As the infection continues and more eggs are deposited in the pulmonary arterioles, with resulting arteriolitis and blockage of many small arteries, the changes become much more marked. The striking finding is dilatation of the central pulmonary arteries (Figs. 2.62, 2.63). The main pulmonary trunk, in particular, becomes enlarged and even aneurysmally dilated at times, and on fluoroscopy can be seen to pulsate vigorously. The sweep of both pulmonary arteries may be wider than usual. There will be accentuated second degree arterial branches, and the basal arteries are usually wider and tortuous, also with visible pulsations fluoroscopically. There is no pulmonary plethora, however, and the peripheral vascular markings are normal, or more commonly, decreased. CT, with or without contrast, or selective pulmonary arteriography will show dilatation (which may be massive) of the main pulmonary artery and its central branches (Fig. 2.63), but peripherally there will be a "leafless tree with broken branches". In most patients there will be enlargement of the right ventricle and pulmonary conus, but the left heart will be normal.

There is usually a normal cardiac output and circulation time. Pulmonary hypertension is inevitable (Figs. 2.61-2.64), averaging from 18 to 65 mmHg, but at times reaching up to 110 mmHg. There is little correlation between the pulmonary pressure and the size of the pulmonary artery, because the latter is affected by direct granulomatous disease of the wall as well as by the pulmonary hypertension. The pulmonary hypertension is due to mechanical obstruction from the obliterative endarteritis, aggravated by an increased blood volume due to the liver disease and the portacaval shunts. There should be normal capillary pressure but some raised pulmonary vascular resistance, because in schistosomiasis the obstruction is at the arteriolar level (whereas in emphysema the obstruction is at the capillary level). Portal venography may rarely show shunting directly from the spleen through the diaphragm to the pulmonary veins and thence into the left atrium.

Bronchiectasis has been reported with schistosomiasis, but there is no causal relationship. The bronchiectasis is a coincidental finding and the report a little confusing! Chronic upper lobe pneumonia resembling fibrocaseous tuberculosis is a very rare manifestation, perhaps following inadequate antischistosomal therapy.

Myocardial damage due to schistosomiasis is rare. Although adult worms have been found in the coronary arteries and ova in the myocardium, cardiac failure is late and is almost always mechanical (Fig. 2.64). Although pulmonary artery aneurysms are not really uncommon, aortic schistosomiasis is rare and it can be difficult to know whether an aneurysm originated in the aorta or was the result of the spread of infection from neighboring lungs. In a single case report, schistosomal aneurysm involved the arch of the aorta in a 19-year-old African woman. CT scans showed the mass to be inseparable from the arch and descending thoracic aorta. A contrast examination showed that there was leakage, and aortography outlined the aneurysm completely. Histologically there were numerous eggs within the lung tissue, the visceral pleura, and the wall of the aneurysm. There were even eggs in the thrombus which had formed.

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Fig. 2.62 A-D. The progress of pulmonary hypertension secondary to S. mansoni. A This PA chest radiograph of a Brazilian male shows prominence of the main pulmonary artery segment and the central pulmonary arteries, with tapering of the peripheral pulmonary arteries. There is right ventricular hypertrophy which has caused rounding of the cardiac apex. There are numerous small nodular densities in both lungs due to schistosome granulomas. (Courtesy of Dr. J Phillips et al. and Radiology, 1975) B In this young Puerto Rican male there is marked dilatation of the main pulmonary artery which, together with the left pulmonary artery, resembles a mass. The peripheral lung fields are clear, because the arterial circulation is diminished. (Courtesy of Dr. H. Pagan-Saez, San Juan) C, D PA and lateral chest radiographs of a 25-year-old Puerto Rican female showing marked right ventricular hypertrophy almost filling the retrosternal space in the lateral projection. The ECG provided confirmation. The main and central pulmonary arteries are prominent in both these projections. Cardiac catheterization did not demonstrate a left-to-right shunt: autopsy showed advanced hepatic and pulmonary schistosomiasis, right ventricular hypertrophy, and hypersplenism.

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Fig. 2.63 A-D. As pulmonary hypertension worsens, the cardiovascular changes become more marked, even in quite young patients. A In this 21-year-old Puerto Rican female, there is marked dilatation of the main pulmonary artery and the central pulmonary arteries, with rapid tapering of the peripheral branches. There is moderate cardiomegaly mainly due to right ventricular enlargement. B Pulmonary angiography shows a massively dilated main pulmonary artery, with abrupt tapering of the peripheral arteries. ( The tip of the catheter is near the origin of the pulmonary artery.) Her main clinical complaint had been epigastric pain and hematemesis for about 3 years. She had splenomegaly and esophageal varices and the ECG confirmed the radiographic findings. (Right ventricular pressure was 120 mmHg, end-diastolic pressure, 22 mmHg, and right atrial mean pressure, 12 mmHg.) C The chest radiograph of a 30-year-old Puerto Rican male shows right-sided cardiac enlargement, increased convexity of the right atrium, and rounding of the cardiac apex due to ventricular hypertrophy. The main pulmonary arteries are prominent due to pulmonary hypertension. In spite of this, pulmonary function tests were normal. Cardiac catheterization (D) showed right ventricular hypertrophy and dilatation, with markedly dilated main and central pulmonary arteries. There was tricuspid insufficiency with reflux back into the right atrium. Autopsy showed generalized schistosomiasis, aneurysmal dilatation of the main pulmonary artery, and diffuse atheromatosis. In the heart only the right ventricle was dilated. (Courtesy of Dr. A. Chait and AJR, 1963) Angiography is seldom necessary if echocardiography, CT, and MRI are available.

Fig. 2.64. The end stage of cardiopulmonary schistosomiasis. There is massive enlargement of the heart, and there are small bilateral pleural effusions, secondary to congestive cardiac failure. Pericardiocentesis removed 320 cc of straw-colored fluid. Thoracotomy showed multiple tiny nodules in the lungs and thick fibrous plaques. The pericardium was greatly thickened. Histology showed granulomas involving the lungs and pericardium and causing pulmonary arteriolitis. There was no evidence of malignancy or tuberculosis. The patient, a female from Puerto Rico, was only 24 years old; she had hepatomegaly, right upper abdominal pain, and dyspnea, and had lost ten pounds in weight. She also had ancylostomiasis. (Courtesy of Dr. A. Chait and AJR, 1963).