Isolated Right-sided Patent Ductus Arteriosus in Right-sided Aortic Arch

protruded forward. This sequence of events is in contrast to a previous report' describing protrusion of the prevertebral soft: tissue as the initial event in obstructive apnea. The patient was completely well before the head trauma six years previously. We believe, therefore, that the main underlying cause of the obstructive apnea was an abnormal sleep-induced reduction in the pharyngeal dilator muscle tone, caused by the head injury. The combination of this, together with the elongated epiglottis and the retrognathia, then facilitated the loss of airway patency during sleep. Both abnormally decreased muscular activity! and reduced pharyngeal cross-sectional area of the pharynx have been described in patients with the obstructive sleep apnea syndrome.' When nasal CPAP was applied, the epiglottis was virtually blown into approximation with the posterior pharyngeal wall giving the patient a feeling of suffocation. The fact that the patient could not fall asleep, as well as a pneumatic tongueretaining effect of the nasal CPA~ presumably prevented marked aggravation of the obstructive apnea. It is likely that the abnormality of the epiglottis was not noted at the initial otorhinolaryngeal exammation because the patient was examined in the upright position. Most of our patients with obstructive sleep apnea are now studied by video-taped fluoroscopic examination of the pharynx during sleep. When the mechanism responsible for occlusion of the pharyngeal airway is discovered, the most appropriate treatment can be selected. As in the report from Krieger et al," the present patient illustrate's the necessity for a carefully supervised therapeutic trial of nasal CPAP prior to long-term therapy. REFERENCES 1 Sullivan CE, Berthon-Jones M, Issa FG, Eves L. Reversal of obstructive sleep apnea by continuous positive airway pressure applied through the nares. Lancet 1981; 1:862-65 2 Wagner DR, Pollak C~ Weitzman ED. Nocturnal nasal-airway pressure for sleep apnea. N Eng} J Moo 1983; 308:461-62 3 Krieger J, Sautegeau A, Sauder ~ Weitzenblum, Kurtz D. Syndromes d'ap~s du sommeil. 1hlitement par la pression positive continue par voie nasale. Presse Med 1984; 13:2559-62 4 Krieger J, Weitzenblum E, Monassier J~ Stoeckel C, Kurtz D. Dangerous hypoxaemia during continuous positive airway pressure: treatment of obstructive sleep apnea. Lancet 1983; 2:1429-30 5 Rappoport DM, Sorkin B, Garay SM, Goldring RM. Reversal of the ··Pickwicldan syndrome" by long-term use ofnoctumal nasalairway pressure. N Eng} J Med 1982; 307:931-33 6 Berry RB, Block AJ. Positive nasal airway pressure eliminates snoring as well as obstructive sleep apnea. Chest 1984; 85:15-20 7 A&.elius LE, Elmqvist D, Hougaard K, Laurin S, Nilsson B, Risberg AM. Sleep apnea syndrome-an alternative treatment to tracheostomy. Laryngoscope 1981; 91:285-91 8 Guilleminault C, Hill M~ Simmons FB, Dement WC. Obstructive sleep apnea: Electromyographic and fiberoptic studies. Exp Neuroll978; 62:48-67 9 Rivlin J, Hoffstein v Kalbfleisch J, McNicholas W, Zamel N and Bryan AC. Upper airway morphology in patients with idiopathic obstructive sleep apnea. Am Rev Respir Dis 1984; 129:355-60

Isola.- Right-sided Patent Ductus Arteriosus In Right-sided Aortic Arch· Report of lWo Cae. Morgan Ft., M.D.; Jui-Sung Hung, M.D.; Pui-Kan Uao, M.D.; and Chtm-Hdung Chang, M.D.

An isolated right-sided patent ductus arteriosus has not been reported previously to occur in right-sided aortic arch associated with an aberrant left subclavian artery. We report such anomalies in two adult patients. In the ftnt case of a 19-year-old woman, the ductus was successfuDy ligated via a left posterolateral thoracotomy; however, many technicaldifBculties were eneounterecl. In the second cue ofa 36year old woman, a right posterolateral thoracotomy enabled detailed demonstration of the ductus and its surrounding structures and facilitated its successful Ugalion. An isolated right-sided patent ductus arteriosus should be approached via right thoracotomy.

a rare association of right-sided aortic arch with patent I nductus arteriosus, the ductus usually occurs on the .left:

side as an isolated anomaly or in combination with other cardiac defects.l" When the patent ductus arteriosus occurs on the right side with a right-Sided aortic arch, it is almost exclusively accompanied by other defects such as an atrial septal defect, ventricular septal defect, and absent or hypoplastic pulmonary artery.'" There have been only four reported cases of isolated right-sided ductus associated with right-Sided aortic arch; in two children the ductus was associated with a right-sided aortic arch with mirror-image brachiocephalic branches," and in the other two children the branching pattern of brachiocephalic vessels was not specified.3.5 We report the findings in two adult patients who had right-sided patent ductus arteriosus occurring as an isolated anomaly in a right-sided aortic arch with aberrant left: subclavian artery. CASE REPORTS CASE

I

A 19-year-old girl had a cardiac murmur since the age of one month. She had been well except for frequent episodes of uppe rrespiratory-tract infection. On examination, she was moderately developed and nourished. Pulses were slightly bounding. Blood pressure was 100/50mm Hg. The heart was not enlarged, but the left ventricle was slightly overactive. The most striking cardiac findings were a continuous thrill over the right upper portion of the chest and a grade-416harsh machinery-like continuous murmur loudest in the second right intercostal space along the sternum with transmission to the left sternal border. A chest x-ray film showed a right-sided aortic arch, a normal-sized heart, and slightly increased pulmonary vasculature. An electrocardiogram and M-mode echocardiogram were normal. At cardiac catheterization, there was significant oxygen saturation step-up in the pulmonary arteries. The ratio of pulmonary to systemic blood *From the Sections of Cardiology, Pediatric Cardiology, and Cardiovascular Surgery, Chang Gung Memorial Hospital, 'Wpei, 'Wwan, Republic of China. Reprint re~: Dr. Hung, Chang Gung Memorial Hospital, 199 7bng Hwa North Road, Taipei, faiwan, ROC 10590 CHEST I 91 I .. I APRIL, 1887

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FIGURE 1. Fluoroscopic anteroposterior view, showing catheter entering aorta and then left aberrant subclavian artery via rightsided patent ductus arteriosus (PDA) from proximal right pulmonary artery (case 1).

flow was 1.6. The pulmonary artery pressure was normal. The catheter entered the aorta easily via a patent ductus arteriosus from the right pulmonary artery near Its bifurcation to the main pulmonary artery (Fig 1). Anglograms of the aortic arch showed right-sided aortic arch, right descending aorta, and right-sided patent ductus arteriosus connecting the aortic arch with the right pulmonary artery. An aberrant left subclavian artery arising as the last branch of the aorta was also demonstrated (Fig 2). Esophagograms did not show signs of external compression of the esophagus. Surgical ligation was successfully carried out via left posterolateral thoracotomy, although technical difficulties were encountered. At surgery a long ductus arising from the aortic arch near the orifice of the aberrant left subclavian artery and connecting to the proximal right pulmonary artery was identified and ligated . The postoperative course has been uneventful, and the murmur disappeared after the operation.

CASE 2 A 36-yeaMlld woman presented with exertional dyspnea, wheezIng and cough for six days. A cardiac murmur had been found ten years previously. On examination, she was moderately developed and nourished. There was no cyanosis or clubbing of the digits . Pulses were bounding, the blood pressure was 130no mm Hg, and the heart rate was 100beats per minute and regular. The heart was enlarged, and the apicalImpulse was diffuse and overactive. The first heart sound was normal , and the pulmonic component of the second heart sound was loud. There was a third heart sound. A grade-516 machinery.like continuous murmur accompanied by a palpable thrill was heard maximally In the second right Intercostal space along the sternal border and over the upper sternum, with transmission to the neck . Moist rales were present In both basal pulmonary fields. Findings from the remainder of the physical examination were not remarkable. A chest x-ray film revealed right-sided aortic arch, moderate cardiomegaly, an enlarged main pulmonary artery, and marked pulmonary plethora. An ECG was consistent with left ventricular

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FIGURE 2. injection of contrast medium In aortic (Ao) arch through catheter passed via right-sided patent ductus arteriosus (PDA) from proximal right pulmonary artery. Aortic arch gives rise to right subclavian artery (Ht Sub), right carotid artery (Ht C), left carotid artery (Lt C) and last branch, aberrant left subclavian atery (Lt Sub). Note that branching pattern of brachiocephalic arteries is of nonmirror Image. DsAo=descending aorta; and MPA=maln pulmonary artery (case 1).

hypertrophy. M-mode echocardiograms showed dilatation of the left ventricle, the left atrium, and the right ventricle. At cardiac catheterization the catheter entered easily from the proximal right pulmonary artery Into the brachiocephalic artery and the descendIng aorta via the right-sided patent ductus arteriosus. The oxymetric study was consistent with a left-to-right shunt at the level of the pulmonary artery with a pulmonary-to-systemlc flow ratio of 3.8. The pulmonary artery pressure was moderately elevated at 66/30 mm Hg (mean of 40 mm Hg). The aortic pressure was 160155 mm Hg (mean of 90 mm Hg). Aortograms showed a right-sided aortic arch and right-sided descending aorta, a large right-sided patent ductus arteriosus, and an aberrant left subclavian artery (Fig 3). The patient had no dysphagia, and esophagograms were normal . At surgery performed via a right posterolateral thoracotomy, a large and long right-sided ductus arising from the aortic arch just distal to the right carotid artery and connecting with the proximal right pulmonary artery was Identified and ligated. An aberrant left subclavian artery was noted to arise as the last branch of the brachiocephalic vessels and to course posteriorly behind the esophagus and the trachea. The patient has done well after the surgery, and the murmur is no longer present. DISCUSSION

Right-sided aortic arch is rare, and its incidence is about 0.04 to 0.14 percent in adults.' Right-sided aortic arch is classifiedinto two types based on their embryologic developments .· 1YPe 1 right aortic arch is associated with mirrorimage brachiocephalic branches. 1YPe 2 right aortic arch is associated with an aberrant left subclavian artery arising either as the last branch of the aortic arch or from an aortic diverticulum.u Isolated right-sided patent ductus arteriosus Ieollded RIght-sided PDA (Fu et .)

FIGURE 3. Delayed film of left \lentriculograms (right anterior oblique view). Catheter enters right descending aorta (Dsao) via right-s ided patent ductus arteriosus (PDA) from proximal right pulmonary artery. Pig-tailcatheter is placed in left ventricle (LV) via descending aorta and ascending aorta (AsAo). Intersection of two catheters approximates position of patent ductus arteriosus. Ao Arch= aortic arch; and MPA=main pulmonary artery (case 2).

associated with right-sided aortic arch in the absence of intracardiac defects is extremely rare, In the English literature, there have been only four such cases reported in children." Van der Horst and his associates' reported isolated right-sided patent ductus arteriosus in a six-year-old boy and a 14-hour-old female newborn associated with type 1 right-sided aortic arch with mirror-image brachiocephalic branches. These two cases were very unusual, as this type of right-sided aortic arch rarely occurs in association with a normal heart or noncyanotic heart diseases. It is associated with congenital heart diseases in 98 percent of the cases," especially cyanotic heart diseases such as tetralogy of Fallot and truncus arteriosus. 1.1 In the other two cases of isolated right-sided patent ductus arteriosus with right-sided aortic arch in an eight-year-old girl and a two-year-old girl reported by Maier et al3 and by Mahoney and Manning," respectively, there were no comments on the branching pattern of brachiocephalic arteries. Our two patients represent the first well-documented cases of isolated right-sided patent ductus arteriosus associated with type 2 right-sided aortic arch. These two cases are extremely unusual fur several reasons. First, type 2 rightsided aortic arch usually occurs as a sole cardiovascular anomaly, and it is associated with congenital heart diseases in only 12 percent of the cases.· Secondly, its association with patent ductus arteriosus is very rare, and when such a ductus coexists with thistype of right-sided aortic arch, the ductus is usually on the left side, as seen in cases with a usual left-sided aortic arch . U And thirdly, in a rare occurrence of a type 2 right-sided aortic arch with a right-sided patent ductus

arteriosus, the ductus has been combined with other anomalies such as atrial septal defect, ventricular septal defect, and absent or hypoplastic pulmonary artery. 1-3 In type 2 right-sided aortic arch, the aberrant left subclavian artery lies across the trachea and esophagus posteriorly; therefore, this type of aortic arch is often accompanied by a partial or complete vascular ring around the trachea and esophagus.'" however, this seldom causes clinical symptoms of tracheal or esophageal compression. 1 Both of our patients had a type 2 right-sided aortic arch with an aberrant left subclavian artery, and neither had any symptoms or signs of tracheal or esophageal compression. Both of our patients had a continuous murmur heard loudest at the right second intercostal space along the sternal border and over the upper sternum, a location unusually right of the site of the maximal intensity of the continuous murmur fur the left-sided patent ductus arteriosus. When a continuous murmur is noted over the right upper portion of the chest in a patient with noncyanotic congenital heart disease and a right-sided aortic arch, presence of a rightsided patent ductus arteriosus should be included in the differential diagnosis of continuous murmurs aside from coronary arteriovenous fistula, pulmonary arteriovenous fistula, ruptured sinus of Valsalva, mammary souffle, and systemic collateral artery supplying lungs as in type 4 truncus or pulmonary sequestration. In the case of right-sided aortic arch with left-sided patent ductus arteriosus, the operation is done via left posterolateral thoracotomy in the usual way.3-1 In all four reported cases of isolated right-sided patent ductus arteriosus associated with right-sided aortic arch, the ductus was successfully ligated via right posterolateral thoraeotomv.'" In our case 1, surgical ligation of the ductus was done inadvertently via left posterolateral thoracotomy, and much technical difficulty was encountered before successful ligation of the ductus was accomplished. In case 2, the surgery was done via right thoracotomy. It enabled detailed demonstration of the ductus and its neighboring structures and facilitated successfulligation of the ductus. Therefore, surgical ligation of rightsided patent ductus arteriosus should be done via ipsilateral thoracotomy.

REFERENCES 1 Hastreiter AR, D'Cruz lA, Cantez'I: Namin Ep, Ucata R. Rightsided aorta . Br Heart J 1966; 28:722-39 2 Felson B, Palayew MJ. The two types of right aortic arch . Radiology 1963; 81:745-59 3 Maier HC, Van der Woude R. Right-sided patent ductus arteriosus with right aortic arch. J Thorac Cardiovase Surg 1968; 56:401..{)1 4 Van der Horst RL, Fisher EA, DuBrow IW, Hastreiter AR. Right aortic arch, right patent ductus arteriosus, and mirror-image branching of the braehiocephalic vessels. Cardiovasc RadioII978; 1:147-49 5 Mahoney EB, Manning]A. Congenital abnormalities of the aortic arch. Surgery 1964; 55:1-14 6 Stewart JR, Kincaid ow, TItus JL. Right aortic arch: plain 81m diagnosis and significance. Am J Roentgenol Radium Ther Nucl Med 1966; 97:377-89 7 Jones JC. 'IWenty-8ve years' esperienee with the surgery of patent ductus arteriosus. J Thorac Cardiovasc Surg 1965: 50:149-65 CHEST 1111 14 1 APRIL, llil87

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