Contrast agent increases Doppler velocities and improves reproducibility of aortic valve area measurements in patients with aortic stenosis.

Observer variability may limit assessment of aortic stenosis by Doppler echocardiography. This study aimed to assess whether echocardiographic contrast agent improves reproducibility of aortic valve area (AVA) measurements for patients with aortic stenosis. In all, 20 patients with aortic stenosis (67 +/- 10 years old) underwent noncontrast and contrast Doppler echocardiography on 2 occasions, 3 weeks apart. Intraobserver and interobserver coefficients of reproducibility were 0.36 and 0.20 cm for left ventricular outflow tract (LVOT) diameter, and 0.38 and 0.24 cm(2) for AVA, respectively. Although intraobserver reproducibility was unaffected, contrast improved interobserver reproducibility for LVOT diameter (mean of differences -0.02 +/- 0.07 cm vs 0.01 +/- 0.10 cm, P <.05) and AVA (mean of differences 0.02 +/- 0.10 cm(2) vs 0.07 +/- 0.12 cm(2), P <.05). Prevalve and postvalve velocities were increased with contrast compared with noncontrast imaging (prevalve, 1.07 +/- 0.20 vs 0.94 +/- 0.19 m/s, P <.01; postvalve, 3.76 +/- 0.87 vs 3.47 +/- 0.78 m/s, P <.01). We conclude that contrast significantly increases Doppler velocities and produces modest improvements in reproducibility of LVOT diameter and AVA. We suggest that, when assessing patients with aortic stenosis, contrast agents should be considered in patients who are difficult to image with poor baseline LVOT images or Doppler studies, or where there is poor interobserver reproducibility.     

Microleakage and nanoleakage: influence of laser in cavity preparation and dentin pretreatment.

OBJECTIVE: The purpose of this study was to verify if the application of the Nd:YAG laser following pretreatment of dentin with adhesive systems that were not light cured in class V cavities and were prepared with Er:YAG laser would promote better sealing of the gingival margins when compared to cavities prepared the conventional way. BACKGROUND DATA: Previous studies had shown that the pretreatment of dentin with laser irradiation after the application of an adhesive system is efficient in achieving higher shear bond and tensile bond strength. MATERIALS AND METHODS: Er:YAG laser (Kavo-Key, Germany) with 350 mJ, 4 Hz, and 116.7 J/cm2 was used for cavity preparation. The conventional preparation was made with diamond bur mounted in high-speed turbine. Dentin treatment was accomplished using an Nd:YAG laser (Pulse Master 1000, ADT. USA) at 60 mJ, 10 Hz, and 74.65/cm2 following application of the adhesive system. The cavities were stored with Single Bond/Z100 and Prime & Bond NT/TPH. Eighty bovine incisors were used, and class V preparations were done at buccal and lingual surfaces divided into eight groups: (1) Er:YAG preparation + Prime & Bond NT + TPH; (2) Er:YAG preparation + Single Bond + Z100; (3) Er:YAG preparation + Single Bond + Nd:YAG + Z100; (4) Er:YAG preparation + Prime & Bond NT + Nd:YAG + TPH; (5) conventional preparation + Prime & Bond NT + TPH; (6) conventional preparation + Single Bond + Z100; (7) conventional preparation + Single Bond + Nd:YAG + Z100; (8) conventional preparation + Prime & Bond NT + Nd:YAG + TPH. All specimens were thermocycled for 300 full cycles between 5 degrees C+/-2 degrees C and 55 degrees C+/-2 degrees C (dwell time of 30 sec), and stored in 50% silver nitrate solution for 24 h soaked in photodeveloping solution and exposed to fluorescent light for 6 h. After this procedure, the specimens were sectioned longitudinally in 3 portions and the extension of microleakage at the gingival wall was determined following a criteria ranging from 0 to 4 using scanning electron microscopy (SEM). The medium portion sectioned of each specimen was polished and prepared for nanoleakage avaliation by SEM. RESULTS: Kruskall-Wallis and Miller statistical tests determined that group 3 presented less microleakage and nanoleakage. CONCLUSION: Application of the Nd:YAG laser following pretreatment of dentin with adhesive Single Bond non-photocured Single Bond adhesive in cavities prepared with Er:YAG promote better sealing of the gingival margins.     

Studies of Blood Flow in Aorta-to-Coronary Venous Bypass Grafts in Man

Pressure-flow measurements were obtained from the vein graft of 57 patients undergoing a single aorta-to-coronary bypass procedure.The flow contour was similar to phasic left coronary artery flow in dogs except for a transient increase during systole possibly related to elongation of the graft. Flow was highest during bypass and decreased to a stable value 30 min after bypass. In 42 patients, flow at this time was 35+/-2 cm(3)/min (mean+/-sem).NO CORRELATIONS WERE DEMONSTRATED BETWEEN FLOW AND THE FOLLOWING: left vs. right grafts, presence or absence of collaterals, total vs. partial block, or the presence or absence of ventricular dyskinesis. In 32 patients, no correlation between these anatomic findings and the presence of reactive hyperemia was demonstrated. In 17 patients, occlusion of the graft for 10 sec resulted in a mean 51.5% flow debt repayment.In nine patients, injection of 0.3 mug of isoproterenol into the graft increased flow from 45+/-6 to 69+/-9 cm(3)/min within 4-7 sec without changes in rate, pressure, time derivative of left ventricular pressure (LV dp/dt), or left ventricular end diastolic pressure (LVEDP). Maximum increases to 87+/-10 cm(3)/min occurred 12-20 sec after injection with concomitant changes in these parameters.Intravenous infusion of norepinephrine did not change vascular resistance, whereas phenylephrine did. In six patients, injection of 0.2 mug of norepinephrine into the graft decreased flow from 49+/-6 to 25+/-5 cm(3)/min within 5-8 sec.Intravenous infusion of 0.15 mg of nitroglycerin decreased coronary vascular resistance from 2.7+/-0.4 to 2.3+/-0.3 mm Hg/cm(3) per min. In five patients, 0.12 mg of nitroglycerin injected into the graft increased flow from 46+/-7 to 71+/-13 cm(3)/min and lasted 20-40 sec.     

Correlation between prostate cancer grade and vascularity on color doppler imaging: preliminary findings

PURPOSE: We examined the relationship between the amount of prostate cancer-associated vascularity as seen on color Doppler imaging and the tumor grade. METHODS: Transrectal color Doppler imaging of the prostate was performed in 54 patients with prostate cancer. Color flow signal/total pixel ratios (SPRs) of selected images were calculated using the ratio of the number of pixels showing color Doppler signals to the total number of pixels within the lesion. All the patients underwent prostate biopsy guided by transrectal sonography. Gleason scores were determined from the biopsy specimens. RESULTS: Color Doppler signals were demonstrated in the lesions of 91% (49/54) of the patients. The mean SPRs of prostate cancers 3 cm or smaller and larger than 3 cm were 0.15 +/- 0.07 and 0.11 +/- 0.04 (+/- standard deviation), respectively (p < 0.05). The mean SPRs of well- (Gleason score of 2-4), moderately (Gleason 5-7), and poorly (Gleason 8-10) differentiated prostate cancers were 0.08 +/- 0.03, 0.12 +/- 0.06, and 0.17 +/- 0.11, respectively (r = 0.45; p < 0.01). CONCLUSIONS: The refinement of color Doppler equipment has improved the detection of color Doppler signals associated with prostate cancer. Our study shows a correlation between prostate cancer-associated vascularity as shown on color Doppler imaging and the tumor grade.     

In vitro study of the Nd:YAG laser effect on human dental enamel: optical and scanning electron microscope analysis

OBJECTIVE: The Nd:YAG laser irradiation of dental enamel was evaluated in enamel demineralization experiments in a Streptococcus mutans culture media. SUMMARY BACKGROUND DATA: Previous studies had shown that a continuous wave Nd:YAG laser at an energy of approximately 67 mJ may induce an increased acid resistance in human dental enamel when exposed to severe demineralization conditions. METHODS: Enamel windows of 3 x 4 cm in the buccal surface were irradiated with a continuous wave Nd:YAG laser at a wavelength of 1,064 microns using energy densities of from 83.75 to 187.50 J/cm2. Enamel windows of 3 x 4 cm on the lingual surface served as control (without the laser irradiation). The enamel windows were then exposed to a Streptococcus mutans culture media at a temperature of 37 degrees C for 15 and 21 days. The laser effects and demineralization were examined both by optical microscopy and scanning electron microscopy (SEM). RESULTS: A comparison between the lased and the unlased windows of enamel showed fusion and recrystalization of the enamel and increased acid-resistance in all groups irradiated with the Nd:YAG laser. On the other hand, the 3 x 4 delimited enamel surfaces from the control group (not irradiated with the Nd:YAG laser) showed 100% demineralization. CONCLUSIONS: These findings are consistent with the finding that laser irradiation of dental results in significant reduction of the effective solubility of enamel mineral.     

Use of intravascular Doppler velocimetry during angioplasty of failing hemodialysis shunts.

To correlate angiographic stenoses, pressure gradients, and intravascular Doppler velocity measurements, we studied 12 patients with failing hemodialysis shunts who were undergoing percutaneous transluminal angioplasty. Seven patients had a stenosis at the site of venous anastomosis, two had a stenosis of the central vein, and three had stenoses at both sites. The mean degree of angiographic stenosis was reduced by percutaneous transluminal angioplasty from 74 +/- 8% to 23 +/- 7% diameter, and the mean pressure gradient was reduced from 48 +/- 13 to 7 +/- 3 mm Hg. The proximal to distal peak systolic velocity ratio was significantly different before and after the angioplasty (3.3 +/- 1.4 and 1.6 +/- 0.6, respectively, P < 0.001). The lesion to proximal peak systolic velocity ratio was 2.5 +/- 0.8 before and 1.2 +/- 0.2 after percutaneous transluminal angioplasty (P < 0.001). Cutoff values of 1.9 for the proximal to distal velocity ratio and 1.5 for lesion to proximal velocity ratio were used to assess hemodynamic significance of lesions in our series. Velocity gradients derived from intravascular Doppler measurements correlate with angiographic and pressure measurements in failing hemodialysis shunts treated with percutaneous transluminal angioplasty. Further studies are needed to assess the exact role of these measurements in percutaneous revascularization procedures.     

Assessment of coronary flow reserve by adenosine transthoracic echocardiography: validation with intracoronary Doppler.

OBJECTIVE: Data on the accuracy of transthoracic echocardiographic (TTE) analysis of coronary flow reserve are scarce. We compared coronary flow reserve measurements assessed using TTE with those achieved using the gold standard of intracoronary Doppler. METHODS: Twenty-one patients admitted for elective coronary angioplasty to the circumflex or left anterior descending (LAD) coronary artery underwent TTE immediately before angioplasty, both at rest and during intravenous administration of adenosine 140 microg/kg/min. Transthoracic images of distal LAD coronary diameter and coronary flow were obtained in 14 patients (66%). These patients then underwent intracoronary Doppler analysis of coronary flow reserve in the distal LAD coronary artery. In 1 patient with a proximal LAD artery lesion, the narrowing could not be crossed with the Doppler guidewire. Paired data on coronary flow reserve were therefore available in 13 patients. RESULTS: Patients were aged 61.7 +/- 8.3 years. Ten were men. Body mass index was 26.3 +/- 4.6 kg/m(2). Resting distal LAD artery blood flow was 18.4 +/- 9.0 mL/min assessed by TTE versus 17.6 +/- 8.1 mL/min by intracoronary Doppler. Hyperemic flow was 36.3 +/- 23.4 versus 33.1 +/- 19.2 mL/min, respectively. Coronary flow reserve was therefore 1.89 +/- 0.66 by TTE compared with 1.83 +/- 0.62 by intracoronary Doppler. Limits of agreement for coronary flow reserve were -0.28 to +0.44, well within boundaries of clinical acceptability. CONCLUSION: Transthoracic echocardiography is capable of providing accurate data on coronary flow reserve in the distal LAD coronary artery. As a truly noninvasive modality, this technique offers advantages over traditional invasive procedures.     

Nd: YAG Laser-Photocoagulation: Acute Electrophysiological, Hemodynamic, and Morphological Effects in Large Irradiated Areas

Laser-photocoagulation (LPC) of arrhythmogenic myocardium has been reported to successfully ablate ventricular tachycardia. The purpose of this study was to investigate the acute hemodynamic and electrophysiological effect of continuous laser energy (Nd:YAG, 1060 nm) applied via a 0.4-mm quartz fiberoptic on the epicardial surface of the heart in nine dogs. A total of 51 +/- 2.3 pulses was delivered in each animal to induce homogeneous tissue necrosis. Applied energy was 12.3 +/- 2.7 J/mm2, irradiated surface measured 12.6 +/- 3.0 cm2, lesion depth was 6.3 +/- 1.2 mm (range: 5.0-8.1 mm), lesion volume was 8.1 +/- 2.8 cm3 (6.8% of left ventricular [LV] mass). After LPC, epicardial stimulation threshold significantly rose from 1.0 +/- 0.3 to 10.2 +/- 4.9 mA in the border zone to nontreated tissue and from 0.9 +/- 0.4 to 32 +/- 15.7 mA in the center of the lesions. Loss of epicardial activation in the irradiated areas could be demonstrated by epicardial mapping. Ventricular extrasystoles during LPC were seen in all dogs, ventricular tachycardia in seven, and ventricular fibrillation in two dogs. After LPC, cardiac output and LV dP/dtmax significantly decreased by 14.2% and 11.2%. LPC induced predictable homogeneous tissue edema, eosinophilic staining, contraction band necrosis, and sharp demarcated hemorrhagic border zones with a sharp electrical border zone to nontreated tissue and loss of epicardial activation. During LPC, various arrhythmogenic effects could be observed. However, no persistent arrhythmic activity developed after LPC. The results confirm the feasibility of epicardial LPC of the myocardium. Although not rested in this study, LPC of arrhythmogenic tissue may also be feasible as a treatment modality of ventricular tachycardia.     

Doppler estimation of changes in pulmonary artery pressure during hypoxic breathing

To assess the use of Doppler echocardiographic screening for abnormal pulmonary vasoreactivity, we measured pulmonary artery pressure in 10 adult patients and 11 normal subjects while recording Doppler right ventricular outflow acceleration time, pre-ejection period, and ejection time. In the normal subjects we also measured the changes in each parameter after 10 minutes of hypoxic breathing (FIO2 = 0.12). Mean pulmonary artery pressure increased by 39% during hypoxia (13 +/- 4.3 to 18 +/- 5.4 mm Hg). In the patients and normal subjects at rest, mean pulmonary artery-pressure correlated well with acceleration time (r = -0.84; standard error of the estimate, 6.6 mm Hg; p = 0.0001). Over the narrow range of mean pulmonary artery pressure in normal subjects at rest, mean pulmonary artery pressure did not correlate well with acceleration time, acceleration time/pre-ejection period, or acceleration time/right ventricular ejection time. However, changes in mean pulmonary artery pressure induced by hypoxic breathing did correlate with changes in acceleration time/right ventricular ejection time (r = 0.73; standard error of the estimate, 2.3 mm Hg; p = 0.01). Doppler ultrasound may offer a noninvasive means for detecting abnormal pulmonary vasoreactivity in asymptomatic individuals at risk for developing pulmonary hypertension.     

The effects of low-level energy density Nd:YAG irradiation on calculus removal

This study assessed the effects of using an Nd:YAG laser to remove dental calculus from root surfaces. Human extracted molar teeth, with extensive calculus attachment to root surfaces, were irradiated with an Nd:YAG beam [power densities (PD) = 1.09 W/cm 2 and 2.19 W/cm 2; energy densities (ED) = 49.2 J/cm 2 and 98.4 J/cm 2]. An additional group of teeth was instrumented with a Gracey 11/12 curette. A separate group of untreated specimens served as controls. Specimens were examined under scanning electron microscopy and rated as to the degree of calculus detachment from root surfaces. Nd:YAG irradiation at low ED did not appreciably affect the integrity of the calculus root surface attachment. The higher-ED Nd:YAG irradiation appeared to mimic the type of calculus removal depicted with conventional hand instrumentation. Root surface damage from both laser ablations was negligible.     

Doppler-ophthalmomanometry in patients with obstruction of the carotid arteries

A novel noninvasive method to determine simultaneously ophthalmic artery pressure (OAP) and flow direction based on Doppler ultrasound principles is presented: ophthalmomanometry-Doppler (OMD). Studies performed on 25 angiographically proven normal subjects with direct recording of the internal carotid artery pressure (ICP) and indirect determination of the brachial artery pressure (BAP) demonstrated that OAP values assessed by the OMD device are highly correlated with simultaneous ipsilateral intraarterial systolic ICP measurements (r = 0.95, n = 10) and with simultaneous recordings of the BAP (r = 0.88, n = 15). In 50 patients presenting angiographically occlusions and 52 patients presenting angiographically stenoses (greater than 60%) of the carotid artery the measured Doppler ophthalmic pressure index (OPI = ratio of the ophthalmic to systemic blood pressure) was lower ipsilateral to an occlusion (0.46 +/- 0.08) than ipsilateral to a stenosis (0.54 +/- 0.08; p less than 0.001) of the carotid artery. In both it was clearly diminished compared to normal values (0.68 +/- 0.04; p less than 0.001). In carotid artery occlusions, the ipsilateral OPI was 0.46 +/- 0.06 for antegrade (n = 17) and 0.46 +/- 0.09 for retrograde (n = 28) ophthalmic artery flow. In carotid artery stenoses, the ipsilateral OPI was 0.55 +/- 0.07 for antegrade (n = 41) and 0.48 +/- 0.06 for retrograde (n = 9) ophthalmic artery flow (p less than 0.01). It is concluded that in carotid occlusions presenting a longer disease history extra-intracranial collateralisation via the ophthalmic artery are as efficient as a functional circle of Willis.     

Doppler sonography of deep cavernosal artery of the penis: variation of peak systolic velocity according to sampling location.

To determine if there are significant variations in the peak systolic velocity of cavernosal arteries according to the Doppler sampling location, Doppler sonography was performed in 32 patients with erectile dysfunction and 15 control patients. Doppler spectral waveforms were obtained at proximal and distal locations in cavernosal artery. The peak systolic velocity of the cavernosal artery was 39.0 +/- 11.2 cm/sec in proximal portion and 20.0 +/- 5.6 cm/sec in distal portion in patients with erectile dysfunction. In control patients, the peak systolic velocity was 39.8 +/- 8.0 cm/sec in proximal portion and 21.3 +/- 5.5 cm/sec in distal portion. The peak systolic velocity of the cavernosal artery varies significantly according to the sampling location in patients with erectile dysfunction as well as in control patients. Our study demonstrated that the sampling location needs to be standardized in performing Doppler sonography of the cavernosal arteries, and we propose the proximal cavernosal artery where it angles posteriorly as the standardized sampling location.     

Potential use of transthoracic echocardiography in the assessment of coronary flow reserve.

Coronary flow reserve provides a gold standard assessment of the epicardial and microvascular coronary circulation. However, measurement of coronary flow reserve is limited by the invasiveness or complexity of the methods hitherto available. We investigated whether transthoracic echocardiography could be used to assess coronary flow reserve. We imaged distal left anterior descending coronary artery diameter and flow in 14 healthy volunteers, both at rest and during intravenous infusion of adenosine (140 microg/kg per minute). Volunteers were men, with an average (+/-SD) age of 28.4 +/- 6.3 years. Complete data were acquired in 11 cases. Average distal left anterior descending coronary artery diameter was 0.213 +/- 0.03 cm. Velocity time integral rose from 8.6 +/- 2.1 cm to 27.7 +/- 5.6 cm with adenosine infusion. Heart rate rose from 64.7 +/- 9. 8 to 75.3 +/- 11.7 bpm. The Doppler angle of incidence to flow was 42.4 +/- 8.7 degrees. Resting distal left anterior descending coronary artery flow was therefore calculated as 13.4 +/- 3.2 mL/min and hyperemic flow as 51.2 +/- 16.2 mL/min, yielding a coronary flow reserve of 3.81 +/- 0.6. We conclude that coronary flow reserve can be assessed in a selected population with the use of transthoracic echocardiography and an intravenous infusion of adenosine. The simplicity of this noninvasive technique suggests that it could become a useful tool for measurement of coronary flow reserve if imaging success rates can be optimized.     

Doppler evaluation of the uterine and spiral arteries from different sampling sites and phases of the menstrual cycle during controlled ovarian hyperstimulation.

OBJECTIVE: To compare the pulsatility index (PI) and resistance index (RI) at different sampling sites of the uterine and spiral arteries in the early and mid-menstrual phases. MATERIALS AND METHODS: The uterine and spiral arteries of 110 women undergoing similar ovarian hyperstimulation and intra-uterine insemination regimes were examined using transvaginal color Doppler ultrasound. The uterine artery was sampled at five sites: (1) ascending branch; (2) descending branch; (3) proximal, near branch division; (4) mid, 0.5 cm distal to the division; (5) lateral location, 1 cm distal to the division. The spiral artery was sampled at three sites: (a) anterior; (b) fundal; (c) posterior. The uterine and spiral arteries were examined twice, on days 2-3 and 14-16, respectively, of the menstrual cycle. The women were also grouped according to age at examination, < or = 30 years and > 30 years. The PI and RI values for different sites, menstrual phase, and age were compared. RESULTS: The mean PI and RI values of the uterine artery were: (1) 2.86 +/- 1.20 and 0.92 +/- 0.13; (2) 2.66 +/- 1.15 and 0.89 +/- 0.12; (3) 2.88 +/- 1.26 and 0.90 +/- 0.15; (4) 3.03 +/- 1.02 and 0.91 +/- 0.07; (5) 3.23 +/- 1.38 and 0.89 +/- 0.12; and of the spiral artery were (a) 1.61 +/- 1.01 and 0.69 +/- 0.17; (b) 1.69 +/- 0.74 and 0.74 +/- 0.17; (c) 1.73 +/- 0.86 and 0.68 +/- 0.17. The PI values for uterine and spiral arteries at two phases of the menstrual cycle were 2.92 +/- 1.18 and 1.55 +/- 0.72 (days 2-3); 3.11 +/- 1.15 and 1.80 +/- 1.02 (days 14-16), respectively; for younger women (age < or = 30 years) these values were 2.83 +/- 1.22 and 1.6 +/- 0.85 and for older women (age > 30 years) 3.0 +/- 1.34 and 1.72 +/- 0.96, respectively. CONCLUSIONS: There were no significant differences in PI and RI values of the uterine and spiral arteries at different sampling sites, phase of the menstrual cycle or age. The higher PI values tended to occur in the lateral uterine artery and posterior spiral artery, during the mid-menstrual phase and in the older age group. The PI and RI values of the mid-uterine and fundal spiral artery sampling sites are representative of the whole uterine artery and spiral artery, respectively.     

Laser ablation and the need for intra-arterial imaging

In 48 patients with severe claudication due to a total obstruction of the femoropopliteal artery, percutaneous recanalization was attempted with a 2.2 mm diameter rounded sapphire contact probe in conjunction with a continuous wave Nd:YAG laser. In eight patients the contact probe laser catheter took a subintimal course that could not be redressed. Laser recanalization needs high-resolution diagnostic information on the complex anatomy of the obstruction. Intra-arterial ultrasound imaging may provide the necessary information to evaluate, monitor or guide novel angioplasty techniques. The design of an ultrasound catheter which combines high-resolution diagnostic imaging with steerability, flexibility and controlled ablation is now the major engineering challenge in interventional cardiology.     

Early assessment of coronary flow reserve by transthoracic Doppler echocardiography predicts late remodeling in reperfused anterior myocardial infarction.

BACKGROUND: Microvascular integrity is an essential determinant of favorable late outcome in reperfused myocardial infarction. Coronary flow reserve (CFR) can be assessed by transthoracic Doppler echocardiography and provides a functional estimate of microvascular integrity downstream from the patent infarct-related vessel. OBJECTIVE: We sought to assess the effects of CFR in predicting late left ventricular (LV) remodeling in patients with reperfused acute anterior myocardial infarction treated with primary angioplasty. METHODS: In all, 31 patients admitted with acute anterior myocardial infarction underwent primary angioplasty of the infarct-related vessel. After angioplasty, angiographic thrombosis in myocardial infarction (TIMI) grade and myocardial blush were scored. On the first day, all underwent stress echocardiography and CFR evaluation of left anterior descending coronary artery by transthoracic Doppler. All patients had resting 2-dimensional echocardiography at 1, 3, and 6 months for assessment of LV function. RESULTS: CFR could be successfully assessed in 31 patients. After 6 months 5 patients showed LV dilatation (group I), whereas 26 patients did not show significant variation (group II). On day 1, CFR was higher (group I = 1.43 +/- 0.11 vs group II = 1.67 +/- 0.26, P =.005) and the deceleration time of diastolic left anterior descending coronary artery flow velocity was longer (group I = 212 +/- 41.4 milliseconds vs group II = 286 +/- 106.7 milliseconds, P <.02) in patients without, compared with those with LV remodeling, whereas there was no difference in angiographic parameters. CONCLUSION: Early assessment of CFR and the pattern of baseline diastolic coronary flow velocity by transthoracic Doppler echocardiography is feasible, safe, and more useful than angiographic indices in identifying patients at high risk of remodeling in spite of successful primary angioplasty.     

Nd:YAG激光和Er:YAG激光联合Gluma脱敏剂治疗非手术牙周治疗后牙本质敏感疗效观察

目的 评价Gluma脱敏剂、Nd:YAG激光和Er:YAG激光单独及联合治疗非手术牙周治疗引起的牙本质过敏症(DH)的疗效.方法 选择60例经非手术牙周治疗后发生DH的牙周炎患者,共计180颗患牙.将患牙随机分为6组,每组30颗,其中A组:空白对照组;B组:Gluma脱敏剂组;C组:Nd:YAG激光组;D组:Er:YA...     

Combined UV and IR laser ablation of dentine

OBJECTIVE: The aim of this study was to increase the rate of removal of dentine tissue by a 213-nm laser through the introduction of an Er:YAG assisting laser. BACKGROUND DATA: The rate of dentine removal is increased by using a CO2 laser to assist a XeCl excimer laser. METHODS: Extracted human teeth were sliced parallel to the crown and exposed to 213-nm laser and Er:YAG laser beams that were spatially and temporally aligned. The 213-nm laser radiation was generated using a Q-switched Nd:YAG (5 nsec, 10 Hz) and three nonlinear crystals. The Er:YAG laser was free running with a pulse duration of 100 microsec and a pulse repetition rate of 10 Hz. A fluence range of 5-18.6 J/cm2 (213 nm) and 0.6-1.3 J/cm2 (Er:YAG) was used. Axial ablation rates were measured for different pulse energies and pulse overlaps. RESULTS: The ablation rate of dentine increased in most cases by a factor of two. The highest ablation rate achieved was 18.3 microm/pulse +/- 2.51, which is more than twice the highest ablation rate previously published using a 213-nm laser. Changes in the pulse superpositions that were investigated did not present a significant change in the ablation rate. CONCLUSIONS: The Er:YAG laser can be used to increase the removal rate of dentine by a short-pulse ultraviolet (UV) laser.     

强脉冲光与Q-开关倍频Nd：YAG激光治疗脂溢性角化病的临床疗效对比

【目的】比较强脉冲光与Q-开关倍频Nd：YAG激光治疗脂溢性角化病的临床疗效及不良反应。【方法】收集双侧面部均有脂溢性角化皮损的患者共15例,左侧皮损使用强脉冲光治疗,治疗间隔为4～5周,连续3次为一个疗程。右侧皮损使用Q-开关倍频Nd：YAG激光治疗,治疗间隔为4～5周,疗程为1～12次。患者和医生根据照片对每次治疗的疗效及不良反应进行评价。【结果】强脉冲光治疗3次后的疗效与Q-开关倍频Nd：YAG激光治疗1～2次后的疗效经患者和医生评价差异均无显著性（S=-5,P〉0．05;S=-4．5,P〉0．05）。强脉冲光治疗后色素沉着的发生率显著低于Q-开关倍频Nd：YAG激光（P〈0．01）,所有患者均未出现水疱、瘢痕及色素减退。【结论】强脉冲光和Q-开关倍频Nd：YAG激光均能有效地治疗脂溢性角化病。在使用Q-开关倍频Nd：YAG激光治疗时应适当降低能量密度,以防色素沉着的发生率。     

Transcranial measurement of blood velocities in the basal cerebral arteries using pulsed Doppler ultrasound: a method of assessing the Circle of Willis

Transcranial pulsed Doppler ultrasound and spectral analysis were used for detection of blood velocities in the basal cerebral arteries. The Doppler transducer was placed superior to the zygomatic arch and during insonation of the middle cerebral artery care was taken to obtain maximum Doppler-shift frequency signals since this allowed a small angle between the ultrasound beam and this artery. Doppler signals were obtained from the middle, anterior, and posterior cerebral arteries in 20 volunteers with the average depth of the Doppler gate at 4.9 (4.6-5.2 cm), 5.2 (4.9-5.4 cm), and 6.3 cm (6.0-6.9 cm), respectively. These measurements were in agreement with those obtained for 15 cadaver studies, in whom the distance from the proposed site of the Doppler transducer to each basal cerebral artery was measured as 4.7 +/- 0.6, 5.3 +/- 0.5, and 5.9 +/- 0.9 cm, respectively. The reproducibility of middle cerebral artery blood velocity values was tested in seven subjects and showed a variation of not more than 8% in any individual. The method was used in combination with common carotid compression to assess four patients who had occlusive extracranial carotid disease; in three the disease was more severe on one side and reversal of blood flow in the proximal ipsilateral anterior cerebral artery was demonstrated, consistent with cross flow from the contralateral side via the anterior communicating artery of the Circle of Willis. In the fourth patient augmentation of posterior cerebral artery blood velocities during common carotid compression indicated the major collateral source was from the vertebrobasilar system.