A. Santolicandro

Factors affecting regional pulmonary blood flow in left heart valvular disease

Abstract The base to apex distribution of blood flow per unit of lung volume was assessed by pulmonary scintigraphy in 99 patients with rheumatic heart disease. The prevalent valvular lesion was mitral stenosis in 56, mitral regurgitation in 14, aortic stenosis in 11 and aortic insufficiency in 18. Each patient underwent hemodynamic assessment by cardiac catheterization within a few days of scintigraphic study. Some hemodynamic parameters were then correlated with the ratio between upper and lower third of lung scan (U:L ratio) taken as a numerical index of the base to apex distribution of lung blood flow. The U:L ratio had a positive correlation coefficient with the mean pulmonary wedge pressure (MPWP) but the dispersion of individual data was wide. Dividing the patients into groups according to the level of MPWP and to the location of U:L ratio either above or below the regression line, variance analysis showed that a highly significant part of this dispersion can be accounted for by pulmonary vascular resistance (PVR). The same conclusion was reached using different statistical approaches. These findings suggest that inversion of pulmonary blood flow is not only associated with elevation of MPWP and increase of vascular resistance in the dependent lung zones but also with a rise in the general PVR. Furthermore, the cardiothoracic ratio, as index of the heart size relative to the chest cage and, therefore, of the parenchymal compression in the lower lung zones, also proved statistically and at the individual level responsible at least in part for this dispersion. Considering these multiple influences on the regional distribution of lung blood flow in these cardiac patients, a very close correlation between U:L ratio and MPWP is not to be expected. Consequently, an estimate of MPWP from U:L ratio is open to great uncertainties. Furthermore, our data show that, at the same level of MPWP, U:L ratio is higher when PVR is higher. This observation means that PVR increases and pulmonary perfusion inversion develops to some extent independently from the actual value of MPWP. We then suggest that water filtration in the lung interstitium may be ruled out as a factor responsible per se for these changes and can only be retained as a mechanism initiating them. We postulate that functional and pathologic changes in the lung vessels and interstitium may develop on the basis of a different individual response to a given stimulus.

Studies of regional ventilation in asthma using 81mKr.

Functional images of pulmonary ventilation during tidal breathing can be obtained with a gamma camera by adding a continuous flow of radioactive krypton-81m (half-life = 13 sec) to the inspired air. The procedure is readily repeatable and provides ventilation images.81mKr ventilation scans were obtained in six asthmatic patients in various phases of the disease. During acute exacerbations, while chest x-rays showed only large-volume lungs, ventilation scans were grossly abnormal, showing large, segmental, or even lobar areas of reduced ventilation as well as an increase in size of the lung images. Similar alterations, although less pronounced, were shown in patients with mild-to-moderate shortness of breath and wheezing. Bronchodilators immediately improved the ventilation defects and reduced lung size. There was further improvement and eventual restoration of normal patterns following prolonged hospital treatment.

Fatal peripheral airway cystic disease in a young woman

Diffuse cystic transformation of both lungs was rapidly fatal in a 33-year-old woman. This disorder, a rare congenital condition in infants, has apparently not been described in adulthood.

Perfusion Scintigraphy Compared With Pulmonary Arteriography in the Diagnosis of Pulmonary Embolism

From August 1976 through February 1978, 108 suspected cases of pulmonary embolism were studied. In 31 patients, the scintigraphic diagnosis and the findings of pulmonary emboli detected at pulmonary arterial angiography were compared in order to assess the specificity of pulmonary scanning. Of the 108 patients in whom pulmonary embolism had been diagnosed by perfusion lung scan, 77 did not undergo pulmonary angiography: 46 because angiography was not available, 27 because of very severe illness, and four because of the opposition from relatives or from the attending physician. In the remaining 31 patients, a total of 36 pulmonary angiographies were performed, and the results compared with the corresponding perfusion scan findings. In four patients, the contrast media was injected into the main pulmonary artery; the remaining 32 examinations were performed after positioning the injection catheter at different lobar branches, chosen on the basis of the perfusion lung scan findings. In six patients, pulmonary arterial angiography was performed after pulmonary embolism had been treated by continuous heparin infusion, when all of them showed significant improvement in the perfusion lung scan pattern (in five cases pulmonary angiography had also been performed previously, at the time of early diagnosis).

The Deposition of Labeled Aerosols in Lung Disorders

Regional deposition of aerosols in the human lung is affected by conditions that change the characteristics of the bronchial tree. An important question is whether different airway disorders are characterized by specific patterns of regional deposition of labeled aerosols [1–4]. From experimental work on the penetration of aerosols into the airways, it is known that the site and mechanism of deposition is related to the particle size [5–7]. Hence, to investigate the pulmonary and ventilatory factors affecting deposition in lung disorders, particles in a very narrow size range should be employed.