J Clin Pathol: first published as 10.1136/jcp.4.3.316 on 1 August 1951. Downloaded from J. clin. Path. (1951), 4, 316. PARADOXICAL EMBOLISM BY B. I. JOHNSON From the Division of Laboratories, Radcliffe Infirmary, Oxford (RECEIVED FOR PUBLICATION SEPTEMBER 11, 1950) The term " paradoxical embolism " was coined by Zahn* in 1885 to describe a condition in which emboli derived from the systemic venous system reached the systemic arterial system, by virtue of an abnormal communication between the chambers of the heart. Three such cases have been observed at necropsy at the Radcliffe Infirmary, and they are considered worthy of record in so far as they illustrate the natural history of the disease, and one of them adds to the list of those in which the diagnosis cannot be doubted. In 1877 Cohnheim described a case which was almost certainly one of para- copyright. ,doxical embolism. Some writers have mentioned earlier case reports which they consider to have been examples of the condition, but it is universally agreed that Cohnheim was the first to trace the path of an embolus through a septal defect in the heart, and it seems that these earlier reports must be regarded as open to question. Even now the diagnosis must usually be a presumptive one, and it would appear difficult to make it with certainty unless the embolus could actually be found passing http://jcp.bmj.com/ through the septal defect. But it was not long after Cohnheim's report that this was in fact observed. Zahn, in 1881, reported a case in which necropsy revealed throm- bosis in the uterine vein, multiple systemic emboli, and a patent foramen ovale in which lay a branched thrombus. It must be admitted that there were some small thrombi adherent to the wall of the left ventricle, so that the systemic emboli may perhaps not have passed through the foramen; but even so, this case remains an example-the first of its kind-of a paradoxical embolus " caught red-handed." In on September 27, 2021 by guest. Protected the subsequent literature there are over 80 recorded cases of paradoxical embolism. After examination of the original reports, it was felt that the diagnosis in a few of -these was insufficiently established, but a further 39 case reports have been found in which the embolus lay in situ in the foramen ovale (Table I). Presumptive cases, * Thompson and Evans (1930), without giving a reference, stated that the term was suggested by von Recklinghausen, and this has been accepted by other writers. Zahn (1881) described his first ,case as one of " consecutive embolism," and Rostan (1884), one of Zahn's assistants, proposed the term " l'embolie croisee " in his doctorate thesis. Zahn (1885) rejected this and suggested " paradox embolie" in a paper which corrects some of the errors of Rostan's review, and in the same year von Recklinghausen (1885) put forward his theory of retrograde venous and lymphatic transport of malignant emboli; in a subsequent paper Zahn (1889) upholds his introduction of " paradoxical embolism" and discusses von Recklinghausen's paper. Welch (1899) used " aberrant embolism" for Zahn's paradoxical embolism and von Recklinghausen's retrograde embolism. Ohm (1907) -correctly attributed the term " paradoxical embolism " to Zahn. J Clin Pathol: first published as 10.1136/jcp.4.3.316 on 1 August 1951. Downloaded from PARADOXICAL EMBOLISM 317 (A CA CU CU eF CU CU - Cd :3 4) 4) cOa . <Cd 0 CT 0 4) E E o E r. C6V 5be- 0 0 0ro 0- 0 0 0 e 0. 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Protected c4 3. 0 II 4) -4 WI '.0 . 00 Ien en ; 0 cIse00 0% V 1- , _4 0 _u 4) 00 Itn 0% 0 I n 0 ~~~~ CON en 04) 180 ONa OCOO 1-4 I0% U 4) '0 I: ._~~~~~~~~~~~~.o_ 0 1 00 I.-,14) E 0 CO CO U) U) CO CO Ca6 0 oo U u u E U O COC I 0 I2 r_ 0 J Clin Pathol: first published as 10.1136/jcp.4.3.316 on 1 August 1951. Downloaded from 320 B. 1. JOHNSON though doubtless more common, are less striking, but a further 43 case reports were found in which the diagnosis appeared to be virtually certain (Table II). The case reports which have been rejected are those of Firket (1890), Buhlig (1904), Schmorl (1909), Dietrich (1925), and Armand-Delille and Lesobre (1935). Firket's (1890) four cases showed fibrinous clots passing through a patent foramen ovale, but there were no emboli in the arterial system, no venous thromboses, and only in one case (Case I) was there a pulmonary infarct and that was associated with mitral and aortic stenosis. Buhlig's (1904) case report deals with a case of miliary tuberculosis in which the foramen ovale was patent, and he suggested that emboliza- tion of tuberculous material from a primary abdominal focus took place through the interauricular defect. Schmorl's (1909) case is of interest as he regarded it as an example of reversed embolism in which a portion of clot, formed on the walls of the left ventricle and extending down the aorta, passed through a patent foramen ovale and became lodged in the pulmonary arteries, but the account is very short. Dietrich's (1925) case is difficult to assess. It was a patient aged 51 who had been in bed with thrombophlebitis of the leg for 11 weeks, and two days before death developed pain in the chest and hemiplegia; at necropsy in addition to the changes in the leg vessels, the right jugular vein and transverse sinus were thrombosed, there were antemortem thrombi adherent to the wall of the right auricle, clots in the pulmonary artery, and a pencil patency of the foramen ovale; there was a thrombosis of the right carotid artery but no evidence of embolization.