Study Populations:
The study group included 33 β-TM patients (16 girls/17 boys, mean age
18.7±7.7 years) who were transfused every other 3-4 weeks since the
early childhood and on regular chelation program. They all had normal
systolic functions showed by conventional echocardiography measurements;
ejection fraction (EF)>55%, fractional shortening
(FS)>30%. None had thyroid, lung, renal and liver
dysfunctions. Thirty-seven healthy individuals (18 girls/19 boys, mean
age 19.9±8.4 years) were included into the control group.
Serum ferritin measurement: Ferritin ELISA kit (DRG-Germany)
were used for serum ferritin measurements. Serum samples were obtained
from both groups. The samples from the study group were taken before the
transfusion. If there was any signs of infection within one week,
sampling was postponed.
T2*MR imaging: T2*MRI was performed by Siemens Magneton-Avento
1.5 tesla MR device. Measurement was made from septum middle segment on
short axis by using single cross-section dual echo black blood turbo
field echo (TFE) sequences. TFE sequences were taken using
electrocardiogram synchronization during late diastolic phase by
breath-holding technic These sequence parameters were TR (time to
repetition)/TE1 (time echo) /TE2:12/4.6/9.2 milliseconds (msn), flip
angel:30, NEX (number of excitations): 3, FOV (field of view): 350-450,
slice thickness: 10 mm, TFE factors:6. T2* MRI scan was performed only
in the study group within 15-25 minutes and the findings were evaluated
by the same radiologist without knowing TD imaging results. T2* MRI and
TD surveys were performed on same day. The cut-off level for myocardial
overload was accepted as 20 ms.
Echocardiographic evaluation: Conventional echocardiographic
and pulsed-wave Doppler studies were performed using General Electric
Vivid S6 system with 2.5 or 3.5 MHz transducers. Conventional
echocardiographic study included two dimensional, M-mode, pulsed-wave
Doppler measurements. Patients’ measurements were performed by the same
cardiologist without knowing the T2*MRI results within 2 to 5 days
following transfusion and on the same day with T2*MRI. Echocardiographic
examination was done during normal respiration simultaneously with
electrocardiogram tracing in supine or left lateral decubitus position.
All patients had sinus rhythm during examination. M-mode traces were
recorded at the speed of 50 mm/s and the Doppler signals 100 mm/s. Three
consecutive cycles were averaged for every parameter. Left ventricle
(LV) diameters, wall thicknesses, EF were measured from M-mode traces
recorded from the parasternal long-axis view according to the
recommendations of the American Society of
Echocardiography.10 The trans mitral flow velocities
were performed in the apical four-chamber view using pulsed Doppler
echocardiography with the sample volume sited at the tip of the mitral
leaflet. The peak early diastole (E) and late diastole (A) trans mitral
flow velocities, deceleration time (DT) were measured.
For the acquisition of TD velocities; LV images were obtained from the
apical four-chamber view, and a 5 mm pulsed Doppler sample volume was
placed at the level of lateral and septal mitral annuluses. Myocardial
velocities of the lateral tricuspid annulus were similarly obtained by
placing the sample volume at the junction of the tricuspid valve annulus
and the right ventricle free wall. The peak systolic velocity
(Sm), early diastolic myocardial peak velocity
(Em), late diastolic myocardial peak velocity
(Am) and isovolumic contraction (IVC) velocity were
obtained and the results were given as cm/s. The acceleration rate of
isovolumic contraction (IVA) was calculated as the peak IVC velocity
divided by the time interval from baseline to peak (Δt). IVA= IVC/ Δt
(Figure 1). Ejection time (ET), isovolumic relaxation time (IVRT) and
isovolumic contraction time (IVCT) were obtained and the myocardial
performance index (MPI) were calculated by the following formulation;
MPI = (IVRT+IVCT)/ET.
The study group was divided into two subgroups according to T2*MRI
results (patient with cardiac iron overload <20 ms or non-iron
load group ≥ 20 ms). The results obtained from TD imaging were compared
according to these subgroups.
The Uludag University Ethics Committee gave permission for the study.
The written informed consents were also obtained from both patients and
controls.