Coarctation of the aorta with some collaterals presenting as aortic dissection detected by 64-MDCT

Summary

Coarctation of the aorta with aortic dissection is sometimes seen in cases of Turner syndrome, and most cases are type A aortic dissection, whereas coarctation of the aorta with type B aortic dissection is unusual. Only two cases of coarctation of the aorta presenting as aortic dissection have been reported in Japan, and only a few cases have been reported worldwide. We report here a case of coarctation of the aorta with some collaterals presenting as aortic dissection (type B) detected by 64-multidetector row computed tomography (MDCT). A 36-year-old man was brought to the emergency room complaining of sudden chest pain and back pain. Since he showed highly developed collaterals, he might never have exhibited symptoms or any limits on movement. Three-dimensional image reconstruction enabled detection of the coarctation of the aorta with some collaterals and aortic dissection in the best projection, and enabled assessment of precise anatomical relationship. In the present case, MDCT gave more useful information than cardiac catheterization for planning the surgical repair of coarctation of the aorta with some collaterals presenting as aortic dissection.

Introduction

Coarctation of the aorta is commonly considered to be a congenital heart disease and is associated with gonadal dysgenesis (Turner syndrome) and bicuspid valve. Coarctation of the aortic arch is usually associated with ductus arteriosus or ligmentum, or tubular hypoplasia of the aortic arch system. Surgical treatment for coarctation of the aorta was first developed and performed in the mid-1940s 1, 2. Cardiac death without surgical repair is usually due to heart failure, coronary artery disease, aortic rupture and/or dissection, aortic valve disease, infective endarteritis or endocarditis, or cerebral hemorrhage 3, 4. Coarctation of the aorta with aortic dissection is also seen in cases of Turner syndrome. Most cases are type A aortic dissection, whereas coarctation of the aorta with type B aortic dissection is unusual. Only two cases of coarctation of the aorta presenting as aortic dissection (type B) have been reported in Japan, and only a few cases have been reported worldwide [5].

Multidetector row computed tomography (MDCT) has recently been recognized as an important resource for the evaluation of known or suspected coronary artery disease, and it can also be used to assess anomalies of the aorta, pulmonary artery, other vascular structures, and cardiac chambers [6]. We report here a case of coarctation of the aorta with some collaterals presenting as aortic dissection (type B) detected by 64-MDCT.

Case report

A 36-year-old man was brought to another emergency room complaining of sudden chest and back pain. Since the incidence of these symptoms was increasing and anuria was seen on the same night, he was brought to our emergency room. During childhood, he had no symptoms of chest and back pain. He had a history of hypertension, but no history of dyslipidemia, diabetes mellitus, or smoking. His blood pressure (BP) in the left or right upper extremity was 120/70 mmHg without any laterality and this was reduced by β-blocker therapy (bisoprolol 5.0 mg/day) to 80/60 mmHg. BP in the left or right lower limbs were 82/65 and 91/66 mmHg, respectively. Both femoral pulses were palpable, but weak and delayed compared to both brachial pulses. His heart rate was 62 beats/min. He had no cardiac murmur. Electrocardiogram did not show left axis deviation or left ventricular hypertrophy. Chest X-ray showed a normal cardiac silhouette and no cardiomegaly (cardiothoracic ratio 44.1%), but some rib notchings were detected. Transthoracic echocardiogram showed normal left ventricular systolic function (left ventricular ejection fraction 63%), and aortic regurgitation with bicuspid valve. It did not show aortic stenosis or ventricular septal defect. Further investigation was performed using 64-MDCT (Aquilion 64, Toshiba, Tokyo, Japan) and a workstation (Zio Station, Zio Soft, Tokyo, Japan) [7]. The volume-rendered image showed coarctation of the aorta with some collaterals presenting as aortic dissection. The collaterals were quite heavy and ran from the left internal mammary artery (Fig. 1A) to the true lumen and left subclavian artery (Fig. 1B) to the false lumen of the descending aorta. The aortic dissection (type B) was from the collaterals of the descending aorta (entry site) to right common iliac artery (distal site) (Fig. 1C–E). Axial and sagittal enhanced CT images revealed similar findings 8, 9. Therefore, the flow in the true and false lumens was completely independent (Fig. 1F and G). The ductus arteriosus was closed. While cardiac catheterization confirmed the MDCT findings, it was difficult to identify the precise location of the drainage site. Coronary angiography showed a collateral from the right coronary artery ostium to the descending aorta (Fig. 1H), in addition to the collaterals detected by MDCT. Focal coronary artery stenosis or obstruction was not seen. In addition, aortic angiography could not give a precise anatomic location. Since the maximum diameter of ascending aorta and descending aorta were 42 mm and 36 mm, respectively, surgical correction will be considered if the dilatations of aorta progress in the near future.

Fig. 1.

Volume-rendered image (A–E) and axial and sagittal enhanced computed tomography images (F and G) as assessed by 64-multidetector row computed tomography, and coronary angiography (G). Ao, aorta; LITA, left internal thoracic artery; LAD, left anterior descending artery; LCX, left circumflex artery; RCA, right coronary artery; True, true lumen; False, false lumen; End, distal end of dissection; Entry, entry site of dissection.

Discussion

Most cases of coarctation of the aorta are diagnosed in infants and in health examinations in elementary or intermediate school [10]. However, some reports have indicated that it can also be diagnosed in older subjects 11, 12. Another study reported that 69% of 35 adult patients with coarctation of the aorta were symptom-free. The symptomatic patients exhibited vertigo, asthenia, palpitation, claudication, and syncope [13]. The present patient had no symptoms during childhood and was diagnosed with hypertension at 19 years of age. Since he showed highly developed collaterals, he might never have exhibited symptoms or any limits on movement. In the reported cases without surgical repair, the patients usually experienced cardiac death due to heart failure, coronary artery disease, aortic rupture/dissection, aortic valve disease, infective endarteritis/endocarditis, or cerebral hemorrhage. The average age at death is about 34 years 3, 4. Therefore, it has been recommended that surgical repair should be performed as soon as possible [14].

If the present patient had been examined by MDCT at age 19 years to identify the cause of childhood-onset hypertension, coarctation of the aorta may have been found at that time. MDCT has been recognized as an important resource for the evaluation of known or suspected heart disease including anomalies [6]. In this case, the presence of coarctation of the aorta could be suspected based on chest X-ray and transthoracic echocardiogram findings, and was diagnosed on MDCT. Three-dimensional image reconstruction enabled detection of the coarctation of the aorta with some collaterals and aortic dissection in the best projection without the need for additional radiation exposure or contrast media, and enabled assessment of the precise anatomical relationship.

In the present case, MDCT gave more useful information than cardiac catheterization for planning the surgical repair of coarctation of the aorta with some collaterals presenting as aortic dissection.