Electron-beam CT scanning for detection of coronary calcification and prediction of coronary heart disease

Electron-beam or ultrafast computerized tomographic (CT) scanning provides a convenient and sensitive means of detecting coronary calcification, which is an early index of atherosclerosis. The procedure has strong negative predictive power for the presence of coronary artery disease, but a limited ability to predict disease severity. However, preliminary indications are that it is as good or better than conventional risk factors in this respect. Although further validation is needed before electron-beam CT can be regarded as an established method of detecting presymptomatic coronary atherosclerosis, the procedure has potential in this context.     

Electron-beam CT: the effect of using a correction function on coronary artery calcium quantitation

The relationships between 4 bacterial and 3 viral antibody titers and morbidity (undifferentiated fever (UF)) and mortality were investigated in recently weaned beef calves. Blood samples from 100 animals that required treatment for UF (Cases) and 100 healthy control animals (Controls) were obtained: upon arrival at the feedlot (Arrival), at the time of selection as a Case or Control (Selection), and at approximately 33 d of the feeding period (Convalescent). Seroconversion to Pasteurella haemolytica antileukotoxin was associated with an increased risk of UF (OR = 2.83); however, seroconversion to bovine herpesvirus-1 G-IV glycoprotein was associated with a decreased risk of UF (OR = 0.43). Higher Arrival bovine viral diarrhea virus antibody titer was associated with a decreased risk of UF (OR = 0.83). Increases in Mycoplasma alkalescens antibody titer after Arrival were associated with an increased risk of UF (OR = 1.10). Higher Arrival Haemophilus somnus antibody titer and increases in Haemophilus somnus antibody titer after Arrival were both associated with a decreased risk of UF (OR = 0.76 and OR = 0.78). The odds of overall mortality (OR = 5.09) and hemophilosis mortality (OR = 11.31) in Cases were significantly (P < 0.05) higher than in the Controls. Higher Arrival bovine herpesvirus-1 antibody titer was associated with an increased risk of mortality (OR = 1.30). Protective immunity to Pasteurella haemolytica antileukotoxin, Haemophilus somnus, bovine herpesvirus-1 G-IV glycoprotein, bovine viral diarrhea virus, and Mycoplasma spp. may be necessary to reduce the occurrence of UF. Animals with UF are at an increased risk of overall and hemophilosis mortality.     

Pulsed Doppler intraoperative flow assessment and midterm coronary graft patency

BACKGROUND: This study was designed to assess the value of hemodynamic measurements taken intraoperatively in predicting midterm patency of coronary bypass grafts. METHODS: A pulsed Doppler flowmeter was routinely used during operation to determine the hemodynamic parameters of coronary bypass grafts. During a 7-year period, 85 patients underwent angiographic evaluation. As a result, a thorough hemodynamic assessment of 214 grafts (89 arterial and 125 venous) at initial operation was available for analysis. RESULTS: The overall patency rate was 88.3%. The mean flow measured intraoperatively in 168 intact grafts was 60+/-3 mL/min (range, 9 to 230 mL/min), and the resistance was 1.8+/-0.1 peripheral resistance units (range, 0.3 to 9.0 peripheral resistance units). The mean flow was 36+/-5 mL/min (range, 2 to 107 mL/min), and the resistance was 5.9+/-2.0 peripheral resistance units (range, 0.6 to 46.0 peripheral resistance units) in 25 grafts found occluded at angiographic evaluation. Multivariate analysis identified three independent variables associated with a reduced patency rate: increased resistance as measured in the graft (p = 0.012), increasing interval of control angiography (p = 0.006), and preoperative cardiogenic shock (p = 0.040). CONCLUSIONS: The prognosis for midterm patency of aortocoronary bypass grafts depends on the intraoperative hemodynamic status.     

Evaluation of the cochlear aqueduct patency: comparison of 2 noninvasive techniques

Variations in cephalo-rachidian fluid pressure can be transmitted to the middle ear through the cochlear aqueduct (CA). This gives us a non-invasive manner to evaluate any changes in fluid pressure by measuring middle ear impedance (impedancemetry). The present study compared two indirect methods for measuring intracranial pressure: a) impedancemetry during evoked jugulo-tympanic reflex (JTR) and b) study of the tympanic membrane (TM) fine motility using a MMS-10 analyzer. The latter is a new procedure involving the indirect evaluation of the fluid pressure. In fact, when the CA is open the labyrinthine fluid pressure is transmitted to the oval window, the stapes platina and, finally, to the tympanic membrane where it can be measured with an MMS-10 unit. This equipment can measure nanoliter shifts in the TM. In particular, comparison between the clinostatic and orthostatic tympanic motility measurements enable one to establish whether the CA is patent or not. In the present study 15 subjects were examined using both a) impedancemetry during jugular compression and b) analysis of the TM shift using an MMS-10 unit. In 14 of the 15 cases there was good correlation between the data obtained using both methods: in all but one case it proved possible to record a JTR-induced variation in impedance whenever the MMS-10 indicated that the CA was open. The results suggest that, in clinical practice, the two methods can be used in parallel for non-invasive monitoring of variations in intracranial pressure in patients with neurological involvement. On the other hand, in the E.N.T. field these techniques could be used to study inner ear pathologies causing dynamic alterations of the endolabyrinth fluids (endolymphatic hydrops, labyrinthine fistula).     

New noninvasive method for coronary flow reserve assessment: contrast-enhanced transthoracic second harmonic echo Doppler

BACKGROUND: We tested the hypothesis that blood flow velocity could be recorded in the left anterior descending coronary artery (LAD) during transthoracic echocardiography by use of second harmonic echo Doppler modality along with contrast enhancement (intravenous Levovist) at rest and after pharmacologically induced maximal vasodilation to assess coronary flow reserve (CFR) with a totally noninvasive approach. METHODS AND RESULTS: Fifty-six consecutive patients undergoing coronary angiography underwent transthoracic contrast-enhanced pulsed-wave Doppler recording of blood flow velocity in the LAD by use of harmonic color Doppler as a guide at rest and after maximal vasodilation by dipyridamole infusion. Contrast enhancement with the harmonic mode greatly improved the success rate of recording adequate pulsed-wave Doppler signal in the LAD. CFR was (mean+/-SD) 1.54+/-0.7 in patients with (group 1) and 2. 79+/-0.9 in patients without (group 2) significant LAD stenosis (lumen narrowing >70%) (P<0.001); sensitivity and specificity in detecting significant LAD stenosis were 86% and 90%, respectively. There was close agreement between CFRs determined by this new method and intracoronary Doppler flow wire. CONCLUSIONS: Contrast-enhanced transthoracic echo Doppler with the harmonic mode is a feasible and promising technique for assessing CFR in a totally noninvasive way.     

Early and late assessment of the Micro Stent PL coronary stent for restenosis and suboptimal balloon angioplasty

Dematiaceous fungi are being increasingly recognized as pathogens in organ transplant recipients. We describe a case of invasive esophagitis due to Cladophialophora bantiana in a small bowel transplant recipient and review a total of 34 cases of infections due to dematiaceous fungi in organ transplant recipients. The median time to the onset of fungal infection after transplantation was 22 months. Clinically, two distinct patterns of infections were observed: 79% of the patients had skin and/or soft-tissue infections or joint infections (predominantly due to Exophiala species), and 21% had systemic invasive infections (predominantly brain abscesses due to Ochroconis gallopavum [Dactylaria gallopava, Dactylaria constricta var. gallopava]). The overall mortality rate among the patients with skin and/or soft-tissue infections or joint infections and the patients with systemic invasive disease was 7% and 57%, respectively; two of five patients with brain abscesses were cured with antifungal therapy. Recognition of infections due to dematiaceous fungi is important since these infections, unlike invasive aspergillosis, may be more amenable to therapy.     

Experience with the AVE Micro stent in native coronary arteries

Experience with implantation of 62 AVE Micro stents is described. Stents were quickly and successfully deployed in 62 of 63 attempts (98.4%), in tortuous coronary vessels, through proximally deployed stents, and under conditions of hemodynamic instability. It is therefore a very attractive choice to treat difficult anatomy during urgent situations.     

Preliminary clinical experience with the Bard XT coronary stent

PURPOSE: The purpose of this work is to show how variations in inhalation speed of xenon gas affect cerebral blood flow (CBF) values obtained using the end-tidal method on xenon-enhanced CT (Xe-CT). We tried to clarify whether arterial xenon concentration could keep up with end-tidal xenon concentration by evaluating the effect of xenon inhalation speed on calculated CBF values. METHOD: The same subject underwent two or three consecutive Xe-CT examinations, varying xenon inhalation speed. The rate constants of applied inhalation speeds were 0.1-0.15 min-1 (low speed), 0.25-0.3 min-1 (middle speed), and 1-2 min-1 (high speed), respectively. RESULTS: No significant difference was observed among the CBF values of the same subject obtained under different inhalation speeds. CONCLUSION: End-tidal xenon can closely reflect arterial xenon under the customary method of xenon supply. The end-tidal method can provide reliable absolute CBF values, assuming actual CBF values are substantially unchanged regardless of the inhalation speed variation applied in this work.     

Treatment of ostial lesions of the left anterior descending coronary artery with Palmaz-Schatz coronary stent

We evaluated acute and long-term clinical and angiographic results of elective Palmaz-Schatz coronary stent implantation for left anterior descending coronary artery (LAD) ostial stenosis in 23 consecutive patients. Eight patients had stable angina, 14 had unstable angina, and 1 had recent myocardial infarction. Sixteen patients had single-vessel, 5 had double-vessel, and 2 had triple-vessel disease. Clinical success without major complications (death, acute myocardial infarction, emergency coronary artery bypass grafting) was obtained in all cases and technical success in 20 cases (86.9%). After stenting, minimal lumen diameter increased from 1.05 +/- 0.45 mm to 2.89 +/- 0.52 mm (p < 0.001), and percent diameter stenosis decreased from 65.49% +/- 13.36% to 2.94% +/- 19.93% (p < 0.001). One case of subacute thrombosis and no major bleeding occurred. Twenty patients were followed-up for 6 months, during which no acute cardiac event (death, acute myocardial infarction) was observed. Eighteen patients were eligible for follow-up coronary angiography; restenosis (> or = 50% diameter stenosis) was observed in 4 (22.2%). Minimal lumen diameter was 1.77 +/- 0.55 mm, percent diameter stenosis was 39.66% +/- 17.62%, late loss was 1.01 +/- 0.69 mm, net gain was 0.79 +/- 0.55 mm, and loss index (late loss/acute gain) was 0.53 +/- 0.37. This study suggests that elective Palmaz-Schatz stent implantation may be a safe and successful treatment of LAD ostial lesions and provides a large increase in lumen diameter.     

Combining B-mode ultrasound with pulsed wave Doppler for the assessment of tubal patency

This study was conducted to determine whether the additional use of pulsed wave Doppler improves the diagnostic capacity in assessing tubal patency by hysterosalpingo contrast sonography (HyCoSy). A total of 210 women with a history of infertility were included in this study. HyCoSy was performed after intrauterine injection of Echovist 200. For the assessment of tubal patency B-mode scanning and pulsed wave Doppler ultrasound were performed in the proximal and distal tubal segments. With the combined sonographic procedure 297 tubes (74%) were rated patent, 35 (8%) incompletely obstructed and 70 (18%) completely obstructed. A total of 252 tubes were additionally examined by laparoscopy for reference purposes. Concordant results for both methods were found in 92% of tubes, nine had been rated false negative and 10 tubes appeared to have been rated false positive. The combined sonographic specificity was found to be 85% with a sensitivity of 95%. Peritubal adhesions detected by laparoscopy were found to be the reason for false positive sonographic results in 60% of cases. In conclusion, the combined B-mode and pulsed wave Doppler examination appears to be a non-invasive and low-cost test for the assessment of tubal patency, which should be performed during diagnostic work-up for infertility.     

Subintimal stent implantation for the treatment of a chronic coronary occlusion

Subintimal passages of the guide wire during mechanical recanalization of chronic coronary occlusions are frequent and may result in the inability to reestablish anterograde flow in the distal coronary lumen. By using coronary stents, a conduct through the subintimal pathway can be obtained, allowing long-term restoration of the anterograde blood flow. We report on a case of a long, subintimal vessel reconstruction of a five-year-old coronary occlusion. Under intravascular ultrasound guidance, multiple coronary stents were implanted and good procedural and long-term clinical and angiographic results were achieved.     

Ultrafast computed tomographic scanning to assess patency of coronary artery stents in bypass grafts

Anginal chest pain after implantation of coronary stents in bypass grafts is a concern because it suggests the possibility of occlusion. Coronary angiography is the definitive method for determining patency of a stent; however, this procedure is relatively contraindicated in a patient receiving warfarin sodium, who has a therapeutic international normalized ratio. An alternative method for determining patency of a stent is by ultrafast computed tomography. This new, minimally invasive technique shows promise for determining blood flow within the large vessels of the thorax. Herein we describe a case in which a metallic stent placed in a vein graft was noninvasively established to be patent, despite chest pain in the patient. This method may be clinically applicable for determining patency of stents in vein grafts in the setting of patients with chest pain who have undergone complete anticoagulation.     

Reproducibility of the intravascular ultrasound assessment of stent implantation in saphenous vein grafts

IVUS measurements of stent and reference lumen dimensions and cross-sectional areas are highly reproducible. Furthermore, paramedical personnel can be trained to perform these measurements accurately. Thus, IVUS measurements may become the gold standard for the acute, chronic, and serial assessment of stent implantation procedures.     

Efficacy of Doppler ultrasonography for assessment of transjugular intrahepatic portosystemic shunt patency

PURPOSE: To assess the efficacy of Doppler ultrasonography (US) as a noninvasive method for monitoring patency of the transjugular intrahepatic portosystemic shunt (TIPS). METHODS: Twenty-nine patients who had received TIPS for bleeding esophagogastric varices and/or refractory ascites with portal hypertension underwent Doppler US studies within 2 weeks after TIPS. Further studies were performed in 15 of them at 6 months, in 9 at 1 year, and in 4 at 2 years for a total of 57 US studies. The US findings were compared with the angiographic findings obtained at the same time. RESULTS: In 45 of the 57 studies, shunt patency was found by Doppler US, correlating to 44 patencies and one occlusion on angiography. Doppler signal in the shunt could not be detected in 12 studies resulting in the diagnosis of shunt occlusion. This correlated with angiographic occlusion in 8 studies and patency in the remaining 4. All angiographically patent shunts that were occluded by Doppler US had various degrees of stenosis. A number of technical factors were found to be responsible for Doppler US false-positive or false-negative diagnoses, some related to the type of stent used. The Doppler US sensitivity was therefore 92%, the specificity 89%. CONCLUSION: Doppler US is a reliable noninvasive method to evaluate patency of TIPS.     

Protection of side-branches in coronary lesions with a new stent design

Although the association between transverse myelitis (TM) and systemic lupus erythematosus (SLE) has been reported previously, it remains a rare clinical condition. Our experience treating three women with lupus TM within a few months is presented. In each patient, spinal cord dysfunction was accompanied by laboratory or clinical evidence of SLE. Further neurologic manifestations, such as optic neuritis, developed in all patients, suggesting other diagnoses, including multiple sclerosis (MS), Devic's syndrome, and lupoid sclerosis. The outcomes for these three women were severe disability, death, and moderate disability, respectively. The severity of outcome did not seem to correlate with the timing or intensity of treatment. Physiatrists should be aware of the potential for neurologic progression in lupus TM, because patients with this condition invariably require rehabilitation.     

Device induced thromboembolism in a bovine in vitro coronary stent model

The potential of a new bovine in vitro model to evaluate various aspects of device induced thromboembolism was studied using two test modes. First, the effect of an antithrombotic drug on stent induced thromboembolism was assessed. The antithrombotic potential of an antiplatelet agent was compared with that of the other conventional antithrombotic agents (aspirin, dipyridamole) used in the past with this in vitro model. Stent associated thrombus was assessed gravimetrically at the end of the experiment. Emboli were assessed continuously using a light scattering microemboli detection system. Second, the sensitivity of the model to flow induced thromboembolism was studied using a combination of surface roughness and stenosis. Thrombus was assessed visually, and emboli were assessed as described earlier. The results show that 1) this in vitro model is sensitive to the action of antithrombotic drugs, and to the effect of hemodynamics on thromboembolism; 2) the antiplatelet drug used in this study was effective in attenuating thromboembolism; 3) a stenosis in combination with roughness produced more emboli than roughness alone; and 4) the model was useful for the study of physical and biochemical aspects of thromboembolism.     

Electron-beam computed tomography: preliminary experiences in the Netherlands]

The difference between computer tomography (CT) and electron beam tomography (EBT) is that for CT the x-ray tube rotates in a ring round the patient, and for EBT the x-ray beam rotates itself. As a result, with EBT the speed of making images is not limited by the mechanical rotation of the tube, and 16 images can be made per second. An EBT scan of a whole thorax takes 9 seconds. Specific application areas are fast moving organs and patients who cannot remain in one position for long, e.g. children and intensive care patients. Research is being conducted into the possibilities of this non-invasive technique for the demonstration of coronary artery lesions, pulmonary embolism, pulmonary metastases and dynamic examination of the major respiratory tract. Costs of an EBT scan currently amount to Dfl. 450.--but they will probably decrease as this imaging system is developed further. The exposure to radiation is about the same as that caused by a (spiral) CT.