Spectrum of Findings of Sinus Venosus Atrial Septal Defect: CT and MR Findings

Spectrum of Findings of Sinus Venosus Atrial Septal Defect: CT and MR Findings Poster No.: P-0026 Congress: ESCR 2015 Type: Scientific Poster Authors: J. M. Madrid, P. J. Mergo, P. Bartolomé, J. Phelan, P. Parikh, 1 2 2 2 1 1 2 2 2 A. Bowman, B. Shapiro ; Pamplona/ES, Jacksonville, FL/US Keywords: Congenital, Diagnostic procedure, MR-Angiography, MR, CTAngiography, Cardiovascular system, Cardiac Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.escr.org Page 1 of 27

Purpose To review from an educational point of view the radiologic manifestations of sinus venosus atrial septal defect. Images for this section: Page 2 of 27

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Fig. 1: VRT image demonstrating a sinus venosus defect (SV) in continuity with an anomalous right pulmonary vein (PAPV). Page 4 of 27

Methods and Materials Five cases of sinus venosus atrial septal defect were collected from the report records of the Department of Radiology at Mayo Clinic, Jacksonville, Florida. In collaboration with the Radiology Department of Clínica Universidad de Navarra, we review the clinical behaviour, imaging findings and final diagnosis of this uncommon disease. Results Prevalence Atrial Septal Defect (ASD) is the most common congenital heart defect to present in adulthood (1). ASD accounts for 5% to 10% of all cases of congenital heart disease (2). ASD can be caused by a defect of ostium secundum (80%), ostium primum (10%), unroofed coronary sinus (<1%) and sinus venosus (SVASD), which is reported to represent approximately 2-10% of all cases of ASD (2) (Figure 2). Embryology ASD can be classified in two types: A) Direct communicatiom between the right and left atria: ostium primum and ostium secundum. B) Does not involve the interatrial septum but physiologically behaves like interatrial septal defects: sinus venosus and unroofed coronary sinus (1). Most of the atrial septal defects derive from a development alteration of the interatrial septum, which is the structure that divides the primary atrium into the right and left atrial chambers. On the other hand, the exact embriology development of sinus venosus defect is controversial. It is thought to result from the lack of septation between the pulmonary veins and the superior cava vein or right atrium (1) (Figure 3). Anatomy The are two types of SVASD: the superior and the inferior SVASD. The superior form constitutes the majority and also the most well recognized type while the inferior SVASD, also known as "Right atrial type SVD", is rare with only case reports and small case series published (as shown in Figure 21). Page 5 of 27

The anatomic alteration is localized: in case of superior SVASD, there is a defect communicating the right atrium-svc junction with the left atrium; in the case of inferior SVASD, a communication exists between the right atrium-ivc junction with the left atrium (1,3,4). In the 80-95% of patients an associated anomalous right pulmonary venous drainage is evident (3-5); a partial anomalous pulmonary venous return (PAPVR) of the right upper lobe into the SVC in patients with superior SVASD, and a PAPVR of the right lower lobe pulmonary vein into the pericardial segment of the IVC or right atrium in patients with inferior SVASD. The pathognomonic feature of SVASD is the overriding of the intact rim of the fossa ovalis by the cava vein and the presence of a shunt at the atria level (4) (Figure 2). Clinical behaviour Although ASD represents the most common congenital heart defect presenting in adulthood, it can be clinically silent for decades (1). SVASDs produce a left-to-right shunt. Long-standing shunting leads to dilatation of the right-sided chambers and enlargement of the pulmonary arteries. Eisenmenger pathology may manifest due to the chronic overload of the right-sided chambers. This right side overload leads to permanent pulmonary hypertension. A pulmonary-to-systemic blood flow ratio (Qp:Qs ratio) of greater than 2:1 will likely be symptomatic and require surgical intervention by age 40. When symptomatic, clinical manifestations of SVASD are variable and nonspecific, including dyspnea, paradoxical embolism, fatigue, recurrent pulmonary infections, arrhythmias, palpitations and right chamber dilatation (1,6). Imaging -Transthoracic and transesophageal echocardiography: Although transesophageal echography (TEE) has demonstrated good detection rates in the past (4,5), a review by Kafka et al. of 37 patients with right ventricle dilatation without a known cause by transtorathic ecography (TTE) or (TEE) revealed that nineteen of the patients were ultimately diagnosed with SVASD using MRI. Additionally, eighteen of them had anomalous pulmonary venous connections, all of them right-sided (4). Additionally, although the detection rates by TTE may be less than 12% (5,6), the American College of Radiology recommends TTE as the initial diagnostic imaging modality in adults with suspected or known cardiac congenital malformations. Page 6 of 27

The utility of TEE is limited by its invasive nature and by its inherent inability to image the cranial aspect of SVC, where accessory right upper lobe pulmonary veins sometimes connect makes this modality less (7). -Cardiac CT: The complex anatomy of the heart may make differentiation of type, size and extent of an ASD difficult. The modern post-processing techniques of computed tomography angiography (CTA) are ideally suited for such complicated anatomy and pathology. Compared with the centrally located secundum ASD, the sinus venosus is located eccentrically, either superior or inferiorly in the atrial septum at the sites of inflow of the superior vena cava or inferior vena cava, respectively. The superior sinus venosus ASD is far more common than the inferior type (2). In cases of superior SVASDs, cardiac CT images demonstrate a defect in the superior aspect of the interatrial septum at the level of the superior vena cava. This defect may allow a communication between the left atrium and superior vena cava. Chronically, this defect may result in volume overload of the right heart chambers, leading to enlargement of the right atrium, the right ventricle and the pulmonary artery, with development of pulmonary arterial hypertension. On superior SVASDs, cardiac CTA imaging with a saline chaser can show concentrated contrast material pooling in the dependent left atrium, a finding known as "fallen contrast" which is characteristic of a right-to-left shunt (1). -Cardiac MR (CMR): CMR is an excellent noninvasive imaging modality in the evaluation of SVASD. CMR provides accurate information about the cardiac anatomy, ventricular volumes and function, and allows flow quantification measurements (7). CMR may depict SVASD anatomy and associated anomalous pulmonary venous drainage, provide quantitative information on the hemodynamic burden and may delineate the presence of additional cardiovascular abnormalities. CMR may provide the surgeon with an excellent road-map for successful and uncomplicated surgical intervention. CMR imaging techniques utilized for evaluation of SVASD may change in the future, due to newer techniques and sequences. Currently, a complete CMR protocol to diagnose a Page 7 of 27

suspected SVASD may include: ECG-triggered, breath hold gradient echo cine MR for assessment of SVASD and pulmonary venous anatomy and for quantitative evaluation of ventricular volumes and function; Gadolinium enhanced three dimensional magnetic resonance angiography with maximum intensity projection images; and flow velocity quantification in the ascending aorta and in the main pulmonary artery to calculate the pulmonary-to-sistemic flow ratio (Qp:Qs ratio) (7). -Cardiac catheterization: Cardiac catheterization has been used as a preoperative imaging modality, however, its invasive nature and exposure to ionizing radiation are significant drawbacks (7). Treatment and prognosis Surgical repair of SVASD is usually recommended, as early as possible, because the age-related decrease in left ventricular compliance increases the left-to-right shunt. Compounded by the presence of anomalous pulmonary venous drainage, right heart volume overload may occur more readily than with other types of ASD, with resultant development of right heart failure and secondary pulmonary hypertension (8). The basic principle of repair is redirection of the PAPVR through the interatrial communication into the left atrium. The surgical procedure is more complex than other types of ASDs, with an increased risk of stenosis of the SVC or pulmonary veins, residual shunting and sinoatrial node dysfunction. Different surgical techniques are uitilized, depending on the anatomy of the defects and the preferences of the surgeon. The usual surgical approach involves a median sternotomy and cardiopulmonary bypass with moderate systemic hypothermia (25-32ºC). Repairs divert the PAPVR through the SVASD into the left atrium. This diversion require a pericardial patch (8). The prognosis for these patients is excellent. There is a low complication rate and low postprocedural mortality. The survival rate is similar to that expected in age and gender matched controlled populations. Symptomatic improvement is achieved in the 77% of patients, especially in older patients. However, postoperative sinus node dysfunction is more common than following secundum ASD repairs, due to either anatomic anomaly of the sinus node or surgical trauma caused by proximity of the SVASD to the sinus node. Page 8 of 27

New-onset atrial fibrillation is a potential complication, especially in older patients. The mechanism is due to scar-dependent multiple reentries or increased size and fibrosis of the atrium, secondary to increasing pulmonary venous pressure. Images for this section: Fig. 2: Anatomy of the interatrial septum defects (from the right atrium perspective). Note the localization of superior and inferior sinus venosus defect, close to cava vein drainage (red ovals). Also is identified the mechanism of patent foramen ovale (arrow). Ostium primum defect (green oval). Ostium secundum (pink circle). CS=coronary sinus. Page 9 of 27

Fig. 3: Cardiac embriology with a main focus on sinus venosus and cava veins genesis Page 10 of 27

Fig. 4: CTA image demonstrates an anomalous pulmonary vein (A) draining into the superior vena cava. Page 11 of 27

Fig. 5: CTA image at the level of the sinus venosus defect showing free communication of the right and left atria via the sinus venosus defect (SV). Page 12 of 27

Fig. 6: CTA image more inferiorly demonstrates the drainage of the right middle lobe and right lower lobe pulmonary venous branches into the left atrium. The anterior venous branch (A) depicted here is in continuity with the sinus venosus ASD seen more cranially on the previous image. Page 13 of 27

Fig. 7: MIP reconstruction nicely demonstrates the sinus venosus atrial septal defect (SV) and the anomalous pulmonary vein (PAPV) in continuity with the sinus venosus defect (draped over the right pulmonary artery (RPA). Page 14 of 27

Fig. 8: Separate patient with CTA images demonstrating a sinus venosus ASD. Page 15 of 27

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Fig. 9: CTA image in the same patient at a more cephalad level shows the anomalous right superior pulmonary vein (PAPV) draining into the superior vena cava near the junction with the right atrium. Fig. 10: Volume rendered reconstruction (VRT) of CTA in the same patient with a venous phase injection. The anomalous right superior pulmonary vein (PAPV) is shown draining into the superior vena cava (SVC) near the junction with the right atrium (RA). Page 17 of 27

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Fig. 11: Volume rendered image (VRT) rotated 90 degress (with the left atrium and left ventricle on the left side of the image) shows the sinus venosus defect (SV) in continuity with the anomalous right pulmonary vein (PAPV). Fig. 12: MRA can be useful for demonstrating the findings of PAPVR and SVASD with the added benefit of no radiation and no nephrotoxicity. A multi-phase MRA exam is most helpful, allowing optimal visualization of the PAPVR (as shown in this case (PAPV). Page 19 of 27

Fig. 13: Coronal MRA image at a slightly different level shows the anomalous pulmonary vein (PAPV) as it enters the superior vena cava (SVC). Page 20 of 27

Fig. 15: Oblique MIP reconstruction demonstrates the sinus venosus defect (SV). Page 21 of 27

Fig. 16: CT chest in this patient shows a very large sinus venosus ASD (SV). Page 22 of 27

Fig. 17: CT image at the level of the ventricles in the same patient shows severe right atrial and right ventricular enlargement, as well as a small right pleural effusion. Note the aneurysmal atrial septum with bowing of the atrial septum to the left, as well as flattening of the interventricular septum, indicative of right heart failure (in this case with elevated RV volume and pressure). Page 23 of 27

Fig. 18: CT image at the level of the pulmonary artery shows central enlargement of the pulmonary arterial trunk consistent with pulmonary arterial hypertension. Moderate to severe pulmonary hypertension is relatively uncommon in patients with ASD (< 12% of adults at time of diagnosis). Patients with SVASD develop pulmonary hypertension at an earlier age than patients with other types of ASD. The development of severe irreversible pulmonary hypertension and Eisenmenger physiology is now uncommon, due to earlier detection and surgical intervention. Page 24 of 27

Fig. 19: IVC-type sinus venosus ASD. While most SVASD involve the SVC, the IVC can rarely be involved. It is unclear whether this type is caused by a primary defect in the closure of the septum or is related to an abnormal insertion of the IVC into the left atrium. Like the more common SVC-type, the IVC-type is also associated with partial anomalous pulmonary venous return. Page 25 of 27

Conclusion Atrial septal defects are the most common congenital heart defect to present in adulthood and sinus venosus subtype represents 2-10% of all of ASDs. Sinus venosus ASD (SVASD) is associated with partial anomalous pulmonary venos return. A left-to-right shunt can be present, which may lead to right ventricular volume overload, development of elevated right ventricular pressures and possible subsequent development of irreversible pulmonary hypertension. Surgical repair of of SVASD is usually indicated, with survival rates similar to those expected for age and gender matched controlled populations. CTA and CMR are excellent noninvasive imaging techniques which allow accurate identification of cardiac anatomy. CMR has the added value of assessment of flow measurements and function, with calculation of Qp:Qs, providing the surgeon with a superb road-map and ability for morphologic assessment, further facilitating a favorable operative outcome. References 1. Carlos a. Rojas. Embryology and Developmental Defects of the interatrial Septum. AJR Am J Roentgenol. 2010 Nov;195(5):1100-4. 2. Hugh D. White. Imaging of adult atrial septal defects with angiography.jacc Cardiovasc Imaging. 2013 Dec;6(12):1342-5. 3. Edward T.D. Hoey. Multidetector CT assessment of partial anomalous pulmonary venous return in association with sinus venosus type atrial septal defect. Quant Imaging Med Surg. 2014 Oct; 4(5): 433-434. 4. JM Oliver. Sinus venosus syndrome: atrial septal defect or anomalous venous connection? A multiplane transoesophageal approach. Heart. 2002 Dec; 88(6): 634-638. Page 26 of 27

5. Kafka H. Cardiac MRI and pulmonary MR angiography of sinus venosus defect and partial anomalous pulmonary venous connection in cause of right undiagnosed ventricular enlargement. AJR Am J Roentgenol. 2009 Jan;192(1):259-66. 6. Michael S. Donovan. Sinus Venosus Atrial Septal Defect as a Cause of Palpitations and Dyspnea in an Adult: A Diagnostic Imaging Challenge. Case Rep Med. 2015; 2015: 128462. 7. Anne Marie Valente. Cardiac Magnetic Resonance Imaging Evaluation of Sinus Venosus Defects. Comparison to Surgical Findings. Pediatr Cardiol (2007) 28:51-56. 8. Christine H. Sinus Venosus Atrial Septal Defect. Long-Term Postoperative Outcome for 115 Patients. Circulation. 2005;112:1953-1958. Page 27 of 27