Peri-op Cardiac Arrhythmias, cause, recognition and treatment.

Presented by R1 林至芃 2000.5.04

Case presentation

77y/o female, DM poor control, HTN….. Necrotizing pneumonia with respiratory failure s/p

intubation and ventilator support hemopneumothorax, poor chest tube function

came to OR for VATS. PSVT with hemodynamic compromise

successfully stopped by esmolol+phenylnephrine Af with RVR after PSVT stopped.

Peri-op Cardiac Arrhythmias

High incidence (15%-85%) healthy individuals supraventricular, ventricular, short run

VT from infant to eighties. Less than 1% are life-threatening.

Peri-op Cardiac Arrhythmias

Physiology:1.Action potential. 2.Pace maker cells. 3.Conduction system.

Electrophysiology of arrhythmia. Anti-arrhythmic drugs. Management of perioperative arrhythmia.

Action potential of myocardium

phase 0,1,2 => absolute refractory

phase late3, 4=>relative refractory

Pacemaker cells and myocardium

Classification of arrhythmia

Bradyarrhythmia: sinus bradycardiaAV block- 10degree, 20 degree (Mobitz type I , Mobitz type II) 30 (complete)

Premature complexes:PACs, PJCs, PVCs.

Classification of arrhythmia Tachycardia:

A. Narrow complex tachycardia 1.Sinus tachycardia 2.Atrial tachycardia 3.AV junctional tachycardia 4.AVNRT 5.AVRT 6. W-P-W syndrome 7.Atrial fibrillation 8.Atrial flutterB. Wide complex tachycardia 1.SVT with aberration 2.In WPW 3.AIVR 4.VT 5.VF 6.Torsades de pointes.

Sinus bradycardia

PR<60/min increased vagal tone, antiarrhythmic drugs

effect, ischemia, primary sinus node disease 0.2-2 mg atropine, pacing.

AV block

10 AV block: PR>200ms, conduction delay

in AV node 20 -Mobitz type I, delay within AV

node, inferior or posterior ischemia 20 -Mobitz type II, His-Purkinje system,

anterior distribution. 30 -complete heart block, congenital,

infarction or ischemia, drug, idiopathic degeneration.

Premature complexes-PVCs most common arrhythmia occur with and without heart disease adult males, 60 percent. up to 80 percent previous MI, if frequent

(>10/h) or/and complex (couplets)=>increased mortality.

wide (usually >0.14 s), bizarre QRS complexes no preceding P waves

Premature complexes-PVCs

No cardiac dz: isolated asymptomatic VPCs, regardless of configuration and frequency, need no treatment.

Beta- blockers (daytime or under stressful situations,MVP, thyrotoxicosis.

In AMI, first 24 h Temporary prophylactic antiarrhythmic therapy with lidocaine or procainamide.

Narrow QRS tachycardia

Sinus tachycardia: Tx targeted at underlying Atrial tachycardia:

pulmonary dz => MAT, theophyllinedigitalis toxicity=> PAT with 20 AV-block => lidocaine, beta-blocker

AVNRT: most common PSVT orthodromic AV reciprocating tachycardia

Narrow QRS tachycardia

WPW syndrome: preexcitation, delta wave. Af with WPW=>VF

Af: most common sustained tachycardia (10% of older than 75y/o)acute Af with RVR, unstable=> DC shockchronic AF, for RVR control=> Ca blocker, beta blocker are rapid and effective digoxin for LV dysfunction.

A flutter: sawtooth pattern baseline, esp II, III, aVF

Wide QRS tachycardia

SVT with aberration AIVR: terminal purkinje, myocardium.

Acute MI, inflammatory process 60-130/min, atropine, overdrive pace

VT: most common life-threatening form. CAD, CM, other inflammatory process D/D: SVT with aberration. Tx: synchronized DC shock procainamide, lidocaine, amiodarone

Wide QRS tachycardia

VF: immediate unsynchonized DC shock Torsades de Pointes: polymorphic VT.

Tx: magnesium sulfate.

Electrolyte Imbalance and pH

Low Potassium (acute/severe) => ventricular arrhythmia

Sodium => not significant Magnesium => low ->interfere Na-K pump

produce primarily SVT =>2 gm despite actual Mg level to reduce post-CPB SVT

arrhythmias are not major seguela of acute pH change.

Anesthesia

Most anesthetics are calcium antagonistic => anti-arrhythmic

halothane sensitize heart to circulating or exogenous catecholamines.

Potentiate myocardial suppression effect of antiarrhythmic agent.

Classic anti-arrhythmic drugs I: membrane stabilizer, block fast Na channels

Ia: quinidine, procanamide => not available!!Ib:lidocaine=>useful for all ventricular arrhythmia SVT with aberration=> harmless! 2% lidocaine, 100mg/amp 20mg/ml a.post-defib VT/VF 1.5mg/kg b.Stable VT, undetermined wide QRS tachycardia 1-1.5 mg/kg 5-10 min 1/2 dose repeat x 2-3 c.post DC or post-MI 的警示性 VPC (>6/min,

R-on-T, couplets or short-run, polymorphic) 0.5mg/kg (may repeat x3)

Classic anti-arrhythmic drugs II: beta-blocker

effective in all tachycardic arrhythmia even in LV dysfunction when RVR superimposed

III: prolong repolorization, effective in all arrhythmia, including bupivacaine induced arrhythmia amiodarone (150mg/3ml/amp) for refractory, repetitive VT/VF Loading 150mg over 10 min than 1mg/min Cx: hypotension, QT-prolong!

Classic anti-arrhythmic drugs IV: calcium channel blocker

effective in SVT, Af, AF. Contraindicated in narrow QRS Af with known WPW! Ineffective at ventricular arrhythmia!! Verapamil (Isoptin 5mg/ml/amp) a. systolic >90 mmHg b. AF, Af, MAT: effectively decrease ventricular resoponse!(esp diltiazem, less myocardium suppression ) c. 2.5-5mg slowly push for 2 min, 15-30 min repeat, Max 30mg, may pre-treat CaCl2

Other anti-arrhythmic drugs

Adenosine(6mg/2ml/vial)for PSVT (I) 6mg -> 12mg rapid push!!transient bradycardia, even asystole (max15 sec)

Digoxin(0.25mg/1ml/amp)AF, Af, PSVT : ventricular rate control0.25-0.5 mg slow push for loadingonset 5-30 min, peaking 1.5-3 hrbe careful: HypoK

Other anti-arrhythmic drugs

MgSO4: (2gm/20ml/amp)a. Torsade de Pointes or refractory VF/VTb. Post-CPB SVTc. post-MI ventricular arrhythmia d. 1-2 g solwly pushe. hyperMg, decrease DTR, hypotension, resp muscle paralysis, f. antidote:CaCl2

What we forget?!

Defibrillator TCP Bradycardia Call for help!?

Thanks for your attention!