This chapter discusses about the Classical or traditional hemodynamic features of constrictive physiology. There are five features of constrictive physiology are equalization of diastolic pressures, dip and plateau or called as square root feature, right ventricular end-diastolic pressure is more than one third of the systolic pressure, pulmonary artery systolic pressure is less than 55 mm of hg and lack of respiratory variation of mean RA pressure. The systolic area index is defined as the ratio of the RV area to the LV area in inspiration versus expiration. Cardiac hemodynamic data is very useful in the diagnosis of constriction and in the differentiation from restrictive physiology.