Key result
Pediatric TOF cyanotic spells lack standardized definitions and validated predictors, with propranolol most studied.
Why the study?
Cyanotic spells in children with Tetralogy of Fallot can cause severe hypoxemia, neurological manifestations, and hemodynamic compromise, yet evidence on their definition, pathophysiology, predictors, management, and outcomes remains heterogeneous and seldom analyzed.
This scoping review highlights substantial heterogeneity in defining and reporting cyanotic spells in pediatric Tetralogy of Fallot, underscoring the lack of validated predictive models and the need for standardized definitions and prospective studies.
Answers are grounded in this paper and cite their sources.
Heterogeneous evidence on TOF cyanotic spells warrants cautious management; leaves open standardized definitions and prospective trials.
Background: Cyanotic or hypercyanotic spells are acute episodes of worsening cyanosis in children with Tetralogy of Fallot (TOF), potentially causing profound hypoxemia, neurological manifestations, and hemodynamic compromise. Evidence regarding their definition, pathophysiology, predictors, management, and outcomes remains heterogeneous and seldom analyzed. Aim: Our aim is to systematically map the evidence on cyanotic spells in pediatric patients with TOF, focusing on clinical presentation, precipitating factors, mechanisms, predictors, management, and outcomes. Methods: Under PRISMA-ScR guidelines for scoping review, we searched the PubMed/MEDLINE electronic database for English-language original manuscripts published up to August 2026, supplemented by reference-list screening. Original studies reporting extractable TOF-specific cyanotic-spell data in pediatric patients were eligible. Two reviewers independently screened records, and we descriptively synthesized the extracted data. Results: A total of 39 studies were included, comprising physiological investigations, case reports and series, observational cohorts, pharmacological studies, and catheter-based interventions. Heterogeneous terminology, definitions, clinical characterization, and outcome reporting were noted. Cyanotic spells were characterized by episodic worsening of cyanosis, often accompanied by hyperpnea and, in severe episodes, neurological manifestations. Available evidence suggests a potential interaction between right ventricular outflow tract (RVOT) anatomy and dynamic physiological factors. Conal septal geometry has been proposed as a potential anatomical marker, whereas available evidence suggests limited predictive value of peak Doppler RVOT gradient. Propranolol was the most extensively investigated pharmacological treatment strategy. More recent studies evaluated balloon-based interventions and RVOT stenting; selected reports described improved oxygenation and control or reduction of recurrent spells. Comparative and long-term evidence was limited. Conclusions: Cyanotic spells remain a potentially severe clinical manifestation in children with TOF. No validated predictive model is currently available, and only a limited number of candidate predictors have been directly evaluated. Standardized definitions and prospective studies integrating clinical, anatomical, echocardiographic, and physiological variables are needed to improve risk stratification and evaluate subsequent outcomes.
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Andrejic et al. (2026) conducted a review in Cyanotic spells in pediatric Tetralogy of Fallot (TOF). Across 39 studies of pediatric TOF cyanotic spells, definitions and outcomes were heterogeneous, no validated predictive model existed, and propranolol was the most studied therapy.
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