Volume 39, Issue 6 , Pages 726-730, June 2010
CT Angiography Followed by Endovascular Intervention for Acute Superior Mesenteric Artery Occlusion does not Increase Risk of Contrast-Induced Renal Failure
Article Outline
Abstract
Objectives
Acute superior mesenteric artery (SMA) occlusion can be diagnosed in an early phase by computed tomography (CT) angiography, which is also a prerequisite for endovascular intervention. However, the issue of development of postoperative permanent renal failure due to contrast-induced nephropathy has not been evaluated.
Design
Retrospective
Materials
A total of 55 patients with acute SMA occlusion were retrieved from the in-hospital register during a 4-year period between 2005 and 2009.
Methods
Glomerular filtration rate was calculated as a simplified variant of Modification of Diet in Renal Disease Study Group (MDRD).
Results
Preoperative renal insufficiency was found in 52%; advanced state in one patient. Creatinine was lower (p = 0.018) at discharge (median: 71 μmol L−1), compared to admission (median: 76 μmol L−1), in the 32 survivors exposed to repeated iodinated contrast media (median: 54.7 g iodine). No patient died due to renal failure or needed dialysis after endovascular intervention. Endovascular intervention was associated with a higher survival rate (p = 0.001).
Conclusion
Serious acute contrast-induced nephropathy was not found in patients diagnosed by CT angiography and treated by endovascular procedures for acute SMA occlusion. Elevated serum creatinine levels should not deter the clinician from ordering a CT angiography in patients with suspicion of acute SMA occlusion.
Keywords: Contrast-induced renal failure, Endovascular intervention, Superior mesenteric artery occlusion
Acute thrombo-embolic occlusion of the superior mesenteric artery (SMA) is one of the most lethal diseases in patients with acute abdomen. Recent developments in computed tomography (CT) technology1 have made it possible to diagnose this condition early, allowing time for mesenteric revascularisation. Indeed, a variety of acutely planned endovascular techniques have been developed from the information gathered from the CT angiography images.2 CT examination without use of intravenous contrast enhancement is associated with diagnostic delay and increased mortality.1 However, there are concerns regarding contrast-induced nephropathy (CIN) in these often elderly patients with concurrent cardiovascular disease undergoing both CT angiography and conventional angiography for treatment. Indeed, serum creatinine as a risk indicator is usually required by the radiologists prior to CT examination. There is a risk that patients with acute SMA occlusion may be disqualified for a proper CT angiography by the radiologists due to an elevated serum creatinine alone. In fact, it is not unlikely that elevated creatinine is common in these patients at admission due to the occurrence of dehydration, vomitus, diarrhoea, accumulation of fluid in the intestinal lumen and bowel wall oedema. The risk of CIN3 and permanent kidney damage may be high in patients diagnosed with acute SMA occlusion, who undergo both diagnostic CT angiography and therapeutic angiography. The main aim of the present study was to assess renal function before and after exposure to iodinated contrast media in patients undergoing endovascular intervention for acute SMA occlusion.
Patients and Methods
The primary catchment population was approximately 756 000 inhabitants (Swedish Central Bureau of Statistics; http://www.scb.se). The records of patients with diagnosis of acute SMA occlusion during a 4-year period between 1 November 2005 and 31 October 2009 were retrieved through a combined search of a local endovascular database and the in-hospital registry of Malmö University Hospital. The diagnosis of acute SMA occlusion (n = 55) was established after CT scan with intravenous contrast enhancement at initial or at re-evaluation in all but one patient, who was diagnosed at laparotomy.
Definitions
Glomerular filtration rate (GFR) was calculated as a simplified variant of Modification of Diet in Renal Disease Study Group (MDRD).4 All patients were white Caucasians and advanced renal insufficiency was defined as GFR < 25 mL min−1. Renal insufficiency by serum creatinine levels alone was defined as serum creatinine level >105 μmol L−1 in men and creatinine >90 μmol L−1 in women. The iodine (I) (g)/GFR (mL min−1) ratio at admission is an estimate for the risk of developing contrast-medium-induced nephropathy, and I-dose/GFR ratio ≥1.0 is considered to be a threshold value for a clear risk.5 Hypertension was defined as a systolic pressure exceeding 140 mmHg or a diastolic pressure exceeding 90 mmHg measured at least at two different occasions, a history of hypertension or treatment with anti-hypertensive medication. Ischaemic heart disease included previous myocardial infarction, angina pectoris or coronary intervention. Stroke included cerebral infarction or transitory ischaemic attack (TIA). The onset of abdominal pain was divided into acute (within 1 h) or insidious (more than 1 h). The nature of occlusion, embolic or thrombotic, was based on radiological findings at CT angiography and/or angiography, and/or clinical, surgery and/or autopsy data.
Statistical methods
Data management and statistical analysis were performed using SPSS for Windows, version 17.0 (SPSS, Chicago, IL, USA). Differences in proportions were analysed using chi-square or Fisher's exact test. Continuous variables were expressed in median and interquartile range (IQR), and differences were evaluated using Mann–Whitney U or Wilcoxon tecken-rang test. P < 0.05 was considered significant.
Results
Patient characteristics
Median age was 76 years (IQR: 67–84) and the proportion of women was 78% (43/55). The prevalence of hypertension was 50%, diabetes mellitus 18%, claudication 34%, stroke or transient ischaemic attack 14%, ischaemic heart disease 31% and previous vascular surgery 29%. The nature of occlusion was embolic in 53% and thrombotic in 47% of the cases. Synchronous emboli (n = 23) were found in 14/29 (48%) patients with embolic occlusion, and these were dislodged to the kidney (n = 11), leg (n = 5), arm (n = 2), spleen (n = 2), coeliac trunk (n = 2) and cerebellum (n = 1). Eight patients had renal emboli, of whom three had bilateral. Patients with atherosclerotic and acute thrombotic occlusive disease (n = 26), verified by CT angiography (n = 26) and/or angiography (n = 21), had either an SMA occlusion (n = 16) or an SMA stenosis (n = 10). The coeliac trunk was occluded in nine, stenotic in 14 and showed no significant stenosis in three patients.
Symptoms and signs
Symptom duration from the onset of disease to proper treatment was 47 h (IQR: 24–120) in patients with embolic versus 312 h (IQR: 48–720) for those with thrombotic occlusion (p = 0.001). Onset of disease was acute in 27 (49%) and insidious in 28 (51%) of patients, respectively. Vomitus occurred in 73% and diarrhoea in 55% of the patients on admission.
Treatment for acute embolic SMA occlusion
The following main procedures for embolic occlusion (n = 29) were performed: open SMA embolectomy (n = 8), endovascular aspiration SMA embolectomy from the groin (n = 9), endovascular mechanical fragmentation of embolus with Rotarex™ (Straub-Medical AG, Wangs, Switzerland) (n = 2) or AngioJet™ Ultra (MEDRAD Interventional/Possis, Minneapolis, MN, USA) (n = 1) devices. Intra-arterial thrombolysis with 39.5 mg of alteplase (Actilyse; Boehringer Ingelheim, Stockholm, Sweden) was administered locally for massive leg embolisation in one patient with a CT-verified embolic SMA occlusion as well. The patient had severe leg ischaemia but was apparently asymptomatic from the abdomen. After successful thrombolysis for leg emboli, control angiography of the SMA showed that the embolus was totally dissolved. Adjunctive intra-arterial thrombolysis in the SMA was performed in five patients. Three primary bowel resections were performed, one after a failed endovascular procedure causing a long dissection in the SMA. Conservative treatment with full dose of low-molecular-weight heparin resulted in slow resolution of abdominal symptoms and discharge in a 92-year-old woman. One patient underwent explorative laparotomy only. Palliative treatment without explorative laparotomy was performed in three patients. Two patients were converted from an open to endovascular procedure.
Treatment for acute thrombotic SMA occlusion
For thrombotic occlusion (n = 26), the following main procedures were performed: stenting of the SMA (n = 18), thrombolysis of an acutely thrombosed stent in the SMA, followed by re-stenting (n = 1), percutaneous angioplasty (PTA; n = 1) and primary bowel resection (n = 2). One patient underwent a diagnostic angiography only, which showed peripheral occlusive lesions in the SMA, considered difficult-to-treat endovascular, and this patient was therefore treated with bowel resection. Three patients were managed by palliative treatment without explorative laparotomy. The endovascular interventions were preceded by access through the brachial (n = 11), femoral (n = 13) and intra-abdominal SMA (n = 6) route. SMA stenting was performed from an antegrade (n = 16) or intra-abdominal retrograde approach (n = 3). The stented occlusive lesions of the SMA (n = 19) were treated by stentgrafts (n = 4), balloon-expandable stents (n = 13) and self-expandable stents (n = 13). Three patients were converted from endovascular to an open vascular procedure.
Pre- and postoperative renal function
Median GFR at admission was 60.5 mL min−1 (IQR: 42.0–83.5). One patient was classified as having an advanced renal insufficiency. According to serum creatinine values alone, renal insufficiency was found in 52% (28/54). The median creatinine level at admission in 32 survivors undergoing endovascular intestinal revascularisation or angiography-assisted open vascular procedure was 76 μmol L−1 (IQR: 63–114; range: 44–169). These patients were first exposed to 27 g of iodinated contrast media during the CT angiography scan, and then to another 27.7 g iodine (IQR: 20.9–49.8) iodine during the angiography series. One patient underwent carbon dioxide angiography, supplemented with 4.0 g iodine. The prevalence of I-dose/GFR ratio ≥1.0 at admission was 14/32 (44%). The median creatinine level at discharge, compared to admission levels, was lower, 71 μmol L−1 (IQR: 60–81) (p = 0.018). The comparative creatinine values at admission and at discharge in these patients are displayed with a box plot graph (Fig. 1). The patient with an outlier value at discharge, 110 μmol L−1, 15 days postoperatively, compared to 93 μmol L−1 at admission, had a creatinine value of 82 μmol L−1 2 months postoperatively. The patient with an extreme value at discharge, 156 μmol L−1, 8 days postoperatively, compared to 84 μmol L−1 at admission, had a creatinine value of 123 μmol L−1 2 months postoperatively. The median creatinine at admission for the five survivors with diabetes mellitus who underwent endovascular intervention was 114 μmol L−1, compared to 76 μmol L−1 at discharge (p = 0.50). Four patients with emboli to the kidneys survived after endovascular intervention, of whom two had bilateral emboli: the median creatinine values at admission and discharge were 120 μmol L−1 and 76 μmol L−1, respectively (p = 0.27). One of those four patients had an increase in creatinine from 107 to 154 μmol L−1 at discharge. No study patient died due to renal failure or needed dialysis after endovascular intervention.
Figure 1
Creatinine values at admission and at discharge after endovascular intervention for acute SMA occlusion in 32 patients. Box plot graph showing median values and IQRs of creatinine. Line across the box indicate the median, the box represents IQR, and the whiskers are lines that extend from the box edge to the highest and lowest values, excluding outliers and● extremes∗. A significant decrease (p = 0.018) in creatinine values was found. Note the decreased variability of creatinine values at discharge.
In-hospital mortality
In-hospital mortality was 33% (18/55). Compared to the whole study group, successful intestinal revascularisation (n = 37) and attempting endovascular intervention (n = 29) were associated with lower mortality rates of 11% (p < 0.001) and 17% (p = 0.001), respectively. Performance of bowel resection (p = 0.20) and check/second-look laparotomy (p = 0.064) resulted in a mortality of 44% (8/18) and 48% (10/21), respectively. Six out of 35 patients died after attempting endovascular or hybrid intervention: the death causes were intestinal infarction (n = 2), intestinal fistula (n = 2), short bowel syndrome (n = 1) and pneumonia (n = 1). Survival according to treatment performed is summarised in Fig. 2.
Figure 2
Management and survival of patients with acute SMA occlusion in Malmö 2005–2009. Hybrid means both open and endovascular surgery. Performance of bowel resection was performed in five (62%)#, four (66%)¤ and five (17%)* patients, respectively.
Discussion
More than 50% of the study patients had preoperative renal insufficiency. Elevated serum creatinine at admission is, however, seldom caused by a known renal insufficiency disorder among patients with acute SMA occlusion.1 Instead, the increase in creatinine reflects a state of dehydration. In addition, the study patients often had various risk factors for developing CIN3 such as old age, atrial fibrillation and cardiac failure. The radiologists are very aware of CIN, which is reported to occur in a dose-dependent manner in an inverse relation to the patient's GFR. However, CT angiography is not only the best diagnostic tool in patients with acute SMA occlusion, but it may also diagnose the nature of vascular pathology for better operative planning. When a diagnosis is established by CT angiography, there is rarely any obvious contraindication to endovascular treatment, even if there is an inherent increased risk of nephropathy after repeat intra-arterial contrast media injections above the renal arteries.6 Somewhat unexpectedly, creatinine was significantly lower at discharge than at admission in the 32 survivors undergoing intestinal revascularisation, despite an I-dose/GFR ratio ≥1.0 in 44% and repeated exposures of iodinated contrast media by the intravenous and then the intra-arterial route during CT and angiography series, respectively. Furthermore, patients with concomitant emboli to the kidneys should be regarded as extreme high-risk patients for developing severe renal failure; however, only one study patient had an increase of creatinine values during hospital stay. In fact, renal function dynamics with a decreased creatinine at discharge after a similar iodinated contrast dose exposure has also been observed in survivors after endovascular repair of ruptured abdominal aortic aneurysm.7 The incidence and serious consequences of administrated intravenous iodinated contrast seem to be much less common than previously thought of.8 In fact, most episodes of CIN are self-limited, resolving within 1–2 weeks, and seldom leads to permanent kidney damage. One case-control study has shown that CT angiography did not increase the risk for acute nephropathy.9 Of note, no study patient died due to renal failure or needed dialysis after endovascular intervention. Similar results have been reported in 301 high-risk patients for contrast-medium-induced nephropathy, with GFR <60 mL min−1, undergoing multidetector row CT with intravenous iodinated contrast, where no cases of acute renal failure requiring specific medical treatment or haemodialysis were observed.10
Preventive measures should be taken, however, to reduce the incidence of CIN. In an emergency situation, intravenous rehydration with isotonic saline solution, at least 1 mL kg−1 body weight per hour, before and after each iodinated contrast media exposure is most important. Second, a reduction in contrast dose without compromising imaging quality may be feasible in patients with low flow states and in skinny individuals.11 Esteban et al. have suggested the use of 30 mL 1.0 M gadobutrol as contrast medium for CT aortography in patients with contraindications to iodine contrast media including renal impairment.12 Gadobutrol is a non-ionic gadolinium contrast medium primarily intended for magnetic resonance imaging, but it attenuates radiation photons as well. The rationale should be that gadolinium-based contrast agents appear approximately 20 times safer than iodinated agents in patients with impaired renal function.13 However, comparisons between gadolinium and iodine contrast medium regarding CIN must be made at doses with both equal-attenuating and equal-molecular doses, and gadolinium contrast medium appears to be more nephrotoxic than modern iodine contrast medium.14 Therefore, gadolinium contrast medium should definitely not replace iodine contrast medium in patients with impaired renal function.
An early diagnosis by CT angiography and the development of endovascular techniques have had a great impact on survival of patients with acute SMA occlusion. The clinician in charge needs to take full responsibility for the patient and be very clear about the questions asked in the referral letter for CT angiography. It is very important to have a direct contact with the radiologist so that intravenous contrast is administrated despite an elevated creatinine.1 The sometimes life-saving information gathered from the CT angiography in various emergent abdominal conditions should be weighed against the rather low incidence of CIN3 and the often mild and transient forms.
In conclusion, serious acute CIN was not found in patients diagnosed by CT angiography and treated by endovascular procedures for acute SMA occlusion. Elevated creatinine levels at admission, which was present in the majority of study patients, should not deter the clinicians from ordering a CT angiography in suspected cases.
Conflict of Interest/Funding
None.
References
- Wadman M, Block T, Ekberg O, Elmståhl S, Syk I, Acosta S. Impact of MDCT with intravenous contrast on the survival in patients with acute superior mesenteric artery occlusion. Emerg Radiol 2010 (In Press).
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- . Contrast-induced nephropathy: the wheel has turned 360 degrees. Acta Radiol. 2008;49:646–657
- Simple Cystatin C-based prediction equations for glomerular filtration rate compared with the modification of diet in renal disease prediction equation for adults and the Schwartz and the Counahan–Barratt prediction equations for children. Clin Chem. 2005;51:1420–1431
- . Contrast-medium-induced nephropathy correlated to the ratio between dose in gram iodine and estimated GFR in ml/min. Acta Radiol. 2005;46:830–842
- . Risk of contrast-induced nephropathy with the intravenous administration of iodinated contrast media. Radiology. 2007;243:622–628
- . Predictors for outcome after open and endovascular repair of ruptured abdominal aortic aneurysm. Eur J Vasc Endovasc Surg. 2007;33:277–284
- . Contrast-induced nephropathy after intravenous administration – fact or fiction?. Radiol Clin North Am. 2009;47:789–800
- CT angiography for intracerebral hemorrhage does not increase risk of nephropathy. Stroke. 2009;40:2393–2397
- . Risk of contrast-medium-induced nephropathy in high-risk patients undergoing MDCT – A pooled analysis of two randomized trials. Eur Radiol. 2009;19:891–897
- Abdominal multidetector CT in patients with varying body fat percentages: estimation of optimal contrast material dose. Radiology. 2008;249:872–877
- . One-molar gadolinium chelate (gadobutrol) as a contrast agent for CT angiography of the thoracic and abdominal aorta. Eur Radiol. 2007;17:2394–2400
- . Safety of gadolinium contrast angiography in patients with chronic renal insufficiency. J Vasc Surg. 2003;2003(38):313–318
- . Gadolinium contrast media are more nephrotoxic than a low osmolar iodine medium employing doses with equal X-ray attenuation in renal arteriography: an experimental study in pigs. Acad Radiol. 2004;2004(11):1219–1228
PII: S1078-5884(10)00053-5
doi:10.1016/j.ejvs.2010.01.017
© 2010 European Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
Volume 39, Issue 6 , Pages 726-730, June 2010
