Ethnic variations in lung cancer.

Cancer of the lung is the most frequent cancer in the world, but with wide geographical variation in risk. It is most spread among males of all races worldwide, the only exception being its incidence among Chinese women aged 70 years and older. When comparing the different ethnic groups we have to consider that besides inhaling cigarette smoke actively or as a passive smoker the exposure to occupational carcinogens varies considerably according to different work places. In our study we compared 10 years of data from African-Americans in Howard University Hospital, Washington D.C. with 20 years of data from the white population in the University Hospital of Vienna, Austria. Ethnic patterns are generally consistent within each group in terms of both incidence and mortality. The difference in susceptibility between the sexes, the three major racial groups and already proven differences in genetic variations indicate the difference between individuals concerning the initiation and progression of lung cancer.

Value of three-dimensional echocardiography as an adjunct to conventional transesophageal echocardiography.

Three-dimensional imaging of cardiac structures could enhance the functional understanding and the interpretation of pathologies. Limited processing capabilities, relocation problems and inadequate two-dimensional image quality have previously limited its applicability. Recently, an integrated echocardiographic computerized tomography unit (echo-CT) which uses a transesophageal approach has been developed. This system is capable of sampling and processing multiple echocardiographic images and, thus, provides three-dimensional views. To evaluate the feasibility and potential of this technique, we studied 69 patients with various cardiac disorders. All but 3 patients (96%) tolerated the procedure well allowing at least one scan to be performed. No complications were encountered. The indication for echo-CT included coronary artery disease (n = 4), mitral valve disease (n = 18), suspected arterial embolism (n = 19), masses (n = 8), congenital malformation (n = 10), postcardiac surgery (n = 8), aortic aneurysm (n = 1) and suspected left-to-right shunt (n = 1). Conventional transesophageal echocardiography revealed a pathology in 45 patients. Of these pathologies, 37 (82%) could be reconstructed and displayed in three-dimensional views. Three-dimensional imaging provided an improved spatial understanding of the pathology in 21 cases (39%). Echo-CT was especially valuable in diseases of the mitral value (i.e. mitral valve prolapse, flail leaflets, mitral stenosis) where it had the potential to delineate the location, type and morphology of defects. In conclusion, three-dimensional transesophageal imaging enhances image interpretation and understanding. This could be of value in complex morphologies and cardiac disorders in which surgical repair is attempted.

Three-dimensional echocardiography using a transoesophageal imaging probe. Potentials and technical considerations.

Appreciation of three-dimensional relationships could be useful in cardiac diagnosis, decision making and planning of surgery. However, current ultrasound techniques provide only two-dimensional views. A recently developed echocardiographic computerized tomography unit allows reconstruction of three-dimensional images from a series of transoesophageal slices. To evaluate the potentials and limitations of this technique we performed echo computer tomographic examinations in 104 patients with a total number of 227 scans. All but two patients tolerated the procedure well and no serious complications were encountered. Indications for echo computer tomography included coronary artery disease, valvular heart disease, atrial masses, myocardial infarction, mitral and aortic valve replacement, aortic aneurysm and congenital defects. Most of the anatomical structures could be visualized with the best results obtained for the left atrium, the left ventricular outflow tract and the aortic and mitral valve apparatus. However, a variety of technical factors must be considered to achieve optimal results and to avoid misinterpretation. In 86% of patients the underlying pathology could be visualised by echo-computed tomography, particularly congenital defects such as those of the atrial or ventricular septa, but mitral valve pathologies provided the best results. In these cases three-dimensional imaging led to a better perception and understanding of structural relationships. In conclusion, despite current limitations in data acquisition, processing and computing power, echo computer tomography has the potential to provide relevant information in selected clinical settings.

A beat-by-beat analysis of electrocardiograms from cardiac transplant recipients.

A software system is described for producing a beat-by-beat analysis of the electrocardiograms from patients after heart transplantation. Pacemaker spikes are automatically detected and eliminated from the signals. R waves are located by a robust and accurate two-step algorithm. Based on the variable length of single heart beats, the Fourier coefficients of three orthogonal surface leads and of two intracardiac leads are calculated beat-by-beat. Power spectra are then obtained by combining contributions from the variable fundamental frequency and its multiples (harmonics) into fixed frequency classes of 1 Hz width and averaging over 60-120 cardiac cycles. Additionally, averaged beat-by-beat power spectra are calculated for windowed QRS complexes and T waves. As by-products, single beat quantities, such as R-R and R-T intervals, averaged signals for all leads, and the orientational autocorrelation function of the electrical vector of the heart, are obtained. Following beat-by-beat evaluation, mean values and standard deviations are obtained for all quantities.