A Comparative study on ECG changes among normal and otherwise healthy congenitally deaf children

 

Suma. S1, Hari Prasad. V2, Abeetha. S3, Tejashwini. K4, Renu Sharda5

1Assistant Professor, Dept of Physiology, Saveetha Medical College and Hospital, Chennai, India.

2Associate Professor, Dept of Forensic Medicine, Panimalar Medical College Hospital and Research Institute, Chennai, India.

3Associate Professor, Dept of Physiology, ACS Medical College and Hospital, Chennai, India.

4Manager, Tata Consultancy Services ltd, Banglore, India.

5Senior Resident, Dept of Plastic Surgery, PGIMER, Chandigarh, India.

*Corresponding Author E-mail: msrenu01@gmail.com, dr.hariprasad86@gmail.com, subramanian.or.abee@gmail.com, teja16k@gmail.com, meena.30@hotmail.com,

 

ABSTRACT:

Background: Congenital deafness is usually seen to be associated with number of heart diseases. Screening congenitally deaf children with ECG can give us an insight on unidentified congenitally associated heart disease. Aim and objective: To study the ECG changes in congenitally deaf children and compare with normal children of the same age group. Materials and methods: We conducted a community based cross sectional analytical study with a sample size of 120 subjects out of which 60 were children from deaf school as cases and 60 were children from normal school with normal hearing as controls. Both the groups had 30 males and 30 females. 12 lead ECG was taken, studied and compared among the two groups. Results: Deaf children showed significant ECG changes like long QTc (16.7%), left axis deviation (3.3%), right axis deviation (1.6%), clockwise rotation (8.33%), anticlockwise rotation (5%), QRS complex abnormalities (45%), T wave inversions (45%). Conclusion: Our study was able to pick up numerous changes in ECG of deaf children. Yet the findings are inconclusive. Further genetic and thorough cardiac evaluation is necessary to comprehensively establish the relation between co-occurrence of ECG changes and congenital sensorineural deafness.

 

KEYWORDS: Deaf children, ECG, long QTc, T wave inversions.

 

 


INTRODUCTION:

Deaf-mutism is a devastating disability. For a person with this disability, it is like a non-rewritable storage device, which takes in all the data and functions without the ability to express it back in any form. On World Hearing Day 3rd March, 2017, World Health Organization drew attention to the economic impact of unaddressed hearing loss through the theme; “Action for hearing loss: make sound investment”.

 

Hearing Day is an annual advocacy event held on 3 March, Designated at the First International Conference on Prevention and Rehabilitation of Hearing Impairment in Beijing, China in 2007. The day aims to raise awareness and promote ear and hearing care across the world.

 

Inherited predisposition to syncope episodes and sudden death due to cardiac arrhythmias and arrest is a genetically heterogeneous disorder that can be transmitted as a recessive or dominant trait. Literature search provides information on number of such associated condtions in deaf individuals.There is evidence that deaf children are more threatened than the general population by life threatening heart arrhythmias1.  Jervell Lange Neilson Syndrome Type 2 is a less common cardio-auditory disorder that is also inherited as an autosomal recessive trait and associated with variants of the gene KCNE1.2

 

Both KCNE1 and KCNQ1 are necessary for normal hearing and cardiac ventricular repolarization. KCNQ1 encodes a slowly activating and slowly deactivating delayed-rectifier potassium channel and contributes to a potassium current that terminates the cardiac action potential3. Also these genes have a pivotal role in development of endocochlear potential in the inner ear. Hence the association between deafness and cardiac abnormalities is inevitable. In the absence of a family history of a prolonged QT interval, the cardiac phenotype of a hearing or deaf individual may remain concealed unless a syncopal episode occurs.4 Hence we intend to carry out this study in order to screen the otherwise healthy children with congenital sensorineuronal deafness by taking proper history and 12 lead ECG to find out if there is any associated cardiac abnormality.

 

AIMS AND OBJECTIVES:

To study the ECG changes by taking a 12 lead ECG in congenitally deaf children and compare with normal children of the same age group.

 

MATERIALS AND METHODS:

Study design: Community based cross sectional analytical  study

Sample size: 120

Cases: 60 (males-30 & females-30)

 

Controls: 60 (males-30 & females-30)

Age group: 6-18 years 

Institutional Ethical clearance: Obtained

 

Cases included 60 deaf children from the Government Deaf School for girls and boys deaf school run by a trust. Control group included 60 normal children from a private primary and High school .

 

The details such as purpose of the study, nature of the study, methods used, were explained to the parents/guardians in their own understandable language. Informed written consents were duly signed by the parents/guardians and the authorities of the respective schools of both the study group and the control group. Assent from children above 12 years was obtained. The children were tested in the premises of their respective schools . The time chosen for the data collection was from 11am to 1pm and 3pm to 5pm.

 

Inclusion criteria:

Children of either sex aged between 6-18 years with normal hearing and with hearing loss were included in the study.

 

Exclusion criteria:

Children with history of hypertension, diabetes mellitus, asthma, known cardiovascular disease, conductive deafness and who are  uncooperative.

 

Procedure:

Electrocardiogram (ECG) machine: Cardiart 6108T of BPL healthcare was used. This is a portable 12- lead electrocardiograph with a single channel printing system, capable of processing all ECG leads simultaneously. Subject was made to lie down comfortably on a couch and after relaxing for ten minutes 12 lead ECG was taken and analysed.

 

STATISTICAL ANALYSIS:

The primary data is expressed in percentage and proportions. The quantitative parameter data like heart rate, QT interval and prolonged QT interval which follow normal distribution were analysed using unpaired t test and data which did not follow normal distribution were analysed using Mann Whitney “U” test. Analysis was done using SPSS software version 22..

 

RESULTS:

Among 60 cases 16.7%(n=10) of children showed long QTc (corrected QT interval) >460ms whereas 3.3%(n=2) children with normal hearing have prolonged QTc.

 

Fig:1- Long Qtc in cases and controls

 

AXIS DEVIATION: Left axis deviation is found in 3.3%(n=2) and right axis deviation is found in 1.6%(n=1) of cases whereas none in controls.

 

Rotation: Clockwise rotation is seen in 8.33% (n=5) and anticlockwise rotation in 5%(n=3) of cases and none in controls.

 

QRS Complex Abnormalities:The occurrence of QRS complex abnormalities in cases is 45% (n=27) and in controls is 5% (n=3). The occurrence of rSŔ́ pattern, qS complex, flutter waves in QRS complexes of various leads in cases and controls are as listed below:

 

Table 1: QRS complex abnormalities

QRS complex

Cases(n)

Controls (n)

Males

females

Males

Females

rSŔ́ pattern in V1

2

2

0

1

rSŔ́ pattern in V2

5

1

1

1

rSŔ́ pattern in V1 &V2

7

6

0

0

rSŔ́ pattern in V2 &V3

1

0

0

0

qS complex in V1

0

1

0

0

Flutter wave in V2

0

1

0

0

R wave >25mm in V5

0

1

0

0

T wave inversion occurrence in cases is 45%(n=27) and in controls is 6.7%(n=4). Details are as follows:

 

Table 2: T wave inversion in various leads

T wave inversion

Cases(n)

Controls(n)

Males

females

Males

females

V2

8

3

2

2

V2,V3

1

1

0

0

V3,V4

1

0

0

0

V2,V4

0

4

0

0

V2-V4

3

1

0

0

V4

1

1

0

0

V2- V6

0

1

0

0

V1-V5

1

0

0

0

V2- V5

1

0

0

0

V1-V6

0

1

0

0

 

 

Fig 2: Mean Heart Rate

 

Table 3:-Comparison of  Heart Rate & QTc  between cases and controls:

Parameters

Cases

(mean±SD)

Controls

(mean±SD)

Mann-Whitney “U” TEST

P Value

HR

79.13±18.35

81.5±11.18

1634

0.382

QTC

388.18±64.99

404.97±64.99

1646

0.420

Comparison of HR ( p value-0.382),QT( p value-0.157) & QTc  (p value-0.420)among overall cases and controls is statistically not significant

 

DISCUSSION:

Our study showed 16.7% of occurrence of long QTc   in deaf children. A similar study after screening about 100 congenitally deaf children by doing ECG and calculated QT interval,  found about 20 congenitally deaf children with a long QT interval and these cases were selected for the study of autonomic functions5.  In another study preliminary cardiological examinations  was performed on 162 deaf children. Within this group, 24 children manifested tachycardia while 4 children manifested-bradycardia. A-V block of I degree was found in 3 children. Incomplete right bundle branch block (RBBB) was observed in 44 children while a complete RBBB was noticed in 1 child. QTc interval was prolonged (> 0.44s) in 12 children suffering from congenital form of deafness and in 16 children suffering from all causes of deafness1. This is also in accordance with our study which showed QRS complex abnormalities in 45% of deaf children and 3.3% left axis and 1.6% right axis deviation, 8.33% clockwise and 5% anticlockwise rotation.

 

In another study researchers investigated the prevalence of long QT syndrome in a school for deaf children, by evaluating  ECG in 350 congenitally deaf children with an age range of 6-19 years. The corrected QT interval (QTc) was calculated by Bazett's formula. Eight children with a QTc interval >440ms were further studied by cardiac examination, repeat ECGs (three times), Holter monitoring, echocardiography, and exercise testing. The families were assessed for a history of syncope and deafness and underwent ECG evaluations. Among these eight children only two girls aged 14 and 15 years were diagnosed as having Long QT yndrome according to Schwartz's criteria6. In another  study the deaf-mute subjects were divided into two subgroups according to the length of their QT intervals: group 1 included 5 cases with the long QT interval (>440 msec), and group 2 included 127 subjects with the normal QT interval (< or =440 msec). Group 3 was composed of 96 control subjects. The mean QT, QTc, JT, and JTc intervals in group 1 were significantly longer than those of group 2  and group 37. Consequently they found  that deaf-mute children who did not meet the criteria for Jervell and Lange-Nielsen syndrome still had evidence of subtle depolarization abnormalities evidenced by intermediate prolongation of QTc, JTc, and the corresponding measures of dispersion.

 

Few other studies also prove that in LQTS, as in the Brugada syndrome, a mutation in an ion channel gene (in some cases the same gene--SCN5A) is responsible for the development of a large transmural dispersion of repolarization, which serves to provide the arrhythmogenic substrate that can lead to sudden death.8 In one kind of  study, all the cases with suspective symptoms reported since 1957 and their proposed prevalence were reviewed. The authors describe the 4 cases they have studied, all of which presented as congenital sensorineural hearing loss and electrocardiographic changes characteristic of Jervell Lange Neilson Syndrome . The relatively high number of cases they have encountered casts doubt on literature that states that the syndrome occurs more frequently in Northern-European populations. Hence, it is advisable to perform an electrocardiogram in all children affected by congenital deafness9.

Another study attempted to identify patients with LQTS among 127 children (age 1.2 to 10 years) with congenital hearing loss.. Although these children did not meet the definite criteria according to Schwartz parameters, all the 10 children could be defined as having intermediate probability of LQTS according to revised criteria10.

 

The results suggest that assessment of ventricular depolarization and repolarization parameters in children with CHL will be helpful in the early detection of JLNS because children with CHL cannot accurately describe the symptoms of syncope.11 In a study eight  of the 19 cochlear implant centers were surveyed and performed electrocardiographic screening. Thirteen cases of long QT syndrome were reported in seven centers, with two related death12.

 

In our study corrected QT interval comparison among overall cases and controls was not significant. In accordance with ours a study compared ECG of 397 deaf children and 361 normally hearing counterparts., the mean QTc was significantly shorter . The mean heart rate was significantly lower in deaf children. The finding goes with our study which also exhibits lower mean heart rate in cases (Table:3 ) compared to controls. Also male cases have lower mean heart rate compared to female cases and female controls have lower heart rate than  male controls.  In the original study when QT and QTc data were recompared after the children were grouped according to the heart rate, the observed difference became less significant or disappeared. In conclusion, there are no major abnormalities for repolarization parameters in children with congenital sensorineural deafness, when compared to hearing counterparts, if heart rates are similar13. The much rarer Jervell-Lange-Nielsen syndrome (with marked QT prolongation and sensorineural deafness) arises when a child inherits mutant KVLQT1 or minK alleles from both parents. Cardiac voltage-dependent sodium channel gene encodes the cardiac sodium channel, and long QT syndrome (LQTS) mutations prolong action potentials by increasing inward plateau sodium current. The other mutations cause a decrease in net repolarizing current by reducing potassium currents through "dominant negative" or "loss of function" mechanisms(14).  Persistent juvenile T-waves inversions are asymmetric, shallow (<3mm) and usually limited to leads V1-3. Inverted T-waves in the right precordial leads (V1-3) are a normal finding in children, representing the dominance of right ventricular forces. T wave inversion in lead III is a normal variant. New T-wave inversion (compared with prior ECGs) is always abnormal. Pathological T wave inversion is usually symmetrical and deep (>3mm) 1. In our study T wave inversion in leads V1-3 represent 21.6% in cases and 6.67% in controls. Examining subjects only with a preliminary screening test with a small sample size remains a limitation of our study   Further  cardiac evaluation is necessary to conclude if the findings are pathological or physiological.

 

CONCLUSION:

The deaf children in our study when screened electrocardiographically showed plenty of changes as depicted above. The findings need to be studied in detail with better diagnostic modalities and further genetic testing is mandatory to prove the real association between ECG changes seen in congenitally deaf children.

 

ACKNOWLEDGEMENT:

We acknowledge contribution by all authors in conducting the study and developing the manuscript and the subjects for being part of the study sincerely.

 

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Received on 29.01.2021            Modified on 24.06.2021

Accepted on 07.09.2021           © RJPT All right reserved

Research J. Pharm.and Tech 2022; 15(4):1594-1597.

DOI: 10.52711/0974-360X.2022.00266