Their high calcium content is usually the star of the show, but donât let it blind you to everything else in the can. 1  Sardines also deliver: 2  Selenium (69%) 3  Phosphorus (45%) 4  Iron (15%) 5  Magnesium (9%) 6  Copper (9%) 7  Zinc (8%)
Premature ventricular contractions (PVCs, PVC) are premature heartbeats originating from the ventricles of the heart. Premature ventricular contractions are premature because they occur before the regular heartbeat. Normal function of the heart. The heart has four chambers.
Premature ventricular contractions (PVCs) are premature heartbeats originating from the ventricles of the heart. Premature ventricular contractions are premature because they occur before the regular heartbeat.Normal function of the heart. The heart has four chambers.The upper two chambers are the atria, and the lower two chambers are the ventricles.he SA node is the heart's electrical pacemaker. It is a small patch of cells located in the wall of the right atrium; the frequency with which the SA node discharges electricity determines the rate at which the heart normally beats. The SA node keeps the heart beating in a regular manner.