1,329 calculators and references across 60 specialties, with formula confidence shown up front.
Aortic Root Z-Score (Boston Formula): Explanation and Clinical Context The Aortic Root Z-score is a body size–adjusted measurement that quantifies how a patient’s aortic root dimension compares to population-based reference values. The Boston formula, derived from pediatric and young adult cohorts, provides a reliable way to normalize aortic root diameter according to body surface area (BSA). A Z-score represents the
Aristotle Basic Complexity Score (ABCS): Explanation and Clinical Context The Aristotle Basic Complexity Score is a validated tool designed to estimate the procedural complexity for congenital heart surgery in pediatric and adult patients. It combines factors such as the type of surgical procedure, patient age, presence of noncardiac congenital abnormalities, and genetic abnormalities. Each factor is assigned a weigh
Aristotle Comprehensive Complexity (ACC) Score: Explanation and Clinical Context The ACC Score is designed to quantify the overall surgical complexity in congenital heart surgery by combining the Aristotle Basic Complexity (ABC) score with procedure-dependent modifiers and patient-dependent modifiers. The ABC score (range ~1.5 to 15) itself is derived from three domains: potential mortality, potential morbidity, and
AVSD Surgical Mortality Score: Explanation and Clinical Context The AVSD Surgical Mortality Score is a predictive tool to estimate the risk of operative mortality in patients undergoing repair for atrioventricular septal defect (AVSD). It incorporates key preoperative variables, including age, weight, presence of Down syndrome, preoperative ventricular dysfunction, and pulmonary hypertension. The score uses a logisti
Bronchopulmonary Dysplasia–Pulmonary Hypertension (BPD–PH) Severity Classification: Explanation and Clinical Context BPD–PH is a serious complication of bronchopulmonary dysplasia in preterm infants, associated with increased morbidity and mortality. Classification of severity combines oxygen requirement at 36 weeks postmenstrual age and echocardiographic evidence of pulmonary hypertension. Mild BPD-PH indicates low
CHOP-CHD Neurodevelopmental Risk Index: Explanation and Clinical Context The CHOP-CHD Neurodevelopmental Risk Index is a validated tool designed to estimate the probability of neurodevelopmental impairment in children following congenital heart disease (CHD) surgery. It incorporates key clinical and perioperative variables, including gestational age, birth weight, presence of single ventricle physiology, duration of
Eisenmenger Pediatric Transition Index (EPTI): Explanation and Clinical Context The Eisenmenger Pediatric Transition Index (EPTI) is a composite score designed to estimate the risk of adverse events during the transition from pediatric to adult care in patients with Eisenmenger syndrome. It incorporates four clinical parameters: age, oxygen saturation, hematocrit, and NYHA functional class. Lower oxygen saturation, h
Fontan Failure Index: Explanation and Clinical Context The Fontan Failure Index aims to integrate hemodynamic burden (e.g. elevated central venous pressure, reduced cardiac index) and hepatic injury (represented by liver stiffness by elastography and thrombocytopenia as marker of portal hypertension) to stratify risk of clinical Fontan failure. A higher score suggests greater circulatory stress and end‑organ (hepatic
Fontan Risk Score: Explanation and Clinical Context The Fontan Risk Score is a clinical tool developed to predict early mortality risk for patients undergoing the Fontan procedure, both pre- and post-operatively. It incorporates key variables such as age at Fontan, preoperative oxygen saturation, ventricular dysfunction, atrioventricular valve regurgitation, and history of arrhythmia. Each risk factor is assigned a w
: Explanation & Clinical Context This model estimates the probability of having a complicated Glenn procedure (cGP) after a bidirectional Glenn operation. The cGP concept is derived from Khaira et al (2023), where they defined a composite endpoint of mortality or significant postoperative complications by 2 years. In their multivariable analysis, higher inotrope score on postoperative day 1 (HR ≈ 1.04 per unit) and u
HLHS Norwood Survival Predictor: Explanation and Clinical Context The HLHS Norwood Survival Predictor estimates the probability of survival following the Norwood procedure in neonates with Hypoplastic Left Heart Syndrome (HLHS). It uses key preoperative clinical variables, including birth weight, gestational age, need for preoperative mechanical ventilation, and presence of coronary artery anomalies. Lower birth weig
Kawasaki Disease Coronary Z-score: Explanation and Clinical Context The Kawasaki Disease Coronary Z-score is a standardized metric that quantifies coronary artery dilation relative to body surface area (BSA) in pediatric patients. It is calculated by comparing the measured coronary artery diameter to the predicted mean diameter for a given BSA, normalized by the standard deviation (SD) derived from population-based r
Kawashima Operation Survival Index: Explanation and Clinical Context The Kawashima Operation Survival Index is a risk prediction tool used to estimate long-term survival probability for patients undergoing the Kawashima procedure, typically for patients with single ventricle physiology and interrupted inferior vena cava with azygos continuation. It incorporates key clinical variables including age at surgery, preoper
M-Boston Score (Mitral Arcade Surgical Outcome): Explanation and Clinical Context This scoring model is designed to predict surgical outcomes in patients with mitral arcade anomaly undergoing mitral valve surgery. It incorporates preoperative and intraoperative variables such as leaflet involvement, annular dimension, chordal extension, and ventricular function. A higher score indicates a (worse/better) surgical outc
Modified Ross Score: Explanation and Clinical Context The Modified Ross Score is a validated tool used to assess the severity of heart failure in infants and children, particularly in those with congenital heart disease. It evaluates five key clinical parameters: heart rate at rest, respiratory rate, feeding difficulty, diaphoresis, and exercise intolerance or cyanosis. Each parameter is scored according to severity,
Neonatal Pulmonary Hypertension (NPH) Risk Index: Explanation and Clinical Context The Neonatal Pulmonary Hypertension Risk Index is a validated scoring system designed to stratify the risk of pulmonary hypertension in neonates, particularly preterm infants. It incorporates key clinical variables available shortly after birth, including gestational age, birth weight, need for mechanical ventilation, and oxygenation i
PDA Severity Score (PDAsc) — Explanation and Clinical Context The PDA Severity Score (PDAsc) is a multivariable echocardiography-based prognostic index developed to quantify early hemodynamic significance of a patent ductus arteriosus in very preterm infants and predict the composite outcome of chronic lung disease or death before discharge. The score combines gestational age, echocardiographic PDA diameter (pulmonar
CRISP Pediatric Cardiac Catheterization Risk Score: Explanation and Clinical Context The CRISP (Catheterization RISk Score for Pediatrics) model is a validated risk tool to predict serious adverse events (SAEs) in pediatric patients undergoing cardiac catheterization. } It incorporates multiple pre‑procedural variables (age, procedure risk level, hemodynamic vulnerability, use of inotropes or mechanical support, emer
Pediatric Cardiomyopathy Mortality Score: Explanation and Clinical Context The Pediatric Cardiomyopathy Mortality Score is a clinical tool designed to estimate the 1-year mortality risk in children diagnosed with primary cardiomyopathy. It integrates patient age, left ventricular systolic function (fractional shortening), left ventricular size (LVEDD z-score), serum BNP levels, and the presence of arrhythmias. Lower
Pediatric Heart Failure Severity Index (Ross Classification): Explanation and Clinical Context The Ross Classification is a widely used clinical scoring system to assess the severity of heart failure in infants and young children. It evaluates symptoms such as feeding difficulty, tachypnea, diaphoresis, hepatomegaly, and growth. Class I represents asymptomatic patients, Class II indicates mild symptoms with exertion
Pediatric LV Mass (LVM) and Z-score: Explanation and Clinical Context Left ventricular mass (LVM) estimated from M-mode echocardiography is commonly calculated using the Devereux formula (implemented above). Because children vary widely in body size, LVM must be normalized for body size; common approaches include indexing to height (allometric index, e.g., height^2.7), indexing to body surface area (BSA), or using ce
Pediatric Myocarditis Severity Index: Explanation and Clinical Context The Pediatric Myocarditis Severity Index (PMSI) is a clinical tool designed to stratify the risk and predict outcomes in children with acute myocarditis. It incorporates key variables including age, heart rate, left ventricular ejection fraction (LVEF), serum troponin I levels, and BNP levels to provide an integrated risk score. A higher PMSI scor
Pulmonary Valve Annulus (PVA) Z-score — explanation and clinical context This calculator implements the regression equations published by Pettersen et al. (J Am Soc Echocardiogr 2008) to compute a z-score for the pulmonary valve annulus relative to body size. Pettersen and colleagues derived nonlinear polynomial regression models on the natural-log transformed echocardiographic measurements against body surface area
Pulmonary Vascular Resistance Calculator Explanation and Clinical Context Pulmonary vascular resistance describes the afterload that the right ventricle must overcome to eject blood into the pulmonary circulation. It is derived from a hemodynamic relationship that integrates pressure gradients across the pulmonary vasculature and the magnitude of pulmonary blood flow. PVR reflects the degree of vasoconstriction, remo
Pulmonary-to-Systemic Flow Ratio (Qp/Qs): Explanation and Clinical Context The Pulmonary-to-Systemic Flow Ratio (Qp/Qs) is a hemodynamic index derived from the Fick principle that quantifies the relative blood flow between the pulmonary and systemic circulations. It is essential for the assessment of cardiac shunts such as atrial septal defect (ASD), ventricular septal defect (VSD), and patent ductus arteriosus (PDA)
RACHS-1 (Risk Adjustment in Congenital Heart Surgery): Explanation and clinical context The RACHS-1 method groups pediatric congenital heart surgical procedures into six categories (1–6) of increasing expected operative risk to allow comparisons of in-hospital mortality between case mixes, institutions, or time periods. RACHS-1 was developed by consensus using the Pediatric Cardiac Care Consortium (PCCC) dataset and
RCPCH Myocarditis Prognosis Score: Explanation and Clinical Context The RCPCH Myocarditis Prognosis Score is a clinical risk tool developed to estimate the probability of adverse outcomes, including death or requirement for mechanical circulatory support, in children presenting with acute myocarditis. It uses variables available at presentation, including age, heart rate, systolic blood pressure, left ventricular eje
Rp/Rs Ratio (Pulmonary/Systemic Resistance): Explanation and Clinical Context The Rp/Rs ratio represents the relative resistance of the pulmonary circulation (PVR) to the systemic circulation (SVR). It is calculated as the pulmonary vascular resistance divided by the systemic vascular resistance, providing insight into the balance between pulmonary and systemic vascular loads. A normal Rp/Rs ratio is typically less t
RVEDd Z-score: Explanation and Clinical Context The RVEDd Z-score expresses the deviation of measured right ventricular end-diastolic dimension (in mm) from the predicted mean value, normalized by the standard deviation (SD) of the reference population. A Z-score of 0 means that the measurement equals the population mean; positive values indicate enlargement relative to body size, negative values indicate smaller dim
Shunt Fraction Index (Qp:Qs Ratio): Explanation and Clinical Context The Qp:Qs ratio, also known as the Shunt Fraction Index, is used to quantify the magnitude of left-to-right cardiac shunts. It is defined as the ratio of pulmonary blood flow (Qp) to systemic blood flow (Qs). A Qp:Qs ratio of 1 indicates no shunt, while values above 1 indicate a left-to-right shunt, with higher values reflecting larger shunts. Clini
STAT Mortality Categories (STS–EACTS): Explanation and clinical context The STAT (Society of Thoracic Surgeons – European Association for Cardio-Thoracic Surgery) Mortality Scores and Categories are an empirically derived, procedure-based stratification system for congenital and pediatric cardiac surgery. Each index operation is assigned a numeric STAT score (range ~0.1–5.0) derived from large STS/EACTS registry data
— explanation and clinical context The STS Congenital Heart Surgery Database (CHSD) mortality risk approach stratifies operative risk primarily by procedure complexity (the STAT mortality category) and then adjusts for multiple patient-level factors (age group, weight/low birthweight, prior cardiothoracic operations, genetic/chromosomal abnormalities, non-cardiac congenital anomalies, multiple preoperative risk facto
: Explanation and Clinical Context This tool estimates the probability of an adverse surgical outcome (e.g., mortality or major complication) after repair of transposition of the great arteries, based on key preoperative and intraoperative variables (age at surgery, ventricular function, presence of a VSD, complexity of coronary anatomy, ischemic time). In this sample implementation, a logistic regression model is as
TOF Risk Stratification Index (RVOT Gradient + Anatomy): Explanation and Clinical Context The TOF Risk Stratification Index estimates post-operative risk in patients with Tetralogy of Fallot (TOF) based on right ventricular outflow tract (RVOT) gradient and anatomical complexity. RVOT gradient reflects the severity of right ventricular obstruction, while anatomical complexity accounts for coronary artery anomalies, p
VSD Size Ratio Index: Explanation and Clinical Context The Ventricular Septal Defect (VSD) Size Ratio Index is calculated as the ratio of the VSD diameter to the aortic annulus diameter measured on echocardiography. This ratio provides a normalized, dimensionless parameter that allows for interindividual comparison regardless of patient size or age. A VSD/Aortic diameter ratio below 0.3 typically indicates a small de
Z-score Coronary Origin (pediatric database): Explanation and Clinical Context This calculator normalizes measured coronary internal diameters to body size using a log-linear z-score model widely used in pediatric echocardiography. The typical modelling approach (used by Dallaire & Dahdah and others) fits a regression of the natural logarithm of coronary diameter (mm) against the natural logarithm of body surface are
Z-score Pulmonary Artery (CHD Reference Model): Explanation and Clinical Context Z-score of the pulmonary artery is a dimensionless value that expresses how many standard deviations an individual’s pulmonary artery diameter deviates from the predicted mean for a given body size. In patients with congenital heart disease (CHD), accurate assessment of pulmonary artery size is crucial for surgical planning, prosthesis s