Basic EKG Interpretation - Georgia College Georgias Public 基本的心电图解释，乔治亚大学的乔治亚州的公共.ppt

Basic EKG Interpretation History Mid 1880’s - Ludwig Waller discovered that the heart’s rhythm could be monitored from a person’s skin 1901 - Dr. William Einthoven invented the EKG machine EKG - Electrocardiogram - Electrical activity of the heart (contraction of the myocardium) Electrical Conduction Heart muscle cells - “myocytes” “Depolarization” moves as a wave through the myocardium “Depolarization” stimulates the heart’s myocytes, they become + and contract Cell-to-cell depolarization through the myocardium is carried with Na+ ions EKG Myocardial contraction is caused by depolarization. The recovery phase that follows depolarization is known as repolarization. The SA Node (“Sinus Node) is the heart’s dominant pacemaker. - Sinus Rhythm Each depolarization wave emitted through the SA Node spreads through the atria producing a P Wave. P Wave = Atrial Depolarization AV Node - Conducting pathway b/t the atria and the ventricles When a wave of atrial depolarization enters the AV Node, depolarization slows, producing a brief pause, thus allowing blood to enter the ventricles. Ca++ ions Ventricular Conduction Depolarization shoots rapidly through the HIS Bundle, and the Left Right Bundle Branches The HIS Bundle and both Bundle Branches are made up of rapidly conducting Purkinje fibers. Depolarization of the entire ventricular myocardium produces a QRS complex. QRS represents ventricular contraction. Ventricular Conduction The Q Wave, when present, always occurs at the beginning of the QRS complex and is the first downward deflection. The next upward deflection represents the R Wave. The next downward wave is the S Wave. The horizontal segment of baseline that follows the QRS is known as the ST Segment. Continued. If the ST Segment is elevated or depressed beyond baseline level, this is usually a sign of problems. The ST Segment represents the initial phase of Ventricular Repolarization. The T Wave represents the final, “rapid” phase of ventricular repolarization.