Left ventricular thrombosis following a Norwood procedure

Intracardiac thrombosis after congenital heart disease surgeries in neonates: a report of two cases

BACKGROUND

Intracardiac thrombosis (ICT) is a rare complication after the cardiopulmonary surgery for interrupted aortic arch (IAA) or total anomalous pulmonary venous connection (TAPVC) without previous records. There are still no general guidelines regarding as the mechanism or management of postoperative ICT in neonates and younger infants.

CASE PRESENTATION

We reported the conservative and surgical therapies in two neonates with intra-ventricular and intra-atrial thrombosis after the anatomical repair for IAA and TAPVC, respectively. There were no risk factors for ICT in both patients, except for the use of blood product and prothrombin complex concentrate. The surgery was indicated after TAPVC correction due to the worsening respiratory status and rapidly decreased mixed venous saturation. Anticoagulation combined with antiplatelet therapies was adopted in another patient. These two were both finally recovered, and three-month, six-month, and one-year follow-up echocardiography revealed no abnormality.

CONCLUSIONS

ICT is uncommon in pediatric population after the surgery for congenital heart disease. Single ventricle palliation, heart transplantation, longer central line use, post-extracorporeal membrane oxygenation, and massive blood product use are major risk factors for postcardiotomy thrombosis. The causes of postoperative ICT are multifactorial, and the immaturity of thrombolytic and fibrinolytic system in neonates may serve as a prothrombotic factor. However, no consensus reached regarding as the therapies for postoperative ICT, and the large-scale prospective cohort study or randomized clinical trial is needed.

Incidence and Management of Thrombotic and Thromboembolic Complications Following the Norwood Procedure: A Systematic Review

Background:

The stage 1 Norwood procedure and its variants represent the first step of palliation for hypoplastic left heart syndrome. Although appropriate postoperative thromboprophylaxis is integral, significant variance remains across institutional practices. The purpose of this systematic review is to estimate the incidence of thrombosis and thromboembolism following the Norwood or modified Blalock-Taussig shunt procedure and examine current thromboprophylaxis regimens.

Methods:

Ovid MEDLINE and Embase were searched from January 2000 to June 2016 for primary studies explicitly reporting incidence of thrombosis, thromboembolism (strokes and pulmonary embolisms), or shunt occlusion in neonates, infants, and children undergoing the Norwood procedure or any variant. All-cause mortality was a secondary outcome of interest.

Results:

Of 887 identified articles, 15 cohort studies were deemed eligible, the majority including modified Blalock-Taussig shunt patients. Reported incidence of thrombosis ranged from 0% to 40%; thromboembolic events were rarely reported. Overall mortality ranged from 4.5% to 31.3% across studies. Although most studies involved the long-term acetylsalicylic acid use, thromboprophylaxis strategies varied across studies. Due to substantial variability in event rates, no correlation was identified with thrombotic complications.

Discussion:

Clinical practice guidelines recommend that patients receive intraoperative unfractionated heparin therapy and either aspirin or no antithrombotic therapy postoperatively. Our findings suggest a substantial risk of thrombosis and thromboembolism and demonstrate substantial variation in thromboprophylaxis practices.

Conclusion:

Although postoperative thromboprophylaxis seems optimal, it remains controversial whether the long-term aspirin use is most effective. Our findings highlight the lack of a gold-standard thromboprophylaxis strategy and emphasize the need for more consistency.

Neoaortic thrombus after Norwood procedure: complication of extracorporeal life support?

Hypoplastic left heart syndrome is the most common diagnosis among infants requiring cardiac extracorporeal life support (ECLS) in the neonatal period, with more than half of patients experiencing an ECLS-related complication. We present a case of nearly obstructing neoaortic thrombus during ECLS occurring in the early postoperative period after modified Norwood palliation of hypoplastic left heart syndrome. Stasis within the neoaortic root due to the increased ventricular afterload associated with venoarterial ECLS may have potentiated this complication. Echocardiographic monitoring and early cardiac catheterization while on ECLS enabled prompt diagnosis and timely surgical correction.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.