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A complication is an event or occurrence that is associated with a disease or a healthcare intervention, is a departure from the desired course of events, and may cause, or be associated with suboptimal outcome. A complication does not necessarily represent a breech in the standard of care that constitutes medical negligence or medical malpractice. An operative or procedural complication is any complication, regardless of cause, occurring (1) within 30 days after surgery or intervention in or out of the hospital, or (2) after 30 days during the same hospitalization subsequent to the operation or intervention. Operative and procedural complications include both intraoperative/intraprocedural complications and postoperative/postprocedural complications in this time interval.
The MultiSocietal Database Committee for Pediatric and Congenital Heart Disease has set forth a comprehensive list of complications associated with the treatment of patients with congenital cardiac disease, related to cardiac, pulmonary, renal, haematological, infectious, neurological, gastrointestinal, and endocrine systems, as well as those related to the management of anaesthesia and perfusion, and the transplantation of thoracic organs. The objective of this manuscript is to examine the definitions of operative morbidity as they relate specifically to the neurological system. These specific definitions and terms will be used to track morbidity associated with surgical and transcatheter interventions and other forms of therapy in a common language across many separate databases.
Although neurological injury and adverse neurodevelopmental outcome can follow procedures for congenital cardiac defects, much of the variability in neurological outcome is now recognized to be more related to patient specific factors rather than procedural factors. Additionally, the recognition of pre and postoperative neurological morbidity requires procedures and imaging modalities that can be resource-intensive to acquire and analyze, and little is known or described about variations in “sampling rate” from centre to centre.
The purpose of this effort is to propose an initial set of consensus definitions for neurological complications following congenital cardiac surgery and intervention. Given the dramatic advances in understanding achieved to date, and those yet to occur, this effort is explicitly recognized as only the initial first step of a process that must remain iterative. This list is a component of a systems-based compendium of complications that may help standardize terminology and possibly enhance the study and quantification of morbidity in patients with congenital cardiac malformations. Clinicians caring for patients with congenital cardiac disease may be able to use this list for databases, initiatives to improve quality, reporting of complications, and comparing strategies of treatment.
As operative mortality after surgery for complex congenital cardiac disease continues to decrease, focus has shifted to efforts to recognize and mitigate other morbidities. Adverse neurodevelopmental outcome, and other neurological injuries, remain common after intervention for congenital cardiac disease.1 Early research efforts to decrease neurological injury focused on modifying intraoperative techniques of management,2 and advances in these techniques have been modestly successful. However, in the current era, surgeons and their teams are no longer solely responsible for further understanding and further advances. Many centres now recognize that non-modifiable patient-related factors are more important determinants of adverse neurodevelopmental outcome.3 With studies describing abnormal fetal brain development4 and brain perfusion,5 congenital cardiac disease is, in many cases, accompanied by congenital brain disease.6,7
It seems reasonable that further advances in improving care will be aided by having a common language across disciplines for describing abnormal findings in the central nervous system recognized before, during, and after interventions for congenital cardiac disease. However, the creation of this common language to describe neurological complications associated with the treatment of patients with congenital cardiac disease is a very challenging area in which to tread. Even the frequently mentioned construct, “postoperative complication”, gives the impression that the operation and/or the surgical team makes or breaks the occurrence of injury. For neurological disease, this assumption is simply not always true. Evidence is accumulating that multiple factors may be as important, or more important, than intraoperative factors in overall outcomes, including the factors from the following domains:
Identifying perioperative neurological injury may be challenging. Normal findings on physical examination and diagnostic studies are poorly sensitive for longer term neurological dysfunction, and these normal findings can have limited predictive validity. Similarly, the specificity of early postoperative findings for long term neurological and developmental abnormalities is also limited, with surprising ability of the neonatal and infant brain to withstand and recover from perioperative injury. Most structural neurological injury in the perioperative period is diagnosed with imaging modalities of magnetic resonance imaging or computed tomography, while functional abnormalities are typically assessed by electroencephalography and physical examination. However, beyond routine physical examination, advanced assessment of structure and function are rarely carried out. The vast majority of seizures and strokes are clinically silent after cardiac surgery. The neonatal physical examination is widely regarded to be of little prognostic value in predicting neurological outcome. Given the limited sensitivity and specificity of these studies, clinicians must balance the risks and benefits of cost, time, utilization of human resources, and other potential risks in moving a critically ill patient for a lengthy neuroimaging study requiring complete immobilization for adequate imaging.
It is with this understanding that candidate definitions for neurological complications are presented as only the first step of the work required to improve care in this area. Standardizing every aspect of neurological care is beyond the scope of this work. As technology, care, and understanding advance, it is anticipated that these definitions will be in need of revision. We believe that a common language and definitions are likely to improve neurological care and outcomes of children with congenital cardiac disease. However, it is important to recognize that standardization may also have unintended consequences8 that are not yet foreseen.
The terms in the final list of neurological complications developed by The MultiSocietal Database Committee for Pediatric and Congenital Heart Disease, along with their official definitions, are listed in Part 4 of this Supplement.
While many of the definitions were relatively straightforward to draft, some areas required further inquiry and discussion.
“A stroke is any confirmed neurological deficit of abrupt onset caused by a disturbance in blood flow to the brain, when the neurologic deficit does not resolve within 24 hours.”
“A reversible ischemic neurologic deficit (RIND) is defined as the loss of neurological function with symptoms at least 24 hours after onset but with complete return of function within 72 hours. In other words, a transient disturbance of perfusion to a localized part of the brain which produces a temporary, focal lesion with defined deficiency of neurologic function lasting from 24 to 72 hours, but not resulting in sustained symptoms or injury. Because a stroke is defined as “any confirmed neurological deficit of abrupt onset caused by a disturbance in blood flow to the brain, when the neurologic deficit does not resolve within 24 hours”, a RIND is a subtype of a stroke where the loss of neurological function and symptoms completely resolve within 72 hours.”
“A transient ischemic attack (TIA) is the temporary loss of neurological function resulting from temporary occlusion of blood flow in a cerebral artery, but without resulting in permanent brain injury. Most symptoms last less than 5 minutes but may last hours — up to 24 hours.”
It is hoped, but by no means guaranteed, that the gains of having this initial carefully thought out, but admittedly imperfect system, will outweigh the risks. Follow-up work, auditing, reassessment, and future iterative development will all be necessary.
Since the advent of paediatric cardiothoracic surgery, there has been an interesting evolution in the understanding of interactions between the neurological and cardiovascular systems of those affected by congenital cardiac disease. Early authors and sources12 lament the devastating effect on the developing brain of undiagnosed and untreatable cardiovascular disease. With profound circulatory collapse at presentation, or with the secondary effects of polycythemia and chronic cyanosis at later stages, the secondary effects on the brain were severe. With developments in surgical and medical therapies, efforts appropriately turned towards finding ways of minimizing the effects of cardiopulmonary bypass and other therapies. The current era involves improved rates of survival with efforts to mitigate the surprisingly high rate of adverse neurodevelopmental outcomes in the survivors. Careful work has shown that these adverse outcomes are multifactorial. In contrast to the model based solely in the operating room, it is now recognized that variation in intraoperative management fails to account for the majority of variability in neurodevelopmental outcomes.3 Through work on growth and development of the fetal brain, as well as preoperative and postoperative management in the intensive care unit, it is now clear that congenital cardiac disease rarely occurs in isolation — many affected patients have pre-existing and lifelong secondary effects on their neurological systems. Postoperative neurological complications are, in the current era, probably only one small part of this overall spectrum of effect.
This manuscript represents a multidisciplinary, collaborative, initial effort to improve the global dialogue, reporting, and understanding of neurological complications associated with the treatment of patients with congenital cardiac disease. Despite unintended consequences that may occur with the limitations and controversies described above, it is hoped that this effort helps to achieve its true primary goal — a salutary effect on communication and collaboration towards better neurodevelopmental outcomes.
We thank The Children’s Heart Foundation (http://www.childrensheartfoundation.org/) for financial support of this research.