Effects of a lack of aortic "Windkessel" properties on the left ventricle.

After the long bypass grafting between ascending and abdominal aorta with exclusion of the aortic arch using conventional synthetic vascular graft, a considerably remarkable hemodynamic change and progressive hypertrophy of the left ventricle occurred until stabilized. In the clinical cases and animal experiments, systolic hypertension, diastolic pressure decrease and consequent pulse pressure widening were observed. Furthermore, the phase difference between flow and pressure waves approximated to zero. Elevation of the afterload due to systolic hypertension and widening of pulse pressure may result in energy loss in vascular pulsation, not maintaining forward flow but increasing the left ventricular external work. Furthermore, as the peak flow approximates the peak pressure and its point situated relatively early in systole, external work and wall stress of the left ventricle are markedly elevated. All those factors mentioned above lead concentric hypertrophy of the left ventricle to normalize the wall stress. Fall in the diastolic pressure at the aortic root may decrease coronary flow to lead ischemia of the hypertrophied left ventricle. This can occasionally lead to fatal heart failure after a long postoperative period. It may be concluded that these new findings are produced by a loss of compliance (Windkessel properties) in aortic root which occurred as consequence of using conventional synthetic vascular graft with exclusion of aortic arch.