Adult Female Patient with Untreated Truncus Arteriosus Type I and Torsion of Small Bowel Gastrointestinal Stromal Tumor: A Rare Case Report

Introduction

Persistent truncus arteriosus (TA) is a rare congenital heart defect with only a single great arterial vessel supporting the systemic, pulmonary, and coronary circulation [1]. TA accounts for only 2% to 4% of all congenital heart diseases. Fewer than 20% of infants with TA could survive the first year of life without intervention [2]. Here, we report the successful management of a case of an adult patient with uncorrected TA who presented with acute abdominal pain due to pedicle torsion of a small bowel gastrointestinal stromal tumor (GIST).

Case Report

A 41-year-old woman presented to our Emergency Department with acute-onset lower abdominal pain for 2 days. The congenital heart disease TA had been diagnosed at birth, and there had been no surgical intervention. Her body mass index was 15.6, height was 160 cm, and weight was 40 kg. She could complete only some light physical activity and had dyspnea on exertion, with New York Heart Association (NYHA) class III. She did not receive oxygen therapy at home or medical treatment. She had no family history of the disease. An abdominal computed tomography scan revealed a 10×9×12 cm mixed-density mass in the pelvic capacity, causing upstream dilatation of the small intestine (Figure 1). Then, she was transferred to surgical intensive care unit (SICU) to prepare for the emergency surgery.

At admission to the SICU, oxygen saturation (SpO2) on room air was 82%, temperature was 37°C, blood pressure was 96/74 mmHg, heart rate was 140 beats per min, and respiratory rate was 26 breaths per min. The blood count showed a secondary polycythemia, with hemoglobin level of 16 g/dL and hematocrit of 50%. The leukocyte count was 17 000 cells/mm3, and C-reactive protein level was 234 mg/L. The arterial blood gas report showed pH of 7.35, PaO2 of 52 mmHg, PaCO2 of 34 mmHg, and lactate level of 2.0 mmol/L. Physical examination revealed cyanosis, hippocratic fingers, and systolic and diastolic heart murmurs. A 12-lead electrocardiograph revealed atrial fibrillation, with rapid ventricular rate, right ventricular hyper-trophy, ST-segment depression, and T-wave inversion in leads I, II, III, aVL, aVF, and V2–V6. Transthoracic echocardiography found a 33-mm ventricular septal defect, hypertrophic right ventricle, and enlarged left atrium. The size of the left ventricle was normal, with an ejection fraction of 51%. The ascending aorta originated mainly from the right ventricle, and the pulmonary artery originated from the beginning of the aorta (type I according to Collett and Edwards classification [3]) with diameter 9 mm. The sizes of the origins of the right and left pulmonary arteries in bifurcation from the main pulmonary artery were 23 mm and 17 mm, respectively. Color Doppler revealed a bidirectional shunt flow signal across the ventricular septum and severe regurgitation of the mitral and tricuspid valves. The right ventricle systolic pressure was estimated at 110 mmHg (Figure 2).

This patient underwent open surgery, with general anesthesia. She was ventilated by the synchronized intermittent mandatory ventilation volume control mode, with fraction of inspired oxygen (FiO2) of 0.5, tidal volume of 350 mL, and positive end expiratory pressure of 6 cmH2O, which resulted in SpO2 between 82% and 85% and end-tidal carbon dioxide (EtCO2) between 33% and 36%. During the surgery, arterial blood pressure varied from 90 to 100 mmHg systolic and 60 to 70 mmHg diastolic, with dopamine 5 mcg/kg/min. Central venous pressure varied between 10 and 14 mmHg. A mass of 10 cm in diameter was seen in the operation, 80 cm from the ligament of Treitz on the anal side, which was complicated with pedicle torsion and hemorrhagic necrosis (Figure 3A). The proximal small intestine was dilated and obstructive due to pedicle torsion. Then, resection of the tumor and intestinal anastomosis was conducted. The surgery lasted 90 min, and estimated blood loss was 500 mL. During this period, the patient received 600 mL crystalloid solution, with a total urine output of 400 mL by furosemide 20 mg. In terms of postoperative pathology, hematoxylin and eosin staining showed spindle-shaped cells (Figure 3B). The mitotic index was <5/50 high-power fields, and the Ki-67 value was 3%. Immunohistochemical staining was positive for CD117 (KIT; Figure 3C), DOG1 (Figure 3D), and weak positive for SDHB but negative for CD34, smooth muscle actin, BRAF, and S100. Molecular pathology of the KIT gene indicated missense mutations in exon 11 at codon 557. No mutations were found in exons 9, 13, and 17. Also, the mutation of the PDGFRA gene at exons 12 and 18 were not detected. Therefore, the diagnosis of a high-risk small bowel GIST was made.

After the operation, the patient was transferred to the SICU and treated with dopamine to maintain a mean blood pressure ≥65 mmHg. Essential analgesia was given to avoid pain-induced sympathetic tone. On postoperative day 1, the patient was extubated, with stable blood pressure, and sequenced with a high-flow nasal cannula at 30 L/min. Bedside echocardiography was used to evaluate cardiac function and monitor hemo-dynamic instability. Due to the elevated central venous pressure, diuretics were administered intermittently to relieve right ventricular preload. The hemoglobin level varied between 13.5 and 15 g/dL after the surgery. Concentrated red blood cells were prepared to increase hemoglobin levels above 10 g/dL, if necessary. With the application of piperacillin/tazobactam, C-reactive protein and procalcitonin levels dropped significantly. In addition, the patient was at high risk of refeeding syndrome. Nutrition therapy was introduced slowly, and electrolytes were monitored closely and replaced as necessary. After routine monitoring of the arterial blood gas report and laboratory test results was conducted, the patient made an uneventful transfer to the general ward on postoperative day 5 and was discharged from the hospital from postoperative day 12.

Discussion

Persistent TA is rare among congenital heart lesions, accounting for approximately 2% to 4% [4]. TA features a single arterial trunk that supplies the systemic circulation, pulmonary arteries, and coronary arteries. Due to this specific anatomy, 80% to 90% of babies do not survive beyond the first year of their life without correction [5,6]. It is very rare to see patients with unrepaired TA have long-time survival. The etiology of TA is still unclear and is hypothesized to be caused by the arrest of cono-truncal aortic septation during embryological development. It is noted that a strong association has been found between common arterial trunk and microdeletions of the 22q11.2 gene [7,8]. TA is classified into 4 types according to the origin of the pulmonary artery, based on Collett and Edwards classification: type I, the main pulmonary artery arises from the posterior wall of the truncus; type II, 2 pulmonary arteries arise separately from the posterior wall of the truncus; type III, 2 pulmonary arteries arise separately from the lateral walls of the truncus; and type IV, 2 pulmonary arteries arise separately from the descending aorta. This patient had TA type I, the most frequent of the 4 types.

A ventricular septal defect is almost always present with TA [9]. Therefore, the leading clinical manifestations are those of Eisenmenger syndrome. The pulmonary vascular resistance with congenital heart disease makes the left-to-right shunt turn into a right-to-left shunt [10]. The reason for untreated infants surviving to adult age is attributed to pulmonary artery hypertension caused by the increasing pulmonary vascular resistance, which prevents overload of pulmonary blood flow and resulting congestive heart failure. Chen et al reported 2 adult patients with TA with mean pulmonary artery pressure of 66 mmHg [5]. In addition, stenosis of pulmonary artery branches allowed survival for patients with TA by decreasing of pulmonary blood flow and providing protection against congestive heart failure [11]. Owing to cardiovascular pathophysiology abnormalities, some points during general anesthesia should be noted. First, factors inducing elevated pulmonary vascular resistance should be avoided, such as hypothermia, hypercarbia, acidosis, and pulmonary arterial hypoxia. Hypotension, which occurred during our patient’s surgery, was corrected by dopamine rather than sympathomimetic drugs (eg, epinephrine and norepinephrine), to maintain systemic vascular resistance. Second, during controlled ventilation, tidal forces and positive end expiratory pressure increase pulmonary vascular resistance in their direct effects upon mean alveolar pressure, which encourages the microvascular closure [12]. For patients with severe Eisenmenger syndrome, a low ventilator setting should be used, by monitoring SpO2 and EtCO2. Third, we adopted strict fluid administration during our patient’s surgery. Central venous pressure varied between 10 and 14 mmHg.

GISTs are mesenchymal neoplasms, accounting for 0.2% to 1.0% of all gastrointestinal tumors [13]. GISTs can arise in any part of gastrointestinal tract, frequently occurring in the stomach (50%–60%) and small intestine (30%–35%) [14]. Small bowel GISTs are often asymptomatic initially. With the growing of the tumor, patients can present with nausea, vomiting, abdominal pain, palpable abdominal mass, and gastrointestinal bleeding [15]. In the present case, the acute abdominal pain was caused by a small bowel volvulus due to GIST, with a diameter of 10 cm. With the increasing diameter of the tumor in the abdominal cavity, a small intestine volvulus can occur as the tumor rotates. Previous reports found that most tumors were relatively large, with a median diameter of 9.5 cm, and were often complicated with necrosis [16]. Surgical resection with the goal of complete resection is considered the main method of treating GISTs. Lymph node dissection is typically unnecessary, because lymph node metastases are rare (prevalence is about 1%) [17]. Pathologically, the diagnosis of GISTs relies on morphology and immunohistochemistry. For the latter, CD117 (KIT) and DOG1 are the 2 most sensitive and specific markers for GISTs [18]. For patients with a high risk of recurrence, imatinib, which has been approved for the therapy of KIT-positive GISTs, can be considered for adjuvant treatment after surgery [15].

There were some limitations in this study. First, computed tomography angiography, which could present the abnormal structure of the heart in more detail, was not performed. Second, a transoesophageal echocardiography probe was not inserted during the surgery for continuous cardiac monitoring. Third, the monitoring of brain oxygen saturation could more accurately assess the balance between oxygen supply and demand.

Conclusions

This is the first case to report the emergency surgery of a patient with uncorrected persistent TA due to torsion of a small bowel GIST. The underlying pathophysiology of persistent TA is complicated, and the detection of a GIST is often with acute symptoms, posing significant challenges to clinical management. A multidisciplinary team with deep understanding of the disease entity was crucial in the present case. By considering the fixed hemodynamic and respiratory physiology, overtreatment and unrealistic goals were avoided. With the quick and detailed preoperative examination and careful postoperative monitoring, our patient was eventually discharged after being hospitalized for 2 weeks.