FMT for chronic intestinal obstruction caused by constrictive pericarditis: a case report

A 62-year-old man presented to our department with repeated vomiting, abdominal pain, bloating, and constipation. Echocardiography and computed tomography revealed his thickened pericardium with multiple eggshell-like calcications, and incomplete intestinal obstruction. Colonoscopy showed extensive focal erosions in the colonic mucosa. After fecal microbiota transplantation, the patient's nutritional status was improved, intestinal obstruction was relieved, and his cardiac function his was restored. This case may provide a new option for the treatment of refractory incomplete intestinal obstruction.


Introduction
The human intestinal microbiota is composed of 10 13 to 10 14 microorganisms, which is combined in a certain proportion to maintain the dynamic balance of the microecology. 1 And the intestinal ora is closely related to some physiological activities by producing a large number of metabolites, including endogenous vitamins, short-chain fatty acids (SCFA), and neuroactive substances, etc. 2 However, it can also have undesirable interactions with the host. For example, it appears to be involved in the pathogenesis of diverse diseases such as obesity, diabetes, gastrointestinal diseases, cancer, and cardiovascular (CV) diseases. 3,4 Fecal microbiota transplantation (FMT) is a treatment for diseases by transplanting functional bacteria isolated from the feces of healthy donors into the gastrointestinal tracts of recipient patients, and then remodeling the intestinal ora. In recent years, FMT is mainly used for the treatment of recurrent clostridium di cile infection (CDI), as well as the exploratory researches of various ora-related diseases, like in ammatory bowel disease (IBD), irritable bowel Syndrome (IBS), metabolic syndrome (MS), liver disease, autism spectrum disorder (ASD), autoimmune disease and immunode ciency disease. 5,6,7 Intestinal obstruction is a disease characterized by symptoms of intestinal obstruction are bloating, abdominal pain, vomiting, ceasing exhaust and defecate. Acute intestinal obstruction is often encountered in the emergency department and requires surgical treatment. Although not as urgent as the acute, severe chronic intestinal obstruction can cause serious consequences, such as intestinal necrosis, perforation, and respiratory and heart failure. In the early stages of onset, it can be manifested as incomplete intestinal obstruction. And the incidence of it has increased signi cantly with the gradual aging of society. 8 Studies have found that intestinal obstruction can lead to bacteria overgrowth (BO). 9 At Here, we report a case of a 62-year-old man, with chronic incomplete intestinal obstruction caused by constrictive pericarditis (CP), achieved effective remission after FMT.

Case Report
The patient, 62-year-old, had suffered from repeated abdominal pain, bloating, constipation, leg edema and dyspnea after exercise for 9 months, without receiving effective treatments. And he presented to our department when his symptoms were exacerbated with nausea and vomiting. He had a history of chronic CP. Pericardial knock and hypoactive bowel sounds were discovered upon auscultation. Serological examination showed that B-type natriuretic peptide (BNP), C-reactive protein (CRP), procalcitonin (PCT) and serum albumin (ALB) were 127 pg/ml, 46 mg/L, 0.95 ng/ml and 33.2 g/L, respectively. Therefore, diuresis, improving circulation, nourishing the myocardium, liquid diet, gastrointestinal decompression, enema, catharsis, antibiotics, and other routine treatments for intestinal obstruction were performed for more than one week. There was no remission in his gastrointestinal symptoms, and even tended to worsen. Then, colonoscopy revealed extensive focal erosions in the colonic mucosa ( Fig. 3. A), and histopathology showed acute in ammation in the mucosa ( Fig. 3.C).
The 16S rRNA sequencing analysis of the patient's stool sample revealed the lower diversity and relative abundance of his intestinal ora. Therefore, we decided to try FMT for treatment. With reference to the standardized FMT implementation scheme, the frozen fecal microbiota suspension provided by the Chinese fecal microbiota bank were delivered to the patient's ileocecal junction through the endoscopy channel. Subsequently, special drugs such as antibiotics were ceased, but low residue liquid diet, diuretic, improve circulation and other treatments were continued. The next day after FMT, the patient resumed bowel movements, accompanied by relief of abdominal pain and bloating symptoms. On the third day after FMT, the patient's was discharged after having a normal diet. One week after discharge, colonoscopy showed no obvious erosions were found in the colonic mucosa ( Figure. 3B). At the fourth week, the patient's weight increased by 2.5 kg, while CRP, PCT, BNP and ALB all returned to normal ranges ( Fig. 1. A, B). Cardiac ultrasound showed that the patient's LVEF increased to 50%. CT showed that pleural effusion disappeared, and intestinal atulence and peritoneal effusion decreased ( Fig. 2. C, D). During subsequent follow-up, the patient only had occasional slight bloating and no more severe symptoms under normal diet. The frequency and form of faeces returned to be normal, and the nutritional status was signi cantly improved. At the same time, he didn't experience symptoms of heart failure (HF) such as shortness of breath, legs edema. One year later, the patient underwent pericardectomy, but the severe and extensive calci cation prevent the pericardium from being completely removed. In the third year, the patient was re-admitted to the hospital due to similar symptoms. After examinations, the diagnosis was the same as before, and FMT was performed again. Until now, the patient has not experienced severe abdominal symptoms and is in good health.
This case report was approved by the Regional Ethics Review Board at Southwest Medical University (approval number 2019/101), and the patient gave written informed consent for participation and publication of this case report.

Discussion
We performed FMT on a patient who was diagnosed with chronic incomplete intestinal obstruction which may caused by CP and HF. Clinically, patients with CP or HF are usually in a state of liver and intestinal congestion, accompanied by anorexia, bloating and other abdominal symptoms. These symptoms lasted more than nine months in this patient, and there was no relieve in his symptoms after treatments. Next, colonoscopy revealed the scattered in ammation which may caused the severe symptoms. Previous studies have con rmed FMT can be used to intestinal in ammation, for example, Ding et al. 10 performed FMT on patients with carbapenem-resistant Enterobacteriaceae (CRE), and Blanchaert 11 concluded that FMT can treat ulcerative colitis (UC). Therefore, we performed FMT on this patient. Surprisingly, after FMT, the in ammation decreased and his clinical symptoms and cardiac function improved. We believe that CP prevented the blood from returning to the heart, leading to intestinal congestion and edema, weakening intestinal peristalsis and causing intestinal obstruction. The latter can cause intestinal ora disorders, BT and in ammation, which further exacerbates the cardiac insu ciency. His heart, intestine and ora seemed to form a vicious circle, which was blocked by the intervention of FMT.
One month after FMT, the ora analysis revealed both the structure and diversity of the patient's intestinal ora were similar to these of the donors. And previous studies have con rmed that a richer gut microbiome and a more reasonable composition of ora are important for the maintenance of the intestinal barrier, immune system and nutrient metabolism. 12,13 It is worth noting that the abundance of Bacteroides was signi cantly reduced after treatment. Bacteroides can decompose choline, carnitine and others and nally produce Trimethylamine N-oxide (TMAO), a key contributor to CV disease pathogenesis. 14,15 And the reduction of Bacteroides could partly explain the improvement of patients' heart function.
The results showed the predominant ora was Prevotella after FMT. A study on the relationship between dietary structure and intestinal ora revealed that Prevotella is closely related to a high-carb diet, which is called the "Mediterranean Diet". 16 It is recognized as the healthiest dietary structure in the world, because it can promote the optimization of the intestinal ora, such as increasing the diversity of the intestinal ora, improving the probiotic abundance and the concentration of fecal SFCAs. On the one hand, these products can promote the absorption of various nutrients such as amino acids, and improve glucose tolerance and blood lipid distribution. 17,18 On the other hand, they can improve the intestinal barrier function by affecting the permeability of intestinal epithelium and suppresses enteritis by regulating the balance of immune system. 19,20 Conclusion To sum up, when FMT restored the patients' intestinal ora imbalance, the intestinal functions are improved, including barrier, digestion and absorption. And in line with this, there was a relief in the patient's HF and an amazing improvement in his nutritional status, providing conditions for the operation. However, the berboard was not completely removed by the operation, so the factors restricting the heart still existed, resulting in his relapse one year later. Then we performed FMT for the second time and still achieved splendid results. And this case provides new ideas for the treatment of refractory incomplete intestinal obstruction, but the effect and safety need more clinical studies to verify.

Declarations
Availability of data and materials All data sets used and/or analyzed in this study are also available from the corresponding authors.
Ethics approval and consent to participate Not applicable.

Consent for publication
Not applicable.

Competing interests
The authors declare that they have no competing interests.