~ ~ T r a n s l a t i o n of Case Report~

A Case of Chronic Dissecting Aortic Aneurysm Complicated witk Rupture into the Right Atrium: Diagnosis by Transesophageal Echocardiography Masahiko HARADA, SJSUM, Hironori HIRAI, SJSUM, Tetsuo LEE, Takuya INOUE, Hideyuki SAKAI, Yuko SUGIYAMA, Makoto SUZUKI, SJSUM, and Tetsu YAMAGUCHI, SJSUM

Abstract Although rupture of a dissecting aortic aneurysm into the pericardial sac, pleural cavities, or mediastinum is a

frequently encountered complication of this entity, rupture into a right-sided cardiac chamber is extremely rare. An 80-year-old woman was admitted to this institution because of dyspnea and facial edema. One year before admission, a diagnosis of dissecting aortic aneurysm (Stanford A type) was made based on results of magnetic resonance imaging and transesophageal echocardiography (TEE) ; however, the patient and her family refused surgical therapy. On admission, blood pressure was 120/60 mmHg, and a Levine 3 /6 ~ continuous murmur was audible at the third and fourth intercostal spaces of the right sternal border. Chest x-ray film showed moderate cardiomegaly, congested lung fields, and bilateral pleura1 effusion. A two-dimensional echocardiogram revealed severe aortic root dilatation 80 mm in diameter with the intimal flap. Color flow Doppler imaging demonstrated abnormal flow toward the back space in dilated ascending aorta. Continuous wave Doppler imaging showed the peak velocity of this flow to be 4.8 m/s . This high-velocity flow strongly suggested that the dissecting aortic aneurysm had ruptured into the right-sided cardiac chamber, and shunt flow from the false lumen of the aortic aneurysm into the right atrium was directly visualized by TEE. Our diagnosis, based on these findings, was chronic dissecting aortic aneurysm with communication into the right atrium. In view of the patient's deteriorating clinical condition, cardiac catheterization was not performed before surgery. Surgery revealed an aneurysm of the ascending aorta measuring 90 mm in diameter and multiple fistulas approximately 2 to 3 mm in diameter arising from the false lumen of the aorta into the right atrium at the base of the atrial appendage. The patient underwent successful replacement of the ascending aorta and closure of the aorto-right atrial fistulas. She had an uneventful postoperative course and was discharged 7 weeks after surgery.

J Med Ultrasonics 2002; 29 (Summer) : 63-69.

K e y w o r d s

aorto-right atrial fistula, dissecting aortic aneurysm, transesophageal echocardiography

1. Introduction

Rupture of a dissecting aortic aneurysm into the thoracic cavity or pericardial sac is a common fatal complication, while rupture directly into or fistulous communication into a cardiac chamber is extremely rare. Several cases involving rupture of a dissecting aortic aneurysm into the right atrium 1~ 1~, the right ventricle19~ 21~, the pulmonary artery, or another right- sided cardiac chamber, 2~22~ have been reported. Special care must be taken to distinguish between rupture into the right atrium or the right ventricle and other

ruptures, because these ruptures produce hemodynamics similar to rupture of the sinus of Valsalva aneurysm.

We encountered a case of chronic dissecting aortic aneurysm complicated by rupture into the right atrium that led to heart failure. Transesophageal echocardiography was useful in establishing the diagnosis of the rupture into the right atrium in this patient, and she was saved by emergency surgery as a result. Here we describe this case and discuss other reported cases.

Third Department of Internal Medicine, Toho University School of Medicine, Ohashi Hospital, 2-17-6, Ohashi Meguro-ku, Tokyo 153-8515, Japan Original article is cited in J Med Ultrasonics 1999; 26 (7) ; 847-853.

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2. Case Report

The patient was an 80-year-old woman with a chief complaint of dyspnea and facial edema. She had become hypertensive at the age of about 70 years and was treated with oral therapy. A dissecting aortic aneurysm developed 9 years later. Her family history contained nothing worthy of note.

At the end of October 1994, the patient visited a local hospital after experiencing a sensation of pressure in the chest. A chest roentgenogram revealed an expanded cardiac silhouette, and she was the referred to this institution. MRI performed at time of admission showed an aortic aneurysm 9 c m in maximum diameter in the ascending aorta (Fig. 1), and transesophageal echocardiography conducted

Fig. 1 Magnetic resonance imaging 1 year before admission showing dilated ascending aorta with an intimal flap (arrow).

simultaneously revealed a severely dilated ascending aortic root with an intimal flap. These findings led to a diagnosis of a dissecting aortic aneurysm (Stanford A type). The echo of the intimal flap showed a partial defect directly above the aortic valve, forming a large entry into a false lumen. Color Doppler imaging demonstrated blood flow into the false lumen through this defect. Thrombus formation in the false lumen was insufficient, and a mural thrombus was partially formed. Color Doppler imaging also showed mild aortic regurgitation without cardiac murmur and shunt flow from the false lumen. Because of the large size of the aneurysm, we decided that surgery was necessary and recommended it to the patient. However, the patient and her family refused surgical treatment, and choosed to be treated for hypertension at a local hospital.

Around early December 1995, the patient began to experience facial edema and dyspnea, both of which gradually worsened. The patient then returned to this institution on 25 December 1995 and was admitted with a diagnosis of heart failure.

The patient was 140 cm tall, weighed 44 kg, and had blood pressure of 120/60 mmHg and pulse rate of 90 beats/min, which is within the normal range. Facial edema was present; respiratory rate was 24 beats/min; and moist rale was audible over the entire lung field. A Levine 3/6 ~ continuous murmur was audible with the point of maximum intensity at the third or fourth intercostal spaces of the right sternal border. No hepatic enlargement, ascites, or neurological abnormalities were observed.

2.1 Laboratory findings on admission WBC was 7500/mm~; RBC, 368 • 10 ' /mm3; Hb,

10.2 g /d l ; Plt, 16 • 104/mm3; CRP, 4.2 mg /d l ; TP, 6.7 g/dl ; ALB, 3.3 g/dl ; AST, 42 U/ l ; ALT, 58 U / l ; LDH, z~69/1; BUN, 33 mg/dl ; Cr, 1.5 mg/d l ; T-Cho, 174 mg/dl ; TG, 80 mg/dl ; CPK, 29 U/ l ; and Glu, 90 m g / d l . The qualitative syphilis test results were negative, and blood gas (room air) was pH 7.45; PaCO2, 30 mmHg, PaO2, 70 mmHg, and HCO~, 29 mmol/L.

2.2 Chest roentgenography Compared with the film taken during the first

examination at this institution in October 1994 (Fig. 2, left), the film obtained on admission (Fig. 2, right) showed marked protrusion of the first and second right arches, bilateral pleural effusion, and lung congestion.

2.3 Electrocardiography Sinus tachycardia (105 b e a t s / r a i n ) and left

ventricular hypertrophy were detected. 2.4 Chest CT Marked dilatation of aortic root and bilateral

pleural effusion were detected. 2.5 Transthoracic eehocardiography The left ventricular long-axis view of the two-

dimensional echocardiogram, (Fig. 3), revealed huge aortic root, 80 mm in diameter, and suggestive of intimal flap. No abnormalities were found in left ventrieular regional wall motion or systolic function, and no annuloaortic ectasia was detected. Color Doppler imaging showed mild aortic regurgitation. The apical four chamber view showed large right atrium. In color Doppler imaging, a mosaic signal appeared in the right atrium during systole to diastole. However, no shunt flow from the left-sided cardiac chamber was identifiable.

The aortic root, examined by color Doppler imaging from the right parasternal approach was found an abnormal flow signal toward the back in the dilated ascending aorta (Fig. 4, top). The continuous-wave Doppler showed this abnormal flow to be continuous and unidirectional (Fig. 4, bottom). Because flow

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Fig. 2 Chest roentgenogram on admission (right; Dec. 25, 1995) showing congested lung fields, bilateral pleural effusion and progression of marked cardiomegaly compared with previous film (left; Oct. 29, 1994).

Fig. 3 Two-dimensional echocardiogram from parasternal long-axis view show the dilated ascending aorta (AO) without annulus dilatation. LA indicates left atrium; LV, left ventricle.

velocity was high, with a peak velocity in the systolic phase of 4.8 m / s e c (pressure gradient, 9 2 m m H g ) , shunt flow to the right-sided cardiac chamber (right atr ium or superior vena cava) was suspected.

The patient 's clinical course and transthoracic echocardiographic findings suggested rupture of the dissecting aortic aneurysm into the right-sided cardiac chamber as the cause, and she was placed under artificial respiratory management by intubation to help to produce sedation.

2.6 Transesophageal eehocardiography Transesophageal echocardiography was performed

under artificial respiratory management using a 5- MHz Bi-plane probe. An intimal flap was observed in the marked dilated ascending aorta. This intimal flap had a large defect just above the aortic valve, and a mural thrombus in the false lumen was partially formed (Fig. 5, top). Color Doppler imaging demonstrated blood flow into the false lumen through this defect (Fig. 5, bottom), which was therefore

Fig. 4 Color Doppler imaging from the right parasternal approach shows abnormal flow (arrow) toward the back space in the dilated ascending aorta (top). Continuous-wave Doppler (CW) shows the peak velocity of this flow be 4.8 m/s, corresponding to a peak pressure gradient of 92 mmHg (bottom).

assumed to be a large entry. However these findings were similar to those observed about 1 year before. The ostium of the left coronary artery showed no abnormality and communicated with the true lumen, but the ostium of the right coronary artery was difficult to detect. By careful manipulation of the probe, on the longitudinal view, a defect of several millimeters in diameter at the site of aortic wall near the right atr ium was detected (Fig. 6, top). Color

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Fig. 5 Horizontal transesophageal ech0cardiograms (TEE) of the ascending aorta (AO). Two-dimensional imaging (top) showing an intimal flap with a large defect (arrow) separating the true lumen (TL) from a false lumen (FL). A mural thrombus (arrows) appears in the false lumen. Color-flow imaging (bottom) demonstrates flow across the defect in the both lumens.

Doppler imaging demonstrated a mosaic shunt flow from the false lumen to the right atrium, accompanying an acceleration flow signal (Fig. 6, bottom).

Based on the patient's clinical course and the findings mentioned previously, our diagnosis was chronic dissecting aortic aneurysm complicated by a rupture into the right atrium, which led to heart failure, and surgical treatment was indicated. Because of her advanced age, progressed symptoms of advanced heart failure, and the diagnosis based on transesophageal echocardiography, cardiac catheterization was not performed.

Subemergent surgery was performed in the department of cardiovascular surgery at this institution on 27 December 1995. Median sternotomy revealed an aneurysm formed by marked dilation (90 m m ) of the ascending aortic root, and part of the dilated root had strongly adhered to the superior vena cava and the right atrial appendage. The ascending aorta was resected under aortic cross clamping at a

Fig. 6 Longitudinal transesophageal echocardiograms (TEE) of the ascending aorta (AO). The site of communication (arrow) between the false lumen (FL) and the right atrium (RA) can be seen (top). Color- flow imaging demonstrates the shunt flow with an acceleration flow signal across the communicating site (botton). LA indicates left atrium.

point directly below the connection of the brachiocephalic arterial branches. This resection disclosed an intimal flap spreading from the point directly above the aortic annulus to the connection of the brachiocephalic arterial branches, accompanied by an organized thrombus in part of the large false lumen. The ostium of the left coronary artery showed no abnormality, although the ostium of the right coronary artery was unidentifiable from either the side of the true or the false lumen. Careful observation of the false-lumen side revealed several small fistulas (approximately 2 to 3 m m in diameter) communications to the right atrial appendage (Fig. 7). Closure of these fistula was performed directly f rom the false-lumen side, and the ascending aorta was replaced with a prosthetic graft (Gelseal, 26 m m ) simultaneously. The postoperative clinical course of this patient was favorable. The symptoms improved, and she was discharged on 12 February 1996, her 49th hospital day.

3. Discuss ion

Rupture into a cardiac chamber, on the right side of

66 J Med Ultrasonics Vot.29 Summer (2002)

T h r o m ~

Right atrial appendage Fistulas Fig. 7

Intimal flap

Schematic cross-sectional representation of aortic dissection and fistulas to the right atrium. There were multiple small fistulas from the false lumen (FL) of the aorta into the right atrial appendage. PA indicates pulmonary artery; SVC, superior vena cava; TL, true lumen.

the heart, especially into the right atrium, rarely occurs as a complication of dissecting aortic aneurysm, and the rupture rarely causes immediate death, unlike the case of rupture into the thoracic cavity, pericardial sac, or mediastinum. Rather, rupture into a right-sided cardiac chamber is induced by heart failure, and is therefore considered to be a complication with a greater possibility o f survival when treated surgically 19).

Rupture of a dissecting aortic aneurysm into the right atrium or other right-sided cardiac chamber is generally characterized by sudden onset of heart failure and continuous murmur. Diseases considered in the differential diagnosis should included rupture of the sinus of Valsalva aneurysm into a right-sided cardiac chamber, coronary artery fistula, and rupture of the right coronary arterial pseudoaneurysm into the right atrium 4~'~)19). It is clinically important to identify a rupture of the sinus of Valsalva aneurysm. If the patient has a history of hypertension with severe chest or dorsal pain and the chest roentgenogram shows marked dilation of the ascending aorta, rupture of the dissecting aortic aneurysm should be considered19< An aortic aneurysm is more likely to rupture if the condition has been diagnosed as a chronic dissecting aortic aneurysm in the ascending aorta, especially one accompanied by insufficient thrombus formation in the false lumen. Transthoracic echocardiography can also discriminate between the two conditions. To establish a diagnosis, however, transesophageal echocardiography is more likely to be useful, as was true in the present case.

The following mechanism may explain why a dissecting aortic aneurysm that occurrs in the ascending aortic root readily ruptures into the right atrium. Because of the lack of continuity of the aortic media at the aortic annulus, a false lumen may form in the space between the aorta and right atrium when dissection occurs at this site, that is, in the aorto-atrial

space '3)'5)23). Because of its thinner wall, rupture of a dilated false lumen into the right atrium is natural.

The Table shows the reported cases of dissecting aortic aneurysm complicated by rupture into the right atrium ~) 17). The first report was published by Kuipers et al 1), who described an autopsy case from a study of the prognosis of 26 patients with dissecting aortic aneurysm in 1963. Our search indicates that this case is the 18th case reported and the fourth case reported in Japan. These patients ranged from 30 to 80 years of age, 80 years being the age of the case reported here. Most of the ruptures occurred during the chronic phase, partially, perhaps, because most of the cases of rupture in the acute phase, in which the rupture is usually into the thoracic cavity or pericardial sac, have resulted in the death of the patient. In the present case, the occasion on which the continuous murmur became audible is unknown because, the follow-up had been carried out in another hospital. Rupture into the right atrium is presumed to have occurred around the beginning of December 1995, however, when the patient started to experience facial edema and dyspnea. The exact time of the onset of the dissecting aortic aneurysm is thus unknown. Nonetheless, we think that rupture occurred during the chronic phase, at least 1 year after the onset.

Early studies reported that antemortem diagnosis of rupture into the right atrium was difficult; consequently, diagnosis was usually determined at autopsy. Cardiac catheterization, angiography, and other invasive methods became dominant later. Only after 1985 did echocardiography, MRI, and other noninvasive diagnostic methods become available. The first use of echocardiography was reported in 1986 by Hurley et al 1') , who used two-dimensional echocardiography and pulsed Doppler analysis. In 1990 Vaidiyanathan et al ~4) , using color Doppler imaging, were the first to report detection of shunt flow from the aorta to the right atrium. In the case reported here, transthoracie echocardiography performed at the time of admission revealed a dilated right atrium, and color Doppler imaging showed a mosaic signal in the right atrium. Furthermore, the right parasternal view showed an abnormal flow signal toward the back in the dilated ascending aorta. Based on the diagnosis of dissecting aortic aneurysm made 1 year before and the fast abnormal flow (peak velocity at the systolic phase, 4 .8m / sec) detected by continuous-wave Doppler, we suspected the presence of shunt flow to the right atrium or the superior vena cava, and transesophageal echocardiography was performed. Although it was not clear in the horizontal view, a partial defect appeared at the site of the aortic wall near the right atrium in the longitudinal view. Further, color Doppler imaging revealed shunt flow from the false aortic lumen to the right atrium, accompanying an acceleration flow signal. These

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Table Reported Cases of Dissecting Aortic Aneurysm Complicated With Rupture Into the Right Atrium.

Case Year Age (Sex) Acute or Chronic Diagnosis of Rupture Therapy Outcome Dissecting Aneurysm Into RA

1 1963 59 ( ? ) Chronic Autopsy (--) Died

2 1964 49 (M) Chronic Autopsy ( ) Died

3 1966 63 (M) Chronic Angiography Surgical Survival ( ~ 6 M)

4 1972 32 (M) Chronic Angiography Medical Died

5 1973 54 (M) Chronic Intraoperation Surgical Survival ( ~ 6 M)

6 1982 61 (M) Acute Angiography Surgical Survival (~0. 5 M)

7 1983 51 (M) Acute Angiography Surgical Died

8 1983 43 (F) Chronic Autopsy ( - - ) Died

9 1984 52 (F) Acute Angiography Surgical ( ? )

10 1985 72 (M) Chronic Cardiac catheterization Surgical Died

11 1986 75 (M) Acute Echoeardiography Surgical Survival ( ~ 6 M)

12 1987 60 (F) Chronic Echocardiography Surgical ( ? )

13 1987 67 (M) Acute Intraoperation Surgical Survival ( ~ 9 M)

14 1990 30 (M) Acute Echoeardiography Medical Survival ( ~ 2 Y)

15 1991 48 ( ? ) Chronic MRI, Angiography Surgical Survival (~1 Y)

16 1993 62 (F) Chronic MRI, Angiography Surgical Survival (~3 M)

17 1993 62 (F) Chronic MRI, Echocardiography Surgical Survival ( ? )

18 Present 80 (F) Chronic Echocardiography (TEE) Surgical Survival (~1.5 M) Case

MRI indicates magnetic resonance imaging; TEE, transesophageal echocardiography.

findings led to the diagnosis. While preoperative transesophageal echocardiogram indicated the presence of a fistula, surgery disclosed several small fistulas. Three reasons account for the failure of preoperative transesophageal echocardiography to detect multiple fistulas. First, because of the advanced symptoms of heart failure, sufficient time was not available for a more detailed examination. Second, the fistulas measured approximately 2 to 3 mm in diameter and may have been too small to be resolved by two-dimensional echocardiography. Last, color Doppler imaging projected them as a stream of shunt signals. However, the broad mosaic signals obtained using color Doppler imaging might have reflected the merger of shunt flow from several fistulas, which should have been evaluated as suggestive of the presence of multiple fistulas. A report by Yokote et a117) in 1993 explained that transesophageal echocardiography performed during surgery detected shunt flow from the false lumen of an ascending aortic aneurysm to the right atrium. The present case is probably the first reported case in which a preoperative diagnosis was established by transesophageal echocardiography. The reasons for not performing angiography or other cardiac catheterization to examine this patient included her advanced age, her advanced symptoms of heart failure, and the fact that the diagnosis was established by transesophageal echocardiography.

The outcome of this case illustrated the rule that prognosis is determined by early diagnosis and early

surgical treatment 4~6). Cases reported during the past 10 years, the present case included, have had relatively long survival times as a result of surgical therapy. Basically, surgery should be performed as early as possible once the diagnosis has been established. A patient with a history of dissecting aortic aneurysm in the ascending aorta with insufficient thrombus formation in the false lumen should be considered a candidate for surgical therapy, after taking into consideration the risk of rupture into the right atrium or other surrounding organs. Transesphageal echoeardiography is also useful for evaluating thrombus formation in the false lumen.

4. Conclusion

We encountered one case of chronic dissecting aortic aneurysm complicated by rupture into the right atrium, which led to heart failure. Transesophageal echocardiography proved useful in establishing the diagnosis of rupture into the right atrium.

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