pressure and Cardiac Output in Patients with Chronic Renal Failure

Introduction

Access to the vascular system is necessary in patients with chronic renal failure planned to undergo dialysis. One of the complications of end-stage renal disease patients is pulmonary hypertension (PHT). Temporary arterio-venous access closure and successful kidney transplantation causes a significant fall in cardiac output and pulmonary artery pressure (PAP), indicating the possibility that excessive pulmonary blood flow is involved in the pathogenesis of the disease. We attempted to study the relationship of PHT with arteriovenous fistula (AVF) creation, as well as to assess the relationship between AVF flow and fistula characteristics.

Methods

Fifty patients were included in the study. Echocardiography was used to evaluate systolic PAP, cardiac output (CO), and ejection fraction (EF) before creating the AVF. After a follow-up interval of at least 6 months, a second echocardiographic assessment and a Doppler sonographic assessment of their fistula flow were carried out. Complete data were available for 34 patients.

Results

Study data were collected from 34 patients, 28 males and 6 females with a mean age of 52 yrs ranging from 15–78 yrs. The data showed a statistically significant positive correlation between fistula flow and PAP2 and PAP changes (p<0.05). Mean fistula flow was 1322 ml/min in patients without PHt and 2750 ml/min in patients with PHT. this difference (1428 ml/ min) was statistically significant (p=0.03). We found a significant negative correlation between PAP1 and EF1 and PAP2 and EF2 (p<0.05). In addition, the mean EF2 in patients without PHT was 57% in contrast to 46% in patients with PHT. Mean fistula flow in radial fistulae (mean=422 ml/min, range: 370–474 ml/min) was significantly less than brachial fistulae (mean=1463 ml, range: 270–3300 ml/min) (p=0.03). Mean systolic PAP2 of 14.8 mmHg in transplanted patients was 5.9 mmHg less than those who were not transplanted (20.7 mmHg). Diabetes was the most common cause of renal failure and diabetics had a significant reduction in their EF (15.5%) compared with non-diabetic patients (1% reduction) (p=0.016).

Conclusion

Fistula flow, PAP and EF of all patients should be checked at least 6 months after fistula creation. Patients with higher fistula flow rates and patients with diabetes mellitus need to be more closely observed. In addition, elderly patients with significant cardiac and other comorbidities may be more prone to develop symptoms after AVF creation

Controversies in the management of the haemodialysis-related arteriovenous fistula following kidney transplantation

Arteriovenous fistula (AVF) is regarded as the best vascular access for chronic haemodialysis (HD). Still, AVF inherently causes significant haemodynamic changes. Although the necessity for vascular access despite its putative cardiovascular complications favours AVF creation in patients under chronic HD, one may question whether sustaining a functional AVF after successful kidney transplantation extends the haemodynamic threat. Small prospective series suggest that AVF ligation causes rapid and sustained reduction in left ventricular hypertrophy. Still, the benefits of such a cardiac remodelling in long-terms of cardiovascular morbi-mortality still need to be proven. Furthermore, the elevation of diastolic blood pressure and arterial stiffness caused by AVF ligation may blunt the expected cardio-protection. Finally, the closure of a functioning AVF may accelerate the decline of kidney graft function. As a whole, the current management of a functioning AVF in kidney transplant recipients remains controversial and does not rely on strong evidence-based data. The individual risk of graft dysfunction and a return to chronic HD also needs to be balanced. Careful pre-operative functional assessments, including cardio-pulmonary testing and estimated glomerular filtration rate slope estimation, may help better selection of who might benefit the most from AVF closure. Large-scale prospective, ideally multi-centric, trials are essentially needed.

High hemodialysis vascular access flow and impaired right ventricular function in chronic hemodialysis patients

There are limited data showing right ventricular preload increase due to high-flow arteriovenous fistulas (AVFs). This cross-sectional study investigated whether high AVF flow had an impact on right ventricular function in patients undergoing hemodialysis. Sixty-four patients aged between 18 and 85 years who were on routine hemodialysis with >2 hemodialysis sessions per week for at least 3 months via an AVF were studied. Patients with inadequate flow fistulas, severe chronic obstructive pulmonary disease, history of pulmonary embolism, primary pulmonary hypertension, severe mitral, aortic or pulmonary regurgitation, and/or stenosis were excluded. After an initial evaluation, 44 patients (mean age: 58.50 ± 16.84, male:female = 23:21) were considered eligible. Right ventricular function was assessed by tricuspid annular plane systolic excursion (TAPSE). AVF blood flow was measured with duplex ultrasound. There were 15 patients (34.1%) with a TAPSE of <16 mm. AVF blood flow was significantly higher in patients with impaired versus normal right ventricular function (1631.53 ± 738.17 vs. 1060.55 ± 539.92 min/ml, respectively, P = 0.003). Low left ventricular ejection fraction (odds ratio [OR]: 1.15, 95% confidence intervals [CI]: 1.007-1.334, P = 0.04), high interventricular septum thickness (OR: 1.64, 95% CI: 1.104-2.464, P = 0.01), and high AVF blood flow (OR: 1.00, 95% CI: 1.000-1.003, P = 0.03) were independent predictors of impaired right ventricular function. In addition to known risk factors that predominantly increase right ventricular afterload, excessive AVF blood flow was found to be independently associated with impaired right ventricular function, possibly by increasing right ventricular preload.

Right Ventricular Enlargement within Months of Arteriovenous Fistula Creation in 2 Hemodialysis Patients

Surgically created arteriovenous fistulae (AVF) for hemodialysis can contribute to hemodynamic changes. We describe the cases of 2 male patients in whom new right ventricular enlargement developed after an AVF was created for hemodialysis. Patient 1 sustained high-output heart failure solely attributable to the AVF. After AVF banding and subsequent ligation, his heart failure and right ventricular enlargement resolved. In Patient 2, the AVF contributed to new-onset right ventricular enlargement, heart failure, and ascites. His severe pulmonary hypertension was caused by diastolic heart failure, diabetes mellitus, and obstructive sleep apnea. His right ventricular enlargement and heart failure symptoms did not improve after AVF ligation. We think that our report is the first to specifically correlate the echocardiographic finding of right ventricular enlargement with AVF sequelae. Clinicians who treat end-stage renal disease patients should be aware of this potential sequela of AVF creation, particularly in the upper arm. We recommend obtaining preoperative echocardiograms in all patients who will undergo upper-arm AVF creation, so that comparisons can be made postoperatively. Alternative consideration should be given to creating the AVF in the radial artery, because of less shunting and therefore less potential for right-sided heart failure and pulmonary hypertension. A multidisciplinary approach is optimal when selecting patients for AVF banding or ligation.

The Pros and Cons of Preserving a Functioning Arteriovenous Fistula after Kidney Transplantation

The autologous arteriovenous fistula (AVF) for hemodialysis burdens the cardiovascular system with increased cardiac output and pulmonary artery pressure, increasing cardiovascular risk. This article reviews literature on the benefits and drawbacks of a functioning AVF after kidney transplantation and discusses the cardiovascular effects of AVF closure. Several cohort studies demonstrate a significant cardiac burden of an AVF and improvement of cardiac dimensions after AVF ligation. However, no randomized trials have been conducted on routine AVF closure after successful kidney transplantation. Therefore, clinical trials are warranted to evaluate whether the cardiovascular benefits of routine AVF closure outweigh the potential harm for patients after successful kidney transplantation.

Systemic Effects of Hemodialysis Access

Patients with advanced chronic kidney disease are at a high risk of cardiovascular events. Patients with end-stage renal disease have a particularly high morbidity and mortality, in part attributed to the complications and dysfunction related to vascular access in this population. Creation of an arteriovenous access for HD is considered standard of care for most patients and has distinct advantages including less likelihood of infections, less need for intervention, and positive impact on survival as compared with usage of a catheter. However, creation of an arteriovenous shunt incites a series of events that significantly impacts cardiovascular and neurohormonal health in both positive and negative ways. This article will review the short- and long-term effects of dialysis access on cardiovascular, neurohormonal, and pulmonary systems as well as a brief review of their effect on survival on HD. Presence of other comorbidities in a patient with dialysis access can amplify these effects, and these considerations are of paramount importance in individualizing the approach to not only the choice of vascular access but also the modality of kidney replacement therapy.

Cardiac complications of arteriovenous fistulas in patients with end-stage renal disease

Cardiovascular disease is the leading cause of the death in dialysis patients. Arteriovenous fistulas (AVFs) are associated with lower mortality and are viewed as the desired access option in most patients with advanced kidney disease needing dialysis. However, AVFs have significant and potentially deleterious effects on cardiac functions particularly in the setting of preexisting heart disease. This article provides a comprehensive and contemporary review to what is known about the impact of AVFs on: congestive heart failure, left ventricular hypertrophy, pulmonary hypertension, right ventricular dysfunction, coronary artery disease and valvular heart disease.

Thinking outside the box: a middle-aged man with new-onset dyspnoea on exertion and pedal oedema

We describe a diagnostic dilemma in a middle-aged man presenting with dyspnoea and bilateral pedal oedema who had been diagnosed with right heart failure based on clinical evidence. The evaluation for aetiology eventually led to discovery of an unusual extrathoracic cause, a left-to-right communication in the renal vasculature. Renal arteriovenous fistulae are rare and can be congenital, acquired or idiopathic. A left-to-right shunt typically presents with high-output cardiac failure involving the left and right sides of the heart. An atypical feature of this case was the finding of overt right heart failure in the setting of a normal left heart. Such a presentation has only been described in a few isolated case reports. Diagnostic approaches include CT angiography and cardiac catheterisation for haemodynamic measurements. The primary treatment options for arteriovenous fistulae are medical management, arterial embolisation and surgical repair.

Relationship between pulmonary hypertension, peripheral vascular calcification, and major cardiovascular events in dialysis patients

BACKGROUND

Pulmonary hypertension (PHT) is a recently recognized complication of chronic kidney disease. In this study, we investigated the association between PHT, peripheral vascular calcifications (VCs), and major cardiovascular events.

METHODS

In this retrospective study, we included 172 end-stage renal disease (ESRD) patients undergoing dialysis [hemodialysis (HD)=84, peritoneal dialysis=88]. PHT was defined as an estimated pulmonary artery systolic pressure>37 mmHg using echocardiography. The Simple Vascular Calcification Score (SVCS) was measured using plain radiographic films of the hands and pelvis.

RESULTS

The prevalence of PHT was significantly higher in HD patients (51.2% vs. 22.7%). Dialysis patients with PHT had a significantly higher prevalence of severe VCs (SVCS≥3). In multivariate analysis, the presence of severe VCs [odds ratio (OR), 2.68], mitral valve disease (OR, 7.79), HD (OR, 3.35), and larger left atrial diameter (OR, 11.39) were independent risk factors for PHT. In addition to the presence of anemia, severe VCs, or older age, the presence of PHT was an independent predictor of major cardiovascular events in ESRD patients.

CONCLUSION

The prevalence of PHT was higher in HD patients and was associated with higher rates of major cardiovascular events. Severe VCs are thought to be an independent risk factor for predicting PHT in ESRD patients. Therefore, in dialysis patients with PHT, careful attention should be paid to the presence of VCs and the occurrence of major cardiovascular events.

Incidence of arteriovenous fistula closure due to high-output cardiac failure in kidney-transplanted patients

BACKGROUND

Some hemodialysis patients develop arteriovenous (AV) fistulas with high flows. This volume overload can result in high-output cardiac failure. To date, predisposing access flow rates are unknown.

METHODS

A retrospective study of all kidney-transplant recipients at the Medical University of Innsbruck (MUI) from 2005 to 2010 included 797 patients with the following criteria: previous hemodialysis with a native AV fistula or a graft, sufficient function of the kidney transplant up to the time of the data analysis, and follow-up care at the MUI.

RESULTS

Twenty-nine of the 113 patients (25.7%) needed an AV fistula closure, mostly because of symptoms of cardiac failure. The mean shunt flow in the intervention group was 2197.2 mL/min, whereas the mean shunt flow in the non-intervention group was only 850.9 mL/min. Shunt closures were most frequently made in patients with upper-arm shunts (41.7%).

CONCLUSION

The necessity of shunt closure is not a rarity. Patients who underwent an AV fistula ligature had high access flows with about 2200 mL/min. As the symptoms of cardiac failure greatly improved after shunt closure, patients with high access flow may benefit from such an intervention.

Pulmonary hypertension in patients with chronic and end-stage kidney disease

Pulmonary hypertension is defined as a mean pulmonary artery pressure ≥25 mm Hg and is a recently recognized complication of chronic kidney disease and end-stage renal disease. There is significant epidemiological overlap with kidney disease and the underlying causes of World Health Organization group 1-4 pulmonary hypertension (pulmonary arteriopathy, left heart disease, chronic pulmonary disease, and chronic thromboembolic disease, respectively). In addition, an entity of 'unexplained pulmonary hypertension,' group 5, in patients with chronic kidney disease and end-stage renal disease has emerged, with prevalence estimates of 30-50%. The pathogenesis of pulmonary hypertension in this population is due to alterations in endothelial function, increased cardiac output, and myocardial dysfunction leading to elevated left heart filling pressure, with recent data suggesting that left heart dysfunction may account for the vast majority of pulmonary hypertension in patients with kidney disease. Pulmonary hypertension is an independent predictor of increased mortality in patients on dialysis and those undergoing kidney transplantation. This review summarizes what is known about the epidemiology, pathogenesis, transplantation outcomes, mortality, and treatment of pulmonary hypertension in patients with chronic kidney disease and end-stage renal disease.

Pulmonary hypertension in CKD

Pulmonary arterial hypertension is a rare disease often associated with positive antinuclear antibody and high mortality. Pulmonary hypertension, which rarely is severe, occurs frequently in patients with chronic kidney disease (CKD). The prevalence of pulmonary hypertension ranges from 9%-39% in individuals with stage 5 CKD, 18.8%-68.8% in hemodialysis patients, and 0%-42% in patients on peritoneal dialysis therapy. No epidemiologic data are available yet for earlier stages of CKD. Pulmonary hypertension in patients with CKD may be induced and/or aggravated by left ventricular disorders and risk factors typical of CKD, including volume overload, an arteriovenous fistula, sleep-disordered breathing, exposure to dialysis membranes, endothelial dysfunction, vascular calcification and stiffening, and severe anemia. No specific intervention trial aimed at reducing pulmonary hypertension in patients with CKD has been performed to date. Correcting volume overload and treating left ventricular disorders are factors of paramount importance for relieving pulmonary hypertension in patients with CKD. Preventing pulmonary hypertension in this population is crucial because even kidney transplantation may not reverse the high mortality associated with established pulmonary hypertension.

Reversible pulmonary hypertension in a kidney transplant with patent A-V fistula

Pulmonary hypertension (PH) occurs in end-stage renal disease (ESRD) patients on long-term haemodialysis (HD) using an arterio-venous (A-V) access and can be attenuated by either kidney transplantation per se or surgical fistula ligation/revision. We report an exceptional case with severe PH after kidney transplantation due to ESRD and prior chronic intermittent HD via a patent A-V fistula. Gold-standard right heart catheterization findings have—for the first time—proven that following surgical shunt ligation of the A-V fistula, haemodynamics normalized completely in this patient.

Improving prognosis estimation in patients with heart failure and the cardiorenal syndrome

The coexistence of heart failure and renal dysfunction constitutes the “cardiorenal syndrome” which is increasingly recognized as a marker of poor prognosis. Patients with cardiorenal dysfunction constitute a large and heterogeneous group where individuals can have markedly different outcomes and disease courses. Thus, the determination of prognosis in this high risk group of patients may pose challenges for clinicians and for researchers alike. In this paper, we discuss the cardiorenal syndrome as it pertains to the patient with heart failure and considerations for further refining prognosis and outcomes in patients with heart failure and renal dysfunction. Conventional assessments of left ventricular function, renal clearance, and functional status can be complemented with identification of coexistent comorbidities, medication needs, microalbuminuria, anemia, biomarker levels, and pulmonary pressures to derive additional prognostic data that can aid management and provide future research directions for this challenging patient group.

Complications of arteriovenous hemodialysis access: recognition and management

English language citations reporting complications of arteriovenous access for hemodialysis are critically reviewed and discussed. Venous hypertension, arterial steal syndrome, and high-output cardiac failure occur as a result of hemodynamic alterations potentiated by access flow. Uremic and diabetic neuropathies are common but may obfuscate recognition of potentially correctable problems such as compression or ischemic neuropathy. Mechanical complications include pseudoaneurysm, which may develop from a puncture hematoma, degeneration of the wall, or infection. Dysfunctional hemostasis, hemorrhage, noninfectious fluid collections, and access-related infections are, in part, manifestations of the adverse effects of uremia on the function of circulating hematologic elements. Impaired erythropoiesis is successfully managed with hormonal stimulation; perhaps, similar therapies can be devised to reverse platelet and leukocyte dysfunction and reduce bleeding and infectious complications.

Arterio-venous access in end-stage renal disease patients and pulmonary hypertension

Background: The syndrome of pulmonary hypertension (PHT) in end-stage renal disease (ESRD) has been described in patients on chronic hemodialysis (HD) therapy via arterial-venous (A-V) access. However, the exact timing for the development of the PHT is unknown. This study was designed to evaluate changes in pulmonary artery pressure (PAP) following creation of the vascular access.

Patients and Methods: PAP and cardiac-output (CO) values were recorded in 12 pre-dialysis patients without PHT a few months after the access formation, before treatment with HD was started, and the prevalence of PHT was calculated. Clinical data was compared between patients with and without PHT.

Results: The systolic PAP values were increased in “ve of the 12 pre-dialysis patients (42%) by 21±9 mm Hg to more than 35 mm Hg. Patients with and without PHT differed only in that CO was signi“cantly higher among the former.

Conclusions: The development of PHT following access formation represents a failure of the pulmonary circulation to accommodate the access-mediated elevated CO. Pre-dialysis patients scheduled for access formation should be screened for the presence of sub-clinical PHT. “Positive” patients should proceed to peritoneal dialysis or advance to kidney transplantation; rather than getting access and HD therapy.

Pulmonary hypertension in chronic dialysis patients with arteriovenous fistula: pathogenesis and therapeutic prospective

PURPOSE OF REVIEW

End-stage renal disease patients receiving chronic haemodialysis via arteriovenous access often develop various cardiovascular complications, including vascular calcification, cardiac-vascular calcification and atherosclerotic coronary disease. This review describes recently published studies that demonstrate a high incidence of pulmonary hypertension among patients with end-stage renal disease receiving long-term haemodialysis via a surgical arteriovenous fistula. Both end-stage renal disease and long-term haemodialysis via arteriovenous fistula may be involved in the pathogenesis of pulmonary hypertension by affecting pulmonary vascular resistance and cardiac output.

RECENT FINDINGS

Morbidity and mortality from cardiovascular disease are greatly increased in patients on maintenance haemodialysis therapy. Using Doppler echocardiography, we found a significant increase in cardiac output in 40% of chronic haemodialysis patients, probably related to the large arteriovenous access or altered vascular resistance as a result of the local vascular tone and function expressed by the imbalance between vasodilators such as nitric oxide, and vasoconstrictors such as endothelin-1.

SUMMARY

We propose different potential mechanisms as explanations for the development of pulmonary hypertension. Hormonal and metabolic derangement associated with end-stage renal disease might lead to pulmonary arterial vasoconstriction and an increase in pulmonary vascular resistance. Pulmonary arterial pressure may be further increased by high cardiac output resulting from the arteriole-venous access itself, worsened by commonly occurring anaemia and fluid overload.

The pathogenesis of pulmonary hypertension in haemodialysis patients via arterio-venous access

BACKGROUND

We recently have shown a high incidence of unexplained pulmonary hypertension (PHT) in end-stage renal disease (ESRD) patients on chronic haemodialysis (HD) therapy via arterio-venous (A-V) access. This study evaluated the possibility that PHT in these patients is triggered or aggravated by chronic HD via surgical A-V access, and the role of endothelin-1 (ET-1) and nitric oxide (NO) in this syndrome.

METHODS

Forty-two HD patients underwent clinical evaluation. Pulmonary artery pressure (PAP) was evaluated using Doppler echocardiography. Levels of ET-1 and NO metabolites in plasma were determined before and after the HD procedure and were compared between subgroups of patients with and without PHT.

RESULTS

Out of 42 HD patients studied, 20 patients (48%) had PHT (PAP = 46+/-2; range 36-82 mmHg) while the rest had a normal PAP (29+/-1 mmHg) (P<0.0001). HD patients with PHT had higher cardiac output compared with those with normal PAP (6.0+/-1.2 vs 5.2+/-0.9 l/min, P<0.034). HD patients, with or without PHT, had elevated plasma ET-1 levels compared with controls (1.6+/-0.7 and 2.4+/-0.8 fmol/ml vs 1.0+/-0.2, P<0.05) that remained unchanged after the HD procedure. HD patients without PHT and control subjects showed similar basal plasma levels of NO2 + NO3 (24.2+/-5.2 vs 19.7+/-3.1 microM, P>0.05) that was significantly higher compared with HD patients with PHT (14.3+/-2.3 microM, P<0.05). HD therapy caused a significant increase in plasma NO metabolites that was greater in patients without PHT (from 24.2+/-5.2 to 77.1+/-9.6 microM, P<0.0001, and from 14.3+/-2.3 to 39.9+/-11.4 microM, P<0.0074, respectively). Significant declines in PAP (from 49.8+/-2.8 to 38.6+/-2.2 mmHg, P<0.004) and cardiac output (CO) (from 7.6+/-0.6 to 6.1+/-0.3 l/min, P<0.03) were found in 11 HD patients with PHT that underwent successful transplantation. Similarly, temporary closure of the A-V access by a sphygmomanometer in eight patients with PHT resulted in a transient decrease in CO (from 6.4+/-0.6 to 5.3+/- 0.5 l/min, P = 0.18) and systolic PAP (from 47.2+/-3.8 to 34.6+/-2.8 mmHg, P<0.028).

CONCLUSIONS

This study demonstrates a high prevalence of PHT among patients with ESRD on chronic HD via a surgical A-V fistula. In view of the vasodilatory and antimitogenic properties of NO, it is possible that the attenuated basal and HD-induced NO production in patients with PHT contributes to the increased pulmonary vascular tone. Furthermore, the partial restoration of normal PAP and CO in HD patients that underwent either temporal A-V shunt closure or successful transplantation indicates that excessive pulmonary blood flow is involved in the pathogenesis of the disease.

Pulmonary hypertension in the setting of acquired systemic arteriovenous fistulas

We describe 2 patients who presented with symptoms and clinical evidence of pulmonary hypertension. The first patient, who had severe pulmonary hypertension, underwent correction of an acquired arteriovenous (AV) fistula, which led to improvement according to clinical and noninvasive hemodynamic criteria. The second patient had severely symptomatic pulmonary hypertension associated with a large, previously unrecognized, superior mesenteric AV fistula after intra-abdominal surgery. Surgical correction of the fistula resulted in normalization of pulmonary hemodynamics assessed by right heart catheterization. Truly reversible substrates of pulmonary hypertension are rare. Acquired systemic AV fistulas are a less recognized cause of secondary pulmonary hypertension. It is unknown whether high blood flow peripheral AV shunts ultimately lead to endothelial proliferation, vascular smooth muscle hypertrophy, plexiform lesions, and other histopathologic changes that are seen in patients with left-to-right shunts due to atrial septal defects, ventricular septal defects, and patent ductus arteriosus.