Tan, Haiming, authorDasi, Lakshimi Prasad, advisorPopat, Ketul, committee memberOrton, Chris, committee member2007-01-032007-01-032013http://hdl.handle.net/10217/80320Heart disease is the #1 cause of death in the United States with congestive heart failure (CHF) being a leading component. Load induced CHF, i.e. CHF in response to chronic pressure or volume overload, may be classified either as systolic failure or diastolic failure, depending on the failure mode of the pumping chamber. To assess the severity of systolic failure, there exist clinical indices that quantify chamber contractility, namely: ejection fraction, (dP/dt), Emax (related to the rate of pressure rise in the pumping chamber), and Emax (related to the time-dependent elastance property of the ventricle). Unfortunately, these indices are plagued with limitations due to inherent load dependence or difficulty in clinical implementation. Indices to assess severity of diastolic failure are also limited due to load dependence. The goal of this research is to present (1) a new framework that defines a new contractility index, Tmax, and ventricular compliance 'a', based on Frank-Starling concepts that can be easily applied to human catheterization data, and (2) discusses preliminary findings in patients at various stages of valve disease. A lumped parameter model of the pumping ventricle was constructed utilizing the basic principles of the Frank-Startling law. The systemic circulation was modeled as a three element windkessel block for the arterial and venous elements. Based on the Frank-Starling curve, the new contractility index, Tmax and ventricular compliance 'a' were defined. Simulations were conducted to validate the load independence of Tmax and a computed from a novel technique based on measurements corresponding to the iso-volumetric contraction phase. Recovered Tmax and 'a' depicted load independence and deviated only a few % points from their true values. The new technique was implemented to establish the baseline Tmax and 'a' in normal human subjects from a retrospective meta-data analysis of published cardiac catheterization data. In addition, Tmax and 'a' was quantified in 12 patients with a prognosis of a mix of systolic and diastolic ventricular failure. Statistical analysis showed that Tmax was significantly different between the normal subjects group and systolic failure group (p<0.019) which implies that a decrease in Tmax indeed predicts impending systolic dysfunction. Analysis of human data also shows that the ventricular compliance index 'a' is significantly different between the normal subjects and concentric hypertrophy (p < 0.001). This research has presented a novel technique to recover load independent measures of contractility and ventricular compliance from standard cardiac catheterization data.born digitalmasters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.contractilityventricular stiffnesslumped parameter modellingfrank-starlingText