Intraoperative arrhythmias are common, occurring in nearly 11% of patients under general anesthesia. They can be caused by preexisting cardiac conditions, medications, electrolyte abnormalities, procedures, or patient-specific factors. Bradyarrhythmias such as sinus bradycardia are usually treated pharmacologically with atropine or glycopyrrolate. Tachyarrhythmias like supraventricular tachycardia may require synchronized cardioversion. Ventricular arrhythmias should be promptly addressed and their underlying causes investigated and treated. Postoperative monitoring is important, especially for patients who required treatment for arrhythmias during surgery.

1. PERIOPERATIVE
ARRHYTHMIAS
KRISTEL QUITALEG, MD
DEPARTMENT OF
ANESTHESIOLOGY
REFERENCE: Arrhythmias during anesthesia by
Methangkool and Mahajan, (uptodate.com) last
updated January 2021

2. Intraoperative arrhythmias are common.
Nearly 11 % of patients experience abnormal HR or rhythm during GA.
Tachyarrhythmias:
HR >100 bpm
Bradyarrhythmias:
HR <60 bpm
Most: transient and
clinically insignificant
Some: indicate
underlying pathology
(eg, myocardial
ischemia, electrolyte
abnormalities)
Some: due to a
procedure-specific or
medication-specific
etiology
Occasionally: causes
intraoperative
hemodynamic
instability

3. Potential Contributing Factors
Preexisting
electrocardiographic
(ECG) abnormalities
Medication effects
Patient-specific
factors
Procedure-specific
factors

4. Preexisting electrocardiographic
(ECG) abnormalities
Preoperative
ECG
Prominent Q waves or
significant ST-segment
deviation
Chamber
abnormality/hypertrophy
QTc prolongation
Bundle branch block
(BBB)
Arrhythmias
Nonspecific changes (do
not necessarily increase
perioperative risk)
Ask:
Is the abnormality new or
old?
Does the patient have a
history of cardiovascular
disease?
Does the patient have
active cardiovascular
symptoms?
Is the planned procedure
elective, semi-urgent, or
urgent/emergency?
May
predispose
patient
to:
intraoperative arrhythmia
QTc prolongation
Bundle branch block
[BBB]
Wolff-Parkinson-White
[WPW] pattern)

5. Medication Effects
Increase risk for bradycardia
• Negative chronotropic agents: BBs,
CCBs, digoxin, amiodarone
• Anticholinesterases
• Sugammadex
• Opioids
• Vasoconstrictors: e.g., phenylephrine
May prolong QT interval
• Some increase risk of Torsades de
pointes (Tdp)
• While some do not.

6. …and cause Torsades de pointes (Tdp)

7. * Propofol and
neuromuscula
r blocking
agents have
NO known
effects on the
QT interval.

8. Patient-Specific Factors

11. Electrolyte abnormalities
Hypokalemia:
• <2.5 mmol/L: QT prolongation & arrhythmia
• <3.5 mmol/L: consider repletion (20 mEq via
central line TRF 1 hr, or if peripheral: TRF 2 hrs)
• Other arrhythmias:
• PACs, PVCs
• Sinus bradycardia
• AV blocks
• VT, VF
• Associated ECG changes:
• ST segment depression
• Decreased T wave amplitude
• Increased U wave amplitude
• Prolonged QT interval
Hyperkalemia:
• Can lead to:
• BBBs
• Bifascicular blocks
• Complete heart block
• Sinus bradycardia
• Arrest/asystole
• VT/VF
• Associated ECG changes:
• Peaked T wave, etc
• Many have ESRD.
• Avoid succinylcholine if potassium ≥5.5 mEq/L

13. Electrolyte abnormalities
Magnesium
• Hypomagnesemia: widens the QRS
complex, increases risk of Tdp,
sustained AF, frequent atrial or
ventricular ectopic beats, and other
ventricular arrhythmias
• Hypermagnesemia: If >4 mEq/L: may
cause conduction defects, bradycardia,
and hypotension
Calcium
• Hypocalcemia: prolongs the QT interval,
but has less potential to trigger TdP
compared with hypokalemia or
hypomagnesemia
• Hypercalcemia: shortens the
myocardial action potential, as
reflected in a shortened QT interval on
the electrocardiogram
• may mimic MI (ST segment elevation)

14. Other Patient-Specific Factors
Metabolic and
respiratory
abnormalities
• Hypoxemia
• Hypocarbia
• Hypercarbia
• Acid-base
disturbances
Intravascular volume
depletion
• Anemia, dehydration,
hypovolemia
• Typically results in
sinus tachycardia and
may lead to
development of other
arrhythmias.
Myocardial ischemia or
failure
• Atrial or ventricular
arrhythmias including
supraventricular
tachycardia (SVT),
conduction defect, or
ectopic ventricular
activity

15. Procedure-Specific Factors
Intrathoracic procedures
•If near the heart (eg, pulmonary or esophageal
surgery), contact with cardiac or pulmonary
venous structures may cause atrial or ventricular
ventricular arrhythmias
Intravascular interventions
•During insertion of a central venous catheter or
pulmonary artery catheter
•When the guidewire or catheter enters the RA:
RA: PACs, AF, or other SVTs may occur
•Upon entry into the RV: RBBB, PVCs, or VT may
may occur
Electroconvulsive therapy
Administration of local anesthetics
•LAST should be suspected id arrhythmias occur
shortly after administration of LA (eg, PNB).
•Typically, tachycardia and hypertension occur,
although bradycardia and hypotension have also
also been described.
•Can progress to ventricular arrhythmias and/or
asystole.

16. BRADYARRHYTMIAS

17. SINUS BRADYCARDIA
a slow HR <60 bpm but with normal atrial and
ventricular depolarization
Unique
intraoperative
causes:
Vagal reflexes
• Oculocardiac reflex during EOM
traction
• Peritoneal stretching
Neuraxial anesthesia
• With high T1-T4 blockade (cardiac
accelerator fibers)
Medications
Treatment:
Pharmacologic
• If severe with HR <40 bpm
• With transient episodes of asystole
• With signs of inadequate systemic
perfusion/hemodynamic instability
• If unstable: see algorithm
• If stable but <40 bpm
• IV glycopyrrolate in 0.2 mg
increments (up to 1 mg)
• Small incremental doses of atropine
0.2 mg
• For the transplanted heart: use a
positive chrontropic agent such as
isoproterenol or epinephrine

19. Temporary Pacing Options
Transcutaneous
pacing
Transvenous pacing
Pulmonary artery
catheter pacing

20. AV Blocks
FIRST DEGREE AV BLOCK: prolonged PR interval of 0.30
seconds, and a QRS complex of normal duration;
usually does not require treatment
MOBITZ TYPE I (WENCKEBACH) SECOND DEGREE AV BLOCK:
progressive prolongation of the PR interval until there is
a dropped ventricular beat (p wave without QRS)
MOBITZ TYPE II SECOND DEGREE AV BLOCK: constantly
prolonged PR intervals with occasional dropped
ventricular beats
THIRD DEGREE AV BLOCK: atrial impulses do not
conduct to the ventricles so that P waves are
discordant with QRS wave

21. Bundle Branch Blocks
LBBB RBBB Fascicular block
New onset of such blocks usually indicates either intrinsic cardiac disease or myocardial ischemia,
which should be rapidly addressed. Transient RBBB occasionally occurs during insertion of a PAC,
which may lead to complete heart block in a patient with a preexisting LBBB.

22. ASYSTOLE
Patients who develop
severe intraoperative
bradycardia are at risk for
progression to asystole or
pulseless electrical activity
requiring immediate
initiation of advanced
cardiac life support
(ACLS)

23. ATRIAL TACHY-
ARRHYTHMIAS
Atrial tachyarrhythmias with a heart rate (HR) >100 beats per
minute (bpm) are classified as having either a narrow QRS
complex (QRS duration of <120 ms) or a wide QRS complex
(QRS duration >120 ms)

24. SINUS TACHYCARDIA
most common atrial tachyarrhythmia during
anesthesia and surgery
Unique
intraoperative
causes:
Sympathetic stimulation
Hypovolemia/anemia
Others:
• Hypoxemia
• Hypercarbia
• Fever
• Sepsis
• Malignant Hyperthermia
Treatment:
Pharmacologic
• Usually treated with a short-
acting IV beta blocker to
decrease HR to <80 bpm if HR
is >120 bpm, or at a lower HR
(50-80 bpm) if the patient has
ischemic heart disease or
severe aortic or mitral
stenosis
• Esmolol bolus doses of 20 to
50 mg q2-3 mins
• Avoid BBs in patients with
significant hypovolemia, acute
acute hemorrhage,
decompensated CHF,
acute/severe bronchospastic
lung disease
If
recurrent
tachycardia:
Beta-blocker (if
appropriate)
• Esmolol infusion: 50-300
mcg/min
• Metoprolol 1-5 mg Iv boluses
• Labetalol 5-10 mg IV boluses
Deepen anesthesia
• Give adjuvants such as
opioids or dexmedetomidine

25. SUPRAVENTRICULAR TACHYCARDIA

26. ATRIAL FIBRILLATION
A HR >150 bpm is usually associated with
hypotension, while a HR <120 bpm may be
well tolerated.
Hemodynamic instability
with AF and rapid
ventricular response
(≥120 bpm)
• Immediate synchronized
cardioversion
• Consider sedation
• 120-200 J if biphasic, 200 J if
monophasic
Hemodynamic stability
with AF and rapid
ventricular response
(≥120 bpm)
• BB or CCB, rather than with
immediate cardioversion
• At risk for the development
of thrombi in the left atrial
appendage that may
embolize during or after
cardioversion
AF with nonrapid
ventricular response
(<120 bpm)
• If at risk to develop ischemia
or hemodynamic instability:
pharmacologic control of
ventricular rate
• BB: esmolol 10-25 mg or
metoprolol 1-5 mg, provided
BP is adequate
• CCB: verapamil/diltiazem
• Amiodarone: especially if
after cardioversion

27. Other Atrial Tachyarrhythmias
ATRIAL FLUTTER: typically with RVR of ≥150 bpm,
treatment is similar to AF
AVNRT (Atrioventricular Nodal Reentrant
Tachycardia): a paroxysmal SVT due to a reentry
circuit around the AV node; cardioversion should
be attempted in a hemodynamically unstable
patient who does not respond immediately to
vagal maneuvers and/or adenosine or CCB
treatment MULTIFOCAL ATRIAL TACHYCARDIA:
at least three distinct P wave
morphologies on ECG, with a rapid,
irregular atrial rate of >100 bpm;
Definitive treatment of MAT relies
on addressing the underlying
disorder.

28. Wide QRS Complex Tachyarrhythmias
Wide QRS ComplexSVT; Wolf-Parkinson White Syndrome

29. VENTRICULAR
ARRHYTHMIAS
Ventricular rhythms have a wide QRS complex (>120 ms). Possible causes should be investigated and
treated immediately, with particular attention to the “H's (ie, hypoxia, hypovolemia, acidosis [hydrogen
ion], hypo- or hyperkalemia, hypothermia) and T's" (ie, tension pneumothorax, cardiac tamponade, toxins,
pulmonary or coronary thrombosis)

30. VENTRICULAR
FIBRILLATION AND
PULSELESS VENTRICULAR
TACHYCARDIA

31. MONOMORPHIC VT WITH A PULSE
• Synchronized cardioversion: 100 J
• If necessary, myocardial perfusion is
augmented with infusion of a
vasoconstrictor: phenylephrine,
norepinephrine, or vasopressin
• Avoid epinephrine: may exacerbate
myocardial ischemia
• Once BP is adequate: amiodarone (150 mg
over 10 mins then maintenance of 1
mg/min x first 6 hrs) or procainamide or
sotalol may be administered
TORSADES DE POINTES
• Hemodynamically unstable: prompt
defibrillation and ACLS if pulseless, but
synchronized cardioversion may be
attempted if a diminished pulse is
visible with intra-arterial monitoring
• Hemodynamically stable:
Magnesium sulfate 2g as slow IV bolus

32. PREMATURE VENTRICULAR
CONTRACTIONS (PVCS)
• Common in the general population, even
in patients without cardiac disease
• If isolated: clinically insignificant
• If frequent: myocardial ischemia or
electrolyte abnormality
• Treatment: if symptomatic or frequent –
BBs or CCBs
• Frequent: >10,000/24 hrs, >10-15% of
total heart beats
NONSUSTAINED VT
• ≥3 consecutive ventricular beats are noted
on the ECG, at a rate >120 bpm but lasting
<30 seconds
• Hemodynamically stable: BB or CCB
• May also give amiodarone or lidocaine

33. POSTOPERATIVE MANAGEMENT
Continuous ECG monitoring in the
PACU
Cardiology consultation especially if:
• With myocardial ischemia
• New-onset AF
• Second- or third-degree AV block
• Ventricular tachycardia
• Required pharmacologic or other treatment

34. THANK YOU!
REFERENCE: Arrhythmias during anesthesia (Jan 2021) by Methangkool and Mahajan, uptodate.com