Final answer:
The sensitivity and specificity of stress echocardiography in evaluating LV systolic dysfunction are linked to cardiac physiology measurements like SV, EF, and contractility, along with factors like preload, afterload, and inotropic influences.
Step-by-step explanation:
To assess the sensitivity and specificity of stress echocardiography regarding significant resting left ventricular (LV) systolic dysfunction, it's important to understand some basic cardiac physiology parameters such as stroke volume (SV) and ejection fraction (EF). SV is calculated by the difference between end diastolic volume (EDV) and end systolic volume (ESV): SV = EDV - ESV. Ejection fraction is then determined by dividing SV by EDV and is expressed as a percentage, typically ranging from 55-70 percent in a healthy heart.
Factors affecting heart contractility, and therefore SV and cardiac output, include preload (ventricular stretch prior to contraction), contractility (force of the contraction itself), and afterload (resistance against which the ventricles must pump). Positive inotropic factors enhance contractility, leading to an increased SV and a reduced ESV, while negative inotropic factors have the opposite effect. Understanding these parameters can further elucidate the cardiac response to alterations in blood flow and pressure.