Cardiology - SVT

Question 1

Group of tachyarrhythmias originating in the atria or the AV node (above the ventricles)

Answer 1

Superventricular tachycardia (SVT)

Question 2

Types of SVT

Answer 2

• atrioventricular NODAL REENTRANT tachycardia (AVNRT)
• atrioventricular RECIPROCATING tachycardia (AVRT)
• focal atrial tachycardia
• multifocal atrial tachycardia
• junctional tachycardia

Question 3

A mechanism that causes an impulse in the heart (that would normally die out) to return via conduction circuit to re-excite the tissue, leading to an extra beat or an ongoing tachyarrhythmia.

Answer 3

Re-entry

Question 4

Type of SVT caused by abnormal conduction circuits that form an unending loop of conduction referred to as “reentry”

Answer 4

AVNRT and AVRT

Question 5

Reentry circuit between parallel pathways within the AV node

Answer 5

AVNRT

Question 6

What is the pathway for AVNRT?

Answer 6

• The AV node has 2 electrical pathways (one fast and one slow)
• The electrical impulse circles around the AV node in both pathways
• A continuous circuit conducts impulses to the ventricles causing tachycardia

Question 7

EKG findings on AVNRT

Answer 7

• narrow QRS complex
• “buried” P wave - typically not visible

Question 8

Reentry circuit between the AV nose and an accessory pathway

Answer 8

AVRT

Question 9

What is the pathway for orthodromic AVRT?

Answer 9

• antegrade conduction from atrium to ventricle through AV node
• retrograde conduction from the ventricle to the atrium through an accessory pathway

Question 10

What is the pathway for antidromic AVRT?

Answer 10

• antegrade conduction from atrium to ventricle through the accessory pathway
• retrograde conduction from the ventricle to the atrium through the AV node

Question 11

EKG findings of orthodromic AVRT

Answer 11

• narrow QRS complex
• p wave typically follows the QRS complex

Question 12

Most common congenital accessory pathway syndrome

Answer 12

Wolff-Parkinson-White (WPW)

Question 13

EKG findings of WPW

Answer 13

• short PR interval
• EKG delta wave (slurred upstroke at the start of the QRS complex secondary to pre-excitation)
• widened QRS

Question 14

Clinical features of SVT

Answer 14

• palpitations
• chest pain or discomfort
• dyspnea
• dizziness
• syncope or pre-syncope
• diaphoresis

Question 15

Signs of unstable SVT

Answer 15

• acute pulmonary edema
• hypotension
• severe chest pain
• altered mental status

Question 16

EKG findings of SVT

Answer 16

• NARROW QRS complex ( <120 ms)

Question 17

First therapeutic interventions in paroxysmal SVT

Answer 17

Vasovagal maneuvers (Valsalva maneuver, Carotid sinus massage, Diving reflex)

Question 18

Treatment for unstable SVT

Answer 18

electrical cardioversion

Question 19

Treatment for stable regular SVT

Answer 19

• Vagal maneuvers
• adenosine
• non-DHP CCB or Beta blockers