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C H Chuang

Publications and source records attributed to C H Chuang.

At least 19 recordsLinked to original sources
PubMed2006

Digital programmable light spectrum synthesis system using a digital micromirror device.

We present a digital programmable light spectrum synthesis system based on a digital micromirror device (DMD) from Texas Instruments. A DMD pattern-scanning calibration method is developed and applied to the synthesis of various infrared C-band (1530-1565 nm) spectral profiles, including a fast programmable tunable light source with a bandwidth of approximately 3.8 nm, a square profile, a sawtooth waveform, and a triangular spectrum profile. The experimental results show that the wavelength resolution of the DMD spectrum synthesis system is approximately 0.076 nm/pixel. The proposed spectrum synthesis system has a number of key advantages, including a rapid and stable performance and multichannel compatibility. The spectrum synthesis system is suitable for various applications, including pulse shaping for coherent control and harmonic generation, a tunable light source, an equalizer for erbium-doped fiber amplifiers, and a wavelength scanner.

Journal Article↗
PubMed2005

Physical and sexual violence and health care utilization in HIV-infected persons with alcohol problems.

We examined interpersonal violence and its association with health care utilization and substance use severity among a cohort of 349 HIV-infected men and women with histories of alcohol problems assessed biannually up to 36 months. Data included demographics, lifetime interpersonal violence histories, age at first violence exposure, recent violence (prior six months), substance use severity and health care utilization (ambulatory visits, Emergency Department (ED) visits, hospitalizations) and adherence to HIV medication. Kaplan-Meier survival curves estimated the proportion of subjects experiencing recent violence. Generalized estimating equation regression models evaluated the relationship between recent violence, utilization and substance use severity over time, controlling for demographics, CD4 counts and depressive symptoms. Subject characteristics included: 79% male; mean age 41 years; 44% black, 33% white and 23% other. Eighty percent of subjects reported lifetime interpersonal violence: 40% physical violence alone, and 40% sexual violence with or without physical violence. First violence occurred prior to age 13 in 46%. Twenty-four (41%) of subjects reported recent violence by 24 and 36 months, respectively. In multivariate analyses, recent violence was associated with more ambulatory visits, ED visits and hospitalizations and worse substance use severity, but not medication adherence. Due to the high incidence and associated increased health care services utilization, violence prevention interventions should be considered for HIV-infected patients with a history of alcohol problems.

Adult↗
PubMed2005

Recombinant human erythropoietin independence in chronic hemodialysis patients: clinical features, iron homeostasis and erythropoiesis.

AIMS: Recombinant human erythropoietin (r-HuEPO) is widely used to correct renal anemia in uremic patients. Interestingly, some chronic hemodialysis (HD) patients can maintain high hemoglobin level without the need of r-HuEPO. The aim of this study is to investigate clinical features, iron metabolism and erythropoiesis of these r-HuEPO-independent HD patients. METHODS: r-HuEPO independence was defined in dialysis patients as hemoglobin greater than 12 g/dl and no use of r-HuEPO for at least 6 months. An age- and sex-matched group was selected for comparison. Their underlying diseases, duration of hemodialysis therapy, efficacy of dialysis (Kt/V), normalized protein catabolic rate (nPCR) and body mass index (BMI) were recorded. Laboratory data including: hemoglobin, albumin, high sensitivity C-reactive protein, serum iron, total iron binding capacity, transferrin saturation, ferritin, intact parathyroid hormone, soluble transferrin receptor (sTfR), serum EPO, cortisol, testosterone, aluminum and leptin levels were measured. Renal sonography was also performed in each patient to evaluate renal cyst formation. RESULTS: About 2.3% of all HD patients (21/888; M : F = 18 : 3) were r-HuEPO-independent. These patients had significantly longer HD duration and higher serum EPO and sTfR levels, and lower transferrin saturation rate than dependent groups. Correlation analysis revealed that hemoglobin level strongly correlated with HD duration, serum sTfR and EPO levels. Levels of sTfR were positively related with serum EPO levels and BMI. Multivariate regression analysis showed that level of sTfR was the only independent factor related to r-HuEPO independence. CONCLUSION: R-HuEPO independence is rare among chronic hemodialysis patients. Factors contributing to this dependence are complex and multiple. Level of serum sTfR parallels erythropoiesis and is the most significant factor associated with r-HuEPO independence in chronic HD patients.

Adult↗
PubMed2005

Apoptotic markers on lymphocytes and monocytes are unchanged during single hemodialysis sessions using either regenerated cellulose or polysulfone membranes.

BACKGROUND: There is an increased rate of apoptosis of peripheral blood mononuclear cells (PBMCs) in patients undergoing hemodialysis (HD), but little is known about how different dialysis membranes may contribute to the process. We, therefore, studied the influence of two different dialysis membranes on apoptotic markers during HD. METHODS: 8 healthy controls and 8 patients on regular HD 3 times per week were enrolled in this cross-controlled study. Patients received HD using polysulfone and then regenerated cellulose dialysis membranes for one week each, sequentially. Serum was collected for C-reactive protein (CRP) detection; flow cytometry with dual antibody staining was used to measure the apoptotic markers Fas (CD95), FasL (CD 178) and TNF-R2 (CD120b) in T cells (CD3+), B cells (CD19+), and monocytes (CD14+) at 0, 15, 120 and 240 min after starting HD. We also measured total leukocyte numbers and differential white cell counts. RESULTS: Hemodialysis patients revealed lymphocytopenia, monocytopenia, higher CRP levels and higher Fas and TNF-R2 expression on lymphocytes and monocytes at baseline when compared with normal controls. Leukocyte numbers, including neutrophils, lymphocytes and monocytes, dropped significantly after 15 min of dialysis. There were no significant differences in Fas levels during hemodialysis on T and B lymphocytes or on monocytes. T lymphocyte FasL (CD 178) levels remained unchanged throughout the process. There was a significantly lower overall level of CD120b at 15 min of HD, whereas this marker was higher on monocytes after dialysis. There were no significant differences in the levels of apoptotic markers between the two membranes. CONCLUSION: Our results suggest that uremia itself contributes to PBMC apoptosis. The two different dialysis membranes used in this study did not influence apoptotic markers on PBMCs significantly, but increased TNF-R2 expression on monocytes during a single dialysis session.

Adult↗
PubMed2004

Emergency contraception: prescribing practices of general internists compared with other primary care physicians.

Primary care physicians of all specialties should be familiar with prescribing emergency contraception (EC). We conducted a mail survey of 282 randomly sampled physicians in general internal medicine (31%), family medicine (34%) and obstetrics-gynecology (35%). Experience with prescribing EC significantly differed by specialty (63% of general internists, 76% of family physicians, and 94% of obstetrician-gynecologists, p < 0.0001). Controlling for year of graduation, gender, religion and practice location, family physicians [adjusted odds ratio (OR): 2.5, 95% confidence interval (CI): 1.2-5.2] and obstetrician-gynecologists (adjusted OR: 11.2, 95% CI: 4.0-31.3) were still significantly more likely to have ever prescribed EC than general internists. Efforts to increase awareness and knowledge of EC should be aimed at general internists since they provide primary care for many reproductive age women.

Adult↗
PubMed2002

A defoaming agent should be used with pronase premedication to improve visibility in upper gastrointestinal endoscopy.

BACKGROUND AND STUDY AIMS: The study tested whether pronase can improve endoscopic visibility and alter the accuracy of the CLO test for H. pylori detection. PATIENTS AND METHODS: A total of 160 patients were randomly assigned to receive one of five premedications for endoscopy: group A: dimethylpolysiloxane (DMPS) alone; group B: DMPS plus water (up to 100 ml); group C: pronase only, with 100 ml water; group D: pronase and sodium bicarbonate plus water up to 100 ml; group E: pronase, sodium bicarbonate, and DMPS, plus water up to 100 ml. Endoscopists, who were unaware of the premedication method administered, assessed visibility scores (range 1 - 4) for the antrum, lower gastric body, upper gastric body, and fundus. The higher the score, the less clear the visibility. The sum of scores from the four locations was defined as the total visibility score. A CLO test was also done during the endoscopy. One week after their endoscopy, patients in groups C, D, and E were scheduled for a (13)C-urea breath test (UBT). RESULTS: Group E patients had a significantly lower total visibility score than those in the other four groups ( P < 0.05). Groups C and D had higher total visibility scores than the other three groups ( P < 0.05). The scores did not significantly differ between groups A and B. Based on the UBT results, the sensitivity and specificity of the CLO test were 92.6 % and 96.2 %, respectively. CONCLUSIONS: Premedication as in group E provided the clearest endoscopic visibility. Without the application of DMPS, pronase alone cannot improve endoscopic visibility. Pronase does not influence H. pylori identification using the CLO test.

Adult↗
PubMed2001

Solid-state trans-cis isomerization of captopril determined by thermal Fourier transform infrared (FT-IR) microspectroscopy.

Thermal Fourier transform infrared (FT-IR) microspectroscopy was used to investigate the conformational isomerization of captopril in the solid state. The result indicates that the IR peak intensity of captopril for original bands decreased dramatically at 102 degrees C, but for new bands it increased with the rise of temperature. The frequency of C=O stretching mode for carboxylic acid and for amide was located at a higher wavenumber of 1747 cm(-1) and at a lower frequency of 1591 cm(-1) as compared with the general compound, suggesting the existence of trans isomer of captopril in the solid state by intramolecular hydrogen bonding. Beyond 102 degrees C, several new bands at 1720, 1645, and 1610 cm(-1) were observed with the rise of temperature, indicating the coexistence of a cis isomer. However, the cis isomer could transform gradually to the trans isomer after cooling. The thermodynamics of equilibrium mixture of cis/trans isomers were also studied. The trans isomer was more stable than the cis isomer, but the cis isomer was favored at the higher temperature.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Ranitidine bismuth citrate or omeprazole-based triple therapy for Helicobacter pylori eradication in Helicobacter pylori-infected non-ulcer dyspepsia.

AIM: To test the eradication rate of Helicobacter pylori by ranitidine bismuth citrate-based triple therapy, and evaluate the symptomatic response of Helicobacter pylori eradication therapy for non-ulcer dyspepsia. METHODS: A total of 59 consecutive Helicobacter pylori infected non-ulcer dyspepsia patients were randomly selected to receive either one of two triple therapy regimens, including metronidazole, amoxycillin plus ranitidine bismuth citrate (RAM group) or omeprazole (OAM group). To determine the success of eradication, patients underwent the 13C-urea breath test, 6 weeks and one year after treatment. The dyspeptic symptom scores were also assessed at the time of enrolment, 6 weeks and one year after treatment. RESULTS: Per-protocol and intention-to-treat eradication rates were 77.7% and 70% in RAM group and 83.8% and 68.9% in OAM group (p = non significant). At both the 6th week and at the first year after treatment, the mean symptom scores were lower than pre-treatment scores in the study population, regardless of whether treatment was successful or not. However, patients, whether eradicated successfully or not-eradicated, presented similar 6-week and 1-year scores. CONCLUSIONS: One-week RAM triple therapy, which is cheaper than the OAM regimen, is a relatively effective alternative regimen for Helicobacter pylori eradication in Taiwanese. Triple therapy for Helicobacter pylori eradication was not the whole management for the relief of dyspeptic symptoms of non-ulcer dyspepsia patients.

Adult↗
PubMed2001

Pretreatment gastric histology is helpful to predict the symptomatic response after H. pylori eradication in patients with nonulcer dyspepsia.

This study aimed to test whether pretreatment gastric pathology in H. pylori-infected nonulcer dyspepsia (HpNUD) patients is relevant to and predictive of the symptomatic response after H. pylori eradication. Anti-H. pylori triple therapy was administered to 250 HpNUD patients, enrolled as the therapy group. In addition, 60 patients were enrolled as the control group, in which omeprazole was an alternatives to the triple therapy. Pretreatment gastric histology was evaluated thoroughly by the updated Sydney system. A [13C] urea breath test was also performed to evaluate the H. pylori eradication two months and 12 months later. For each patient, the baseline, month 2, and month 12 symptom scores were assessed for the month 2 or month 12 residual symptom ratio (RSR-2m or RSR-12m), calculated from: 100% x month 2 or month 12 score/baseline score. Based on either RSR-2m or RSR-12m, patients were categorized as good response (RSR < 50%), moderate response (50-70%), and poor response (> 70%) subgroups in both therapy and control groups to define the short-term and long-term symptomatic responses. Patients with successful H. pylori eradication in the therapy group showed a higher incidence of good symptomatic response (RSR < 50%) than those from the control group (month 2: 30.3 vs 12%, P < 0.05; month 12: 34.7 vs 17.1%, P < 0.05). Univariate and multivariate analysis disclosed that patients with a higher acute inflammation score (AIS) and the lowest incidence of lymphoid follicles (LF) at pretreatment gastric histology are predisposed to having a good symptom response after H. pylori eradication (P < 0.05). For HpNUD patients who have an AIS of more than three and an absence of LF at gastric histology, more than 85% had good short-term (month 2) and long-term (month 12) symptomatic relief after H. pylori eradication. In conclusion, nearly 30% of HpNUD patients can obtain symptomatic relief following H. pylori eradication. The pretreatment gastric histology of HpNUD can be helpful to monitor the symptomatic response after H. pylori eradication.

Adult↗
PubMed2000

Carbon urea breath test is not as accurate as endoscopy to detect Helicobacter pylori after gastrectomy.

BACKGROUND: This study was conducted to determine (1) whether Helicobacter pylori infection decreases in conjunction with time elapsed after gastrectomy and (2) the diagnostic efficacy of (13)C urea breath test (UBT) for H pylori in patients after gastrectomy. METHODS: From January 1997 to June 1998, 86 patients who had undergone gastrectomy and 180 patients with dyspepsia without gastrectomy were enrolled. A UBT for the analysis of excess (13)CO(2)/(12)CO(2) ratio (ECR) was obtained for each patient. Each patient also underwent endoscopy to obtain gastric biopsies for histology and H pylori culture. The presence of H pylori by either histology or culture served as the standard to test the efficacy of UBT. The 86 patients with a prior gastrectomy were categorized into 3 subgroups (I, less than 1 year; II, 1 to 3 years; III, greater than 3 years), according to the interval between surgery and UBT. The initial H pylori status of these 86 patients was determined by histologic evaluation of the resected stomach. RESULTS: At trial initiation, the postgastrectomy group had a lower H pylori infection rate (52.3%) as compared with the dyspeptic control group (80%). The initial H pylori status among subgroups I, II, and III was similar. There was a trend for the presence of H pylori in the stomach to decrease with increasing time elapsed after surgery (I to III: 68.8%, 48.3%, 36%, respectively; p < 0.05). The maximum UBT sensitivity and specificity achieved were 82.2% and 87.8% in the gastrectomy group and 97.2% and 96.3% in the dyspeptic group, with cutoff points of 2.5 and 4.0, respectively. CONCLUSION: The prevalence of H pylori diminishes with time elapsed after gastrectomy. UBT for detection of H pylori is more effective in patients without prior gastrectomy than in patients who have undergone gastrectomy and is less effective than endoscopy for patients who have had a gastrectomy.

Biopsy↗
PubMed1999

Biochemical markers for assessment of bone metastases in patients with breast cancer.

Breast cancer commonly metastasizes to bones, producing both osteolytic and osteoblastic deposits. Different markers for quantitative determination of bone turnover have been developed to evaluate bone metastases of breast cancer. The urinary deoxypyridinoline (Dpd), a crosslink product of collagen molecules found in bone and excreted in urine during bone degradation, and bone specific alkaline phosphatase (B-ALP), an isoenzyme localized in the membrane of osteoblasts and released in circulation during bone formation, were recently described as a group of markers of bone turnover in metastatic cancer. The urinary Dpd/creatinine (Cre) ratios and the serum B-ALP activity were determined in the samples from 148 patients who suffered from breast cancer (BC patients) with or without bone metastases, and 42 healthy women. For comparison, other biochemical markers, e.g. carcinoembryonic antigen (CEA), CA15-3, tissue polypeptide antigen (TPA), tissue polypeptide specific antigen (TPSA), and total alkaline phosphatase (T-ALP) in these samples were also evaluated. The results showed that there was a significant difference in urinary Dpd/Cre ratio between the control group and the patients with breast cancer (BC group) (mean +/- S.D., 5.69 +/- 1.26 vs. 8.19 +/- 3.95 nM/mM, P < 0.05). However, there was no significant difference between their B-ALP activities in the two groups. In addition, the BC patients with bone metastases showed elevated urinary Dpd/Cre ratios and B-ALP activities and ratios of (Dpd/Cre)/B-ALP in compare with BC patients without bone metastases (P < 0.05). Meanwhile, the urinary Dpd/Cre ratios (10.50 +/- 5.04 nmol/mmol) in the advanced stage of BC patients were higher than those in an early stage (7.45 +/- 3.23 nmol/mmol) (P < 0.05), but their serum B-ALP activities increased only in stage IV (P < 0.05). The urinary Dpd/Cre ratios also increased progressively according to the degree of bone metastases (P < 0.05), but their serum B-ALP activities only increased in severe bone metastases (P < 0.05). The results showed that the increase of a bone osteolytic activity took place earlier than that of a bone osteoblastic activity in the metastatic BC patients. In compare with other conventional markers, the best diagnostic efficiency of biochemical markers, analyzed by step wise discriminate analysis, was provided by CEA followed by Dpd/Cre ratio, CA15-3, TPA, TPSA, B-ALP and T-ALP. We conclude that showed the urinary Dpd/Cre ratio was a useful tumor marker to evaluate breast cancer with bone metastases.

Adult↗
PubMed1999

Mondor's disease in the breast.

Mondor's disease, superficial thrombophebitis of the breast, is an uncommon self-limiting condition. Surgical procedures and trauma were the common known causes. The objective of this study was to evaluate the incidence of Mondor's disease in different breast operations in lower risk of breast cancer area over a 6-year period and to identify its causes, clinical features, related surgical factors and associated breast cancer. Eighty-four cases of Mondor's disease were obtained from 9657 new patients in the breast clinic of Kaohsiung Medical University Hospital between January 1991 and December 1996. The incidence per year was close (0.84%-0.96%) although the number has been increasing each year. In 23 cases, no definite cause was diagnosed, whereas in 61 cases, the disorder was secondary because the pathogenesis could be discerned. The identified causes included forty-three cases caused by breast surgery, two cases associated with breast cancer and sixteen cases with other benign causes. Although the incidence did not differ significantly between breast surgery (0.95%) and non-surgical causes (0.79%), the highest incidence, 1.52%, occurred when excision through circumareolar incision and tunnel procedure for cosmesis (25 cases in 1634 excisions) were used, and the lowest 0.69% when excisions through direct incision (14 cases in 2004 excisions) were performed. (P < 0.05) The other incidence rates were 1.56% in breast conserving surgery which is higher than 0.37% following mastectomy. The incidence of the disease was higher (4.28%) when the distance of the breast lesion was more than 3 cm from the areolar edge, compared to 1.20% for the 2 cm group and 0.32% for the 1 cm group (P < 0.05) in tunnel procedures. The incidence of Mondor's disease during breast surgery was not significantly different in different breast quardrants. Although Mondor's disease is a benign, self-limiting condition, a high incidence developed in the excision biopsy through circumareolar incision with tunnel procedure when the distance from the breast lesion to the areolar edge was more than 3 cm. To prevent this complication, the tunnel procedure in breast biopsy should be avoided. The incidence of Mondor's disease associated with breast cancer was low (2.4%) in the lower-incidence breast cancer area from this series, but awareness of the condition is recommended.

Adolescent↗
PubMed1997

Laser photoablation of experimental post-infarction ventricular tachycardia guided by three dimensional activation mapping.

BACKGROUND AND OBJECTIVE: The purpose of this study was to evaluate the efficacy of epicardially delivered laser energy to ablate induced ventricular tachycardia in a post-infarction canine model. STUDY DESIGN/MATERIALS AND METHODS: In 13 canines, the left anterior wall myocardial infarction was created. Five days later, 240 plunged electrodes were inserted into the heart. Three-dimensional ventricular activation sequences were analyzed on line by a computerized mapping system. RESULTS: Sixteen sustained monomorphic ventricular tachycardias were reproducibly induced in 10 canines. Epicardially contacted Nd:YAG laser irradiated the areas of the final pathway in macro-reentrant activation and the impulse origin in focal excitation. Linear photocoagulation lesions (11-16 x 50-72 mm) were created. Seven macro-reentrant circuits and six of nine focal origins were eliminated (success rate 81%). Pathology showed that laser photocoagulation involved all surviving subepicardial and intramural fibers. CONCLUSION: Epicardially delivered laser energy in conjunction with electrical activation mapping has a high probability of ablating post-infarction ventricular tachycardia.

Animals↗
PubMed1995

Selective coagulation necrosis of canine adventitia and media induces extracellular matrix accumulation without neointima formation.

Endothelial cell injury, the disruption of the internal elastic membrane and medial damage represent important stimuli for the development of a neointima. It is unclear whether selective adventitial and medial injury also induce neointima formation. Incremental argon laser energies (11.4-180 J/cm2) were applied to the external surface of dog femoral arteries to evaluate the vascular repair of acute adventitial or medial necrosis without injury of the intima. The animals were sacrificed either one hour after the initial procedure or after an 8 week follow up period for histologic examination. Acute, and mild to moderate necrosis of the arterial wall was found above 50 J/cm2. Ablation of the internal elastic membrane or mural thrombi was not detected. Eight weeks after photocoagulation with laser energies above 50 J/cm2, a significant increase in mean wall thickness of the media was observed. The medial thickening was characterised by an accumulation of extracellular matrix and a loss of smooth muscle cells. Necrosis of adventitia and media resulted in arterial wall thickening without neointima formation. It is concluded that, in dogs, an acute, selective injury of adventitia and media stimulates the production of extracellular matrix and not the proliferation of cells. Smooth muscle cell migration and subsequently neointima formation are induced by viable smooth muscle cells when blood-borne stimuli are available.

Analysis of Variance↗
PubMed1995

Computerized three-dimensional activation mapping study of spontaneous ventricular arrhythmias during acute myocardial ischemia in dogs. Evidence against macroreentrant mechanism.

This study was undertaken to investigate the activation patterns of spontaneous ventricular arrhythmias during acute myocardial ischemia in dogs. In 14 open-chest dogs, the left anterior descending coronary artery was occluded for 2 hours. Three-dimensional activation maps were derived from 240 bipolar sites by insertion of 60 plunge needle electrodes into both ventricles and the septum. Global ventricular activation sequences were displayed in five planes in 10 dogs, whereas the high density regional activation maps of the anterior wall were displayed in four layers in 4 dogs. Three-dimensional activation maps of 95 sinus beats, 82 premature ventricular complexes (PVCs), and 210 beats of ventricular tachycardia (VT) were analyzed. Sinus beats had a uniform activation pattern with total ventricular activation times measuring 42 +/- 4 ms and 67 +/- 8 ms during baseline and ischemia, respectively (P < .05). The PVCs and VTs originated from the subendocardial and intramural layers, and activation patterns invariably suggested focal excitation. Macroeentry was not operative because (1) the breakthrough sites were always remote from the latest activation areas; (2) there was no electrical activity bridging the gap between the termination of a beat and initiation of the subsequent beat; and (3) impulse conduction was not sufficiently delayed to reexcite the area of impulse origin even though functional conduction block was frequently present. In high-density regional activation maps, fragmented activity spanning the diastolic interval was never found. In conclusion, spontaneously occurring PVCs and VTs during acute myocardial ischemia in dogs display focal excitation with no evidence of macroreentry.

Animals↗
PubMed1995

Myocardial temperatures during in vivo endocardial Nd:YAG laser irradiation.

To determine safety and efficacy of neodymium:YAG laser irradiation of the endocardium, temperatures at both the epicardium and the endocardium were recorded for thermal damage evaluation. A total of 48 coagulation lesions were created at power settings of 20 and 30 W in 20 open chest dogs by transcatheter endocardial laser irradiation. Tissue temperatures were monitored by epicardial thermography (Tepi), and by endocardial thermocouples at the catheter tip (Tprox) and 4 mm below the endocardial surface (Tdist). In group I the optical fiber extended 1 mm from the catheter and irradiation times ranged from 3 to 60 sec. Tepi reached > or = 57 degrees after a weighted average of 5 sec of laser irradiation (n = 44). In group II the fiber was retracted 1 mm from the catheter tip, and irradiation times were 100 to 150 sec. Tepi reached > or = 57 degrees C after a weighted average of 30 sec (n = 4). Blood vessels were recognized as heat sinks until coagulation occurred. Lesion volume showed a proportional increase with total delivered energy. From the observed timeframes in epicardial temperature rise it is suggested that total direct light absorption at the epicardium was the main contribution to Tepi, and the Nd:YAG laser can efficiently create transmural lesions. The epicardial temperatures remained below 80 degrees C in combination with the constant movement of the epicardial wall suggested safety from thermal damage to the ambient organs.

Animals↗
PubMed1994

Ultrasonic characterization of myocardial photocoagulation lesion size in vivo during Nd:YAG laser irradiation.

Endocardial coagulation lesions were created using transcatheter continuous-wave Nd:YAG laser irradiation. Ultrasound monitoring of thermal lesion dimensions was performed using 7.5-MHz and 10-MHz transducers directly from the epicardial surface in short-axis configuration (group A) or through the chest wall (group B). A total of 33 lesions were created in 10 dogs at energy levels ranging from 300 J to 1000 J. Mean histological lesion width (HW) compared with ultrasonically determined mean width (UW) showed that the differences (mean +/- standard deviation) in group A (UW - HW) was = 1.14 +/- 0.8 mm, which was not statistically significantly different from zero. In group B, (UW - HW) = 2.04 mm +/- 0.7 mm (p < .05), which was statistically significantly different from zero. Mean histological depth (HD) differentially related to ultrasound mean depth (UD) for group A and B combined showed (UD - HD) = -0.19 mm +/- 0.46 mm, not statistically significantly different from zero. The frequency distribution for width in group A showed magnitude of UW-HW > 3 mm in 32% of cases. In group B magnitude of UW-HW > 3 mm in 15%, whereas ultrasound width was larger than histology in 75% of the cases. For depth, magnitude of UD-HD > 3 mm in 15% of cases. With further refinement of the technique, ultrasonic tissue characterization may become a useful adjunct to monitoring lesion dimensions during transcatheter laser photocoagulation.

Animals↗