"•CathCalc
•Michael R. Nihill MD
Information obtained at Cardiac catheterization plays an important role in the diagnosis and
management of patients with congenital and acquired heart disease which is useful for Adult and
Pediatric Cardiologists, Cardiology fellows, Neonatologists &. Pulmonologists.
CathCalc is a hemodynamic calculator which calculates basic and advanced hemodynamics using the Fick
principle.
The output is systemic & pulmonary blood flow and ratios, (Qs, Qp, Qp:Qs), Effective pulmonary blood
flow (QeP), systemic & pulmonary resistance and ratios (Rs, Rp & Rp:Rs)
CathCalc also calculate shunts at more than one level, eg an ASD, a VSD & PDA. giving the results as % of
pulmonary blood flow & as L/min/M2.
There is also a calculation of the “Primary Pulmonary Hypertension index number” which is used to
calculate the predicted survival for 1, 2 & 3 years for patients with primary pulmonary hypertension,
based on the PA pressure, Right atrial pressure & cardiac output.
Using the patient name & cath date, several cath conditions or cath dates can be saved &
compared.
Data input:
The Patient information window shows a list of patients in the database. There is a “+” button it
enter a new patient name, date & condition.
For a patient already in the database, press the arrow next to the patient name and a new window
allows the user to view the patient’s history or enter a new condition.
After entering data on each window, there is a “next” button which shows the next window for
data entry; On the last window there is a “done” button which starts the calculations.
To review or edit the data windows press the”back” button
1. Using body weight (Kg) & height (cm), the program calculates Body Surface Area (BSA M2),
Body mass Index (BMI) and Oxygen consumption (VO2 ml/min/M2)
2. Hemoglobin (Hb g%) Calculates Oxygen content (O2Cont ml %), Oxygen Capacity (O2Cap
ml) & Optimal Hemoglobin for desaturated patients (OptHb g%)
Samuel S. Gidding, MD, James A. Stockman III, MD Erythropoietin in cyanotic heart disease.
American Heart Journal Volume 116, Issue 1, Part 1, July 1988, Pages 128–132
3. Saturation data (%): The user selects values to add to the Hemodynamics table for:
1. Mixed venous saturation
2. Systemic artery saturation
3. Pulmonary Venous Saturation
4. Pulmonary artery saturation
From this data Basic hemodynamic calculations can be made using the Fick principle
4. If Oxygen or a drug is administered, the pO2 (mmHg) data can be entered at various sites to
adjust the Oxygen content values.
5. Mean pressure data (mmHg) is added to the various sites
Basic & Advanced Hemodynamics
Systemic Blood Flow (Qs L/min/M2)
Pulmonary Blood Flow (Qp L/min/M2)
Ratio of Pulmonary to Systemic Blood Flow (Qp:Qs)
Effective Pulmonary Blood Flow (Qep L/min/M2)
The left to right shunt (L->R L/min/M2) & Right to left shunt (R->L L/min/M2)
Pulmonary & Systemic resistance (Rp & Rs U.M2), Resistance ratios (Rp:Rs) and Total
pulmonary Resistance (TPR U.M2)
Advanced Hemodynamics
If Saturation data is also entered for the Right atrium(RA) & Right Ventricle (RV), calculations
can be made of the amount of shunting at 3 levels, (ASD, VSD & PDA) as a % of the total
pulmonary blood flow and in L/min/M2.
Advanced Hemodynamics: Pulmonary Hypertension Survival predictor
Using Pulmonary artery mean pressure, Right atrial pressure and Cardiac output, a "Pulmonary
artery hypertension number” is calculated. For simplified use, Cardiac output (CI), right atrial
pressure Rap) & PA pressure can be entered for a quick calculation.
Based on the NIH PHT registry, a prediction of survival for 1, 2 & 3 years can be made.