Cancer effect on periprocedural thromboembolism and bleeding in anticoagulated patients

BACKGROUND

Patients with active cancer are often on chronic anticoagulation and frequently require interruption of this treatment for invasive procedures. The impact of cancer on periprocedural thromboembolism (TE) and major bleeding is not known.

PATIENTS AND METHODS

Two thousand one hundred and eighty-two consecutive patients referred for periprocedural anticoagulation (2484 procedures) using a standardized protocol were followed forward in time to estimate the 3-month incidence of TE, major bleeding and survival stratified by anticoagulation indication. For each indication, we tested active cancer and bridging heparin therapy as potential predictors of TE and major bleeding.

RESULTS

Compared with patients without cancer, active cancer patients (n=493) had more venous thromboembolism (VTE) complications (1.2% versus 0.2%; P=0.001), major bleeding (3.4% versus 1.7%; P=0.02) and reduced survival (95% versus 99%; P<0.001). Among active cancer patients, only those chronically anticoagulated for VTE had higher rates of periprocedural VTE (2% versus 0.16%; P=0.002) and major bleeding (3.7% versus 0.6%; P<0.001). Bridging with heparin increased the rate of major bleeding in cancer patients (5% versus 1%; P=0.03) without impacting the VTE rate (0.7% versus 1.4%, P=0.50).

CONCLUSIONS

Cancer patients anticoagulated for VTE experience higher rates of periprocedural VTE and major bleeding. Periprocedural anticoagulation for these patients requires particular attention to reduce these complications.

Immediate intraocular pressure changes following intravitreal injections of triamcinolone, pegaptanib, and bevacizumab

PURPOSE

To assess the intraocular pressure (IOP) changes, within the first 30 min after intravitreal injection of 0.1 ml (4 mg) triamcinolone, 0.09 ml (0.3 mg) pegaptanib, and 0.05 ml (1.25 mg) bevacizumab.

METHODS

Records of patients who received intravitreal triamcinolone, pegaptanib, and bevacizumab and who had their IOP measured post-injection were reviewed.

RESULTS

A total of 212 injections were performed (76 bevacizumab in 63 patients, 42 triamcinolone in 41 patients, 94 pegaptanib in 74 patients). At 10 min, over 87% of eyes receiving each drug had an IOP of less than 35 mmHg. Three of the 42 eyes receiving intravitreal triamcinolone were treated with IOP-lowering drops for pressures of 44, 46, and 60 mmHg. No patients treated with intravitreal bevacizumab or pegaptanib received IOP-lowering drops. The number of eyes in each injection group that had an IOP rise >10 mmHg within 30 min after injection was 27.6% of eyes receiving bevacizumab, 33.3% of eyes receiving triamcinolone, and 36.2% of eyes receiving pegaptanib. At 10 min, eyes with glaucoma were less likely to have an IOP<35 mmHg, but this difference became less marked with time.

CONCLUSION

In our series, most patients receiving intravitreal injections did not require IOP-lowering drops after injection, and none required a paracentesis.

Role of programmed ventricular stimulation and implantable cardioverter defibrillators in patients with idiopathic dilated cardiomyopathy and syncope

The aim of this study was to evaluate the role of programmed ventricular stimulation and ICDs in patients with idiopathic dilated cardiomyopathy and syncope. Between 1990 and 1998, 54 (mean age 67+/-11 years, 76% men) patients presented with idiopathic dilated cardiomyopathy and syncope. An electrophysiological study was done in 37 of the 54 patients: 10 had inducible sustained monomorphic ventricular tachycardia, 12 had conduction system disease or neurocardiogenic syncope, and 15 had a normal study. Overall, 17 patients received an ICD, 15 patients received a pacemaker, and 22 patients received no device. Nine of the 15 patients with a negative electrophysiological study eventually received an ICD: 3 because they were considered high risk and 6 because of recurrent syncope or presyncope. In the 17 patients who received an ICD, incidence of appropriate shocks at 1 and 3 years was 47% and 74%, respectively, in the inducible sustained monomorphic ventricular tachycardia group, and 40% and 40%, respectively, in the group without inducible sustained monomorphic ventricular tachycardia (P = 0.29, log-rank test). In conclusion, programmed ventricular stimulation is not useful in risk stratification of patients with idiopathic dilated cardiomyopathy and syncope and may delay necessary ICD implantation.

Comparison of Chen Medium and Optisol-GS for human corneal preservation at 4 degrees C: results of transplantation

PURPOSE

To compare results after transplantation of donor corneas stored in Chen Medium (containing beta-hydroxybutyrate without sodium bicarbonate or chondroitin sulfate) to corneas stored in Optisol-GS medium (containing sodium bicarbonate and 2.5% chondroitin sulfate).

METHODS

We performed 32 consecutive penetrating keratoplasties with donor corneas stored at 4 degrees C in either Chen Medium or Optisol-GS by random assignment. Corneal thickness measurements were made at 1 day, 1 week, 3 weeks, 2 months, and 1 year postkeratoplasty. Specular microscopic images of the donor endothelium were obtained at the beginning of storage and 2 months and 1 year postkeratoplasty. The percentage of intact epithelium 1 day after keratoplasty and the graft epithelialization time were estimated by the surgeons. Donor rim cultures were performed.

RESULTS

No statistically significant differences in corneal thickness or endothelial cell loss between the corneas stored in the two media were found at any time, although differences of less than 12% cell loss or 0.09-mm thickness at 2 months or less than 25% cell loss or 0.10-mm thickness at 1 year could not be excluded with 90% certainty in this small series. The mean percentages of intact graft epithelium on day 1, 64% for Chen Medium and 65% for Optisol-GS, were not significantly different. Endothelial cell density 2 months postkeratoplasty was significantly decreased for corneas stored in both media. Endothelial cell loss at 2 months was directly correlated with storage time in both media.

CONCLUSIONS

After keratoplasty, no statistically significant differences in corneal thickness, epithelial survival, and endothelial cell loss were found between corneas stored in Chen Medium and Optisol-GS. Endothelial cell loss at 2 months was significantly correlated with storage time in both media.

Keratometric results during the first year after keratoplasty: adjustable single running suture technique versus double running suture technique

BACKGROUND AND OBJECTIVE

To compare the 3-month and 1-year postoperative keratometric results in a retrospective sequential series of corneal grafts performed with either a double running suture technique or an adjustable single running suture technique.

MATERIALS AND METHODS

Keratometry values obtained 3 months and 1 year after penetrating keratoplasty, when sutures were still present, were compared between 31 grafts with double running sutures and 27 grafts with single running sutures, 15 of which had been adjusted postoperatively.

RESULTS

No significant difference in mean keratometry between the 2 groups was found either 3 months or 12 months after keratoplasty. Mean keratometric astigmatism was significantly less in the single running group at both 3 months (2.2 +/- 1.9 vs 4.5 +/- 2.8, mean +/- SD, P <0.001) and 12 months (3.0 +/- 2.2 vs 4.2 +/- 2.1, P = 0.03). Within groups, there was no significant change from 3 months to 12 months in either mean keratometry or keratometric astigmatism.

CONCLUSION

The single running suture technique, with postoperative adjustments, produced less keratometric astigmatism during the first postoperative year, when sutures were still in place.

Gender differences and temporal trends in clinical characteristics, stress test results and use of invasive procedures in patients undergoing evaluation for coronary artery disease

OBJECTIVES

This study examined gender differences and temporal changes in the clinical characteristics of patients referred for nuclear stress imaging, their imaging results and subsequent utilization of coronary angiography and revascularization.

BACKGROUND

Gender bias may influence resource utilization in patients with coronary artery disease (CAD). No study has analyzed gender differences and time trends in patients referred for noninvasive testing and subsequent use of invasive procedures.

METHODS

Between January 1986 and December 1995, 14,499 patients (5,910 women and 8,589 men) without established CAD underwent stress myocardial perfusion imaging. The clinical characteristics, imaging results, coronary angiograms and revascularization outcomes were compared in women and men over time.

RESULTS

The mean pretest probability of CAD was lower in women (45%) than in men (70%) (p < 0.001). More women (69%) than men (42%) had normal nuclear images (p < 0.001). Men (17%) were more likely than women (8%) to undergo coronary angiography (p < 0.001). Male gender was independently associated with referral for coronary angiography (multivariate model: chi-square = 16, p < 0.001) but was considerably weaker than the imaging variables (summed reversibility score: chi-square = 273, p < 0.001). Revascularization was performed in more men (46% of the population undergoing angiography) than women (39%) (p = 0.01), but gender was not independently associated with referral to revascularization. There were no significant differences in clinical, imaging or invasive variables between the genders over time.

CONCLUSIONS

There was little evidence for a bias against women in this study. Women were somewhat less likely to undergo coronary angiography but were referred for stress perfusion imaging more liberally. Practice patterns remained constant over this 10-year period.

Predictors of macrovascular disease in patients with type 2 diabetes mellitus

OBJECTIVE

To assess the importance of classic and nonclassic risk factors in the development of coronary artery disease (CAD) or cerebrovascular disease (CVD) in patients with type 2 diabetes mellitus (DM).

PATIENTS AND METHODS

In this community-based, prospective cohort study, quantitative measurements for cholesterol, triglycerides (TGs), glucose, and lipoprotein(a) detected as a sinking pre-beta-lipoprotein band on electrophoresis were obtained from 1968 through 1982 from 449 patients who were free of CAD and CVD but had type 2 DM. Demographic data and covariables obtained were age, body mass index, duration of diabetes, sex, smoking, and hypertension. The relationship of individual continuous factors to the development of CAD and CVD as well as multivariate models were evaluated with use of the Cox proportional hazards model. The primary outcome was to determine which risk factors are associated with development of CAD or CVD in patients with type 2 DM.

RESULTS

After a mean follow-up of 13 years, 216 CAD and 115 CVD events had developed. The hazard ratio estimates with 95% confidence intervals (CIs) for CAD after multivariate analysis were significant for age, 1.45 (95% CI, 1.27-1.67); fasting glucose levels at enrollment, 1.63 (95% CI, 1.17-2.25); smoking, 1.45 (95% CI, 1.10-1.91); and TGs, 1.49 (95% CI, 1.15-1.92). The hazard ratio estimates for CVD were significant for age, 1.95 (95% CI, 1.59-2.38); hypertension, 1.89 (95% CI, 1.30-2.74); fasting glucose levels at enrollment, 1.69 (95% CI, 1.06-2.70); and smoking, 1.57 (95% CI, 1.07-2.30).

CONCLUSION

In diabetic patients, age, fasting glucose levels, smoking, and TG levels are independent risk factors for development of CAD events. Age, hypertension, glucose, and smoking predicted development of CVD events.

The long-term outcome of glaucoma filtration surgery

PURPOSE

To determine the long-term outcome of glaucoma filtration surgery in preserving vision. Visual loss from progressive glaucomatous damage and from complications of surgery, both short and long term, were included.

METHODS

A retrospective, community-based, longitudinal study of residents of Olmsted County, Minnesota, who were newly diagnosed with open-angle glaucoma between 1965 and 1980 and underwent filtration surgery in these or subsequent years through 1998. Intraocular pressure (IOP), visual acuity, visual fields, and progression to legal blindness were monitored. Kaplan-Meier analysis was used to determine the cumulative probabilities of changes in these parameters.

RESULTS

73 eyes of 49 patients underwent conventional filtration surgery. Analysis of the first eye having surgery revealed a mean preoperative IOP of 27.6 +/- 8.5 mm dropping to 16.7 +/- 5.6 mm at year one, and remaining in this range throughout follow-up (14.7 +/- 3.0 mm at 10 years; with or without use of medications). The probability of progression to blindness was 46% at 10 years after surgery, as calculated by Kaplan-Meier analysis. Eyes going blind had a postoperative IOP equal to or lower than those not becoming blind (14.0 +/- 4.4 vs. 15.4 +/- 3.0 at postoperative year 10). Eyes going blind had more advanced field loss at the time of surgery, with scotomas above and below the horizontal axis, than eyes not going blind, which had scotomas in only one hemifield. Three patients developed late bleb leaks; two patients developed endophthalmitis. The probability of undergoing cataract surgery was 37% by 10 years postoperatively, which did not differ significantly from the cohort of patients not undergoing surgery at a comparable time point.

CONCLUSIONS

Filtration surgery was associated with a 54% probability of preservation of vision from progression to legal blindness at 10 years after surgery. Patients becoming blind had more advanced field loss at the time of surgery; IOP was similar between those going blind and those retaining vision.

Prediction of severe coronary artery disease and long-term outcome in patients undergoing vasodilator SPECT

BACKGROUND

Vasodilator perfusion imaging has not been extensively evaluated for predicting severe coronary artery disease (CAD) or long-term prognosis.

METHODS AND RESULTS

The goals of this study were to develop a model to predict left main/3-vessel CAD in patients undergoing vasodilator thallium 201 imaging and coronary angiography (angiographic population) and to test the long-term prognostic value of this model in a separate cohort of patients who were not referred for angiography (prognostic population). In the angiographic population (n = 653) the chi2 value of the clinical model (containing the variables age, sex, and prior myocardial infarction) in the prediction of severe CAD was 32. The addition of 3 vasodilator Tl-201 variables (magnitude of ST-segment depression, summed reversibility score, and increased lung uptake) increased the model chi2 value to 114 (P <.001). Only 9% of predicted low-risk patients versus 57% of predicted high-risk patients had severe CAD. In the prognostic population (n = 521) survival rates free of cardiac death or myocardial infarction at 7 years were 91%, 73%, and 51%, respectively, for patient groups predicted to be at low, intermediate, and high risk of severe CAD (P <.001).

CONCLUSIONS

Clinical and vasodilator Tl-201 variables can accurately predict the risk of severe CAD. Stress Tl-201 variables add incremental information to clinical variables. The same model also predicts patient outcome.

Estimated incidence of open-angle glaucoma in Olmsted County, Minnesota

PURPOSE

To determine the incidence rates of open-angle glaucoma (OAG) in Olmsted County, MINNESOTA:

DESIGN

Retrospective population-based estimate of incidence.

PARTICIPANTS

From the medical histories of 60,666 residents of Olmsted County, Minnesota, who had ocular diagnoses during the study period, 114 subjects with newly diagnosed OAG were identified.

METHODS

The database of the Rochester Epidemiology Project was used to identify all Olmsted County residents with a coded diagnosis of OAG, glaucoma suspect, or ocular hypertension during the period 1965 to 1980. Subjects newly diagnosed with and treated for OAG who also had documented clinical evidence of elevated intraocular pressure, optic nerve damage, and/or visual field loss consistent with glaucoma were included as incident cases. Population data for Olmsted County were drawn from United States Census data. Crude incidence data were adjusted to the age and gender distribution of the 1990 United States white population.

MAIN OUTCOME MEASURES

Estimated incidence rates of OAG.

RESULTS

The overall age- and gender-adjusted annual incidence rate of OAG in a predominantly Caucasian population is conservatively estimated to be 14.5 per 100,000 population. The rates increased with age from 1.6 in the fourth decade of life to 94.3 in the eighth decade. There was no significant difference in incidence by gender. The average annual rate of OAG in the last 2 years of the study was 27.7 compared with 12.3 before 1979. This difference is suggestive of the effect of the introduction of a new medical therapy (timolol) for OAG during the last 2 years.

CONCLUSIONS

The incidence rates of OAG increase markedly with advancing age, and screening efforts should be targeted at both men and women in the older age groups. The advent of new diagnostic and therapeutic modalities can have an effect on incidence rates.

Long-term survival after ablation of the atrioventricular node and implantation of a permanent pacemaker in patients with atrial fibrillation

BACKGROUND

In patients with atrial fibrillation that is refractory to drug therapy, radio-frequency ablation of the atrioventricular node and implantation of a permanent pacemaker are an alternative therapeutic approach. The effect of this procedure on long-term survival is unknown.

METHOD

We studied all patients who underwent ablation of the atrioventricular node and implantation of a permanent pacemaker at the Mayo Clinic between 1990 and 1998. Observed survival was compared with the survival rates in two control populations: age- and sex-matched members of the Minnesota population between 1970 and 1990 and consecutive patients with atrial fibrillation who received drug therapy in 1993.

RESULTS

A total of 350 patients (mean [+/-SD] age, 68+/-11 years) were studied. During a mean of 36+/-26 months of follow-up, 78 patients died. The observed survival rate was significantly lower than the expected survival rate based on the general Minnesota population (P<0.001). Previous myocardial infarction (P<0.001), a history of congestive heart failure (P=0.02), and treatment with cardiac drugs after ablation (P=0.03) were independent predictors of death. Observed survival among patients without these three risk factors was similar to expected survival (P=0.43). None of the 26 patients with lone atrial fibrillation died during follow-up (37+/-27 months). The observed survival rate among patients who underwent ablation was similar to that among 229 controls with atrial fibrillation (mean age, 67+/-12 years) who received drug therapy (P=0.44).

CONCLUSIONS

In the absence of underlying heart disease, survival among patients with atrial fibrillation after ablation of the atrioventricular node is similar to expected survival in the general population. Long-term survival is similar for patients with atrial fibrillation, whether they receive ablation or drug therapy. Control of the ventricular rate by ablation of the atrioventricular node and permanent pacing does not adversely affect long-term survival.

Assessment of the exercise electrocardiogram in women versus men using tomographic myocardial perfusion imaging as the reference standard

The exercise electrocardiogram (ECG) is widely believed to be less accurate in women, primarily due to a high prevalence of false-positive tests. The purpose of this study was to examine the relative accuracy of the exercise ECG in women versus men in 8,671 patients (3,213 women, 5,458 men) using myocardial perfusion imaging as the reference standard. More women (14%) than men (10%) had a false-positive ECG (p <0.001), but the absolute difference was relatively small. The false-negative rate was considerably lower in women (17% vs 32%, p <0.001). Compared with men, women had lower test sensitivity (30% vs 42%, p <0.001) and positive predictive value (34% vs 70%, p <0.001) but higher specificity (82% vs 78%, p = 0.002), negative predictive value (78% vs 52%, p <0.001), and accuracy (69% vs 58%, p <0.001). In patients with a false-negative exercise ECG, "high-risk" scans were less prevalent in women (12% vs 19%, p <0.001). In the smaller subset of patients referred for coronary angiography (205 women, 838 men), the false-positive electrocardiographic rate was again higher in women (13% vs 7%, p = 0.003), but neither specificity (69% vs 74%, p = NS) nor accuracy (60% vs 66%, p = NS) was different between the sexes. Thus, the percentage of patients with a false-positive exercise ECG was higher in women than men but low in absolute terms (<15%) for both sexes. Test specificity was not lower in women. These results suggest that gender should not be a major determinant for selecting stress imaging over standard treadmill testing.

Increased corneal thickness in patients with ocular hypertension

BACKGROUND

Central corneal thickness greater than 0.520 mm causes true intraocular pressure to be overestimated when the technique of applanation tonometry is used to measure intraocular pressure.

OBJECTIVE

To compare the corneal thickness measurements of patients enrolled in a study of ocular hypertension with those of age-matched control subjects with normal intraocular pressure.

METHODS

Central corneal pachymetry using an optical pachymeter was performed on each study subject (n = 55) at baseline and in an independent sample of control subjects. A 2 sample, 2-tailed T test was used to compare the 2 populations.

RESULTS

The patients with ocular hypertension had significantly higher mean corneal thickness measurements (mean +/- SD, 0.594 +/- 0.037 mm) than the control group (0.563 +/- 0.027 mm) (P<.001).

CONCLUSION

Corneal thickness may be a confounding factor in the measurement of intraocular pressure, and this may modify the risk for progression to glaucoma in patients with ocular hypertension.

Probability of Nd:YAG laser capsulotomy after cataract surgery in Olmsted County, Minnesota

PURPOSE

To estimate the cumulative probability of Nd:YAG laser posterior capsulotomy after cataract extraction in a geographically defined population.

METHODS

Rochester Epidemiology Project databases were used to identify retrospectively all Nd:YAG laser posterior capsulotomies performed on Olmsted County, Minnesota, residents who had previously undergone cataract extraction between 1988 and 1996, inclusive. Demographic data and potential risk factors for laser, including age, sex, surgical technique, year of surgery, and intraocular lens material, were obtained by chart review or by retrieval from computer databases. The cumulative probability of Nd:YAG laser posterior capsulotomy was calculated by Kaplan-Meier estimates, and risk factors were analyzed using the Cox proportional hazards model.

RESULTS

A total of 925 Nd:YAG laser posterior capsulotomies were identified after 3541 cataract extractions in 2718 patients. The cumulative probability of Nd:YAG laser posterior capsulotomy after cataract surgery was 6% (95% confidence interval = 5% to 7%) at 1 year, increasing to 38% (35% to 40%) at 9 years. Young age at the time of surgery (P =.02), polymethylmethacrylate intraocular lens material (P <.001), earlier year of surgery (P <.001), and extracapsular extraction (in comparison with phacoemulsification, P <.001) were found to increase significantly the risk of subsequent Nd:YAG laser posterior capsulotomy. Women tended to have a greater probability of Nd:YAG laser posterior capsulotomy (P =.17), but this difference was not statistically significant.

CONCLUSIONS

Nd:YAG laser posterior capsulotomy was common after cataract surgery but infrequent during the first postoperative year. Prolonged follow-up is necessary in investigations of the effects of new cataract surgery technologies on the probability of capsulotomy.

Specificity of the stress electrocardiogram during adenosine myocardial perfusion imaging in patients taking digoxin

BACKGROUND

In patients taking digoxin, the exercise electrocardiogram has a lower specificity for detecting coronary artery disease. However, the effect of digoxin on adenosine-induced ST-segment depression is unknown. The purpose of this study was to evaluate the specificity of the electrocardiogram during adenosine myocardial perfusion imaging in patients taking digoxin.

METHODS

Between May 1991 and September 1997, patients (n = 99) taking digoxin who underwent adenosine stress imaging with thallium-201 or technetium-99m sestamibi and coronary angiography within 3 months were retrospectively identified. Exclusion criteria included prior myocardial infarction, coronary artery angioplasty or bypass surgery, left bundle branch block, paced ventricular rhythm, or significant valvular disease. Twelve-lead electrocardiograms were visually interpreted at baseline, during adenosine infusion, and during the recovery period. The stress electrocardiogram was considered positive if there was > or =1 mm additional horizontal or downsloping ST-segment depression or elevation 0.08 seconds after the J-point compared with the baseline tracing.

RESULTS

ST-segment depression and/or elevation occurred in 24 of 99 patients. There were only 2 false-positive stress electrocardiograms, yielding a specificity of 87% and positive predictive value of 92%. All 8 patients with > or =2 mm ST segment depression had multivessel disease by coronary angiography.

CONCLUSIONS

ST-segment depression or elevation during adenosine myocardial perfusion imaging in patients taking digoxin is highly specific for coronary artery disease. Marked (> or =2 mm) ST-segment depression and/or ST-segment elevation is associated with a high likelihood of multivessel disease.

In vitro comparison of Chen medium and Optisol-GS medium for human corneal storage

PURPOSE

To compare paired human corneas after storage at 4 degrees C in Chen medium (CM) and Optisol-GS medium (OM) for 7, 10, 14, and 21 days.

METHODS

One cornea of each pair from nine human donors was randomly stored in either CM or OM, with its mate cornea stored in the other medium. Three pairs of corneas were stored for 7 days and two pairs each were stored for 10, 14, and 21 days at 4 degrees C. Baseline corneal thickness measurements and endothelial photographs were obtained with a specular microscope. Corneal thickness measurements were also taken on days 7, 10, 14, and 21 of storage. At the end of storage, the corneas were warmed 2 hours before endothelial photographs were taken and were then placed in fixative. A corneal endothelial analysis system was used to compare changes in endothelial size and shape after storage. After fixation, the corneal endothelium was examined by scanning electron microscopy (SEM), and TdT-dUTP terminal nick-end labeling (TUNEL) assays with 4'6-diamidino-2-phenylindole (DAPI) counterstaining were performed on tissue sections of each cornea. A laser scanning confocal microscope and an automated digital analysis system were used to detect the presence of TUNEL-positive apoptotic cells in each cell layer and to determine keratocyte densities.

RESULTS

Mean corneal thickness at 0, 7, 10, 14, 21 days of storage was 0.69 +/- 0.05 mm, 0.69 +/- 0.06 mm, 0.73 +/- 0.08 mm, 0.87 +/- 0.04 mm, and 0.87 +/- 0.03 mm, respectively, for CM and 0.65 +/- 0.06 mm, 0.59 +/- 0.07 mm, 0.63 +/- 0.03 mm, 0.60 +/- 0.03 mm, and 0.69 +/- 0.02 mm, respectively, for OM (p < 0.0001). The mean decrease in endothelial cell density at the end of the 7-, 10-, and 14-day storage periods was 11 +/- 10% for the CM corneas and 5 +/- 5% for the OM corneas (p = 0.18). SEM showed an intact endothelial monolayer in all corneas. The mean percentages of TUNEL-positive cells in epithelium, stroma, and endothelium of CM-stored corneas were 4 +/- 4%, 2 +/- 3%, and 0.1 +/- 0.3%, respectively, and did not differ from the OM-stored corneal values of 4 +/- 3%, 2 +/- 4%, and 0.9 +/- 1.5%. The percentage of TUNEL-positive cells did not increase with storage time. Keratocyte density was 368 +/- 130 cells/mm2 for CM-stored corneas and 447 +/- 96 cells/mm2 for OM-stored corneas (p = 0.13).

CONCLUSIONS

Corneas stored in CM were thicker during storage than those stored in OM. The two storage media did not differ with respect to endothelial cell loss during storage or to the percentage of TUNEL-positive cells or keratocyte density at the end of the storage period.

Infarct size determination by technetium 99m sestamibi single-photon emission computed tomography predicts survival in patients with chronic coronary artery disease

BACKGROUND

The prognostic value of infarct size quantification by technetium 99m sestamibi single-photon emission computed tomography (SPECT) in patients with chronic coronary artery disease (CAD) has not been established. Methods And Results Between September 1994 and May 1995, 1323 patients with known or suspected CAD were referred for perfusion imaging for clinical reasons and had infarct size determined by quantitative SPECT imaging. Patients underwent exercise stress (61%), pharmacologic stress (37%), and rest imaging (3%). Patients were excluded if they had cardiomyopathy, valvular heart disease, or myocardial infarction within 3 weeks of the SPECT study. There were 1224 patients who formed the study group. Follow-up was 94% complete at a median of 1.9 +/- 0.4 years. Sixty-five percent of patients had no measurable infarct. Among the patients with measurable infarcts, the mean infarct size by sestamibi imaging was 15.0% +/- 14.5% of the left ventricle (25% of infarcts </=5% of the left ventricle and 25% of infarcts >/=19% of the left ventricle). By using stepwise regression analysis, age, diabetes, and hypercholesterolemia were all clinical predictors of overall death (P <.05). For cardiac death, only age and diabetes were significant. After adjusting for these clinical variables, infarct size remained an independent predictor of overall death (P =. 001) and survival free of cardiac death (P =.0002). However, when first-pass left ventricular ejection fraction was added to the models, infarct size was no longer significant.

CONCLUSIONS

Infarct size determination by SPECT (99m)Tc sestamibi can predict subsequent death in patients with chronic CAD, although ejection fraction appears to have greater prognostic value.

Distinct hemodynamic profiles in patients with vasovagal syncope: a heterogeneous population

OBJECTIVE

The objective was to investigate mechanisms of vasovagal syncope by identifying laboratory techniques that characterize cardiovascular profiles in patients with vasovagal syncope.

BACKGROUND

The triggering mechanisms of vasovagal syncope are complex. The patient population is likely heterogeneous. We hypothesized that distinct hemodynamic profiles are definable with provocative maneuvers.

METHODS

Three groups of subjects were matched for age and gender: 16 patients with a history of syncope and an inducible vasovagal response during passive tilt table testing (70 degrees, 45 min, group I), 16 with a history of syncope, negative passive tilt table testing but positive isoproterenol tilt table testing (0.05 microg/kg per min, 70 degrees, 10 min, group II), and 16 control subjects. Beat-to-beat hemodynamic functions were determined noninvasively by photo-plethysmography and impedance cardiography.

RESULTS

At baseline, hemodynamic functions were not different among the three groups (supine). In response to tilt before any symptoms developed, total peripheral resistance decreased 9% +/- 14% in group I from baseline supine to tilt position but increased 27% +/- 18% in group II and 28% +/- 17% in controls (p < 0.001). Responses to isoproterenol were not significantly different between group II and controls in supine position. In response to tilt during isoproterenol infusion before any symptoms developed, total peripheral resistance decreased 24% +/- 20% in group II and increased 20% +/- 48% in controls (p = 0.002).

CONCLUSIONS

Group I patients may have impaired ability to increase vascular resistance during orthostatic stress. The inability to overcome isoproterenol-induced vasodilatation during tilt is important in triggering a vasovagal response in group II patients. These data suggest that the population with vasovagal response is heterogeneous. Distinct hemodynamic profiles in response to various provocative maneuvers are definable with noninvasive, continuous monitoring techniques.

Severe aortic stenosis with low transvalvular gradient and severe left ventricular dysfunction:result of aortic valve replacement in 52 patients

BACKGROUND

The outcome of aortic valve replacement in patients with severe aortic stenosis, low transvalvular gradient, and severe left ventricular dysfunction is not well known.

METHODS AND RESULTS

Between 1985 and 1995, 52 patients with left ventricular ejection fraction (EF) < or =35% and aortic stenosis with transvalvular mean gradient <30 mm Hg underwent aortic valve replacement. The mean (+/-SD) preoperative characteristics included EF, 26+/-8%; aortic valve mean gradient, 23+/-4 mm Hg; aortic valve area, 0.7+/-0.2 cm(2); and cardiac output, 3.7+/-1.2 L/min. Simultaneous coronary artery bypass graft surgery was performed in 32 patients (62%). Perioperative (30-day) mortality was 21% (11 of 52 patients). Ten additional patients died during follow-up. Advanced age (P=0.048) and small aortic prosthesis size (P=0.03) were significant predictors of hospital mortality by univariate analysis. By multivariate analysis, the only predictor of surgical mortality was smaller prosthesis size. The only predictor of postoperative survival was improvement in postoperative functional class (P=0.04). Postoperative functional improvement occurred in most patients. Postoperative EF was assessed in 93% of survivors; 74% demonstrated improvement. Positive change in EF was related to smaller preoperative aortic valve area and female sex.

CONCLUSIONS

Despite severe left ventricular dysfunction, low transvalvular mean gradient, and increased operative mortality, aortic valve replacement was associated with improved functional status. Postoperative survival was related to younger patient age and larger aortic prosthesis size, and medium-term survival was related to improved postoperative functional class.

Identification of severe coronary artery disease in patients with a single abnormal coronary territory on exercise thallium-201 imaging: the importance of clinical and exercise variables

OBJECTIVES

The aim of this study was to determine which clinical, exercise and thallium variables can aid in the identification of three-vessel or left main coronary artery disease (3VLMD) in patients with one abnormal coronary territory (either a reversible or fixed defect) on exercise thallium testing and to test the prognostic value of these variables.

BACKGROUND

Although the sensitivity of detection of coronary artery disease by thallium-201 imaging is high, the actual detection of 3VLMD by thallium tomographic images alone is not optimal.

METHODS

A multivariate model for prediction of 3VLMD was developed from several clinical, exercise and thallium-201 variables in a training population of 264 patients who had one abnormal coronary artery territory on exercise thallium testing and had undergone coronary angiography. Using this model, patients were stratified into risk groups for prediction of 3VLMD. A separate validation cohort of 474 consecutive patients who were treated initially with medical therapy and who had one abnormal coronary territory were divided into identical risk groupings by the variables derived from the training population, and they were followed for a median of 7.0 years to evaluate the prognostic value of this model.

RESULTS

The prevalence of 3VLMD was 26% in the training population despite one abnormal thallium coronary territory. Four clinical and exercise variables--diabetes, hypertension, magnitude of ST segment depression, and exercise rate-pressure product-were found to be independent predictors of 3VLMD. In the training population, the prevalence of 3VLMD in low-, intermediate- and high-risk groups was 15%, 22% and 51%, respectively. When the multivariate model was applied to the validation population, the eight-year overall survival rates in the low-, intermediate- and high-risk groups were 89%, 73% and 75%, respectively (p < 0.001).

CONCLUSIONS

A substantial proportion of patients with one abnormal thallium coronary territory have 3VLMD with subsequent divergent outcomes based upon risk stratification by clinical and exercise variables. Consequently, the finding of only a single abnormal coronary territory by thallium-201 perfusion imaging does not necessarily confer a benign prognosis in the absence of consideration of nonimaging variables.

The effect of contact lens wear on the central and peripheral corneal endothelium

PURPOSE

To compare central and peripheral corneal endothelial cell morphometry in normal subjects and long-term contact lens wearers.

METHODS

Endothelial cell density (ECD), coefficient of variation of cell area (CV), and percentage of six-sided cells were measured by contact specular microscopy in the corneal center and temporal periphery of both eyes of 43 long-term contact lens wearers and in 84 normal subjects who had never worn contact lenses. The latter group included 43 age- and sex-matched controls for the contact lens wearers. ECDs were corrected for magnification changes due to corneal thickness.

RESULTS

Central ECD (2,723+/-366 cells/mm2, mean +/- SD) was significantly higher than peripheral ECD (2,646+/-394 cells/mm2) for the normal group (p = 0.01) but not for the contact lens wear group (2,855+/-428 cells/mm2 central, 2,844+/-494 cells/mm2 peripheral, p = 0.84). Peripheral CV was significantly higher than central for normal subjects and contact lens wearers and was significantly higher in both center and periphery in contact lens wearers than in controls. Central percentage of six-sided cells was significantly higher than peripheral for normal subjects and contact lens wearers and was lower in both center and periphery in contact lens wearers than in controls.

CONCLUSIONS

Central ECD was significantly higher by 3% than peripheral ECD in normal subjects, but not in contact lens wearers. The results suggest that contact lens wear causes a mild redistribution of endothelial cells from the central to the peripheral cornea. A reversal of this redistribution after contact lens wear is discontinued for refractive surgery could mask mild central endothelial damage from the refractive procedure.

Is rest or exercise hypertension a cause of a false-positive exercise test?

STUDY OBJECTIVES

To determine if a history of hypertension or an exaggerated rise in exercise systolic BP is associated with a false-positive exercise ECG.

DESIGN, SETTING, AND PATIENTS

Retrospective analysis of the associations between exercise-induced ST-segment depression and a history of hypertension, exercise systolic BP, and several other clinical and exercise test variables. Among 20,097 patients referred for exercise tomographic thallium imaging in a nuclear cardiology laboratory at a tertiary care center, 1,873 patients met inclusion criteria for this study, which included no history of myocardial infarction or coronary artery revascularization, a normal resting ECG, and normal exercise thallium images.

RESULTS

False-positive ST-segment depression occurred in 20% of the population. A history of hypertension was actually associated with a lower likelihood of ST-segment depression (odds ratio, 0.70; 95% confidence interval [CI], 0.55 to 0.89; p = 0. 004). A higher peak exercise systolic BP was associated with a higher likelihood of ST-segment depression (odds ratio, 1.08 for each 10-mm Hg increase in systolic BP; 95% CI, 1.03 to 1.14; p < 0. 001). However, the association between peak exercise systolic BP and ST-segment depression was so weak that this measurement could not be predictive in the individual patient (R(2) = 0.2%). For every 20-mm Hg increase in peak exercise systolic BP, the percentage of patients with ST-segment depression increased by only 3%.

CONCLUSIONS

In patients with normal resting ECGs, we conclude the following: (1) a history of hypertension is not a cause of a false-positive exercise test, and (2) higher exercise systolic BP is a significant but weak predictor of ST-segment depression.

Threshold values for preserved viability with a noninvasive measurement of collateral blood flow during acute myocardial infarction treated by direct coronary angioplasty

BACKGROUND

Quantitative measures of myocardial perfusion defect severity from acute (99m)Tc-sestamibi tomographic images (nadir) have correlated closely with collateral and residual antegrade blood flow during acute myocardial infarction. The purpose of this study was to determine whether a viability threshold could be identified from this measure in patients with acute myocardial infarction treated in a homogeneous manner with successful reperfusion therapy.

METHOD AND RESULTS

The study group consisted of 61 patients with acute myocardial infarction with a risk area of >6% LV treated with primary angioplasty between 120 and 240 minutes after symptom onset. All patients were injected with 20 to 30 mCi of (99m)Tc-sestamibi before primary angioplasty and imaged after the procedure. Acute myocardium at risk (MAR) and subsequent infarct size (IS) were quantified by a threshold program. Severity (nadir) from the acute image was the lowest ratio of minimal/maximum counts from 5 short-axis slices. Infarct location was anterior in 22 and inferior in 39 patients. MAR was 33+/-15% LV and IS was 13+/-15% LV: 23 patients had no infarction despite MAR similar to those with infarction. Receiver-operator characteristic curve analysis identified a nadir value of 0.26 as providing the best separation of patients with and without infarction (sensitivity, 74%; specificity, 74%). This nadir threshold varied by infarct location: anterior defect, 0.21; inferior defect, 0.31. The sensitivity and specificity for absent infarction for these values were anterior, 69% and 67%, and inferior, 88% and 84%, respectively.

CONCLUSIONS

In a time frame in which the presence of residual blood flow is important, the severity of the acute (99m)Tc-sestamibi defect can be used to predict whether infarction will develop despite successful reperfusion.

Long-term prognostic value of Duke treadmill score and exercise thallium-201 imaging performed one to three years after percutaneous transluminal coronary angioplasty

The value of exercise nuclear perfusion imaging performed beyond the 6-month restenosis window for percutaneous transluminal coronary angioplasty (PTCA) has not been explored. This study evaluates the long-term prognostic value of exercise thallium (Tl)-201 imaging after PTCA. We studied the late outcome of a series of 211 patients with tomographic Tl-201 exercise studies performed between 1 to 3 years after PTCA. Follow-up was 96% complete at a median duration of 7.3 years. Most (73%) had 1- or 2-vessel coronary artery disease and normal left ventricular function and 193 (91%) had successful PTCA. Two thirds of the patients were symptomatic at the time of testing. The mean Duke score was 5+/-6 and 125 (60%) patients had a low-risk Duke score. Mean summed stress score was 50+/-9 and mean summed reversibility score was 3+/-4. The 5-year overall survival was 95%, yielding a low annual mortality rate of 1%/year. The summed stress score exhibited a significant association (p = 0.047) with the end point of cardiac death or myocardial infarction. The Duke score was predictive of the combination end point of hard and soft cardiac events (p = 0.002). This study demonstrates that exercise Tl-201 perfusion imaging performed 1 to 3 years after PTCA was predictive of cardiac events.

Long-term outcome of patients with intermediate-risk exercise electrocardiograms who do not have myocardial perfusion defects on radionuclide imaging

BACKGROUND

The appropriate management of patients with intermediate-risk Duke treadmill scores is not established. The purpose of this study was to determine the long-term risk of subsequent cardiovascular events in patients with an intermediate-risk treadmill score who do not have myocardial perfusion defects on radionuclide imaging.

METHODS AND RESULTS

The existing databases of the nuclear cardiology laboratories of 4 academic institutions were searched retrospectively. A total of 4649 patients were identified who had intermediate-risk Duke treadmill scores (-10 to 4), normal or near-normal exercise single photon-emission computed tomographic myocardial perfusion images using either thallium-201 or technetium-99m sestamibi, and no previous coronary revascularization. Follow-up was 95% complete. Cardiovascular survival was 99.8% at 1 year, 99.0% at 5 years, and 98.5% at 7 years. Cardiac survival free of myocardial infarction was similarly high at 96.6% at 7 years. Cardiac survival free of myocardial infarction or revascularization was 87.1% at 7 years. Near-normal scans and cardiac enlargement were independent predictors of time to cardiac death. Seven-year cardiac survival was still high at 97.0% in the 357 patients with near-normal scans and normal cardiac size and somewhat lower, at 89.0%, in the 167 patients with cardiac enlargement.

CONCLUSIONS

Patients with an intermediate-risk treadmill score but with normal or near-normal exercise myocardial perfusion images and normal cardiac sizes are at low risk for subsequent cardiac death and can be safely managed medically until their symptoms warrant revascularization. The appropriate management of patients with cardiac enlargement will remain a matter of clinical judgment.

Comparison of acute myocardial infarct size to two-year mortality in patients <65 to those > or =65 years of age

Older patients have higher in-hospital and longer term mortality after myocardial infarction. To determine if larger infarct size correlates with this observation, myocardium at risk was measured on arrival to the hospital in 347 patients with acute myocardial infarction, and final infarct size was measured at hospital discharge in a subset of 274 of these patients. Myocardium at risk and final infarct size were quantified by tomographic technetium-99m sestamibi imaging. Statistical analyses examined the associations between age, myocardium at risk, final infarct size, and both in-hospital and postdischarge mortality. Median value for age was 64 years, and myocardium at risk was 24% and final infarct size was 12% of the left ventricle. There was no correlation between age and myocardium at risk (r = 0.04, p = NS) or final infarct size (r = 0.06, p = NS). In-hospital mortality was 4% overall and was 2% for patients <65 years old versus 6% for those > or =65 years old (chi-square 11.3, p<0.001). In-hospital mortality was not associated with myocardium at risk (chi square <1, p = NS). For the subset of 274 patients in whom final infarct size was measured, the subsequent 2-year mortality rate was 3% and was independently associated with both age (chi-square 15.6, p<0.001) and final infarct size (chi-square 9.7, p = 0.002). Survival was excellent for patients who were either <65 years old (2-year mortality 1%) or had an infarct size <12% (2-year mortality 0%). For patients > or =65 years old with infarct size > or =12%, 2-year mortality was 13%. These results demonstrate that older patients do not have larger infarcts. Advanced age is associated with higher in-hospital and postdischarge mortality, independent of infarct size.

Cell death during corneal storage at 4 degrees C

PURPOSE

To evaluate cell death in human donor corneas stored at 4 degrees C, to determine whether terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick-end labeling (TUNEL) discriminates between apoptosis and necrosis in corneas stored at 4 degrees C.

METHODS

Ten human corneas were stored in Optisol (Chiron Ophthalmics, Irvine, CA) at 4 degrees C for periods ranging from 0 to 21 days and then fixed for histologic examination. Central corneal sections from each cornea were examined by transmission electron microscopy (TEM) and by the TUNEL assay. Electron micrographs of at least 15 keratocytes each from the anterior, middle, and posterior stroma were examined by three masked observers who graded each cell as normal, apoptotic, or necrotic. Central sections from the same corneas were processed by the TUNEL assay and evaluated with a laser scanning confocal microscope to determine the percentage of apoptotic cells.

RESULTS

By TEM, apoptosis occurred in 23% of the keratocytes and necrosis in 12%. By TUNEL assay, apoptosis occurred in 11% of the keratocytes, with the results in individual corneas being similar to the findings by TEM for apoptosis, rather than for necrosis. By TUNEL assay, apoptosis occurred in 13% of the epithelial cells and in 8% of the endothelial cells. The percentage of apoptotic cells and storage time correlated significantly for the epithelium, but not for the keratocytes or endothelium in this small sample.

CONCLUSIONS

Both apoptosis and necrosis occur in cells during corneal storage at 4 degrees C, with apoptosis appearing to predominate. The TUNEL assay identifies cells undergoing apoptosis, but not necrosis, in corneal tissue. Inhibition of apoptosis in corneas stored at 4 degrees C may prolong acceptable storage times.

Initial endothelial cell density and chronic endothelial cell loss rate in corneal transplants with late endothelial failure

OBJECTIVE

To determine when corneal transplants develop the decreased endothelial cell density that predisposes to late endothelial failure (LEF).

DESIGN

Noted cohort study within a prospective case series.

PARTICIPANTS

The authors compared 21 grafts that developed LEF with the remaining transplants (controls) in a longitudinal cohort study of 500 consecutive penetrating keratoplasties by 1 surgeon. Eyes regrafted during the study, fellow eyes of bilateral cases, and patients who did not want their data used for research purposes were excluded, leaving 389 grafts in 389 patients for analysis.

INTERVENTION

Penetrating keratoplasty.

MAIN OUTCOME MEASURES

Endothelial cell density before surgery and at 2 months and 1, 3, 5, and 10 years after surgery.

RESULTS

Grafts with LEF had lower median endothelial cell densities than other grafts, both before surgery (2710 cells/mm2 vs. 2991 cells/mm2; P = 0.02) and 2 months after surgery (1895 cells/mm2 vs. 2501 cells/mm2; P < 0.001), a difference that was maintained through 5 postoperative years. Despite having lower preoperative cell densities, the grafts with LEF had larger median endothelial cell losses 2 months after keratoplasty (31% vs. 16%, P = 0.002). The endothelial cell loss subsequent to the 2-month examination, however, was not increased in the grafts with LEF. Risk factors for developing LEF included a low endothelial cell density before surgery (P = 0.007) and 2 months after surgery (P = 0.002), aphakia or pseudophakia (P = 0.04), older recipient age (P = 0.002) and older donor age (P = 0.03), and occurrence of an endothelial rejection episode (P = 0.03).

CONCLUSIONS

Corneal grafts with LEF, the major cause of graft failure after 5 postoperative years, fail from low initial endothelial cell density rather than an increased rate of chronic postoperative cell loss. Improved techniques of corneal preservation should decrease the rate of LEF. In addition to low preoperative and 2-month postoperative endothelial cell density, a higher risk of LEF is also seen in patients with aphakia or pseudophakia, older recipient age, older donor age, and occurrence of an endothelial rejection episode.

Prognostic value of a treadmill exercise score in symptomatic patients with nonspecific ST-T abnormalities on resting ECG

CONTEXT

Exercise testing of patients with ST-T abnormalities on the resting electrocardiogram (ECG) is problematic because in the presence of pre-existing ST-T abnormalities, the exercise test is less specific for the diagnosis of coronary artery disease. The prognostic capability of the Duke treadmill score in patients with ST-T abnormalities vs those with normal findings on resting ECG has, to our knowledge, not been evaluated.

OBJECTIVE

To compare the prognostic accuracy of the Duke treadmill score in patients with nonspecific ST-T abnormalities vs those with normal results on resting ECG.

DESIGN

Inception cohort study with 7 years of follow-up.

SETTING

Nuclear cardiology laboratory of a US referral center.

PATIENTS

All symptomatic patients who underwent exercise thallium testing between 1989 and 1991,939 of whom had nonspecific ST-T abnormalities and 1466 of whom had normal findings on resting ECG. Exclusion criteria included congenital, valvular, or cardiomyopathic heart disease; prior coronary artery revascularization; resting ECG with secondary ST-T abnormalities; or missing data.

MAIN OUTCOME MEASURES

Rates of overall mortality and cardiac death for subjects classified by Duke treadmill score risk group.

RESULTS

For the end point cardiac death, 7-year survival in the study population in the low-, intermediate-, and high-risk groups was 97%, 92%, and 76%, respectively (P<.001). Compared with the control group, the study group had lower 7-year survival (94% vs 98%; P<.001), fewer low-risk patients (426 [45%] vs 811 [55%]; P<.001) with worse 7-year survival (97% vs 99%; P= .008), and more high-risk patients (49 [5%] vs 34 [2%];P<.001) with a nonsignificant trend toward worse 7-year survival (76% vs 93%; P= .36).

CONCLUSIONS

The Duke treadmill score can effectively risk-stratify patients with ST-T abnormalities on the resting ECG. In classified risk categories, patients with ST-T abnormalities have a worse prognosis than those with normal results on resting ECG.

Probability of filtration surgery in patients with open-angle glaucoma

OBJECTIVE

To investigate the probability of undergoing filtration surgery in either 1 or both eyes in patients in whom open-angle glaucoma was newly diagnosed.

METHODS AND DESIGN

A retrospective community-based study of 295 residents of Olmsted County, Minnesota, in whom open-angle glaucoma was newly diagnosed between January 1, 1965, and December 31, 1980, was performed. Kaplan-Meier methods were used to estimate the cumulative probability of undergoing filtration surgery during a 20-year period.

RESULTS

At 20 years of follow-up, the Kaplan-Meier cumulative probability of undergoing filtration surgery in at least 1 eye was estimated to be 23% (95% confidence interval, 16%-30%), and in both eyes the estimate was 12% (95% confidence interval, 6%-17%). Patients with optic nerve damage at the time of diagnosis were more likely to undergo surgery than patients with elevated intraocular pressure but no damage (1 eye, 39% vs 15%; both eyes, 27% vs 5%).

CONCLUSION

This retrospective study of a white population newly diagnosed as having and treated for open-angle glaucoma indicates that while most patients did not undergo filtration surgery in the course of glaucoma therapy, at least one third of those with glaucomatous damage at the time of diagnosis underwent filtration surgery.

Comparison of three methods for human corneal cryopreservation that utilize dimethyl sulfoxide

We compared endothelial cell survival in human corneas after cryopreservation by three methods that utilize dimethyl sulfoxide. Twenty-eight human cadaver corneas were cryopreserved by one of three methods, stored briefly over liquid nitrogen, thawed, cultured at 37 degrees C for 3 days, and fixed for scanning electron microscopy. Seventeen control corneas underwent identical cryoprotectant immersion and culture protocols but were not frozen. Endothelial photographs taken after 1 and 3 days of culture were analyzed. Endothelial cell losses in cryopreserved corneas by Methods 1, 2, and 3, respectively, were 36, 22, and 10% after 1 day of culture and 57, 36, and 27% after 3 days of culture. Cryopreservation by Method 3 had less cell loss than Methods 1 or 2 (P<0.02) but greater cell loss than the control corneas for Method 3 (P<0.001). No loss of cells occurred in the control corneas for Methods 1 and 3 but substantial cell loss (26%) occurred in the control corneas for Method 2. Polymegethism and pleomorphism of the endothelial cells were seen in the corneas that lost cells. The endothelial cell loss of 10% seen after 1 day of culture in human corneas cryopreserved by Method 3 is similar to the loss that occurs during organ culture storage as currently used clinically and therefore would be acceptable for clinical use. After 3 days of culture, however, the cell loss had increased significantly to 27%. This additional decrease in cell number that occurs in culture may represent latent cryodamage and must be understood and overcome in vivo before the technique can be used clinically.

Comparison of recording systems and analysis methods in specular microscopy

PURPOSE

To compare corneal endothelial cell images from contact and automated noncontact specular microscopes and to compare endothelial image analysis by the Konan Robo Center Method and the Bio Optics Bambi Corners Method.

METHODS

Twenty-six normal corneas of 13 subjects and 41 penetrating keratoplasties (PKs) of 38 patients were photographed with a Keeler-Konan contact specular microscope and a Konan Noncon Robo automated noncontact specular microscope. (i) After measuring and calibrating the magnification of each instrument, we digitized the cellular apices and analyzed the images from both instruments by using the Corners Method modified to accept x and y calibrations. (ii) Using the internal calibration marks of the Konan Noncon Robo specular microscope for calibration of magnification (as required for the Center Method), we evaluated identical cells on images from this microscope by both the Center Method and the Corners Method. (iii) We evaluated the reproducibility of both methods by repeating measurements on the same image.

RESULTS

(i) When the images were properly calibrated for magnification by using an external scale, endothelial cell density (ECD) of normal corneas was 2,703 +/- 354 (mean +/- SD) cells/mm2 by contact and 2,685 +/- 357 cells/mm2 by noncontact techniques (p = 0.51). ECD of PK corneas was 1,767 +/- 773 cells/mm2 by contact and 1,807 +/- 775 cells/mm2 by noncontact techniques (p = 0.31). (ii) When images from the Konan Noncon Robo specular microscope were calibrated for magnification on the internal marks, the measured ECD from the same noncontact photographs was 6% less (p < 0.001). ECD was then 2,519 +/- 294 cells/mm2 (means +/- SD) by the Center Method and 2,523 +/- 305 cells/mm2 by the Corners Method (p = 0.55) in normal corneas and 1,715 +/- 748 cells/mm2 by the Center Method and 1,731 +/- 763 cells/mm2 by the Corners Method (p = 0.04) in PK corneas. (iii) The coefficient of variation of repeated measurements on the same normal image was 0.0025 for the Centers Method and 0.0099 for the Corners Method.

CONCLUSIONS

(i) Images from the automated noncontact specular microscope may be used interchangeably with those from the contact specular microscope to measure ECD, but only if both are properly calibrated by measuring an external scale. (ii) As a method of analysis, the Center Method is equivalent to the Corners Method in normal corneas, but the proprietary internal calibration of the Center Method, which is required for its use, yields ECDs approximately 6% less than when an external scale is used for distance calibration. (iii) Cell density measurements by both the Center Method and the Corners Method were reproducible within 1%.

Pulmonary function monitoring during adenosine myocardial perfusion scintigraphy in patients with chronic obstructive pulmonary disease

OBJECTIVE

To determine whether adenosine could be safely administered to patients with chronic obstructive pulmonary disease (COPD) for coronary vasodilatation during perfusion scintigraphy without causing bronchospasm.

MATERIAL AND METHODS

The study was divided into two phases. In the monitoring phase, patients with COPD were pretreated with an inhaled bronchodilator (albuterol) and had pulmonary function monitored during the infusion of a graduated dose of adenosine. Eligibility for entry into this phase of the study was determined on the basis of results of pulmonary function testing (PFT) during resting. Once we had shown that adenosine could be safely administered to patients with COPD, an implementation phase was begun. Entry did not require resting PFT, and patients were administered adenosine without monitoring of pulmonary function. Differences between patients with normal pulmonary function or mild COPD and those with more severe COPD were analyzed statistically.

RESULTS

Of 94 patients entered into the monitoring phase, none had obvious bronchospasm. The dosage of adenosine was reduced in four patients because of a decrease in forced expiratory volume in 1 second (FEV1) of 20% in comparison with baseline (FEV1 before administration of albuterol). The mean FEV1 decreased slightly from 1.83 L after administration of albuterol to 1.78 L during the maximal adenosine dose. Patients with a remote history of asthma, positive result of a methacholine challenge test, or mild COPD (FEV1 60 to 80% of the maximal predicted value for age) did not differ significantly in their response to infusion of adenosine from those with moderate or severe COPD (FEV1 30 to 59% of the maximum predicted for age). Of 117 patients in the implementation phase, 2 had bronchospasm during infusion of adenosine that was quickly terminated by stopping the administration in one patient and reducing the dose of adenosine in the other.

CONCLUSION

This study shows that adenosine can be safely administered intravenously to selected patients with known or suspected COPD to produce coronary vasodilatation for myocardial perfusion imaging. Patients who are within the guidelines established for this study should be considered for adenosine coronary vasodilatation with use of bronchodilator pretreatment, a graduated dose of adenosine, and regular chest auscultation during the infusion.

Sensitivity to orthostatic stress and beta-receptor activation in patients with isoproterenol-induced vasovagal syncope: a case controlled study

Cardiomotor and vasomotor responses were assessed during isoproterenol tilt-induced vasovagal reaction in patients with a history of syncope. In a case controlled study, all patients and controls were subjected to a standard protocol: baseline supine (10 min), baseline tilt (70 degrees, 45 min), isoproterenol supine (0.05 microgram/kg per min, 10 min), and isoproterenol tilt (70 degrees, 10 min). The participants were 11 consecutive patients referred for syncope evaluation (5 men, 6 women; mean age, 34.1 +/- 10.4 years; range, 18-56 years) and 11 age and sex matched controls (5 men, 6 women; mean age, 35.5 +/- 12.2 years; range, 19-63 years). On-line, beat-to-beat measurements of cardiomotor functions (heart rate, stroke volume, and cardiac output) and vasomotor functions (systolic, mean, and diastolic blood pressures and total peripheral resistance [TPR]) were detected noninvasively by volume clamp photoplethysmography and impedance cardiography. Patients and controls had similar cardiomotor and vasomotor responses during passive tilt and during isoproterenol infusion in the supine position. Immediately after tilt during isoproterenol infusion and before the onset of symptoms, decreases in vasomotor functions were significant in study patients when compared with those in controls; whereas responses in cardiomotor functions were similar between the two groups. When compared with baseline supine findings, TPR decreased by 56.5% +/- 10.9% and 29.5% +/- 23.3% in the patient population and controls, respectively (P = 0.005). When compared with isoproterenol supine findings, TPR decreased by 27.5% +/- 22.8% in the study patients and increased by 22.6% +/- 48.1% in the controls (P = 0.005). The inability to overcome isoproterenol-induced vasodilation during orthostatic stress played an important role in the initiation of a vasovagal response. These observations hold the key to early detection of hemodynamic changes and potential therapeutic interventions before patients become symptomatic.

Pediatric third, fourth, and sixth nerve palsies: a population-based study

PURPOSE

To determine the population-based incidence and cause of cranial nerve palsies affecting ocular motility in children in the circumscribed population of Olmsted County, Minnesota.

METHODS

The Rochester Epidemiology Project medical records linkage system captures virtually all medical care provided to Olmsted County residents. By means of this database, all cases of third, fourth, and sixth cranial nerve palsy were identified among county residents less than 18 years of age from 1978 through 1992. Medical records were reviewed to confirm the diagnosis, determine the cause, and document county residency. Incidence rates were adjusted to the age and sex distribution of the 1990 white population in the United States.

RESULTS

Over this 15-year period, 36 incidence cases of cranial nerve palsy were identified in 35 children in this defined population. The age-adjusted and sex-adjusted annual incidence of third, fourth, and sixth nerve palsies combined was 7.6 per 100,000 (95% confidence interval, 5.1 to 10.1). The most commonly affected nerve was the fourth (36%), followed by the sixth (33%), the third (22%), and multiple nerve palsies (9%). The most common cause was congenital for third and fourth nerve palsy, undetermined for sixth, and trauma for multiple nerve palsies. Although three cases were associated with neoplasia, a cranial nerve palsy was not present at the time of diagnosis in any case.

CONCLUSIONS

Unlike many institutionally based referral series, our population-based study provides data on the incidence and cause of third, fourth, and sixth nerve palsies in a geographically defined population. In contrast to previous institutionally based series, nearly half the cases were congenital in origin, and in no case did intracranial neoplasia present as an isolated nerve palsy.

Relation between mode of pacing and long-term survival in the very elderly

OBJECTIVES

This study analyzes the relationship between pacing mode and long-term survival in a large group of very elderly patients (> or = 80 years old).

BACKGROUND

The relationship between pacing mode and long-term survival is not clear. Because the number of very elderly who are candidates for pacing is increasing, issues related to pacemaker (PM) use in the elderly have important clinical and economic implications.

METHODS

We retrospectively reviewed 432 patients (mean age, 84.5+/-3.9 years) who received their initial PM (ventricular in 310 and dual chamber in 122) between 1980 and 1992. Follow-up was complete (3.5+/-2.6 years). Observed survival was estimated by the Kaplan-Meier method. Age- and gender-matched cohorts from the Minnesota population were used for expected survival. Log-rank test and Cox regression hazard model were used for univariate and multivariate analyses.

RESULTS

Patients with ventricular PMs appeared to have poor overall survival compared with those with dual-chamber PMs. Observed survival after PM implantation in high grade atrioventricular block (AVB) patients was significantly worse than expected survival of the age- and gender-matched population (p < 0.0001), whereas observed survival of patients with sinus node dysfunction was not significantly different from expected survival of the matched population (p = 0.413). By univariate analysis, ventricular pacing in patients with AVB appeared to be associated with poor survival compared with dual-chamber pacing (hazard ratio [HR] 2.08; 95% confidence interval [CI] 1.33 to 3.33). After multivariate analysis, this difference was no longer significant (HR 1.41; 95% CI 0.88 to 2.27). Independent predictors of all-cause mortality were number of comorbid illnesses, New York Heart Association functional class, left ventricular depression and older age at implant. Pacing mode was not an independent predictor of overall survival. Older age at implantation, diabetes mellitus, dementia, history of paroxysmal atrial fibrillation and earlier year of implantation were independent predictors of ventricular pacemaker selection.

CONCLUSIONS

After PM implantation, long-term survival among very elderly patients was not affected by pacing mode after correction of baseline differences. Selection bias was present in pacing mode in the very elderly, with ventricular pacing selected for sicker and older patients, perhaps partly explaining the apparent "beneficial impact on survival" observed with dual-chamber pacing.

Utility of a single-stage isoproterenol tilt table test in adults: a randomized comparison with passive head-up tilt

OBJECTIVES

This study was conducted to develop a time-efficient tilt table test.

BACKGROUND

Current protocols of tilt table testing are quite time-consuming. This study was designed to assess the diagnostic value, tolerance and procedural time of a single-stage isoproterenol tilt table protocol.

METHODS

A single-stage isoproterenol tilt table test was compared with the passive tilt table test. The study was prospectively designed in a randomized and crossover fashion.

RESULTS

The study population consisted of 111 patients with a history of syncope (mean age 55 +/- 20 years). Of the total, 62 patients (56%; 95% confidence interval, 46% to 65%) had a positive vasovagal response during isoproterenol tilt table testing and 35 (32%; 23% to 41%) during passive tilt table testing (p = 0.002). The mean procedural times of the study population were 11.7 +/- 3.6 min and 36.9 +/- 13.3 min for isoproterenol and passive tilt table testing, respectively (p < 0.001). All patients tolerated single-stage isoproterenol testing. In the 23 control subjects (mean age 34 +/- 11 years), the apparent specificities were 91% (72% to 99%) and 83% (61% to 99%) for passive and single-stage tilt table testing, respectively.

CONCLUSIONS

The single-stage isoproterenol tilt table test was more effective in inducing a positive vasovagal response in an adult population than the standard passive tilt table test, and it significantly reduced the procedural time. The increase in positive yield was associated with a moderate decrease in apparent specificity. These observations support the conclusion that single-stage tilt table testing could be a reasonable diagnostic option in patients undergoing syncope evaluation.

Estimation of corneal endothelial pump function in long-term contact lens wearers

PURPOSE

To study the effects of long-term contact lens wear on morphologic and physiologic properties of corneal endothelial cells.

METHODS

The endothelial permeability to fluorescein and the rate of corneal deswelling from hypoxia-induced edema were measured in 20 long-term (mean, 17+/-9 years; range, 5-33 years) contact lens wearers and 20 age-matched control subjects. From these data, the relative endothelial pump rate in each subject was estimated, based on the pump-leak hypothesis of corneal hydration control. Corneal autofluorescence and the aqueous humor flow rate were determined by fluorescein fluorophotometry. Images of corneal endothelial cells were recorded by using specular microscopy, and morphologic indices (cell density, coefficient of variation of cell area, percentage of hexagonal cells, and skewness) were determined.

RESULTS

No statistically significant differences were found between the contact lens and control groups in endothelial permeability, corneal deswelling, relative endothelial pump rate ([mean +/- SD] 1.07+/-0.33 relative pump units versus 1.01+/-0.25 relative pump units; contact lens versus control; P = 0.57), and endothelial cell density. Contact lens wearers had a significantly higher aqueous humor flow rate (3.57+/-1.03 microl/min versus 2.77+/-0.51 microl/min; P = 0.005), coefficient of variation of cell area (0.35+/-0.09 versus 0.28+/-0.04; P = 0.006), and corneal autofluorescence (3.1+/-0.6 ng/ml versus 2.3+/-0.3 ng/ml fluorescein equivalents; P < 0.001) than did non-contact lens wearers.

CONCLUSIONS

Despite the known effects of long-term contact lens wear on corneal endothelial morphometry, no effect on endothelial function was found.