arrhythmias after cardiac surgery

8/6/2019 Arrhythmias After Cardiac Surgery

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POST CARDIAC SURGERY ARRHYTHMIAS

30/4/11

Post cardiac surgery arrhythmias

Potential causes and precipitating factors

Myocardial ischemia or infarctionHemodynamic instability

Electrolyte abnormalitiesa) Hypokalemia, b) Hypomagnesemia

Metabolic disturbancesa) Acidosis, b) Alkalosis, c) Hypoxemia

Drugsa) Sympathomimetics, b) Antiarrhythmics, c) Anesthetic

Reperfusion effectTissue trauma or inflammation, indwelling cathetersIncrease in catecholamines

Common arrhythmias after cardiac surgery

1. Sinus tachycardia

2. Ventricular premature complexes

3. Ventricular tachycardia

4. Atrial fibrillation, atrial flutter

5. AV & IV conduction block

Sinus tachycardia

Causes

Anxiety Low cardiac output

Anemia

Beta blocker withdrawal

Managed by treating the underlying cause

Ventricular premature complexes

VPC ² couplet

VPC ² complex form

Ventricular arrhythmias

Management of PVC·s and NSVT

y Simple PVCs usually do not require Rx

y If frequent and symptomatic can besuppressed with beta blockers or AA

y No role for prophylactic lidocaine

MAN AGEMENT OF POST CABG VT/VF

Post CABGSust. Vent. Tachyarryth.

Ventricular Fibrillation

Defib / IV Amiodarone

Identify/Tr eat ppt factors

No further AA therapy

Recurr enceUse other IV drugs

EPS guidedAA therapy

UnsuccessfulConsider ICD therapy

SuccessfulContinue the drugs

Ventricular tachycar dia

Unstable

Use V-Fib Protocol

Stable

IV Amiodarone

Tr eat Ppt factors

Recurr ence

Use V Fib recurr. protocol

No r ecurr ence

No further therapy

No Recurrence

Atrial fibrillation

Atrial flutter

Postoperative AF may occur in...

40% of patients undergoingCABG

35% to 40% after valvular surgery

60% after combinedCABG and valve surgery

11% to 24% after cardiac transplantation

Clinical implications

Increased incidence of postoperativecomplications : hypotension

MI / CHF

CVA/ decline in Mini-Mental State Examination score

Respiratory failure

Renal dysfunction

Infections longer length of hospital stay

lower in-hospital and long term survival

Pre-operative risk factors

Advanced age

Male gender

Hypertension

Previous AF History of cardiac surgery

RCA disease

Peripheral vascular disease

Valvular heart disease

Left atrial enlargement

Electrocardiographic

features-P wave durationon SAECG

Renal failure

Moderate or severe aorticatherosclerosis

Withdrawal of beta-blockeror ACEI/ use of digoxin

Obesity and metabolicsyndrome

Intraoperative risk factors

Aortic cross-clamp time

Bicaval cannulation

Pulmonary vein venting Lack of use of topical ice slush

Type of surgery

Need of perioperative IABP

CPB time

CPB inclusive of cardioplegic arrest

Systemic hypothermia

Post-operative risk factors

Respiratory compromise

Red cell transfusion

Day of onset of atrial fibrillation after

1 2 3 4 5

POST-OPERATIVE DAY

Klein et al.Am Ht Jn, 1995;129:895 - 901

L ength of stay in hospital after postopatrialarrhythmias

D a y s

ICU WARD

Without atrialarrythmia

With atrial arrythmia

Cr eswell et al, Ann. of Thoac. Surg, 1993;56:539 -

Prevention of post-operative AF

Beta blockers should be administered peri-operatively, 1 to 2 weeks pre op, in patientswithout contraindications until the day of

surgery (Class I A) Preoperative administration of oral

amiodarone,6days prior, for patients who havecontraindications to therapy with beta-blockers

and high risk of AF (PAPABEAR) (Class IIa A) Low -dose sotalol should be considered in

patients who are not candidates for traditionalbeta-blocker (Class IIb A)

Bi-atrial overdrive pacing has been shown to

be effective in preventing postoperative

AF (IIb A) Corticosteroids may decrease the incidence

of postoperative AF by reducing the

inflammatory response after surgery (IIb B)

All patients without contraindications for

statin therapy should receive it ( 40mg/d, 7

days prior) beforeCABG surgery(ARMYDA 3)

prophylactic magnesium therapy is not

routinely recommended

no indication for using digitalis / CCB for theprevention of postoperative AF.

The AmericanCollege of Chest Physicians

guidelines recommend the following possible

intraoperative preventive strategies :

mild hypothermia (for example, 34C)

the use of posterior pericardiotomy

heparin-coatedCPB circuits

Off-pumpCABG Vs conventional CABG with

Contradictory evidence concerning the advantageof OPCAB in reducing the rate of postoperativeAF

Management

Spontaneous conversion of AF may occur

within 2 hours in 15% to 30% of patients and

within 24 hours in 25% to 80% of patients.

Cardioversion

Direct current cardioversion

Biphasic external defibrillators: lower energy

requirements and greater efficacy

Anteroposterior electrode placement is moreeffective

Synchronized with the QRS complex

High energy is required for AFcardioversion - atleast 120 J , biphasic

Conduction Disturbances

y Transient conduction disturbances can occur in4% to 58% of patients afterCABG

y Incidence of isolated AV block is low afterCABGbut may be higher after associated valve surgery

Conduction disturbances

First Degree AV block

y Most commonly due to:

y fibrosis of AV node

y toxicity of medications

such as beta blockers orcalcium channel blockers

y edema of AV node region

after mitral and aorticvalve replacement

y No specific therapy isusually needed

Second-Degree AV block

y MobitzType I and Type II blocksare common after valve

replacement surgery

y Drug effect or toxicity should beexcluded as potential causes

y Temporary pacing may beneeded depending on degree of AV block and HR as well asadequacy of lower escaperhythm

Mobitz type I

Mobitz type II

Complete AV block

y May be secondary tocardioplegia washout duringimmediate postoperative period

y Consequence of antiarrhythmicdrug therapy

y May be seen after valve

replacement secondary totrauma of surgical manipulationin the area of AV node or bundleof HIS

Conduction disturbances:

Complete AV block- Treatment:y Discontinuation of all potentially offending

y Therapy depends on underlying heart rateand adequacy of underlying ventricularescape rhythm

y Treated with temporary pacing , via

epicardial pacing wires

Complete AV blocky Factors which predict low likelihood of

recovery includey

calcified Aortic valvey delayed appearance of AV block

y significant preop conduction defect

y In absence of excessive calcification, and inpresence of a narrow complex escape rhythm

with a good heart rate, PPM placement maybe delayed up to 2 wks

Summary

AF is the most significant arrhythmia that occurs after cardiacsurgery.

It is associated with an increase in morbidity, length of hospital

stay, and mortality.

Patients who are at higher risk of postoperative AF should receiveprophylactic treatment.

AF usually resolves spontaneously after heart rate is controlled

Patients with AF of more than 48 hours should receiveantithrombotic therapy for thromboembolism prevention.

Thank yo

arrhythmias after cardiac surgery

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