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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 5, September/October 2017

AFRICA

287

suspected significance. Concomitant physical examinations,

including cardiac auscultation were not performed.

The completed studies were uploaded to a cloud-based web

server and stored using a picture archiving and communication

system (PACS) (Studycast; Core Sound Imaging, Inc, Raleigh,

North Carolina) and proprietary software (CoreConnect; Core

Sound Imaging, Inc). The transfer of the echocardiographic

images and data occurred via a secure broadband internet

connection, with CoreWeb validating the integrity and

confidentiality of the transmitted studies using standard secure

(SSL, TLS) encryption.

Post-screening echocardiographic analysis

Two certified professionals initially viewed each echocardiogram.

These included an echocardiographer and a paediatric

cardiologist with level III training in echocardiography (American

Society of Echocardiography), who separately interpreted and

reported on each archived echocardiographic examination using

a standardised format (SmartWorksheets

TM

, CoreWeb, North

Carolina). During this phase of analysis the readers were blinded

to individual demographic data.

The echocardiographic descriptions focused on findings

summarised in the WHF 2012 criteria for RHD and were

categorised as definite RHD, borderline RHD, or no RHD

(Table 1).

10

Physiological (non-pathological) tricuspid valve and

pulmonary valve regurgitation were noted, but not

comprehensively assessed unless there was significant co-existing

aortic and/or mitral valve pathology.

Subjects who were suspected of having echocardiographic

features of RHD or congenital heart disease were then referred

and examined by the Kigali-based paediatric cardiologists (JM,

ER) who are experienced in the diagnosis and management of

RHD, for subsequent management.

Statistical analyses

Data management and statistical analyses of all data were

performed (LM, VN, MS) at the Rwanda Biomedical Centre in

the Medical Research Centre in Kigali using STATA software

(Statacorp LP. College Station, Texas).

Descriptive statistics were performed; data were summarised

using frequency tables and graphs. Confidence interval of RHD

prevalence was computed at the 95% confidence level.

Results

Of the original 3 000 school children randomly selected,

2 693 (89.7%) underwent echocardiographic evaluation. However

on their scheduled day for screening, 307 were not present at

school or were not available. Of these 2 693 subjects, complete

demographic data from 2 501 subjects were available (92.8%; this

is 83.3% of the original 3 000 selected subjects) (Fig. 1).

The age distribution of the 2 501 subjects is shown in Fig.

2. The mean age of these 2 501 subjects who were completely

analysed was 11.2 years.

Of importance, 91% of the subjects undergoing diagnostic

echocardiography were students enrolled in the first six years of

primary school. Approximately 9% of those echocardiographic-

ally evaluated were somewhat older students (ages 16–20 years)

enrolled in the first three years of secondary school. Therefore,

the overall age distribution for the 2 501 subjects was weighted

towards younger school children.

Seventeen of the 2 501 children (0.68%) fulfilled the 2012 WHF

echocardiographic criteria for the diagnosis of RHD, in either the

definite or borderline category (Table 2, modified from reference 10).

Therefore, the RHD prevalence among this sample of 2 501 Rwandan

school children was 6.8/1 000 (95% CI: 4.2/1 000–10.9/1 000).

Characteristics of subjects meeting WHF criteria

for RHD

The age distribution of the 17 subjects with valvular RHD is

shown in Fig. 3. Of the 17 subjects who met the 2012 WHF

criteria, four (23.5%) were identified as definite RHD and 13

(76.5%) subjects were classified as borderline RHD (Fig. 4).

Table 1.World Heart Federation 2012 criteria for echocardiographic

diagnosis of rheumatic heart disease as applied to this study

(modified from reference 10).

Echo criteria for children

20 years of age

Definite RHD (either A, B, C or D):

A) Pathological MR and at least two morphological features of RHD of the MV

B) MS mean gradient

to 4 mmHg (NB – exclude congenital MV anomalies)

C) Pathological AR and at least two morphological features of RHD of the AV

(NB – exclude bicuspid aortic valve and dilated aortic root)

D) Borderline disease of both the aortic and mitral valves as defined below

Borderline RHD (either A, B or C):

A) At least two morphological features of RHD of the MV without pathologi-

cal MR or MS

B) Pathological MR

C) Pathological AR

Normal echocardiographic findings (all A, B and C);

A) MR that does not meet all four Doppler criteria (physiological MR)

B) AR that does not meet all four Doppler criteria (physiological AR)

C) An isolated morphological feature of RHD of the MV or the AV (e.g. valvar

thickening) without any associated pathological stenosis or regurgitation

Echo criteria for adults

>

20 years of age

Definite RHD (either A, B, C or D):

A) Pathological MR and at least two morphological features of RHD of the MV

B) MS mean gradient

to 4 mmHg (NB – exclude congenital MV anomalies)

C) Pathological AR and at least two morphological features of RHD of the

AV in those under 35 years of age only. (Bicuspid AV and dilated aortic root

must first be excluded)

D) Pathological AR and at least two morphological features of RHD of the MV

Pathological regurgitation

Mitral regurgitation (all four Doppler

criteria must be met)

Aortic regurgitation (all four Doppler

criteria must be met)

1. Seen in two views

1. Seen in two views

2. In at least one view jet length

2 cm 2. In at least one view jet length

1 cm

3. Peak velocity

3 m/s

3. Peak velocity

3 m/s

4. Pansystolic jet for at least one

envelope

4. Pandiastolic jet for at least one

envelope

Morphological features of RHD

Mitral valve

Aortic valve

1. AMVL thickening

3 mm

(age-specific)

1. Irregular or focal thickening

2. Chordal thickening

2. Coaptation defect

3. Restricted motion

3. Restricted motion

4. Excessive leaflet tip motion during

systole (hypermobile or flail leaflet)

resulting in abnormal coaptation

4. Prolapse

RHD, rheumatic heart disease; MR, mitral regurgitation; MV, mitral valve;

MS, mitral stenosis; AR, aortic regurgitation; AV, aortic valve; AMVL, anterior

mitral valve leaflet.