AUTHOR CONTRIBUTIONS:
Xihui Liu is charged of drafting article,concept and design; Yonghuai
Wang is charged of interpretation; Shuo Liu is charged of collecting
figures, Guangyuan Li and Lixin Mu are charged of managing of figures;
Jun Yang is charged of approval of article; Chunyan Ma is charged of
critical revision of article.
ABSTRACT : Arrhythmogenic cardiomyopathy (AC) is a rare
inherited myocardial disorder, a cause of sudden death in young people
and atheletes; biventricular involvement is often involved. We report on
a case of AC diagnosed with multimodality imaging, including
transthoracic echocardiography (TTE), two-dimensional strain
echocardiography (2DSE), real-time three-dimensional echocardiography
(RT-3DE) and cardiac magnetic resonance (CMR) imaging. Especially,
combination of 2DSE and RT-3DE was utilized in the diagnosis of AC. In a
word, we review the cardiac anomalies associated with AC by multiple
imaging techniques and highlight the supplementary role of new
echocardiography techniques diagnosing AC when CMR contraindications
exist for AC patients.
KEY WORDS : arrhythmogenic right ventricular dysplasia,
cardiomyopathy, strain, three-dimensional echocardiography
INTRODUCTION :
Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited
cardiomyopathy, which mainly affects the right ventricle
(RV)[1]. The left ventricle (LV) involvement was
considered merely as a late manifestation. Therefore, the disorder is
gradually being mentioned to as arrhythmogenic cardiomyopathy
(AC)[2]. Recently, 3 patterns of AC had been
recognized: the classic subtype, with its acknowledged dominance of
RV; the biventricular variant, recognized by similar involvement of both
ventricles; and left dominant AC[3].
Diagnoses of ARVD are based on revealing RV abnormalities, which include
comprehensive assessment of electrical, anatomical, and functional
abnormalities[4]. Despite it has been suggested
that ARVD with LV involvement might be called AC, there has even no
clear guidelines in the diagnosis of classic subtype of AC. Besides,
diagnosis of minor LV involved AC, classic subtype, has no explicit
criterion yet. We report on a case of a 39-year-old man with classic
subtype AC evaluated by multiple imaging technologies, including
electrocardiogram (ECG), transthoracic echocardiography (TTE),
two-dimensional strain echocardiography (2DSE), real-time
three-dimensional echocardiography (RT-3DE) and cardiac magnetic
resonance (CMR) imaging. Especially, we here introduce the first
application of 2DSE and RT-3DE on the diagnosis of classic AC by
contrasting to CMR.
CASE REPORT :
A 39-year-old male presented with paroxysmal heart palpitations for 7
months and a recurrence in symptoms for 1 week.
Electrocardiogram showed frequent ventricular premature, ventricular
tachycardia (VT) (Fig.1A), complete right bundle branch block (RBBB) and
inverted T wave in leads V1-V6 (Fig.1B).
Echocardiography showed no abnormalities in the standard apical
four-chamber view and parasternal four chamber view (Fig.2A, B), while
bulge and akinesia was observed at the apical segment of the RV lateral
wall on right ventricular-focused view (Fig.3A), and basal segment of
the RV inferior wall on RV inflow tract view (Fig.3B), with respectively
decreased RV longitudinal strain (RVLS, -7.8% ; -16% , Fig.3C, D).
Meanwhile, RV fractional area change (FAC, 31%), tricuspid annular
displacement (TAPSE,16mm) and RV ejection fraction on RT-3DE
(RT-3DE-RVEF, 34%) reduced. Bulge at apex of RV was clearly unfolded on
RT-3DE (Fig.3E).
Although the LV size and systolic function were within normal range on
conventional echocardiography(with LVEF, 60%), with the decreased LV
global longitudinal strain (LV-GLS, -16.4%), especially at apex,
posterior septum and posterior wall of LV (Fig.3F), which was consistent
with the region of cardiac magnetic resonance (CMR-LGE) presentation on
the 4-chamber long axis view (Fig.4). That CMR-LGE demonstrated apex and
lateral wall of RV and posterior septum, posterior lateral wall of LV
myocardial replacement of fatty issues. According to the 2010 ARVC
diagnostic standard[5] and 2017 experts consensus
document of the European Association of Cardiovascular
Imaging[6], this patient was diagnosed with
classic subtype of AC conforming to four main, one minor criteria and LV
involvement. After conducted an implantable cardioverter defibrillator
implantation, the patient got relieved at symptoms.
DISCUSSION :
AC is a relatively rare hereditary cardiomyopathy involving both
ventricles which primary clinical presentations include repeated attacks
of exercise-related ventricular tachycardia, syncope and sudden death.
ECG, TTE and CMR imaging have been well-established diagnostic methods.
And CMR imaging is seen as relatively “golden criterion”. In this
case, typical ventricular arrhythmias (frequent ventricular premature,
ventricular tachycardia, RBBB and T wave inversion in leads V1-V6) were
demonstrated on ECG. Because ventricular tachycardias with a RBBB
morphology can be the first presentation of left dominant or classic
subtype of AC[7]. Hereby, we speculate that both
ventricles of this patient might be involved. TTE was performed and
typical signs of RV dilation, regional wall thinness, and several areas
of wall motion abnormalities in the RV were observed. However, the LV
was neither dilated nor thinned, with an apparently normal diastolic and
systolic function (LVEF, 60%). No evident wall motion abnormality were
observed in the LV. Accordingly, conventional echocardiography is often
unable to detect minor LV involvement discovered on CMR imaging, because
these abnormalities are not regularly related to motion
dysfunction[8, 9].
However, on 2DSE, both the RV and LV regional longitudinal strain were
decreased, which involved areas were consistent with the CMR-LGE
involved regions. Teske AJ, et al reported 2DSE allows the objective
quantification of regional myocardial
function[10], which correlates closely with
CMR-LGE imaging at fibrotic segments in patients with nonischemic heart
disease. What’s more, it can even detect regional abnormalities before
the appearance of CMR-LGE in LV[9],[11].
Despite the capability of 2DSE to detect LV involvement in a large
cohort of patients with ARVD is unknown. 2DSE is a relatively novel
technique able to quantify regional myocardial strain which closely
correlates to CMR-LGE[11].
Besides, RT-3DE provided more precise assessment of RV ejection fraction
(RVEF) and more realistic visual effect of regional wall
dilation[12]. Kim J, et al discovered that in
patients with LV dysfunction, RV volumes and RVEF assessed by RT-3DE
associate well with CMR measurements. RT-3DE may be considered as a more
widely practical and versatile alternate of CMR for evaluating RV size
and function quantificationally in patients with LV
dysfunction[13].