Pregnancy: SVT Rx

There is an increased propensity for tachydysrhythmias (usually SUPRAventricular) during pregnancy – at least 50% of parturients will experience atrial and ventricular ectopy. Sinus tachycardia and SVT are common as well. Why? Hyperdynamic circulation, and increase awareness among some women.

The causes of increased arrhythmias are multiple, including a change in Ca ion channel conduction, an increase in cardiac size (atrial stretch, increased EDV), changes in autonomic tone (increased SNS stimulation and adrenergic sensitivity), and hormonal changes. Dysrhythmias are more common if patient has underlying structural cardiac disease (ie VSD, ASD) or unabnormal conduction pathway (WPW, Long QT syndrome).

Most antiarrhytmics are category C (studies in pregnant women are lacking), with a few exceptions – lidocaine and sotalol (category B, no evidence of risk in pregnant women), and amiodarone (category D, positive evidence of risk).

For SVT, consider non-pharmacologic means first (vagal maneuvers). Attempt adenosine as first-line pharmacotherapy, followed by verapamil, digoxin, or β-blockers (not as effective as CCB). If an accessory pathway is present, try procainamide or quinidine. RF ablation and/or electrical cardioversion are reserved for refractory cases.

Pregnancy: Supraventricular Tachycardia

• Incidence: > 50% of parturients will have some type of arrhythmia, ectopy being the most common
• Etiology: atrial stretch, hyperadrenergic (stimulation and receptors) state
• Treatment of SVT: vagal maneuvers; adenosine; verapamil, digoxin, or β-blockers (category C)

Previous Content

Which Supraventricular dysrhythmias? PAD>nonconducted P waves>ectopic atrial tachycardia> WAP> sinus pause> retrograde P waves -overall though, sinus tach/brady are more common than SVdysrhythmias

Dx -hx, PE – ekg, holter – cxr( not routine, but can be done w/ fetal shield) -echo -cardiac cath(caveat: increase in rads xposure to fetus)

Are there Hd changes? Is the dysrhythmia sustained?

– if the answer is Y to either above, then TREAT, otherwise reassure

Dysrhymias

1. PSVT -HR 140 to 220 – increased p waves RX: slow AV conduction

2. drugs: adenosine, CCB(verapamil>diltiazem), Bblockers(not as effective as ccb)

3. cardioversion w/ 50J, usually done for HD instability

4. anticholinergic rx : edrophonium

5. rapid atrial pacing: in refractory cases

1. vagal maneuvers (can terminate 20 to 25% of reentry svt): carotid massage,sinus massage, valsalva, gagging

2. PAD

a. Skipped beats

b. VERY common

c. Rx: reassure pt, avoid caffeine

3. A flutter

a. Types i. Type One: AR 300, VR 150 ii. Type Two: AR >350

b. Rx : rapid atrial pacing(type one -Drugs(type two) -cardioversion

4. A fib – AR 350 to 600 – VR 100 to 200 – Irregular, no p waves – Rx: slow VR w/ drugs and prevent recurrence w/ rx