The haematocrit – an important factor causing impaired haemostasis in patients with cyanotic congenital heart disease

Cardiac Drugs in ACHD Cardiovascular Medicine

Adult congenital heart disease (ACHD) is a growing population that requires life-long care due to advances in pediatric care and surgical or catheter procedures. Despite this, drug therapy in ACHD remains largely empiric due to the lack of clinical data, and formalized guidelines on drug therapy are currently lacking. The aging ACHD population has led to an increase in late cardiovascular complications such as heart failure, arrhythmias, and pulmonary hypertension. Pharmacotherapy, with few exceptions, in ACHD is largely supportive, whereas significant structural abnormalities usually require interventional, surgical, or percutaneous treatment. Recent advances in ACHD have prolonged survival for these patients, but further research is needed to determine the most effective treatment options for these patients. A better understanding of the use of cardiac drugs in ACHD patients could lead to improved treatment outcomes and a better quality of life for these patients. This review aims to provide an overview of the current status of cardiac drugs in ACHD cardiovascular medicine, including the rationale, limited current evidence, and knowledge gaps in this growing area.

Hematological indices in pediatric patients with acyanotic congenital heart disease: a cross-sectional study of 248 patients

Background

Congenital heart disease CHD is a significant cause of mortality and morbidity in children worldwide. Patients with congenital heart disease may develop hematological problems, including thrombocytopenia and neutropenia. In addition, several studies indicate the higher frailty of patients with CHDs to infections and malignancies. Nevertheless, the mechanisms of immune system changes in these patients have remained in the shadow of uncertainty. Moreover, very few studies have worked on cytopenia in CHD. This study has assessed the frequency of thrombocytopenia, neutropenia, lymphopenia, and anemia in pediatric patients with acyanotic congenital heart disease ACHD prior to open-heart surgery.

Methods

This cross-sectional study was handled in the Pediatric Cardiology Clinic, Tehran University of Medical Sciences, during pre-operation visits from 2014 till 2019. Two hundred forty-eight children and adolescents with acyanotic congenital heart disease before open-heart surgery met the criteria to enter the study.

Results

A total of 191 (76.7%) patients with Ventricular Septal Defects (VSD), 37 (14.85%) patients with Atrial Septal Defects (ASD), and 20 (8.11%) patients with Patent Ductus Arteriosus (PDA) were enrolled in this study. The median age was 23.87 months. Thrombocytopenia and neutropenia were found, respectively, in 3 (1.2) and 23 (9.2%) patients. Hemoglobin level and lymphocyte count were significantly lower in patients with neutropenia than patients with normal neutrophil count (P value = 0.024 and P value = 0.000). Significant positive correlations were found between neutropenia and anemia. There were no correlations between neutrophil count and Platelets. Also, anemia was found in 48 patients (19.3%). The study also found a statistically significant correlation between the co-existence of VSD and neutropenia in the patients (P value = 0.000).

Conclusion

Although most were mildly neutropenic, there was a significant correlation between neutropenia and Ventricular Septal Defect compared to PDA and ASD groups. Regarding the importance of neutropenia to affect the prognosis of congenital heart defects in infections, it is important to consider further studies on the status of immune system function in these patients.

Preoperative hematocrit and platelet count are associated with blood loss during spinal fusion for children with neuromuscular scoliosis

AIM

To assess the relationship of preoperative hematology laboratory results with intraoperative estimated blood loss and transfusion volumes during posterior spinal fusion for pediatric neuromuscular scoliosis.

METHODS

Retrospective chart review of 179 children with neuromuscular scoliosis undergoing spinal fusion at a tertiary children's hospital between 2012 and 2017. The main outcome measure was estimated blood loss. Secondary outcomes were volumes of packed red blood cells, fresh frozen plasma, and platelets transfused intraoperatively. Independent variables were preoperative blood counts, coagulation studies, and demographic and surgical characteristics. Relationships between estimated blood loss, transfusion volumes, and independent variables were assessed using bivariable analyses. Classification and Regression Trees were used to identify variables most strongly correlated with outcomes.

RESULTS

In bivariable analyses, increased estimated blood loss was significantly associated with higher preoperative hematocrit and lower preoperative platelet count but not with abnormal coagulation studies. Preoperative laboratory results were not associated with intraoperative transfusion volumes. In Classification and Regression Trees analysis, binary splits associated with the largest increase in estimated blood loss were hematocrit ≥44% vs. <44% and platelets ≥308 vs. <308 × 10⁹/L.

CONCLUSIONS

Preoperative blood counts may identify patients at risk of increased bleeding, though do not predict intraoperative transfusion requirements. Abnormal coagulation studies often prompted preoperative intervention but were not associated with increased intraoperative bleeding or transfusion needs.

Thromboembolic complications in adult congenital heart disease: the knowns and the unknowns

Despite impressive improvement in long-term survival, adults with congenital heart disease (CHD) remain exposed to a significant cardiovascular morbidity over lifetime. Thromboembolic events (TE) are a major issue. Specific anatomic groups have been shown a particular high risk of TE, including cyanotic heart disease and Fontan circulation. Many intercurrent clinical factors add a substantial risk such as intracardiac medical devices, atrial arrhythmia, endocarditis, or pregnancy. Nevertheless, what is unknown exceeds what is known, especially regarding the management of this heterogenous patient population. Anticoagulation decision should always be individualized weighing balanced with the alternative risk of hemorrhagic complications. In this review, we aim to synthetize existing literature on TE in adults with CHD, discuss management issues, highlight gaps in knowledge, and intend to suggest high priority research.

Value of Rotational Thromboelastometry and Impedance Aggregometry for Evaluating Coagulation Disorders in Patients With Cyanotic and Nongenetic Congenital Heart Disease

Adults with cyanotic congenital heart diseases (CCHD) have a higher risk for bleeding, but also for thrombosis. Rotational thromboelastometry (RT), using tissue factor (EXTEM), a contact activator (INTEM) or cytochalasin (FIBTEM), assesses coagulation by determining the time to initiation of clotting (CT) and clot firmness (MCF) including platelet-fibrin-interaction. The aim of this study was to evaluate RT and whole blood impedance aggregometry (IA) in CCHD compared with a control group without chronic cyanosis (NCCHD). These were used to establish normal reference ranges. We prospectively included 124 patients (76 CCHD, 48 NCCHD). Mean oxygen saturation in CCHD was 81.5%, and 98% in NCCHD (p <0.001). Fifty-five CCHD and 1 NCCHD had pulmonary hypertension. Eisenmenger syndrome was present in 39 CCHD (51.3%). Hemoglobin, hematocrit, and reticulocyte levels were significantly higher in CCHD, and they also showed more thrombocytopenia. Platelet aggregation was under normal range in 89.5% of CCHD after triggering with ADP, in 85.5% after triggering with arachidonic acid (ASPI) and in 73.7% after TRAP-6. RT showed significantly longer clotting times and reduced clot firmness in both EXTEM and INTEM tests. FIBTEM-MCF was also significantly reduced. Moderate inverse correlation was found between platelet count and erythrocytes (r = -0.608, p <0.001). Significant correlations were found between platelet number and RT-parameters as well as with all IA parameters. In conclusion, according to RT and IA, CCHD present hypocoagulable disorders. No signs of hypercoagulability were found.

Risk of thromboembolic complications in adult congenital heart disease: A literature review

Adult congenital heart disease (ACHD) is a constantly expanding population with challenging issues. Initial medical and surgical treatments are seldom curative, and the majority of patients still experience late sequelae and complications, especially thromboembolic events. These common and potentially life-threating adverse events are probably dramatically underdiagnosed. Better identification and understanding of thromboembolic risk factors are essential to prevent long-term related morbidities. In addition to specific situations associated with a high risk of thromboembolic events (Fontan circulation, cyanotic congenital heart disease), atrial arrhythmia has been recognized as an important risk factor for thromboembolic events in ACHD. Unlike in patients without ACHD, thromboembolic risk stratification scores, such as the CHA₂DS₂-VASc score, may not be applicable in ACHD. Overall, after a review of the scientific data published so far, it is clear that the complexity of the underlying congenital heart disease represents a major risk factor for thromboembolic events. As a consequence, prophylactic anticoagulation is indicated in patients with complex congenital heart disease and atrial arrhythmia, regardless of the other risk factors, as opposed to simple heart defects. The landscape of ACHD is an ongoing evolving process, and specific thromboembolic risk scores are needed, especially in the setting of simple heart defects; these should be coupled with specific trials or long-term follow-up of multicentre cohorts.

Past and current cause-specific mortality in Eisenmenger syndrome

Aims

Eisenmenger syndrome (ES) is associated with considerable morbidity and mortality. Therapeutic strategies have changed during the 2000s in conjunction with an emphasis on specialist follow-up. The aim of this study was to determine the cause-specific mortality in ES and evaluate any relevant changes between 1977 and 2015.

Methods and results

This is a retrospective, descriptive multicentre study. A total of 1546 patients (mean age 38.7 ± 15.4 years; 36% male) from 13 countries were included. Cause-specific mortality was examined before and after July 2006, 'early' and 'late', respectively. Over a median follow-up of 6.1 years (interquartile range 2.1-21.5 years) 558 deaths were recorded; cause-specific mortality was identified in 411 (74%) cases. Leading causes of death were heart failure (34%), infection (26%), sudden cardiac death (10%), thromboembolism (8%), haemorrhage (7%), and peri-procedural (7%). Heart failure deaths increased in the 'late' relative to the 'early' era (P = 0.032), whereas death from thromboembolic events and death in relation to cardiac and non-cardiac procedures decreased (P = 0.014, P = 0.014, P = 0.004, respectively). There was an increase in longevity in the 'late' vs. 'early' era (median survival 52.3 vs. 35.2 years, P < 0.001).

Conclusion

The study shows that despite changes in therapy, care, and follow-up of ES in tertiary care centres, all-cause mortality including cardiac remains high. Patients from the 'late' era, however, die later and from chronic rather than acute cardiac causes, primarily heart failure, whereas peri-procedural and deaths due to haemoptysis have become less common. Lifelong vigilance in tertiary centres and further research for ES are clearly needed.

Additive roles of platelets and fibrinogen in whole-blood fibrin clot formation upon dilution as assessed by thromboelastometry

Blood dilution after transfusion fluids leads to diminished coagulant activity monitored by rotational thromboelastometry, assessing elastic fibrin clot formation, or by thrombin generation testing. We aimed to determine the contributions of blood cells (platelets, red blood cells) and plasma factors (fibrinogen, prothrombin complex concentrate) to fibrin clot formation under conditions of haemodilution in vitro or in vivo. Whole blood or plasma diluted in vitro was supplemented with platelets, red cells, fibrinogen or prothrombin complex concentrate (PCC). Thromboelastometry was measured in whole blood as well as plasma; thrombin generation was determined in parallel. Similar tests were performed with blood from 48 patients, obtained before and after massive fluid infusion during cardiothoracic surgery. Addition of platelets or fibrinogen, in additive and independent ways, reversed the impaired fibrin clot formation (thromboelastometry) in diluted whole blood. In contrast, supplementation of red blood cells or prothrombin complex concentrate was ineffective. Platelets and fibrinogen independently restored clot formation in diluted plasma, resulting in thromboelastometry curves approaching those in whole blood. In whole blood from patients undergoing dilution during surgery, elastic clot formation was determined by both the platelet count and the fibrinogen level. Thrombin generation in diluted (patient) plasma was not changed by fibrinogen, but improved markedly by prothrombin complex concentrate. In conclusion, in dilutional coagulopathy, platelets and fibrinogen, but not red blood cells or vitamin K-dependent coagulation factors, independently determine thromboelastometry parameters measured in whole blood and plasma. Clinical decisions for transfusion based on thromboelastometry should take into account the platelet concentration.

Advanced Therapy in Eisenmenger Syndrome: A Systematic Review

Treatment options for patients with the Eisenmenger syndrome have until recently been scarce, but new knowledge in the field of pulmonary arterial hypertension has expanded the therapeutic possibilities for these patients. Advanced therapy with pulmonary vasodilators has become part of the standard treatment, offering long-term benefits on exercise capacity, clinical symptoms, and possibly survival. However, there are currently only few studies to guide the use of advanced therapies in this population, and important questions such as indications for initiation or escalation of advanced therapy and valid effect parameters and treatment goals remain unanswered. This review covers the pharmacology, therapeutic options, risk stratification, and treatment strategy of pulmonary arterial hypertension-specific drugs in patients with Eisenmenger syndrome.

Elevated hematocrit enhances platelet accumulation following vascular injury

Red blood cells (RBCs) demonstrate procoagulant properties in vitro, and elevated hematocrit is associated with reduced bleeding and increased thrombosis risk in humans. These observations suggest RBCs contribute to thrombus formation. However, effects of RBCs on thrombosis are difficult to assess because humans and mice with elevated hematocrit typically have coexisting pathologies. Using an experimental model of elevated hematocrit in healthy mice, we measured effects of hematocrit in 2 in vivo clot formation models. We also assessed thrombin generation, platelet-thrombus interactions, and platelet accumulation in thrombi ex vivo, in vitro, and in silico. Compared with controls, mice with elevated hematocrit (RBC^HIGH) formed thrombi at a faster rate and had a shortened vessel occlusion time. Thrombi in control and RBC^HIGH mice did not differ in size or fibrin content, and there was no difference in levels of circulating thrombin-antithrombin complexes. In vitro, increasing the hematocrit increased thrombin generation in the absence of platelets; however, this effect was reduced in the presence of platelets. In silico, direct numerical simulations of whole blood predicted elevated hematocrit increases the frequency and duration of interactions between platelets and a thrombus. When human whole blood was perfused over collagen at arterial shear rates, elevating the hematocrit increased the rate of platelet deposition and thrombus growth. These data suggest RBCs promote arterial thrombosis by enhancing platelet accumulation at the site of vessel injury. Maintaining a normal hematocrit may reduce arterial thrombosis risk in humans.

Bronchial artery embolization for the treatment of haemoptysis in pulmonary hypertension

PURPOSE

To test the efficacy of bronchial artery embolization (BAE) to treat haemoptysis in pulmonary hypertension (PH).

METHODS

33 patients were treated by BAE for haemoptysis associated with PH (PH group = 21) or non-associated with PH (control group = 12). The details of procedure, outcome, and rate of relapse were compared between the two groups. Within the PH group, the comparison was operated between subjects with congenital heart disease-associated pulmonary artery hypertension (CHD-APAH subgroup = 12) and non-CHD (non-CHD-APAH subgroup = 9).

RESULTS

The rate of relapse at 30 and 90-days was similar between the PH group and control group. BAE in the PH group was more challenging (median 2 arteries embolized per procedure) compared to the control group (median 1 artery embolized per procedure; p = 0.001). Bleeding arteries were more heterogeneous in the PH group, while a single right bronchial artery was the only clinical finding in 66.7% of controls (p = 0.001). Within the PH group, the CHD subgroup showed higher survival rate compared to the non-CHD-APAH group (p = 0.007).

CONCLUSION

BAE is effective and safe for the treatment of haemoptysis in PH, yet more challenging than other conditions. In PH-associated haemoptysis, BAE provides higher survival rate for subjects with PH associated with CHD.

Congenital Malformations Leading to Paradoxical Embolism

The absolute separation of the right and left circulations and the filtration of blood by the pulmonary circulation are essential to prevent the passage of thrombotic material from the venous system into the systemic arterial circulation. Any breach of the intracardiac septae or circumvention of the pulmonary capillary network may cause a paradoxical embolus. The most common causes are atrial septal defects and pulmonary arteriovenous malformations. This article discusses unusual connections and pathways related to congenital malformations. Although anticoagulation is necessary to prevent paradoxical emboli, the hematologic disturbances and the most appropriate therapy in these patients warrant further investigation.

Extra-cardiac manifestations of adult congenital heart disease

Advancement in correction or palliation of congenital cardiac lesions has greatly improved the lifespan of congenital heart disease patients, resulting in a rapidly growing adult congenital heart disease (ACHD) population. As this group has increased in number and age, emerging science has highlighted the systemic nature of ACHD. Providers caring for these patients are tasked with long-term management of multiple neurologic, pulmonary, hepatic, renal, and endocrine manifestations that arise as syndromic associations with congenital heart defects or as sequelae of primary structural or hemodynamic abnormalities. In this review, we outline the current understanding and recent research into these extra-cardiac manifestations.

Assessment of coagulation profile by thromboelastometry in adult patients with cyanotic congenital heart disease

BACKGROUND

Patients with cyanotic congenital heart disease (CCHD) have an increased risk of bleeding and thrombotic complications. Prolonged conventional coagulation screening parameters, such as activated partial thromboplastin time or prothrombin time, are reported in less than 20% of CCHD patients.

METHODS

The aim of this study was to determine the haemostatic abnormalities in 32 adult patients with CCHD by rotation thromboelastometry (ROTEM) with assessment of coagulation dynamic properties, as a guide for perioperative prophylaxis or haemostatic therapy. The control group consisted of 35 healthy subjects.

RESULTS

Our results suggest that CCHD patients, in comparison to healthy controls, had a tendency to hypocoagulate with delayed activation of haemostasis and clot formation, initiated by both intrinsic and extrinsic activators. The growth of the clot was slower and the clot firmness was decreased, which may additionally contribute to bleeding diathesis. Moreover, the clot lysis readings suggest higher clot stability in the CCHD group. All velocity parameters were markedly lower in the CCHD patients, indicating a decreased rate of clot formation. Although coagulation tests and platelet count were normal, the usefulness of rotation thromboelastometry in monitoring or guiding therapy in CCHD patients is demonstrated.

CONCLUSION

In conclusion, our results provide new insights into the data on hypocoagulation with impaired clot lysis in adult CCHD patients as determined by ROTEM. Our findings may assist in determining the optimal management of patients with CCHD undergoing surgery.

Critical care management of the adult patient with congenital heart disease: focus on postoperative management and outcomes

OPINION STATEMENT

Advances in surgical techniques and in the medical management of children with congenital heart disease has increased survival into adulthood, resulting in a population of adults with congenital heart disease now surpassing the pediatric population in numbers. Furthermore, many of the patients will require repeat surgical, catheter-based, procedures and/or obstetrical care in their adult lives, and understanding the specific cardiopulmonary physiology and the involvement of other organ systems is critical to successful intervention. A team approach, with consultants from medical specialties in the setting of an established adult congenital heart center, is the optimal setting for superior outcomes. In this review, we discuss critical care management of the adult congenital heart disease patient in the perioperative period.

Clinical implications of haemoptysis in patients with pulmonary arterial hypertension

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a disabling disease that may result in haemoptysis. Patients with congenital heart disease associated PAH (CHD-APAH) may have a survival advantage when compared with patients with other types of PAH presenting with haemoptysis. The effects of aetiology and subsequent management choice of haemoptysis in PAH patients is not well-defined.

METHODS

We conducted outcome analysis in CHD-APAH vs. all other subtypes of PAH patients presenting with haemoptysis to The Methodist Hospital. Twenty-one patients were identified, 13 patients in the CHD-APAH group and eight patients in the non-CHD group. We evaluated outcomes related to treatment (bronchial artery embolisation (BAE) vs. conservative management), hospital length of stay, mortality rates and survival in this cohort.

RESULTS

The CHD-APAH and non-CHD groups had similar baseline demographic, haemodynamic and laboratory values except BMI was higher in the non-CHD group and haematocrit was higher in the CHD-APAH group. Twenty-eight-day mortality (0% vs. 31%) and 1-year mortality (0% vs. 54%) was lower in the CHD-APAH patients as compared with non-CHD group. A statistically significant difference was found in the survival rate in favour of CHD-APAH group for the total follow-up period (p = 0.02). Although not statistically significant, patients treated with BAE had shorter length of stay (4.0 days ± 4.0 vs. 13.7 days ± 22.5; p = 0.26). There was recurrent haemoptysis in 43% of patients treated with BAE.

CONCLUSION

Haemoptysis in PAH patients is a serious event with a high mortality rate. CHD-APAH seems to confer a survival advantage, independent of therapy utilised. Termination of haemoptysis with BAE is rapid with relatively few complications except for frequent re-bleeding episodes. Further studies are needed to determine the risk factors that may predispose PAH patients to excessive mortality from haemoptysis and to identify an optimal therapeutic modality.