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Ann Thorac Surg 2001;72:1583-1586
© 2001 The Society of Thoracic Surgeons

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Original article: cardiovascular

Diagnosis and treatment of nonocclusive mesenteric ischemia after open heart surgery

^a Department of Cardiothoracic Surgery, University Hospital of Münster, Münster, Germany
^b Institute for Clinical Radiology, University Hospital of Münster, Münster, Germany
^c Department of Anesthesiology and Intensive Care Medicine, University Hospital of Münster, Münster, Germany

Accepted for publication June 28, 2001.

* Address reprint requests to Dr Schmid, Department of Cardiothoracic Surgery, University Hospital, Albert-Schweitzer-Str 33, D-48129 Münster, Germany
e-mail: schmid{at}uni-muenster.de

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Acute nonocclusive mesenteric ischemia (NOMI) is a rare but often fatal event after cardiac surgery.

Methods. Twenty patients with ongoing ileus after cardiac surgery despite maximal laxative treatment underwent selective mesenteric angiography. In cases of pathological radiographic findings, papaverine was continuously administered via an intraarterial perfusion catheter.

Results. Severe NOMI was confirmed in seven patients (mean lactate: 6.9 ± 8.3 mg/dL), mild to moderate findings in another seven (mean lactate: 1.4 ± 1.1 mg/dL). One patient had thromboembolic occlusion of the superior mesenteric artery; five patients demonstrated normal imaging findings. In nine of fourteen patients (64%) treated with papaverine, symptoms improved within hours (defecation occurred after 4–29 hours, mean 13 ± 8.1 hours). No side effects or complications occurred in connection with the papaverine treatment. The clinical condition of five patients deteriorated. Four patients underwent laparotomy with creation of an ileostomy or colostomy, two of whom presented with severe intestinal ischemia and later died. One patient died prior to laparotomy.

Conclusions. Selective mesenteric angiography with continuous papaverine administration is a simple, fast, and effective diagnostic and therapeutic tool to reduce the need for laparotomy for symptoms of ileus after open-heart surgery.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Open-heart surgery employing cardiopulmonary bypass (CPB) has become a relatively safe routine procedure. Among the few complications that can lead serious sequelae are those involving the gastrointestinal structures. Such complications occur in 0.6% to 2% of patients and include acute mesenteric ischemia in about one-fourth of cases [1–6]. Mesenteric ischemia is associated with an extraordinary mortality rate because intestinal gangrene may develop. Even in cases of splanchnic vasospasm without occlusion of the great intestinal vessels, nonocclusive mesenteric ischemia (NOMI), mortality rates from 30% to 93% have been reported [1, 7–9]. Because of the rarity of this disease, it is difficult to assess clinical risk factors. Most likely, reduced blood supply to the bowels is caused either by low cardiac output or by the vasoconstrictive drugs used to treat it. Other risk factors include renal disease, diabetes mellitus, prolonged CPB time, and the use of an intraaortic balloon pump [1, 4, 6, 10]. Regardless of the underlying pathophysiology, the prognosis crucially depends on rapid diagnosis and adequate treatment.

This is a report of a nonrandomized study to evaluate whether selective mesenteric angiography could detect NOMI after open-heart surgery and whether intramesenteric infusion of a potent vasodilator such as papaverine can relieve the dangerous vasospasm in these cases.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Patient demographics
Between November 1997 and July 1999, twenty of 2,300 patients (0.87%) underwent selective angiography of the superior mesenteric artery for suspicion of mesenteric hypoperfusion after open-heart surgery with nonpulsatile CPB. There were 16 men and 4 women, with an average age of 67 ± 14 years. The surgical procedures performed were coronary artery bypass surgery (CABG) in fourteen patients, aortic valve replacement (AVR) in two patients, heart transplantation in three patients, and implantation of a left ventricular assist device in one patient. Mean operation time was 192 ± 57 minutes; mean CPB pump time, 90 ± 43 minutes. Ejection fraction of the patients with CABG and AVR was 54% on average, ranging from 34% to 83%. All patients were hemodynamically stable; however, six were treated with epinephrine (0.08 ± 0.08 µg/kg per minute), and four had been provided with an intraarterial balloon pump after surgery. At the time of angiography, eighteen patients were extubated and two were still respirator dependent.

Diagnostics
Indication for selective angiography of the mesenteric artery was established if at least one of four possible indicators for mesenteric ischemia was present: no defecation later than 3 days after surgery despite maximal laxative treatment, severe abdominal bloating with a considerably distended belly, clinical and radiologic signs of paralytic ileus, borderline or elevated serum lactate. Abdominal pain was not a prominent feature in the early clinical course of these patients.

Mesenteric angiography was performed via a femoral artery. A 5 French catheter (Cordis, Haan, Germany) was introduced using Seldinger’s technique and advanced into the origin of the superior mesenteric artery. The artery was then visualized by injection of radiopaque contrast medium (Immeron, Bracco-Byk Gulden, Konstanz, Germany) employing digitized subtraction angiography. The first aim was to exclude thromboembolic obstruction of the proximal artery amenable to surgical treatment. Thereafter, NOMI was diagnosed if the following pathological findings were evident (according to the classification of Kaleya and coworkers [8] and Clark and Gallant [11]): (a) narrowing of the origins of branches of the superior mesenteric artery; (b) irregularities in the intestinal branches; (c) spasm of the arcades; (d) impaired filling of the intramural vessels; (e) mesenteric blood flow less than 50% of expected flow rate. NOMI was considered severe if all branches of the superior mesenteric artery were narrowed, or if less than 50% of the arterial arcades were visible during angiography. Mild to moderate NOMI was noted if only some of the major branches were involved, or if more than 50% of the arterial arcades and the intramural vessels seemed well perfused.

Papaverine treatment
With angiographic evidence of NOMI, the inserted catheter was used for immediate intraarterial infusion of papaverine into the superior mesenteric artery. The attempted dosage was 0.7 mg/kg per hour (60 mg/h) diluted to a concentration of 1.0 mg/mL.

Control mesentericography was scheduled 24 to 36 hours after initiation of the papaverine infusion, depending on the patient’s clinical status. Reasons for an early control angiography were either progressive worsening with development of an acute abdomen mandating urgent surgical intervention or successful defecation with a considerable improvement of the patient’s gastrointestinal condition to prove efficacy of the papaverine treatment. The catheter was removed either after angiography or after successful defecation.

Statistics
Patient data were analyzed for range, mean, and standard deviation. Serum lactate levels were compared using the Kruskal-Wallis test; p values less than 0.05 was considered significant.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Diagnosis
All patients presented with severe bloating and failure to defecate for 4.9 ± 2.4 days following open-heart surgery despite intensive laxative treatment. Angiography of the superior mesenteric artery confirmed the diagnosis of NOMI in fourteen patients (70%); severe findings were evident in seven cases and mild to moderate findings in the other seven cases. Thromboembolic occlusion of the superior mesenteric artery was diagnosed in one patient. In five patients, mesenteric angiography appeared normal.

The severity of NOMI based on angiography ran in parallel with the average serum lactate levels. Patients with severe NOMI had an average serum lactate level of 6.9 ± 8.3 mg/dL, whereas those with mild to moderate NOMI had a serum lactate level of only 1.4 ± 1.1 mg/dL. However, a statistically significant difference between these groups could not be found (p = 0.12; Fig 1).

View larger version (9K): [in this window] [in a new window]   Fig 1. Serum lactate levels in patients with radiologically proven mild to moderate and severe nonocclusive mesenteric hypoperfusion (p = 0.12). (NOMI = nonocclusive mesenteric ischemia.)

View larger version (90K): [in this window] [in a new window]   Fig 2. Radiologic improvement of severe NOMI (left) after intramesenteric papaverine treatment (right).

In nine cases (64%), the papaverine infusion led to improvement of the patient’s clinical condition and abdominal status within a short time. Defecation occurred after 12 ± 8.7 h (range 4 to 29 hours). Control mesenteric angiography was performed in five patients 26 ± 15 hours after initiation of the treatment. Improved mesenteric perfusion was evident in four patients (80%); only one patient had findings identical to those on the first angiography. No side effects or complications occurred in conjunction with the papaverine treatment (Fig 2).

In five cases (36%), the patient’s clinical condition deteriorated despite papaverine treatment. One patient died prior to surgery as a result of multiorgan failure; another patient underwent emergency laparotomy, which confirmed the diagnosis of NOMI. Despite creation of an ileostomy, he died one day later from multiorgan failure. In the other three patients, laparotomy was performed on an urgent basis because control mesenteric angiography showed no improvement. One patient had a partially necrotic small intestine; he died during postoperative recovery period in the hospital. The other two patients showed only distended bowels. All three patients received colostomies, which were closed 6 months later in the two patients who survived. The patient with occlusion of the superior mesenteric artery was immediately transferred to the operating room. An ischemic colon was found at laparotomy and a hemicolectomy as well as a thrombectomy of the superior mesenteric artery was performed.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
Since the first description of NOMI by Ende in 1958 [13], its incidence after open-heart surgery has been reported to be about 0.05% to 0.1%. This is about 10 times lower than observed in our institution; we think that our liberal use of early angiography explains the difference. When analyzing our few cases for possible risk factors, we did not find significant differences from our total patient population, except that the average patient age was higher (67 ± 14 years versus 63.1 ± 12.8 years).

Early diagnosis of NOMI is essential to lower mortality and postoperative morbidity. Irreversible intestinal necroses will develop after intestinal ischemia of more than 2 to 3 hours. Postoperative cardiac patients who have been extubated and are able to communicate can facilitate the physical examination. Nonetheless, physical findings may be non-specific and laboratory parameters are of limited value. Elevated serum lactate, acidosis, and an increased creatinine kinase level are indicative but do not prove NOMI [1, 5, 9, 10, 12]. In our patients with severe NOMI, we noticed a tendency toward a high concentration of serum lactate, but this was not statistically significant. Abdominal ultrasound and plain abdominal x-rays show positive signs of ileus, subileus, and free abdominal fluid in 80% of cases, but these findings do not prove NOMI [10]. Therefore, mesenteric angiography is necessary to visualize the typical pattern of peripheral vasoconstriction that occurs in over 90% of cases [2, 5, 7, 10–11]. In our experience, diagnosis of NOMI was established by angiography in 64% of cases; in five patients mesenteric perfusion appeared to be normal. These results render mesenteric angiography a valuable tool for diagnosis.

The reported mortality rate for NOMI is 70% to 80% if left untreated for several days; more, if treatment is delayed further [1, 6, 7]. In most cases reported in the literature, and in our institution, the interval between cardiac surgery and angiography is 5 days [1, 6]. In most cases, this seems early enough to identify NOMI before bowel infarction occurs [7, 13, 14].

In 1977, Boley and associates demonstrated that persistent mesenteric vasoconstriction can be relieved by selective injection of papaverine into the superior mesenteric artery [7]. By this means, he and others achieved a survival rate of 60% in patients suffering from NOMI treated with papaverine at a dose of 60 mg/h [6, 7]. Clark demonstrated a successful outcome in 45% of cases treated with papaverine (30 to 60 mg/h) or prostaglandin E₂ (0.6 to 1.5 mg/h) [11]. Both Eker and colleagues [2], and Niederhäuser and associates [5], reported single survivors after treatment with 10 mg/h and 30 mg/h papaverine, respectively. Stöckmann and colleagues reported survival of eight of their nine patients treated with prostaglandin E₂ (60 µg/24 h for 3 days) [10].

In our institution, nonsurgical treatment was successful in 64% of our patients. Although more than 90% of the papaverine is inactivated with each passage through the liver, we noticed no side effects or complications related to the treatment. Nevertheless, as large doses may be infused directly into the mesenteric circulation, the patient’s heart rate and blood pressure should be carefully monitored. For this reason, we keep patients in our intermediate care unit during this treatment, and we administer prophylactic antibiotics. The duration of the papaverine treatment is based on the patient’s condition. Because the effect of papaverine is usually long-lasting, it can be terminated as soon as sufficient bowel function is restored and defecation is possible. We have not observed any recurrence of ileus symptoms. The clinical improvement in patients in whom angiography did not show an improved mesenteric perfusion is difficult to explain. One may speculate that the clinical findings in patients with NOMI are multifactorial.

If a patient fails to improve within 2 days, we favor control angiography and continued intramesenteric infusion. Published reports have stated the infusion should be maintained for at least 5 days; we empirically decided to continue papaverine administration for a maximum of 7 days, even if most of our patients had restored bowel function within 1 or 2 days. In fact, the longest drug interval was 5 days, 2 h [5, 7, 8].

In critical situations, abdominal surgery is scheduled without delay. Patients who needed laparotomy and demonstrated intestinal necrosis died, which was to be expected; those with normal findings experienced uneventful recovery. Accordingly, the calculated mortality rate in patients who required urgent laparotomy was 50%, similar to the results from Stöckmann and colleagues, who reported a mortality rate of 66% after laparotomy [10]. Therefore, like others, we feel that the ideal patient should be studied early, before signs of an acute abdomen develop.

In cases of suspected NOMI, selective arterial mesenteric angiography with consecutive perfusion of papaverine is a simple, fast, and effective diagnostic and therapeutic tool that permits differentiation between occlusive and nonocclusive conditions. Local papaverine infusion can avoid unnecessary laparotomy and allow regression of paralytic ileus. A low risk and a rather high success rate favor liberal, and especially early, use of angiography to reduce the excessively high mortality rate associated with NOMI.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

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3. Krasna M.J., Flancbaum L., Trooskin S.Z., et al. Gastrointestinal complications after cardiac surgery. Sugery 1988;104:773-780.
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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Hans H. Scheld Christof Schmid Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Klotz, S. Articles by Schmid, C. Search for Related Content PubMed PubMed Citation Articles by Klotz, S. Articles by Schmid, C. Related Collections Cardiac - other