Tachycardia (Narrow Complex)

Question 1

What are the 3 care objectives associated with Narrow Complex Tachycardia?

Answer 1

1. Terminate life-threatening arrhythmias and transport to definitive care
2. Rapid transport to facilitate treatment of an arrhythmia not able to be done pre-hospitally
3. Early termination of SVT following ECG capture

Question 2

How should adenosine be administered?

Answer 2

Rapidly, through a large vein proximal to the heart (cub fossa) followed by a normal saline bolus flush.

Question 3

How is AF/SVT deteriorating to pre-arrest treated?

Answer 3

Synchronised cardioversion, 200J.

Question 4

What are the signs/symptoms of a rapidly deteriorating pt in this guideline?

Answer 4

1. Inadequate perfusion/shock (hypotension, pallor, diaphoresis)
2. Acutely ALOC or LOC
3. Ischaemic chest pain
4. APO

Question 5

At what rate would you expect to see signs and symptoms of unstable, rapid deterioration?

Answer 5

Rates of 150bpm or higher, unless there is impaired cardiac function.

Question 6

Outline the steps of a standard Valsalva.

Answer 6

1. Pt supine
2. Record 12 Lead ECG
3. Take a normal breath in
4. Forced expiration for 15s into a 10mL syringe, hard enough to move the plunger

Question 7

Outline the steps of a Modified Valsalva.

Answer 7

1. Position semi-recumbent
2. Record 12 Lead ECG
3. Take a normal breath in
4. Forced expiration for 15s into a 10mL syringe, hard enough to move the plunger
5. Immediately lay the patient flat and raise their legs to a 45 degree angle for 15s.
6. Return the pt to the semi recumbent position.

Question 8

What is the target pressure for a Valsalva and how is this achieved?

Answer 8

40mmHg, blowing for 15s into a 10mL syringe, hard enough to move the plunger.

Question 9

How many times can a Valsalva be repeated and at what intervals?

Answer 9

Max. 3 attempts at 2 minute intervals.

Question 10

What SBP contraindicates a Valsalva?

Answer 10

SBP <90mmHg.

Question 11

What conditions are indicated for Valsalva?

Answer 11

Stable SVT - AVRT or AVNRT

Question 12

What rhythms must be excluded before attempting a Valsalva?

Answer 12

AF and atrial flutter.

Question 13

What is the physiological action of a Valsalva?

Answer 13

Mechanism of Action
1. Forced expiration increases intrathoracic pressure, decreasing venous return and cardiac output.

2. This is detected by carotid baroreceptors, which respond to the decreased venous return by increasing sympathetic drive – resulting in increased heart rate and contractility, and vascular constriction to increase venous return and support blood pressure.
3. On cessation of forced expiration, the sudden increase in venous return is detected by carotid baroreceptors and stimulates an increase in vagal tone.
4. Vagal innervation stimulates muscarinic receptors within the AV node to slow electrical conductivity, potentially to the point that the re-entrant circuit is interrupted and normal sinus rhythm is resumed.

Question 14

When would MICA be required for this condition?

Answer 14

1. SBP contraindicates Valsalva, or no reversion with Valsalva - Adenosine required.
2. Unstable and rapidly deteriorating - Synchronised cardioversion required.

Question 15

How is non-AVNRT/AVRT managed and what rhythms might this encompass?

Answer 15

AF, Atrial Flutter, M.A.T

Manage with pain relief.