Feasibility of using ultra-low pulse rate fluoroscopy during routine diagnostic coronary angiography.

INTRODUCTION: Coronary angiogram, while a powerful diagnostic tool in coronary artery disease, is not without an associated risk from ionising radiation. There are a number of factors that influence the amount of radiation the patient receives during the procedure, some of which are under the control of the operator. One of these is an adjustment of the fluoroscopic pulse rate. This study aims to assess the feasibility of using ultra-low pulse rate (3 pulses per second(pps)) fluoroscopy during routine diagnostic coronary angiogram procedures and the effect it has on fluoroscopy time, diagnostic clarity and radiation dose. METHODS: A retrospective study of three operators each undertaking 50 coronary angiogram procedures was performed. One of the operators used a pulse rate of 3 pps and 6 pps for fluoroscopic screening while the control groups used the standard 10 pps mode utilised at this centre. RESULTS: Results demonstrated no reduction of diagnostic clarity, up to a 58% reduction in Dose Area Product and no increase in fluoroscopy time with the 3 pps setting. CONCLUSIONS: Findings from this pilot study suggest that utilisation of ultra-low pulse rate fluoroscopy in routine transfemoral diagnostic coronary angiography in the catheterisation laboratory is feasible.

A fast fluorescence imaging flow cytometer for phytoplankton analysis.

We report a fast fluorescence imaging flow cytometer for phytoplankton analysis that can achieve a volume flow rate up to 1ml/min. The instrument shows a high immunity to motion blur in image captured with a lateral resolution of 0.75 ± 0.06 µm for a wide size range ~1 µm to ~200 µm. This is made possible by suppressing the out-of-focus light using thin light sheet illumination and image deconvolution, and by precluding the motion-blur with a unique flow configuration. Preliminary results from untreated coastal water samples show the technique has high potential as a practical field instrument for monitoring phytoplankton abundance and species composition.

A light sheet based high throughput 3D-imaging flow cytometer for phytoplankton analysis.

This paper reports a light sheet fluorescence imaging flow cytometer for 3D sectioning of phytoplankton. The instrument developed has the inherent advantages of high cell counting throughput and high spatial resolution information derived from flow cytometry and light sheet microscopy. The throughput of the instrument is quantified by the sample volume flow rate of 0.5 µl/min with a spatial resolution as achieved by light sheet microscopy. Preliminary results from 3D morphology of the internal chlorophyll-a structure of two dinoflagellates species show promising application potentials of the method for phytoplankton taxonomy of selected species and species groups.

Toward a UV-visible-near-infrared hyperspectral imaging platform for fast multiplex reflection spectroscopy.

A reflection hyperspectral imaging system covering a 350-1000nm spectral range is realized by a UV-visible-near-IR Fourier transform imaging spectrometer. The system has a simple design and good spectral and spatial resolving performance. Accurate and fast microspectroscopic measurement results on novel colloidal crystal beads demonstrate the system has practical potential for high-throughput molecular multiplex assays.

Tests of a practical visible-NIR imaging Fourier transform spectrometer for biological and chemical fluorescence emission measurements.

An imaging Fourier transform spectrometer (IFTS) designed for fluorescence emission measurements is reported. The spectral range extension from NIR to visible of the system is realized by using a simple and low-cost optical beam-folding position-tracking technique. Spectral resolution as high as 9.78cm(-1)(0.4nm at 632.8nm) and maximum image resolution up to 300x300 pixels are proved by the system tests on its optical performances. Imaging fluorescence spectra acquisition of quantum dot clusters and single 200nm diameter fluorescent beads have demonstrated the system's potential for high throughput imaging spectroscopic measurements of fluorescent biological and chemical samples.

Block to succeed: the Canadian orthopedic resident research experience.

BACKGROUND: We assessed the current state of Canadian orthopedic resident research and the effect of protected block research time on the numbers of grants obtained, research projects completed, submissions for publication, publications and conference presentations. METHODS: We administered a 27-item cross-sectional survey containing quantitative and qualitative questions to postgraduate year (PGY)-3 to -5 residents in all 16 Canadian orthopedic training programs in the academic year of Jul. 1, 2005, to Jun. 30, 2006. RESULTS: There was an overall response rate of 45% (85/188) from residents in 15 of 16 orthopedic programs: 56% (48/85) of respondents took block research time of at least 1 month (mean 5 mo). The number of months taken was positively correlated with the number of grants obtained (r = 0.28, p = 0.011) and publications (r = 0.23, p = 0.031). Residents who took block time obtained more grants (Fisher exact test 3.54, p = 0.048) and publications (Fisher exact test 6.09, p = 0.012) than those who did not take block time. About 41% (35/85) of respondents said time was the biggest obstacle to research. CONCLUSION: Providing protected block research time during residency allows Canadian orthopedic residents greater research success.

Near UV-near IR Fourier transform spectrometer using the beam-folding position-tracking method based on retroreflectors.

A near UV-near IR Fourier transform spectrometer based on a beam-folding position-tracking method realized by using retroreflectors is reported. The use of retroreflectors maintains all beams in the beam-fold arrangement in parallel with the incident beams. The beam-folding interferometer used for position tracking is arranged to have optical path symmetry with the measurement interferometer in the zero path difference position of the measurement interferometer, and the vertex of the movable retroreflector in the measurement interferometer is arranged very close to the midpoint of the vertices of two movable retroreflectors in the position-tracking interferometer. These measures keep the equivalent optical axis of the position-tracking interferometer well in line with that of the measurement interferometer even with translational misalignments. Therefore, the change in the optical path difference of the position-tracking interferometer is always synchronous to that of the measurement interferometer during the scanning process. That is, the position-tracking error can be suppressed to very small values during a scan. We have demonstrated a UV-near IR Fourier transform spectrometer with a standard quality ball-bearing translation stage achieving a resolution close to the theoretical resolution of approximately 0.28 cm(-1) at the He-Ne laser wavelength when the scan distance reaches the travel distance of over 2 cm. This was achieved without the need for elaborate optics, sophisticated detecting electronics, and high-precision servomotion control.

Giant cardiac myxoma.

Although cardiac myxomas remain an uncommon group of malignancies, they are the most common form of primary cardiac tumour. Clinical presentations can be varied with local cardiac haemodynamic consequences, valvular insufficiency or even embolic phenomena. We present a case of a 46-year-old man with chronic abdominal pain and discuss a number of diagnostic challenges that were confronted up until a definitive diagnosis of cardiac myxoma was made. The resultant outcome was excellent with the patient achieving complete recovery from long term disabling symptoms.

Subclavian artery occlusion causing acute myocardial infarction in a patient with a left internal mammary artery graft.

Although atherosclerotic disease of the subclavian artery has previously been reported to cause coronary-subclavian steal syndrome, acute myocardial infarction because of occlusion of the subclavian artery in a graft-dependent coronary circulation is an uncommon and previously unreported mode of clinical presentation. Increasingly, patients undergoing high-risk cardiopulmonary procedures have comorbidities with extensive atherosclerotic disease of many vascular beds including coronary, cranial, and peripheral. Our discussion reviews the clinical presentation of such a case and highlights some of the important treatment options available when confronted with such a finding. The successful outcome achieved by percutaneous stenting of the subclavian artery and salvage of the graft may indicate that this modality is the initial treatment of choice in such cases.

Fourier transform ultraviolet-visible spectrometer based on a beam-folding technique.

A beam-folding technique in optical interferometry, where the number of beam folds used can be very large, is reported. This technique can be used as a low-cost position-tracking method in a Fourier transform spectrometer (FTS) to cover the broad spectral range from UV to IR. The main advantage gained is the simple position-tracking algorithm used in sampling the interferogram. We have developed a UV-visible FTS, whose wavelength coverage is limited only by the optical elements (350 nm(-1) microm with off-the-shelf components). Preliminary results show that it can achieve a resolution of approximately 4 cm(-1) even with a ball-bearing translation stage.

What is the best contemporary treatment for in-stent restenosis?

In-stent restenosis (ISR) remains a challenging problem in percutaneous coronary intervention and the optimal treatment strategy remains unclear. The aim of this study was to compare the 18 month clinical outcomes in patients receiving sirolimus-eluting stents (SES) with vascular brachytherapy (VBT) for the treatment of ISR. Twenty-five consecutive patients treated with VBT were compared with 29 patients who had SES deployment for ISR. Major adverse cardiac events (MACE) were defined as a combination of death from cardiac causes, nonfatal myocardial infarction, or repeat TVR. At 18 month follow-up, the MACE rate was significantly lower in the SES compared with the VBT group (14% vs 40%, P=.03). One patient in the VBT group developed late stent thrombosis (at 10 months) and died; there was no stent thrombosis in the SES group. This observational study, taken with other recent reports, offers further credence to the use of SES for ISR. The results of randomized comparisons with VBT are awaited with interest.

Underwater cytometer for in situ measurement of marine phytoplankton by a technique combining laser-induced fluorescence and laser Doppler velocimetry.

We present a new type of flow cytometer that can operate underwater for a long time, as long as days, for measuring the size distribution, concentration, and biomass of marine phytoplankton. The major improvement of the instrument over existing techniques is the elimination of sample preparation, which is achieved with a laser Doppler crossed-beam arrangement for both defining a measurement volume and measuring the speed of the particle traversing it. By simultaneously sampling the laser-induced fluorescence signal and the Doppler signals, the technique can discriminate sizes of phytoplankton.

Survival after myocardial revascularization for ischemic cardiomyopathy: a prospective ten-year follow-up study.

OBJECTIVE: The aim was to prospectively analyze all-cause mortality, predictors of survival, and late functional results after myocardial revascularization for ischemic cardiomyopathy over a 10-year follow-up. METHODS: We prospectively studied 57 patients with stable coronary artery disease and poor left ventricular ejection function (<35%), enrolled between 1989 and 1994. Stress thallium was analyzed in 37 patients to identify reversible ischemia. To avoid patients with a stunned myocardium, we excluded those with unstable angina or myocardial infarction within the previous 4 weeks. Mean age of the patients was 67 +/- 8 years, and 93% of patients were men. Mean left ventricular ejection fraction was 0.28 +/- 0.04, 50% were in Canadian Cardiovascular Society angina class III-IV, and 65% were in New York Heart Association functional class III-IV. RESULTS: Operative mortality was 1.7% (1/57). The mean left ventricular ejection fraction (0.30) at 15 months postoperatively did not change from before operation (0.28, P =.09). There were 8 deaths at 1 year and 42 deaths over the course of the study, producing a survival of 82.5% at 1 year, 55.7% at 5 years, and 23.9% at 10 years (95% confidence interval: 14.6%-39.1%). Symptom-free survival was 77.2% at 1 year and 20.3% at 10 years. The leading cause of death was heart failure in 29% (12/42). Multivariate analysis showed that large reversible defects on stress thallium were associated with improved left ventricular ejection fraction at 1 year (P =.01) but only male sex was associated with improved long-term survival (P =.036). CONCLUSIONS: Myocardial revascularization for ischemic cardiomyopathy is associated with good functional relief from the symptoms of angina initially and, to a lesser extent, heart failure. Revascularization may have the advantage of preserving the remaining left ventricular function. However, the long-term mortality remains high.