Authors

• Margarita Brida — University of Zagreb School of Medicine, University Hospital Centre Zagreb, Zagreb, Croatia — ORCID: 0000-0001-8754-8156
• Maja Strozzi — University of Zagreb School of Medicine, University Hospital Centre Zagreb, Zagreb, Croatia — ORCID: 0000-0003-4596-8261
• Darko Anić — University of Zagreb School of Medicine, University Hospital Centre Zagreb, Zagreb, Croatia — ORCID: 0000-0002-7378-944X

Abstract

Atrial septal defects (ASD) are the most common heart defect in adult patients and are often diagnosed late. This defect should be suspected whenever echocardiographic imaging finds an enlarged right ventricle. We report two cases of patients with newly-diagnosed ASD that were older than 50 years of age. In both cases the patients presented with arrhythmia (atrial fibrillation, i.e. total atrioventricular block), and a successful correction of the defect was performed. If there are no contraindications, that is primarily the development of significant pulmonary hypertension i.e. pulmonary vascular resistance, the active approach – defect closure – is recommended, since it significantly contributes to clinical improvement and reduction in mortality.

Keywords

adult congenital heart disease, atrial septal defect, echocardiography, pulmonary hypertension, Amplatzer occluder

DOI

Full Text

## Introduction Atrial septal defects (ASD) are one of the most common congenital heart defects, and according to data more than 50% are diagnosed in adulthood. Right-to-left communication should be suspected whenever echocardiographic imaging establishes that the right side of the heart is enlarged. Closure is indicated for ASD when there is a significant defect of ≥10 mm and indication of right ventricular volume overload, but with no indication of notable pulmonary vascular resistance (<5 Wood units). Closure should also be considered in patients with suspected paradoxical embolizations, if other causes have been eliminated. (1) Percutaneous closure is the method of choice for ostium secundum ASD if the defect is not too large (<38 mm) and if an adequate rim is present, minimally 4-5 mm, on which the device can be anchored. Surgical closure is indicated when the defect is large, has no adequate rim, and if there is danger of damage to the surrounding tissue. (2) Echocardiographic imaging has become the dominant method for diagnosis and assessing size, rim anatomy, anomalous pulmonary veins, and surrounding structures. Today, 3D echocardiographic imaging is an additional tool that helps us better visualize the above elements. (3, 4) The benefits of ASD closure are many. Physiologically, the right ventricle is reduced in size while the left ventricle improves in both size and function. (5) Patients move to a lower New York Heart Association (NYHA) class shortly after defect closure, and physical capacity improves even regardless of NYHA class and age. (6) Finally, in addition to physiological and symptomatic improvements, it has been shown that closure of significant ASD improves survival as well. Patients that did not undergo intervention have a significantly shorter survival rate and higher mortality in comparison with the general population as well as increased morbidity from cardiopulmonary complications. In patients who underwent ASD closure early in life, ideally before the age of 24, survival rates are comparable to the general population. (7) ## Case 1 A female patient was hospitalized at the age of 58 via emergency medical service for paroxysmal atrial fibrillation and dyspnea. She had had no significant prior illnesses. Soon after hospitalization, atrial fibrillation was medically converted to stable sinus rhythm. A 12-lead electrocardiogram (ECG) showed right electrical axis deviation and an incomplete right bundle branch block. During clinical examination, a quiet systolic ejection murmur was noted over the precordium as well as a fixed split second tone. Laboratory test results were within normal ranges. Transthoracic (TTE) and transesophageal echocardiography (TEE) was performed, which showed normal size and function of the left ventricle (Figure 1). The right ventricle (RV) was enlarged, its function intact (RVEDd 4Ch 4.0 cm, FAC 37%, TAPSE 1.9 cm), with no signs of pulmonary hypertension (TR V max 2.6 m/s, VCI diam 2.0 cm, PVAccT 120 ms, PAP 32 mmHg). However, there were signs of volume overload (bowing and flattening of the ventricular septum toward left ventricle during diastole). Other than mild tricuspid insufficiency, the other valves had normal morphology and function. 3D TEE clearly showed an oval atrial septal defect (15x10 mm) localized in the fossa ovalis area with a significant left-to-right shunt (Figure 2). The ratio of pulmonary to systemic blood flow (Qp/Qs) was 2.9:1. All four pulmonary veins were seen to have adequate flow into the left atrium, with no anomalous inflow. There were no other heart defects. Magnetic resonance (MR) imaging of the heart was interrupted due to a claustrophobia-induced panic attack. Right-sided cardiac catheterization showed an elevation of saturation at the level of the RV and confirmed the diagnosis of ASD, with normal pressures in the pulmonary circulation and without significant pulmonary vascular resistance. An Amplatzer septal occluder was implanted with no complications during the procedure (Figure 3 and Figure 4); the patient was discharged the next day and was advised to take aspirin and a small dose of beta blockers. Prophylaxis of bacterial endocarditis was advised until the epithelization of the Amplatzer occluder (6 months). Figure 1. Transoesophageal short axis view of atrial septal defect. Figure 2. Transoesophageal 3-dimensional view of the atrial septal defect. Figure 3. Transthoracic short axis view at the aortic level of atrial septal defect Amplatzer occluder (arrow) at the end of the procedure. Figure 4. X-ray of atrial septal defect Amplatzer occluder at the end of the procedure. ## Case 2 A 66-year-old female patient with no previous history of severe illness was hospitalized via emergency medical service for exertion intolerance and dizziness. A total atrioventricular block was identified with a ventricular frequency of about 35/min. A pacemaker was implanted, after which the ECG showed the pacemaker spikes with QRS appearance of a right bundle branch block. TTE examination showed a relatively large ASD of the ostium secundum type, 26 mm in diameter. The pacemaker lead could be seen entering through the vena cava superior into the right atrium and going through the ASD into the left atrium, with the tip of the lead going over the mitral valve and stimulating the lateral wall of the left ventricle (Figure 5). The ASD had a dominant left-to-right shunt with signs of RV volume overload and moderate tricuspid insufficiency. Echocardiography and right-sided cardiac catheterization also showed moderate pulmonary hypertension (PAP up to 50 mmHg) with a Qp/Qs ratio of 2:1 and pulmonary vascular resistance of 3 Wood units. Surgical closure of ASD was performed, including pacemaker lead extraction and repositioning. Postoperative course was uneventful, and the patient was without significant problems after 6 months of follow-up. Figure 5. Transthoracic apical four chamber view of the atrial septal defect with a pacemaker electrode (arrow) passing through interatrial communication and stimulating the left ventricle. ## Conclusion Based on the above, a proactive approach is recommended in any patient with established significant ASD and with no contraindications for closure. Treatment decision, either interventional or surgical, is made on the basis of the individual characteristics of every patient.

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