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Journal of The Association of Physicians of India ■ Vol. 64 ■ December 2016
Case Reports
Recurrent Ventricular Tachycardia Due to Long QT Syndrome
Rambabu Singh1, Kshitiz Nath, Archana
Abstract
Long QT syndrome (LQTS) is a rare inherited heart condition in which delayed
repolarization of the heart following a heartbeat, increases the risk of episodes
of Torsades de pointes (TdP, a form of irregular heartbeat that originates from
the ventricles). These episodes may lead to palpitations, fainting, and sudden
death due to ventricular fibrillation. Episodes may be provoked by various stimuli,
depending on the subtype of the condition. We are reporting a case of 37 years
old male whom we diagnosed to have long QT syndrome on the basis of clinical
and ECG findings.
Introduction
T
he long QT syndrome (LQTS) is a
primary electrical disease which is
characterized by prolongation of the
disordered ventricular repolarization
of the corrected QT on the surface
ECG. This disease is caused by various
mutations in at least seven genes coding
for cardiac ion channels. There are
seven known types of inherited LQTS.
The most common ones are LQTS 1,
2, and 3. In LQTS 1, emotional stress
or exercise (especially swimming)
can trigger arrhythmias. In LQTS 2,
extreme emotions, such as surprise,
can trigger arrhythmias. In LQTS 3, a
slow heart rate during sleep can trigger
arrhythmias.
Long QT syndromes can be
associated with
The congenital long QT syndrome
(LQTS) is characterized by abnormally
prolonged ventricular repolarization
due to inherited defects in cardiac
sodium and potassium channels, which
predispose the patients to syncope,
seizure like activity, ventricular
arrhythmias, and sudden cardiac death.
We describe one case that fulfilled
the electrocardiographic, historical
diagnostic criteria and epinephrine
stress test suggestive of LQT syndrome.
Case Report
We report a case of 37 years old male
resident of Jhansi, who suffered from
sudden onset unconsciousness for 4-5
minutes.
This episode was not associated
with any abnormal body movements,
frothing from mouth, any urinary or
fecal incontinence, or limb weakness.
Patient came to our hospital on 15 th
June at 3:15 am. Patient also had a
Fig. 2: ECG showing prolonged QT
interval and notched T waves
Fig. 1: ECG showing Torsades de
pointes at presentation
history of 4-5 similar episodes in
past. These episodes, as described by
patient himself, were precipitated on
doing some heavy work. His BP was
100/70 mm Hg, PR -98/min, chest had
bilateral crepitation. He was admitted
for evaluation. On 15 June at 8 am
patient again become unconscious, an
urgent ECG was done which showed
ventricular tachycardia with a rate
around 360/min. (Figure 1).
Urgent DC shock of 150 J was given
and the VT reverted. Patient again
developed VT at 11 am, 11:45 am, 1:30
pm and 3:00 pm; every time he was
reverted by giving DC shock of 150 to
250 J and he was started on injection
Amiodarone 150 mg IV stat over 10 min
and then 360 mg over 6 hours and was
further maintained on oral treatment.
ECG of our patient showed
prolonged QT interval with corrected
QTc of about 500-510 msec and notched
T waves (Figures 2 and 3). Hemogram,
cardiac enzymes, liver profile, renal
profile and electrolytes were normal.
Patient was discharged on
propranolol and was advised for ICD
implantation. On subsequent followup, patient did not undergo ICD
insertion and remained symptom free
for 2 years, but in Sept 2015, he again
developed similar kind of episode
(Figure 4) which was again reverted by
DC shock. Patient was again advised for
ICD implantation and was referred to
higher center.
Fig. 3: ECG showing prolonged QT
interval and notched T waves
Lecturer, Department of Medicine, MLB Medical College, Jhansi, Uttar Pradesh
Received: 31.12.2015; Revised: 15.03.2016; Accepted: 29.03.2016
1
Journal of The Association of Physicians of India ■ Vol. 64 ■ December 2016
Table 1: Schwartz (1993) LQTS diagnostic
criteria
Points
ECG findings*
A. QTc†
≥480 msec1/2
Fig. 4: ECG after 3 months again
showing ventricular tachycardia
(Torsades de pointes)
Discussion
The idiopathic prolongation of the
QT interval and by the occurrence of
life-threatening tachyarrhythmias,
particularly long QT syndrome (LQTS)
is a congenital disease with frequent
familial transmission, characterized
primarily by an association with
emotional or physical stress. 1 Among
untreated symptomatic patients,
lethality is high, with 20% mortality in
the first year after the initial syncope
and approximately 50% within 10
years 2 ; however, the risk of death
varies among different families. This
poor prognosis has been significantly
improved by the use of pharmacological
or surgical antiadrenergic therapy or
both, which has reduced long-term
mortality to <5 %. 2
In its most characteristic presentation,
with obvious QT prolongation and
stress-induced syncope, the diagnosis
of LQTS is quite straightforward for
physicians aware of the disease. In
cases of borderline QT prolongation
and/or absence of symptoms, however,
a correct diagnosis may be more
difficult.
The new diagnostic criteria are
listed in Table 1, with relative points
assigned to various ECG, clinical and
familial findings. The score ranges from
a minimum value of 0 to a maximum
value of 9 points.
The clinical course of the congenital
LQTS is influenced largely by the gene
affected.3 While cardiac events are more
frequent and occur at a younger age
3
460-470 msec1/2
2
450 msec1/2 (in males)
1
B.
Torsade de pointe‡
2
C.
T-wave alternans
1
D. Notched T wave in three leads
1
E.
0.5
Low heart rate for age§
Clinical history
A. Syncope‡
B.
With stress
2
Without stress
1
Congenital deafness
0.5
Family history
A. Family members with definite
LQTS#
B.
1
Unexplained sudden cardiac death 0.5
below age 30 among immediate
family members
LQTS, long QT syndrome.
*Inspite of the absence of medications or
disorders known to affect
in patients with LQT1 and LQT2, they
are potentially more fatal in patients
with genotype LQT3. Patients with
LQT1 and LQT2 genotype typically
benefit from high dose beta-blocker
t h e r a p y . 4 H o we ve r , p a t i e n t s w i t h
LQT3 are at higher risk at lower heart
rates and potentially may benefit from
pacemaker therapy. In addition, they
shorten their QT-interval more with
sodium channel blockers.
Provocative tests using catecholamine
or exercise testing have long been
considered to unmask some forms of
congenital LQTS. Recent preliminary
data by Ackerman et al. have suggested
the usefulness of an epinephrine test to
unveil concealed LQT1 syndrome 5. An
epinephrine provocative test should
only be done by cardiologists, under
enough preparation of intravenous
beta-blockers and direct cardioverter
for unintentionally induced ventricular
fibrillation.
Both experimental and clinical
studies have suggested a differential
response of action potential duration
(APD) and QT interval to sympathetic
stimulation among LQT1, LQT2, and
81
LQT3. 13 Persistent and paradoxical
prolongation of APD and QT
interval at steady state conditions
of catecholamines is reported in
LQT1 syndrome. 6 In LQT2 syndrome,
catecholamines are reported to initially
prolong but then abbreviate APD
and QT interval, probably because
of an initial augmentation of INa-Ca
and a subsequent stimulation of IKs.
In contrast to the LQT1 and LQT2
syndromes, catecholamines are reported
to constantly abbreviate APD and QT
interval as a result of a stimulation of
IKs in the LQT3 syndrome, because
an inward late sodium current (INa)
was augmented in this genotype. The
epinephrine test may be applied not
only for unmasking silent mutation
carriers with LQT1 syndrome but also
for predicting genotypes.
Facilities for genetic analysis are not
easily available. However, in view of
the growing importance of genotype
specific treatment of this potentially
fatal syndrome, one can utilize the ECG
criteria and epinephrine QT stress test
as a reliable indicator of the underlying
genotype and accordingly tailor the
management.
Conclusion
The availability of effective therapy
for this often lethal disease emphasizes
the importance of early and accurate
diagnosis. Unfortunately, there is
often delay in the diagnosis of LQTS,
and patients with syncope are often
misdiagnosed, most commonly as
affected by a seizure disorder.
References
1. Vincent GM, Abildskov JA, Burgess MJ. Q-T interval
syndromes. Prog Cardiovasc Dis 974; 16:523-530.
2. Schwartz PJ. Idiopathic long QT syndrome: progress and
questions. Am Heart J 1985; 2:399-411.
3.
Zareba W, Moss AJ, Schwartz PJ, Vincent GM, Robinson JL,
Priori SG, et al. Influence of genotype on the clinical course
of the long QT-syndrome. International Long QT Syndrome
Regisrty Research Group. N Engl J Med 1998; 339:960-5.
4. Schwartz PJ, Priori SG, Spazzolini C, Moss AJ, Vincent GM,
Napolitano C, et al. Genotype-phenotype correlation in
the long-QT syndrome: gene-specific triggers for lifethreatening arrhythmias. Circulation 2001; 103:89-95.
5.
Ackerman MJ, Khositseth A, Tester DJ, Hejlik JB, Shen WK,
Porter CB. Epinephrine-induced QT interval prolongation:
a gene-specific paradoxical response in congenital long QT
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