PubMed Health⌕ Search

Biomedical subjects

Charles J Bruce

Publications and source records attributed to Charles J Bruce.

18 recordsLinked to original sources
PubMed2006

Elevations of troponin in patients with epileptic seizures? What do they mean?

Cardiac troponin concentrations are important sensitive and specific markers for myocardial injury in clinical medicine. Troponin (TnT) elevations have been noted in some series in the setting of acute neurologic disease. We have previously reported that solitary seizures do not evoke elevations in TnT. The importance of this negative finding is exemplified by a patient who arrived at our clinic following a new onset seizure and in whom the cardiac TnT level was observed to rise. Triggered by this observation and by the knowledge that seizures alone would not do this, a subsequent targeted cardiologic workup documented what was believed to be an extension of a previously unrecognized myocardial infarction, with a seizure as its clinical presentation. Elevations of troponin should not be considered to be due to isolated seizures. This case illustrates the importance of having data concerning the response of troponin in various emergency and clinical situations.

Aged, 80 and over↗
PubMed2006

The effect of patient sex on recurrence of atrial fibrillation following successful direct current cardioversion.

BACKGROUND: The effect of patient sex on recurrence of atrial fibrillation after a successful direct current cardioversion is unknown. METHODS: This prospective study included 773 patients (486 [63%] men and 287 [37%] women) undergoing successful direct current cardioversion of atrial fibrillation between May 2000 and July 2003. Patient characteristics at presentation were recorded. The primary end point was the time between cardioversion and the first documented recurrence of arrhythmia. RESULTS: At presentation, women were older and had a higher prevalence of hypertension and valvular disease compared with men. In addition, women had worse mechanical left atrial appendage function. Arrhythmia recurrence was more prevalent in women (50.0% at 1 year compared with 43.4% in men, and 75.8% at 2 years compared with 67.0% in men; P = .03). On the basis of multivariate analysis, patient sex was a significant predictor of arrhythmia recurrence. There was no significant difference in overall mortality between men and women. CONCLUSIONS: Women were more likely than men to have recurrence of atrial fibrillation after successful direct current cardioversion. Patient sex should be taken into account with other clinical factors when making the decision about cardioversion for atrial fibrillation.

Aged↗
PubMed2005

Cortical afferents to the smooth-pursuit region of the macaque monkey's frontal eye field.

In primates, the frontal eye field (FEF) contains separate representations of saccadic and smooth-pursuit eye movements. The smooth-pursuit region (FEFsem) in macaque monkeys lies principally in the fundus and deep posterior wall of the arcuate sulcus, between the FEF saccade region (FEFsac) in the anterior wall and somatomotor areas on the posterior wall and convexity. In this study, cortical afferents to FEFsem were mapped by injecting retrograde tracers (WGA-HRP and fast blue) into electrophysiologically identified FEFsem sites in two monkeys. In the frontal lobe, labeled neurons were found mostly on the ipsilateral side in the (1) supplementary eye field region and lateral area F7; (2) area F2 along the superior limb of the arcuate sulcus; and (3) in the buried cortex of the arcuate sulcus extending along the superior and inferior limbs and including FEFsac and adjacent areas 8, 45, and PMv. Labeled cells were also found in the caudal periprincipal cortex (area 46) in one monkey. Labeled cells were found bilaterally in the frontal lobe in the deep posterior walls of the arcuate sulcus and postarcuate spurs and in cingulate motor areas 24 and 24c. In postcentral cortical areas all labeling was ipsilateral and there were two major foci of labeled cells: (1) the depths of the intraparietal sulcus including areas VIP, LIP, and PEa, and (2) the anterior wall and fundus of the superior temporal sulcus including areas PP and MST. Smaller numbers of labeled cells were found in superior temporal sulcal areas FST, MT, and STP, posterior cingulate area 23b, area 3a within the central sulcus, areas SII, RI, Tpt in the lateral sulcus, and parietal areas 7a, 7b, PEc, MIP, DP, and V3A. Many of these posterior afferent cortical areas code visual-motion (MT, MST, and FST) or visual-motion and vestibular (PP, VIP) signals, consistent with the responses of neurons in FEFsem and with the overall physiology and anatomy of the smooth-pursuit eye movement system.

Afferent Pathways↗
PubMed2005

Neural circuitry of judgment and decision mechanisms.

Tracing the neural circuitry of decision formation is a critical step in the understanding of higher cognitive function. To make a decision, the primate brain coordinates dynamic interactions between several cortical and subcortical areas that process sensory, cognitive, and reward information. In selecting the optimal behavioral response, decision mechanisms integrate the accumulating evidence with reward expectation and knowledge from prior experience, and deliberate about the choice that matches the expected outcome. Linkages between sensory input and behavioral output responsible for response selection are shown in the neural activity of structures from the prefrontal-basal ganglia-thalamo-cortical loop. The deliberation process can be best described in terms of sensitivity, selection bias, and activation threshold. Here, we show a systems neuroscience approach of the visual saccade decision circuit and the interaction between its components during decision formation.

Animals↗
PubMed2005

Residents can be trained to detect abdominal aortic aneurysms using personal ultrasound imagers: a pilot study.

Our objective was to test the hypothesis that internal medicine residents can be trained to screen for abdominal aortic aneurysm (AAA) using personal ultrasound imagers. We trained 5 randomly chosen internal medicine residents to image the abdominal aorta for patients with risk factors for AAAs using personal ultrasound imagers. Residents were trained in 3 or 4 one-on-one sessions with an instructor. To be eligible, patients had to be older than 65 years and have hypertension. After training, each of the 5 residents studied 3 patients independently. In 12 of the residents' 15 unsupervised studies, their abdominal aorta measurements were within 5 mm of the instructor's measurements with standard echocardiography (mean difference 3 mm, range 0-6 mm). Residents detected 3 previously unknown AAAs measuring 5.2, 4.2, and 3.9 cm in diameter. We conclude residents can be trained to image the abdominal aorta with personal ultrasound imagers and to identify AAAs in patients at risk.

Adult↗
PubMed2005

Prospective, randomized comparison of two biphasic waveforms for the efficacy and safety of transthoracic biphasic cardioversion of atrial fibrillation.

OBJECTIVES: The purpose of this study was to determine if there is a difference in commercially available biphasic waveforms. BACKGROUND: Although the superiority of biphasic over monophasic waveforms for external cardioversion of atrial fibrillation (AF) is established, the relative efficacy of available biphasic waveforms is less clear. METHODS: We compared the effectiveness of a biphasic truncated exponential (BTE) waveform and a biphasic rectilinear (BR) waveform for external cardioversion of AF. Patients (N = 188) with AF were randomized to receive transthoracic BR shocks (50, 75, 100, 120, 150, 200 J) or BTE shocks (50, 70, 100, 125, 150, 200, 300, 360 J). Shock strength was escalated until success or maximum energy dose was achieved. If maximum shock strength failed, patients received the maximum shock of the opposite waveform. Analysis included 141 patients (71 BR, 70 BTE; mean age 66.5 +/- 13.7. Forty-seven randomized patients were excluded because of flutter on precardioversion ECG upon blinded review (n = 25), presence of intracardiac thrombus (n = 7), or protocol deviation (n = 15). Groups were similar with regard to clinical and echocardiographic characteristics. RESULTS: The success rate was similar for the two waveforms (93% BR vs 97 BTE, P = .44), although cumulative selected and delivered energy was less in the BTE group. Only AF duration was significantly different between successful and unsuccessful patients. No significant complications occurred. CONCLUSIONS: Biphasic waveforms were very effective in transthoracic cardioversion of AF, and complication rates were low. No significant difference in efficacy was observed between BR and BTE waveforms. Impedance was not an important determinant of success for either biphasic waveform.

Aged↗
PubMed2004

Ultrasound strain imaging of altered myocardial stiffness: stunned versus infarcted reperfused myocardium.

BACKGROUND: In this study we evaluate the diastolic deformation of ischemic/reperfused myocardium and relate this deformation to tissue elastic properties. METHODS AND RESULTS: Farm pigs were subjected to left anterior descending coronary artery occlusion followed by reperfusion to create either stunning (n=12) or transmural myocardial infarction (n=12). Ultrasound-derived radial strain rates (SR) and strain were measured in the ischemic and remote walls. Myocardial stiffness was estimated from diastolic pressure-wall thickness relationship obtained from preload alterations. At reperfusion, end-systolic strain (epsilon(sys)) was significantly reduced in both stunned and infarcted walls compared with their remote walls (3+/-3% versus 26+/-2% and 1+/-0% versus 33+/-5%, respectively; P<0.0001) or baseline values. Diastolic passive deformation (epsilon(A)) and rates of deformation during early (E(SR)) and late (A(SR)) diastole were comparable between stunned and remote walls (epsilon(A): 7.3+/-1.6% versus 7.9+/-1.9%; E(SR): -2.7+/-0.4 s(-1) versus -2.6+/-0.5 s(-1); A(SR): -1.8+/-0.2 s(-1) versus -1.9+/-0.3 s(-1); P=NS for all) but were of significantly lower magnitude in infarcted walls versus remote walls (epsilon(A): 1.1+/-0.2% versus 11.4+/-1.9%; E(SR): -0.3+/-0.1 s(-1) versus -2.4+/-0.4 s(-1); A(SR): -0.3+/-0.1 s(-1) versus -2.5+/-0.4 s(-1); P<0.0001 for all). Stiffness coefficient of exponential diastolic pressure-wall thickness relation was higher for infarcted (P<0.05) but not for stunned walls (P=NS) compared with their remote walls. CONCLUSIONS: Early after postischemic reperfusion and in the presence of severely reduced systolic deformation, diastolic passive deformation (and rates of deformation) can distinguish stiff, noncompliant, transmurally infarcted myocardial walls from those more compliant walls containing viable but stunned myocardium.

Animals↗
PubMed2004

Distinctive changes in end-diastolic wall thickness and postsystolic thickening in viable and infarcted myocardium.

OBJECTIVES: In this study, we sought to compare the magnitude of changes in end-diastolic wall thickness (WT(ed)) and postsystolic thickening (PST) in a swine model of stunning and reperfused acute myocardial infarction, and to explore the relationship between WT(ed) and PST. METHODS: Twenty-six pigs were subjected to left anterior descending coronary artery occlusion followed by reperfusion to induce stunning (n = 6), nontransmural (n = 8), or transmural (n = 12) myocardial infarction. Myocardial wall thickness was measured using intracardiac echocardiography. Transmural extent of necrosis (TEN) was quantified by triphenyltetrazolium chloride technique. RESULTS: During the first minutes of reperfusion, a marked increase in WT(ed) occurred in the myocardial walls with nontransmural and transmural infarct (42% and 102%, respectively) but less in those with stunning (19%). PST persisted at reperfusion in walls with stunning and nontransmural infarct (23% and 26%, respectively). In transmurally infarcted walls, PST progressively decreased either during occlusion (5/12 pigs) or shortly after reperfusion (7/12 pigs). PST at reperfusion was virtually absent when TEN was >70%. Both PST and the increase in WT(ed) at reperfusion correlated well with TEN (P <.0001 for both). Changes in PST at reperfusion were weakly correlated with changes in WT(ed). CONCLUSIONS: A marked increase in WT(ed) after reperfusion and absence of PST indicate transmural myocardial infarction. Presence of PST at reperfusion indicates viable tissue in more than 30% of wall thickness. The results suggest that amplitude of PST is modulated predominantely by factors related to the severity of ischemia and, to a smaller extent, by changes in wall thickness.

Analysis of Variance↗
PubMed2004

Intracardiac echocardiographic guidance during transcatheter device closure of atrial septal defect and patent foramen ovale.

OBJECTIVES: To describe our experience with intracardiac echocardiographic (ICE) guidance during transcatheter device closure of atrial septal defect (ASD) and patent foramen ovale (PFO) and to describe a detailed stepwise approach for performing ICE examinations. PATIENTS AND METHODS: We reviewed the ICE results of all patients who underwent transcatheter device closure of ASD/PFO at the Mayo Clinic in Rochester, Minn, between October 2000 and November 2002. Conscious sedation was used, and all ICE studies were performed using a diagnostic ultrasound catheter. RESULTS: Ninety-four patients (47 male; median age, 51 years [range, 17-81 years]) underwent ICE during transcatheter device closure of ASD/PFO. Total procedure time was 128 minutes (range, 27-320 minutes). ICE identified a previously unrecognized anatomical diagnosis in 32 of 94 patients. An additional ASD or PFO was found in 16 patients; a redundant atrial septum or an atrial septal aneurysm was found in 12 patients. There were few ICE complications (4%): 3 patients developed atrial fibrillation, and 1 developed supraventricular tachycardia; of these 4, 2 resolved spontaneously, and 2 required cardioversion with no recurrence. CONCLUSION: ICE provides anatomical detail of ASD/PFO and cardiac structures facilitating congenital cardiac interventional procedures. ICE eliminates major drawbacks related to the use of transesophageal echocardiographic guidance for transcatheter device closure of ASD/PFO, specifically problems related to airway management. Finally, ICE gives the interventional cardiologist the ability to control all aspects of imaging without relying on additional echocardiographic support. We believe that ICE should be considered the preferred imaging technique for guidance of transcatheter device closure of ASD/PFO in adults and larger pediatric patients.

Adolescent↗
PubMed2003

Hand-carried ultrasound-guided pericardiocentesis and thoracentesis.

To date, ultrasound-guided centeses have required the use of large, diagnostic ultrasound equipment that can be cumbersome and not readily available. In this study, we sought to evaluate the use of portable, hand-carried ultrasound devices in guidance of pericardiocentesis and thoracentesis. Hand-carried ultrasound was used to define location of the maximal extent of the effusion and its proximity to the skin surface, confirm needle entry and site, and to evaluate postprocedural result. A total of 12 patients who were stable and hospitalized were prospectively enrolled, 9 for pericardiocentesis and 3 for thoracentesis. We concluded that under the direction of a suitably trained physician, hand-carried ultrasound provided images suitable for guidance of a pericardiocentesis or thoracentesis preprocedurally, intraprocedurally, and postprocedurally.

Adolescent↗
PubMed2002

Intracardiac phased-array imaging: methods and initial clinical experience with high resolution, under blood visualization: initial experience with intracardiac phased-array ultrasound.

OBJECTIVES: This study was designed to test the feasibility of high-resolution phased-array intracardiac imaging. BACKGROUND: Intracardiac echocardiographic imaging of the heart during interventional electrophysiologic (EP) procedures has been limited by inadequate ultrasound penetration and absence of Doppler hemodynamic and flow information produced by rotating mechanical ultrasound elements. METHODS: A 10F (3.2 mm) phased-array, variable 5.5 to 10 MHz frequency imaging catheter with a four-way deflectable tip was applied in 24 patients undergoing EP studies. Sixteen prespecified cardiac targets were imaged from a right heart venue. RESULTS: Fifteen patients had no underlying organic heart disease; nine had ischemic, cardiomyopathic, valvular or congenital heart disorders. Longitudinal and short-axis imaging readily disclosed each cardiac valve, support structures and chamber, as well as the pericardium, right and left atrial appendages, the junction of the right atrium and superior vena cava, crista terminalis, tricuspid valve isthmus, coronary sinus orifice, membranous fossa ovalis and pulmonary veins. The average target depth was 8.8+/-1.5 cm (range 0.5 to 15 cm), with adequate penetration at a 7.5 MHz imaging frequency. Color flow and Doppler utilities clearly characterized transaortic and pulmonic valve and pulmonary vein blood flow, including during low output states. CONCLUSIONS: These first human studies with this technology demonstrate the methods, feasibility and utility of intracardiac phased-array vector and Doppler imaging for long-axis, apex-to-base global cardiac imaging. High resolution of endocardial structures and catheters suggests additional utility for visualizing interventional procedures from the right heart.

Arrhythmias, Cardiac↗
PubMed2002

Miniaturized transesophageal echocardiography in newborn infants.

BACKGROUND AND METHODS: A miniaturized 5.5 to 10 MHz, phased-array, single longitudinal plane transducer mounted on a 3.3-mm diameter catheter (miniaturized transesophageal echocardiography [TEE]) may overcome mechanical limitations of standard pediatric transesophageal probes. We evaluated whether the miniaturized TEE probe could define clinically relevant anatomy in 17 infants who weighed less than 6 kg. RESULTS: Twenty-two studies were performed in 17 infants without complication, weighing 2.1 to 5.6 kg. Twenty of twenty-two studies were diagnostic. Pediatric biplane TEE was not possible in 13 studies. Lack of horizontal plane imaging with miniaturized TEE made evaluation difficult in patients with atrioventricular septal defect. CONCLUSION: Miniaturized TEE provided diagnostic intraoperative TEE in the majority of infants studied and may allow broader and safer application of TEE to neonates and small infants.

Cardiac Surgical Procedures↗
PubMed2002

Characterization of reperfused infarcted myocardium from high-frequency intracardiac ultrasound imaging using homodyned K distribution.

Myocardial changes caused by infarction/reperfusion (contraction band necrosis, hemorrhage, edema, etc.) may result in an increased scatterer density and a variation in scatterer arrangement. This paper, for the first time, models most of the scattering conditions resulting from the interaction of ultrasound and normal/reperfused infarcted myocardium using the homodyned K distribution. Furthermore, this method is used to characterize the change in scatterer density by calculating the effective scatterer number per resolution cell. The reliability and the effects of attenuation and scan conversion on effective scatterer number estimation are discussed. We used in vivo data acquired using high-frequency intracardiac ultrasound imaging (8.5 MHz) from the left and right ventricles of open-chest pigs in an acute infarction/reperfusion model. The results show that the homodyned K distribution describes the statistical distribution of backscattered signal from both normal and abnormal myocardium. A significant increase in scatterer density occurs in the infarcted region after reperfusion compared with the same region at baseline (normal myocardium prior to occlusion). The scatterer density of the normal region does not change significantly after reperfusion. We conclude that the homodyned K distribution may characterize normal and reperfused infarcted myocardium using high-frequency intracardiac ultrasound images.

Animals↗
PubMedDate not supplied

3D visualization, analysis, and treatment of the prostate using trans-urethral ultrasound.

In the year 2000, it is estimated that over 20,000 men underwent transperineal interstitial permanent prostate brachytherapy (TIPPB) for treatment of prostate cancer. Trans-urethral ultrasound (TUUS) is a new interactive, real-time 3D imaging method that may be effective in therapy-guidance during and after TIPPB. TUUS provides higher resolution than trans-rectal ultrasound (TRUS). TUUS can be used to accurately localize radioactive seeds and therefore contribute to more accurate determination of radiation dose distribution throughout the tissue after the completion of the procedure, similar to information currently provided by expensive and offline CT scans. A TUUS catheter can be used to acquire 2D section images or 3D volume images for detailed analyses of the prostate and associated tissue. Initial development of TUUS imaging was carried out on an ultrasound-equivalent prostate phantom with cylindrical dummy radiation sources. This was followed by preliminary studies in animals and then in patients. Both CT and TRUS data were acquired in these studies for comparative purposes. Segmentation of the prostate capsule and radioactive seeds was carried out using several semi-automated 3D algorithms and image processing techniques. Presentation of the data to the clinician is provided by a variety of complementary 2D and 3D display methods. In comparison with the CT data, TUUS data provided both greater spatial resolution and better soft tissue differentiation. In comparison to the TRUS data, TUUS data provided greater resolution and better seed localization. Combining these advantages suggests the possibility of TUUS becoming the exclusive imaging method in prostate cancer brachytherapy.

Humans↗