tailieunhanh - MEDICINE HURST VENTRICULAR ELECTROCARDIOGRAPHY - Part 2

Giả sử tim tạo ra chỉ có ba lực lượng điện. Có giả thiết này, các lực lượng điện được hình dung như là các vectơ (mũi tên), như thể hiện trong hình này. Lưu ý rằng số lượng mũi tên là một trong những hướng dẫn bên phải, inferiorly và phía trước. | 29 Figure Suppose the heart generates only three electrical forces. Having made this supposition let the electrical forces be visualized as vectors arrows as shown in this figure. Note that arrow number one is directed to the right inferiorly and anteriorly. Arrow number two is directed to the left inferiorly and parallel with the frontal plane. Arrow number three is directed to the left and posteriorly. There are five major factors that determine the characteristics of the vectors arrows that represent the electrical forces of the heart. They are a the location of the heart in the thorax b the transmission of the electrical forces of the heart to the body surface c the exact location and anatomic features of the atria and ventricles d the unique anatomy of the conduction system and e the sensitivity of the measuring device the electrocardiograph machine . The Location of the Heart in the Thorax Austin Flint of auscultation fame published a beautiful drawing of the heart Fig. in 1859. 1 Note that the heart is nearer to the anterior portion of the chest wall than it is to the lateral or posterior portions. 30 Figure Austin Flint 1859 published this diagram and legend. A. The relations of the heart to the thoracic parietes. The letters a b c etc. indicate the ribs. The numbers 1 2 3 etc. mark the intercostal spaces. The vertical line denotes the median line. The right triangle extending over a portion of the surface of the heart represents the superficial cardiac region as delineated on the chest with sufficient accuracy for practical purposes. The cross on the fourth rib shows the situation of the nipple. The relations of the ventricles auricles apex of the heart aorta and pulmonary artery to the ribs and intercostal spaces the median line and the nipple are accurately indicated. B. The relations of the heart to the pulmonary organs liver and stomach. The quadrangular space in which the heart is uncovered by lung is the superficial cardiac region .