bluuebunny/crossref_metadata_2025 huggingface dataset:
Visual Fields in Short-Toed Eagles, Circaetus gallicus (Accipitridae), and the Function of Binocularity in Birds
Authors: Martin Graham R. , Katzir Gadi
Published: April 2003

Visual fields were determined in alert restrained birds using an ophthalmoscopic reflex technique. The region of binocular overlap is relatively small: maximum width of 20° occurs approximately 15° below the horizontal, and the field extends vertically through 80° with the bill tip placed close to the centre. Monocular field width in the horizontal plane is 139°, and the field is asymmetric about the optic axis. The cyclopean field extends through 260°, and the blind area above and behind the head reaches maximum width of 100° close to the horizontal. At the frontal margins of the monocular field the retinal and optical fields do not coincide; the retinal field margin lies approximately 10° inside the optical margin. This gives rise to an apparent binocular field that is twice the width of the functional binocular field. Interspecific comparisons show that the binocular field of Short-toed Eagles is similar in shape and size to those of bird species that differ markedly in phylogeny, ecology, foraging technique, and eye size. This suggests that these relatively narrow binocular fields are a convergent feature of birds whose foraging is guided by visual cues irrespective of whether items are taken directly in the bill or in the feet, as in eagles, and irrespective of the size and shape of the monocular and cyclopean visual fields. It is argued that binocular vision in birds results from the requirement for each monocular field to extend contralaterally to embody a portion of the optical flow field which is radially symmetrical about the direction of travel. This is in contrast to functional explanations of binocularity, such as those concerned with stereopsis, which present it as a means of extracting higher order information through the combination of two monocular images of the same portion of a scene.
Functional Connectivity among Limbic Brain Areas: Differential Effects of Incubation Temperature and Gonadal Sex in the Leopard Gecko, Eublepharis macularius
Authors: Sakata Jon T. , Coomber Patricia , Gonzalez-Lima F. , Crews David
Published: April 2003

The neural basis of individual differences in behavior has been studied primarily by analyzing the properties of specific neural areas. However, because of the organization of the nervous system, it is also plausible that differences in behavior are mediated by differences in the interactivity or functional connectivity among brain nuclei in particular neural circuits. In the leopard gecko, Eublepharis macularius, the temperature of the egg during incubation not only determines gonadal sex, but also shapes the sociosexual behaviors, reproductive physiology, and hormone sensitivity of adult animals. In this study the effects of both incubation temperature and gonadal sex on functional connectivity among limbic brain areas were examined. Functional connectivity was assessed by analyzing covariance patterns in metabolic capacity, as revealed by quantitative cytochrome oxidase histochemistry. It was hypothesized that incubation temperature and gonadal sex affect the propensity to display aggressive or sexual behaviors by altering the functional connectivity within relevant neural circuits. The correlations of metabolic capacity between the anterior hypothalamus and both the septum and preoptic area were significant only in relatively aggressive individuals, suggesting that these circuits may regulate the phenotypic variation in aggressiveness caused by incubation temperature. The correlations between the ventromedial hypothalamus and both the dorsal ventricular ridge and septum were significant only in females, suggesting that these circuits may modulate female-typical sexual behaviors. Correlations among preoptic, hypothalamic and amygdalar areas tended to be distributed across both sexes, suggesting that there may be shared pathways underlying the expression of male-typical and female-typical behaviors.
Retinal Ganglion Cell Topography in Elasmobranchs
Authors: Bozzano Anna , Collin Shaun P.
Published: April 2003

Retinal wholemounts are used to examine the topographic distribution of retinal cells within the ganglion cell layer in a range of elasmobranchs from different depths. The retina is examined for regional specializations for acute vision in six species of selachians, Galeocerdo cuvieri, Hemiscyllium ocellatum, Scyliorhinus canicula, Galeus melastomus, Etmopterus spinax, Isistius brasiliensis, one species of batoid, Raja bigelowi and one species of chimaera, Hydrolagus mirabilis. These species represent a range of lifestyles including pelagic, mesopelagic and benthic habitats, living from shallow water to the sea bottom at a depth of more than 3000 m. The topography of cells within the ganglion cell layer is non-uniform and changes markedly across the retina. Most species possess an increased density of cells across the horizontal (dorsal) meridian or visual streak, with a density range of 500 to 2,500 cells per mm2 with one or more regional increases in density lying within this specialized horizontal area. It is proposed that the higher spatial resolving power provided by the horizontal streak in these species mediates panoramic vision in the lower frontal visual field. Only I. brasiliensis possesses a concentric arrangement of retinal iso-density contours in temporal retina or an area centralis, thereby increasing spatial resolving power in a more specialized part of the visual field, an adaptation for its unusual feeding behavior. In Nissl-stained material, amacrine and ganglion cell populations could be distinguished on the criteria of soma size, soma shape and nuclear staining. Quantitative analyses show that the proportion of amacrine cells lying within the ganglion cell layer is non-uniform and ranges between 0.4 and 12.3% in specialized retinal areas and between 8.2 and 48.1% in the peripheral non-specialized regions. Analyses of soma area of the total population of cells in the ganglion cell layer also show that the pelagic species possess significantly smaller soma (9–186 μm2) than benthic and/or deep-sea species (16–338 μm2), and that a number of different morphological classes of cells are present including a small population of giant ganglion cells.
Visual System Labeled by c-Fos Immunohistochemistry after Light Exposure in the ‘Blind’ Subterranean Zambian Mole-Rat (Cryptomys anselli)
Authors: Oelschläger Helmut H.A. , Nakamura Makoto , Herzog Matthias , Burda Hynek
Published: April 2003

The Zambian mole-rat (Cryptomys anselli) is a rodent that lives and forages underground, and under natural conditions is rarely, if ever, exposed to light. Its eye is organized as in other rodents and is prominent but minuscule. The animals do not seem to react to light behaviorally or to orient visually, although exact physiological and/or behavioral experiments have not been conducted to date. Nuclear expression of transcriptional regulatory protein (c-Fos) as a marker of cell activity was studied immunohistochemically in five mole-rats exposed to bright light for 1 h after 3 days in constant darkness, and in four non-stimulated control animals that were kept in darkness for three days and then killed under deep anesthesia. The retinae and retino-recipient areas of non-stimulated animals remained unlabeled, but many of these structures showed strong c-Fos expression bilaterally [retina, dorsal lateral geniculate body (DLG), olivary pretectal nucleus, retrosplenial cortex, neocortex] in light-exposed animals. In contrast, the suprachiasmatic nucleus did not seem to be affected by light stimuli during the experiment. In both light-stimulated and control animals the rudimentary superior colliculus exhibited slight immunoreactivity. Interestingly, the olivary pretectal nucleus, which in mammals is involved in light/dark discrimination, as well as the DLG as part of the image-forming visual system were consistently labeled by c-Fos after light stimulation, indicating that vision in Cryptomys possibly plays a more significant role than previously assumed.
Sonic/Vocal Motor Pathways in Squirrelfish (Teleostei, Holocentridae)
Authors: Carlson Bruce A. , Bass Andrew H.
Published: April 2003

Similar to many teleost fish, squirrelfish (family Holocentridae) produce vocalizations by the contraction of muscles that lead to vibration of the swimbladder. We used biotinylated compounds to identify the position and extent of vocal motor neurons in comparison to additional motor neuron groups, namely those of red and white dorsal epaxial muscle and opercular muscle that are located adjacent to or near the sonic muscle. The sonic motor nucleus (SMN) was located in the caudal medulla and rostral spinal cord in a ventrolateral position with dendrites extending dorsally in a dense bundle along the lateral edge of the medulla and axons exiting via ventral occipital nerve roots. Transneuronal transport of biocytin identified premotor neurons within the SMN and in the medially adjacent reticular formation that projected to the contralateral SMN and more rostrally to the octavolateralis efferent nucleus and nucleus praeeminentialis, suggesting interactions between vocal and octavolateralis systems as seen in other teleosts. Motor neurons innervating the red and white dorsal muscle formed a loose aggregate in the dorsal motor column, adjacent to the medial longitudinal fasciculus, sending fibers bilaterally throughout the spinal cord with axons exiting via ventral spinal nerve roots. Opercular motor neurons were located within the facial motor nucleus. The anatomical characteristics of the SMN of squirrelfish, a representative member of the order Beryciformes, are similar to those of representative members of the closely related order Scorpaeniformes, but diverge from the SMN of more distantly related orders of paracanthopterygiian and ostariophysan teleosts. These results therefore suggest a possible homology among the SMNs of acanthopterygiian fishes.
Analysis of the P Wave with Signal Averaging to Assess the Risk of Atrial Fibrillation after Coronary Artery Bypass Surgery
Authors: Dimmer Carlo , Jordaens Luc , Gorgov Nick , Peene Isabelle , François Katrien , van Nooten Guido , Clement Denis L.
Published: April 2003

P wave signal averaging was performed in 91 consecutive patients undergoing coronary artery bypass grafting to detect patients at risk of postoperative atrial fibrillation (AF). Sixteen patients (17.5%) developed AF after surgery. The P wave duration on the signal-averaged electrocardiogram (ECG) and on surface ECG was prolonged in AF patients compared to others (respectively 141 ± 12 vs. 132 ± 12 ms and 124 ± 9 vs. 113 ± 9 ms). The root mean square voltages (RMS) of the total P wave were not different between the two groups; the RMS of the late portion of the P wave (late RMS) was significantly higher (0.25 ± 0.15 vs. 0.17 ± 0.10 µV) and the RMS of the first 110 ms of the P wave (early RMS) significantly lower (0.88 ± 0.28 vs. 1.09 ± 0.33 µV) in AF. The late/early RMS ratio was different (0.29 ± 0.16 vs. 0.17 ± 0.11). In a multivariate analysis only age and the late/early RMS ratio were predictive for AF.
Clinical Significance of Hypoxemia without Congestive Heart Failure in Patients Presenting with Acute Myocardial Infarction
Authors: Aoki Nobuo , Yanagisawa Atsuo , Shimoyama Katsuya , Taniuchi Masato , Fujita Hiroshi , Mizuno Haruyoshi , Yoshino Hideaki , Ishikawa Kyozo
Published: April 2003

This study investigated the clinical significance of hypoxemia without apparent clinical congestive heart failure in patients with acute myocardial infarction (AMI). Sixty-two patients with AMI of the Killip group I and Forrester subset I state were stratified into a hypoxemia group and a normoxemia group. The increase in the neutrophil count and the severity of the coronary artery disease as graded by Gensini’s score were significantly higher in the hypoxemic group. The cardiac index was lower in hypoxemic than normoxemic patients. Myocardial scintigraphy revealed no acute difference in defect scores (DS) or left ventricular ejection fraction (LVEF) between the two groups, but DS was significantly higher (p < 0.01) and LVEF was lower (p < 0.01) in the hypoxemic group 2 years after infarction. Patients with hypoxemia have a more severe angiographic coronary pathology than normoxemic patients, and latent cardiac hypofunction occurs.
Diastolic Time during Weight Carrying Exercise in Patients with Myocardial Infarction
Authors: Takehana Kazuya , Sugiura Tetsuro , Nagahama Yo , Inada Mitsuo , Iwasaka Toshiji
Published: April 2003

Cardiovascular responses to static-dynamic exercises were studied in 27 patients with recent myocardial infarction. Patients with ischemic electrocardiographic changes at peak weight carrying exercise (group 1 = 8 patients) had a significantly larger left ventricular end-diastolic volume than those without (group 2 = 19 patients). A higher tension time index and shortening of diastolic time/min was observed in group 1 compared to group 2 during weight carrying. Thus, in addition to the increased myocardial oxygen demand, shortening of the diastolic perfusion time was observed during static-dynamic exercise in patients with dilated heart after myocardial infarction.
Electrophysiological Evidence of Reinnervation of the Transplanted Human Heart
Authors: Wesche Jarlis , Orning Otto , Eriksen Morten , Walløe Lars
Published: April 2003

Beat-by-beat heart rate (HR) changes during exercise were studied in two young and fit heart-transplanted humans at different time intervals following transplantation. Upon the start of the exercise, a slow gradual increase in HR was seen during the early experiments after the transplantation, whereas an immediate rapid increase in HR was observed during the later experiments. From standard ECGs obtained 32 months after transplantation, two P waves at somewhat different rates could be identified in both subjects, probably arising from donor and recipient sinoatrial nodes, respectively. The two P wave rate changes during and following exercise were very similar. We conclude that these changes in the HR pattern and ECG must be due to reinnervation of the donor hearts, most likely by parasympathetic cardiac fibers.
Symptom-Oriented Nitrate Administration and Survival after Acute Myocardial Infarction
Authors: Marmor Alon , Gottlieb Shmuel , Hod Hanoch , Boyko Valentina , Behar Solomon
Published: April 2003

The effect of nitrates during evolving myocardial infarction is controversial. While previous studies showed that nitrates improve left ventricular function and have a beneficial effect on survival, two recent randomized megatrials showed that nitrates did not alter mortality after acute myocardial infarction (AMI). The present study analyzes the use of nitrates in clinical practice and their impact on mortality in a cohort of unselected consecutive AMI patients admitted to all 25 coronary care units operating in Israel during 2 months in 1994. Among 966 patients in Killip class I–III on admission, 81% (n = 783) received nitrate therapy by intravenous infusion or orally. Baseline characteristics of patients treated with or without nitrates were quite similar. Seven-day mortality was markedly reduced in the nitrate-treated group (5 and 11%, p < 0.001) in comparison with those who did not receive nitrates. After adjustment for pertinent variables the 7-day relative risk (RR) of mortality was 0.51 [95% confidence interval (CI) 0.25–1.07; p = 0.08], whereas, the 7-day to 1-year mortality after AMI was not altered by nitrate use (RR = 0.97; 95% CI 0.56–1.68; p = 0.92). Nitrate therapy remains a widespread and a valid symptom-oriented therapeutic approach, especially early after AMI, in the community.
Dynamic Three-Dimensional Echocardiography Using Parallel Slicing: A Promising Diagnostic Procedure in Adults with Congenital Heart Disease
Authors: Bartel Thomas , Müller Silvana , Erbel Raimund
Published: April 2003

In 18 of 77 adult patients presenting with congenital heart disease, three-dimensional conceptualization was found to be insufficient using two-dimensional echocardiographic imaging. In these individuals, three-dimensional image reconstruction from digitized parallel images was carried out, providing additional information in 14 of them. Three-dimensional echocardiography and volumetry may, especially in patients with atrial septal defect, cor triatriatum and corrected transposition of the great arteries, be an asset amplifying the diagnostic information yielded by conventional two-dimensional echocardiographic approaches.
Pseudo-Pseudoaneurysm of the Left Ventricle
Authors: Singh B.K. , Greene A.L. , Ritchie M.E.
Published: April 2003

Left ventricular pseudoaneurysms are an uncommon complication of myocardial infarction and need urgent surgical repair. Though it is critical that they be accurately identified, pseudoaneurysms are occasionally misdiagnosed. We report an abnormality which may be mislabeled a pseudoaneurysm which we term a pseudo-pseudoaneurysm. The approach to accurate diagnosis of pseudoaneurysms is discussed.
Low Serum Cholesterol Levels Predict High Perioperative Mortality in Patients Supported by a Left-Ventricular Assist System
Authors: Richartz Barbara M. , Radovancevic Branislav , Frazier O. Howard , Vaughn William K. , Taegtmeyer Heinrich
Published: April 2003

Background: Although the use of a left-ventricular assist system (LVAS) provides circulatory support for end-stage heart failure patients awaiting heart transplantation, this procedure is accompanied by a relatively high perioperative mortality. The aim of this retrospective study was to identify those patients preoperatively which have the highest perioperative mortality. Methods and Results: Forty-five consecutive patients undergoing LVAS implantation were evaluated for preoperative risk factors, including body mass index, hemodynamic data, and blood chemistry studies by multivariate analysis. They were divided into (1) patients who were successfully transplanted (n = 25) and (2) patients who died before transplantation (n = 20). The nonsurvivors were subclassified into patients who died within 14 days after surgery (n = 11) and patients who died after 2 weeks of device implantation (n = 9). Hemodynamic parameters were the same in both groups, but total cholesterol was significantly lower in the nonsurvivors than in the survivors (90 ± 7 vs. 144 ± 8 mg/dl, respectively, p < 0.0001). The sensitivity of predicting perioperative death with a serum cholesterol below 100 mg/dl was 100%, the specificity of predicting survival with a serum cholesterol above 120 mg/dl was 87%. Conclusion: In this small retrospective study, there was a correlation between total cholesterol levels and survival of patients with advanced heart failure on mechanical support. A cholesterol level below 100 mg/dl was accompanied by a high perioperative mortality. In contrast, a cholesterol level above 120 mg/dl was accompanied by a 87% chance of survival. The results suggest a predictive value of cholesterol which is independent of the hemodynamic status.
Comparison of S–T Segment/Heart Rate Slope with Exercise Thallium Imaging and Conventional S–T Segment Criteria in Detecting Coronary Artery Disease: Effect of Exercise Level on Accuracy
Authors: Liu Yen-Bin , Huang Por-Jau , Su Cheng-Tau , Chieng Poon-Ung , Wu Chau-Chung , Ho Yi-Lwun
Published: April 2003

The S–T segment/heart rate (ST/HR) slope has been proposed as a more accurate electrocardiographic criterion for the diagnosis of coronary artery disease, but studies comparing the diagnostic value of the ST/HR slope with exercise thallium imaging are scant. The aims of this study were to assess the diagnostic accuracy of the ST/HR slope, conventional S–T segment criteria and exercise thallium imaging in detecting coronary artery disease and to evaluate the effect of exercise level on the sensitivity and specificity of these three techniques. Ninety consecutive patients underwent treadmill testing and exercise thallium single-photon emission computed tomography (SPECT) simultaneously. All 90 patients also underwent coronary angiography within 1 month of the exercise test. We found that exercise thallium SPECT had a significantly higher diagnostic accuracy than either the ST/HT slope or conventional S–T segment criteria (thallium imaging 82%, ST/HR slope 67%, conventional S–T segment criteria 63%). The overall accuracy of the ST/HR slope was slightly but insignificantly greater than conventional S–T segment criteria (ST/HR slope 67%, conventional S–T segment criteria 63%; p = 0.639). In 50 patients with a lower exercise level, defined as not achieving 85% of their maximal predicted heart rate, the accuracy of the ST/HR slope was insignificantly greater (ST/HR slope 72%, conventional S–T segment criteria 66%; p = 0.517). In 40 patients with adequate exercise, the accuracy rate was the same (60%) for both the ST/HR slope and conventional S–T segment criteria. We conclude that exercise thallium imaging is more accurate than the ST/HR slope in diagnosing coronary artery disease and that the accuracy of the ST/HR slope is marginally better than conventional S–T segment criteria only in patients with a lower exercise level, and not in those with adequate exercise.
Assessment of Functional Results after Percutaneous Transluminal Coronary Angioplasty by Cardiopulmonary Exercise Test
Authors: Klainman Eliezer , Fink Gershon , Lebzelter Joseph , Zafrir Nily
Published: April 2003

Twenty-nine patients with documented coronary artery disease underwent cardiopulmonary exercise tests before and following a percutaneous transluminal coronary angioplasty (PTCA). The patients medication regimen and exercise protocols remained the same in both cases. Following PTCA, significant improvement (p < 0.001–0.0001) was noted in oxygen consumption (1,526.8 ± 470.0 vs. 1,686.2 ± 390 ml/min), oxygen pulse (12.40 ± 2.73 vs. 13.44 ± 2.9 ml/beat), oxygen pulse score (7.62 ± 1.29 vs. 8.85 ± 1.26 points) and in the ventilatory anaerobic threshold (993.1 ± 177.6 vs. 1,089.8 ± 150.9 ml/min) but not (p > 0.05) in maximal heart rate (128.7 ± 16.9 vs. 132.0 ± 17.2 beats/min). Thus, a cardiopulmonary exercise test is an effective method to assess functional results following PTCA.
A Comparison of the Effects of Mibefradil and Atenolol on Regression of Left Ventricular Hypertrophy in Hypertensive Patients
Authors: Höglund Christer , Cifkova Renata , Mimran Albert , Tenczer Jozsef , Watt Andrew , Wilkins Martin R. , Lindberg Elisabeth
Published: April 2003

Objective: This study was designed to compare the effect of mibefradil, a selective T-type calcium channel antagonist, with the β-blocker atenolol on regression of left ventricular (LV) hypertrophy in hypertensive patients. Methods: In this multicenter, double-blind, active-controlled, randomized, parallel-group comparison, 66 patients with mild-to-moderate hypertension (sitting diastolic blood pressure, SDBP, 95–114 mm Hg) and LV mass index >102 g/m2 for males and >88 g/m2 for females were randomized to an initial treatment with 50 mg of either mibefradil or atenolol for 4 weeks. Doses were increased to 100 mg/day if blood pressure was not normalized to ≤90 mm Hg, and, if needed, 25 mg of hydrochlorothiazide was added. Treatment continued for a total of 24 weeks. LV hypertrophy was assessed by echocardiography, and trough SDBP and adverse events were recorded. Results: Treatment with mibefradil or atenolol resulted in decreases from baseline in LV mass index of 11.1% (p < 0.001) and 9.1% (p < 0.001), respectively. The treatment difference (mibefradil vs. atenolol) was not statistically significant. Reductions in SDBP with mibefradil and atenolol were 14.3 and 10.7 mm Hg, respectively, again not statistically significant. Both drugs were well tolerated; however, overall there were more potentially drug-related adverse events reported with atenolol (48.5%) than with mibefradil (24.2%). Conclusions: The reductions in LV hypertrophy and blood pressure achieved with mibefradil were larger but statistically equivalent to those with atenolol, but a lower overall incidence of treatment-related adverse events was seen in the mibefradil-treated patients.
Atrial Fibrillation: A Delayed Presentation of Traumatic Tricuspid Valve Incompetence
Authors: Singer Igor , Dawn Buddhadeb , Calzada Norberto , Spence Paul A.
Published: April 2003

Isolated tricuspid valve incompetence resulting from blunt thoracic injury is rare. The diagnosis may be challenging. Subsequent clinical course may be variable. Early surgical intervention rather than medical therapy has been suggested in selected cases. We report a case of blunt chest trauma causing delayed chronic tricuspid regurgitation manifesting primarily as atrial fibrillation many years after the initial blunt chest trauma. Replacement of tricuspid valve restored normal sinus rhythm.
Renal Hypersensitivity to Vasopressin in Congestive Heart Failure
Authors: Wong Bonita P.H. , Wong Norman L.M.
Published: April 2003

Plasma vasopressin (AVP) levels are often elevated in congestive heart failure (CHF). To determine the significance of AVP in CHF, we performed clearance studies on the UM-X7.1 strain of cardiomyopathic (CM) hamsters with moderate heart failure and age-matched healthy controls. Exogenous AVP or a selective V2 agonist (0.3 ng·kg–1·min–1) reduced the fractional excretion of sodium (FENa) and water (FEH2O) by 40–46% in the control group. Although the CM hamsters exhibited a blunted physiological response to the V2 agonist, their urinary cAMP levels were fivefold that of normal and reflect an altered regulation of V2 receptor signalling during CHF. Additional studies also showed that infusion of a V2 antagonist (0.3 ng·kg–1·min–1) produced natriuresis and diuresis in CM hamsters (FENa: 7.9 ± 1.1 vs. 4.8 ± 0.6%, p < 0.05; FEH2O: 2.2 ± 3 vs. 1.5 ± 0.2%, p < 0.05) but did not decrease fluid reabsorption in the normal hamsters. In conclusion, the attenuated renal response to exogenous AVP in CM hamsters may be attributed to an enhanced endogenous AVP response during CHF.
Histopathological Correlates of Early Arterial Recoil following Directional Coronary Atherectomy
Authors: Dangas George , Peters-Veluthamaningal Cyriak , Cocke Thomas P. , Vidhun Raghuraman , Duvvuri Srinivas , Marmur Jonathan D. , Sharma Samin K.
Published: April 2003

Elastic recoil has been implicated in the pathophysiology of restenosis after conventional balloon angioplasty alone. Directional atherectomy may attenuate arterial recoil by removing the internal elastic lamina and medial smooth muscle cells and altering the vessel wall architecture. This study sought to evaluate early recoil after directional atherectomy and its relation with excision of deep arterial wall structures. We prospectively evaluated the correlation of the histopathologic evidence of media or adventitia as assessed in the atheroma retrieved during the procedure with the early changes in minimal lumen diameter after directional atherectomy followed by adjunct balloon dilatation in 50 consecutive cases. Recoil was assessed by routinely performed 1- and 15-min postprocedure angiograms, and patients were divided into two groups according to the absence (group I, n = 26) or presence (group II, n = 24) of recoil. The mean changes in minimal luminal diameter between 1 and 15 min was +0.22 mm in group I and –0.14 mm in group II. The absence of recoil was strongly associated with evidence of media tissue in the pathologic analysis as compared with cases with recoil (42 vs. 18%, respectively; p = 0.02). Similarly, retrieval of adventitia was seen exclusively in the group without recoil (15 vs. 0%; p = 0.06). Vessels that underwent recoil had significantly larger reference and immediate postprocedure minimal luminal diameters (3.62 ± 0.57 and 3.02 ± 0.45 mm, respectively) as compared with arteries with no recoil (3.28 ± 0.35 and 2.75 ± 0.43 mm, respectively; p < 0.05 for both). Therefore, early luminal changes, likely related to elastic recoil, correlated with excision of deep wall structures during directional atherectomy. Arteries that showed recoil were larger, possibly due to thicker muscular layer and/or larger plaque burden as compared with arteries that did not recoil. Thus, optimal tissue debulking during directional atherectomy appears to attenuate recoil, providing an additional insight into the mechanism of action of this percutaneous revascularization device.
Plasma B-Type Natriuretic Peptide Measurement in a Multiphasic Health Screening Program
Authors: Niinuma Hiroyuki , Nakamura Motoyuki , Hiramori Katsuhiko
Published: April 2003

The aim of this study was to determine whether measurement of plasma levels of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) is an efficacious method to predict patients with heart disease irrespective of left ventricular function in a multiphasic health screening program. We have examined whether patients with various heart disease selected by physical examination, ECG, and chest X-rays can be identified by plasma levels of ANP and BNP. We examined 481 consecutive subjects who visited our checkup clinic for a multiphasic health screening test. By routine methods, among the 481 subjects, 13 were found to have some form of heart disease (old myocardial infarction, 2; cardiomyopathy, 2; valvular heart disease, 2; hypertensive heart disease, 5, and lone atrial fibrillation, 2). Sensitivity, specificity, and quintile analysis for identification of the patients with heart disease were determined by various cutoff levels of plasma ANP and BNP. Receiver operating characteristic (ROC) curves were constructed for the identification of these patients. A plasma BNP level of 40 pg/ml had a sensitivity of 85% and a specificity of 92% for heart disease detection. The area under the ROC curve for BNP was significantly greater than that for ANP (0.94 vs. 0.81; p < 0.001). A plasma BNP level of 13 pg/ml or less gave a 100% negative prediction value for heart disease. Plasma BNP concentration is a useful biochemical marker for the screening of asymptomatic patients with heart disease due to various etiologies from large population samples.
Fibrosis, Myocyte Degeneration and Heart Failure in Chronic Experimental Aortic Regurgitation
Authors: Liu Si-Kwang , Magid Norman R. , Fox Philip R. , Goldfine Steven M. , Borer Jeffrey S.
Published: April 2003

Myocardial fibrosis and myocyte degeneration have been reported in patients with chronic aortic regurgitation (AR), and may be related to the pathophysiology of congestive heart failure (CHF) in this disease. To define the relationship between myocardial histopathologic variations and CHF in chronic AR, we performed gross and microscopic evaluations of postmortem tissue from a rabbit model of chronic AR manifesting left ventricular (LV) responses to AR similar to those in humans. Moderate-to-severe chronic AR (echocardiographic regurgitant fraction = 52 ± 13%) was induced by closed-chest aortic valve perforation in 11 New Zealand White rabbits; 5 control rabbits were sham operated. Six of the 11 AR rabbits died 1.5 ± 0.8 years (range 0.6–2.8 years) after AR induction; all 6 had gross and histologic anatomic evidence of CHF at necropsy. The remaining 5 AR rabbits survived until sacrifice at 2.9 ± 0.1 years of AR; none had pathologic evidence of CHF. Cardiac hypertrophy and the extent of LV fibrosis and myocyte necrosis all were greatest among the 6 AR CHF rabbits. No inflammatory response was apparent in any animal. Moderate-to-severe chronic experimental AR frequently results in CHF which is strongly associated with myocardial fibrosis and necrosis, without evidence of inflammation. These histopathologic variations may be pathophysiologically related to CHF development.
Thallium-201 for Detection of Myocardial Viability: Comparison of Early Postexercise Reinjection and Imaging with 4 and 18–24 Hours Redistribution Imaging
Authors: Antonopoulos Athanassios , Georgiou Evangelos , Kyriakidis Michael , Nikolopoulos Dimitrios , Proukakis Charalambos , Toutouzas Pavlos
Published: April 2003

To evaluate the efficacy of an early 201Tl reinjection and imaging protocol for reducing the need for conventional 4-hour or optimal 24-hour redistribution imaging (RI) and detecting of myocardial viability, we compared the results of early postexercise Tl reinjection and imaging with those of 4- and 24-hour RI in 74 consecutive patients aged 55 ± 9 years (mean ± SD) who were assessed for myocardial ischemia. One millicurie of Tl was injected promptly after completion of the initial postexercise imaging (PEX) and three additional sets of images were acquired 1, 4 and 18–24 h later. A total of 2,368 segments were evaluated. On PEX, 390 (17%) segments showed defects, of which 287 (74%) showed enhanced Tl uptake at 1-hour RI; 89 (23%) did not change and 14 (4%) showed reverse redistribution. Of the 103 persistent defects, only 27 (7%) showed further fill-in of Tl; 62 (16%) segments showed reverse redistribution at 4-hour RI while at 18- to 24-hour RI 17 (4%) and 47 (12%) segments showed further fill-in of Tl and reverse redistribution, respectively. Finally, after analysis of 4- and 18- to 24-hour RI, the diagnosis changed from myocardial necrosis to ischemia in only 2 (3%) patients. In conclusion, these results suggest that by eliminating the need for an additional delayed set of images for detection of myocardial viability, this protocol reduces the total investigation procedure, is more convenient for the patient, increases patient turnover and expedites the decision-making process.
Regional and Temporal Nonuniformity of Shape and Wall Movement in the Normal Left Ventricle
Authors: Barletta G. , Baroni M. , Del Bene R. , Toso A. , Fantini F.
Published: April 2003

Asymmetry of left ventricular (LV) shape and asynchrony of regional LV movement have been described in the normal human heart, but never correlated to each other. In 16 normal subjects, right anterior oblique ventriculography was used to obtain volumes, regional wall motion (centerline method) and curvature (windowed Fourier series approximation of contours) over the entire cardiac cycle. The apex had the greatest curvature, while the posterior wall had a negative end-diastolic curvature that decreased further at early-systole and became positive at end-systole. The anterior region had the greatest and the anteroapical region the least fractional shortening. Asynchrony was evident as a delayed contraction of the infero- and anteroapical regions, and as a greater rate of late-systolic shortening of the anterior wall than that of the apex. Shape changes and shortening were dyssynchronous in the apical regions where the greatest changes occurred at early diastole. Temporal and regional nonuniformity of shape and movement exists in normal subjects. Dyssynchrony between shape and regional contraction of the apical regions deserves further studies.
Are There Differences among Patients with Inferior Acute Myocardial Infarction with ST Depression in Leads V2 and V3 and Positive versus Negative T Waves in These Leads on Admission?
Authors: Porter Avital , Vaturi Mordechai , Adler Yehuda , Sclarovsky Samuel , Strasberg Boris , Herz Izhak , Kuzniec Haim , Birnbaum Yochai
Published: April 2003

We assessed whether there are differences among patients with inferior acute myocardial infarction and ST segment depression in leads V2–V3 between those with positive versus negative T waves on admission. We found no differences in the prevalence of concomitant significant left anterior descending coronary artery stenosis and anterior or posterior wall motion abnormalities on echocardiography between the two groups. Precordial ST segment depression with negative T wave may be the early electrocardiographic pattern of posterior infarction, reflecting ST segment elevation with positive T waves that would have been detected by leads facing the posterior wall.
Subacute Stent Thrombosis Occurring More Than One Month after Implantation for Acute Myocardial Infarction
Authors: La Vecchia Luigi , Bedogni Francesco , Vincenzi Mario
Published: April 2003

Two patients are described with anterior acute myocardial infarction who had a successful recanalization of a totally occluded left anterior descending coronary artery by means of primary angioplasty and stenting. Reinfarction occurred more than 1 month after implantation. At angiography, a totally occluded left anterior descending coronary artery at the site of stenting was observed and was effectively reopened with angioplasty and stenting in both cases. This report aims to emphasize that acute myocardial infarction still represents a major risk factor for subacute stent thrombosis and that this potentially catastrophic event may occur late after implantation. Potential implications for revascularization strategies and medical treatment are discussed.
Extracellular Amino Acids as Markers of Myocardial Ischemia during Cardioplegic Heart Arrest
Authors: Kennergren Charles , Mantovani Vittorio , Lönnroth Peter , Nyström Britta , Berglin Eva , Hamberger Anders
Published: April 2003

Extracellular levels of amino acids in the myocardial interstitium are sensitive indicators of myocyte function. Lowered ATP leads to a rapid extracellular appearance of amino acids with a high intra- to extracellular concentration ratio, such as taurine and glutamate. Nitrogen fluxes are reflected by glutamine, while alanine, glycine, serine and leucine are markers of proteolysis. In addition, degradation of membrane phospholipids is reflected by other primary amines, such as phosphoethanolamine. The time course of these changes was determined before, during and after cardioplegic heart arrest. Two regions of the heart were monitored in 20 patients by means of microdialysis sampling. After only 20 min of heart arrest, extracellular taurine, glutamate and phosphoethanolamine increased transiently up to 25 times the basal level. Ten–20 min later, glutamine increased by 6 times. A doubling of alanine, glycine, serine and leucine levels took place 30 min after release of the aortic cross-clamp. After 2 h, all were at levels similar to those recorded 15–30 h later. Levels of taurine and glutamate in the anterior wall of the heart correlated significantly with those of its lateral wall. The response to surgery and heart arrest was studied in a group of patients with ischemic heart disease as well as in another group of patients, who underwent heart surgery for nonischemic reasons. The response of taurine and glutamine was significantly higher for the patients with ischemic heart disease, in spite of a shorter mean time of heart arrest. No sex differences were recorded. High levels of amino acids coincided frequently with clinical events, which were suggestive of ischemia, but were also recorded in a few patients without diagnosed events. We conclude that monitoring of extracellular amino acids is valuable for evaluation and development of cardioprotective strategies.
Bolus versus Continuous Low Dose of Enalaprilat in Congestive Heart Failure with Acute Refractory Decompensation
Authors: Podbregar M. , Voga G. , Horvat M. , Žuran I. , Krivec B. , Skale R. , Parežnik R.
Published: April 2003

The first dose of angiotensin-converting enzyme (ACE) inhibitors may trigger a considerable fall of blood pressure in chronic heart failure. The response may be dose-related. To determine hemodynamic and systemic oxygenation effects of low-dose enalaprilat, we administered intravenous enalaprilat (0.004 mg/kg) as bolus (group B) or continuous 1-hour infusion (group C) in 20 patients with congestive heart failure due to ischemic heart disease with acute decompensation refractory to inotropic, vasodilator and diuretic therapy. Hemodynamic and systemic oxygenation variables were recorded at baseline (+0 min), +30, +60, +120, +180, and +360 min after the start of intervention. Mean arterial pressure (MAP) (p < 0.001), mean pulmonary artery pressure (MPAP) (p < 0.001), pulmonary artery occlusion pressure (PAOP) (p < 0.001), oxygen extraction ratio (ER) (p < 0.026) decreased regardless of enalaprilat application. Compared to group B, there was in group C prolonged decrease of MAP, MPAP, PAOP, ER and increase of pulmonary artery oxyhemoglobin saturation in regard to baseline values. Cardiac index, heart rate, central venous pressure and oxygen consumption index did not change. A low dose of intravenous enalaprilat (0.004 mg/kg) can be used to safely improve hemodynamics and systemic oxygenation in congestive heart failure due to ischemic heart disease with acute refractory decompensation.
Time Course of Endothelin-1 Plasma Level in Patients with Acute Coronary Syndromes
Authors: Vojáček Jan , Kolář Jiří , Lisý Ondřej , Hraboš Vladimír , Šimek Stanislav , Jindra Jr. Antonín , Jáchymová Marie
Published: April 2003

An elevated plasma level of endothelin-1 was reported in several cardiovascular conditions including unstable angina pectoris and myocardial infarction. The present study was designed to evaluate the time course of the endothelin-1 release in unstable angina pectoris and to assess its relationship to the development of myocardial infarction and coronary vessel occlusion. The cohort studied included 32 patients with the clinical diagnosis of unstable angina pectoris who had been admitted to the coronary care unit and subsequently underwent coronary angiography (group A). Fourteen patients with chronic stable angina pectoris referred to routine diagnostic coronary angiography served as the control group (group B). A significant difference in the endothelin-1 plasma level was found between both groups, the values being 10.2 ± 5.3 and 6.0 ± 3.1 pg/ml (p < 0.01), respectively. There were, however, no significant differences between the following subdivisions of group A: patients with and without subsequent myocardial infarction; those with angiographically documented occlusion of at least one major branch of the coronary artery and no occlusion; and finally, those with persisting symptoms of angina pectoris and with favorable response to treatment. Neither was there any difference found among the subgroups differing in the time interval between the onset of chest pain and blood sampling. The time course of endothelin plasma concentrations showed elevated values lasting for more than 96 h after the index episode of prolonged chest pain. No correlation with the subsequent clinical course could be inferred. Thus, plasma endothelin level was elevated in patients with unstable angina pectoris and myocardial infarction and the increase persisted for several days after the onset of symptoms.
Atrial Involvement in Patients with Progressive Systemic Sclerosis: Relationship between Ultrasonic Tissue Characterization of the Atrium and Interatrial Conduction
Authors: Mizuno Reiko , Fujimoto Shinichi , Nakano Hiroshi , Nakajima Tamio , Kimura Asako , Nakagawa Yoshihito , Dohi Kazuhiro
Published: April 2003

Objective: The aim of this study was to assess atrial lesions using ultrasonic tissue characterization and to determine the contribution of atrial lesions to the interatrial electromechanical coupling conduction time in patients with progressive systemic sclerosis (PSS). Methods: Twenty patients with PSS and 20 age-matched healthy controls were evaluated. The cyclic variation in integrated backscatter value (CV-IB) was measured at the interatrial septum (IAS) from apical four chamber view. M-modes of ventricular long axis motion along with phono- and electrocardiograms were recorded simultaneously at the right lateral (RT) and left lateral (LT) sites of the atrioventricular (AV) rings and central fibrous body (CFB) in the apical four-chamber view. Intervals from the P wave on ECG to the echocardiographic onset of atrial contraction as a point of inflection in long axis M-mode echocardiogram were measured at the RT and LT sites of AV rings and CFB (P-RT, P-LT, P-SEP, respectively). Interatrial electromechanical coupling conduction time was determined as [(P-LT) – (P-RT)]. Results: In patients with PSS compared to normal controls, P-RT, P-SEP, P-LT, and interatrial conduction time were greater, while CV-IB in IAS decreased. Furthermore, CV-IB in IAS correlated well with interatrial conduction time (r = 0.7, p < 0.01) in patients with PSS. Conclusions: Interatrial electromechanical coupling times may be prolonged due to atrial tissue damage in patients with PSS.
The Cost-Effectiveness of Losartan versus Captopril in Patients with Symptomatic Heart Failure
Authors: Dasbach Erik J. , Rich Michael W. , Segal Robert , Gerth William C. , Carides George W. , Cook John R. , Murray James F. , Snavely Duane B. , Pitt Bertram
Published: April 2003

The Losartan Heart Failure ELITE Study recently found that in patients with symptomatic heart failure and a left ventricular ejection fraction of ≤0.40, losartan compared to captopril improved survival with better tolerability. The objective of this study was to perform an economic evaluation of losartan versus captopril based on the results of the Losartan Heart Failure ELITE Study. The Losartan Heart Failure ELITE Study was a multinational, double-blind, randomized 48-week study comparing the safety and efficacy of losartan to captopril in angiotensin-converting enzyme-inhibitor-naive patients ≥65 years with symptomatic heart failure. Data on health care resource utilization were collected as part of the trial. We conducted a cost-effectiveness analysis to estimate the lifetime benefits of treatment and the associated costs. We observed no differences between treatments in the number of hospitalizations, hospital days, and emergency room visits per patient over the trial period. We estimated the total cost of losartan to be USD 54 (95% CI: USD –1,717, USD 1,755) less per patient than captopril over this time frame. We also estimated that over the projected remaining lifetime of the study population, losartan compared to captopril would increase survival by 0.20 years (undiscounted) at an average cost of USD 769 (discounted) more per patient. This cost increase translated into a cost-effectiveness ratio of USD 4,047 per year of life gained for losartan relative to captopril. In patients with symptomatic heart failure, losartan compared to captopril increased survival with better tolerability at a cost well within the range accepted as cost-effective.
Effect of Age, Heart Rate and Tricuspid Regurgitation on the Doppler Echocardiographic Evaluation of Right Ventricular Diastolic Function
Authors: Spencer Kirk T. , Weinert Lynn , Lang Roberto M.
Published: April 2003

Pulsed-wave Doppler analysis of tricuspid inflow and hepatic venous flow allows the determination of multiple parameters of right-ventricular (RV) diastolic function. This study sought to evaluate the influence of heart rate, age and tricuspid regurgitation on Doppler parameters of RV diastolic performance. We studied 80 subjects (20 normal and 60 with RV pathology) with Doppler recordings of the tricuspid inflow and hepatic vein. All tricuspid Doppler parameters were dependent on heart rate, age or regurgitation severity as were the hepatic vein S wave, S/D ratio and systolic filling fraction. The atrial reversal velocity in the hepatic vein Doppler tracing was not affected by age, heart rate or regurgitation. In addition, the inspiratory increase in this parameter was significantly elevated in RV pathologic states. This study demonstrates that most Doppler echocardiographic parameters of RV diastolic performance are dependent on age, tricuspid regurgitation or heart rate.