Ferrous Iron and Sulfur Oxidation and Ferric Iron Reduction Activities of Thiobacillus ferrooxidans Are Affected by Growth on Ferrous Iron, Sulfur, or a Sulfide Ore

Eight strains of Thiobacillus ferrooxidans (laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of Thiobacillus thiooxidans (laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe), elemental sulfur (S), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe - and S-oxidizing activities (O(2) consumption) and anaerobic S-oxidizing activity with ferric iron (Fe) (Fe formation). Fe-grown T. ferrooxidans cells oxidized S aerobically at a rate of 2 to 4% of the Fe oxidation rate. The rate of anaerobic S oxidation with Fe was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe to that on S produced cells with relatively undiminished Fe oxidation activities and increased S oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe oxidation and anaerobic S oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe-grown strains and on ore 2 of all Fe-grown strains resulted in very high yields of cells with high Fe and S oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the T. ferrooxidans strains studied have the ability to produce cells with Fe and S oxidation and Fe reduction activities, but their levels are influenced by growth substrates and strain differences.

Preoperative NT-proBNP and CRP predict perioperative major cardiovascular events in non-cardiac surgery

OBJECTIVE

To investigate whether simple and non-invasive measurement of N-terminal pro-brain natriuretic peptide (NT-proBNP) and/or C-reactive protein (CRP) can predict perioperative major cardiovascular event (PMCE).

DESIGN

Prospective, single-centre, cohort study.

SETTING

A 1900-bed tertiary-care university hospital in Seoul, Korea Design and

PATIENTS

The predictive power of NT-proBNP, CRP and Revised Cardiac Risk Index (RCRI) for the risk of PMCE (myocardial infarction, pulmonary oedema or cardiovascular death) were evaluated from a prospective cohort of 2054 elective major non-cardiac surgery patients. Optimal cut-off values were derived from receiver operating characteristic curve (ROC) analysis.

MAIN OUTCOME MEASUREMENT

PMCE (myocardial infarction, pulmonary oedema or cardiovascular death) within postoperative 30 days.

RESULTS

PMCE developed in a total of 290 patients (14.1%). Each increasing quartile of NT-proBNP or CRP level was associated with a greater risk of PMCE after adjustment for traditional clinical risk factors. The relative risk (RR) of highest versus lowest quartile was 5.2 for NT-proBNP (p<0.001) and 3.7 for CRP (p<0.001). Both NT-proBNP (cut-off = 301 ng/l) and CRP (cut-off = 3.4 mg/l) predicted PMCE better than RCRI (cut-off = 2) by ROC analysis (p<0.001). Moreover, the predictive power of RCRI (adjusted RR = 1.5) could be improved significantly by addition of CRP and NT-proBNP to RCRI (adjusted RR 4.6) (p<0.001).

CONCLUSIONS

High preoperative NT-proBNP or CRP is a strong and independent predictor of perioperative major cardiovascular event in non-cardiac surgery. The predictive power of current clinical risk evaluation system would be strengthened by these biomarkers.

Arthrodesis of the knee using cannulated screws

We retrospectively evaluated eight patients who underwent arthrodesis of the knee using cannulated screws. There were six women and two men, with a mean age of 53 years. The indications for arthrodesis were failed total knee arthroplasty, septic arthritis, tuberculosis, and recurrent persistent infection. Solid union was achieved in all patients at a mean of 6.1 months. One patient required autogenous bone graft for delayed union. One suffered skin necrosis which was treated with skin grafting. The mean limb-length discrepancy was 3.1 cm. On a visual analogue scale, the mean pain score improved from 7.9 to 3.3. According to the Knee Injury and Osteoarthritis Outcome score quality of life items, the mean score improved from 38.3 pre-operatively to 76.6 at follow-up. Cannulated screws provide a high rate of union in arthrodesis of the knee with minimal complications, patient convenience, and a simple surgical technique.

Combination drug therapy using edaravone and Daio-Orengedoku-to after transient focal ischemia in rats

In this study, we investigated the effect of Daio-Orengedoku-to (DOT) on ischemic brain damage in a rat model of focal ischemia-reperfusion and attempted to identify synergistic effects for the combination of edaravone and DOT against ischemic insult. Ischemia was induced by intraluminal occlusion of the right middle cerebral artery for 2 h and reperfusion followed for 22 h. To determine the neuroprotective effect of DOT, it was administered orally just before reperfusion and then 2 h after reperfusion. To examine the effects of combination therapy on survival, rats were divided into groups treated with edaravone, DOT, and edaravone and DOT. Microglial activation, neutrophil infiltration and brain-derived neurotrophic factor (BDNF) expression were examined in surviving animals. Infarct volume was significantly reduced by DOT (100, 200 and 400 mg/kg; P < 0.05), and edaravone plus DOT markedly improved the survival rate after transient ischemia (P = 0.0133). Microglial activation was reduced by edaravone and DOT and their combination (P < 0.05), and neutrophil infiltration was lowered in these groups (P < 0.05). BDNF-positive cells were increased in the combination edaravone and DOT group (P < 0.05). It appears that the neuroprotective mechanisms of combined therapy involve inhibition of microglial activation, reduction of invading neutrophils and enhancement of BDNF expression.

Left ventricular diastolic functional reserve during exercise in patients with impaired myocardial relaxation at rest

BACKGROUND

Patients with similar grade diastolic dysfunction at rest may have a spectrum of alterations in diastolic function during exercise.

OBJECTIVE

To evaluate (a) whether exercise could unmask further diastolic abnormalities not evident during rest; (b) whether diastolic functional reserve during exercise is associated with exercise capacity.

METHODS

141 subjects (77 male, mean (SD) age 62 (9)) with abnormal left ventricular (LV) relaxation (mitral E/A <0.75) and/or deceleration time >240 ms, underwent graded supine bicycle exercise with simultaneous respiratory gas analysis and two-dimensional and Doppler echocardiographic study. Mitral inflow and annular velocities were measured at rest and during exercise. The LV diastolic function reserve index (DFRI) was calculated.

RESULTS

Patients were classified into two groups: group 1 (n = 64), DFRI <13.5; group 2 (n = 77), DFRI >or=13.5. The ratio of E/E' to stroke volume was used as an index of ventricular elastance (Ed). No significant differences between the groups in mitral inflow and annular velocities at rest were found. Mean (SD) Ed was not significantly different at rest between the groups (0.19 (0.07) vs 0.18 (0.06), p = 0.29). Ed was significantly higher during exercise in group 1 than in group 2 (25 W, 0.21 (0.09) vs 0.14 (0.04), p<0.001; 50 W, 0.22 (0.10) vs 0.15 (0.04), p<0.001). Group 1 subjects had a shorter exercise duration (8.2 (2.7) vs 9.4 (3.7) min, p = 0.04) and lower peak oxygen consumption (17.5 (4.5) vs 20.2 (5.4) ml/kg/min, p = 0.005).

CONCLUSIONS

Despite similar mitral flow and annular velocities at rest, different responses to exercise were seen in patients with abnormal LV relaxation at rest. Lower LV diastolic functional reserve was associated with higher ventricular elastance during exercise, and reduced exercise capacity.

'Hypersynchronisation' by tissue velocity imaging in patients with cardiac amyloidosis

OBJECTIVE

It is unknown if some patients with cardiac amyloidosis (CA) have mechanical dyssynchrony, as has been demonstrated in patients with ischaemic and dilated cardiomyopathies. The aim of this study was to assess mechanical dyssynchrony in patients with CA using tissue velocity imaging (TVI) and to define its usefulness for risk stratification.

DESIGN AND PATIENTS

We included 121 patients with primary amyloidosis and 37 age-matched and sex-matched controls. Patients were divided into two groups: 60 with advanced-CA and 61 with no-advanced-CA, according to left ventricular (LV) wall thickness and diastolic dysfunction. Dyssynchrony assessment included: (1) atrioventricular dyssynchrony (dys), (2) interventricular dys, (3) intraventricular dys assessed longitudinally, using the standard deviation of time to systolic peak velocity (Ts-SD) of the 12 basal and mid level LV segments, and (4) intraventricular dys assessed radially, using the difference in radial Ts between mid anteroseptal and mid posterior segments.

OUTCOME

Primary end-point was all-cause death. During a median follow-up of 13 months there were 35 events among patients.

RESULTS

Contrary to the hypothesis, the intraventricular dys indices in advanced-CA patients were reduced compared to either the no-advanced-CA group or to controls (Ts-SD: 12.1 (9.0); 35.1 (18.6); 24.5 (14.1), respectively, p<0.001). This reduction was primarily the result of decreased ejection time (ET). Moreover, ET was the most significant predictor of survival (HR = 0.98, p<0.001).

CONCLUSIONS

The regional timing of systolic motion measured by TVI was abnormally synchronised in the patients with advanced-CA. ET reduction plays a prominent part in this process and should be considered an essential parameter for assessment of patients with cardiac amyloidosis.

Ethnic characteristics of eyelashes: a comparative analysis in Asian and Caucasian females

BACKGROUND

Despite similar biochemical composition of human hair between races, physico-morphological characteristics are not identical in different ethnic groups. Eyelashes have been investigated far less than scalp hair, and the information available is insufficient.

OBJECTIVES

To obtain basic information about eyelashes and to clarify differences between female eyelashes in Asians and Caucasians.

METHODS

Twenty Asian and 10 white Caucasian female volunteers aged between 20 and 29 years were admitted to the study. Lateral digital photographs of upper eyelashes were taken and curl-up and lift-up angles of upper eyelashes were measured from lateral views. Images of upper eyelashes were also taken using the phototrichogram technique and total numbers, lengths and thicknesses of upper eyelashes were obtained (a total of 4661 eyelashes; 2946 for Asian, 1715 for Caucasian). The central portion of the eyelashes or whole eyelashes were clipped and images were taken immediately and 7 days later to obtain the growth rate and anagen ratio of upper eyelashes. Numbers and thickness of eyelash cuticular layers were obtained by electron microscopy.

RESULTS

Compared with Caucasians, Asian eyelashes revealed lower lift-up and curl-up angles, fewer numbers and a thicker transverse diameter. However, no statistical difference was observed in length or growth rate. Duration of anagen was estimated at about 2 months. The eyelash anagen ratio obtained from five Asians was 17.8 +/- 3.3%. By electron microscopy, the number of cuticular layers in transverse section was greater in Asian (8.0 +/- 1.2) than Caucasian females (6.5 +/- 1.1), but no statistical difference was found in single cuticle layer thickness between the two groups. Moreover, eyelash characteristics were not influenced by eye makeup in either race.

CONCLUSIONS

Our results on eyelash morphology and growth characteristics demonstrated significant ethnic differences in Asian and Caucasian females that could provide basic information for future investigations.

Calibration of CE-QUAL-W2 for a monomictic reservoir in a monsoon climate area

The impact of inflow mixing on reservoir stratification is significant for reservoirs situated in a monsoon climate area. It cause difficulty in the calibration of a two-dimensional hydrodynamic and water quality model, CE-QUAL-W2 that was recently adopted for a real-time turbidity monitoring and modelling system (RTMMS) for a reservoir in Korea. This paper presents a systematic calibration and verification processe of the model for the reservoir. A sensitivity analysis showed that wind sheltering, Chezy, and sediment heat exchange coefficients are most sensitive to stratification structure. Inflow temperature was very sensitive during a year of normal precipitation, but it is not significant during a year of drought. Residual analysis revealed that the model has shortcomings in the simulation of water temperature near the metalimnetic zone without calibration. After calibration, however, the absolute mean errors between observed and simulated values were placed within 0.116-1.190 degrees C. Its performance was maintained under heavy flood events during the verification stage, which implies that the model is ready to use for the simulation of turbidity plume in the RTMMS under various hydrologic conditions. The suggested model calibration strategy and relevant results may be adopted for other reservoirs located in a monsoon climate area.

Personal experiences and algorithm of endoscopically assisted subperiosteal face lift in orientals for 5 years

Orientals are anatomically distinct from Caucasians and are characterized by a thick dermis, a Mongoloid slant of the palpebral fissure, a relatively prominent zygoma and mandible angle, and a relatively flat nose. Given these characteristics, it was believed that the subperiosteal face lift was not suitable for Orientals. However, at our institution, endoscopically assisted subperiosteal face lifts were performed from May of 1994 to October of 1998 on 236 patients; variable pitfalls, as well as satisfying results, were reported. Patient ages ranged from 29 to 66 years (mean age, 55.2 years), and follow-up ranged from 6 to 44 months (mean follow-up, 23 months). All forehead and brow lifts were performed using an endoscopic guide, and routine corrugator resections and procerus myotomies were performed. Three slanted cortical tunnels were made at the corresponding locations on the outer table of the calvarium, and 1-0 nylon or screw suspension and fixation were performed after a 1-cm to 2-cm lift. Midface lifts were performed through lower blepharoplasty incisions and vertical temporal incisions instead of through conventional preauricular and postauricular incisions. Dissections were made subperiosteally and over the deep layers of deep temporal fascia. Malar fat pads were suspended with 1-0 nylon and affixed to deep temporal fascia. Most patients have been satisfied with their postoperative results, but unfavorable results and complications have been reported. Complications were classified as early or late complications or unfavorable results on the basis of the 3-week postoperative evaluation. There were 28 early complications (11.9 percent), consisting of ecchymosis with edema (persisting for up to 4 weeks), paresthesia, lagophthalmos, accentuated Mongoloid slant, small dimpling on the scalp, and scalp fold formation on the fixation site. There were 13 late complications/unfavorable results (5.5 percent), consisting of insufficient lift, exaggeration of sunken upper eyelids, intermittent headaches, itching sensations, and paresthesia on the scalp. The unfavorable results occurred in the patients who had previously undergone blepharoplasty and in those who had a history of foreign body injections into the face, fatty and thick faces, sunken upper eyelids, Mongoloid slants, and asymmetric facial expressions. Through understanding the anatomic characteristics of the Oriental face (i.e., thick dermis, Mongoloid slant of palpebral fissure, prominent zygoma and mandible angle, and flat nose), satisfying results were achieved by appropriate application of the modified procedures.

Annulus paradoxus: transmitral flow velocity to mitral annular velocity ratio is inversely proportional to pulmonary capillary wedge pressure in patients with constrictive pericarditis

BACKGROUND

The early diastolic velocity of the mitral annulus (E') is reduced in patients with diastolic dysfunction and increased filling pressures. Because transmitral inflow early velocity (E) increases progressively with higher filling pressures, E/E' has been shown to have a strong positive relationship with pulmonary capillary wedge pressure (PCWP) and left ventricular end-diastolic pressure. However, previous studies have primarily involved patients without a pericardial abnormality. In constrictive pericarditis (CP), E' is not reduced, despite increased filling pressures. This study evaluated the relationship between E/E' and PCWP in patients with CP.

METHODS AND RESULTS

We studied 10 patients (8 men; mean age, 64+/-7 years) with surgically confirmed CP. Doppler echocardiography was performed to measure early and late diastolic transmitral flow velocities. Tissue Doppler echocardiography was performed to measure E'. PCWP was measured with right heart catheterization. All patients were in sinus rhythm. Mean E and E' were 91+/-15 cm/s and 11+/-4 cm/s, respectively. Mean PCWP was 25+/-6 mm Hg. E' was positively correlated with PCWP (r=0.69, P=0.027). There was a significant inverse correlation between E/E' and PCWP (r=-0.74, P=0.014). Despite high left ventricular filling pressures, E/E' (mean, 9+/-4) was <15 in all but 1 patient.

CONCLUSIONS

Paradoxical to the positive correlation between E/E' and PCWP in patients with myocardial disease, an inverse relationship was found in patients with CP.

Contrast dobutamine stress echocardiography: clinical practice assessment in 300 consecutive patients

In this study we compared non-contrast imaging with contrast imaging of the left ventricle during dobutamine stress echocardiography (DSE). Wall segment visualization, image quality, and confidence of interpretation were determined with and without the use of intravenous Optison, a second-generation echocardiographic contrast agent, in 300 consecutive patients undergoing rest and peak DSE. At rest and at peak stress, the percentage of wall segments visualized, image quality, and confidence of interpretation were better with contrast compared with non-contrast imaging. No significant decrease was seen in wall segment visualization, image quality, or confidence of interpretation from rest to peak stress in images obtained with contrast, unlike the images obtained without contrast from rest to peak stress. The use of the intravenous echocardiographic contrast agent Optison during DSE significantly improved wall segment visualization and image quality at rest and at peak stress, resulting in improved confidence of interpretation.

Prognostic value of exercise echocardiography in patients after coronary artery bypass surgery

To assess the prognostic value of exercise echocardiography in patients with prior coronary artery bypass surgery, follow-up was obtained in 718 patients (591 men [82%] and 127 women [18%], aged 67 +/- 9 years) who underwent clinically indicated exercise echocardiography 5.7 +/- 4.7 years after coronary bypass surgery. Resting wall motion abnormalities were present in 479 patients (67%). New or worsening wall motion abnormalities developed with exercise in 366 patients (51%). During a median follow-up of 2.9 years, cardiac events included cardiac death in 36 patients and nonfatal myocardial infarction in 40 patients. The addition of the exercise echocardiographic variables, abnormal left ventricular end-systolic volume response and exercise ejection fraction to the clinical, resting echocardiographic and exercise electrocardiographic model provided incremental information in predicting cardiac events (chi-square 37 to chi-square 42, p = 0.02) and cardiac death (chi-square 38 to chi-square 43, p <0.02). Exercise echocardiography provides prognostic information in patients after coronary artery bypass surgery, incremental to clinical, rest echocardiographic, and exercise electrocardiographic variables.

Mechanism of oxidation of inorganic sulfur compounds by thiosulfate-grown Thiobacillus thiooxidans

Thiobacillus thiooxidans was grown at pH 5 on thiosulfate as an energy source, and the mechanism of oxidation of inorganic sulfur compounds was studied by the effect of inhibitors, stoichiometries of oxygen consumption and sulfur, sulfite, or tetrathionate accumulation, and cytochrome reduction by substrates. Both intact cells and cell-free extracts were used in the study. The results are consistent with the pathway with sulfur and sulfite as the key intermediates. Thiosulfate was oxidized after cleavage to sulfur and sulfite as intermediates at pH 5, the optimal growth pH on thiosulfate, but after initial condensation to tetrathionate at pH 2.3 where the organism failed to grow. N-Ethylmaleimide (NEM) inhibited sulfur oxidation directly and the oxidation of thiosulfate or tetrathionate indirectly. It did not inhibit the sulfite oxidation by cells, but inhibited any reduction of cell cytochromes by sulfur, thiosulfate, tetrathionate, and sulfite. NEM probably binds sulfhydryl groups, which are possibly essential in supplying electrons to initiate sulfur oxidation. 2-Heptyl-4-hydroxy-quinoline N-oxide (HQNO) inhibited the oxidation of sulfite directly and that of sulfur, thiosulfate, and tetrathionate indirectly. Uncouplers, carbonyl cyanide-m-chlorophenylhydrazone (CCCP) and 2,4-dinitrophenol (DNP), inhibited sulfite oxidation by cells, but not the oxidation by extracts, while HQNO inhibited both. It is proposed that HQNO inhibits the oxidation of sulfite at the cytochrome b site both in cells and extracts, but uncouplers inhibit the oxidation in cells only by collapsing the energized state of cells, delta muH+, required either for electron transfer from cytochrome c to b or for sulfite binding.

Evaluation of diastolic function: old and new methods

Understanding and evaluation of diastolic function have changed with the development of new diagnosis methods. Careful attention to various aspects of diastolic function can provide valuable clinical information regarding the diagnosis for patient's heart failure, estimation of left ventricular filling pressures, optimal management strategy, and prognosis. With the advent of noninvasive hemodynamic methods, the evaluation of diastolic function can be performed routinely as a part of assessment of cardiac function.

Diagnostic value of echocardiography in cardiac tamponade

Cardiac tamponade is a life-threatening condition. Accurate diagnosis and prompt intervention are necessary to prevent adverse outcomes. Clinical features of tamponade such as pulsus paradoxus, tachycardia, elevated jugular venous pressure, and hypotension are important clues to the diagnosis, but are non-specific. Echocardiography allows rapid confirmation of the presence or absence of an effusion, and enables assessment of its hemodynamic impact. Decisions regarding treatment must take into account the clinical presentation and echocardiographic findings. Echocardiographically-guided pericardiocentesis with catheter drainage is the primary treatment strategy of choice for most large or hemodynamically significant effusions. In contemporary clinical practice, echocardiography is the gold standard for diagnosis of tamponade and is essential for directing treatment.

The role of intraoperative transesophageal echocardiography in patients undergoing cardiac mass removal

To evaluate the role of intraoperative transesophageal echocardiography (IOTEE) during surgical removal of cardiac masses, we studied 75 consecutive patients (34 men, aged 56 +/- 16 years, range 17 to 82 years) who underwent surgery primarily for cardiac mass removal with the adjunct of IOTEE for the years 1993 through 1998. The IOTEE provided new information before bypass in 6 patients (8%), altering the planned surgical procedure in all. A newly discovered patent foramen ovale was closed in 2 patients, a second myxoma discovered in one patient, a mitral valve repaired in one patient, inferior vena caval cannulation site clarified in one patient, and in one patient the mass was no longer present and the surgery canceled. In 10 patients (13%), new post-bypass information was found, which prompted return to bypass for valve repair in 3 patients, altered nonsurgical management in 3 patients, and did not necessitate specific measures in 4 patients. Thus, in 75 patients coming to surgery for mass removal, IOTEE affected intraoperative management in 12 (16%).

Clinical utility of Doppler echocardiography and tissue Doppler imaging in the estimation of left ventricular filling pressures: A comparative simultaneous Doppler-catheterization study

BACKGROUND

Noninvasive assessment of diastolic filling by Doppler echocardiography provides important information about left ventricular (LV) status in selected subsets of patients. This study was designed to assess whether mitral annular velocities as assessed by tissue Doppler imaging are associated with invasive measures of diastolic LV performance and whether additional information is gained over traditional Doppler variables.

METHODS AND RESULTS

One hundred consecutive patients referred for cardiac catheterization underwent simultaneous Doppler interrogation. Invasive measurements of LV pressures were obtained with micromanometer-tipped catheters, and the mean LV diastolic pressure (M-LVDP) was used as a surrogate for mean left atrial pressure. Doppler signals from the mitral inflow, pulmonary venous inflow, and TDI of the mitral annulus were obtained. Isolated parameters of transmitral flow correlated with M-LVDP only when ejection fraction <50%. The ratio of mitral velocity to early diastolic velocity of the mitral annulus (E/E') showed a better correlation with M-LVDP than did other Doppler variables for all levels of systolic function. E/E' <8 accurately predicted normal M-LVDP, and E/E' >15 identified increased M-LVDP. Wide variability was present in those with E/E' of 8 to 15. A subset of those patients with E/E' 8 to 15 could be further defined by use of other Doppler data.

CONCLUSIONS

The combination of tissue Doppler imaging of the mitral annulus and mitral inflow velocity curves provides better estimates of LV filling pressures than other methods (pulmonary vein, preload reduction). However, accurate prediction of filling pressures for an individual patient requires a stepwise approach incorporating all available data.

Assessment of cardiac risk before nonvascular surgery: dobutamine stress echocardiography in 530 patients

OBJECTIVE

This study evaluated the incremental value of dobutamine stress echocardiography (DSE) for assessment of cardiac risk before nonvascular surgery.

BACKGROUND

Limited information exists regarding the preoperative assessment of cardiac risk in patients with known or suspected coronary artery disease who are to undergo nonvascular surgery.

METHODS

All patients (303 men, 227 women) who underwent DSE before nonvascular surgery and did not sustain an intervening event (coronary revascularization or cardiac event) were studied. Clinical, electrocardiographic and rest and stress echocardiographic variables were evaluated to identify predictors of postoperative cardiac events.

RESULTS

Events occurred in 6% of patients: 1 cardiac death and 31 nonfatal myocardial infarctions. All of these patients had inducible ischemia on DSE (sensitivity 100%, specificity 63%). Multivariate predictors of postoperative events in patients with ischemia were history of congestive heart failure (p = 0.006; odds ratio = 4.66; confidence interval 1.55 to 14.02) and ischemic threshold less than 60% of age-predicted maximal heart rate (p = 0.0001; odds ratio 7.002; confidence interval 2.79 to 17.61). Clinical variables of Eagle's index identified 21% of patients as low, 68% as intermediate and 11% as high risk preoperatively; the postoperative event rates were 3%, 6%, and 14%, respectively. Dobutamine stress echocardiography identified 60% of patients as low (no ischemia), 32% as intermediate (ischemic threshold 60% or more) and 8% as high risk (ischemic threshold < 60%); postoperative event rates were 0%, 9% and 43%, respectively.

CONCLUSIONS

In this population of patients with known or suspected coronary artery disease evaluated before nonvascular surgery, DSE had incremental value over clinical, electrocardiographic and rest echocardiographic variables for identifying patients at low, intermediate and high risk for postoperative cardiac events. Ischemia occurring at less than 60% of age-predicted maximal heart rate identified patients at highest risk.

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.

Impact of atropine injection on heart rate response during treadmill exercise echocardiography: a double-blind randomized pilot study

We evaluated the effect of atropine on the heart rate (HR) response during treadmill exercise echocardiography. A potential limitation of treadmill exercise echocardiography is the requirement for postexercise imaging. Rapid recovery of HR and wall motion abnormalities may decrease test sensitivity. A double-blind randomized study was performed at a tertiary care center. Fifty-two patients (age, 63 +/- 9 years) with known or suspected coronary artery disease were injected with either 0.5 mg of atropine or saline before treadmill exercise echocardiography. HR response during and after exercise was recorded. Atropine resulted in a greater increase in HR before exercise (increase of 15 +/- 9 vs 5 +/- 7 beats per minute, P < 0.0001) and a higher HR rate during the first 5 minutes of exercise (P < 0.05). In recovery, there was an exponential decrease in HR in both atropine and control groups. However, at the end of image acquisition (66 +/- 15 seconds), the HR was higher in the atropine group (128 +/- 21 vs 115 +/- 19 beats per minute, P = 0.02) and remained higher throughout the 10-minute recovery period (P = 0.0015). Dry mouth was more common after atropine injection (P = 0.005); other side effects were similar. The extent and resolution of myocardial ischemia were comparable in both groups. Atropine injection before treadmill exercise echocardiography results in a higher HR during the acquisition of echocardiographic images; whether atropine could affect the diagnostic accuracy of tread mill exercise echocardiography requires further study.

Calcific constrictive pericarditis: is it still with us?

BACKGROUND

The presence of pericardial calcification on a plain radiograph strongly suggests constrictive pericarditis in patients with heart failure. However, calcific constrictive pericarditis is considered rare in the United States since tuberculosis incidence has decreased, and doubt has therefore been raised about the importance of this radiologic finding in modern cardiovascular practice.

OBJECTIVE

To determine the clinical and prognostic significance of pericardial calcification on radiography in patients with constrictive pericarditis.

DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

A consecutive series of 135 patients (mean age +/- SD, 56 +/- 16 years) who from 1985 through 1995 had constrictive pericarditis confirmed surgically (n = 133) or by autopsy (n = 2). Patients were divided into two groups: those with pericardial calcification on chest radiography (group I) and those without (group II).

MEASUREMENTS

Clinical and diagnostic findings were compared in both groups, and outcome was compared in 132 patients who had pericardiectomy.

RESULTS

Pericardial calcification was seen in 36 patients (27%). The cause of constrictive pericardial disease was indeterminate in 67% of patients in group I and in 21% of patients in group II (P < 0.001). Patients in group I had had symptoms for a longer period and were more likely to have pericardial knock, larger atrial size, and atrial arrhythmia. Significantly more perioperative deaths were seen in group I, but incidence of late survival and incidence of noncalcific disease were similar in both groups.

CONCLUSIONS

Pericardial calcification is a common finding in patients with constrictive pericarditis. It is often associated with idiopathic disease and other markers of disease chronicity and is an independent predictor of increased perioperative mortality rates.