Theoretical Analysis of the Hemodynamic Variables During Sustained Mechanical Alternans: Effect of Variations in Ventricular Filling Volume
✍ Scribed by David Adler
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 473 KB
- Volume
- 163
- Category
- Article
- ISSN
- 0022-5193
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✦ Synopsis
A comprehensive discrete analysis of the hemodynamic variables during sustained mechanical alternans (SMA) shows that these variables are governed by simple mathematical relations. The analysis shows that the value of the slope created by the two alternating beats on the stroke volume-end diastolic ( (S V-E D V) ) plane is (\bar{\gamma}=(\mu-1) .(1+\beta) /(\mu-\beta)), where (\mu=S V_{s} / S V_{w}, S V_{s}) and (S V_{w}) denote the strong and weak beats, respectively, in the presence of one contractile state of the beating heart, and the beats associated with the higher and lower contractile states, respectively, in the presence of two alternating contractile states; (\beta=F V_{s} / F V_{w}, F V_{s}) and (F V_{w}) are the filling volumes following (S V_{s}) and (S V_{w}), respectively. Two separate analyses show that this equation is valid, whether SMA is exhibited in the presence of one or two contractile states, and irrespective of the (S V-E D V) functional relationship. A criterion based on this slope, in terms of measurable parameters, is described to determine if SMA is caused by variations in EDV and (F V). This comprehensive quantitative analysis enables a complete classification of the various types of SMA into subcategories with well-defined features. In particular, this analysis confirms former interesting theoretical consequence that when (F V) is constant, (\bar{\gamma}) attains the value of 2 , independently of the value of (\mu) or any other factor.