Abstract
The communication from right to left through the interventricular septum of the heart became identified by the anatomical study for 4 years. One thousand nine hundred years ago, Galen stated that blood seeps through the perforations in the interventricular septum of the heart. However, William Harvey, working 400 years ago, failed to find any. The interventricular vessel is a slit between the fibers of the muscle feasible to be patent by relaxing and widening of the helical heart at the right atrial filling phase at the end of the diastole. The case exhibited the flow of venous blood passing from right to left through the interventricular vessel at the right atrial filling phase concordant to the fourth heart sound. The earliest left ventricular activation closed the interventricular sphincter surrounding the interventricular vessel in the middle of the left muscular part of the interventricular septum. The fourth heart sound is common at the atrial filling phase in hypertrophy of systemic hypertension and in ischemic heart disease. It is necessary to explore vigorously the unknown etiology of the fourth heart sound (S4).