Cardiac surgery

Cardiac function relies on its normal electric initiation and conduction, myocardial contractility, and all four valves ensuring the blood flowing in normal direction. To maintain this function, adequate coronary blood/oxygen supply to the heart is critical. In basic cardiac electric system, the rhythmic cardiac contraction originates spontaneously in the sinoatrial node (SA) located in the wall of RA adjacent to superior jugular vein (SVC) opening; electric impulse is conducted to the atrioventricular node (AV) located at the lower part of atrial septum immediately above the attachment of septal cusp of tricuspid valve; then the electric signal travels to the bundle of His (or AV bundle) and continues to the right bundle branch and left bundle branch and finally extends into the small Purkinje fibers. In cardiac cycle, after RA and LA receive systemic venous return and pulmonary blood return, respectively, atrial contractions move blood into RV and LV, respectively; this is the diastole. Then LV contracts to propel blood into the aorta and then systemic circulation, and RV contracts to force blood into pulmonary artery; thus, deoxygenated blood gets oxygenation in the lungs. This phase is called systole.