Thursday, January 5, 2012
The pulmonary manifestations of heart disease are due to pulmonary edema, e.g. dyspnoea, cough, sputum and reputations or to pulmonary hypertension, e.g. haemoptysis. Pulmonary infarction frequently accompanies heart failure and is described. In addition, certain diseases of the lung, notably emphysema, may themselves be responsible for heart failure. The Electrocardiograph is a sensitive meter which amplifies and records the difference in electrical potential between any two points on the surface of the body. It is capable of detecting the electrical activity (depolarization and depolarization) which accompanies muscle fiber contraction, and the electrocardiogram is the graphic representation of these electrical changes. It does not represent the actual muscular contraction. The simplest type of electrocardiograph consists of a galvanometer and two metal plates (electrodes) which are attached to two points on the body surface. The resulting tracing is termed a lead, and because two electrodes are used it is termed a bipolar lead.