Basics of hemodynamic evaluation – 3

Basics of hemodynamic evaluation – 3 While evaluating intracardiac shunt lesions by cardiac catheterization, an easy way is to look at the step up or step down in the oxygen saturation between two chambers. For example, in case of left to right shunts, step up is noted between superior vena cava (SVC) and right atrium in case of atrial septal defect (ASD). Among the atrial septal defects, step up is noted in high right atrium for sinus venosus ASD, mid right atrium for secundum ASD and low right atrium for primum ASD. Step up from right atrium to right ventricle is noted in ventricular septal defect. In case of patent ductus arteriosus, step up is noted at the pulmonary artery (PA) level. When there is reversal of shunt due to severe pulmonary hypertension, step down is seen in these chambers. While sampling the right atrium for estimation of oxygen saturation, catheter should be directed laterally to prevent direct sampling from the three different streams with highly varying oxygen saturation (the vena cavae and coronary sinus). For the same reason, minimum level of step up considered as significant at atrial level is 10% while it is only 5% at ventricular and great artery level. If multiple sets of samples show consistent step up, even 5% can be taken as significant at atrial level [1], though it is not often the case. For a simplified assessment, SVC to PA step up can give an idea of the shunt as complete mixing of atrial blood occurs in the right ventricle and PA s...
Source: Cardiophile MD - Category: Cardiology Authors: Tags: General Cardiology Source Type: blogs