Syncope

Syncope comprises generalized weakness of muscles, loss of postural tone, ability to stand upright and a loss of consciousness. It is one type of disease of cardio vascular system. Various types of syncope are vasovagal syncope, Cardiac syncope, and orthostatic syncope. In vasovagal syncope mechanisms includes reflex slowing of heart mediated through vagus, and marked fall in arterial pressure and peripheral vascular resistance and it causes emotional stress, warm overcrowded room, sudden pain, mild blood loss, anemia fever and fasting. Clinical features include a prodromal phase characterized by nausea, sweating, yawning, tachypnoea, weakness and confusion. Cardiac syncope is due to a sudden reduction in cardiac output. This can occur when the heart is beating too fast or too slow when it is not beating at all. Common causes of cardiac syncope are complete heart block, primary pulmonary hypertension, tetralogy of fallot, aortic stenosis, sick sinus syndrome, paroxysmal tachycardias. Orthostatic syncope occurs when the person suddenly gets up from a lying down position or stands still for a long time. Basic mechanism is postural hypotension resulting from loss of vasoconstrictor reflexes in the lower limb vessels. Common causes are hemorrhage, drugs , physiological, idiopathic orthostatic hypotension and diabetic neurotheraphy and tabes dorsalis.