Intraoperative Cardiac Arrhythmias

Intraoperative Cardiac Arrhythmias

Amy Harbeck, CRNA, DPS

References:

Stoelting, R., Hines, R., & Marschall, K. (2013). Handbook for Stoelting's anesthesia and co-existing disease. Philadelphia, PA: Elsevier/Saunders. Chapter 4

Objectives:

• Identify abnormal EKG
• Develop a plan of care for patients with chronic abnormal EKG
• Develop a plan of care for patients with acute abnormal EKG

Last but not least....

Positive Pressure ventilation:cardiac effects

Increases intrathoracic pressure which reduces venous return and preload, causing decrease in CO.

Changes in the partial pressure of carbon dioxide (PaCO2) resulting from changes in ventilation will also have cardiovascular effects.

A low PaCO2, which commonly occurs during controlled ventilation, causes peripheral vasoconstriction by a direct effect.

This increases systemic vascular resistance, increases afterload and can result in a fall in cardiac output

ICU vs. OR

Operating Room

Volatile Anesthesia Agents: Beneficial effects

In ICU...

All volatile anesthetics:

depress cardiac contractility

by decreasing the entry of Ca++ into cells during Depolarization

Phase 2 (plateau phase) of the cardiac cycle

Most volatile anesthetic agents are coronary vasodilators

Volatile agents appear to exert beneficial effects in the setting of myocardial ischemia and infarction

**They reduce myocardial oxygen requirements

Surgery

• Pain
• Blood Loss
• Electrolyte Imbalance

Co-existing Diseases

Critically ill patients coming to the OR..

• What medications should be continued in the OR from ICU?

Anesthesia:

• Prevent/relieve pain
• Induce anesthesia
• Maintain anesthesia
• Maintain hemodynamic status

Atrial Fibrillation

Cardiac Failure

Massive MI

Severe CHF

Failing Heart...waiting for transplant

Trauma

Shock states

Neurological

What meds are we used to using:

Epinephrine

Levophed

Dopamine/Dobutamine

Can be an acute or chronic condition!

Predisposing conditions:

• Rheumatic heart disease (MV disease)
• HTN
• Thyrotoxicosis
• Ischemic heart disease
• COPD
• Acute ETOH intoxication
• Pericarditis
• PE
• Atrial septal defect

Most significant clinical consequence is stroke!!

Nitrous Oxide

In Vitro: theoretically depresses myocardial contractility

However, CO, BP and HR remain unchanged.

Very good adjunct anesthetic….

For the right procedure and patient

A ventricular focus can be made irritable by

New-Onset

A-Fibrillation

Ventricular Tachycardia Intraoperatively

Consider...

• Low 02

Airway obstruction

Absence of air

Near drowning

Suffocation

• Air with poor 02 content
• Minimal oxygenation in lungs

Pulmonary embolus

Pneumothorax

• Reduced cardiac output

Hypovolemic

Cardiogenic shock

• Poor to absent coronary blood supply

Coronary insufficiency

Infarction

• Low K+

Reduced serum potassium (hypokalemia)

And to a lesser degree, epinephrine-like substances

(Beta 1 adrenergic stimulants)

• Pre-operative EKG
• Thorough mediation list/discussion
• Do we need a cardiac consult?
• Do we have a baseline EKG?
• Electrolytes important when considering co-morbidities

What are types of Cardiac issues?

Anesthetic management:

• Surgery should be postponed if possible
• Management depends on hemodynamic stability of patient
• If the AF is causing hemodynamic instability - cardioversion is appropriate
• If stable patient - goal is rate control with BB or CCB
• AF is the most common post-operative tachyarrhythmia usually occurring within 2-4 days

• Defined as 3 or more consecutive PVC's occurring at a heart rate of >120 bpm

Cardiac dysrhythmias:

• Classified according to heart rate and site of the abnormality

Conduction disturbances:

• Classified by site and

degree of blockade

The effects on patient?

Clinical significance depends on effects to vital signs and potential for deterioration into a life threatening rhythm

Healthy patients = compensate

Unhealthy cardiac patients= compensatory mechanisms are disrupted by anesthesia, end result can be catastrophic

A few common arrhythmia's...

Prognosis depends on presence or absence of structural heart disease!

Stop the case!!! May need to bring back another time!

Isoflurane

Physiologic increases in Sympathetic tone:

Pain

Intubation/laryngoscopy

Surgical pain

Light anesthesia

Fever/Infection

Anxiety/Fear

Hypovolemia

NPO/Bowel Prep

Hypoglycemia

Hypotension

Operative bleeding - anemia

Arterial Hypoxemia

Drug Induced Tachycardia

Atropine

Glycopyrrolate

Sympathomimetic drugs

Caffeine

Nicotine

Cocaine

Amphetamines

Pathologic Increases in Sympathetic Tone

Myocardial ischemia/infarction

CHF

PE

Hyperthyroidism

Pericarditis

Pericardial Tamponade

MH

ETOH withdrawal

Tachydysrhythmias

Sinus Tachycardia:

Why could this happen in an acute operative setting?

Name 5 causes....

Sinus Tachycardia in the Operative Setting

Three Mechanisms:

1. Increased automaticity in the normal conduction tissue OR an ectopic focus

2. Reentry via abnormal pathways

3. Triggering of abnormal cardiac potentials due to "afterdepolarizations"

VT or SVT??

Depresses sinoatrial node automaticity

Dilates coronary arteries

(but is not as potent as Nitroglycerin or Adenosine)

How is cardiac output maintained?

Increased HR

Conflicting studies about whether coronary steal causes regional myocardial ischemia during episodes of tachycardia or drops in BP

Coronary Steal:

When a drug is given to a person with partial obstruction in a coronary artery, all the coronary vessels dilate. Hence blood will flow preferentially to the non-obstructed vessels, reducing the flow in the region of the obstructed vessel. Hence the drug given to improve the circulation will predispose to stealing of the blood into other regions.

Perioperative Ectopy

Chronic Atrial Fibrillation

Can be hard to determine...

if unstable - cardioversion!

Pre-Operative Considerations

Desflurane

• PVCs, PACs, PJCs, Dysrhythmias
• Common
• Determine cause
• Consider supply and demand
• Treat appropriately
• See tachycardia and ischemia treatment

Judgement:

Is it acceptable?

Does the patient continue to be hemodynamically stable with arrhythmia?

• Most common sustained cardiac dysrhythmia in the general population, affects 2.2 million Americans
• Most common underlying CV diseases associated with AF are systemic HTN & ischemic HD
• Long term A-fib increases risk of CHF
• Loss of atrial kick
• Anticoagulation - what are the implications?

Similar cardiac effects to those of Isoflurane

Dose related Increase in BP but Decrease in SVR

Minimal CO effects with 1-2 MAC

Does not cause increased coronary blood flow (such as Isoflurane)

Rapid Increased MAC –Inc. BP, HR, and catecholamine levels

Tx: Narcotics and Esmolol

Sevoflurane

Mildly depresses cardiac contractility

Less decrease in SVR and BP than Iso or Des

Little increase in HR

No evidence of coronary steal

May prolong Q-T interval

Anesthesia Pre-operative evaluation: who is at risk for cardiac events?

Local anesthetics

Adjuncts

What could cause pre-operative arrhythmias?

Cardiac effects of Local:

Can depress the contractility and conduction

High concentrations depresses conduction by binding to fast sodium channels.

Many uses during surgery: local injection by surgeon, IV to block intubation response, regional blockade or neuraxial anesthesia

High spinal with cardiac arrest: high incidence, even in healthy patients - Tx is supportive measures

Local with Epinephrine (and or cocaine) during ENT/oral surgery

Be careful with patients with stenotic valvular lesions

and epinephrine ~ causes tachycardia!

Fentanyl/Morphine type opioids

In general do not affect cardiac function

Vagal mediated bradycardia

***Meperidine may increase HR, structurally similar to Atropine

Benzodiazepines: variable HR seen with

induction suggests may alter vagal tone

Ketamine: Increases arterial BP, HR and CO

Increases Cardiac Workload, avoid in CHF and patients with uncontrolled hypertension.

-Anxiety

-Patient is non-compliant with medications

-Patient stops cardiac medications prior to surgery thinking that they may interfere with anesthesia

History?

Hypertension, CAD, MI, Cardiomyopathy, Chronic Chest Pain?

Medications?

Lasix, Digoxin, Metoprolol, Nitroglycerin, Lisinopril, Cardizem, etc....?

Type of surgery?

Preparing for surgery?

NPO - how long?

Bowel preparations?

Any medications held?

The more risk factors the increased chance of poor outcome

Sinus Bradycardia

Vagal stimulation:

• Laryngoscopy

Surgical Stimulation:

• Eye surgery
• Uterine surgery
• Carotid artery surgery
• insufflation of abdomen

Caused by volatile anesthetic/or repeat doses of Succinylcholine

Treatment

Succinylcholine

Beta-Blockers

Management of Anesthesia

• Only required if symptomatic
• mildly symptomatic - eliminate cause
• severely symptomatic - Atropine 0.5mg IV Q3-5min
• Initiate pacing
• Epinephrine &/or Dopamine infusion while waiting for pacemaker
• Glucagon 3mg IV= reversal for Beta-blocker or Calcium Channel blocker overdose that is unresponsive to Atropine. Follow with Glucagon infusion at 3mg/hr

ST Diagnosis & Treatment

What type of drug is this?

Depolarizing Skeletal Muscle Relaxant

Cardiac Effects:

Slight increased HR

Be careful of repeated doses=bradycardia

Thought to be due to its metabolite succinylmonocholine which stimulates cholinergic receptors in the SA node

What is the main cause of succinylcholine induced arrhythmias?

A normal intubating dose causes the K+ levels to increase by 0.5 to 1 mEq/L

Not a problem with normokalemic patients but conditions which predispose patients to an increase in potassium

this increase could be fatal!

Labetalol:

5-20 mg IV over 2 minutes - reassess

Total dose not to exceed 300mg

* very unusual to give this large dose in anesthetized pt.

Metoprolol:

Acute Tachyarrhythmia - 5 mg IV over 1-2 min; total dose not to exceed 15mg

Afib/Flutter or SVT:

2.5 mg - 5mg IV Q2-5min; not to exceed 15 mg over 10-15 min

(Medscape App)

• Apply or increase Oxygen concentration:
• increase supply due to increased demand
• Avoid vagolytic drugs (such as Pancuronium)- don't want to block vagal nerve impulse

HR of 100-160

Normal P waves before every QRS

Normal PR interval

Treatment aimed at correcting underlying cause if increased sympathetic stimulation!

If not related to hypovolemia or compensation for maintaining CO ..... may be appropriate to give a Beta-Blocker

Untreated ST contributes to myocardial ischemia and CHF in susceptible patients

Labetalol:

• Effective in treating mild, moderate, and severe hypertension.
• It is alpha-1-selective, but beta-nonselective; its ratio of beta- to alpha-adrenergic blocking potency is

7:1 with IV administration

• Better for treating high blood pressure than decreasing heart rate

Metoprolol: Selective inhibitor of alpha-1 adrenergic receptors; competitively binds with beta-1 receptors; little or no effect on beta-2

Better for treating HR than BP

• Many causes clinically obvious - treat appropriately; IVF, PRBC, pain control, anxiolytics, deepen your anesthetic
• Less obvious are the underlying causes such as:
• infection
• hypoxia
• MI
• CHF