Cardiac chanellopathies

 Phase o
 Phase1
 Phase2
 Phase3
 Phase 4

 Brugada syndrome
 Long QT synrome
 Short QT syndrome
 Catecholaminergic polymorphic VT
 Idiopathic ventricular fibrillation
 Short coupled polymorphic VT
 Early repolarisation syndromes

 It was first described in 1992
 Ecg pattern RBBB and persistent ST
elevations in right precordial leads
 Sudden cardiac death
 This is due to imbalance b/w inward and
outward ionic currents at phase 1 defines
pathological substrate for brugada
syndrome.

 This syndrome although rare in the
community have varied presentation
 Ranging from asymptomatic to malignant
ventricular arrythmias like polymorphic VT
,VFl
 Leading to sudden cardiac deathss

 ST segment changes in rt precorial leads in
brugada have three pattrens
 Type 1; coved ST segment with j point
elevation with ST ele >/=0.2 mv followed by
negative T wave
 Type 2 saddle back configuration with high
take off of ST segment >0.2 mv f/b down
sloping of ST elevation ending in positive or
biphasic T wave with out touching base line

 The three types of ST T pattrens may be
transient bio physical factors febrile state
drugs post prandial state post cardioversion
state can unmask type 1 pattern
 Slight prolongation of QTc some times
observed( seen in rt precordial leads )
 SCN5A mutation associated with
depolarisation abnormalities pwave duration
PR and QRS intervals

 Delayed conduction in rt ventricle manifest
as prominent R wave in lead avR resulting in
avR sign R wave >3mmR/Q ratio > .75 in avR
 Af is the most common supraventricular
arrythmia
 Prolonged sinus node recovery time and SA
node conduction time have been reported

 Genetic channelopathy associated with
prolonged ventricular repolarisation
manifest as prolonged QTc in ecg
 Increased propensity to syncope,
polymorphic VT, sudden cardiac death

 Mutations encoding Na and k channels result
in delayed repolarisation
 Slow the inactivation of inward depolarising
sodium or causes retardation of outward K
repolarising currents resulting in increse in
after depolarisation and dispersion of
repolarisation

 Clinical features
 Family history
 Ecg findings
 Quntitative approach to the long QT
syndrome
 Allocating numerical points to these three
factors and divide the possibility of low
,intermediate ,high probability

 QT interval :determined as mean value
derived from 3 to 5 cardiac cycles and is
measured from beginning of earliest onset of
QRS complex to end of T wave
 QT measurement should be in lead2 and v5or
v6
 with the longest value being used

 Bazetts formula for correction of QT interval
is the standard for clinical use some
limitations at particularly slow or fast heart
rates
 QT depression due to labile repolarisation in
patients with long QT
 T wave alternans indicates electrical
instability during repolarisation

 Abnormal T waves ;T wave morphology
corelated to genotype
 LQTS1 infantile ST-T wave broad base T wave
late onset T wave
 LQST2 bifid t wave subtle bifid T wave with
second component on top ofT wave in limb
and left precordial leads or with second
component on downslope of T wave in
inferior and mid precordial leads or low
amplitude merged with U wave

 LQTS3 late onset peaked or biphasic T wave
and asymmetric peaked T waves
 U wave bizzare looking u wavea u wave
alternans
 Sinus node dysfunction sinus brady and sinus
pause in LQTS3
 Respone to epinephrine challenge test in
unmasking of low penetrance KCNQ1
mutations

 Andersen –Tawil syndrome LQTS7
 Multi system involvement periodic paralysis
,dysmorphic features,ventricular arrythmias
 Timothy syndrome highly lethal multisystem
disease with prolonged QT interval ,vent
tachyarrythmias, 2;1 av block ,syndactyly
,dysmorphic facies and immune defeciency
 Mutation in ca channel responsible

 AD channelopathy
 Gain of function mutation
KCNH2,KCNQ1,KCNJ2 k+ channels
 Loss of function CACNA1C, CACNB2B ca
channels
 Abbrevation of ventricular repolarisation
,decreased effective refractory period
increases VF and AF

 Short QT also reported in dilated
cardiomyopathy
 Isolated AF also reported
 Criteria for shortQT
 QTc <330 in males <340 in females even
asymptomatic
 360 in males 370 in females supported by
symptoms or family history

 Response of QT to exercise lack of adaptive
changes in QT interval to heart rate is
 useful in making diagnosis
 Constant QT values and lack of adaptation to
HR with failure to prolong adequately at
slower heart rates and abnormal shortening
during acceleration
 Bazetts formula over corrects the QT at
slower HR

ST T wave changes short or even absent ST
segment with T wave initiating immediately
after s wave asymmetric peaked T waves
due to acceleration of final phase of
repolarisation
Early repolarisation changes duration T wave
peak to T wave end was found to longer
May coexist with brugada syndrome
s

 Genetic disease adrenergic mediated
ventricular arrythmia
 Increase in intracytoplasmic ca+2 due to gain
of function mutation in RyR2 gene or loss of
function in calsequestrin caSQ2leads to
delayed after depolarisation and triggerd
activity
 Poorly responded to beta blockers

 Initiated by ventricular premature beat
closely coupled to preceding sinus beat
 Degenerate into VF episodes are not self
limiting
 Difficult to differentiate from idiopathic
ventricular fibrillation

 charaterised by j point elevation terminal
qrs slurring or notching concave ST segment
elevation and prominent T waves in atleast
two contiguous leads
 Its not benign entity associated with sudden
death and VF
 Due to difference in repolarisation in
different layers of myocardium and different
density of ion channelssss

Cardiac chanellopathies

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