1,329 calculators and references across 60 specialties, with each tool type shown up front.
Risky Mitral Valve (Echo-based risk stratification): Explanation and Clinical Context The Risky Mitral Valve concept uses echocardiographic assessment to identify mitral valve disease patients at high risk of complications during or after intervention. Key echocardiographic parameters include leaflet morphology (thickening, calcification, restricted motion), annular dilation, subvalvular apparatus abnormalities, mitr
Right and Left Heart Catheterization Calculator: Clinical explanation and context Overview Right and left heart catheterization is a procedure performed to measure intracardiac pressures and blood oxygen saturations for the purpose of calculating pulmonary and systemic blood flows and resistances. The calculations in this tool use the Fick principle to estimate pulmonary flow and systemic flow and then derive resista
Rockall Upper GI Bleeding Score Explanation and Clinical Context The Rockall score estimates risk of adverse outcome after an acute upper gastrointestinal bleeding episode. It combines three clinical variables available at admission that form the pre endoscopic score and two endoscopic variables that produce the complete score. Age contributes up to two points depending on age group. Hemodynamic status is captured by
— explanation and context This page presents an experimental composite index adapted to reflect the primary predictors and outcomes described in ROCKET-AF and its heart-failure subgroup analyses. The ROCKET-AF trial (rivaroxaban vs warfarin) enrolled a high-risk atrial fibrillation population and reported subgroup analyses examining outcomes among patients with heart failure, demonstrating that heart failure patients
Romhilt–Estes Point-Score System: Explanation and Clinical Context The Romhilt–Estes (R-E) point-score system is a composite electrocardiographic method developed to improve ECG detection of left ventricular hypertrophy by combining six ECG features (P-terminal force in V1, high QRS voltages, ST-T changes consistent with “strain”, left axis deviation, prolonged QRS duration, and delayed intrinsicoid deflection). Each
: Explanation and Clinical Context The ROPAC Registry Predictive Model, endorsed by the 2020 ESC Guidelines, provides an evidence-based estimate of 1-year mortality risk in patients with pregnancy-associated cardiovascular conditions or pre-existing heart disease. This logistic regression model incorporates patient age, NYHA functional class, left ventricular ejection fraction (LVEF), history of heart failure, presen
Explanation and Clinical Context This tool is intended for patients who have experienced out of hospital or in hospital cardiac arrest have achieved return of spontaneous circulation and subsequently are found to have an electrocardiographic pattern consistent with ST segment elevation myocardial infarction. The twenty twenty five American acute coronary syndromes guideline emphasizes that patients with return of spo
SpO2 FiO2 Percentage Respiratory Rate ROX Index Explanation and Clinical Context The ROX Index is a clinical tool used to predict the success of high flow nasal cannula therapy in patients with acute hypoxemic respiratory failure. It is calculated using the ratio of peripheral oxygen saturation to fraction of inspired oxygen divided by respiratory rate. A higher ROX Index reflects better oxygenation efficiency and lo
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
Clinical reference for RRI Mortality Association Calculator, with practical context for use alongside current guidance and professional judgment.
RSBI Mechanical Ventilation Weaning Index Explanation and Clinical Context The rapid shallow breathing index known as RSBI is defined as the ratio of respiratory frequency to tidal volume in liters. It is calculated as respiratory rate divided by tidal volume in liters during spontaneous breathing conditions. RSBI measures the pattern of breathing and reflects the balance between respiratory drive and the ability of
Rutherford Classification: Explanation and Clinical Context Rutherford Classification is a widely accepted system for grading the severity of peripheral arterial disease (PAD). It stratifies patients from stage 0 (asymptomatic) to stage 6 (major tissue loss), incorporating claudication severity, presence of rest pain, and degree of tissue loss. Stage 0 represents no symptoms, stages 1-3 correspond to increasing sever
RV 2C (Right Ventricular Two-Chamber) RV 2C (Right Ventricular Two-Chamber) RA : Right atrium, RV : Right ventricle, SVC : Superior vena cava, TV : Tricuspid valve.
Right Ventricular Fractional Area Change (FAC): definition, clinical meaning and evidence-based context RV FAC quantifies global right ventricular systolic function from an RV-focused apical four-chamber view by tracing the RV endocardial border in end-diastole and end-systole and applying the equation: FAC (%) = 100 × (RV end-diastolic area − RV end-systolic area) / RV end-diastolic area. The American Society of Ech
Clinical reference for RV Global Longitudinal Strain Rvgls Risk Model Pulmonary Hypertension Outcomes, with practical context for use alongside current guidance and professional judgment.
Right Ventricular (RV) Involvement Index: Explanation and Clinical Context The RV Involvement Index is a composite echocardiographic score designed to quantify right ventricular dysfunction by integrating three key parameters: RV fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), and the right ventricular myocardial performance index (RV MPI). This index provides a continuous measure of
Clinical reference for RV PA Coupling Ees Ea Surrogate Index Calculator, with practical context for use alongside current guidance and professional judgment.
Clinical reference for RV PA Coupling Index Echo Based Calculator, with practical context for use alongside current guidance and professional judgment.
Clinical reference for RV Pressure Aortic Pressure Ratio Pah Threshold Calculator, with practical context for use alongside current guidance and professional judgment.
Clinical reference for RV Strain Prognostic Index Echo Based Calculator, with practical context for use alongside current guidance and professional judgment.
Right Ventricle to Left Ventricle (RV/LV) Ratio on Echocardiography: Explanation and Clinical Context The RV/LV ratio is a measurement derived from echocardiography that compares the end-diastolic diameter of the right ventricle (RV) to the left ventricle (LV). It is widely used to assess right ventricular dilation, which can occur in conditions such as acute pulmonary embolism, pulmonary hypertension, right heart fa
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
RVOT VTI Cardiac Output Estimation in Pulmonary Hypertension: Explanation and Clinical Context RVOT VTI (Right Ventricular Outflow Tract Velocity Time Integral) is a Doppler echocardiography parameter used to estimate stroke volume and cardiac output, particularly in patients with pulmonary hypertension (PH). The stroke volume is calculated as the product of the RVOT cross-sectional area and the VTI, then multiplied
Serum Albumin Ascitic Albumin Serum Ascites Albumin Gradient SAAG Explanation and Clinical Context SAAG represents the difference between serum albumin concentration and ascitic albumin concentration. It is a validated method to classify the underlying mechanism of ascites formation and to guide diagnostic reasoning. A value of one point one g per dL or more indicates portal hypertension related etiologies because th
Signal-Averaged ECG (SAECG) Abnormality Index: Explanation and Clinical Context SAECG is a specialized electrocardiographic technique used to detect subtle abnormalities in ventricular depolarization that are not visible on standard ECG. The SAECG Abnormality Index quantifies risk for ventricular arrhythmias by scoring three primary parameters: filtered QRS duration, low amplitude signal duration, and root mean squar
SAFE-TAVR Score: Explanation and Clinical Context The SAFE-TAVR Score is a clinical tool designed to assess the risk of pericardial effusion or cardiac tamponade following Transcatheter Aortic Valve Replacement (TAVR). It incorporates patient-specific factors such as age, sex, presence of chronic kidney disease, hypertension, ventricular function, and access site to stratify risk. This score aids clinicians in identi
Spatial Angle Index (SAI QRST): Explanation and Clinical Context SAI QRST is a quantitative ECG-derived index that measures the spatial angle between the QRS complex and T wave vectors in three-dimensional space. It reflects the degree of heterogeneity in ventricular depolarization and repolarization. Higher values of SAI QRST indicate greater electrical instability and are associated with increased risk of ventricul
: Explanation and Clinical Context This estimator quantifies the potential impact of reducing average daily salt consumption on population-level blood pressure and cardiovascular risk. Excessive sodium intake is a major modifiable determinant of hypertension, which in turn is a leading cause of stroke, ischemic heart disease, and chronic kidney disease. Meta-analyses have consistently demonstrated that for every 1 gr
SAMe-TT₂R₂ Score: Explanation and Clinical Context The SAMe-TT₂R₂ score is a validated clinical tool to predict the quality of warfarin anticoagulation control in patients with atrial fibrillation. It integrates demographic and clinical factors including sex, age, comorbidities, concomitant interacting drugs, tobacco use, and race. A score of 0–2 predicts likely good anticoagulation control (time in therapeutic range
Simplified Acute Physiology Score II (SAPS II): Explanation and Clinical Context SAPS II is a validated intensive care unit (ICU) mortality prediction model designed to estimate the probability of hospital mortality based on physiological variables measured during the first 24 hours of ICU admission. It incorporates 17 parameters: 12 physiological variables, age, type of admission, and three underlying disease variab
Simplified Acute Physiology Score II SAPS II Explanation and Clinical Context The SAPS II score is a validated severity of illness classification intended to estimate risk of hospital death for adult patients admitted to intensive care units using the worst values collected in the first 24 hours after admission. The score aggregates points from 15 items including age type of admission heart rate systolic blood pressu
Sarcoidosis Cardiac Involvement Score (SCIS): Explanation and Clinical Context The SCIS is a scoring system designed to assess the likelihood of cardiac involvement in patients with sarcoidosis. It incorporates clinical and imaging parameters to stratify risk and guide management decisions. A higher score indicates a greater likelihood of cardiac involvement and may necessitate more aggressive monitoring and treatmen
ECG Pattern -- choose -- Normal Nonspecific repolarization changes Typical for myocarditis (diffuse ST-T changes / PR depression / new AV block / ventricular arrhythmia) CMR (2018 Lake Louise Criteria) -- choose -- Positive Equivocal / indeterminate Negative Not performed Days from Symptom Onset to CMR (leave blank if CMR not done) SARS-CoV-2 Myocarditis: Explanation and Clinical Context In patients with COVID-19, my
SAVE Post-MI LV Dysfunction Prognostic Score — Explanation and Clinical Context This calculator estimates the prognosis of patients after myocardial infarction (MI) with left ventricular (LV) systolic dysfunction, using key clinical and laboratory parameters repeatedly shown to correlate with mortality and adverse remodeling. The variables include age, LVEF, Killip class, renal function, systolic blood pressure, hear
SAVE Score (Survival After Veno-Arterial ECMO): Explanation and Clinical Context The SAVE score is a validated tool designed to predict in-hospital mortality for adult patients undergoing VA-ECMO for refractory cardiogenic shock. It incorporates multiple pre-ECMO variables, including age, body weight, underlying diagnosis, pre-ECMO organ failures, serum bicarbonate, peak inspiratory pressure, and duration of mechanic
SC (Subcostal View) SC 4C (Subcostal 4 Chamber) 4C : 4 chamber, IAS : Interatrial septum, IVS : Interventricular septum, LA : Left atrium, LV : Left ventricle, MV : Mitral valve, RA : Right atrium, RV : Right ventricle, SC : Subcostal, TV : Tricuspid valve. SC (Superior Vena Cava) IVC : Inferior vena cava, RA : Right atrium, SC : Subcostal, SVC : Superior vena cava. SC (Long Axis IVC) IVC : Inferior vena cava, RA : R
SCAI Shock Stages: Explanation and Clinical Context The Society for Cardiovascular Angiography and Interventions (SCAI) shock stages provide a standardized framework for classifying the severity of cardiogenic shock from Stage A (At risk) to Stage E (Extremis). Stage A includes patients at risk but without hypoperfusion. Stage B shows early signs of shock without organ dysfunction. Stage C represents classic cardioge
: Explanation and Clinical Context The Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) evaluated the role of implantable cardioverter-defibrillator (ICD) therapy in patients with heart failure and reduced ejection fraction (HFrEF). The study enrolled patients with ischemic or nonischemic cardiomyopathy, NYHA class II–III, and LVEF ≤35%. This calculator provides an approximate estimation of the 3-year all-cause
SCD-HeFT Risk Model: Explanation and Clinical Context The SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) Risk Model estimates 5-year mortality risk in patients with chronic heart failure and reduced ejection fraction. The model is derived from a multivariable Cox proportional hazards analysis of the SCD-HeFT trial population, incorporating age, sex, NYHA class, left ventricular ejection fraction (LVEF), ische
SCD-HeFT Risk Model: Explanation and Clinical Context The SCD-HeFT Risk Model estimates the 5-year risk of all-cause mortality in patients with heart failure with reduced ejection fraction (HFrEF) who are candidates for implantable cardioverter-defibrillator (ICD) therapy. The model uses clinical variables available at baseline, including age, NYHA functional class, left ventricular ejection fraction (LVEF), presence
Schwartz Score for Long QT Syndrome: Explanation and Clinical Context The Schwartz Score is a validated diagnostic tool to assess the probability of congenital Long QT Syndrome (LQTS). It incorporates electrocardiographic, clinical, and family history features including QTc interval, history of syncope, congenital deafness, and family history of sudden cardiac death or LQTS. Points are assigned based on QTc duration,
SCN5A Variant Pathogenicity Index: Explanation and Clinical Context The SCN5A Variant Pathogenicity Index is a clinically validated tool to estimate the likelihood that a given SCN5A gene variant contributes to arrhythmia disorders, including Brugada Syndrome and Long QT Syndrome type 3. It integrates multiple lines of evidence: variant type (missense, nonsense, frameshift, splice-site, in-frame indel), functional st
SCORE-Hyper Model: Explanation and Clinical Context SCORE-Hyper is a validated tool designed to estimate the 10-year risk of fatal cardiovascular events in patients with hypertension. It considers key variables including age, sex, systolic blood pressure, total cholesterol, and smoking status. The model incorporates coefficients specifically derived from hypertensive populations, providing more precise risk predictio
About SCORE2 (European Society of Cardiology, 2021): SCORE2 is the updated cardiovascular risk estimation model replacing the original SCORE (2003). It predicts the 10-year risk of both fatal and non-fatal cardiovascular events in apparently healthy adults aged 40-69 years. Developed using pooled European cohort data (n = > 600,000), it includes sex, age, smoking status, systolic blood pressure, and lipid profile (to
SCORED Trial (Sotagliflozin) Risk Index — explanation and clinical context this calculator uses a trial-derived risk estimator based on SCORED trial aggregate results. SCORED enrolled adults with type 2 diabetes and chronic kidney disease and reported a primary composite event rate in the placebo arm of approximately 7.5 events per 100 patient-years (≈7.5% per year) and an estimated hazard ratio of 0.74 for the
SCORTEN Severity of Illness Score for Toxic Epidermal Necrolysis SCORTEN is a validated prognostic index intended to estimate the probability of death in patients with Stevens Johnson syndrome and toxic epidermal necrolysis when assessed within the first 24 hours of admission. The score comprises seven independent variables each scored as one point if present. These variables are age 40 years or older, presence of ac
Screening ECG Yield in Primary Care: Explanation and Clinical Context The Screening ECG Yield in Primary Care calculator estimates the Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of routine electrocardiographic (ECG) screening programs based on population disease prevalence and test characteristics (sensitivity and specificity). PPV and NPV are essential for evaluating the clinical yield of sc
Seattle Angina Questionnaire (SAQ): Explanation and Clinical Context The SAQ is a patient-reported outcome measure specifically developed to quantify the impact of angina on patients with coronary artery disease. It assesses five domains: Physical Limitation, Angina Stability, Angina Frequency, Treatment Satisfaction, and Quality of Life, each scored from 0 (worst) to 100 (best). Higher scores indicate better patient
Seattle Heart Failure Model (SHFM): Explanation and Clinical Context The SHFM is a validated multivariable model to estimate mortality risk in patients with chronic heart failure based on clinical, laboratory, and treatment variables. It was developed using data from the PRAISE I cohort and externally validated in multiple populations. The model calculates a risk score (SHFM Score) using regression coefficients appli
Seattle Heart Failure Model (SHFM): Explanation and Clinical Context The SHFM is a validated multivariable model to estimate mortality risk in patients with chronic heart failure based on clinical, laboratory, and treatment variables. It was developed using data from the PRAISE I cohort and externally validated in multiple populations. The model calculates a risk score (SHFM Score) using regression coefficients appli
Seattle Proportional Risk Model (SPRM): Explanation and Clinical Context The SPRM is a prognostic tool designed to estimate the proportion of sudden death among all-cause mortality in patients with heart failure and reduced ejection fraction (EF < 35%). Developed from a cohort of 9,885 patients with 2,552 deaths, the model identifies key clinical variables associated with a higher likelihood of sudden death. These in
Explanation and Clinical Context This tool provides an estimation of mortality severity in patients presenting with sepsis by integrating several physiologic and biochemical variables that are strongly associated with adverse outcomes. Serum lactate reflects cellular hypoperfusion and metabolic stress. Mean arterial pressure reflects circulatory stability and correlates with the adequacy of organ perfusion. Creatinin
Sepsis-Related Myocardial Dysfunction (SIMD) Severity Index Enter values available at bedside/ICU admission or within the first 24 hours. Use absolute (positive) value for GLS (e.g., 18 = normal strain ~ −18%). Troponin input is expressed as multiple of your lab’s upper limit of normal (ULN). Norepinephrine dose is in µg/kg/min. Sepsis-Related Myocardial Dysfunction (SIMD): Explanation and Clinical Context SIMD (ofte
Explanation and Clinical Context This tool translates guidance from the twenty twenty five American College of Cardiology and American Heart Association guideline for acute coronary syndromes into a structured approach to repeat twelve lead electrocardiograms in patients with suspected or confirmed acute coronary syndrome. The guideline recommends acquisition and interpretation of an ECG within ten minutes of first m
Serial Troponin Trajectory Interpretation. Comprehensive Explanation and Clinical Context Serial measurement of high sensitivity cardiac troponin plays a pivotal role in the diagnosis of acute coronary syndrome. The 2025 AHA ACS guideline emphasizes rapid rule in and rule out assessment using baseline and 1 to 2 hour repeat hs troponin values combined with clinical history and ECG findings. Serial trajectory interpre
Serum Lactate Mortality Index (post-CPB): Explanation and Clinical Context The Serum Lactate Mortality Index (SLMI) is a prognostic tool used to estimate the risk of postoperative mortality in patients after cardiopulmonary bypass (CPB). It is calculated by multiplying peak serum lactate levels (mmol/L) by the time elapsed since CPB (hours). Elevated lactate levels reflect impaired tissue perfusion and oxygen deliver
Sodium Na mEqL Glucose mgdL BUN mgdL Explanation and Clinical Context Serum osmolality reflects the concentration of dissolved particles in plasma and provides an essential window into the body water balance. The major contributors to serum osmolality are sodium glucose and blood urea nitrogen which form the basis of the widely used calculated osmolality formula. Normal serum osmolality ranges from two hundred sevent
Left atrium (Size) Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI (2015) Left atrium (Volume) Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI (2015) Right atrium (Size) Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI (
Clinical reference for Sex Hormone Cardiac Risk Interaction Index, with practical context for use alongside current guidance and professional judgment.
SF-36 Physical Function Domain: Explanation and Clinical Context The SF-36 Physical Function (PF) domain evaluates the extent to which health limits physical activities, from vigorous activities such as running or lifting heavy objects to basic self-care tasks. It consists of 10 items, each scored on a Likert scale. The total raw score is converted to a 0–100 scale, where higher scores indicate better physical functi