Consideration of Spontaneous Closure of Atrial Septal Defect by Thrombus in a Patient with Pulmonary Hypertension

Case Report / By /

Aaron Monga1, Jaspreet Thind1, Abdullah Naji1, Monica Chappidi1, Suraj P. Rasania12

Author Affiliations
1Western University of Health Sciences College of Osteopathic Medicine of the Pacific, Pomona, CA
2Department of Medicine, University of California: Riverside, Riverside California, Riverside, CA
PNWMSRJ. Published online November 2nd, 2021.

Abstract:

Introduction & Objective: Pulmonary hypertension is defined as elevated mean pulmonary arterial pressure >= 25 mmHg at rest. It is subdivided into 5 different groups, one of which is group 1 pulmonary arterial hypertension (PAH), an important cause of which is atrial septal defect (ASD). The presence of concomitant PAH and ASD is a significant consideration when deciding whether a patient’s ASD can be surgically repaired. It has been previously shown that surgical repair of an ASD in a patient with severe PAH may worsen right heart failure and cardiac output. Our goal is to present an additional case demonstrating a similar phenomenon to promote further studies.

Case Presentation: We present a case of a patient with a concomitant past medical history of PAH and ASD diagnosed by transthoracic echocardiogram a year ago who presented with end stage New York Heart Association class 4 pulmonary hypertension. The patient was known to have poor medical follow up and poor medical compliance contributing to a rapid decline in cardiac function. Upon evaluation with a more recent transthoracic echocardiogram, the patient was also found to have an atrial septal aneurysm, a closed atrial septal defect and a thrombus in the right ventricle.
Conclusion: Through this case we explore the possibility of spontaneous ASD closure and hemodynamic deterioration secondary to thrombus formation related to the atrial septal aneurysm.

Introduction:

Pulmonary hypertension is defined as an elevated mean pulmonary arterial pressure >= 25 mmHg at rest. It affects about 1% of adults worldwide, but in those above the age of 65, it affects around 10% [1]. Pulmonary hypertension is separated into five different groups. Of most relevant to our case is Group 1 pulmonary arterial hypertension. This is defined as an increased pressure in the pulmonary arterioles but with normal pressures in the capillaries and pulmonary veins. This group often involves congenital heart defects such as left to right shunts and can lead to pulmonary hypertension as well as an eventual switch to a right to left shunt which is called Eisenmeinger’s syndrome (ES). Other causes can be idiopathic, heritable, drug and toxin induced, associated with HIV, associated with connective tissue diseases, and/or due to schistosomiasis [2].

One of the most common complications from pulmonary hypertension is right ventricular hypertrophy which can increase oxygen demand for the myocardial tissue and eventually lead to right heart failure from chronic damage [2]. The most common symptoms are progressive exercise dyspnea as well as fatigue. These nonspecific symptoms are part of the reason why pulmonary hypertension goes undiagnosed for many years [3]. Diagnosis is by echocardiogram or right and left heart catheterization showing increased pressures in the pulmonary artery [2].

Being a main contributor to group 1 pulmonary hypertension, atrial septal defects (ASD) are one of the most common congenital heart defects, making up 25-30% of such cases. ASDs may initially be asymptomatic, however many patients eventually develop symptoms such as exertional dyspnea. Most cases are diagnosed in adulthood because of the late presentation of symptoms. The constellation of symptoms and abnormal cardiac physical exam findings may indicate a structural heart defect, however, definitive diagnosis of ASD is made by transthoracic echocardiogram. ASDs can be categorized by the specific embryological defect resulting in varied locations of the developed lesion. Ostium primum defects are generally located in the lower atrial septum, making up 15% of all ASDs [4]. In comparison, ostium secundum defects are generally located in the fossa ovalis region, making up 75% of all ASDs [4].

Case Presentation:

The patient is a 53 year old female with a past medical history of hypertension, type 2 diabetes mellitus, atrial septal defect diagnosed by transthoracic echocardiogram 1 year ago and pulmonary hypertension on IV Remodulin who presented to the emergency department with shortness of breath and altered mental status. The patient had a long history of pulmonary hypertension of unknown duration that was being treated at another institution and a history of medication noncompliance and poor medical follow up. The patient’s history was unable to be obtained due to intubation and sedation, so information was found via chart review. Before the entire case is described, it is important to note that the ASD which was diagnosed previously by echocardiogram 1 year ago, was found to be spontaneously closed on the transthoracic echocardiogram performed this visit. Although this could represent a new finding, it is important to consider that the previous ASD could have simply not been detected due to the limitations of the transthoracic echocardiogram.

Upon presentation to the emergency department, the patient was hypoxic with oxygen saturation at 80%, she failed a trial of BiPAP and was subsequently intubated. Her systolic blood pressure was between 180-190 mmHg. Physical exam showed jugular venous distention up to the angle of the mandible, tachycardia, and 1+ pitting edema bilaterally. Bloodwork revealed a troponin of 2.4 ng/mL, and a blood natriuretic peptide of 718 ng/mL. ABG showed a pH of 7.33, pCO2 of 33mmHg, pO2 of 65mmHg and HCO3 of 17.4 mEq/L. EKG showed no acute ST elevations or depressions but did show right heart strain. A blood culture showed no organisms and influenza swab was negative.
A Transthoracic Echocardiogram revealed a cardiac ejection fraction of 65-70%. In addition, the interatrial septum bowed toward the left atrium consistent with elevated right atrial pressure. Transthoracic echocardiography demonstrated atrial septal wall aneurysm with closure of the atrial septal defect by a fixed homogeneous echo-mass that is consistent with a thrombus. These atrial septal wall findings were different from the patient’s previous year-old transthoracic echocardiography report, which demonstrated a secundum atrial septal defect that was located in the middle of the atrial septum, and was small in size. Therefore, the closure of the atrial septal defect by a thrombus is a more recent development and can possibly be a contributing etiology to the patient’s acute deterioration of health. There was a flattened interventricular septum consistent with right ventricular overload. Right ventricular systolic pressure was 90-100mmHg. There was a dilated inferior vena cava and there was an echogenicity at the apex of the right ventricle suspicious for an apical thrombus. Furthermore, it was noted that there was a massively dilated right ventricle causing left ventricular collapse. Lastly, recommendations were made to perform a transesophageal echocardiography on the patient to definitively confirm the possibility of thrombus formation occluding the atrial septal defect, to assess for a possible intracardiac shunt and its direction, and to calculate the shunt’s Qp/Qs. However, the patient’s deteriorating and unstable condition, and the subsequent prompt transfer to a quaternary medical center prevented the opportunity of performing a transesophageal echocardiography and the assessment of a possible shunt.
In the ICU the patient was maintained on levophed, nitric oxide, milrinone, heparin and insulin drips. She remained on a ventilator with an FiO2 of 100%, PEEP of 10mmHg, respiratory rate of 17 beats per minute and tidal volume of 480mL. Throughout her admission, the patient was unable to ween off the ventilator and required increased PEEP and vasopressor support. The patient was diagnosed with end stage New York Heart Association class 4 pulmonary hypertension. Although It was unconfirmed if her pulmonary hypertension was group 1, her clinical course supports that this was most likely. Eventually she was determined to have a very poor prognosis and was transferred to a university hospital in hopes of higher level of care.

Discussion:

Most ASDs are asymptomatic until later in life, therefore ASDs are often diagnosed in adulthood. In fact, ASD is the most common congenital heart abnormality in adults. Surgical repair of ASDs has been available for decades, and generally has been shown to be a safe modality for treatment of these defects. Surgical repair of ASDs are indicated in patients with functional impairment and without concomitant pulmonary hypertension [4]. However, in patients receiving surgical repair for their ASD, operative mortality, which is defined as mortality occurring intraoperatively or within 30 days of the operation, has been shown to be higher in older patients compared to younger patients [5]. This may be explained by the cardiac remodeling that occurs in the presence of life-long ASD, resulting in hemodynamic stability dependent on the presence of the ASD. Nonetheless, closure of the ASD is recommended even in elderly patients due to reduction in morbidity and mortality [5].

Initially the symptoms that arise due to an ASD, such as exertional dyspnea, are consistent with its intrinsic left-right shunting. However, in some cases, right sided cardiac remodeling changes in the presence of a life-long ASD may cause the left-right shunt to reverse, resulting in ES. ES is a contraindication for surgical closure of the ASD [6]. Long-term presence of left-to-right shunts also put patients at an increased risk of developing pulmonary arterial hypertension (PAH) [7]. The exact contribution of ASD to the development of PAH is still up for debate but the hemodynamic relationship between the two is undeniable. The presence of PAH has been shown to worsen clinical deterioration in patients with ASD [8]. Furthermore, the severity of a patient’s PAH must be considered when deciding whether to surgically repair an ASD. Choosing to surgically close an ASD in a patient with severe PAH may exacerbate right heart failure and adversely affect the cardiac output resulting in hemodynamic instability [9]. In certain cases where the severe idiopathic PAH cannot be explained by the size of the ASD, surgical closure of the ASD has been shown to not be beneficial [10]. This unique relationship between ASD and PAH makes it particularly difficult to medically manage when presenting concomitantly.
In addition, our patient had a year-long history of ASD that has not been previously surgically repaired. Current echocardiogram findings revealed a bowing of the atrial septum from the left atrium to the right atrium, consistent with a septal aneurysm [11]. Aneurysms have been known to disrupt laminar blood flow in affected areas, increasing the risk of thrombus formation in the region of the atrial septum. In 2019, Wang et al discussed a patient with an organized thrombus overlying an atrial septal aneurysm [12]. As discussed previously, it has been shown that closing of an atrial septal defect with underlying severe pulmonary hypertension can lead to deterioration of the hemodynamic status [9]. Our patient was found to have an atrial septal aneurysm as well as a thrombus in the right ventricle. Given this patient’s evident clot formation there is a possibility that a thrombus could have obstructed the atrial septal defect causing an abrupt hemodynamic deterioration. It should be noted that a patient presentation of respiratory distress in the setting of a thrombus in the right ventricle should first prompt a work-up for possible pulmonary embolism. Nonetheless, if all other workup for hemodynamic collapse in the setting of concomitant ASD, atrial septal aneurysm, and pulmonary hypertension fails to find an adequate cause, we recommend further workup to rule out possible thrombus formation within the atrial septal aneurysm.
A discussion regarding the possible treatment options and alternatives are also warranted in patients with severe PAH. Lung and/or heart transplantation is the definitive treatment option for patients that have severe right sided heart failure and severe symptomatic PAH that are refractory to medical management [13]. However, there are alternate treatment options available as well. Interestingly, another viable treatment option is the creation of a left to right shunt. It has also been recommended that patients with severe PAH and a history of ASD or patent foramen ovale defects do not have them surgically repaired. This is advantageous as it has the ability to shunt blood flow to bypass pulmonary vasculature and increase systemic blood flow and therefore tissue perfusion. This can be achieved by either balloon atrial septostomy or placement of a Potts shunt via transcatheter approach [14, 15, 16]. Both of these procedures have the potential to be utilized as temporizing measures before transplantation or as palliative treatment options. It is important to note that it is recommended that previous ASDs should not be closed. However, both bring considerable mortality risk and are therefore rarely performed unless transplant is not readily available [14, 15, 16]. It is also uncertain how these procedures could be utilized in this case of a possible spontaneous closure of an existing ASD as the current literature is extremely limited. Further research is therefore needed.

Conclusion:

Our patient presented with a case of end stage PAH along with an atrial septal defect. Upon further evaluation, the patient was also found to have an atrial septal aneurysm. Given the echocardiogram findings of a clot in the right ventricle, we discussed the possibility of a clot forming in the atrial septal aneurysm as well. For future consideration, we recommend further workup to rule out atrial septal thrombus in patients with concomitant ASD, PAH, and atrial septal aneurysm. Through our case study, we hope to inspire future research focusing on atrial septal thrombus formation from an atrial septal aneurysm and its potential effects on patients with concomitant PAH and ASD. Further research on the spontaneous closure of an ASD by a thrombus causing hemodynamic deterioration should also be considered.

Learning Points:

  • Patients with pulmonary hypertension with concomitant atrial septal defect may develop atrial septal thrombi which may possibly have an impact on hemodynamics
  • A rare presentation of pulmonary hypertension has been presented to promote a discussion about how we approach patients with atrial septal defects and pulmonary hypertension
  • This will inspire further research about the hemodynamic effects of spontaneous closure of atrial septal defects

Acknowledgements:

We would like to acknowledge the University of California Riverside for their help with this project.

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Article information:

Published Online: November 2nd, 2021.

Corresponding Author: Aaron Monga (aaron.monga@westernu.edu)
IRB Approval: IRB approval was not necessary for this case
Conflict of Interest Declaration: No conflicts of interest to disclose
Funding Source/Disclosure: No sources of support were provided for this study