Importance of diastolic velocities in the detection of celiac and mesenteric artery disease by duplex ultrasound

Mesenteric and renal arterial duplex ultrasound: A review

Duplex ultrasound examinations of the mesenteric and renal circulations are commonly used to detect disease as well as to follow up patients after open surgery or endovascular intervention. The aims of this review were to present essential elements of these duplex ultrasound examinations as well as conduct a literature review of diagnostic criteria. Documentation of appropriate images and data will aid in an accurate interpretation. Spectral Doppler waveforms from various segments of these arterial systems can contribute both direct and indirect evidence of the presence of disease. Various studies have validated the duplex ultrasound diagnostic criteria which more recently have expanded to include specific criteria for stented vessels. This review presents a summary of the fundamental exam components and diagnostic criteria utilized for mesenteric and renal duplex ultrasound.

European guidelines on chronic mesenteric ischaemia - joint United European Gastroenterology, European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Gastrointestinal and Abdominal Radiology, Netherlands Association of Hepatogastroenterologists, Hellenic Society of Gastroenterology, Cardiovascular and Interventional Radiological Society of Europe, and Dutch Mesenteric Ischemia Study group clinical guidelines on the diagnosis and treatment of patients with chronic mesenteric ischaemia

Chronic mesenteric ischaemia is a severe and incapacitating disease, causing complaints of post-prandial pain, fear of eating and weight loss. Even though chronic mesenteric ischaemia may progress to acute mesenteric ischaemia, chronic mesenteric ischaemia remains an underappreciated and undertreated disease entity. Probable explanations are the lack of knowledge and awareness among physicians and the lack of a gold standard diagnostic test. The underappreciation of this disease results in diagnostic delays, underdiagnosis and undertreating of patients with chronic mesenteric ischaemia, potentially resulting in fatal acute mesenteric ischaemia. This guideline provides a comprehensive overview and repository of the current evidence and multidisciplinary expert agreement on pertinent issues regarding diagnosis and treatment, and provides guidance in the multidisciplinary field of chronic mesenteric ischaemia.

Doppler Waveform Characteristics in the Celiac and Superior Mesenteric Arteries in Normal Children and Adults with the Use of Duplex Ultrasound

Purpose

To compare and contrast the flow patterns in celiac artery (CA) and superior mesenteric artery (SMA) in normal children to those in normal adults with the use of duplex ultrasound techniques.

Methods

Thirty male subjects were entered prospectively to the study. Peak systolic velocities and diameter at the origin of CA and SMA were recorded while the subject was fasting for at least 4–6 hr. The Human Ethics Committee at the Faculty of Allied Health Sciences-Kuwait University approved the study. Informed consent form was obtained from all subjects.

Results

There were 15 healthy male adults. Their average age (yr ± SD) was 22.7 ± 4.7 and their average body mass index (kg/m2 ± SD) was 23.5 ± 2.1. There were 15 healthy male children. Their average age (yr ± SD) was 7.2 ± 2.92, and their average body mass index (kg/m2 ± SD) was 18.5 ± 4.8. The average diameters (cm ± SD) of CA and SMA in adults were 0.73 ± 0.8 and 0.76 ± 0.11, and the average peak systolic velocities (cm/s ± SD) were 113 ± 17.5 and 145 ± 25.8, respectively. However, the average diameter (cm ± SD) of CA and SMA in children was 0.52 ± 0.06 and 0.53 ± 0.06, and the average peak systolic velocities (±SD, cm/s) of CA and SMA were 179.5 ± 39.5 and 175 ± 31.7. respectively. Paired student's t-test showed no statistical significance between the two groups. Coefficient of variation for diameter calculation and velocity measurement was <10%.

Conclusion

The peak systolic velocities in normal children at the superior mesenteric artery and celiac artery are slightly greater than in normal adults but it did not exceed 200 cm/sec in CA and 275 cm/sec in SMA. The Doppler waveforms are still within normal range in both groups despite the caliber of the vessels being smaller in children. Most probably greater velocities in children are caused by the high pressure of the transducer in superficially located vessel inducing flow disturbances.

Vascular imaging of the mesenteric vasculature

Imaging of the mesenteric vasculature is crucial in diagnosing vascular disease of the gastro-intestinal tract such as acute or chronic mesenteric ischemia caused by arterial stenosis, embolism or thrombosis, mesenteric vein thrombosis and mesenteric aneurysm or dissection. The reference standard for imaging of the mesenteric vasculature is digital subtraction angiography. However, modalities as duplex ultrasonography, computed tomography angiography and magnetic resonance angiography are developing rapidly and may provide accurate imaging non-invasively. This review provides an up-to-date overview of the anatomic resolution, clinical application, emerging techniques and future perspectives of these four radiological modalities for imaging of the mesenteric vasculature.

Hunger Games: Interactive Ultrasound Imaging for Learning Gastrointestinal Physiology

Ultrasound is playing an increasingly important role in medical student education. Although most uses of ultrasound have focused on learning purely anatomic relationships or augmentation of the physical examination, there is little documentation of the value of ultrasound as a learning tool regarding physiology alone or in association with anatomy. We devised an interactive learning session for first-year medical students using ultrasound to combine both anatomic and physiologic principles as an integration of gastrointestinal and vascular function. The incorporation of our activity, The Hunger Games, provides the foundation for a powerful integration tool for medical student education.

Subject body mass index affects Doppler waveform in celiac artery by duplex ultrasound

OBJECTIVE

The aim of this study is to evaluate the effect of body mass index (BMI) on peak systolic velocity (PSV) recording in the celiac artery (CA).

SUBJECTS & METHODS

Forty male participants were entered prospectively into the study. The subjects were divided into two groups according to their body mass index. Group A included subjects with BMI ≤25 Kg/m(2) and those in group B with BMI >25 Kg/m(2). The diameter and PSV at the origin of CA of subjects in both groups were recorded while the subject positioned in supine and during expiration phase and fasted for 4 hours using duplex ultrasound. Both groups were matched for age and sex. Independent Student's t-test was used to test if there is any statistical significance between diameter and PSV in both groups.

RESULTS

Group A's, average age (year, ±SD) was 29.35±1.35 and average BMI (Kg/m(2), ±SD) was 23.1±1.60. Group B's, average age was 30±2.1 and their average BMI was 31±5.1. The average diameter (cm, ±SD) of CA in group A was 0.66±0.076 and in group B was 0.80±0.066. However, the average PSV (cm/s, ±SD) was 117±28.1 in group A and 102±12.4 in group B. Independent student t-test showed statistical significance between both groups for the diameter (p=0.005) and just reached statistical significance for PSV (p=0.049).

CONCLUSION

Subjects with higher BMI showed reduced PSV due to a larger CA diameter and probably due to more fatty tissue accumulation around the CA origin.

Mesenteric/celiac duplex ultrasound interpretation criteria revisited

BACKGROUND

Several published studies with a small sample size have reported differing results of duplex ultrasound (DUS) utilizing different threshold velocities in detecting significant stenosis of superior mesenteric (SMA) or celiac arteries (CA). The present study is based on the largest number of mesenteric duplex/angiography correlations reported to date for the diagnosis of SMA/CA stenosis.

METHODS

One hundred fifty-three patients (151 SMA and 150 CA) had both DUS and arteriography. Receiver operator curves (ROC) were used to analyze peak systolic velocity (PSV), end diastolic velocity (EDV), and SMA or CA/aortic PSV ratio in detecting ≥50% and ≥70% stenosis.

RESULTS

For SMA (151 arteries: 84 with ≥50% stenosis [54 of which had ≥70% stenosis] based on angiography): the PSV threshold that provided the highest overall accuracy (OA) for detecting ≥50% SMA stenosis was ≥295 cm/s (sensitivity [sens.] 87%, specificity [spec.] 89%, and OA 88%); and for detecting ≥70% SMA, it was ≥400 cm/s (sens. 72%, spec. 93%, and OA 85%). The EDV threshold that provided the highest OA for detecting ≥50% stenosis was ≥45 cm/s (sens. 79%, spec. 79%, and OA 79%); and for ≥70% stenosis was ≥70 cm/s (sens. 65%, spec. 95%, and OA 84%). ROC analysis showed that PSV was better than EDV and SMA/aortic PSV ratio for ≥50% stenosis of SMA (P = .003 and P = .0005). For celiac arteries (150 arteries: 105 with ≥50% stenosis [62 of which had ≥70% stenosis]): the PSV threshold that provided the highest OA for ≥50% stenosis was ≥240 cm/s (sens. 87, spec. 83%, and OA 86%); and for ≥70% stenosis was ≥320 cm/s (sens. 80%, spec. 89%, and OA 85%). The EDV threshold that provided the highest OA for ≥50% stenosis was ≥40 cm/s (sens. 84%, spec. 48%, and OA 73%); and for ≥70% stenosis was ≥100 cm/s (sens. 58%, spec. 91%, and OA 77%). ROC analysis showed that PSV was better than EDV and SMA/aortic PSV ratio for ≥50% stenosis of CA (P < .0001 and P = .0410.)

CONCLUSIONS

PSV values can be used in detecting ≥50% and ≥70% SMA/CA stenosis and were better than EDVs and ratios. Previously published data must be validated in individual vascular laboratories. Our results will need prospective validation.

Abdominal angina

Abdominal angina is an underrecognized cause of postprandial abdominal pain and weight loss. Diagnosis is often delayed and requires both a careful exclusion of more common causes and a high degree of clinical suspicion, based on the patient's age, the coexistence of multiple risk factors for atherosclerosis, and the presence of vasculopathy in other districts. Appropriate investigations include duplex ultrasound, traditional angiography, magnetic resonance angiography, computed tomography angiography, and tonometry. The purpose of this review is to discuss the pathophysiology and clinical presentation of chronic mesenteric ischemia and to suggest a diagnostic flowchart for this complex condition.

Doppler sonographic criteria for the diagnosis of inferior mesenteric artery stenosis

OBJECTIVE

The purpose of this study was to define the optimal Doppler criteria for the diagnosis of inferior mesenteric artery (IMA) stenosis in patients with suspected chronic mesenteric ischemia (CMI).

METHODS

A retrospective review of 205 dedicated color and pulsed Doppler sonographic studies of mesenteric arteries was performed in 205 patients. All studies were performed in patients with suspected CMI. Correlative angiography was available in 50 patients.

RESULTS

The IMA was visualized in 176 of 205 Doppler sonographic examinations (86%) and in 92% of the correlative studies. The visualization rate for the detection of a patent IMA by Doppler sonography in this series was 90%. The ranges of the peak systolic velocity (PSV), end-diastolic velocity (EDV), and mesenteric-aortic velocity ratio (MAR) in the nonstenotic IMA were 70 to 200 cm/s, 0 to 33 cm/s, and 0.7 to 3.7, respectively. The ranges of the PSV, EDV, and MAR in IMA stenosis were 200 to 485 cm/s, 0 to 177 cm/s, and 0.69 to 8.1. The threshold values for severe IMA stenosis by logistic regression analysis (n = 42) were as follows: PSV, greater than 200 cm/s; EDV, greater than 25 cm/s; and MAR, greater than 2.5, with sensitivities of 90%, 40%, and 80%; specificities of 97%, 91%, and 88%; positive predictive values (PPVs) of 90%, 57%, and 67%; negative predictive values (NPVs) of 97%, 83%, and 93%; and accuracy of 95%, 79%, and 86%, respectively.

CONCLUSIONS

We found that a PSV of greater than 200 cm/s was the best criterion for the diagnosis of IMA stenosis. The sensitivity, specificity, PPV, NPV, and accuracy for the PSV were 90%, 97%, 90%, 97%, and 95%, respectively.

Isolated spontaneous dissection of the superior mesenteric artery treated by percutaneous stent placement: case report

Acute ischemia due to spontaneous dissections of the superior mesenteric artery are uncommon events, with sporadic reports. Therapeutic options include clinical management, direct artery repair, bowel resection, and more recently, endovascular stenting. We present a case of abdominal pain due to superior mesenteric artery spontaneous isolated dissection treated with stent placement and with a favorable 31-month follow-up period.

Chronic intestinal ischaemia: diagnosis

Chronic intestinal ischaemia is a relatively rare but very important clinical entity, which is caused by a reduction in the splanchnic blood flow, most often because of atherosclerosis. Intestinal angina is postprandial abdominal pain developing when the genuine and collateral vessels no longer are able to accommodate the postprandial increasing demand from the gastrointestinal tract and the liver. In addition, the clinical picture very often includes sitophobia and weight loss. In daily clinical practice, conventional angiography is considered as the gold standard, but ultra sonography, computerized tomography and magnetic resonance angiography are gaining momentum when investigating for chronic intestinal ischaemia. These methods depend on imaging of the stenotic vessels not taking into consideration the possibility of sufficient splanchnic perfusion in spite of severely stenotic or occluded vessels. Only a few papers address the physiological consequence of stenotic or occluded vessels - the lack of postprandial increase in splanchnic blood flow.

Update in management of mesenteric ischemia

Mesenteric ischemia disorders are precipitated by a circulation insufficiency event that deprives one or several abdominal organs of adequate respiration to meet metabolic demands. Although mesenteric ischemia occurs infrequently, the mortality rate is from 60% to 100%, depending on the source of obstruction. The successful outcome is dependent upon a high index of suspicion and prompt management. We briefly review the pathophysiology and presentation of the various ischemic entities and review the current state of the art in diagnosis and treatment. Despite advances in both diagnosis and treatment, prompt diagnosis and supportive care remain critical for successful outcome. New imaging techniques, endovascular therapy and emerging research may improve our approach to this deadly condition.

Ultrasound evaluation of abdominal aortic and iliac aneurysms and mesenteric ischemia

The role of US in imaging of the abdominal vasculature has broadened over recent years. Long considered the modality of choice in the detection of AAA, its use has expanded to diagnosing and monitoring IAAs and PAAs, screening for mesenteric ischemia, and posttreatment monitoring of endovascular stents.

Color duplex ultrasonography of the superior mesenteric artery after placement of endografts with suprarenal stents

After endovascular repair of abdominal aortic aneurysm with endografts with suprarenal stents, the proximal uncovered stent may cross the origin of the superior mesenteric artery. Effects on splanchnic circulation are unknown and may include development of stenosis at the vicinity of the stent. The criteria of high-grade superior mesenteric artery stenosis using color duplex ultrasonography have been previously reported. The purpose of this study is to examine the incidence of high-grade superior mesenteric artery stenosis in patients with endografts with suprarenal stents using color duplex ultrasonography. Candidates for the study were patients who had placement of an aortic endograft with a suprarenal stent and were able to undergo ultrasonography of the superior mesenteric artery. After reviewing computed tomography scans, patients who had the origin of the superior mesenteric artery crossed by the suprarenal stent underwent color duplex ultrasonography of this vessel. Presence of turbulence or narrowing of the superior mesenteric artery, or a peak systolic velocity greater than 2.75 m/sec, or an end-diastolic velocity greater than 0.45 m/sec were considered significant for the presence of high-grade superior mesenteric artery stenosis. There were 24 patients (21 males, three females), median age 71 years (range, 59-83). The suprarenal stent was crossing the superior mesenteric artery in 17 of 24 patients (71%). Color duplex ultrasound was technically successful in 13 of 17 (76%). The test was performed after a median follow-up of 9 months (range, 3 days to 34 months). No patient had evidence of turbulence or narrowing of the superior mesenteric artery during ultrasonography. The median peak systolic velocity was 0.92 m/sec (range, 0.53-1.21 m/sec). No patient had peak systolic velocity greater than 2.75 m/sec. The median end-diastolic velocity was 0.10 m/sec (range, 0.09-0.14 m/sec). No patient had end-diastolic velocity greater than 0.45 m/sec. Color duplex ultrasonography did not demonstrate the presence of high-grade superior mesenteric artery stenosis during early follow-up of patients with endografts with suprarenal stents. Longer follow-up of larger series of patients is needed to determine the long-term effects of suprarenal stents on splanchnic circulation.

Contrast enhanced duplex ultrasound imaging of the mesenteric arteries

Duplex ultrasound of the visceral arteries is a technically challenging procedure. We examined the clinical usefulness of perflutren intravenous ultrasound contrast to improve the diagnostic accuracy of such studies. Seventeen patients were prospectively studied. A color duplex imaging study of the visceral vasculature was performed with and without the contrast agent. Vessels were imaged and peak systolic velocity and Doppler waveforms of the aorta, celiac artery, superior mesenteric artery, and the inferior mesenteric artery were examined. These results were independently compared to those of contrast angiography. From this analysis we concluded contrast-enhanced duplex imaging of the mesenteric arteries is safe but not routinely required when performed by an experienced sonographer. Ultrasound contrast may be helpful in difficult patients when the vessels are not initially successfully visualized.

Chronic splanchnic ischaemia

Chronic splanchnic ischaemia is a relatively unusual clinical entity consisting of pain and/or weight loss and caused by chronic splanchnic disease (i.e. stenosis and/or occlusion of the coeliac and superior mesenteric artery). The occlusive disease is usually caused by atherosclerosis and is in itself not rare in older individuals. Extensive collateral circulation can develop between the three splanchnic arteries and may compensate for the decreased splanchnic perfusion over time. The pathophysiology of chronic splanchnic ischaemia has still not been completely elucidated.A reliable diagnosis of chronic splanchnic ischaemia, based on a proven causal relationship between the occlusive disease and the symptoms, can be very difficult. Traditionally, tests for evaluating the haemodynamic consequences of the vascular stenoses were not available. Important improvements in establishing a more reliable diagnosis have been achieved with duplex ultrasound and magnetic resonance evaluation of the splanchnic circulation. Tonometry is another promising functional test that may prove useful not only for gaining greater insight into the pathophysiology of chronic splanchnic ischaemia but also for the clinical evaluation of this syndrome. The natural history of chronic splanchnic disease suggests that progressive disease may result in acute mesenteric ischaemia. Surgical reconstruction of the coeliac and/or the superior mesenteric artery is the therapeutic standard with excellent short and long-term results. Satisfactory early results using angioplasty with or without stent suggest that this type of intervention may relieve symptoms in selected patients with a higher surgical risk.

Duplex ultrasound for assessment of superior mesenteric artery blood flow

Duplex ultrasound (DU) is recognised as a valuable tool for the assessment of blood flow in many vascular territories. The application of this technique to the superior mesenteric artery (SMA) has increased rapidly throughout the last decade. The purpose of this review is to collate currently available information on the utility of SMA DU, both in terms of research and clinical practice. Research investigations have revealed low intra- and interobserver variability in the estimation of Doppler variables, while reliable evaluation of B-mode dimensions requires repeated measurements. SMA blood flow velocity has been found to be dependent upon changes in central haemodynamics and in peripheral resistance, which was documented in studies with hypotension, medication and post-prandially. Food intake induces mesenteric vasorelaxation reflected by a 10-fold increase in the diastolic velocity. This feature has been utilised in studies on mesenteric physiology, which confirmed parasympathetic activity during hypovolaemia, and showed that exercise increases splanchnic resistance and reduces its blood flow following a 50% reduction in the hepato-splenic and a 25% reduction in the mesenteric blood flow. Clinical studies have documented high sensitivity and specificity of DU in detection of disease in splanchnic arteries. Diastolic velocity was found to be the most accurate indicator of SMA stenosis, while an absent Doppler signal from a well visualised vessel has been found to be a reliable predictor of occlusion. The high predictive value of DU in the detection of mesenteric artery disease, together with its simplicity and non-invasiveness, suggests that DU should take precedence over arteriography in both clinical practice and laboratory investigations.

The impact of biochemical methods for single muscle fibre analysis

Biochemical methods for single muscle fibre analysis provide sensitive measures for elucidating muscle fibre heterogeneity. The understanding of the complexity of skeletal muscle fibres, initially based on qualitative histochemistry and immunohistochemistry, has been greatly expanded by quantitative micromethods, such as microphotometry and microbiochemical assays. Assessment of metabolic enzyme activity levels has revealed pronounced scattering within and between different fibre types and has highlighted the use of specific enzyme activity ratios as discriminative measures. With the exception of type I fibres, metabolic properties are loosely coupled with molecular properties of the myofibrillar apparatus. As such, myosin heavy chain (MHC) isoforms appear to be the best choice for fibre type delineation. Among the two available methods for MHC-based fibre type distinction, single fibre electrophoresis appears to be superior to immunohistochemistry. The electrophoretic separation of MHC isoforms in single fibres is quantitative and, as opposed to immunohistochemistry, yields important information on MHC isoform proportions in hybrid fibres. Histochemical staining for myofibrillar ATPase activity can, thus, be correlated in most cases with specific MHC isoform profiles. Single fibre studies have demonstrated a relationship between ATP phosphorylation potential and MHC isoform complement. This relationship corresponds to different tension costs and provides an additional rationale for the MHC-based fibre type diversity and transitions. The combination of reverse transcriptase (RT) with polymerase chain reaction (PCR) has proved to be a highly sensitive tool and has extended single fibre analysis to the level of MHC mRNA isoforms. Application of RT-PCR techniques to single fibre fragments identified by their MHC protein isoform profile, provides insights at two levels of expression and, thus, has extended our knowledge on the plasticity of muscle and the dynamical state of muscle fibres.