Babak Kazemi,
M.D., Arash Arya, M.D., Majid Haghjoo, M.D., Mohammad Ali
Sadr-Ameli, M.D.
Department of Pacemaker and
Electrophysiology, Rajaie Cardiovascular Medical Center, Iran
University of Medical Sciences, Mellat Park, Vali-e-Asr Avenue, Tehran,
1996911151 Iran.
Address for
correspondence: Babak Kazemi MD, Department of Pacemaker and
Electrophysiology, Rajaie Cardiovascular Medical Center, Iran
University of Medical Sciences, Mellat Park, Vali-e-Asr Avenue, Tehran,
1996911151 Iran.
E-mail:
bkazemia1966@gmail.com
Abstract
Annular
submitral aneurysms have been rarely reported in Caucasians. They are
typically diagnosed in non-white adults who present with severe mitral
regurgitation, heart failure, systemic embolism, ventricular
arrhythmias, and sudden cardiac death. In this article, we describe the
case of a white woman, presenting with ventricular tachycardia, who had
a large submitral left ventricular aneurysm diagnosed incidentally
during coronary angiography.
Keywords: submitral aneurysm; ventricular tachycardia.
Introduction
In
1962, Abrahams et al. described 12 patients, with an unusual form of
left ventricular aneurysm, which they termed “annular subvalvular left
ventricular aneurysm”.
1
These aneurysms are of two types: subaortic and submitral. Submitral
aneurysm (SMA) is a congenital outpouching of left ventricular (LV)
wall, invariably occurring adjacent to the posterior leaflet of mitral
valve.
2 SMA is typically
diagnosed in young adults who present with severe mitral regurgitation,
heart failure, systemic embolism, ventricular arrhythmias, and sudden
cardiac death. African blacks account for the majority of the SMA cases
reported in world literature, with an estimated incidence of 34 per
10,000 cardiovascular illnesses. About 15 cases of SMA have been
reported from India.
3 Few
cases of SMA have been reported in Caucasians, all accompanied by
significant mitral regurgitation.
4,5,6
Our patient is
a rare case of a large SMA without involvement of the mitral valve
apparatus, in a female who presented with sustained monomorphic
ventricular tachycardia (SMMVT).
Case Report
A
63-year-old female presented to our institution for recent onset of
paroxysmal palpitation and presyncope. At the emergency department
initial evaluation revealed a rapid pulse rate and the 12-lead
electrocardiogram (ECG) showed a wide QRS complex tachycardia, with a
right bundle branch block morphology, compatible with VT (
Figure-1). This arrhythmia was
successfully converted by 200 J external cardioversion. She was
diabetic, with a long history of hypertension and mild hyperlipidemia.
Her medications included atenolol 100 mg/d, amiodarone 200 mg/d,
enalapril 5 mg/bid, and glibenclamide 5 mg/bid. Physical examination
was unremarkable. The 12-lead ECG during sinus rhythm showed sinus
bradycardia, with a long QT interval (QTc=568 msec, probably because of
amiodarone; QTc before starting amiodaron was normal) and diffuse
nonspecific T wave inversion in inferior and all the precordial leads (
Figure-2). Chest radiogram (CXR)
revealed no abnormality. In echocardiography, LV was mildly dilated
(LVEDD=60mm), with mild dysfunction (LVEF=45%), mild isolated septal
hypertrophy and posterior wall thinning (IVS=14.4mm, PW=6mm). There was
no significant valvular lesion, and right heart chambers had normal
dimensions and function. In laboratory evaluation, blood sugar and
creatinine were mildly elevated, there was no electrolyte or acid-base
abnormality, and cardiac specific enzymes were normal.
Figure
1. Twelve-lead surface ECG during ventricular tachycardia with a
right bundle branch blocks pattern.
Figure
2. Twelve-lead surface ECG during sinus rhythm. Note low heart
rate, long QT interval, and diffuse T wave changes.
Her past
medical history was remarkable for her presentation with atypical chest
pain, palpitation, and presyncope, nine years ago. Myocardial perfusion
imaging at that time, revealed a perfusion defect in the anteroseptal
wall, and 24 hr-Holter monitoring showed episodes of nonsustained
ventricular tachycardia. Coronary angiogram showed normal epicardial
coronary arteries. LV angiography was omitted because of relatively
good LV function and no evidence of valvular heart disease at
echocardiographic study. Tilt-test was done for a history of
presyncope. At the active stage, after receiving nitroglycerin spray,
she developed a hemodynamically stable sustained monomorphic
ventricular tachycardia, which was controlled with intravenous
lidocaine. She was recommended oral amiodaron after discharge from
hospital, and had been asymptomatic until several days before her
recent presentation.
According to
her past history and the presenting symptoms, coronary angiography with
left heart catheterization was repeated, which revealed patent
epicardial arteries, with a large posterobasal aneurysm, mild LV
enlargement, no mitral regurgitation, and a global LVEF of about
45% (
Figure-3).
Figure 4. Ventricular angiogram in
the right anterior oblique projection, showing the large posterobasal
aneurysm and mild Left ventricular enlargement. A: the fluoroscopic view; B: the schematic view.
LV
aneurysm in the absence of coronary artery disease is rare,
7 but they may occur in congenital,
traumatic, connective tissue, primary myocardial, or infective heart
disease. Chagas’ disease, infective endocarditis, and idiopathic
or viral myocarditis have caused LV aneurysms of infective origin.
3,8,9
Among LV
aneurysms, the subvalvular types are the least common.
8 Because of the anatomy of the mitral
annulus, congenital aneurysms occur only below the posterior leaflet.
Two-thirds of the mitral annulus is related to the posterior leaflet
which is attached to the myocardium of LV by annular tissue (mitral
ring). The immediate external relationship of the mitral ring is the
epicardium in the atrioventricular groove. A dehiscence of this
muscular-fibrous union will result in a SMA below the posterior leaflet.
8 Morphologically identical aneurysms may
occur in the same position following surgical replacement of the mitral
valve.
8 The remaining
one-third of the mitral annulus is formed by the fibrous union between
the aortic and mitral valves through the so called “mitral-aortic
intervalvular fibrosa”. Perforation of the latter structure has been
described only as a consequence of infective endocarditis.
8 The exact nature or cause of
the defect in subvalvular aneurysms is uncertain. Virtually all the
cases have been described in black people, few in other ethnic groups,
but least in Caucasians.
6
The predilection for constant anatomic sites in the absence of evidence
of coronary atherosclerosis, infection, or trauma would favor a
congenital cause. Subvalvular aneurysms have not hitherto been reported
with another congenital cardiac anomaly. Although their pathogenesis
appears to be similar, it is uncertain, however, whether the dehiscence
between the annulus and the related structure is a primary failure of
union or a later spontaneous separation.
Patients with
SMA usually present with sudden, acute, left-sided heart failure, with
an insidious appearance of cardiac decompensation or with angina. Most
frequently, the lesion is detected incidentally in an otherwise
asymptomatic person. Associated valvular regurgitation is almost
invariably present in these patients.
4
Ventricular tachycardia as the presenting manifestation has also been
reported in patients with SMA.
5,6,10,11,16
In a recent study, the majority of idiopathic LV aneurysms with SMMVT
were restricted to the posterior and/or inferior wall.
12
The diagnosis
of this condition presents few difficulties in cases with anterolateral
aneurysms, in which the combination of an aneurysmal pulsation in the
third intercostal space with a mitral systolic murmur, a chest
radiograph showing an obvious aneurysmal bulge, and an abnormal ECG in
a young black patient is quite typical. Difficulties, as in our case,
do arise when the aneurysm has a posterior origin and does not produce
abnormal pulsation or an aneurysmal bulge in the postero-anterior chest
radiograph.
Considering
the nonspecific, diffuse negative T waves with QT prolongation and the
mild LV dysfunction in our patient, we could not exclude the
possibility of transient myocardial ischemia, due to coronary vasospasm
or recanalized coronary thromboembolism
13.
Although, the former seems unlikely in the absence of cardiac enzyme
elevation, no pathologic Q wave in the ECG, and relatively preserved LV
function. On the other hand, an inflammatory origin also seems
unlikely, considering the patients past history, the morphologic
characteristics of inflammatory aneurysms (small size, sometimes
multiple), and rarity of preserved LV function in this condition (3.3%).
9 The lack of systemic and constitutional
manifestations, no history of trauma, and the normal CXR places other
diagnosis at the most remote possibilities.
An accurate
diagnosis can be made by left ventricular angiography.
4 Although the aneurysm can also be
detected noninvasively by echocardiography, even in expert hands, it
can be missed, especially if it is located in the posterior wall.
4,9 Magnetic resonance
imaging is a promising tool for diagnosing these aneurysms.
14
SMAs may
rupture spontaneously
15 or
be the origin of systemic emboli,
4
and malignant ventricular arrhythmias.
5,6,10,11,16
The definite
treatment is surgical,
3 but
in high surgical risk patients, medical treatment, and implantable
cardioverter-defibrillators in cases with malignant ventricular
arrhythmias, should be considered.
16
Our patient
had clinical characteristics relatively similar to the previously
reported cases, but the occurrence of SMA in a Caucasian woman, with no
mitral valve insufficiency or signs of heart failure and presenting
with a malignant ventricular arrhythmia, is quite unique.
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