Doppler ultrasound monitoring for detection of microembolic signals in peripheral arteries.

OBJECTIVE: to use Doppler ultrasound to detect peripheral microemboluation. METHODS: standard Transcranial Doppler equipment was used to peripheral detect peripheral embolic high intensity transient signals (HITSs) in a pig model following injection of microparticles and atheroma, and in 23 patients who underwent open repair of an abdominal aortic aneurysm (AAA), six patients with blue toe syndrome and 10 age matched healthy subjects. RESULTS: the pig study showed increasing signal intensity with particle size. Particles of 100 (n=24), 200 (n=17), and 400 microm (n=31) elicited 14, 25, 33 dB signals, respectively (p<0.05). During AAA surgery, the intensity (median) of HITSs before clamping (n=226) and after declamping (n=1216) were 14, and 20dB, respectively (p<0.001). Quite a few HITSs were detected after surgery. In patients with blue toe syndrome, a total of 63 HITSs could be detected, and the frequency of HITSs (median: 5.72/30min) was significantly higher than that in patients with AAA before surgery (0.065/30min) (p<0.001).CONCLUSIONS: Doppler ultrasound technique may be a clinically useful test to guide the treatment of patients at risk of distal atheroembolic events.     

Continuous noninvasive monitoring of cardiac output with esophageal Doppler ultrasound during cardiac surgery

Esophageal Doppler ultrasonography offers a continuous and noninvasive alternative to standard thermodilution cardiac output monitoring. A total of 372 simultaneous measurements of Doppler and thermodilution cardiac output were compared in 16 patients undergoing cardiac surgery. In addition, echocardiographic aortic diameter measurement, necessary for Doppler calibration, was compared with direct surgical measurement in 23 patients. Echocardiographic aortic measurement was often time consuming and correlated poorly (r = 0.31) with surgical measurement. On the other hand, Doppler cardiac output was determined easily and accurately tracked thermodilution cardiac output (R2 = 0.95, common slope coefficient 1.050, by multiple linear regression). Furthermore, Doppler cardiac output was more reproducible, showing less short-term variability than thermodilution cardiac output. The esophageal Doppler technique allows cardiac output monitoring in patients for whom invasive monitoring is not warranted.     

Carotid endarterectomy: a retrospective analysis. Microendarterectomy and transcranial Doppler ultrasound monitoring

BACKGROUND: Analyses of the results obtained following our protocol for the surgical therapy of carotid artery stenosis is the aim of this study. METHODS: Ninety-one procedures were performed on 84 patients by the same surgical team. Indications for carotid endarterectomy (CEA) were 50-70% internal carotid artery (ICA) stenosis in 8% of the patients (100% symptomatic), 70-90% stenosis in 67% (64% symptomatic) and 90-99% ICA stenosis in 25% of our patients (33% symptomatic). Carotid shunt during arterial cross-clamp was only used in 4 cases (4.4%) following trans-cranial Doppler ultrasound (TCD) intraoperative monitoring findings. Operative microscope or surgical loupes were used for the complete removal of atheroma and the direct suture of the arteriotomy. Heparin was only antagonised in selected cases. RESULTS: No mortality and no permanent deficit related to ischemic events were present in our patients; a transient neurological deficit occurred in 1 case (1.1%). Two patients died (2.2%): 1 due to myocardial infarction and the second one to bronchopneumonia. Transient peripheral nerve deficits were noted in 2 cases. CONCLUSIONS: In order to reduce to a minimum ischemic risks during CEA, our preliminary experience advises microsurgical technique for the complete removal of the atheroma and suture, TCD evaluation of collateral reserve during cross-clamping, and the use of randomised multicenter studies guidelines for the selection of patients. More attention must also be given to postoperative care, since hemodynamic instability represents the main risk for our patients. Overnight intensive care unit (ICU) surveillance in all patients may help to avoid fatal complications.     

Effect and outcome of balloon angioplasty and stenting of the iliac arteries evaluated by intravascular ultrasound.

OBJECTIVES: To document the mechanism of percutaneous transluminal angioplasty (PTA) and stenting of the iliac arteries, and to relate the effect to patency. MATERIALS AND METHODS: Thirty-seven stenotic iliac arteries were examined by intravascular ultrasound (IVUS) and arteriography before and after PTA, and after stent deployment (n = 16). The patients were followed prospectively by duplex scanning at 3, 6, 12, 18 and 24 months after the intervention. RESULTS: The effect of PTA was established by both compression and stretching with the major contribution arising from stretching. There were differences in the effect of PTA dependent on plaque morphology: in homogeneous eccentric lesions, stretching contributed significantly more than compression to the luminal gain, while stretching and compression contributed equally in concentric or heterogeneous plaques. Stenting of the arteries had no effect on the free luminal area as measured by IVUS. The primary 1-year patency rate was 72%. The patency was related to the free luminal area and diameter and the heterogenicity of the plaque as evaluated by IVUS. The arteriographic measurements did not have any predictive value. CONCLUSION: IVUS was able to document the effect of PTA and stenting in the iliac arteries, and predict the outcome. The luminal gain and reduction in degree of stenosis seemed to be accomplished primarily by stretching of the arteries and to a lesser extent by plaque compression. Stenting did not change the IVUS measurements. Patency was related to the size of the free lumen and the heterogenicity of the plaque.     

Identification of microemboli during haemodialysis using Doppler ultrasound.

BACKGROUND: Doppler ultrasound methods were used during haemodialysis sessions for the detection of microemboli and determination of their origin. METHODS: A 2-MHz ultrasound probe (Multidop X(4) DWL((TM))) was used to assess the number of microembolic signals (MES) in the subclavian vein downstream from the arteriovenous fistula before the dialysis session and over two periods of 15 min at the beginning and end of haemodialysis sessions in 25 patients without previous cardiovascular disease. A similar probe was used during in vitro studies to detect MES at different sites in the dialysis machine (before and downstream from the blood pump, and before and downstream from the air trap). RESULTS: No MES were detected during in vivo studies before haemodialysis sessions. MES were registered in all patients (100%) at the beginning and end of the haemodialysis procedure at an average of 12.7+/-9 and 16. 7+/-11.5 signals/min respectively. The average intensity of MES was 19.2+/-5.0 dB and 19.4+/-3.9 dB respectively. No MES were detected on the arterial line during in vitro studies. In contrast, 19+/-6 MES/min were detected after the blood pump, 13+/-4.2 before the air trap, and 16.5+/-5.5 thereafter. CONCLUSIONS: In all patients, MES were recorded during haemodialysis sessions in the drainage vein from arteriovenous fistulae. The results of in vitro studies indicate that MES are formed by the blood pump of the haemodialysis machine. The intensity of the MES suggests that they correspond to synthetic particles or microbubbles, which are not detected by the air trap. The final destination of these microbubbles will be assessed in further studies.     

彩色多普勒超声诊断周围型肝内胆管细胞癌的价值

目的 探讨彩色多普勒超声对周围型肝内胆管细胞癌的诊断价值.方法 回顾性分析95例经病理证实的周围型肝内胆管细胞癌,总结其彩色多普勒超声特征.结果 总共102个病灶,大小范围为20 mm×20 mm～130 mm×100 mm.灰阶图像上大部分病灶表现为回声不均匀(75个,73.5％)、边界模糊(70个,68.6％)、分叶状(55个,53.9％).彩色多普勒超声示大部分病灶能检测到血流(75个,73.5％),以簇状、短线状及彩点状血流为主,其中大部分血流的阻力指数大于0.6(65个,86.7％).102个病灶中,见条索样高回声的有37个(36.3％),后方回声出现轻度衰减的有29个(28.4％),出现“脐凹”现象的有22个(21.6％).超声诊断的符合率为84.2％(80/95).结论 周围型肝内胆管细胞癌的彩色多普勒超声表现具有一定的特征,充分认识其声像图特征可提高超声诊断的准确率.     

Intravascular ultrasound scanning improves long-term patency of iliac lesions treated with balloon angioplasty and primary stenting

PURPOSE: Underdeployment of an intravascular stent has been identified as a cause of restenosis or occlusion of a treated arterial lesion. Intravascular ultrasound (IVUS) has been shown to initially improve the anatomic and clinical stenting. The purpose of this study was to determine whether the use of IVUS increased long-term patency of this intervention. METHODS: Between March 1992 and October 1995, 71 limbs (52 patients) with symptomatic aortoiliac occlusive disease underwent balloon angioplasty with primary stenting. IVUS and arteriography were used in 49 limbs (36 patients) to evaluate stent deployment. Arteriography alone was used in 22 limbs (16 patients) to evaluate stent deployment. Patients were captured prospectively in a vascular registry and retrospectively reviewed. RESULTS: Mean age of patients treated with IVUS was 61.1 plus minus 9.0 years (range, 38-85) versus 70.0 plus minus 10.1 years (range, 57-87) in patients treated without IVUS (P <.01). There was no difference between the groups with respect to preoperative comorbidities, ankle-brachial indices, or number of stents per limb. Mean follow-up for IVUS patients was 62.1 plus minus 7.3 months (range, 15-81) and 57.9 plus minus 8.7 months (range, 8-80) for patients treated without IVUS (P = not significant). In 40% (20/49) of limbs, IVUS demonstrated inadequate stent deployment at the time of the original procedure. Kaplan-Meier 3- and 6-year primary patency estimates were 100% and 100% in the IVUS group and 82% and 69%, respectively, in limbs treated without IVUS (P <.001). There have been no secondary procedures performed in limbs treated with IVUS and a 23% (5/22) secondary intervention rate in the non-IVUS group (P <.05). Overall Kaplan-Meier survival estimates at 3 and 6 years for all patients were 84% and 67%, respectively. CONCLUSION: Balloon angioplasty and primary stenting of symptomatic aortoiliac occlusive lesions is a durable treatment option. Long-term follow-up of treated patients shows outcomes that are comparable with direct surgical intervention. IVUS significantly improved the long-term patency of iliac arterial lesions treated with balloon angioplasty and stenting by defining the appropriate angioplasty diameter endpoint and adequacy of stent deployment.     

An implanted ultrasound Doppler probe for microvascular monitoring: an experimental study

An experimental investigation is presented into the use of pulsed ultrasound Doppler flowmetry with a percutaneously implanted probe as a monitor of microvascular anastomotic patency. The method accurately indicated and distinguished between experimental arterial and venous occlusion in epigastric island flaps. In free flaps it had advantages over manipulative, intraoperative tests of anastomotic patency and was a reliable post-operative monitor of flap circulation in the experimental model. The technique appears to have great potential as a post-operative monitor for free flaps, including those without a visible surface.     

Assessment of colonic ischemia during aortic surgery by Doppler ultrasound.

Colonic ischemia, related to division of the inferior mesenteric artery during aortic surgery, can be a significant cause of postoperative mortality. Operative determination of collateral mesenteric blood flow during temporary occlusion of the inferior mesenteric artery by use of the Doppler ultrasound device was evaluated in 25 patients undergoing aortic reconstructive vascular procedures. In five patients, the evaluation confirmed arteriographic evidence of an occluded inferior mesenteric artery; however, collateral flow was audible at the base of the large bowel mesentery and serosal surface of the left colon. In the other 20 patients with patent inferior mesenteric arteries, temporary occlusion of the artery resulted in persistent audible collateral flow in eighteen. However, in the remaining two patients, temporary arterial occlusion resulted in loss of audible Doppler flow signals over the base of the mesentery and serosa of the left colon. Maintaining patency of the inferior mesenteric artery by proper placement of the aortic graft in one patient and reimplantation of the artery into the prosthesis in another resulted in a return of Doppler flow over the left colon. All patients did well post operatively. Our data suggest that the presence of audible Doppler flow over the base of the large bowel mesentery and serosal surface of the left colon may correlate with viability of the colon postoperatively. We recommend routine use of the Doppler ultrasound device to determine adequacy of collateral mesenteric blood flow in patients undergoing aortic reconstructive vascular procedures.     

Doppler ultrasound in aortic dissections: a study of cephalic and peripheral arteries

We investigated the role of continuous-wave Doppler ultrasound in predicting the presence of an aortic dissection prospectively in 28 patients whose diagnosis was confirmed either by arteriography or surgery (26 cases) or at autopsy (two cases). We hypothesized that dissections, by creating two channels for flow, would produce velocity disturbances detectable in accessible arteries such as the carotid, brachial, and femoral arteries. Of the 28 patients, 20 had Type I, two Type II, and six Type III dissections. Two abnormalities of the Doppler signals were found: in 18 of Type I dissections, notching was found in the systolic upslope of the velocity tracing from those arteries that were either involved in or distal to the dissection sites. Notching was much less frequent for Type II and III dissections: only one patient with Type II and two patients with Type III dissections showed notching. In addition diastolic backflow with marked aortic valvular insufficiency was present. Notching in brachiocephalic artery continuous-wave Doppler signals appears to have a high positive predictive value for Type I dissections.     

Septic endarteritis and fatal iliac wall rupture after endovascular stenting of the common iliac artery.

A 52-year-old female with arterial occlusive disease underwent an uneventful percutaneous transluminal angioplasty and placement of a vascular metallic stent in the left common iliac artery. Ten days later she presented with clinical symptoms of septic endarteritis. Shortly after re-admittance, an emergency laparotomy had to be performed because of an acute retroperitoneal bleeding. Rupture of the common iliac artery directly overlaying the penetrating stent was found but control of haemorrhage was of no avail. In this report of a case, septic endarteritis following placement of a vascular metallic stent preceded fatal rupture of the common iliac artery. This up to now unknown constellation requires surgical intervention without undue delay.     

Cerebral microembolization during pediatric scoliosis surgery: a transcranial doppler study.

SUMMARY: The goal of this study was to identify cerebral microemboli during scoliosis surgery and their potential relationship with visual alterations. Transcranial Doppler identified high-intensity transient signals (HITS) during surgery in both middle cerebral arteries, and ophthalmologic examination assessed their potential effects on the visual system. Thirteen children (age 13-17 years) undergoing surgery for scoliosis or kyphosis with spine curvature >45 degrees were studied. HITS were identified in 92%. Eleven patients had a total count of <15 HITS, but in the remaining two the count was unexpectedly high (63 and 265 HITS). Echocardiography in these two patients indicated the presence of an atrial right-to-left shunt. Uneventful preoperative and postoperative visual function was found in 11 patients. One patient had preoperative blindness and in another ophthalmologic complications developed not related to microembolization. Scoliosis surgery is frequently associated with low counts of cerebral microemboli. It appears that such low embolic counts have no effects on postoperative visual function as determined clinically. Some patients may show high rates of microemboli, which may be related to the presence of right-to-left cardiac shunts. The impact of these signals on brain function remains to be investigated.