Question

Which of the following may be employed to treat NCS? Select all that apply.

a)Mineralocorticoids

b)Disopryramide

c)Beta-adrenergic blockers

d)ACE inhibitors

e)Alpha agonists

f)Alpha antagonists

g)Compression stocking

h)counter-maneuvers

Answer 1

Answer :

a] Mineralocorticoids

c] β adrenergic blockers

e] Alpha agonists

g] Compression stocking

h] Counter-maneuvers

[ Note :

Disopyramide is an anti-arrhythmic drug, which can cause Hypotension ; hence should not be used in NCS.

Alpha antagonists (eg: Prazosin) decrease vascular resistance and decrease blood pressure.]

EXPLANATION

NEUROCARDIOGENIC SYNCOPE

The sequence of events leading to syncope is thought to be triggered by venous pooling.

This leads to decreased activation of baroreceptors in the aortic arch and carotid sinus, causing increased sympathetic tone.

This results in increased ventricular contractility, which in turn activates receptors attuned to wall tension in the left ventricle and thus paradoxically increases vagal output.

Increased vagal tone leads to profound vasodilation, which causes syncope.

TREATMENT OF NCS

A] CONSERVATIVE MANAGEMENT

1] Increase fluid and salt intake

2] Physical counterpressure maneuvers (PCMs) : are movements like leg-crossing and hand-gripping motions that increase systemic vascular resistance and blood pressure, thereby counteracting the vaso-depressor effect that leads to syncope.They help in preventing loss of consciousness in patients who can appreciate the preceding presyncopal symptoms.  

3] Compressive stockings : can help to decrease venous pooling , and therefore may be useful in preventing NCS.

B] PHARMACOLOGICAL THERAPY

1] Midodrine

Midodrine, a drug whose active metabolite is an alpha-1 adrenergic agonist, may help to prevent NCS through its vasoconstrictive effect. This vasoconstriction can counteract the vasodilation seen in NCS.

2] β-Blockers: β-Blockers (eg : metoprolol) were one of the first medications to be tested as medical therapy for NCS. Since β-adrenoreceptors partially mediate ventricular baroreflex, which subsequently leads to vasodilation and venous pooling in patients with syncope, β-blockers are thought to be useful in attenuating this response.

3] Selective serotonin reuptake inhibitors.: Changes in serotonin levels can affect blood pressure and heart rate via the central serotonergic pathway, which can contribute to NCS in some patients. SSRIs may work by stabilizing serotonin levels in the central nervous system.  

4] Fludrocortisone. Fludrocortisone , due to their mineralocorticoid activity ,can be used as an adjunct to increasing fluid and salt intake in the prevention of syncope.

As a mineralocorticoid receptor agonist, it causes reuptake of sodium and water in the kidneys, thus increasing circulating plasma volume.

C] INTERVENTIONAL PROCEDURES

1] Cardiac pacemaker implantation

The procedure is reserved for patients with severely reduced quality of life due to frequent syncope and who have failed to respond to conservative and medical approaches.

2] Cardiac ganglion ablation

The vagal innervation to the heart is primarily supplied through ganglia located in the atrial wall and specific epicardial fat pads.

These cardiac ganglia contain several neuronal cell bodies that innervate the SA node and AV node , thereby controlling the parasympathetic innervation to the heart.

The ablation of these ganglia will attenuate the bradycardic response and thus help to prevent NCS in patients with a primarily cardioinhibitory component.