Accuracy of MDCT in the determination of supraaortic artery stenosis using DSA as the reference standard

Total arterial revascularization with RIMA-LIMA-Y configuration in patients with left subclavian artery stenosis

BACKGROUND

Subclavian artery stenosis (SAS) occurs in 6% of patients undergoing coronary artery bypass grafting (CABG). Complications such as subclavian-coronary steal are common. Revascularization options in such cases remain debatable.

METHODS

In this case series, all patients with angina, had severe triple vessel disease on angiography. All tests including computed tomography (CT) angiography of neck vessels, were done as part of routine workup for CABG.

RESULTS

The patients, all males, had a mean age of 66.5 years with three of them having hypertension and diabetes. All were ex-smokers with mean ejection fraction (EF) of 60.1%. CT angiography of neck vessels revealed that two patients had moderate to severe while one had severe left SAS and another had severe proximal left internal mammary artery (LIMA) stenosis. Total arterial revascularization was performed, with an average of 3.5 distal grafts. The LIMA graft was employed in a Y graft configuration, anastomosed to in-situ right internal mammary artery (RIMA). All patients had uneventful postoperative stay and were discharged with a mean hospital stay of 3.8 days. There were no postoperative strokes, myocardial infarction, neurological symptoms, or change in EF. At 6-month follow-up, they were asymptomatic and doing well.

CONCLUSION

The RIMA-LIMA-Y configuration can be a safe, viable option in CABG for patients with left SAS. It is challenging, with re-entry and judicious utilization of the length of LIMA being of paramount importance. The importance of CT angiography of neck vessels to detect SAS cannot be under-emphasized.

Application of digital subtraction angiography in canine hindlimb arteriography

OBJECTIVES

Research in the field of lower extremity vascular disease has increased in popularity over the years. To adequately characterize and validate the effectiveness of vascular interventions, in vivo experimentation in large animals is required. Thus, it is necessary to find a method to detect the shape and density of blood vessels in the lower extremities that can evaluate and verify the treatment measures' effectiveness and have high accuracy and repeatability. This study characterized factors that determined both the accuracy and overall value of digital subtraction angiography in lower limb arteriography using a canine animal model.

METHODS

Six beagle dogs were anesthetized and immobilized on the motorized table. The femoral artery was accessed using an indwelling needle. A bolus of contrast agent was injected into the access site, and digital subtraction angiography with bolus chase technology was used to collect contrast images for analysis. At the end of the procedure, the anesthetized dogs were euthanized using an overdose of potassium chloride. After confirming the euthanasia of the dogs, the cadavers were taken to the experimental animal center of Xinjiang Medical University and processed by qualified institutional personnel.

RESULTS

The final arteriographic images of the hind limbs from all six dogs were precise, and the branches of small vessels could be distinguished without any visible artifacts.

CONCLUSIONS

These results suggested that arteriography using digital subtraction angiography could reveal the shape and density of blood vessels in canine animal models. This method has great potential to significantly improve research related to limb ischemia due to its simple and reproducible results.

Coronary Subclavian Steal Syndrome: A Contemporary Review

Coronary subclavian steal syndrome (CSSS) is a rare cause of angina. It occurs in patients with prior coronary artery bypass grafting and, specifically, a left internal mammary artery (LIMA) to left anterior descending artery (LAD) graft and co-existent significant subclavian artery stenosis. In this context, there is retrograde blood flow through the LIMA to LAD graft to supply the subclavian artery beyond the significant stenosis. This potentially occurs at the cost of compromising coronary artery perfusion dependent on the LIMA graft. In this review, we present a case of a middle-aged female who suffered from CSSS and review the literature for the contemporary diagnosis and management of this condition.

Myocardial ischaemia due to subclavian stenosis after coronary artery bypass graft: a case report

Introduction

Subclavian artery stenosis occurs up to 4.6% in patients who are referred for a coronary artery bypass graft (CABG). Subclavian artery stenosis can compromise the blood flow in the ipsilateral mammary artery.

Case presentation

In this case report, we describe a patient with prior history of CABG and peripheral vascular disease, who presented with recurrent chest pain symptoms. Cardiac perfusion imaging using Rubidium-82 positron emission tomography showed extensive ischaemia in the anterior wall. Coronary angiography showed an ipsilateral (left) severe subclavian stenosis, while there was no significant stenosis in the bypass grafts. Patient’s symptoms resolved after percutaneous intervention of the left subclavian artery.

Discussion

The presence of subclavian artery stenosis can result in myocardial ischaemia after prior CABG utilizing the internal mammary artery. A history of peripheral vascular disease and a blood pressure difference between the upper extremities greater than 15 mmHg are clinical predictors of subclavian artery stenosis. Percutaneous angioplasty and stenting is considered the first-line treatment for subclavian artery stenosis. Surgical management should be considered after failure of endovascular treatment in low-surgical-risk patients.

Review of coronary subclavian steal syndrome

The clinical benefits of using the left internal mammary artery (LIMA) to bypass the left anterior descending artery are well established making it the most frequently used conduit for coronary artery bypass surgery (CABG). Coronary subclavian steal syndrome (CSSS) occurs during left arm exertion when (1) the LIMA is used during bypass surgery and (2) there is a high grade (≥75%) left subclavian artery stenosis or occlusion proximal to the ostia of the LIMA resulting in "stealing" of the myocardial blood supply via retrograde flow up the LIMA graft to maintain left upper extremity perfusion. Although CSSS was once thought to be a rare phenomenon, its prevalence has been underestimated and is becoming increasingly recognized as a serious threat to the success of CABG. Current guidelines are lacking on recommendations for screening of subclavian artery stenosis (SAS) pre- and post-CABG. We hope to provide an algorithm for SAS screening to prevent CSSS in internal mammary artery bypass recipients and review treatment options in the percutaneous era.

Cerebral CT angiography and CT perfusion in acute stroke detection: a systematic review of diagnostic value

The purpose of this study was to analyse the diagnostic value of cerebral CT angiography (CTA) and CT perfusion (CTP) examinations in the detection of acute stroke based on a systematic review of the current literature. The review was conducted based on searching of seven databases for articles published between 1993 and 2013. Diagnostic value in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy was analysed from 21 articles which were found to meet selection criteria. The mean sensitivity, specificity, PPV, NPV and accuracy for CTA were significantly higher than those for CTP with 83.2% (95% CI: 57.9-100.0%), 95.0% (95% CI: 74.4-100%), 84.1% (95% CI: 50.0-100%), 97.1 (95% CI: 94.0-100%) and 94.0% (95% CI: 83.0-99.0) versus 69.9% (95% CI: 20.0-97.0%), 87.4 (95% CI: 61.0-100.0%), 76.4% (95% CI: 48.0-95.4%), 78.2% (95% CI: 55.8-93.9%) and 89.8% (95% CI: 75.7-97.1%), respectively. This analysis shows that CTA has high diagnostic value in detecting high degree of cerebral arterial stenosis (>70%) whereas CTP provides high specificity in the detection of ischemia and infarct tissue of brain.

Bidirectional flow in the vertebral artery is not always indicative of the subclavian steal phenomenon

OBJECTIVE

To evaluate the causes of bidirectional flow in the vertebral artery detected by Doppler sonography and its differential diagnosis.

METHODS

Twenty-nine patients with bidirectional flow in the vertebral artery were retrospectively studied. The vertebral artery parameters, including peak antegrade velocity (PAV), peak reversed velocity (PRV), maximum peak velocity (MPV), peak systolic velocity, resistive index (RI), and diameter, were measured. The MPV was defined as the MPV of bidirectional flow regardless of the velocity of antegrade or retrograde flow. To better predict the cause of bidirectional flow, receiver operating characteristic curves were constructed for these parameters, and the best cutoff values were obtained. The cause of bidirectional flow was determined by angiography.

RESULTS

The causes of bidirectional flow were classified as the subclavian steal phenomenon (n = 21) and factors unrelated to the steal phenomenon (n = 8, including a hypoplastic vertebral artery [n = 4] and proximal vertebral artery stenosis and occlusion [n = 4]). Significant differences were observed between the steal phenomenon and non-steal phenomenon groups (P< .05) for MPV, PRV, PAV, target vertebral artery diameter, and contralateral RI. To determine the cause of bidirectional flow, areas under the receiver operating characteristic curves for the different parameters were obtained: 0.929 for MPV, 0.881 for PRV, 0.824 for PAV, 0.753 for target vertebral artery diameter, and 0.845 for contralateral RI. The cutoff value for MPV was 26.1 cm/s, and the accuracy was 93% (27 of 29).

CONCLUSIONS

Bidirectional flow in the vertebral artery is not always indicative of the subclavian steal phenomenon. Measurement of hemodynamic parameters in the vertebral artery, such as MPV, can facilitate determination of the cause of bidirectional flow.