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directed therapy is under investigation as a future treatment periodic fetal scalp sampling may be the only way to ade-
option. Any episode of TdP should be treated by cardioversion, quately diagnose fetal distress. Neonatal bradycardia and hypo-
defibrillation, and magnesium sulfate. glycemia secondary to beta-blockade should be anticipated and
managed as necessary. The treatment of LQTS is summarized
in Table 2.12.
In pregnancy
Over 900 cases of LQTS have been described in the literature,
Anesthetic management of the
but there are relatively few reports of LQTS in preg-
parturient with LQTS
nancy.64,74,75,76,77,78,79,80,81,82 One study has shown that women
with LQT1 caused by the common KCNQ1-A341 V mutation Booker has reviewed the principles of anesthetic management of
the patient with LQTS (Table 2.13).65 It is important to reduce
are at low risk for cardiac events during pregnancy especially
if beta-blocker therapy is used.79 Cesarean section was more emotional stress and anxiety because high levels of circulating
likely if the neonate was a carrier of the same mutation.79 catecholamines can precipitate dysrhythmias in patients with



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Table 2.13 LQTS in pregnancy: anesthetic considerations

ASSESSMENT
1. Establish whether congenital or acquired long 1. Continue (or establish) appropriate treatment.
QT syndrome (LQTS)
2. Assess status: 2. Avoid triggering cardiac dysrhythmias & increasing catecholamine (CA) levels:
a. electrolytes a. correct hypokalemia, hypomagnesemia, hypocalcemia
b. temperature b. correct hypothermia
c. blood pressure c. avoid/correct hypotension (left uterine displacement, hydration, vasopressors)
d. pain d. adequate pain relief
e. physical/emotional stress & anxiety e. avoid sudden loud noises, vigorous physical exertion (sudden demands for maximal
performance) in congenital LQTS
f. provide information, reassurance, emotional support
g. deaf signage if needed (Jervell, Lange-Nielson syndrome (JLN))
h. judicious use of anxiolytics.
3. History drugs known to cause QT interval 3. Avoid or use cautiously:
prolongation: a. quinidine, procainamide, disopyramide, flecainamide, encainamide, indocainamide,
a. antidysrhythmics lidocaine, sotalol, prenylamine
b. psychotropic drugs b. phenothiazines, tricyclic antidepressants, lithium
c. anesthetic drugs c. thiopental (minimal QT prolongation), succinylcholine, norepinephrine, ephedrine.
4. History ventricular dysrhythmias þ/ “ 4. Anticipate & be prepared to treat with drugs, defibrillation, overdrive pacing.
bradydysrhythmias

LABOR AND DELIVERY
1. Monitors & special preparation 1. Monitor mother & fetus, continuous monitoring if symptoms or dysrhythmia; defibrillator
on standby: immediately available.
2. Interpretation of fetal cardiotocographic 2. Fetal heart rate (FHR) & pattern may reflect beta-blocker therapy (or other
monitoring antidysrhythmic drug) or possible inherited LQTS abnormality.
Fetal scalp sampling may be required to establish fetal acidosis & diagnose fetal distress.
3. Left uterine displacement 3. Avoid aortocaval compression.
4. Effects of therapy on fetus & newborn 4. Diagnosis of fetal distress from FHR may be difficult, may need fetal scalp sampling.
Treat neonatal bradycardia, hypoglycemia if indicated.

REGIONAL ANESTHESIA
1. Sympathetic nervous system blockade 1. Advantageous (decreases catecholamine (CA) levels); avoid relative parasympathetic
overdrive “ sudden bradycardia (PR prolongation).
2. Hemodynamic stability 2. Avoid precipitous drop in BP, use direct & indirect vasopressors judiciously to avoid
triggering dysrhythmias & consequences of hypotension.
3. Lumbar epidural anesthesia 3. Titrate local anesthetic cautiously. Allows more hemodynamic stability. Avoid epinephrine
with local anesthetic or take precautions.
4. Subarachnoid block 4. Quality/density of block usually better (less pain).
Block level less predictable & less controllable.
May be more hypotension “ treat judiciously.
Treat significant bradycardia immediately with atropine/ephedrine.

GENERAL ANESTHESIA
1. Rapid sequence induction & intubation 1. Minimize CA response; beta-blocker useful (topical/i.v. lidocaine may prolong QT interval).
2. Catecholamine increases 2. Maintain adequate depth of anesthesia; avoid hypoxia, hypercarbia, hypotension.
3. Myocardial sensitization to CA 3. Avoid halothane.
4. Drugs with sympathomimetic properties 4. Avoid or use cautiously ketamine, pancuronium, atropine.
5. Drugs with documented safety in LQTS 5. Thiopental (minimal QT prolongation; clinically insignificant), vecuronium, fentanyl, isoflurane.

CA = catecholamine.


LQTS. Drugs and techniques that minimize catecholamine release by an interpreter skilled in deaf signage. Treat conditions known to
and cardiac sensitization to catecholamines should be selected. For aggravate QT prolongation, (e.g. hypokalemia, hypomagnesemia,
those individuals who are profoundly deaf (JLNS), effective com- hypocalcemia) and avoid drugs like procainamide, quinidine, lido-
munication and reduction of stress and anxiety may be enhanced caine, droperidol, ondansetron, and phenothiazines.



48
Chapter 2


A combined spinal epidural technique has been used for vagi-
Table 2.14 Pacemaker associated complications in pregnancy
nal delivery in a woman with LQTS.81 The intial QTc was > 600 ms
and remained prolonged at 560 ms after 11 months™ therapy with 1. Discomfort at implantation site
atenolol. There were no untoward effects from the neuraxial 2. Ulceration at implantation site
analgesia technique.81 3. Pacemaker failure
In another report, spinal anesthesia normalized the QTc that 4. New signs and symptoms
had been prolonged in women with severe preeclampsia.82 It was a. dizziness (exertion/rest)
postulated that hypertension in pregnancy may be associated b. dyspnea (exertion/rest)
with hypocalcemia that in turn prolongs the QT interval; sympa- c. pulmonary edema
thetic blockade from spinal anesthesia was thought to be respon- d. dysrhythmia
sible for shortening the QTc.82 e. extrasystoles
f. tachycardia

Pacemakers and related devices in pregnancy 5. Intrauterine growth restriction
6. Fetal dysrhythmia
Women with pacemakers have conceived and carried pregnancies
to completion successfully. Also, pacemakers have been implanted
during pregnancy with good maternal and fetal outcomes. Current
Table 2.15 Review of pacemaker function
pacemakers and related devices provide more sophisticated sup-
port of the cardiovascular adaptations imposed by pregnancy than
Assessment Rationale
in the past. For example, rate-responsive pacemakers, pro-
1. Indications Optimize pacemaker
grammed to sense a variety of stimuli (e.g. muscle activity, minute
functioning to meet "
2. Signs/symptoms at time of insertion
ventilation) in addition to atrial and ventricular activity, respond
by raising the HR when increased cardiac output is needed.83 3. Course to date demands antepartum,
4. Type, model, response mode(s) of labor/delivery,
pacemaker (see patient identification postpartum
Pacemakers in pregnancy84,85,86,87,88,89 card if available)
5. Pulse generator: replacement date
A parturient is most likely to present with or require a pacemaker
(5“10 year life span device and
or pacemaker-related device (e.g. an implantable cardiac defibril-
operation mode(s))
lator (ICD)) for definitive or prophylactic treatment of: (1) an intrin-
6. Date pacemaker most recently
sic or surgically-induced second-degree (type II) or third-degree
evaluated
heart block; (2) a symptomatic, hemodynamically significant bra-
dydysrhythmia or tachydysrhythmia (recurrent or unresponsive to
drugs); or (3) a potential life-threatening dysrhythmia. In a pregnant
woman such dysrhythmias or conduction problems are likely seen heart disease, looking for new or recurrent cardiac signs and
in conjunction with an intrinsic cardiac condition (congenital, symptoms (chest pain, confusion, dizziness, shortness of breath,
syncope).83 A thorough assessment of pacemaker type and func-
rheumatic or ischemic heart disease, a preexcitation syndrome,
LQTS) or in association with a cardiac surgical procedure. tion should be performed (see Tables 2.15, 2.16). Depending
Pacemaker therapy is occasionally chosen because of drug refrac- on the pacemaker type (e.g. antitachycardia pacemaker) and pro-
toriness or intolerance to side effects. gramming, special adjustments may be required. Interference
from electrical sources (cautery, transcutaneous electrical nerve
stimulation) or from other stimuli (shivering, excess catechola-
Pacemaker/ICD-associated complications
mines, temperature) may have important consequences (see
in pregnancy
Table 2.17). Consultation with a cardiologist regarding appropri-
The probability of successful completion of pregnancy with a ate programming is beneficial. Generally speaking these patients
pacemaker is favorable. Although uncommon in pregnancy benefit from good analgesia during labor. Epidural analgesia
(approximately 25 reports in the literature since 1962), there decreases catecholamines and allows flexibility if an operative
have been documented problems associated with pacemakers delivery is required.
(see Table 2.14).88 Appropriate recognition and treatment of
these complications is essential to ensure optimal maternal and
Antidysrhythmic drugs
fetal outcomes.89,
Important considerations when using antidysrhythmic drugs in
pregnancy and lactation are:
Anesthetic management of the parturient
 adjustments in drug dosage necessitated by changes in mater-
with pacemaker/ICD
nal physiology
 effect of antidysrhythmic drugs on maternal hemodynamics
These patients require careful evaluation of their general status,
review of cardiac history, specifically reviewing their underlying and placental perfusion



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Table 2.16 Anesthetic assessment: pacemaker function

Component Potential problems Action

Pulse generator pocket Discomfort at implantation site Identify problems with generator pocket
Ulceration at implantation site (implantation site)
May become mobile/loose with external
manipulation
Location:
Pectoralis muscle (sc pocket) Usual location unless myopotential inhibition has Note location of pulse generator
left or right subclavian area been a problem Relocate appropriately if necessary
Abdomen LUQ Not an appropriate location during pregnancy
Pulse generator (PG) Malfunction Review EKG for appropriate sensing, pacing,
capture a
00 00
size/shape (usual ¼ 2 ‚ 5 )
Components
Microchip (contains program) Capture problems Confirm capture by demonstration of a pulse
Sensing problems simultaneously with EKG
Avoid absorption of toxic amounts of LA, which
can lead to loss of capture
Battery (¼ most of unit); runs Battery failure Replace battery if battery is known to be at end of
the microchip Competitive inhibition life or soon due for elective replacement
(electromagnetic interference) Avoid or use very cautiously:
Transcutaneous electrical nerve stimulators Magnet in presence of electromagnetic
(TENS) interference
Electrocautery TENS
Peripheral nerve stimulators Electrocautery
Peripheral nerve stimulator
If necessary, chest x-ray b can identify:
Epicardial leads Lead displacement/fracture:
" likelihood with newly-placed or temporary number, position, integrity of pacing leads
leads/trauma Pacemaker ID code
Common sites: Caution re: PAC monitoring with recently
Lead/PG connection inserted pacemaker leads
Insertion into subclavian vein Ensure external pacemaker leads well insulated
Clavicle/1st rib from contact with any source of potential
current leakage
Rate-responsive pacemakers (PM) Competitive sensing/capture Know how PM is programmed re: response
Stimuli sensing options: Fasciculations, shivering, seizures mode(s)
Muscle activity “ responsive Positive pressure ventilation Beware potential problems, make appropriate
MV(TV þ RR) “ responsive CA triggered ˜˜R on T™™ adjustments & verify PM function afterward
Evoke QT“ responsive Body temperature changes Avoid shivering/fasciculations; avoid
Temperature-responsive Hemodynamic changes succinylcholine except RSI; NDMRs
RV dP/dT preferable; RA not contraindicated
Control TV þ RR
(preload/afterload)
Minimize CA discharge
Keep temperature normal
Consult cardiologist re: appropriate
programming

a
Capture may be confirmed by demonstration of a pulse simultaneously with EKG monitoring.
b
Chest x-ray used in pregnant women only when definitely indicated.
sc ¼ subcutaneous; LUQ ¼ left upper quadrant; ID ¼ identification; MV ¼ minute volume; TV ¼ tidal volume;
RR ¼ respiratory rate; RV ¼ right ventricle; CA ¼ catecholamine; RA ¼ regional anesthesia; LA ¼ local anesthetic: NDMR ¼ nondepolarizing muscle
relaxants; PAC ¼ pulmonary artery catheter




50
Chapter 2



Table 2.18 FDA classification of drugs38
Table 2.17 Anesthetic management: parturient with
pacemaker
FDA
PROBLEM MANAGEMENT category Definition

Pain (" CA levels) Provide adequate pain relief A Well conducted human studies have failed to demonstrate
Comfort measures and relaxation techniques any effect on the fetus in any trimester.
TENS; Nitrous oxide/oxygen B No evidence of risk in humans. Animal studies indicate no
Narcotics (IM, i.v., i.v.-PCA) effect with human studies lacking, or animal studies
Regional anesthesia (LEA; SAB) indicate some harm not confirmed in human studies.
General anesthesia C Adequate human studies are lacking, and animal studies
Monitors & special Continuous cardiac monitoring of mother have shown adverse effects. Possibility of adverse
preparation and fetus effects.
Pulse oximetry (SaO2); ABG; FSS prn D Human studies indicate fetal risk. However, the benefits
Alternative or emergency methods of pacing may outweigh risks in pregnant women.
immediately available X Contraindicated in pregnant women. Human or animal
Cardiologist available (PM malfunction; studies indicate substantial fetal risk outweighing the
complications) potential benefits.
Antitachycardia May sense ESU/other intraoperative
FDA ¼ Food and Drug Administration
pacemakers stimulating devices (misinterpret stimuli
as cardiac activity)
Cardiologist consultation/involvement in care
results in SVT conversion, monitoring for recurrence and treat-
Decision re: deactivation antitachycardia
ment with adenosine should follow. The rate can be controlled
function preop
with a longer-acting AV nodal blocking agent (e.g. diltiazem or
beta-blocker). Adenosine also provides a valuable new approach
CA ¼ catecholamine; TENS ¼ transcutaneous nerve stimulation;
to the management of wide-complex tachycardia of uncertain
IM ¼ intramuscular; i.v. ¼ intravenous; i.v.-PCA ¼ intravenous
cause, as it unmasks atrial activity allowing the diagnosis of atrial
patient-controlled analgesia; LEA ¼ lumbar epidural analgesia;
flutter and intra-atrial tachycardia. It has no effect on ventricular
SAB ¼ subarachnoid block; ABG ¼ arterial blood gases; FSS ¼ fetal
tachycardia or preexcited tachycardia.92
scalp sampling; PM ¼ pacemaker; ESU ¼ electrosurgical unit;
Adenosine is safe and effective in pregnancy.94 Its use in preg-
prn ¼ as necessary
nancy was first described in 199195 with several more cases
reported since.29,57,96,97,98 Adenosine crosses the placenta, but
 placental transfer and direct effects on the fetus the rapid onset (<1 min) and short half-life (<10 s) following
intravenous use minimize the potential for fetal effects.99,100
 potential for teratogenicity
 secretion in breast milk. A fetus is more likely to be affected by a maternal dysrhythmia
Experience with the use of some antidysrhythmic drugs in than by adenosine itself, because of its short half-life. Larger
pregnancy, especially the newer ones, is limited. Based on the doses may be required for patients with a significant blood level
evidence available, the FDA has graded antidysrhythmic drugs of theophylline or caffeine. The initial dose should be decreased
according to the relative safety of their use in pregnancy (see to 3 mg in women taking dipyridamole or carbamazepine, those
Table 2.18). The risk of pro-arrhythmia with both class IA and III with transplanted hearts, or if given by central venous access.
antidysrhythmics is the most worrisome side effect for mother. Commonly reported adverse maternal effects include facial flush-
For this reason it is recommended that continuous ECG monitor- ing, headache, sweating, dyspnea, and chest pain. Symptoms asso-
ing be used when therapy with these drugs is initiated, and that ciated with transient asystole may be distressing. Hemodynamically
the need for drug therapy be reassessed on a regular basis.90,91 unstable proarrhythmia requiring electrical cardioversion and pro-
Drugs commonly used to treat dysrhythmias during pregnancy cainamide have been reported after standard doses of adenosine in
the setting of ventricular preexcitation (WPW syndrome).90,91
are summarized in Table 2.19.
If SVT does not convert with adenosine (6 or 12 mg i.v.) rate
control may be achieved using a longer acting AV nodal blocking
Adenosine
agent (e.g. verapamil or diltiazem) or a beta-blocker (Class IIa) as
Adenosine, now commonly used as the initial drug treatment for a second-line agent.
acute narrow-complex tachycardia (PSVT), successfully termi-
nates more than 90% of PSVT.92,93 Adenosine depresses SA node
Verapamil
automaticity and slows AV nodal conduction time and refractori-
ness. It terminates PSVT of the reciprocating type and nodal Verapamil should be given only to patients with narrow-complex
reentrant type (including those associated with accessory bypass reentry SVT, or dysrhythmias known with certainty to be of supra-
tracts). It is an effective alternative to verapamil. If adenosine ventricular origin. Verapamil should not be given to patients with



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Table 2.19 Antidysrhythmic drugs in pregnancy and lactation38

VW FDA
Breastfeeding38
Drug classification classification Indication Adverse effects & cautions

Adenosine V CM Supraventricular Facial flushing, transient No human data
tachycardias dyspnea, chest Probably compatible
discomfort, hypotension,
bronchoconstriction in
asthma
Amiodarone III DM Reentrant dysrhythmias Bradycardia, prolonged QT, Contraindicated
þ
(K channel Refractory VT /VF Torsade de Pointes,
blocker) AF/flutter paresthesia, IUGR,
thyroid disorders in
mother/neonate
Digoxin V CM PSVT, rate control in Caution in WPW Compatible
chronic AF/flutter
Lidocaine Ib BM VT, symptomatic PVD, Drowsiness, agitation, Limited human data
þ
(Na channel prevention of VF paresthesia, cardiac Probably compatible
blocker) depression, bradycardia,
asystole
Procainamide Ia CM SVT, VT, symptomatic PVD, GI symptoms Limited human data
(block fast Prevention of VF, AF in Heart block Probably compatible
sodium WPW (with AV blocking Torsade de Pointes
channel) agent), wide complex Lupus-like syndrome
hemodynamically
stable tachycardias
Esmolol II CM Atrial and ventricular Caution: congestive heart Limited human data
Propranolol (Beta- tachydysrhythmias failure, asthma Probably compatible
blockers) Rate control in chronic Bradycardia: mother/fetus
AF/flutter Hypoglycemia: mother/
fetus
Quinidine Ia CM AF/flutter GI symptoms, Limited human data
Ventricular neonatal Probably compatible
tachydysrhythmias thrombocytopenia,
heart block, Torsade de
Pointes, Lupus-like
syndrome
Verapamil IV CM SVT If wide QRS, Limited human data
Calcium Slow ventricular rate in CONTRAINDICATED Probably compatible
channel AF/flutter until VT ruled out
blockers Heart block,
hypotension, asystole

VW ¼ Vaughan Williams classification of cardiac drugs; FDA ¼ Food and Drug Administration; M ¼ added if rated in manufacturer™s professional
literature; PSVT ¼ paroxysmal supraventricular tachycardia; WPW ¼ Wolff“Parkinson“White syndrome; AF ¼ atrial fibrillation;
SVT ¼ supraventricular tachycardia; VT ¼ ventricular tachycardia; VF ¼ ventricular fibrillation; PVD ¼ premature ventricular depolarization
For additional reading about the impact of drugs on pregnancy and lactation the editors recommend:
Briggs, G. G., Freeman, R. K. & Yaffe, S. J. Drugs in Pregnancy and Lactation, 6th edn., Baltimore: Williams and Wilkins, 2002.
Hale, T. W. Medications and Mothers™ Milk, 10th edn., Amarillo, Texas: Pharmasoft Publishing, 2004 (online orders “ www.iBreastfeeding.com).




Diltiazem
impaired ventricular function or heart failure. Verapamil should be
given in a 2.5 to 5 mg i.v. bolus over two minutes. Repeated doses of The dose of diltiazem is 15“20 mg (0.25 mg/kg) i.v. over two
5“10 mg can be given 15 to 30 minutes apart to a total dose of 20 mg minutes; then 20“25 mg (0.35 mg/kg) in 15 min as required. The
or a 5 mg bolus q 15 minutes to a total dose of 30 mg. maintenance infusion dose is 5“15 mg/h, titrated to HR.



52
Chapter 2


Other uncommon cardiac conditions  In addition to the usual causes of cardiac arrest, the following
during pregnancy are more common in pregnancy than in the general popula-
tion: embolic events (thrombotic, amniotic fluid, or air), an
Arrhythmogenic right ventricular overdose of magnesium sulfate, acute coronary syndrome,
cardiomyopathy (ARVC) preeclampsia/eclampsia, and aortic dissection.
Arrhythmogenic right ventricular cardiomyopathy is a disorder
that predominantly affects the right side of the heart and causes
Summary
ventricular dysrhythmias.101,102 In many patients the disease is
In women with heart disease, sustained dysrhythmias can result in
familial and ARVC may account for up to 5% of unexpected sudden

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