









































Texas Christian University 
“ The Science Behind the Art” 
Volume 12 - No.1 2024 

Anesthesia eJournal - Online
ISSN 2333-2611

Page 1

 Congenital Long QT Syndrome: A Cardiac Ion Channelopathy  
with Important Anesthetic Considerations 
David E. Harris, PhD, RN 

Affiliation:
University of New England School of Nurse Anesthesia  

Grant/Financial Support: 
None 

KEYWORDS:  Long QT syndrome, cardiac ion channel, Channelopathy

Abstract
Congenital long QT syndrome (cLQTS) is the most common genetic cardiac ion channelopathy in the US. Patients 
with cLQTS are at risk for ventricular tachycardia (VT) in the “torsades de pointes” (TdP) pattern from physical 
and emotional stress, including during the perioperative period. This narrative review outlines the history and 
pathophysiology of the most common types of cLQTS, describes treatments for cLQTS, discusses the experience of 
anesthesia providers with cLQTS, and reports recommendations for safe administration of anesthesia to these patients. 
No definitive guidelines exist for the anesthetic management of patients with cLQTS, therefore the anesthesia provider 
must rely on existing evidence to choose a safe anesthetic for this challenging patient population.

AEJ
Volume 12- No. 1 2024



Introduction
Congenital cardiac ion channelopathies are familial syndromes 
caused by mutations in the genes coding for cardiac ion channel 
proteins.1 Congenital long QT syndrome (cLQTS) is the most 
common congenital cardiac ion channelopathy in the US.2 It is 
present in apparently healthy patients with structurally normal 
hearts and can cause premature ventricular contractions (PVCs), 
initiating ventricular tachycardia (VT) in the “torsades de 
pointes” (TdP) pattern in which the QRS complex “twists” around 
the isoelectric line of the ECG. TdP can lead to ventricular 
fibrillation (VF) and sudden arrhythmic cardiac death (SCD).3 
The ventricular ectopy of cLQTS can be triggered by adrenergic 
stimulation, including from physical and emotional stress1, or 
during the perioperative period.4 
The likelihood of an anesthesia provider encountering a 
patient with LQTS may be increased due to:  1) some patients 
(including young children) with cLQTS benefit from implantable 
cardioverter defibrillators (ICDs)5 or cardiac sympathetic 
denervation6,7 and will need anesthesia for the device insertion 
or surgery8,9, and 2) people with one subtype of cLQTS (LQT1) 
are often born with congenital sensorineural deafness10 and may 
present for cochlear implants.11 
This paper is a narrative literature review of cLQTS focusing on 
the anesthesia implications of the most common types (LQT1 
through 3). cLQTS is of interest to anesthesia providers because 
patients with cLQTS may require anesthesia for any reason and 
for issues related to cLQTS, and because cLQTS can produce 
sudden cardiac death in the perioperative period. The goals of 
paper of this paper are to:

• Review the history and pathophysiology of cLQTS,
• Describe common treatments for cLQTS,
• Discuss the experience of anesthesia providers with patients

with cLQTS, and
• Report recommendations for safe administration of

anesthesia to these patients. 

Methods
Searches of MEDLINE (PubMed) and Google Scholar were 
conducted using the terms “congenital long QT syndrome”, 
“LQTS”, and “cardiac ion channelopathy” combined with 
“surgery” and “anesthesia”. Further relevant articles were identified 
from the bibliographies of these sources. A total of 215 articles 
were reviewed and 49 selected for inclusion based on relevance, 
scope, and unique information.   

Results
History of cLQTS: cLQTS was first described in 1957 when 
Jervell and Lange-Neilsen reported a family in which 4 of 6 
children had congenital deafness and “fainting spells”. Two of 
the children with fainting spells had prolonged QT intervals 
and three died suddenly but had no structural cardiac defects on 
autopsy.12 In 1964, ECG and genogram analysis of children in 
“schools for the deaf ” showed that the syndrome of congenital 
deafness, prolonged QT interval, and high risk of sudden cardiac 
death was inherited in an autosomal recessive pattern.13 Another 
family with a history of sudden cardiac death across multiple 
generations and 3 siblings who had syncopal attacks, prolonged 

QT intervals, but normal hearing was described by Romano in 
1965. The normal hearing and multi-generational presentation 
in this family suggested a distinct autosomal dominant form of 
cLQTS.14 
There are 17 known subtypes of cLQTS (LQT1 – LQT17).3,15 
The genes responsible for the most common types of cLQTS 
(LQT1 – LQT3) were identified in the 1990s. In 1995 a gene 
(KCNH2) coding for the cardiac voltage-gated potassium channel 
which produces the rapid potassium repolarization current (IKr) 
was found responsible for LQT216 and a gene (SCN5A) coding 
for cardiac voltage-gated sodium channel responsible for the 
depolarization current (INA) was found responsible for LQT3.17 
A gene (KCNQ1) for the voltage-gated potassium channel 
producing the slow potassium repolarization current (IKs) was 
determined responsible for LQT1 in 1997.18 Subsequently, 
the genes responsible for rarer types of cLQTS have been 
identified.3,15,19,20,21,22 
cLQTS in the general population: The prevalence of cLQTS is 
1/2000 live births.23 Patients with cLQTS are often identified 
via genetic testing when a family member is diagnosed. They are 
also diagnosed after episodes of syncope, palpitations, or even 
after surviving sudden cardiac arrest.2 If symptomatic, people 
with cLQTS are usually diagnosed as children, but they may 
be asymptomatic and undiagnosed well into adulthood.24 Thus, 
patients with both diagnosed and undiagnosed cLQTS present 
for anesthesia. 
The triggers for TdP differ by cLQTS subtype. For patients with 
LQT1, adolescent and preadolescent males are at greatest risk for 
TdP, which is often triggered by exercise, including swimming. In 
LQT2, adult female patients are most at risk for TdP, particularly 
in the postpartum period and when exposed to sudden alarming 
auditory stimuli. For LQT3, adult males are at greatest risk and 
TdP commonly occurs during rest or sleep.3,25 As many as one 
in five untreated patients with symptomatic cLQTS die within 
a year but the mortality rate falls to 1% over 15 years with 
appropriate therapy.2 
Electrophysiology of cLQTS: The action potential in ventricular 
cardiac muscle is divided into phases. Beginning at a resting 
membrane potential of ~ -96 mv, phase 0 is a rapid depolarization 
to ~ +20 mv caused by the opening of voltage-gated Na+ 
channels. During phase 1 there is a slight repolarization as Na+ 
channels close. This repolarization is interrupted by the opening 
of slow, long acting, voltage-gated (L-type) Ca++ channels. This 
produces phase 2, a prolonged plateau at ~ +10 mv during which 
the depolarizing calcium current is balanced by the repolarizing 
rapid and slow potassium currents (Ikr and IKs). Next the L-type 
Ca++ channels close and current flow through K+ channels 
increases. This causes a rapid repolarization (phase 3) that 
reestablishes the resting membrane potential (phase 4).1,25,26 On 
the ECG, the QT interval is measured from the beginning of the 
QRS complex (ventricular depolarization) to the end of the T 
wave (ventricular reoperation).26 However, because depolarization 
and repolarization are brief events, most of the QT interval 
reflects the plateau of phase 2.1 Any channelopathy that prolongs 
the plateau will lengthen the QT interval.  
LQT1, 2, and 3 account for 75 to 85% of cLQTS cases.2,27 The 
remaining variants (LQT4 – LQT17) are each responsible for 
≤1% of cases.28 LQT1 and LQT2 are caused by loss of function 

Texas Christian University 
“ The Science Behind the Art” 
Volume 12 - No.1 2024 

Anesthesia eJournal - Online 
ISSN 2333-2611

Page 2



mutations to genes (KCNQ1 and KCNH2) coding for the K+ 
channels responsible for the IKs and IKr currents that cause 
cardiac repolarization. These mutations delay repolarization. 
LQT3 is caused a gain of function mutation in the gene (SCN5A) 
coding for the Na+ channel responsible for the depolarizing INA 
current. This mutation delays inactivation of the channel. All 
three prolong phase 2 of the cardiac action potential and the QT 
interval.15,27 
Voltage gated ion channels, including the L-type Ca++ channel, 
generally enter a refractory period after closing. Normally, by 
the time the L-type Ca++ channel leaves its refractory state the 
cardiac myocyte membrane has repolarized and the channel is 
not reactivated. However, in patients with cLQTS, the L-type 
Ca++ channels of some cardiac myocytes leave their refractory 
period before the end of the prolonged plateau phase when the 
membrane is still depolarized. The L-type Ca++ channels are 
reactivated in a process known as an “early afterdepolarization” 
and cause a premature ventricular contraction (PVC).1,2,27 
Because different areas of the ventricular myocardium repolarize 
at different rates, a single PVC can give rise to VT via a reentry 
mechanism. This VT takes the form of TdP as the depolarization 
pathway circling the ventricle changes.2,28 
Sympathetic stimulation, with its tachycardia, put patients with 
cLQTS, particularly those with LQT1 and 2, at risk for TdP. In 
the normal heart, sympathetic stimulation activates potassium 
channels responsible for the IKs current and repolarization so that 
the duration of the cardiac action potential, and the QT interval, 
shorten as the heart rate increases and the RR interval decreases. 
(The RR interval is the time, in seconds, between consecutive R 
waves.) This allows the myocardium to repolarize fully before the 
next normal depolarization occurs. However, in LQT1 the channel 
responsible for IKs does not respond to sympathetic stimulation, 
the QT interval is not shortened as heart rate increases, parts of 
the myocardium remain depolarized, and L-type calcium channels 
can cause early afterdepolarizations giving rise to TdP. The normal 
inverse relationship between the QT interval and the heart rate 
also explains why the raw QT interval length must be corrected 
for heart rate to assess if the QT interval is prolonged.1,25 
Diagnosis of cLQTS: The possibility of cLQTS should be 
investigated in patients with QT intervals corrected for heart 
rate (QTc) calculated using the Bazett formula (QTc=QT/ √RR 
interval) > 440 ms for males and > 460 ms for females (normal 
values). A definitive diagnosis is based on the extent of QTc 
prolongation and also requires consideration of other ECG 
issues (abnormal T waves or a history of TdP), clinical history 
of episodes suggesting cLQTS (syncope or palpitations), and 
family history of cLQTS or sudden cardiac death. The “Schwartz 
Criteria” delivers a diagnostic score based on these criteria and 
the anesthesia provider should consult the following references 
for a full understanding of how this score is determined.2,24,25,26 
However 20-25% of patients with cLQTS confirmed by genetic 
testing have normal QT intervals.23 A QTc>500 ms strongly 
predicts cLQTS in asymptomatic patients with no significant 
family history.25 
Variation in T wave morphology, variability in the QT interval, 
and prolongation of the T wave all reflect abnormal and varying 
cardiac repolarization rates among different regions of the 
myocardium and are associated with TdP risk.25,29 One measure 

of abnormal and prolonged repolarization, increased transmural 
dispersion of repolarization (TDR), is quantified as the time 
from the peak of the T wave to its end (TPE). A prolonged TPE 
may actually reflect TdP risk more accurately than QTc alone 
in patients with cLQTS.26 Values indicating elevated TPE are 
disease dependent but TPE>113 ms indicates arrhythmia risk in 
the general population.25

Management of cLQTS: Management includes avoiding triggers 
specific for the patient’s cLQTS type and medications that 
prolong the QT interval.3,23  QT prolonging antiarrhythmic 
medications include the class IA antiarrhythmics that slow 
conduction through the depolarized myocardium and block 
the IKr current (e.g. quinidine and procainamide) and the class 
III antiarrhythmics that also block the IKr (including ibutilide 
and the nonselective beta blocking medication sotalol).25.26 

Amiodarone, a class III antiarrhythmic medication, and verapamil, 
a calcium channel blocking medication, prolong the QTc and 
should be avoided in patients with cLQTS25 but produce a lower 
risk of TdP, probably because they do not increase TDR.11,26 
For a full list of medications that prolong the QT interval see 
www.crediblemeds.org. A discussion of the impact of common 
perianesthetic agents on the QT interval is included in the section 
on “Induction & maintenance of anesthesia” below.
Long-acting ß receptor antagonists are the mainstay of cLQTS 
medical treatment.3,23 However, they may be more effective for 
patients with LQT1, where they almost completely eliminate 
TdP episodes, than in LQT2 and 3.2 Sodium channel blocking 
medications (e.g. mexiletine) can be added to beta blocking 
therapy for some patients with LQT3.23 Their efficacy may depend 
on the patient’s specific mutation.2 
Implantable cardioverter defibrillators (ICDs) are recommended 
for patients with cLQTS who have survived an episode of 
SCD or who continue to experience syncope despite ß receptor 
antagonists. But they are not without complications, including 
inappropriate shocks and the necessity of periodic additional 
procedures.3,5,23,30 

First evaluated in 1991, left cardiac sympathetic denervation 
(LCSD) also shortens the QTc and can prevent episodes of 
TdP in 50% or more of symptomatic patients with cLQTS.6,30 
LCSD is used for patients with cLQTS who remain symptomatic 
on optimized beta blocking therapy and for young children 
who are at higher risk for complications of ICD insertion.23 
The procedure is generally performed with the patient in the 
right lateral decubitus position. It can be accomplished either 
with thoracotomy or via minimally invasive video-assisted 
thoracoscopic surgery (VATS) but one-lung ventilation is usually 
required.30,31

The mechanism by which LCSD reduces arrhythmias in 
patients with cLQTS is multifaceted. LCSD prevents efferent 
adrenergic outflow to the heart from the left sympathetic ganglia, 
reducing tachycardia and increasing the electrical stability of 
the myocardium. It also may increase parasympathetic cardiac 
efferent activity both by removing the sympathetic cardiac afferent 
pathways that usually inhibit it and by preventing release of the 
long-acting cardiac sympathetic co-transmitter neuropeptide Y 
(NPY), an inhibitor of postganglionic parasympathetic cardiac 
acetylcholine release.7 

Texas Christian University 
“The Science Behind the Art” 
Volume 12 - No.1 2024 

Anesthesia eJournal - Online 
ISSN 2333-2611

Page 3



Discussion
While there are no definitive guidelines for the anesthetic 
management of patients with cLQTS, much can be learned from 
case studies and the recommendations of authoritative review 
articles. 
Preoperative period: Patients with diagnosed cLQTS requiring 
anesthesia will usually, but not always, be receiving ß receptor 
antagonists preoperatively.32,33 These medications must be 
continued on the day of surgery25, a precaution that has been 
called the most important preoperative intervention to reduce 
perioperative TdP risk in cLQTS, although adherence is not 
absolute.33 
During the immediate preoperative period, patients with 
cLQTS should be maintained in quiet, warm surroundings and 
should receive adequate preoperative medication to reduce the 
sympathetic activity that accompanies anxiety.11,25 For pediatric 
patients with cLQTS, anxiolysis has been accomplished with 
midazolam.34,35,36 Additional preoperative precautions for patients 
with cLQTS include cardiology consultation and scrutiny of 
the 12-lead ECG (including measurement of a baseline QTc), 
correction of electrolyte imbalances that can lengthen the QT 
interval (e,g, hypokalemia, hypomagnesemia, and hypocalcemia) 
and the placement of external defibrillator pads.11,25 
Patients with cLQTS who have ICDs should have the device’s 
function checked by a cardiologist.25,35,37 The importance of this 
precaution is illustrated by the case of a 7-year-old child with 
LQT2 and an ICD who presented for myringotomy. After general 
anesthesia was induced with sevoflurane the patient developed 
TdP but the ICD failed to function. The child was successfully 
defibrillated with an external defibrillator and the surgical 
procedure was cancelled. A postoperative chest x-ray revealed a 
fractured ICD wire.36 

Intraoperatively, electromagnetic interference in the function of 
an ICD, particularly the use of monopolar electrosurgery superior 
to the umbilicus, is a concern.38 ICDs can be left on if the surgery 
allows35 but turning off the antitachyarrhythmia functions of an 
ICD can prevent unnecessary shocks.38 In some centers, ICDs 
are turned off for patients with cLQTS who are not pacemaker 
dependent once defibrillator pads and cardiac monitoring are 
instituted before induction.34 
Induction & maintenance of anesthesia: General anesthesia may 
prolong the QT interval even in patients without cLQTS39 
possibly because hypothermia and positive pressure ventilation 
both prolong the QTc.11 Neuraxial anesthesia has been used 
successfully in patients with cLQTS, including LQT240, although 
it also may prolong the QTc.39 During neuraxial anesthesia, the 
QTc prolonging effects of local anesthetic agents mostly occur if 
the drugs enter the systemic circulation at high levels.41 Epidural 
anesthesia, which allows the gradual establishment of the desired 
level of sympathetic block to avoid hypotension, may be safer than 
“one shot” spinal blocks4,37 and epidural catheter insertion for intra 
and postoperative analgesia has also been successful.35  
Among intravenous (IV) anesthetic agents, ketamine increases 
the QTc and TdP risk via its sympathomimetic properties and 
should be avoided in patients with LTQS. Propofol, midazolam, 
and fentanyl (and fentanyl analogues) do not increase QTc 
significantly and have all been used effectively. Halogenated 
volatile anesthetics generally increase the QTc by blocking the IKr 

and IKs currents responsible for repolarization.25,42,43,44 Sevoflurane 
has seen extensive use in patients with cLQTS. However, even 
sevoflurane is listed among medications that prolong the QTc 
increasing TdP risk25,29, and expert consensus on the management 
of patients with cLQTS recommends avoiding all QTc prolonging 
medications.23 
Two centers that regularly perform cochlear implant surgery 
report the use of total IV anesthesia (TIVA) with propofol, 
fentanyl (or an analogue), and a nondepolarizing muscle 
relaxant either exclusively45 or preferentially11 for patients with 
cLQTS (presumably mostly LQT1 and all patients ≤ 8 years of 
age) undergoing these procedures. Potentially life-threatening 
perioperative arrhythmias occurred in 5 of the 45 (11%) cases in 
these two series, all of which were treated successfully with cardiac 
pacing. Practitioners in these (and other) centers also administer 
magnesium IV prophylactically in this patient population to block 
calcium currents and reduce TdP risk.4,11,35,45 Suxamethonium 
should not be used because it induces potassium shifts and causes 
sympathetic stimulation. Pancuronium is also a poor choice 
for a muscle relaxant for patients with cLQTS because of its 
parasympathetic blocking properties.11

Two case series of pediatric patients with cLQTS undergoing 
general anesthesia for a range of procedures, some of which were 
LQTS-related (eg, ICD insertion), may provide more 
generalizable results. A total of 179 patients underwent 272 
procedures and 194 of these encounters (71%) involved exposure 
to inhalation anesthetics. Adverse events including TdP occurred 
during 8/272 (3%) of these procedures. Five of these adverse 
events occurred in patients undergoing LQTS-related procedures, 
including 3 TdP episodes in neonates in the first day of life.32,33 
In a case series of 22 patients ages 1 month to 17 years undergoing 
LCSD with general anesthesia (20 of whom had cLQTS) 
sevoflurane was employed as the induction agent for 11 (50%) 
while 10 (45%) received propofol. Anesthesia was maintained with 
inhalation agents (predominantly isoflurane) in 19/22 = 86% of 
cases. No anesthetic complications occurred.35 The apparent low 
risk of sevoflurane for patients with cLQTS may be explained 
by the results of a randomized controlled study that assigned 
healthy children (age 1-16 years) scheduled for elective surgery to 
receive either TIVA with propofol or inhalation anesthesia with 
sevoflurane. Propofol increased neither the QTc nor the TDR as 
measured by TPE. Sevoflurane increased the QTC but not the 
TPE.33

Sevoflurane was also employed for anesthetic induction for 
a 17-month-old patient with cLQTS (presumably LQT1) 
undergoing cochlear implants47 and an 11-year-old patient with 
epilepsy and LQT2 undergoing an MRI.47 In both cases, the 
airway was secured following the administration of propofol 
IV and general anesthesia was maintained with sevoflurane 
and propofol. No anesthetic complications occurred. Similarly, 
a 5-year-old undergoing LCSD had anesthesia induced and 
underwent tracheal intubation following administration of 
fentanyl, propofol, and a nondepolarizing muscle relaxant. 
Anesthesia was maintained with sevoflurane, fentanyl, and an 
epidural block without incident. (These cases also highlight 
the importance of suppressing the sympathetic response to 
laryngoscopy with adequate IV medications including propofol 
and fentanyl or an analogue.11,43)

Texas Christian University 
“ The Science Behind the Art” 
Volume 12 - No.1 2024 

Anesthesia eJournal - Online 
ISSN 2333-2611

Page 4



Sevoflurane anesthesia has been associated with TdP in patients 
with cLQTS, however. The 7-year-old patient with LQT2 who 
developed TdP after sevoflurane induction was described above.37 
Similarly, an adult with LQT2 experienced TdP during anesthesia 
with sevoflurane. As in the pediatric case, TdP for this adult was 
terminated with external defibrillation. Then magnesium sulfate 
was administered IV, and an isoproterenol infusion (shortens the 
QTc) begun. The patient’s QTc was 497 ms preoperatively, 534 
ms on the morning of postoperative day 1, and 495 ms later that 
day. The patient subsequently revealed that they had not taken 
prescribed ß receptor antagonists for 2 days before surgery.44 There 
is also a report of 4-year-old patient with undiagnosed cLQTs 
undergoing surgical correction of velopharyngeal dysfunction. 
While the patient was under sevoflurane anesthesia, the surgeon 
injected 1 ml of 1% lidocaine with 1:100,000 epinephrine into the 
surgical field, the patient’s heart rate increased from 113 bpm to 
175 bpm, and TdP developed – which resolved spontaneously in 
60 seconds.48 This case illustrates why some authors suggest that 
local anesthetics with epinephrine are contraindicated in patients 
with cLQTS.25

Treatment of intraoperative TdP: If TdP does develop in patients 
with cLQTS under anesthesia the provider should discontinue the 
use of QT-prolonging medications (e.g. switch from inhalation 
anesthesia to TIVA) and treat with IV magnesium sulfate, ß 
receptor antagonists (e.g. esmolol), and lidocaine, as well as cardiac 
pacing if needed.4,11,25,37,43 (The equipment to establish transvenous 
cardiac pacing/ defibrillation should be available in the OR prior 
to induction.11) If TdP deteriorates into VF, standard resuscitation 
including external defibrillation has been used successfully.37,45 
Emergence from anesthesia: Three patients, ages 11 to 15 years, 
with cLQTS developed arrhythmias (2 including VT) during 
emergence from general anesthesia with inhalation agents 
and directly after receiving anticholinesterase/ anticholinergic 
medications to reverse nondepolarizing neuromuscular blockage 
as well as ondansetron as prophylaxis against postoperative 
nausea and vomiting (PONV). All were treated successfully with 
ß receptor antagonists and/or lidocaine.32 Anticholinesterase/ 
anticholinergic drug combinations as well as the antiemetics 
ondansetron and droperidol carry TdP risk for patients 
with cLQTS.25,29 Dexamethasone has been used safely as an 
antiemetic.11,35,47 Sugammadex does not substantially prolong the 
QTc – at least among healthy patients.25

The importance of preventing PONV in patients with cLQTS 
is illustrated by the case of an adult patient with syncope but no 
known cLQTS. This patient suffered from chronic diarrhea and 
was scheduled for esophagogastroduodenoscopy under monitored 
anesthesia care. After an uneventful procedure, the patient 
experienced PONV in the post anesthesia care unit (PACU) 
and received ondansetron and promethazine. About 1 hour later 
they developed a tachycardia (later identified as TdP) and then 
pulseless ventricular fibrillation, successfully treated with chest 
compressions and defibrillation. After resuscitation, the cQT was 
>600 ms and the serum potassium = 2.4 mmol/L. The patient
received magnesium and potassium replacement IV.49 The initial
symptom of diarrhea, the pre-procedure bowel prep, and the
PONV may all have contributed to the hypokalemia that sparked
this episode. 

Summary and conclusions
Patients with cLQTS are a high-risk population and require 
special anesthetic precautions. The findings of this narrative review 
can be summarized as follows:

• The most common types of cLQTS (LQT1-3) are caused by
defects in genes coding for myocardial potassium or sodium
channels. They cause delayed repolarization, a prolonged QTc, 
a prolonged TPE, and an elevated risk of sudden cardiac
death.

• cLQTS is diagnosed with the Schwartz Criteria and treated
with ß receptor antagonists, ICDs, and LCSD.

• Pre-anesthetic precautions include the following:
o Consider cardiology consultation,
o Have function of the ICD (if present) checked,
o Determine baseline QTc,
o Correct any electrolyte imbalances, 
o Premedicate to prevent anxiety, 
o Use of a warm, quiet preoperative waiting area, and
o Continue ß receptor antagonists on the day of surgery. 

• Intraoperative, the anesthesia provider should:
o Apply external defibrillator pads and all standard

monitors prior to induction,
o Turn off ICD or adjust its settings to avoid

electromagnetic interference, 
o Monitor the QT interval,
o Have magnesium salts ready for administration if TdP

develops and consider prophylactic administration for
high-risk patients, 

o Consider TIVA and consider the use of sevoflurane if
an inhalation agent is needed, 

o Use propofol and/or fentanyl (or an analogue) to blunt
the sympathetic response of airway manipulation,

o Avoid ketamine, suxamethonium, and pancuronium, 
and

o Maintain normothermia and avoid high inspiratory
pressures.

• If TdP does develop, the anesthesia provider should be
prepared to:

o Give magnesium salts IV,
o Consider administration of ß receptor antagonists and

lidocaine, 
o Initiate cardiac pacing if pharmacologic treatment

unsuccessful, and
o Initiate standard resuscitation including defibrillation

if needed.
• During emergence for anesthesia and in the PACU, the

provider should:
o Consider alternatives to anticholinesterase/

anticholinergic drug combinations,
o Avoid droperidol or ondansetron but consider the use

of dexamethasone as prophylaxis against PONV,
o Maintain the patient in a warm, quiet environment,
o Be aware that TdP may occur in the PACU.

Texas Christian University 
“ The Science Behind the Art” 
Volume 12 - No.1 2024 



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SUMMARY OF KEY POINTS 

• The most common types of cLQTS (LQT1-3) are caused by defects in genes coding for myocardial potassium or sodium
channels. Patients with cLQTS are at risk for VT in the TdP pattern from adrenergic stimulation, including that which occurs
during the perioperative period. 
• cLQTS is diagnosed using the Schwartz Criteria and treated with ß receptor antagonists, ICDs, and LCSD.
• Pre-anesthetic precautions include cardiology consult, determining a baseline QTc, correcting electrolyte imbalances, 
premedicating to prevent anxiety, using a warm quite preoperative waiting area, and continuing beta blocking medications on the
day of surgery.
• Intraoperative precautions include applying external defibrillation pads and all monitors prior to induction, ensuring that no
electromagnetic interference occurs to the ICD, monitoring the QT interval, avoiding medications that prolong the QT interval, 
blunting the adrenergic response to laryngoscopy with adequate medication, considering TIVA but favoring the use of sevoflurane
if an inhalation agent is required, maintaining normothermia, avoiding high inspiratory pressures, and being prepared to administer
magnesium salts IV if TdP develops. 
• During emergence from anesthesia the provider should consider alternatives to anticholinesterase/ anticholinergic drug
combinations, consider the use of dexamethasone as prophylaxis against PONV, maintain the patient in a warm, quiet environment, 
and be aware that TdP may occur in the PACU.

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