SYNCOPE

 Syncope is a sudden loss of consciousness resulting from inadequate blood flow to the brain. When an individual experiences dizziness, it is referred to as presyncope, whereas blackout refers to a sudden loss of consciousness. The most common types of syncope include vasovagal syncope, postural syncope, medication-induced syncope, and cardiac syncope.

VESOVAGAL SYNCOPE (COMMON FAINT)

•Vasovagal syncope is caused by excessive vagal activation and decreased venous return. This is often triggered by prolonged standing, large meals, stressful or painful stimuli such as fear, pain, unpleasant sights, prostration, hot environments.

•It occurs due to a reduction in venous return to the heart, while the sympathetic nervous system is simultaneously inhibited.

Stimulation resulting in vigorous compression of the fairly under-filled ventricles, leading to kickback through the stimulation of ventricular mechano-receptors, can activate the parasympathetic (vagal) system and cause sympathetic pullout, resulting in bradycardia, vasodilation, or both. Variants of vasovagal blackout, such as cough blackout and micturition blackout, exist. Symptoms of vasovagal blackout include pallor, slow palpitation, low blood pressure, and dilated pupils. 

Diagnosis 

The head-up tilt test is a diagnostic test for vasovagal blackout. During this test, the patient is asked to lie on a table that is tilted at an angle of 70° for over 45 minutes while their ECG and blood pressure are monitored. A positive test is indicated by significant bradycardia or potentially hypotension. 

Treatment 

•Treatment for vasovagal blackout includes the use of beta-blockers to inhibit the initial sympathetic activation.

• Binary chamber pacing may be necessary if bradycardia is predominant.

POSTURAL SYNCOPE 

Postural blackout is a medical condition that arises due to the failure of the normal compensatory mechanism of baroreceptors. These receptors are responsible for regulating heart rate and supplemental resistance in response to changes in posture. When the supplemental resistance drops, it causes vasodilatation and leads to hypotension, which is commonly known as postural hypotension. A decline in systolic pressure of more than 10 mm Hg immediately upon rising from a supine to standing position is indicative of postural hypotension. This sudden drop in blood pressure reduces cerebral blood inflow, resulting in blackout. Postural blackout is a frequent cause of outpatient department visits by patients taking ACE inhibitors and diuretics. 

Predisposing factors 

Several factors can contribute to the development of postural blackout, including 

•old age

•Parkinson's disease

•diabetes, and other cases with autonomic neuropathy. 

•Blood loss or hypovolemia, as well as the use of certain medications such as vasodilators, antidepressants, beta-blockers, and diuretics, can also increase the risk of postural blackout.

Treatment 

•The recommended course of action is to withdraw or reduce the dose of the responsible drug.

 •Additionally, patients should be advised to wear elastic stockings and to get up slowly from the bed.

• In some cases, NSAIDs and fludrocortisone may be required.

CARDIOGENIC SYNCOPE

 is a condition that results from profound hypotension due to a combination of a reduction in cardiac output and a drop in peripheral vascular arrhythmia. 

Cause

The causes of this condition include.

 tachyarrhythmias

•ventricular tachycardia

•supraventricular tachycardia.

 bradyarrhythmias

•sick sinus syndrome

•heart block.

 Mechanical obstruction

•myocardial infarction

• aortic or pulmonary stenosis

• pulmonary hypertension or embolism

• atrial myxoma or thrombus

•hypertrophic obstructive cardiomyopathy

• Fallot's tetralogy

 • stuck-up prosthetic valve.