|Year : 2020 | Volume
| Issue : 2 | Page : 109-112
Anomalous communication between pulmonary artery and left atrium: A rare cause of cyanosis
Smily Sharma1, Udit Chauhan1, Prashant Kumar Verma2, Vinod Paul2, Pankaj Sharma1
1 Department of Radiology, AIIMS, Rishikesh, Uttarakhand, India
2 Department of Pediatrics, AIIMS, Rishikesh, Uttarakhand, India
|Date of Submission||08-May-2020|
|Date of Decision||02-Jun-2020|
|Date of Acceptance||23-Jun-2020|
|Date of Web Publication||15-Dec-2020|
Dr. Udit Chauhan
Department of Radiology, Division of Interventional Radiology, AIIMS, Rishikesh, Uttarakhand
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sharma S, Chauhan U, Verma PK, Paul V, Sharma P. Anomalous communication between pulmonary artery and left atrium: A rare cause of cyanosis. J Med Evid 2020;1:109-12
|How to cite this URL:|
Sharma S, Chauhan U, Verma PK, Paul V, Sharma P. Anomalous communication between pulmonary artery and left atrium: A rare cause of cyanosis. J Med Evid [serial online] 2020 [cited 2021 Apr 13];1:109-12. Available from: http://www.journaljme.org/text.asp?2020/1/2/109/303549
| Introduction|| |
Anomalous communication between the pulmonary artery and the left atrium (LA) is an unusual but potentially correctable congenital anomaly that is of interest to both physicians and surgeons. It may be considered a variant of pulmonary arteriovenous fistula; however, it is not a direct connection between an artery and a vein. Its larger calibre and shorter length facilitate a large right-to-left shunt.
The lesion can be diagnosed by contrast echocardiography and selective angio cardiography. However, the use of computed tomography pulmonary angiography (CTPA) or cardiac magnetic resonance imaging (MRI) with dynamic pulmonary angiography can obviate the need for diagnostic cardiac catheterisation. Management relies on surgery of the fistulous communication, which helps in a complete cure.
Given the rarity of this anomaly, we present a case of an adolescent male with a large fistula between the right main pulmonary artery (RPA) and LA, which led to cyanosis, polycythaemia and systemic embolisation in the form of brain abscess and splenic infarct.
| Case Report|| |
A 17-year-old male presented to our institute with on-and-off fever for 1 month and two episodes of generalised tonic-clonic seizures in the past 4 days. He was conscious and oriented and had no similar seizure episodes in the past. His birth and developmental history were unremarkable. However, right from the age of 2 years, progressive bluish discolouration of his body was noticed by his parents for which he was referred to various medical facilities but had no significant relief.
On general physical examination, the patient had high-grade fever (101 F°) and mild (28/min) tachypnoea. Central as well as peripheral cyanosis was present with Grade 3 clubbing [Figure 1]. On systemic examination, hyperdynamic cardiac apex was present with regular and normal S1 and S2. Neurological examination revealed brisk deep tendon reflexes (Grade 2 biceps and knee jerks) with unequivocal plantar reflex and normal tone. His respiratory and abdominal examinations were within normal limits.
|Figure 1: General physical examination of the patient showing bluish discolouration of the lips and tongue and Grade III clubbing in the fingers|
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His complete haemogram revealed polycythaemia. In view of seizures with high-grade fever, a lumbar puncture was undertaken, which revealed 15 cells (neutrophil predominant) with normal sugar and proteins.
His chest radiograph (CXR) showed convexity of the pulmonary bay and left atrial appendage. The right hilum was prominent with an extra radiodensity seen beyond the right heart border, giving a 'double-density sign' [Figure 2]a.
|Figure 2: (a) Chest radiograph posteroanterior view showing convex pulmonary bay (arrow) with prominent right hilum and soft tissue extending below the right hemidiaphragm (star). (b) Coronal reformatted maximum intensity projection image of computed tomography pulmonary angiography showing an aneurysmally dilated outpouching (circle) connecting the right main pulmonary artery (star) to the left atrium (rectangle). (c and d) Volume rendering technique images of the heart showing anomalous vessel (circle, outlined in the first image) connecting the posterior aspect of the right main pulmonary artery (star) to the left atrium (rectangle). (e and f) Axial contrast-enhanced computed tomography thorax showing all pulmonary veins (arrowheads) draining into the left atrium and multiple small major aorto pulmonary collateral arteries (arrows)|
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On clinical analysis, we realised that chronic cyanosis was the root cause of the disease. We tried to rule out several possible aetiologies of cyanosis. The respiratory cause was unlikely due to normal vesicular breath sounds, normal lung fields on CXR and normal pulmonary function tests. To rule out the haematological cause (methemoglobinaemia), high-performance liquid chromatography was performed, which was also normal. Cardiac pathology was rendered doubtful due to normal echocardiography?. In view of the hyperdynamic cardiac apex and subtle radiographic findings pertaining to the pulmonary artery, CTPA was planned.
CTPA with contrast-enhanced computed tomography (CT) scan of the thorax was done on 128-slice Siemens Somatom Definition FLASH 128 slice CT (Erlangen, Germany) with 50 ml of intravenous non-ionic contrast media (300 mg I/ml, iobitridiol) at a rate of 3.5 ml/s using an automated pressure injector. An aneurysmally dilated outpouching/anomalous vessel was seen connecting the posterior aspect of the RPA to the LA [Figure 2]b, [Figure 2]c, [Figure 2]d. The anomalous vessel had a maximum calibre of ~ 4.7 cm. Lung parenchyma in the immediate vicinity showed low attenuation. All the four pulmonary veins were seen draining into the LA separately [Figure 2]e. Few small tortuous major aorto pulmonary collateral arteries were seen arising from the descending aorta, coursing through the bilateral hila and supplying both the lungs [Figure 2]f. No other anatomic anomaly in heart or major thoracic vessels was seen. In the visualised upper abdominal sections, a wedge-shaped hypo-enhancing area was seen at the upper pole of the spleen [Figure 3]c with no evidence of thrombosis in splenic vessels, therefore indicating embolic infarct.
|Figure 3: (a) Axial non-contrast head computed tomography image of the head showing a hypodense lesion with hyperdense rim and perilesional oedema in the left temporal lobe-brain abscess. Note is made of diffuse hyperdensity involving intracranial vessels and dural sinuses – consistent with polycythaemia. (b) Magnetic resonance imaging of the brain showing abscess in the left temporal lobe with haemorrhage at the periphery: features detailed in text. (c) Coronal contrast-enhanced computed tomography image of the upper abdomen showing a wedge-shaped hypodense area at the upper pole of the spleen suggesting an embolic infarct. (d) Pathophysiology of the anomalous communication between the right main pulmonary artery and the left atrium|
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The patient underwent non-contrast CT scan of the head for evaluation of seizures, which showed a lobulated hypodense lesion with a hyperdense rim in the left temporal lobe. Diffuse hyperdensity involving the Circle of Willis, other intracranial vessels and dural venous sinuses was seen – findings consistent with polycythaemia [Figure 3]a. Contrast-enhanced MRI of the brain was done on 3-Tesla GE discovery 750w 3T MRI (Chicago, Illinois, United States). A well-defined lobulated lesion was seen in the left temporal lobe (~2.8 cm × 2.7 cm × 4.6 cm), which was hypo-intense on T1-weighted image (T1WI), hyperintense on T2WI and showed partial suppression on fluid-attenuated inversion recovery. The lesion had T1W hyperintense/T2W hypointense rim and showed moderate perilesional oedema. The central part of the lesion showed diffusion restriction, and the periphery showed blooming (indicating haemorrhagic contents). Thick post-contrast rim enhancement was seen. Features were suggestive of left temporal lobe brain abscess with haemorrhage at the periphery [Figure 3]b. Ultrasound of the abdomen showed a wedge-shaped hypoechoic area in the spleen and mild free fluid in the peritoneum with no genitourinary anomalies.
The final diagnosis of 'anomalous communication of RPA to LA' with normal drainage of all the four pulmonary veins into LA: 'Type 1 (De Souza e Silva et al.)' was made. The right-to-left shunt created by this anomalous communication explained the cause of cyanosis, polycythaemia, embolic brain abscess and splenic infarct [Figure 3]d.
The patient was advised neurosurgical drainage of brain abscess. However, the parents did not give consent for surgical intervention and so he was kept on intravenous antibiotics. He was referred for surgical ligation of anomalous communication between the RPA and LA. Unfortunately, he left against medical advice and was lost to follow-up.
| Discussion with Review of Literature|| |
Direct communication between RPA and LA is a rare variety of cyanotic heart disease. The first case was described by Friedlich et al. in 1950., In a review done in 2005 by Chowdhury et al., only 59 cases had been reported in the literature. Of the connections described, communication of the LA is more common with the posterior part of RPA than with the left pulmonary artery.
No definite embryological basis has been found, but some authors have quoted it to result from a primitive fistula between one of the main pulmonary veins and the pulmonary arteries. Later on, the main pulmonary vein gets incorporated into the left atrial wall, but the fistula may remain. The deoxygenated blood in the pulmonary artery follows the path of least resistance and therefore bypasses the lung. This results in central cyanosis with decreased arterial oxygen saturation.
There can be varied presentations from very severe in newborns to a milder form in older adults, depending on the right-to-left shunt's magnitude. It can complicate into congestive cardiac failure in newborns, whereas older children present with cyanosis and clubbing of digits as was present in our case. In addition to cyanosis, secondary polycythaemia may occur and complications such as haemoptysis, paradoxical embolisation to the systemic circulation and even rupture of the anomalous connection may occur. Neurological complications have been found in 20% of cases, which formed the chief presenting complaint in our case.
Associated anomalies such as atrial septal defects are common and should be sought for. This malformation is suspected when certain entities such as an unroofed coronary sinus, left superior vena cava draining into the LA or an atrial septal defect with elevated right atrial pressure and a right-to-left shunt are found.,, Classically, three types have been described by de Souza e Silva et al.,, Ohara et al. added the fourth type.
- Type I: An anomalous vessel connecting the posterior aspect of the RPA to the LA is present, with all the pulmonary veins draining normally into the LA
- Type II: Absence of right inferior pulmonary vein is seen with a fistulous connection present at the site where it normally opens into the LA. This type is associated with right lung anomalies such as absent one or more lobes
- Type III: An aneurysmal pouch is present between the RPA and LA, with all the pulmonary veins draining into it
- Type IV: Replacement of right inferior pulmonary vein by three small veins is seen, which are connected to the aneurysmal pouch. Left-sided pulmonary veins drain directly into the LA.
Surgical correction has been found to completely cure the anomaly, and early intervention is preferred to prevent the long-term effects of chronic hypoxaemia., Deaths from this malformation have usually been reported in neonates and have been attributed to additional cardiac anomalies such as patent ductus arteriosus and patent foramen ovale, which rapidly lead to cardiac failure due to large volume overload on the left ventricle.
| Conclusion|| |
Direct communication between the RPA and the LA as a cause of right-to-left shunt has been described only in a handful of cases. However, it remains a potentially correctable anomaly, and early surgical intervention should be considered to prevent the long-term complications of chronic hypoxaemia and cyanosis. CT pulmonary angiography is a very useful tool for definitive diagnosis as can be highlighted from our case, thereby obviating the need for invasive diagnostic cardiac catheterisation.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]