(b) Persistent Patulous Ductus Arteriosus Botat Persistence of the cluctus I3otalli is only of clinical significance if it retains its original dimensions after birth, or increases in nidth in the course of life extra titer°. Closure normally results from a growth of tissue which arises from the spindle-cells of the media of the vessel wall especially, with contraction of the other layers of the vessel wall, begins in the centre and is as a rule still not wholly perfect before the end of the first month of life. Incomplete closure occurs, in which the duct remains permeable to a sound during life, but this is of no signifi cance. Absence of closure may depend upon abnormal nature of the wall of the duct or upon mechanical obstruction to obliteration, from imperfect respiration or disturbance in the pulmonary circulation dur ing the first days of life. In this relation congenital cardiac anomalies are the first causes, followed secondly- by atelectatic conditions of the parenchyma of the lung. The patulous ductus may either be of equal width throughout its course or it may dilate like a funnel toward the aorta, or finally it may be shortened so that aorta and pulmonary artery connnunicate directly through a common opening. Aneurysmal dilatation has been observed with disease of the wall of the duct.
The first clinical studies upon the isolated occurrence of patulous ductus Botalli were those of Almagro and Duroziez (1862) in which attention was called to the occurrence of murmurs of a peculiar sort, which may be absent in the first weeks of life but usually develop within the first six months, with increasing dilatation of the duct.
The mechanical results of patulous ductus arc increased pressure in the pulmonary artery and an increased flow of blood from the aorta into it, which in time leads to dilatation and inflammatory disease of the wall. So, too, hypertrophy and dilatation of the right ventricle must eventually result.
Patulous ductus may exist alone or in association with other con genital anomalies. Up to this time about 23 uncomplicated cases of this condition have been described anatomically.
The diagnosis of patulous ductus was evolved by Francois Franck and Gerhardt.
With any considerable dilatation of the ductus, percussion shows a band of dulness in the first two intercostal spaces, projecting for the width of a finger over the left edge of the sternum, corresponding to the dilated pulmonary artery (Gerhardt's band of dulness), which corre sponds in Rontgen pictures to a pecubar cap-shaped top above the shadow of the heart (see Fig. 115).
For the occurrence of murmurs with patulous fluctus the following conditions are necessary: (1) sufficient width of lumen; (2)a sufficient flow of blood under sufficient pressure, from the aorta on one side and the pulmonary artery o» the other, since the murmurs in question de pend upon the formation of eddies by the unequal blood current within the combined ve.ssels, ductus and pulmonary artery. As a result, then, in a ductus with small lumen, or when a patulous ductus is combined with high-grade stenosis, atresia or arrested development of the aorta or pulmonary artery, murmurs may be absent. The murmurs, almost always purely systolic in the first years of life, may be accompanied by ffiastolic murmurs in later years, as a result of inflammatory diseases of the walls of the duct and of the pulmonary artery. The murmurs
are very well transmitted to the back: Francois Franck wrongly con sidered this a specific symptom of patulous ductus.
Auscultation gives either pure heart sounds or systolic, more rarely also diastolic murmurs with their points of maximum intensity on the rnanubrium sten», well transmitted to the neck and back.
The behavior of the second sound at the aortic cartilage is of great importance in diagnosis, as it is always very considerably accentuated in pure cases and.frequently produces a palpable shaking of the chest wall with diastole (palpable rebound in the second intercostal space on the left side).
The murmur is transmitted into the earolids, more to the left than the right. With any considerable dilatation of the ductus and sufficient distribution of blood through the pulmonary artery, the vibrating arch of the aorta is palpable in the neck. With dilatation of the pulmonary artery at the same time a systolic vibration is felt in the three upper intercostal spaces to the left of the s.terrium, to which a strong palpable rebound is added in diastole.
Francois Franck laid stress upon the occurrence of pulsus para doxus (diminution in pulse-rate with inspiration and increase with expiration) in the tliagnosis of patulous ductus, yet this symptom is not in the least constant.
Just as inconstant, too, is the symptom recently made prominent by Dokuszajewx, of a decreased pulse-wave in the left half of the body, which would be well founded, theoretically, if the ductus w-ere widely patulous and the blood stream of the aorta were decidedly diverted.
In the pure forms of patulous ductus Botalli, cyanosis is almost always absent. Subjective symptoms first develop as a rule at the end of the first year or even later. Of these the most important are pal pitation, dyspncea and a tendency to pulmonary catarrh. This cardiac anomaly sometimes allows of long life, yet only a few cases have lived past 40 years.
The difficulty in diagnosis is great when patulous ductus is asso ciated with pulmonary stenosis, especially if the valves of the pul monary artery have lost their ability to oscillate, since the important symptom of accentuation of the second sound in the pulmonary area may then be absent. The differential diagnosis froni simple pulmonary stenosis is made from the palpable rebound of the second sound, from the transmission of the murmur and the palpable vibration in the neck, and, not least, from the Rontgen pictures which show an increase in the shadow of the vessels of the left side in patulous ductus, but in pul monary stenosis an atrophied or normally sized shadow (see Fig. 105).
The free communication between aorta and pulmonary artery- as the result of embryonal defect of the septum trunci, a great rarity, gives no certain symptoms of clinical value.
In older children rupture of the ductus may occur (Roder, Esser). Typically the site of the rupture is near the point of entrance of the duc tus into the pulmonary artery. Before rupture occurs, a dissecting aneurysm of the ductus and terminal portion of the pulmonary artery some times develops.