Myocardial metabolism in open-heart surgery using whole blood in the pump-oxygenator.
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Acid-Base Equilibrium↗
Biomedical subjects
R D White
Publications and source records attributed to R D White.
Significance of the S1S2S3 electrocardiographic pattern in children.
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Adolescent↗
Defibrillator failures. Causes of problems and recommendations for improvement. Defibrillator Working Group.
The Defibrillator Working Group of the Food and Drug Administration reviewed data from the Medical Device Reporting System and a recent five-state survey, as well as information presented at two Food and Drug Administration-sponsored conferences. These data include 156 reports of defibrillator problems to the Emergency Care Research Institute Problem Reporting Network, 495 reports of device problems to the Medical Device Reporting System, 676 reports of "defibrillator failure" in the five-state survey, 594 inspections of in-service defibrillators, and site visits to 212 emergency care facilities. The Defibrillator Working Group concluded that the frequency of defibrillator failures during clinical use may be unacceptably high. While some failures are attributable to component malfunctions, evidence suggests that errors in operator use and errors in defibrillator care and maintenance account for a high proportion of defibrillator failures. Inadequate initial training and cursory continuing education increases the chances of operator errors at the moment when correct operation is needed most. Failure of operators to perform daily equipment checks leads to poor familiarity with the equipment and failure to identify component failures or damaged devices. Many defibrillators and batteries are kept in service beyond an expected useful life, given their level of clinical use. In smaller hospitals and emergency medical services systems periodic maintenance responsibilities are not always appropriately delegated between qualified engineering personnel and defibrillator operators, and some systems completely lack services from clinical engineers. The objectives of the Defibrillator Working Group are to make personnel who use defibrillators more aware of the potential for errors in operator performance and in periodic maintenance and to recommend improvements in training, maintenance, and defibrillator design. This article presents the initial observations and recommendations of the working group.
Education, Continuing↗
Electrocardiograph-independent, "wireless" cardiovascular cine MR imaging.
A new electrocardiograph (ECG)-independent, "wireless" gating technique for cine magnetic resonance (MR) imaging was evaluated in 23 cases of cardiovascular disease; in each case, standard ECG-dependent image loops were available for comparison. The ECG-independent strategy references cine MR imaging data retrospectively to inherent periodic changes in MR signal related to the cardiac cycle. With a "double-section" method, both timing data reflecting such changes and imaging data can be acquired simultaneously. "Artificial R waves" are extracted from the timing data acquired with a projection approach. The ECG-independent image loops were diagnostic in 91% of cases. Their overall image quality was at least equal to that of available ECG-dependent versions in only 39% of cases, but this proportion increased to 53% if cases with suboptimal imaging orientations for monitoring of the motion-dependent signal changes were excluded. Orientation appeared to be the primary technical limitation associated with this ECG-independent technique; however, poor ventricular function also significantly impaired performance. Improvement in the performance of the ECG-independent strategy is anticipated with technical advances.
Adolescent↗
Cardiovascular MR imaging: current level of clinical activity.
Relative to other clinical magnetic resonance (MR) imaging activities, cardiovascular (CV) MR imaging has been slow to demonstrate a clinical presence. To better understand the present situation in clinical CV MR imaging, a survey of Society for Magnetic Resonance Imaging (SMRI) members was conducted. A large majority (78%) of the 90 sites responding to the survey reported clinical activity in CV MR imaging. Of these 70 sites, 46% restricted such activity to routine clinical work, while 3% restricted it to clinical research. The remaining 51% conducted both. At all clinical sites, the overall frequency of performance of clinical CV MR imaging was variable (mean, 4.2 and 13.8 cases per month at routine-only and combined routine-research sites, respectively). In clinical CV studies, gated static, multi-level spin-echo and dynamic gradient-echo (cine) techniques were most common. At the 68 sites involved in routine clinical CV MR imaging, primarily anatomic studies composed a much higher proportion of the total (mean, 86%) than primarily functional studies. The evaluation of acquired thoracic aortic disease, congenital cardiac malformation, and para- or intracardiac mass were the most prevalent anatomic indications overall. Approximately half of the same sites assessed functional aspects of CV disease. The assessment of ventricular dysfunction and valvular dysfunction were the most common functional objectives. The survey indicated that the level of clinical activities in CV MR imaging was low and that most responding sites were involved in clinical CV MR imaging primarily for detection and delineation of anatomic abnormalities.
Cardiovascular Diseases↗
Validation of cine phase-contrast MR imaging for motion analysis.
The accuracy of cine phase-contrast magnetic resonance (MR) imaging for motion analysis was evaluated. By using a rotating phantom and postprocessing algorithm for phase tracking, errors arising during data acquisition were identified and compensation methods were developed. A spatially varying background phase offset in the velocity images was found to be due to eddy current-induced fields. The magnitude of the offset was in the range of 0-20 cm/sec, which is of the same order of magnitude as cardiac contractile velocities. Background offset is thus an important source of error in tracking cardiac motion. Study of different tracking algorithms revealed the need for an integration scheme using motion terms higher than velocity. Also, considerable improvement in the accuracy and stability of the predicted trajectories was obtained by averaging the trajectories proceeding both forward and backward in time from the starting point. With the algorithm developed, the motion of the phantom was tracked through a complete rotation of the phantom to an accuracy of 2 pixels.
Algorithms↗
Retrospective cardiac gating: a review of technical aspects and future directions.
The advent of short TR gradient-echo imaging has made it possible to acquire cine images of the heart with conventional whole body MRI scanners. In this paper, technical details of the data collection and image reconstruction process for cine MRI using retrospective cardiac gating are presented. Specifically, the following issues are discussed: data sorting and interpolation; time resolution; motion compensation and phase information; the type of steady state sequence including optimal flip angle; respiratory motion and correction; and the potential of 3D imaging.
Electrocardiography↗
Left ventricular volume calculation with integrated backscatter from echocardiography.
Integrated backscatter analysis (IB) is a new echocardiographic method for automatically differentiating tissue from blood on the basis of differences in the amplitude of reflected ultrasound. Left ventricular volume was estimated with IB by use of a modification of Pappus' theorem and a summated ellipsoid method. IB measurements correlated well with a standard biplane area-length method derived off-line from endocardial borders drawn by hand from the same echocardiographic data (y = 1.09 x - 35, r = 0.95). Integrated backscatter measurement of ventricular volume derived from six imaging planes with both the Pappus' rule and the summated ellipsoid methods correlated well with magnetic resonance imaging volume estimates (r = 0.91 and r = 0.90, respectively), whereas use of one imaging plane correlated less well (r = 0.75). Automated analysis of integrated backscatter differentiates tissue from blood sufficiently to allow accurate volume calculations compared with magnetic resonance imaging and to standard hand-drawn echo techniques. This method provides accurate measurement of left ventricular volumes that should be useful in clinical hemodynamic assessments.
Adolescent↗
Biphasic truncated exponential waveform defibrillation.
This paper presents data from studies that have compared the efficacies of biphasic truncated exponential (BTE) and monophasic damped sine (MDS) waveform defibrillation in patients with out-of-hospital cardiac arrest and in in-hospital defibrillation. When a shock is delivered, rhythms evolve rapidly in a variety of directions and take different courses, even over a short time. When defibrillation is defined as termination of ventricular fibrillation at 5 seconds postshock, whether to an organized rhythm or asystole, low-energy BTE shocks appear to be more effective than high-energy MDS shocks in out-of-hospital arrest. For future research, the terms associated with defibrillation should be standardized and used uniformly by all investi-gators. In particular, there should be an agreed-upon definition of shock efficacy.
Adolescent↗
Effects of microsomal enzyme induction on the toxicity of pyrrolizidine (Senecio) alkaloids.
Effects of microsomal enzyme induction by phenobarbital (PB) injection (ip) and ingestion of Eucalyptus globulus foliage or phenothiazine (PT) on the toxicity of pyrrolizidine alkaloids (PA) or dried plant material of Senecio longilobus (SL) and Senecio jacobaea (SJ) were evaluated in rats. The oral median lethal doses (LD50) for a PA mixture extracted from SL at 72, 144, and 168 h post PA administration were approximately greater than 320, 190, and 160 mg/kg, respectively. Induction of mixed-function oxidase (MFO) activity by PB or dietary eucalyptus leaves resulted in only a marginal effect on the acute LD50, with no effective change at 168 h. The LD50 values at 72, 144, and 168 h for PB-treated rats were approximately 320, 190, and 160 mg/kg, and for eucalyptus treated rats approximately 127, 133, and 133 mg/kg, respectively. Dietary PT did not alter the toxicity of SJ but did cause reductions in feed intake and average daily gain. Supplemental cysteine increased (p less than 0.05) survival time in SJ-consuming rats, with a concomitant increase (p less than 0.05) in SJ ingestion, and caused slight increases in average daily gain. The simultaneous addition of cysteine and PT to an SJ-containing diet resulted in an increased (p less than 0.05) survival time over SJ and SJ + PT diet groups and a slight decrease in survival time compared to the SJ + cysteine group.
Animals↗
Brief report: birth status, medical complications, and social environment: individual differences in development of preterm, very low birth weight infants.
OBJECTIVE: To assess whether medical complications mediate the relationship between birth status (i.e., birth weight and gestational age) and developmental outcome of preterm, very low birth weight (VLBW) infants, as well as the role of the early social environment (maternal distress and social support) in infant development. METHOD: Birth status and medical complication information was collected during the child's NICU stay. Maternal distress was assessed with the Beck Depression Inventory and the Parenting Stress Index at 4 months corrected infant age. Social support was measured with the Dunst Scales at 4 months corrected age. Child development measures were collected at 4 and 13 months corrected age (Bayley MDI and PDI), and at 36 months chronological age (PPVT-R and Achenbach CBCL). RESULTS: Medical complications mediated the birth status-outcome relationship at 4 and 13 months, but not at 36 months. The 36-month outcomes were predicted by 4-month maternal distress and social support. CONCLUSIONS: Prematurity and VLBW are indirectly related to early developmental outcome through their association with medical complications. However, by 36 months, developmental outcomes are more closely related to aspects of the early social environment than to early physiological factors.
Adult↗
Bioimpedance monitoring: better than chest x-ray for predicting abnormal pulmonary fluid?
Bioimpedance monitoring may aid in treating heart failure. Mean thoracic electrical impedance (Zo) is inversely proportional to thoracic fluid volume and may offer greater sensitivity for detecting thoracic fluid. OBJECTIVE. Compare bioimpedance monitoring thoracic fluid detection to that of chest x-ray. METHOD. Prospective convenience sample. SETTING. 1000 bed teaching hospital. PARTICIPANTS. Patients with suspected heart failure and shortness of breath. A single blinded radiologist interpreted chest x-rays as: normal, cardiomegaly, or abnormal pulmonary fluid. STATISTICS. General linear model with post hoc Bon Ferroni pairwise comparisons. RESULTS. 131 patients, mean age 66.8 years, 64.3% male, with an initial mean Zo=18 ohms. There was a significant difference (p<0.0002) between patients with cardiomegaly (Zo=17.5+/-5.5) or abnormal pulmonary fluid on chest x-ray (Zo=17.2+/-4.2) compared to normals (Zo=23.4+/-5.4). There was no difference between cardiomegaly and abnormal pulmonary fluid patients. CONCLUSION. Bioimpedance measurement may detect pulmonary fluid not apparent on chest radiograph. (c)2000 by CHF, Inc.
Journal Article↗
Malignant tumors of the heart and great vessels: MR imaging appearance.
Fortunately, primary tumors of the heart and great vessels are rare. These primary tumors include angiosarcoma, malignant fibrous histiocytoma, high-grade and pleomorphic sarcoma, and paraganglioma with pericardial and myocardial invasion. Symptoms are often nonspecific and include chest pain and dyspnea. Although these tumors are often diagnosed with echocardiography and computed tomography, magnetic resonance (MR) imaging currently appears to be the imaging modality of choice because of its diverse capabilities, which include multiplanar imaging for excellent anatomic definition of the heart, pericardium, mediastinum, and lungs; improved morphologic differentiation between tumor tissue and surrounding cardiovascular, mediastinal, or pulmonary tissues; dynamic imaging with a gated cine-loop acquisition; and assessment of tissue perfusion. The use of gadopentetate dimeglumine is helpful in achieving tumor enhancement on MR images but is not required. MR imaging is also useful in assessing tumor response to surgery, radiation therapy, and chemotherapy.
Adult↗
MR angiography of the thoracic aorta with an electrocardiographically triggered breath-hold contrast-enhanced sequence.
An electrocardiographically (ECG) triggered breath-hold contrast material-enhanced magnetic resonance (MR) angiography sequence has been developed for imaging the thoracic aorta. A three-dimensional (3D) gradient-echo sequence is used with a contrast material bolus. Forty-nine patients with various aortic abnormalities and five healthy volunteers underwent imaging with the sequence. All studies were performed in a single breath hold. ECG-triggered breath-hold contrast-enhanced MR angiography was tolerated in 48 of the 49 patients. The images demonstrated no respiratory motion artifacts and diminished pulsation artifacts. The cardiac chambers, aortic root, ascending and descending aorta, aortic arch, proximal arch vessels, and proximal coronary arteries were clearly demonstrated and not obscured by ghost artifacts. The 3D data set allowed excellent multiplanar reformation, permitting orthogonal or oblique views of the vascular anatomy. A variety of congenital and acquired abnormalities were clearly identified. When this sequence is used, it is important to evaluate both the maximum-intensity projection and source images. Delayed imaging should be performed to detect late filling. In conjunction with cine MR and T1-weighted spin-echo imaging, ECG-triggered breath-hold contrast-enhanced MR angiography should be considered the technique of choice for imaging the thoracic aorta.
Aorta, Thoracic↗
Histologic lesions associated with intravenous infusions of large volumes of isotonic saline solution in rats for 30 days.
The objective of this study was to characterize the changes associated with intravenous infusions of large volumes of isotonic saline solution in rats so that effects of the infusion process could be more easily distinguished from effects of test articles. Male Sprague-Dawley rats weighing approximately 225-275 g at the beginning of the study were given intravenous infusions of isotonic saline solution once daily for 30 consecutive days at dosages of 40 or 80 ml/kg body weight. Saline solution was administered through catheters placed in the caudal veins of the tail according to one of the following regimens: 80 ml/kg at 0.25 ml/min; 80 ml/kg at 0.5 ml/min; 80 ml/kg at 1.0 ml/min; and 40 ml/kg at 1.0 ml/min. Control rats were catheterized but not administered intravenous fluids. One day following the last treatment, all rats were necropsied and major organs were collected in 10% formalin. Histologic lesions associated with treatment included increased incidence and severity of pulmonary periarterial infiltrates of eosinophils, multifocal pulmonary inflammation, pulmonary granulomas that often contained hairshaft fragments, endothelial hypertrophy and hyperplasia within pulmonary arterial vessels, and pulmonary arterial medial thickening. Infiltrates of eosinophils around small pulmonary arteries were more severe in rats given intravenous infusions than in untreated rats and were more severe in rats given isotonic saline at the 80-ml/kg dosage than at the 40-ml/kg dosage. The severity of periarterial infiltrates of eosinophils increased with increasing infusion rates in rats that received 80 ml/kg isotonic saline. Pulmonary granulomas and multifocal pulmonary inflammation were observed in more rats that received intravenous saline than in control rats, but their incidences did not appear to vary with the volume or rate of infusion. Multifocal endothelial hypertrophy and hyperplasia occurred in most rats given isotonic saline solution at all volumes and rates, but not in untreated control rats. Inflammatory lesions in the tail near the injection site were considered sequellae of catheter insertion that, in some instances, may have been exacerbated by intravenous saline infusion. There were no lesions in other organs that were attributable to intravenous infusions of isotonic saline solution.
Animals↗
Drugs in cardiac supportive care.
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Arrhythmias, Cardiac↗
Lung and heart-lung transplantation: the state of the art.
Lung and heart-lung transplantation is one of the most rapidly evolving transplantation fields. Survival has been improving with better patient selection, better graft preservation, and better immunosuppression. This paper outlines criteria for patient selection, reviews the surgical options involving lung transplantation, and discusses factors influencing morbidity and survival in these patients. The Cleveland Clinic Foundation experience with these procedures is presented. Lung and heart-lung transplantation has emerged from the experimental realm to the therapeutic, and can now be offered as an effective treatment option to many patients with previously fatal heart and lung disorders.
Contraindications↗
The Maze procedure: surgical therapy for refractory atrial fibrillation.
Although atrial fibrillation is well tolerated by most patients, in some patients the consequences may be severe. The Maze procedure is a new open-heart operation that creates a carefully designed maze of incisions in the atrial myocardium; this maze then acts as an electrical conduit to channel atrial impulses from the sinoatrial node to the atrioventricular node. The Maze procedure has been shown to restore sinus rhythm and atrial systole (thus reducing the risk of thromboembolism), improve hemodynamics, alleviate palpitations, and eliminate the need for antiarrhythmic and anticoagulant drugs. We describe our first patient to undergo this operation.
Aged↗