Diastolic Function
Red Blood Cells
Respiratory Function
Figure Description - Illustration of the heart by Iryna Savinova
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All About Diastolic Function
Classically, cardiac function is evaluated by how well the heart contracts – systolic function. This is, at least in part, also dependent upon how the heart relaxes – diastolic function. Diastole is divided into two processes: active relaxation in early diastole and passive filling in late diastole. The active relaxation phase, reflecting the energy-consuming process of diastole, is dependent on adenosine triphosphate (ATP) availability and the clearance of intracellular calcium levels, thereby allowing actin and myosin to dissociate and relaxation to occur. The filling phase of diastole is largely dependent upon the stiffness of the heart, influenced by the quantity of extracellular matrix in the myocardium. The two processes of diastole are measured by invasive hemodynamics, which is the gold standard for evaluating cardiac function.
In many cardiovascular diseases, diastolic dysfunction precedes left ventricle remodeling and systolic dysfunction. Yet, existing therapies target systolic dysfunction, while there are no treatments or management strategies for diastolic dysfunction. The rising incidence of heart failure with preserved ejection fraction (HFpEF) – accounting for ~50% of all heart failure cases – and ongoing search for a preclinical model to recapitulate the patient syndrome has contributed to a surge in researching diastolic function. A major focus in the Simpson Lab is assessing diastolic dysfunction in various physiological and pathological states, such as aging, sex-differences, and models of heart failure (e.g., myocardial infarction). For more information on how to evaluate diastolic function by invasive hemodynamics, check out the links to our review paper and podcast below:
Ogilvie LM, Edgett BA, Huber JS, Platt MJ, Eberl HJ, Lutchmedial S, Brunt KR, Simpson JA.
(2020) Hemodynamic assessment of diastolic function for experimental models. Am J Physiol Heart Circ Physiol. 318: H1139-H1158. https://doi.org/10.1152/ajpheart.00705.2019.
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https://ajpheart.podbean.com/e/assessment-of-diastolic-function/
Figure Description - Red blood cells
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Hypoxia (i.e., impaired oxygen delivery) is a common feature of many acute and chronic diseases. It reduces the quality of life and increases morbidity, mortality, and hospitalizations in patients, especially those with heart failure. Therefore, under normal and hypoxic conditions, we use genetically modified animal models and cell culture assays to study novel cardiac protein hormones and investigate their regulation and functional effects in vitro and in vivo. This research will help to identify endogenous pathways that will ultimately lead to new targets for the treatment of heart failure.
Figure Description - Illustration of the lungs