T.M. Buckenham

Renal artery stenosis: A common and important problem in patients with peripheral vascular disease

OBJECTIVE To study the prevalence, severity, vascular risk factors, and clinical implications of renal artery stenosis in patients with peripheral vascular disease. DESIGN Cross-sectional study of consecutive patients who were electively referred from the department of vascular surgery for lower limb digital subtraction angiography. SETTING St. Georges Hospital, London, United Kingdom. SUBJECTS One hundred twenty-seven patients presenting with intermittent claudication or lower limb ischemic ulceration. MAIN OUTCOME MEASURES Prevalence and clinical importance of renal artery stenosis in patients with peripheral vascular disease adjusted for the confounding effects of age and hypertension. RESULTS Of the 127 patients, 57 (44.9%) had renal artery disease, of whom 22 (17.3%) had mild disease, 20 (15.7%) had severe disease, and 15 (11.8%) had bilateral renal artery stenosis. There was a significant positive relationship between the presence of renal artery stenosis and the severity of peripheral vascular disease (p = 0.00015). The risk of having renal artery stenosis was nearly four times greater in those with three to four vessels affected and nearly seven times greater in those with five or more vessels affected as compared with those with a milder degree of peripheral vascular disease (one or two vessels affected). This association persisted when the confounding effect of age and hypertension was accounted for. Six patients (31.6%) with renal artery stenosis who underwent revascularization for peripheral vascular disease died during the early postoperative period of cardiac or renal complications. None of the patients with normal renal arteries who had similar surgery developed postoperative complications (p = 0.005). CONCLUSIONS Renal artery stenosis is a common independent feature in patients with peripheral vascular disease, and its prevalence increases with the increasing severity of the peripheral vascular disease. The postoperative risk following revascularization for peripheral vascular disease appears to be greater in those patients with renal artery stenosis. All patients studied with digital subtraction angiography for peripheral vascular disease should have an aortic flush performed to image the renal arteries. This information may be used to identify those patients likely to develop postoperative complications during peripheral revascularization.

Carotid angioplasty. Detection of embolic signals during and after the procedure.

Carotid angioplasty may offer an effective treatment for carotid stenosis, but there has been concern about the incidence and clinical consequences of distal embolization. Transcranial Doppler monitoring in carotid endarterectomy has demonstrated embolic signals during this procedure. We used this technique in patients undergoing carotid angioplasty. Methods Transcranial Doppler ultrasound was used to monitor for embolic signals in the ipsilateral middle cerebral artery before and during 10 technically successful carotid angioplasties and at various standardized times in the following month. Results In the month before angioplasty asymptomatic embolic signals were detected in 3 of 10 patients. During angioplasty multiple embolic signals were detected immediately after balloon inflation in 9 of 10 subjects. A minor ipsilateral cerebral ischemic event occurred in 1 of these 9, but the other 8 were asymptomatic. Embolic signals were common immediately after the procedure and intra-arterial femoral catheter removal (8 of 10 subjects) but thereafter became less frequent and were present in 1 of 5 at 4 hours, 2 of 10 at 48 hours, 1 of 6 at 7 days, and 1 of 10 at 1 month. Conclusions Embolization at the time of carotid angioplasty is very common but usually asymptomatic; monitoring by means of Doppler ultrasound will allow the effectiveness of measures to reduce this embolization to be studied. Late embolization occurs in a minority of patients and may account for the small but significant risk of delayed stroke. Doppler monitoring may allow identification of patients at risk and assessment of the effectiveness of prophylactic therapy.

Microscopic air embolism during cerebral angiography and strategies for its avoidance

Cerebral angiography is associated with a risk of neurological complications and air embolism may contribute towards this risk. To test this hypothesis, transcranial doppler ultrasonography was used to monitor the presence of air emboli in the middle cerebral arteries of 7 patients undergoing cerebral angiography. Doppler signals consistent with numerous air emboli were noted during each injection of radiographic contrast. This phenomenon was studied further in sheep. Radiographic contrast medium was injected into the carotid artery while a major carotid branch was insonated transorbitally. Embolic signals similar to those seen in patients were noted. Air was introduced at two points. First, at the time of drawing up the contrast into the syringe, especially with more viscous media. Standing the media before injection resulted in a highly significant reduction of air embolism, reducing the total mean duration of emboli from 1.32 (SD 0.60) s after immediate injection to 0.04 (0.05) s after ten minutes standing for iohexol 340 mg/mL (p < 0.001). Second, air was introduced at the time of injection, possibly by the formation of cavitation bubbles under pressure. This occurred most prominently with the less viscous contrast media and with saline, and was significantly reduced by slow injection (mean duration of emboli for saline 2.85 [2.43] s with fast injection compared with 0.32 [0.37] s with slow injection, p = 0.004). Air embolism may contribute towards neurological dysfunction after angiography. Measures should be taken to reduce this by allowing contrast media to stand prior to injection, and by flushing catheters with saline injected slowly.

Non-invasive screening for renal artery stenosis with ultrasound contrast enhancement.

Objective Our aim was to evaluate duplex ultrasound imaging in the identification of renal artery stenosis using a new technique to enhance the recorded Doppler signal. Design Colour Doppler studies of interlobar renal arteries were performed before and after enhancement using an intravenous contrast of galactose microparticle suspension containing microbubbles (Levovist, Schering) in patients with angiographically confirmed renal artery stenosis. Setting Blood Pressure Unit, St. Georges Hospital Medical School, and Department of Radiology, The Middlesex Hospital, London, UK. Participants Twenty-one consecutive hypertensive patients in whom the diagnosis of renal artery stenosis was made on digital subtraction angiography. Main outcome measures The diagnosis of haemodynamically significant renal artery stenosis (≥60% on angiography). Results With Levovist, there was a 20 db increase in the Doppler intensity and, as a result, intrarenal signals were much more clearly delineated and distinct spectral waveforms were obtained from all but one kidney, which was occluded. Significant associations were found between the degree of stenosis (as assessed by angiography) and the following Doppler parameters: diastolic velocity (F=7.6; P < 0.01), acceleration time (F=33.5, < 0.0001), peak systolic velocity (F=37.7, P < 0.0001) and acceleration (F=60.0; P < 0.0001). Without enhancement, there were five false-positive and two false-negative examinations (sensitivity 85%; specificity 79%) using the acceleration cut-off value of 3.5 m/s2 to identify haemodynamically significant renal artery stenosis (≥60% on angiography). After contrast enhancement, there were only three false-positive and one false-negative examinations (sensitivity 94% and specificity of 88%) using the acceleration cut-off value of 3.75 m/s2 and the examination time was reduced by approximately half (sensitivity and specificity of 90% using the acceleration cut-off value of 3.5 m/s2). Conclusions Our results suggest that renal duplex scanning using contrast enhancement is a promising new non-invasive technique in screening patients with suspected renal artery stenosis. Contrast enhancement produces more reproducible spectral waveforms, improves accuracy and halves the examination time.

Transbrachial Arteriography: Indications and Complications

PURPOSE to retrospectively evaluate brachial artery puncture at the antecubital fossa with regard to the indications for and complications arising from the procedure. PATIENTS AND METHODS Sixty-two cumulative brachial artery punctures in fifty-three patients over a 5-year-period were retrospectively studies. RESULTS In the majority of cases the brachial approach was utilised in order to avoid groin puncture in patients with absent femoral pulses or recent graft surgery. Occasionally it was performed as a more direct method of assessing upper limb arterial anatomy. Catheter sizes ranged from 3F to 8F. Fifty-one (82%) of the procedures were diagnostic and 11 (18%) were interventional. Glyceryl trinitrate was routinely administered. The overall incidence of complications was low (8%) and included haematoma and arterial spasm. None required surgical intervention and all resolved without permanent sequelae. CONCLUSION Brachial artery puncture at the antecubital fossa is a suitable site of access for both diagnostic and interventional procedures. Potential limitations are the long distance from puncture site to that of intervention and damage to the brachial artery can result in upper limb ischaemia. Percutaneous brachial artery puncture at the antecubital fossa is, however, a low-risk alternative to either intravenous digital subtraction angiography or axillary artery puncture in patients in whom the femoral approach is contraindicated.

Improvement in Cerebral Hemodynamics After Carotid Angioplasty

BACKGROUND AND PURPOSE Carotid percutaneous transluminal angioplasty ( PTA) may offer an alternative treatment to carotid endarterectomy. However, in contrast to carotid endarterectomy, which has been shown to normalize impaired cerebral hemodynamics, the effects of carotid PTA are unknown. Therefore, we prospectively studied the effect of carotid PTA on both perioperative and postoperative cerebral hemodynamics. METHODS Eleven patients undergoing carotid PTA for symptomatic carotid artery stenosis were prospectively studied. Transcranial Doppler recordings from the ipsilateral middle cerebral artery (MCA) were performed during the procedure. In addition, MCA blood flow velocity and CO2 reactivity were determined before PTA and at 2 days, 1 month, and 6 months after procedure. The results were compared with those in 11 similar patients undergoing carotid endarterectomy in whom measurements were performed before and 1 month after the operation. RESULTS During carotid PTA, in 2 of 11 patients during passage of the balloon catheter through the stenosis, MCA blood flow velocity fell transiently. In 6 of 11 patients there was a reduction in flow velocity (>50%) during balloon deflation, but this lasted only a few seconds. After the procedure there was a significant improvement in ipsilateral hypercapnic reactivity: preoperative value, 59.8+/-42.2% (mean+/-SD); 2 days, 77.9+/-31.4%; 1 month, 88.7+/-45.0%; 6 months, 89.8+/-33.9%; and (ANOVA P=.003) preoperative value versus 1 month, P<.02; versus 6 months, P<.02. In all cases in which reactivity was significantly impaired preoperatively, it returned to the normal range. Pulsatility index also increased significantly: preoperative value, 0.827+/-0.251 (mean+/-SD); 2 days, 0.992+/-0.262 (P=.002). Contralateral MCA hypercapnic reactivity also improved after carotid PTA. There was a similar improvement in ipsilateral hypercapnic reactivity after carotid endarterectomy. CONCLUSIONS Carotid PTA results in a normalization of impaired hemodynamics, as assessed by CO2 reactivity. The degree of improvement is similar to that seen after carotid endarterectomy.

Per Oral Balloon Sialoplasty: Results in the Treatment of Salivary Duct Stenosis

AbstractPurpose: To evaluate the results of balloon dilatation of salivary duct stenosis and to discuss the technique and its limitations. Methods: Balloon dilatation of 30 salivary duct stenoses (24 parotid, 6 submandibular) was carried out in 29 patients over a 5-year period. Duct dilatation was performed with a 3-mm-diameter balloon on a 0.035-inch wire passed into the salivary duct under fluoroscopic guidance. The follow-up period ranged from 1 month to 5 years. Results: In 25 patients balloon dilatation was technically successful in 26 of 30 ducts (87%). Ninety-six percent of parotid duct dilatations and 50% of submandibular duct dilatations were technically successful. Early clinical follow-up after parotid duct dilatation showed that 57% of patients were asymptomatic, 39% showed an improvement in symptoms, and 4% showed no improvement in symptoms. Following technically successful submandibular duct dilatation (3 cases), 1 patient showed complete resolution of symptoms and 1 showed no change in symptoms. No follow-up was available for 1 patient. No significant complications were seen. The longer-term results are presented. Conclusion: Balloon dilatation of salivary duct stenosis is a simple, safe, and clinically effective method of relieving obstructive symptoms of parotid duct stenosis.

The use of the Angio-Seal haemostatic puncture closure device in high risk patients

The use of the Angio-Seal haemostatic puncture closure device in 45 patients considered to be at increased risk of puncture site complications is described. Successful device deployment occurred in 44 of 50 arteries (88%). Two major complications were associated with, but not necessarily caused by, the Angio-Seal device. Four minor complications were observed. In a subset of 23 patients well enough to mobilize early after their procedure, 17 did so at an average of 2.6 h as opposed to the routine 12-18 h for patients after a procedure involving a 6-8F sheath. Once the initial learning curve has been overcome, the Angio-Seal device is a simple and successful method of achieving arterial haemostasis following catheterization and is associated with a low risk of complications. At present we would recommend its use for high risk patients only, as manual compression is effective in the majority of routine cases.

Percutaneous transluminal angioplasty by a retrograde subintimal transpopliteal approach

We report three cases of femoropopliteal occlusive disease which were successfully recanalized subintimally and retrogradely via the popliteal artery. The merits and limitations of this approach are discussed.

Accelerated thrombolysis using pulsed intra-thrombus recombinant human tissue type plasminogen activator (rt-PA)

The efficacy of regional thrombolysis for treating leg ischaemia is well established, but the duration of infusion and the frequent complications remain major disadvantages. By delivering recombinant human tissue type plasminogen activator (rt-PA) as pulsed intra-thrombus 5-mg aliquots combined with catheter manipulation to maintain an intra-thrombus location, the average time taken to achieve thrombolysis in 20 consecutive patients with infra-aortic occlusions was 109 min. Immediate thrombolysis was achieved in every case. Pulsed delivery of high dose rt-PA significantly accelerates thrombolysis, decreases dose and reduces costs.