Article, Radiology

Characteristics and diagnostic pitfalls of spontaneous visceral artery dissection in the emergency department

a b s t r a c t

Background: Spontaneous visceral artery dissection (VAD) is a rare disease that mainly occurs in the superior mesenteric artery and Celiac artery. However, VAD has been detected more frequently in the past several years because of the increasing use of computed tomography (CT) for the evaluation of abdominal symptoms. A Prompt diagnosis and referral to a specialist should be made, because VAD occasionally causes critical bowel is- chemia. However, there is no well-established management approach. We performed a retrospective analysis to evaluate the characteristics and prognoses of patients diagnosed with VAD.

Methods: We retrospectively examined data on patients who visited the Emergency Department (ED) at Fukui Prefectural Hospital, and were diagnosed with VAD using enhanced CT scanning from April 2004 to March 2015. All data were collected from the hospital’s electronic medical records. We analyzed the clinical character- istics, comorbidity, risk factors, imaging findings, and treatment of patients.

Results: Fifty-six patients were identified (superior mesenteric artery: 40 patients, celiac artery: 16 patients). The median age of the patients was 54 years (range, 32-86 years) and 89.3% were men. The majority of the patients complained of abdominal pain (37 patients, 66%). Thirty-nine of the patients (69.6%) were hospitalized. All hos- pitalized patients received conservative treatment initially. Three patients received endovascular therapy, and 2 patients received surgery. No fatal cases were observed. Twenty-eight patients presented with ED at their initial visit, and 8 cases (29%) were undiagnosed on their initial visit by emergency physicians, though enhanced CT scans were obtained.

Conclusion: Patients with VAD often present with sudden onset abdominal pain. Most patients were managed successfully with conservative treatment. No fatal cases were observed; however, some cases were missed, even with an enhanced CT scan. It is necessary to include VAD among the differential diagnoses of acute abdom- inal pain. Patients with VAD should be referred to a specialist, because this disease occasionally causes critical Bowel ischemia, necessitating surgical intervention.

(C) 2016

Introduction

Spontaneous isolated visceral artery dissection (VAD) is defined as a dissection of the superior mesenteric artery (SMA), celiac artery (CA), in- ferior mesenteric artery, or renal artery, in the absence of aortic dissection. This disease was once considered to be rare, but has been detected more frequently in the past several years because of the increasing use of com- puted tomography (CT) for the evaluation of abdominal symptoms.

The natural history and appropriate treatment for this disease are uncertain because of its past rarity. The clinical course of this disease

? Source of Support: None.

?? Name of organization and date of assembly: 2015 European Congress on Emergency Medicine (ECEM), 10-14 October 2015.

* Corresponding author at: Emergency Department, Fukui Prefectural Hospital, 2-8-1 Yotsui, Fukui-shi, Fukui, 910-8526, Japan. Tel.: +81 776 54 5151; fax: +81 776 57 2945.

E-mail address: [email protected] (S. Nonami).

may be self-limited. It is potentially life-threatening and may require ur- gent treatment when bowel ischemia or arterial rupture occurs. A vari- ety of treatment options have also been described, including conservative management with or without antithrombotic therapy, endovascular treatment, and open surgery; however, there is no recom- mended management approach.

To address this issue, we investigated the clinical findings, natural history, and outcomes of treatment in patients with isolated spontane- ous visceral artery dissection.

Methods

A retrospective review of the radiology database from April 2004 to March 2015 was performed at Fukui Prefectural Hospital in Japan. In 2014, Fukui Prefectural Hospital had 28,995 ED visits and 4854 of the patients underwent abdominopelvic CT scans. VAD was diagnosed using

http://dx.doi.org/10.1016/j.ajem.2016.02.073

0735-6757/(C) 2016

Fig. 1. Spontaneous isolated dissection of superior mesenteric artery.

enhanced CT scans by the presence of an intramural hematoma and/or in- timal flap in the SMA or CA without aortic dissection (Figs. 1, 2). Patients with concomitant aortic dissection were excluded from the study.

We retrospectively analyzed the clinical characteristics, comorbidi- ties, risk factors, imaging findings, treatments, and early outcomes of the patients. We also compared the imaging findings of the CT scans, in- cluding dissection lengths and the distances from the entry site to the origin of the artery. The SMA dissections were classified into 4 catego- ries according to Sakamoto’s classification: type I represented false lu- mens with both entry and reentry; type II represented “cul-de-sac” shaped false lumens without reentry; type III represented thrombosed false lumens with ulcer-like projections defined as localized blood- filled pouches protruding from the true lumens into the thrombosed false lumens; and type IV represented completely thrombosed false lu- mens without ulcer-like projections (Fig. 3) [1].

Treatments were categorized into 3 types: conservative, endovascular, and surgical. Conservative treatment consisted of bowel rest, blood pres- sure control (with or without anticoagulation or Antiplatelet therapy) in- travenous fluid therapy, and parenteral nutritional support. Endovascular treatment included stenting or coiling. Patients with bowel ischemia and arterial rupture were treated surgically. Treatment and management were at the discretion of the attending physician.

Results

We identified 56 patients with VAD. VAD was found in the SMA of 40 patients (the rest in the CA). There were no dissections in other branches. The characteristic, coexisting medical conditions and symp- toms are summarized in Table 1. Most patients were male (89.3%).

Fig. 2. Spontaneous isolated dissection of celiac artery.

Fig. 3. Sakamoto’s classification of spontaneous isolated dissection of superior mesenteric artery.

The median age of the patients was 54 (range, 32-86). The median follow-up duration was 22.5 months (range, 1-112). Two patients de- veloped SMA dissection during their follow-up period of CA dissection. The most common comorbidities were hypertension and smoking, both being present in 44.6% of patients. The most common symptom was ab- dominal pain (66.1%). Pain was mostly acute and most often felt in the epigastric region.

The characteristics of patients who came to the ED as a First visit are shown in Table 2. Twenty-eight patients came to ED as the first visit. Eight patients were misdiagnosed by the emergency physicians despite enhanced CT scans. Most of these patients were misdiagnosed with ab- dominal pain of gastrointestinal or musculoskeletal origin.

Table 1

The characteristics, coexisting medical conditions and symptoms

SMA

(n = 40)

CA

(n = 16)

Total

(n = 56)

Characteristics

Sex, male

37 (92.5)

13 (81.3)

50 (89.3)

Age (y)?

52.5 (38-86)

55.5

54 (32-86)

(32-70)

Follow-up duration (m)?

22 (1-112)

23 (3-98)

22.5 (1-112)

Coexisting medical conditions

Smoking (current and ex-

16 (40.0)

9 (56.3)

25 (44.6)

smoker)

Smoking female

0

2 (12.5)

2 (3.6)

Hypertension

20 (50.0)

5 (31.3)

25 (44.6)

Diabetes mellitus

5 (12.5)

3 (18.6)

8 (14.3)

Dyslipidemia

5 (12.5)

1 (6.3)

6 (10.7)

Ischemic heart disease

1 (2.5)

0

1 (1.8)

VAD

Symptoms

2 (5.0)

1 (6.3)

3 (5.6)

Abdominal pain

29 (72.5)

8 (50.0)

37 (66.1)

Region

Imaging characteristics are summarized in Table 3. The SMA dissec- tion was classified as follows: type I 10%, type II 17.5%, type III 27.5%, and type IV 45% (according to Sakamoto’s classification). The dissection entry occurred at a mean distance of 16.3 mm from the SMA and

11.4 mm from the CA ostium. The mean length of the dissections was

79.2 mm for the SMA and 35.1 mm for the CA. Three patients had bowel ischemia at diagnosis.

Treatment details are shown in Table 4. Approximately 70% of the patients were hospitalized. Almost all patients were treated with anti- hypertensives. Seven patients were treated with anticoagulation. All hospitalized patients were initially managed conservatively. However, 3 patients received endovascular therapy after admission. Subsequent CT findings included aneurysmal progression in 2 cases and a prolonged progression in one case. Two patients whose initial imaging showed bowel ischemia responded poorly to the initial conservative treatment and subsequently underwent surgery. The characteristics of the patients who received surgical or endovascular therapy are shown in Table 5. There were no fatal cases.

Discussion

Spontaneous isolated VAD was considered a rare disease in the past; however, VAD has been detected more frequently because of the in- creasing use of CT [2]. Risk factors for VAD have not been established. Past reports suggest that patients with VAD are often middle-aged men with a history of hypertension and smoking [3-9]. Cystic medial necrosis, segmental arterial mediolysis, vasculitis, congenital connective

Table 2

The characteristics of patients came to ED as the first visit

SMA (n = 40) CA (n = 16) Total (n = 56)

Epigastric

17 (58.6)

7 (87.5)

24 (64.9)

Characteristics

Umbilical

3 (10.3)

0

3 (8.1)

ED first visit

24 (60.0)

4 (25.0)

28 (50.0)

Left hypochondriac

3 (10.3)

0

3 (8.1)

Symptoms

Hypogastric

1 (3.4)

0

1 (2.7)

Abdominal pain

15 (62.5)

3 (75.0)

18 (64.3)

Unknown

5 (17.2)

1 (12.5)

6 (16.2)

Abdominal and back pain

4 (16.7)

1 (25.0)

5 (17.9)

Onset

Back pain

2 (8.3)

0

2 (7.1)

Acute-sudden

23 (79.3)

6 (75.0)

29 (78.4)

Lower back pain

2 (8.3)

0

2 (7.1)

Back pain

8 (20.0)

3 (18.6)

11 (19.6)

Nausea

1 (4.2)

0

1 (3.6)

Abdominal and back pain

5 (12.5)

1 (6.3)

6 (10.7)

Misdiagnosed in ED

7 (29.2)

1 (25.0)

8 (28.6)

Lower back pain

2 (5.0)

0

2 (3.6)

Gastroenteritis

3 (42.9)

0

3 (37.5)

Nausea

2 (5.0)

0

2 (3.6)

Musculoskeletal pain

3 (42.9)

0

3 (37.5)

Fatigue

1 (2.5)

0

1 (1.8)

Urolithiasis

1 (14.3)

0

1 (12.5)

Absent (incidentally detected)

2 (5.0)

6 (37.5)

8 (14.3)

Unknown

0

1 (100)

1 (12.5)

Data is expressed as n (%), unless otherwise specified.

* Median value with range.

Diagnosed in ED 17 (70.8) 3 (75.0) 20 (71.4)

Data is expressed as n (%), unless otherwise specified.

Table 3

The imaging characteristics

Sakamoto’s classification

SMA

(n = 40)

CA

(n = 16)

Total

(n = 56)

[6,8,10,12]. DiMusto et al conservatively treated 19 patients with CA dis- section initially, and endovascular treatment was required in 3 patients because of persisting symptoms [13]. Although Suzuki et al reported one fatal case among patients treated conservatively, few fatal cases have been reported so far. In our report, all patients initially received

Type I 4 (10)

Type II 7 (17.5)

Type III 11 (27.5)

Type IV 18 (45)

Distance of the entry from ostium (mm)*

16.3 (10.8)

11.4 (8.1)

Length of dissection (mm)?

79.2 (35.4)

35.1 (39.2)

Bowel ischemia

3 (7.5)

0

3 (5.4)

Data is expressed as n (%), unless otherwise specified.

* Mean value with SD.

tissue disorders, fibromuscular dysplasia, arteriosclerosis, and trauma have also been described as Potential causes of VAD [1,4]. In our report, almost all the patients were male, the median age was 54 years, and pa- tients often had a history of hypertension or smoking.

The main symptom of VAD is typically acute-sudden abdominal pain, which mainly presents in the epigastric region. Nausea and vomiting may coexist with abdominal pain. Some patients experienced back pain and low back pain [5,10]. In our report, the most common symptom was acute abdominal pain in the epigastric region.

VAD typically occurs a few centimeters from the ostium, the ma- jority being in the SMA. The proximal segment of the SMA is fixed be- hind the pancreas, whereas the more distal part is relatively mobile and pivots with changes in bowel position, which may transmit a shearing force to the proximal, retropancreatic portion of the SMA. Park et al. analyzed the shearing force by fluid dynamics and report- ed that the shearing force increases on the anterior wall of the prox- imal SMA. In this report, the mean distance of the SMA dissection entry from the ostium was 16.3 mm. In the CA dissections, the mean distance was 11.4 mm. This result is consistent with previous reports. As for the length of dissection, its association with prognosis has been questioned [3].

The SMA dissections were classified into four categories according to Sakamoto’s classification [1]. There are, unfortunately, no reports that morphologic appearance influences the prognosis. Katsura et al report- ed that Sakamoto’s classification is not associated with the prognosis [11]. However, Park et al. reported that morphologic appearance may predict the progression of dissection. The dissection with patent entry and re-entry (Type I) may tend to persist without improvement. The dissection with patent entry, but no re-entry (Type II) and patent true lumen but thrombosed false lumen (Types III, IV) may have a higher chance of improvement [5].

There is no well-established treatment. Yun et al. reported the suc- cessful conservative treatment of SMA dissection in 28 patients [3]. Park et al. also reported successful conservative treatment in 46 patients [5]. However, some studies have reported that endovascular or surgical treatment is required when symptoms persist without improvement or when bowel ischemia gets worse after conservative management

Table 4

Summary of treatment

SMA (n = 40)

CA (n = 16)

Total (n = 56)

Hospitalization

31 (77.5)

8 (50.0)

39 (69.6)

Outpatients

Treatment

9 (22.5)

8 (50.0)

17 (30.4)

blood pressure control

38 (95.0)

16 (100)

54 (96.4)

Anticoagulation

7 (17.5)

0

7 (12.5)

conservative treatment, with endovascular or surgical treatment per- formed later if bowel ischemia or progressing dissection was evident. Two of 3 patients whose initial imaging showed bowel ischemia re- ceived surgical treatment in our report. Patients whose initial imaging showed bowel ischemia may tend to received surgical treatment eventually. There were 2 patients with new occurrence of VAD in other branches during their follow-up period of first VAD. However, No fatal case was observed. Therefore, conservative treatment should be a reasonable initial option in the absence of bowel ischemia or arterial rupture.

Antithrombotic therapy for VAD is controversial. Some reports have advocated antithrombotic therapy to prevent distal emboli or thrombi [14,15]. In contrast, Min et al reported the successful treatment of a SMA dissection without anticoagulation [16]. There is no consensus on antithrombotic therapy. In our report, seven patients received anticoagulation by heparin. There were findings of bowel ischemia on the initial CT scans of four patients, two of whom received surgical treat- ment. No patients were surgically treated if they did not receive antithrombotics, suggesting that more severe patients tended to receive antithrombotics. In our report, the number of patients treated with an antithrombotic was too small for us to evaluate its efficacy. A larger data set is required to evaluate the efficacy of antithrombotic therapy for VAD.

In our report, 28 patients with VAD initially visited the ED. Eight of these patients were misdiagnosed in the ED. As previously noted, patients with VAD often complain of Epigastric pain or low back pain, both being very common symptoms in the ED. Therefore, it is easily misdiagnosed as other, more common diseases, such as gastroenteritis or Musculoskeletal disorders. Furthermore, all the misdiagnosed patients received an abdominopelvic CT scan with contrast enhance- ment, showing VAD. These findings were most likely missed because their differential diagnosis did not include VAD.

Our study included 56 patients, the largest number among previous single-institution studies. Japan had the largest number of CT scanners in the world as of 2011, and an emergency CT scan is available at any time in most hospitals [17]. As VAD becomes widely recognized and the use of CT scanning becomes more widespread, more VAD cases will be diagnosed. There may be a number of overlooked cases of VAD in countries where a CT scan is not easily available. As VAD can occasion- ally be fatal, it is important to include VAD in the differential diagnosis when patients complain of acute Abdominal or back pain.

The limitations of our study are similar to those of other studies. Although our report included a relatively large number of patients from a single institution, it is a retrospective chart review. A large future investigation is necessary to determine the Optimal treatment for and prognosis of patients with VAD. Additionally, patients were included in our report based on CT findings. Therefore, patients who were treated, operated on, or died from VAD without CT scans could not be included in our study.

Conclusion

The data of 56 patients with VAD were analyzed retrospectively. Patients with VAD often present with sudden onset abdominal pain. Misdiagnosis remains commonplace, even with enhanced CT scans. Therefore, it is necessary to include VAD among the differen- tial diagnoses of acute abdominal pain. Once diagnosed, conservative

Antiplatelet

0

0

0

management seems to be a reasonable option for most patients.

Endovascular

2 (5.0)

1 (6.3)

3 (5.4)

However, is imperative to correctly diagnose VAD and refer the

Surgical

2 (5.0)

0

2 (3.6)

patient to a specialist because occasional bowel ischemia and associ-

Data is expressed as n (%), unless otherwise specified.

ated fatality have been reported.

Table 5

The characteristics of the patients who received surgical or endovascular therapy

Age, gender

Location, length

Sakamoto classification

Risk factors

Symptom

Bowel ischemia

Treatment

Case 1

54, F

CA, 14 mm

HTN, smoking

Epigastric pain

No

Coiling, BPC

Case 2

51, M

SMA, 47 mm

III

Epigastric pain

No

Stenting, BPC

Case 3

65, M

SMA, 44 mm

IV

HTN

Epigastric pain

No

Stenting, BPC

Case 4

57, M

SMA, 100 mm

III

Smoking

Epigastric pain

Yes

Operation, BPC, AC

Case 5

58, M

SMA, 105 mm

III

DM

Abdominal pain

Yes

Operation, BPC, AC

F, female; M, male; HTN, hypertension; DM, diabetes mellitus; BPC, blood pressure control; AC, anticoagulation.

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