Abstract Isolated subvalvular pulmonary ste-

nosis is a rare condition and its morphological

evaluation is obscure. Whole heart magnetic

resonance imaging (MRI) is a new, totally non-

invasive technique which allows three-dimen-

sional comprehension of the cardiac structure.

We describe a patient with isolated subvalvular

pulmonary stenosis, in whom whole heart MRI

was useful to detect and evaluate the right

ventricular outflow obstruction.

Keywords Isolated subvalvular pulmonary

stenosis Æ Whole heart magnetic resonance

imaging

Introduction

Isolated subvalvular pulmonary stenosis (subval-

vular pulmonary stenosis without ventricular

septal defect, ISPS) is an uncommon cardiac

abnormality, accounting for 0.09%–2.0% of all

cases of congenital heart disease [1–3] and 10% of

obstructive lesions in the right ventricular outflow

tract [4]. To the best of our knowledge, this is the

first report describing whole heart magnetic res-

onance imaging (MRI) findings in a patient with

ISPS.

Case report

A 57-year-old man was referred to our depart-

ment because of ECG abnormality. He had been

pointed out to have cardiac murmur, which had

been diagnosed as ventricular septal defect when

he was 5 years old, but otherwise, he had been

healthy. On admission, his blood pressure was

126/76 mmHg and the pulse rate was 76/min with

a regular rhythm. Physical examinations on the

chest revealed a harsh, grade 4/6 systolic ejection

murmur, most prominent in the 4th intercostal

space, left ventricular border. Chest X-ray dis-

closed mild cardiomegaly (the cardiothoracic ra-

tio was 54%) and normal pulmonary vascularity.

ECG showed right ventricular hypertrophy. On

echocardiography, there was a systolic jet in the

right ventricular outflow tract proximal to the

pulmonic valve (Fig. 1, left). Continuous wave

Doppler revealed a maximum velocity of 4.0 m/s

which corresponded to the pressure gradient be-

tween the right ventricle and the distal portion of

the right ventricular outflow tract of 64 mmHg

(Fig. 1, right). There was a grade three tricuspid

regurgitation and the peak right ventricular

Y. Sato (&) Æ S. Komatsu Æ S. Matsuo ÆN. Matsumoto Æ S. Yoda Æ S. Tani Æ S. Kunimoto ÆT. Takayama Æ Y. Kasamaki Æ S. SaitoCardiology, Nihon University Hospital, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8309, Japane-mail: yuichis@med.nihon-u.ac.jp

Int J Cardiovasc Imaging (2007) 23:49–52

DOI 10.1007/s10554-006-9124-5

123

CASE REPORT

Isolated subvalvular pulmonary stenosis: depiction at wholeheart magnetic resonance imaging

Yuichi Sato Æ Sei Komatsu Æ Shinro Matsuo ÆNaoya Matsumoto Æ Shunichi Yoda ÆShigemasa Tani Æ Satoshi Kunimoto ÆTadateru Takayama Æ Yuji Kasamaki ÆSatoshi Saito

Received: 10 May 2006 / Accepted: 6 June 2006 / Published online: 29 June 2006� Springer Science+Business Media B.V. 2006

pressure was estimated to be 90 mmHg. There

was no shunt flow from the left ventricle to the

right ventricle. Whole heart MRI was performed

by an Intera Achieva (1.5 T, Philips Medical

Systems, Netherlands) using a free-breathing,

three-dimensional navigator technique [5]. After

the completion of data acquisition for whole heart

MRI, breath-hold cine MRI was performed. Data

acquisition for whole heart MRI required 12 min

and for cine required a additional 5 min. MRI

Volume rendering image from the coronal view

showed the narrowing of the lower part of the

right ventricular outflow tract (Fig. 2a), and the

short axis image showed localized thickening of

the interventricular septum protruding into the

right ventricular outflow tract (Fig. 2b). There

was no pulmonary artery dilatation. Surface vol-

ume rendering images disclosed the normal cor-

onary artery system without significant coronary

artery stenosis (Fig. 2c, d). Cine MRI showed

narrowing of the right ventricular outflow tract

diameter during systole (10 mm, (Fig. 3, left))

and hypertrophic right ventricular free wall at

end-diastole (12 mm, right). There was no flow

Fig. 1 Short-axis view oftwo-dimensionalechocardiographyshowing a jet in the rightventricular outflow tract(left). Continuous waveDoppler echocardiogram(right) showing the flowvelocity of 4.0 m/s,corresponding to thepressure gradient betweenthe right ventricle andright ventricular outflowtract of 64 mm Hg

Fig. 2 Volume renderingimages showingnarrowing of the rightventricular outflow(arrowhead) on thecoronal projection (a) andlocalized thickening of theinterventricular septumprotruding into the rightventricular outflow tract(arrowhead) on the short-axis projection (b).Surface volume renderingimages showing normalleft (c) and right (d)coronary arteries. RV= right ventricle, LV= left ventricle,LAD = left anteriordescending artery, LCx= left circumflex artery,RCA = right coronaryartery

50 Int J Cardiovasc Imaging (2007) 23:49–52

123

void in the right ventricle indicating the presence

of ventricular septal defect. Because of patient’s

refusal of cardiac catheterization and surgical

correction, the patient was discharged with local

follow up.

Discussion

ISPS may occur in a variety of pathological con-

ditions such as double-chambered right ventricle

[6] and hypertrophic cardiomyopathy [7, 8], but

those of primary origin are subvalvular fibro-

muscular obstruction [3] as shown in the present

case. The common presenting symptoms include

exertional dyspnea and syncope, but the correla-

tion between clinical manifestation and severity

of the right ventricular outflow obstruction is not

good [4]. In fact, the present case had been

completely asymptomatic in the presence of right

ventricular pressure overload due to high-pres-

sure gradient (64 mmHg). However, the presence

of high-pressure gradient may cause right ven-

tricular failure and sudden death [8]. Although

echocardiography is the most commonly used

non-invasive modality for diagnosing ISPS, but

the detection rate by echocardiography is limited

to approximately 70% of patients [3]. Cine MRI

may be more accurate for the detection of ISPS

[6, 7], but it suffers the limitation that it only

provides two-dimensional visualization of the

cardiac chambers and great vessels. Recently,

free-breathing, whole heart MRI has enabled

three-dimensional visualization of not only the

cardiac chambers and great vessels but also the

coronary artery system with excellent spatial

resolution [5, 9, 10]. Unlike multidetector-row

computed tomography which also permits three-

dimensional depiction of the cardiac chambers

and coronary arteries [11–13]. MRI is a totally

non-invasive method requiring no radiation

exposure and it is free from contrast medium-re-

lated complications. In contrast to the conven-

tional MRI which requires prospective projection

settings for constructing the multiple cross-sec-

tional images, whole heart MRI provides arbi-

trary cross-sectional images from the previously

acquired three-dimensional data retrospectively.

In addition, whole heart MRI allows evaluation of

the anomalous coronary artery which may

accompany ISPS [14]. However, whole heart MRI

provides images of cardiac chambers and great

vessels only at end-diastole, but not during the

whole cardiac cycle. Thus, frame-by-frame anal-

ysis by cine MRI is essential for the evaluation of

the right ventricular function and development of

subvalvular pulmonary stenosis during systole.

In conclusion, we demonstrated that whole

heart MRI permits three-dimensional depiction

of the cardiac structure and may become a rou-

tine imaging modality for the diagnosis of ISPS.

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Fig. 3 Cine MRI imagesduring systole (left) and atend-diastole (right)showing pronouncednarrowing of the rightventricular outflowdiameter (10 mm, arrows)during systole ascompared to that at enddiastole (19 mm, right).Hypertrophy of the rightventricular free wall(12 mm, black arrow) isalso demonstrated

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