<Brief
History>
A 59-year-old man was admitted due to sudden onset of
dyspnea and chest discomfort for two hours.
The patient had a medical history of
gouty arthritis and hypertension for 20 years that were
controlled on a regular basis with regular medical control. He
denied other systemic diseases or major operation history. He
had suffered from intermittent chest discomfort and
palpitation since his mid thirties. The frequency of
palpitation was about 3 times per month, and the duration was
less than 1 hour and could be shortened by rest. He underwent
several times of 24-hour Holter ambulatory electrocadiography
(ECG), which reported no significant findings. He had been
regularly followed up at the out-patient clinics since 14
years ago. The baseline ECG showed a normal sinus rhythm with
T wave inversion in leads V1-4 (Figure1
). His blood pressure was controlled around
140/90 mmHg with medication. Echocardiography revealed mild
septal hypertrophy without systolic and diastolic dysfunction.
Treadmill test failed to document any cardiac ischemia.
However, intermittent chest discomfort persisted in recent
years without symptoms of heart failure and exercise
intolerance.
The patient worked in a parking lot. He occasionally drank
with his friends. He denied a family history of cardiac
arrhythmia or sudden death or a personal history of recent
traveling or animal contact.
He suffered from sudden onset of palpitation and chest
discomfort after swimming about 50 meters on the day of
admission, which was followed by severe exertional dyspnea.
The symptoms lasted for 2 hours and could not be relieved by
rest. He drove to our emergency room by himself. Physical
examination revealed an acute ill-looking man with an alert
consciousness. The body temperature was 35oC, the heart rate
was 200bpm, the blood pressure was 79/40 mmHg, and the
respiratory rate was 24 per minute. The other physical
examinations were all unremarkable.
ECG showed a wide QRS complex
tachycardia with a ventricular rate of 222 bpm, a QRS interval
of 254ms, and a monomorphic left bundle-branch-block
configuration (Figure
2).Chest roentgenogram revealed cardiomegaly with
enlargement of the right atrium (Figure
3
). A total of 18mg adenosine and
150mg amiodarone were administered intravenously, but the
arrhythmia persisted. Due to the unstable hemodynamic status,
electrical cardioversion of 100J was given which restored
sinus rhythm to a rate of 66bpm. The blood pressure was
stabilized to around 110/70mmHg. Cardiac enzyme was elevated
mildly after the cardioversion. He was then admitted to the
intensive care unit for further treatment
After admission, IV infusion of
amiodarone was continued for 48 hours. No more ventricular
tachycardia was noted and no chest discomfort was complained
after sinus rhythm was restored. Serial ECG follow-up showed
no evolutional change. Echocardiography showed a dilated right
ventricular (RV) chamber, a normal left ventricle (LV) size
with preserved LV systolic function (ejection fraction: 64%)
and mild mitral and tricuspid regurgitation. Both the
treadmill exercise test and the coronary angiography were
normal excepted that the RV angiogram showed an aneurysm near
the RV apex (Figure
4). Programmed electrical stimulation failed to induce
sustained or nonsustained ventricular tachycardia (VT), but
the signal average ECG revealed a positive late potential. Due
to the impression of arrhythmogenic right ventricular
dysplasia (ARVD), magnetic resonance imaging (MRI) was
arranged, which revealed diffuse fatty infiltrations and
dyskinesis of the RV wall (Figure
5
). According to the criteria, ARVD was
diagnosed. Internal cardioverter defibrillator (ICD) was
implanted smoothly, and he was discharged in stable condition.
<Laboratory
Examination>
1. Hemogram
|
WBC |
RBC |
Hb |
Hct |
MCV |
MCH |
MCHC |
Platelet |
|
K/ul |
M/uL |
g/dl |
% |
fL |
Pg |
g/dl |
K/ul |
940731 |
9.11 |
5.38 |
15.8 |
46.5 |
80.4 |
29.3 |
36.4 |
407 |
|
Band |
Seg . |
Eos |
Baso |
Mono |
Lym |
Aty.Lym |
|
% |
% |
% |
% |
% |
% |
% |
940731 |
0 |
58.7 |
1.1 |
0.4 |
4.3 |
35.5 |
0 | 2.
Biochemistry
|
Na |
K |
BUN |
Cr |
Mg |
Ca |
AST |
|
mmol/L |
mmol/L |
mg/dl |
mg/dl |
mg/dl |
IU/L |
U/L |
940731 |
135 |
5.5 (H8) |
14.3 |
1.4 |
0.98 |
|
|
940801 |
131 |
4.4 |
12.7 |
1.1 |
0.9 |
2.03 |
22 |
|
T cho. |
HDL |
LDL |
TG |
UA |
|
mg/dL |
mg/dL |
mg/dL |
mg/dL |
mg/dL |
940801 |
212 |
24 |
150 |
134 |
5.9 |
|
|
CK |
CKMB |
TnI |
Date |
Time (post S/S) |
U/l |
U/l |
Ng/ml |
0731 |
1500 (4hr) |
186 |
21.5 |
1.69 |
0731 |
1900 (8hr) |
245 |
30.8 |
36.6 |
0731 |
2331 (12hr) |
321 |
34.3 |
4.43 |
0801 |
0525 (18hr) |
320 |
29.3 |
|
0801 |
1110 (24hr) |
277 |
29.3 |
|
0801 |
1915 (32hr) |
260 |
24.4 |
2.36 |
0802 |
0100 (38hr) |
220 |
18.2 |
1.65 |
0802 |
1452 (50hr) |
165 |
12.3 |
0.493 | 3. PT/PTT
|
PT |
INR |
PTT |
|
sec |
|
sec |
940731 |
11.2 |
0.97 |
24.1 | 4.
Urinalysis (94/7/31)
Appearance |
Sp. Gr |
pH |
Protein |
Glucose |
Ketones |
Urobil |
Yellowish |
1.01 |
7.0 |
- |
- |
- |
0.1 |
RBC |
WBC |
Epithelial Cells |
O.B. |
Bil. |
Bact |
0-1 |
0-1 |
0-1 |
- |
- |
- |
<Heart MRI>
- Diffuse fatty infiltrations in the
RV lateral wall, more severe in the basal anteior segment
- Dyskinesis of the RV wall with
multiple small out-pouches during systole is noted.
- Diffuse delayed myocardial hyperenhancement in the RV
lateral wall
<Discussion>
ARVD is an inherited disorder characterized by the
progressive fibrofatty replacement of RV myocardium, initially
with typical regional and later global right and some LV
involvement, with relative sparing of the septum. The
replacement of myocardial tissue with fat or fibrous tissue
appears to involve three different mechanisms, including
transdifferentiation of myoblasts into adipoblasts, apoptosis,
and an inflammatory process.
A familial history of ARVD is present in 30% to 50% of
cases. The most common pattern of inheritance is
autosomal-dominant, although an autosomal-recessive pattern
has also been reported. In molecular genetics, several genetic
loci and mutations associated with this disease have been
discovered. Mutations in genes encoding desmoplakin and
plakoglobin suggest that altered integrity at myocyte
cell-cell junctions may promote myocyte degeneration and
death. It occurred with the repair process consisting of
replacement of myocardium by adipose and fibrous tissue.
Mutations in the gene encoding the cardiac ryanodine receptor
suggest that cytoplasmic calcium overloading may explain the
arrhythmic characteristic of ARVD.
Clinically, ARVD manifests by means of a wide spectrum of
presentations, ranging from isolated premature ventricular
beats to sustained VT or ventricular fibrillation (VF) that
leads to sudden death. ARVD account for 3% to 10% of
unexplained sudden cardiac death at the age of less than 65
years.
Diagnosis of ARVD remains a clinical challenge, especially
in the early stages. Echocardiographic or angiographic
examinations provide the function and morphology of RV.
However, it is still difficult to diagnosis in patients with
minimal RV abnormalities. Endomyocardial biopsy is the gold
standard but the sensitivity is low. Samples are usually taken
from septum where ARVD uncommonly involved. MRI is a promising
technique for determination of the anatomy, function, and
tissue character of RV. However, diagnostic sensitivity and
specificity of MRI still need to be defined. Standardized
diagnostic criteria have been proposed by the Task Force of
the Working Group on Myocardial and Pericardial Disease of the
European Society of Cardiology, as well as by the Task Force
on the Scientific Council on Cardiomyopathies of the World
Heart Federation. The diagnostic criteria involve global
and/or regional dysfunction and structural alterations, tissue
characterization of walls, repolarization abnormalities,
depolarization/conduction abnormalities, arrhythmias, and
family history. The diagnosis of ARVD is based upon 2 major
criteria, 1 major plus 2 minor or 4 minor criteria
A wide range of prognoses from a long-term favorable
outcome to adverse events including sudden death and heart
failure has been suggested. There are several predictors of
worse outcome of patients with ARVD: LV involvement, the
presence of RV or LV dysfunction, a history of VT, and a
history of syncope.
The treatments of ARVD include drugs, catheter ablation,
operations and ICD implantation. Management of patients with
ARVD is individualized and depends on the risk of patients.
Patients with low risk are usually treated empirically with
antiarrhythmic drugs, including amiodarone, sotalol,
s-blockers, flecainide, and propafenone, alone or in
combination. In patients with higher risk, antiarrhythmic drug
therapy guided by programmed ventricular stimulation with
serial drug testing may be more reliable. Non-pharmacological
therapy, including catheter ablation, operation, and ICD use,
is reserved for patients with life-threatening VT or VF in
whom drug therapy is ineffective, or is associated with
serious side effects.
ICD is the only effective safeguard against sudden death in
the ARVD patients. In patients with very high risk, especially
in survivors of cardiac arrest or in patients with a history
of ventricular tachycardia with hemo-dynamic compromise, ICD
implantation should be
encouraged. |