Distribution and Clinical Signs of Venous, Arterial and Intracardiac Clots After Pediatric Cardiac Surgery.
Authors: Brandao Leonardo R. , Manlhiot Cedric , Menjak Ines B. , Chan Anthony , Carew Caitlin , Gruenwald Colleen E. , Schwartz Steven M. , Sivarajan Ben V. , McCrindle Brian W. 
Published: October 2019

Abstract
Abstract 3992
Poster Board III-928

Background
Very little is known about the occurrence of venous and arterial clots after pediatric cardiac surgery. To date, no studies have explored the distribution of clots throughout the different limbs/organ systems in this patient population. Furthermore, because many clots are asymptomatic or have non-specific clinical signs, there is a lack of clinical suspicion contributing to under-diagnosis and under-treatment of many patients, potentially leading to serious consequences.

Methods
A total of 1,542 cardiac surgeries in patients 0-18 years from September 2004 to December 2007 were reviewed. Patients with clots identified in the early post-operative period (up to hospital discharge) were further investigated. Clots were classified according to their limb/organ and vascular system locations. Clots not associated with limb swelling, discoloration, pain, localized changes in temperature or peripheral pulses were classified as asymptomatic.

Results
A total of 204 patients (13.2%) experience at least 1 thrombotic event, 122 surgeries (7.9%) were associated with venous clots (53 lower limbs, 34 upper limbs, 16 hepatic/renal/portal veins, 29 inferior or superior vena cava and 56 jugular vein, brachiocephalic vein or cerebral veins). In the arterial system 32 (2.1%) surgeries were associated with arterial clots (20 lower limbs, 2 upper limbs and 12 carotid artery, brachiocephalic artery or cerebral arteries). A further, 20 surgeries (1.3%) were associated with either intracardiac clots, primary pulmonary clots, intra aortic clots, pulmonary veins or arteries clots. Clots in 2 or more vascular systems (venous, arterial or cardiac) were found in 22 patients (1.4%). A higher proportion of patients with arterial clots were found to have clots in the lower limbs compared to those with venous clots (69% vs. 45%, p=0.04) the reverse was true for clots in the upper limbs (7% vs. 27%, p=0.02). There were no differences between vascular systems in terms of proportion of patients with clots in the cerebral veins and arteries (35% vs. 45%, p=0.21). Patients with venous clots were more likely to have clots in multiple locations than patients with arterial clots (38% vs. 0%, p<0.001). Overall 22% of patients were asymptomatic (23% of patients with venous clots, 16% of patients with arterial clots and 22% of patients with cardiac clots). There was no significant differences in the proportion of asymptomatic clots by limbs/organ system for clots either in the arterial or venous system. Of the patients with thrombotic complications, 19 (1.2%) had a stroke (12 ischemic, 4 sinovenous, 3 hemorrhagic), 16 (1.0%) had a cerebral haemorrhage and 4 patients had a pulmonary embolism. Furthermore, 87 (43%) of patients with thrombosis required either thrombolysis with tissue plasminogen activator (tPa), reoperation, re-catheterization or died prior to hospital discharge. This composite outcome was more likely in patients with clots in multiple systems (OR: 1.9, p=0.02), clots in the arterial vascular system (OR: 2.6, p=0.02) and for patients with clots in the carotid artery, brachiocephalic artery or cerebral arteries (OR: 4.4, p=0.03). Asymptomatic clots were slightly less likely to be associated with complications (OR: 0.5, p=0.09).

Conclusion
After pediatric cardiac surgeries, venous clots tend to spread throughout the body while arterial clots congregated in the upper limbs and cerebral arteries. Because almost one in four clots after pediatric cardiac surgery are asymptomatic, a high-index of suspicion is recommended in this population.

Disclosures:
No relevant conflicts of interest to declare.