App: Single Ventricle Circulation
Developer: Tim Conover
Genres: Education, Medical

This app presents a model of circulation throughout the three stages of surgical palliation for patients with single ventricle physiology, known as the Fontan sequence.  An educational tool designed for medical students and anyone interested in congenital heart defects, the app allows the user to experiment with several different common surgical procedures and medical treatments, to observe the effects on clinical measures like blood pressures and oxygen delivery both at rest and during exercise, and to predict immediate post-surgical outcomes. The app displays both tabular results, and time-based blood pressure and flow waveforms and ventricular pressure-volume loops.

This app accompanies our JTCVS paper(1), which describes the circulation models used, abbreviations and settings. The paper includes details of the model mechanics, and a partial validation of model outputs vs. clinical measurements from 47 patients. This is the hand-held device app mentioned in that paper. The app provides default values for the circulation, which the user can can be customize to investigate clinical situations or patient-specific predictions. Details on the basis of the circulation model are cited in the JTCVS paper (1). 

(1) Conover, T., Hlavacek, A.M., Migliavacca, F. et al. An interactive simulation tool for patient-specific clinical decision support in single ventricle physiology. J Thorac Cardiovasc Surg. 2018; 155: 712–721

Release notes:
In Version 1.0 the interface as been completely overhauled for Universal compatibility to run on both iPad and iPhone.  This version also runs on Apple Silicon Macs.  There is also a version for Intel Macs running Mac OS 10.15+.
• New color scheme also supports Dark Mode.
• Minimum required iOS 12.3, still supports original iPad Air and iPhone 5S.  Future versions will require iOS 13+.
• User needs to "agree" to the disclaimer only once, on the first launch after install.
• New user's manual pages on the Single Ventricle Circulation Home web site.
• iPhone version has pinch-zooming feature for best visibility of plots.
• iPhone version has a scroll-locking mechanism on the inputs and results tables to improve readability.
• Updated TCPC pump model using new H-Q vs. RPM data.  Also, new calculation of caval pressure and TCPC gradient for results, and a new visual indicator of the TCPC pump impeller.
• New, more-consistent treatment of collaterals and coarctation in modified runs retaining baseline resistances.
• Some corrections of the exercise model to match the Kung model as-published. 
• Install with confidence - user cases entered in the previous version are preserved on your device (unless, of course, you do a clean install).