CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 1, January/February 2013
222
AFRICA
LCA from the non-coronary sinus in three (3%). There was a single
coronary ostium in 18 (16%). Fifty-three (46%) were symptomatic
at presentation. Diagnosis was made by echocardiography in all and
confirmed by TEE (53%), cardiac MRI (37%), catheterisation (19%),
or angio CT (17%). Surgery was performed in 48 (42%) patients,
including unroofing (41), re-implantation (four), CABG (two), and
excision of a prominent sinotubular ridge (one). There were no surgi-
cal deaths but 13% of patients had complications. The mean CICU
stay was two days (range 1–16) and the mean hospital stay was five
days (range 3–20). There were no deaths or significant morbidities
during follow up (mean 33 months). Ten patients reported continued
symptoms, five after surgical repair. Fifty-two patients were physi-
cally active.
Conclusions:
Death or other significant clinical events are rare in
young patients with AOCA. Surgical correction can be performed
with very low risk but symptoms can persist regardless of treatment
strategy.
1216:DIFFUSIONTENSORMAGNETICRESONANCE IMAG-
ING TRACTOGRAPHY DETECTS MYOFIBRE ARCHITEC-
TURE IN DEVELOPING HUMAN FOETAL HEARTS
Prashob Porayette
1
, William Kostis
2
, Guangping Dai
2
, Van Wedeen
2
,
Stephen Sanders
1
, David Sosnovik
2
1
Boston Children’s Hospital, Massachusetts, USA
2
Massachusetts General Hospital, Massachusetts, USA
Background:
The timing and mechanism of development of the
helical myo-architecture of the human heart is largely unknown.
Understanding normal development is essential for detection of altera-
tions in myofibre architecture associated with congenital and acquired
heart disease. Diffusion tensor MRI (DTI) tractography exploits the
preferential diffusion of water along the direction of muscle fibres to
define myofibre structure and orientation non-destructively.
Hypothesis:
We hypothesised that DTI tractography could delineate
myofibre architecture during heart development.
Methods:
Normal human foetal hearts ranging from 10 to 19 weeks’
gestational age (GA), stored in 10% formalin were studied. DTI data
were obtained using a 4.7-Tesla magnet and 24 diffusion-encoding
directions. The primary eigenvectors of the diffusion tensor field
were integrated into streamlines and colour-coded by their helix
angle (HA). Hearts were then sectioned for histology parallel to the
LV free wall and stained with H&E. Fibre orientation (DTI tracto-
gram) by MRI at multiple levels through the LV wall was compared
with the registered histology sections.
Results:
Fibre orientation by DTI correlated well with histology.
At 10 weeks the myocardium resembled an isotropic tissue without
distinct myofibre patterns. However, by 19 weeks of gestation, LV
myo-architecture closely resembled that seen in adult hearts. The
helix angle varied smoothly from a left-handed helix (0° to –90°)
in the subepicardium (epi) to a right-handed helix (0° to 90°) in the
subendocardium (endo). Fibres in the midwall (mid) were circumfer-
ential (
±
0°). The characteristic crossing helical pattern was present
but less well developed at 14 weeks.
Conclusions:
DTI tractography shows that developing human
myocardium is relatively isotropic at the end of embryogenesis (10
weeks), develops microstructural anisotropy by 14 weeks, and essen-
tially resembles adult myocardium by mid-gestation (19 weeks).
1222: RHEUMATIC FEVER: A SOUTH AFRICAN PERSPEC-
TIVE A PILOT STUDY ASSESSING ADHERENCE, NOTIFI-
CATION AND SECONDARY PROPHYLAXIS
Jacques Liebenberg, Phillip Herbst, Anton Doubell
Division of Cardiology, Department of Medicine, Stellenbosch
University, South Africa
Hypothesis
: (1) The notification system for acute rheumatic fever
(ARF) is underutilised and inadequate to establish a central data base
of rheumatic fever patients. (2) Adherence to secondary prophylaxis
is poor. (3) The factors underlying adherence is multifactorial and
can be addressed by the healthcare system.
Methods
: Thirty-four patients with previous ARF (modified Jones
criteria) or established rheumatic heart disease (RHD) (echocardi-
ography) were subjected to semi-structured interviews. Adherence
was gauged against provincial guidelines as a gold standard.
Echocardiograms were assessed for morphological and functional
abnormality. All patient names were cross correlated with provincial
notification data to evaluate the effectiveness of the notification
system.
Results
: The notification system for ARF at TBH is ineffective,
with utilisation figures during the past nine years of only 12.67%.
Adherence figures were found to be inadequate: 33.8% in the high-
risk period (
<
25 years) and 11.06% in the total recommended peri-
od. Patients’ knowledge of their diagnosis, information transfer at the
time of diagnosis and the presence of a reminder system were some
of the strongest predictors of adherence. Xhosa-speaking patients
living far from healthcare facilities had a poor adherence. Lack of
social support, the absence of indoor toilet facilities and long waiting
times for treatment were significant predictors of poor adherence.
Conclusion
: Gross under-reporting of ARF occurs in TBH.
Adherence to secondary prophylaxis is poor. Factors that are modifi-
able by the healthcare system, which predicted adherence included
patients’ knowledge of their condition, information transfer at the
time of diagnosis, patient perception of the need for prophylaxis and
the presence of a reminder system.
1223: PROGNOSTIC VALUE OF SUBMAXIMAL CARDIO-
PULMONARY EXERCISE PARAMETERS FOR CARDIAC
MORBIDITY IN FONTAN PATIENTS
Wei-Hsuan Chang
1
, Chun-An Chen
1,2
, Ssu-Yuan Chen
3
, Hsin-Hui
Chiu
1
, Jou-Kou Wang
1,4
, Yu-CHuan Hua
4
, Chung-I Chang
5
, Ing-Sh
Chiu
5
, Yih-Sharng Chen
5
, Mei-Hwan Wu
1,4
1
Department of Paediatrics, National Taiwan University Hospital,
Taipei, Taiwan
2
Graduate Institute of Clinical Medicine, College of Medicine,
National Taiwan University, Taiwan
3
Department of Physical Medicine and Rehabilitation, National
Taiwan University, Taiwan
4
Cardiac Children’s Foundation, Taiwan
5
Department of Surgery, National Taiwan University Hospital, Taipei,
Taiwan
Background:
Submaximal exercise parameters are associated with
an increased risk of hospitalisation in patients with heart failure, but
the implication in patients with Fontan circulation remains unknown.
Therefore, we investigated the prognostic value of submaximal exer-
cise parameters in Fontan patients, in whom maximal exercise effort
is often limited.
Methods and Results:
Fifty-two patients who had received Fontan
completion at least 12 months earlier underwent cardiopulmonary
exercise tests at our institute. We evaluated two maximal parameters
[peak oxygen consumption (VO
2
) and heart rate reserve (HRR)]
and two submaximal parameters [oxygen uptake efficiency slope
(OUES) and minute ventilation (VE) to carbon dioxide elimina-
tion (VCO
2
) slope]. Peak VO
2
and the OUES were expressed as the
percentage of predicted values. During a median follow up of 22.7
months, 11 patients (21%) exhibited cardiac morbidity, defined as
cardiac-related hospitalisation. Time-dependent receiver operating
characteristic curve analysis demonstrated that submaximal param-
eters were related to two-year cardiac morbidity (area under the curve
for the OUES
=
0.781,
p
=
0.018; for the VE/VCO
2
slope
=
0.714,
p
=
0.04), whereas peak VO
2
and HRR were not. The optimal threshold
value for the percentage of the predicted OUES was 45%, and for the
VE/VCO
2
slope, it was 37%. Furthermore, the OUES conveyed inde-
pendent prognostic information beyond resting oxygen saturation and
a history of heart failure or protein-losing enteropathy.
Conclusion
: Submaximal exercise parameters provided superior
prognostic information to maximal exercise data for predicting cardi-
