Means for load variation during echocardiographic assessment of the Frank-Starling relationship

Because minimally invasive methods of preload variation are not validated f or load-insensitive indexes of cardiac performance, intravenous nitroglycer in (NTG), phenylephrine, and saline solution (VOL) boluses were used in blo cked and intact autonomic states to alter load and were compared with vena caval occlusion in the assessment of preload recruitable stroke work relati onships between stroke work and left ventricular end-diastolic volume in do gs. In both autonomic states NTG and VOL produced comparable linear relatio nships. NTG and saline solution were combined with noninvasive measurements of left ventricular pressure and volume to construct echocardiographic rel ationships between stroke work and left ventricular end-diastolic cross-sec tional area; NTG produced linear relationships similar to vena caval occlus ion. Therefore NTG and VOL reliably alter load in constructing preload recr uitable stroke work relationships, and NTG may be used with noninvasive mea surements to provide load-insensitive estimates of cardiac function in a mi nimally invasive manner.