Part 2: GENERAL EVALUATION OF THE PATIENT Chapter 12:
On November 8, 1895, Wilhelm Conrad Roentgen discovered x-rays1 and ushered in a new era of diagnostic roentgenology. With wavelengths only 1/10,000 those of visible light, x-rays can penetrate the human body to produce roentgenograms, which revolutionized the field of medical diagnosis. Chest roentgenography in particular has since become a routine part of medical workup because of the invaluable information it can provide.
Familiarity with the altered anatomy and understanding of the underlying pathophysiology of a diseased heart are the cornerstones to appropriate interpretation of its roentgen manifestations. The conventional four-view cardiac series is tabulated in Table 12-1 and the views are illustrated in Fig. 12-1CB*;H;
Table 12-1: Conventional Four-View Cardiac Series
Posteroanterior (PA) view With barium
Left lateral (lateral) view With barium
45° Right anterior oblique (RAO) view With barium
60° Left anterior oblique (LAO) view Without barium
The approach to the chest roentgenogram should be thorough and objective so that no clue is overlooked and no bias is incorporated in the process of radiographic analysis.2^ Rib notching (see Fig. 12-1A -H ; B), for example, offers important clues to the diagnosis of coarctation of the aorta.4,6 To prevent occasional erroneous clinical information from misleading the radiographic interpretation, films should at first be read without any knowledge about the patient. A patient may be referred, for instance, because of "bronchial asthma" refractory to therapy, only to be found later to suffer from cardiac asthma due to critical mitral stenosis. In this case, the classic radiographic manifestations of severe mitral stenosis should help clarify the confusion and prompt a change in patient management.
On other occasions, a secundum atrial septal defect may be misinterpreted as mitral stenosis because of similar physical signs. The split second sound may be misinterpreted as the opening snap. The diastolic rumble due to increased flow through a normal tricuspid valve may mimic the diastolic murmur of mitral stenosis. The x-ray signs of the two entities, however, are quite different Fig. 12-2.8 versus
The final radiologic conclusion, however, should be drawn only after correlating the x-ray findings with clinical information and other laboratory parameters.
The radiologic examination for heart disease consists of six major steps. They are (1) roentgenographic examination for anatomy; (2) fluoroscopic examination for dynamics, (3) comparison, (4) statistical guidance, (5) clinical correlation, and (6) conclusion (Table 12-2).
Table 12-2: Major Steps of Roentgenologic Examination
Roentgenographs examination for anatomy Overview, e.g., rib notching
Pulmonary vascularity, e.g., shunt vascularity in ASD Lung parenchyma, e.g., ossification in critical MS Cardiac size, e.g., huge right heart in Ebstein's anomaly Cardiac contour, e.g., boot-shaped heart in TOF Abnormal densities, e.g., calcification of LV aneurysm Abnormal lucency, e.g., conspicuous fat stripes in PE Cardiac malpositions, e.g., dextrocardia with SS Other abnormalities, e.g., Holt-Oram syndrome Fluroscopic observation for dynamics Comparison Statistical guidance Clincal correlation Conclusion
Abbreviations: ASD = atrial septal defect; MS = mitral stenosis; TOF = tetralogy of Fallot; LV = left ventricle; PE = pericardial effusion; SS = situs solitus.
ROENTGENOGRAPHIC EXAMINATION FOR ANATOMY An Overview
The first step is to survey the roentgenogram and assess the entire situation, searching particularly for noncardiac conditions that may reflect heart disease. For instance, a right-sided stomach with an absent image of the inferior vena cava may suggest the possibility of congenital interruption of the inferior vena cava with azygos continuation7,8 (Fig. 12-4). A narrowed anteroposterior diameter of the thorax may be the cause of an innocent murmur^ Fig. 12-5).
Figure 12-4: Patient with situs ambiguous, interruption of the inferior vena cava, ventricular septal defect, and polysplenia. A. Posteroanterior view shows that the aortic arch and the heart are left-sided and the stomach (lower arrows) is right-sided. The azygos vein (upper arrow) is markedly enlarged. The heart is mildly enlarged, and there is a moderate increase in pulmonary vascularity. B. Lateral view shows an absent image of the inferior vena cava. The azygos arch (arrow) is markedly dilated.
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