|Year : 2021 | Volume
| Issue : 6 | Page : 302-305
Persistent left superior vena cava presenting as brain abscess: A case report
Neha Mohan Rao1, Guruprasad Hassan Shankar1, Bhakti U Sarangi1, Sanjay Bafna1, Priscilla Joshi2, Rahul Jahagirdar1
1 Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
2 Department of Radiology, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
|Date of Submission||25-Aug-2021|
|Date of Decision||20-Sep-2021|
|Date of Acceptance||26-Sep-2021|
|Date of Web Publication||19-Nov-2021|
Dr. Bhakti U Sarangi
Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune - 411 043, Maharashtra
Source of Support: None, Conflict of Interest: None
A persistent left superior vena cava (PLSVC) draining into the left atrial appendage can exist as an unidentified right-to-left shunt often with no demonstrable evidence of hypoxia on history but predisposing to life-threatening clinical implications. We present a 7-year-old boy with a brain abscess who was incidentally noted to have features of hypoxia on examination. His evaluation revealed the presence of a PLSVC on computed tomography pulmonary angiogram, draining into the left atrium, thereby acting as a right-to-left shunt explaining the brain abscess. He underwent a craniotomy with a course of intravenous antibiotics, remained well on follow-up, and was referred for definitive surgery for PLSVC. Children with unidentified right-to-left shunts may present with brain abscesses in the event of which both intracardiac and extracardiac shunts have to be ruled out with the help of history, a focused clinical assessment, and more advanced imaging.
Keywords: Brain abscess, computed tomography pulmonary angiogram, hypoxia, persistent left superior vena cava, right-to-left shunt
|How to cite this article:|
Rao NM, Shankar GH, Sarangi BU, Bafna S, Joshi P, Jahagirdar R. Persistent left superior vena cava presenting as brain abscess: A case report. J Pediatr Crit Care 2021;8:302-5
|How to cite this URL:|
Rao NM, Shankar GH, Sarangi BU, Bafna S, Joshi P, Jahagirdar R. Persistent left superior vena cava presenting as brain abscess: A case report. J Pediatr Crit Care [serial online] 2021 [cited 2021 Nov 27];8:302-5. Available from: http://www.jpcc.org.in/text.asp?2021/8/6/302/330732
| Introduction|| |
Persistent left superior vena cava (PLSVC) draining into the coronary sinus and right atrium accounts for the most common congenital anomaly of systemic veins within the thorax; however, PLSVC draining directly into the left atrium remains a rare occurrence with multiple potential complications. Individuals with PLSVC can often have unidentified systemic hypoxia due to the right-to-left shunt, coming to light only with the development of a complication. Such children require a structured evaluation to rule out all the intracardiac and extracardiac shunts responsible for hypoxia. We hereby report a boy with a brain abscess who had concurrent chronic hypoxia that was secondary to the presence of a PLSVC draining into the left atrium and discuss the approach in the evaluation of hypoxia in such cases.
| Case Report|| |
A 7-year-old boy was brought with projectile vomiting for 15 days, fever, and a dull aching headache for 10 days with decreased activity and interest in his surroundings, loss of appetite and loss of weight, and preference to sleep. At the time of admission, his Glasgow coma scale was 15/15. His neurological examination showed normal tone and power, with exaggerated deep tendon reflexes and the presence of meningeal signs. In addition, his saturation in room air was noted to be 85% which improved to 90% with supplemental oxygen at FiO2 of 60% with the absence of any respiratory symptoms. He had grade 2 clubbing with a normal respiratory and cardiovascular system examination. He was admitted with a working diagnosis of meningitis with raised intracranial pressure (ICP) with severe hypoxemia and started on appropriate measures for raised ICP, intravenous antibiotics (ceftriaxone and vancomycin), steroid (dexamethasone), and supplemental oxygen.
Laboratory investigations revealed leukocytosis with neutrophilic predominance while workup for tuberculosis including Mantoux test and endotracheal aspirate for acid-fast bacilli was negative. Fundus examination showed grade 1 papilledema. His sensorium deteriorated over the next 24 hours. Magnetic resonance imaging of the brain showed large multiloculated abscess involving the left frontoparietal lobes, causing severe mass effect, and right-sided midline shift [Figure 1]. He underwent an emergency fronto-temporoparietal craniotomy and abscess evacuation with capsule for the same. Postoperatively he transiently developed anisocoria, but a repeat computed tomography (CT) of the brain showed no worsening bleed with a reduction in the midline shift. He was extubated following surgery and antibiotics were continued. Pus and tissue samples did not grow any organism.
|Figure 1: MR of the brain (T1 postcontrast) showing two well defined oval lesions in the left frontal lobe, suggestive of an infective etiology-brain abscesses|
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For evaluation of his hypoxia, an arterial blood gas (ABG) done showed a paO2 of 44 mmHg, with normal pH and pCO2 (7.47/30.4/44/21.7/0.6, sO2 83.6%). His paO2 on ABG remained low (55 mmHg) even on supplemental oxygen and he had no polycythemia. Chest radiograph and screening echocardiogram were normal. A contrast echocardiogram was then performed to evaluate the presence of a pulmonary shunt, but after agitated saline injection, it did not show evidence of the right-to-left shunt across the interatrial septum. Portosystemic shunting was ruled out by doppler of the portal system. Methemoglobin levels done were normal. CT-pulmonary angiography was done to rule out anatomical shunts and showed duplication of superior vena cava (SVC) due to PLSVC draining into the left atrial appendage, suggestive of a right-to-left shunt [Figure 2], explaining the hypoxemia, and the paradoxical embolic phenomenon (brain abscess). Cardiology opinion was sought and the patient has been advised surgical correction of the same in view of the presence of life-threatening complications of the shunt. Antibiotics were continued for 6 weeks and child remained well on follow-up with no neurological deficits.
|Figure 2: (a) Axial postcontrast computed tomography angiography images revealing an abnormal enhancing structure anterior to the aortic arch on the left (red arrow) enhancing to the same extent as the superior vena cava (blue arrow) suggestive of a persistent left superior vena cava. (b) Coronal reformatted postcontrast computed tomography angiography image obtained in the venous phase showing persistent left superior vena cava draining into the left atrial appendage (white arrow head). The blue arrow in the figure denotes right superior vena cava. The red arrow shows the abnormal left superior vena cava|
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| Discussion|| |
Although the presentation in this case was primarily neurological, our attention was drawn to the presence of features suggesting chronic, but well-compensated hypoxia with clubbing and poor weight gain. Among the five mechanisms of hypoxia, low FiO2 was not plausible. No hypoventilation was noted clinically along with a normal pCO2 on ABG. Alveolar to arterial oxygen gradient (A-aDO2) was high (56 mmHg) which occurs in ventilation-to-perfusion (V/Q) mismatch, shunt, and diffusion limitation. The absence of respiratory symptoms and signs on history and examination made the possibility of V/Q mismatch and diffusion limitation unlikely. An echocardiogram ruled out an intracardiac shunt followed by the consideration of the presence of abnormal hemoglobin which was also excluded with no saturation gap on the ABG and normal methemoglobin levels. Following this, the investigation proceeded to a stepwise evaluation for the presence of extracardiac shunt.
A PLSVC, which was first described by Raghib et al. is usually asymptomatic and detected incidentally. These patients may have saturations in the range of 85% to 95% and may have clubbing or polycythemia. In about 90% of the patients, a PLSVC drains into the right atrium through the coronary sinus and causes no clinical symptoms,, and therefore the true prevalence of PLSVC is unknown. In about 10% of the patients, the PLSVC drains into the left atrium through a partially or completely unroofed coronary sinus causing mixing with the pulmonary venous blood resulting in hypoxia. The estimated prevalence of PLSVC ranges from 0.2% to 3% in the general healthy population while being the most common congenital anomaly of the thoracic venous system, occurring in 3%–8% of the patients with congenital heart disease. A PLSVC can be seen with or without a normal right SVC. Cardiac abnormalities reported with PLSVC include dextrocardia, double outlet right ventricle, atrioventricular septal defect, polysplenia, or asplenia, which are all in the spectrum of heterotaxy and coexist with PLSVC in about 50%–70% of the cases. Other cardiac conditions associated include coarctation of the aorta, ventricular septal defect, bicuspid aortic valves, tetralogy of Fallot, and double aortic arch while noncardiac associations include esophageal atresia, VACTERL anomalies, and CHARGE syndrome. The association of aneuploidy (Trisomy 21, Turner syndrome, and microdeletion 22q11.2) with PLSVC has been reported. The level of shunting in PLSVC depends on the relationship between resistance to flow within the vessel and compliance of the ventricles, the number and size of veins and the presence of a coexisting cardiac defect if any. However, if the shunting is significant, it can cause severe cyanosis, syncope, decreased exercise tolerance, progressive fatigue, thromboembolic events, brain abscesses, and even recurrent bronchiolitis and wheezing.
About 15% of cerebral abscesses are classified as cryptogenic. In these situations, pulmonary arteriovenous (AV) malformations, atrial septal defects, patent foramen ovale, and congenital venous malformations should be considered. The etiology of brain abscesses in these patients is usually a hematogenous spread of infection from a distant source.
Implications of PLSVC depend on the drainage site and the accompanying cardiac anomaly. Suspicion in an asymptomatic patient arises during the placement of central venous catheter during cardiac catheterization, placement of pacemaker, or implantable cardioverter defibrillator, and during cardiopulmonary bypass. A PLSVC may cause abnormal anatomical and electrical communications within the atria, promoting the generation of arrhythmias, especially atrial fibrillation. Dilatation of the coronary sinus leading to stretching of the AV node and bundle of His, and possibly partial occlusion of the mitral valve may lead to cardiac arrhythmias.
Diagnosis is usually made as an incidental finding during cardiovascular imaging or surgery while an abnormal course of the cardiac catheter on chest radiograph raises suspicion. A contrast echocardiogram may be helpful in diagnosis. In our patient, agitated saline was injected into the right brachial vein, and no apparent bubbling was noted in the left side of the heart on echocardiography. Repeating the test with an intravenous catheter in the left forearm may have shown bubbles in the left side of the heart raising further the suspicion of pulmonary shunting. Transthoracic or transesophageal echocardiography is of value to demonstrate PLSVC but requires injection of agitated saline in both upper extremities. On the other hand, if the bubble echo shows the presence of a shunt but the anatomical location is unclear, agitated saline must be injected from the lower extremities or during tilt table manipulation.
Computed tomography pulmonary angiogram or magnetic resonance venography may also help establish the diagnosis if echocardiogram windows are limited and are useful to carefully delineate exact anatomical details. Cardiac catheterization for precise anatomical delineation is suggested and may aid in both diagnosis and therapy. When PLSVC drains into the left atrium and there is an adequate-sized right SVC, the PLSVC can be ligated. If the blood vessel is not adequate in size or there is no right SVC, PLSVC can be reanastomosed to the coronary sinus. Tomar has reported the use of a transcatheter Amplatzer vascular plug as well in the presence of a bridging vein connecting the two SVCs.,
In the absence of congenital heart disease, the diagnosis of a PLSVC is challenging. Brain abscess in a case with left SVC draining to the left atrium with intact coronary sinus is an extremely rare entity and requires a high index of suspicion.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient's legal guardian has given the consent for images and other clinical information to be reported in the journal. The patient's legal guardian understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
The Pediatric Intensive Care Team and Neurosurgery team at Bharati Vidyapeeth Medical College, Hospital and Research Centre, Pune.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]