Unrecognized Patent Foramen Ovale in Patient With Sinus Venosus-Type Atrial Septal Defect With Partial Anomalous Pulmonary Venous Return.

Abstract

CLINICIAN’S KEY TEACHING POINTS BY KENT H. REHFELDT PFO is present in approximately one-quarter of the adult population, although this defect has been noted to occur more frequently when associated with other cardiac conditions such as atrial septal aneurysm and SVASD. With both a sensitivity and specificity of approximately 90%, TEE is an excellent tool for the detection of a PFO. The use of multiplane imaging, color Doppler interrogation with reduced Nyquist limit, and injection of agitated saline with Valsalva maneuver aid in the visualization of atrial shunt through this defect. In this case, a patient with SVASD and associated anomalous pulmonary venous drainage presented for surgical repair. The prebypass TEE examination did not include agitated saline injection, as the prominent atrial shunt was easily identified by color Doppler imaging. However, after the SVASD was repaired, the presence of a previously unrecognized PFO became apparent, prompting additional surgical intervention. The decision to repair a PFO during cardiac surgery performed for other indications requires consideration because this intervention is not necessarily associated with improved outcome. However, an incidentally discovered PFO is often closed if the development of significant right-to-left shunt is possible or if the primary surgical procedure involves atrial exposure. Sinus venosus-type atrial septal defect (ASD) represents approximately 4% to 11% of all ASDs and may be associated with other cardiac anomalies, such as anomalous pulmonary venous connection and patent foramen ovale (PFO).1 The foramen ovale is an interatrial communication that functionally closes after birth, when left atrial pressure exceeds right atrial pressure. A flap defect results from failure of fusion of primum and secundum atrial septa, usually providing an intermittent communication. It is usually a benign finding and affects between 20% and 34% of the adult population.2 We describe a patient scheduled for repair of a large superior-type sinus venosis-type ASD (SVASD). Intraoperative transesophageal echocardiogram (TEE) before repair did not reveal the presence of a PFO. However, soon after successful patch repair of the ASD, a large PFO was noticeable on TEE examination, necessitating reexploration and repair of the PFO. The clinical implications of an unrecognized PFO are consequential, as it can lead to recurrent embolization. Written Health Insurance Portability and Accountability Act (HIPAA) authorization was obtained from the patient for publication. CASE DESCRIPTION A 72-year-old man with a long-standing history of nonproductive cough underwent an outpatient workup, including a chest computed tomography (CT). An enlarged pulmonary artery was seen on noncontrast CT imaging. Preoperative transthoracic examination (TTE) revealed a dilated right ventricle with no tricuspid regurgitation and was suggestive of an elevated pulmonary artery systolic pressure. He underwent a right and left heart catheterization, which showed multivessel coronary artery disease, normal pulmonary pressures, and cardiac output. These findings were confirmed by TEE, which showed a normal left ventricular (LV) ejection fraction of 55%–60%, normal valvular function, and a large ASD near the superior vena cava (SVC)–atrial junction not amenable to percutaneous closure. He was scheduled for coronary artery bypass grafting and closure of the ASD. The patient was stable hemodynamically upon induction of general anesthesia. TEE revealed a moderately dilated right ventricle with normal contractility. The interatrial septum was interrogated by midesophageal view, including 4-chamber (0°), short-axis (30°–60°), and long-axis (120°–150°) views. The midesophageal bicaval view demonstrated a 15-mm defect located at the confluence of the interatrial septum and the superior cavoatrial junction. Slight withdrawal and clockwise motion of the probe demonstrated a vascular structure, with flow draining into the contralateral side of the SVC at the cavoatrial junction. These findings were consistent with an SVASD with partial anomalous pulmonary venous return (PAPVR) of the right upper pulmonary vein (RUPV; Figure 1; Supplemental Digital Content, Clip 1, https://links.lww.com/AACR/A508). Atrial septal aneurysm (ASA) was seen with hypermobile interatrial septum on TEE imaging. No other defect was seen with color flow Doppler (CFD). Intravenous agitated saline injection was not performed because the ASD was clearly visible with 2-dimensional imaging and CFD. The above findings were discussed with the surgical team and subsequently confirmed via direct visualization after cardiopulmonary bypass (CPB). The sinus venosus-type defect was then repaired, and flow from the anomalous RUPV was directed to the left atrium using a piece of bovine pericardial patch as a baffle. The cross-clamp was removed, and the heart was filled in. With the heart ejecting, but still on partial CPB, a TEE assessment of the repair was performed. We were able to confirm closure of the SVASD as well as flow from the RUPV draining into the left atrium with appropriate pulmonary vein flow on CFD (Supplemental Digital Content, Clip 2, https://links.lww.com/AACR/A509). With the ASD closed, a large PFO was now appreciated with a significant left-to-right flow (Figure 2; Clip 3, Supplemental Digital Content, https://links.lww.com/AACR/A510). Once again, agitated saline injection was not performed, given the easily demonstrable PFO with CFD. The discovery of a large PFO was communicated to the surgical team, and a decision was made to rearrest the heart and repair the PFO. Postrepair assessment demonstrated no additional flow across the interatrial septum (Figure 3). The patient was successfully weaned from CPB with minimal vasoactive support and taken to the intensive care unit in stable condition. His postoperative course progressed uneventfully, and the patient was discharged home in good condition on postoperative day 5.Figure 1.: Midesophageal modified bicaval view before CPB. Red arrow denotes fossa ovalis where no PFO is appreciated. CPB indicates cardiopulmonary bypass; PFO, patent foramen ovale.Figure 2.: Midesophageal bicaval view, after CPB, after closure of sinus venosus-type ASD. Red arrow denotes a large PFO with left-to-right shunt. ASD indicates atrial septal defect; CPB, cardiopulmonary bypass; PFO, patent foramen ovale.Figure 3.: Midesophageal bicaval view after second CPB. Red arrow denotes fossa ovalis after closure of PFO defect. CPB indicates cardiopulmonary bypass; PFO, patent foramen ovale.DISCUSSION Superior SVASDs, as their name implies, are located at the level of the cavoatrial junction superiorly, with the defect overriding the superior aspect of the muscular interatrial septum. These defects are frequently associated with PAPVR of the RUPV, which can be seen draining anomalously into the confluence of these defects. Intracardiac shunting was not suspected during initial workup. Preoperative TEE revealed SVASD, and an anomalous pulmonary venous connection can be present as frequently as 97% of the time.3 Although right ventricular and pulmonary artery enlargement was seen on noncontrast CT, atrial and pulmonary pressures recorded during catheterization were normal. The diagnostic accuracy of PFO detection by TEE has a sensitivity of 89% and a specificity of 91%4 when compared to confirmation by autopsy, cardiac surgery, and cardiac catheterization. TEE evaluation of PFO anatomy includes standard transverse (0°), longitudinal (90°) plane, and a slow sweep from 30° to 120° in the midesophageal view to track the PFO tunnel. The PFO begins in the center of the right atrial side of the septum and emerges on the anterosuperior wall of the left atrium.2 Interrogation with CFD is ideally accomplished at a lower Nyquist limit. Echocardiographic evaluation for PFO can be challenging in the presence of a large SVASD, as blood preferentially flows through it, resulting in no observable flow through the PFO. A bubble test, after a sustained Valsalva maneuver, is considered a gold standard for PFO detection. However, an elevated left atrial pressure can prevent bubble crossover. If suspicion of an atrial shunt remains, agitated saline injection can be performed during CPB, although the sensitivity of this test will be influenced by relative pressures in the atria, location of contrast injection, and potential uptake of contrast by the venous cannula before arrival at the fossa ovalis region. Performing a bubble study before terminating CPB is appropriate and may result in timely surgical intervention and avoidance of returning on CPB. A less well-known association has been described between SVASD and PFO. Samiei et al5 studied 187 patients with SVASD and found an incidence of PFO of 45%. In contrast, PFO was present in just 18.5% of control subjects. In addition, a high statistical association between PFO and ASA (54%) has also been shown,6 and both morphological abnormalities were independent predictors of embolic events. Apropos to this if an ASA is apparent in TEE, it is obligatory for the surgeon to exclude a PFO (Table). Table. - Intraoperative TEE Evaluation of Patients Undergoing Open Repair of SVASD Evaluation Comments Hemodynamic and ventricular function assessment Direction and severity of intracardiac shunting Dilation of the receiving cardiac chamber Exclude other interatrial septal defects Precise information on location and number of ASDs A septal defect appears as a loss of continuity Evaluate for abnormal flow pattern using color Doppler. Color M-mode, PW, and CW Doppler examination Delineation of PAPVR Most common form is anomalous drainage of the right upper pulmonary vein into the RA or into the base of the SVC Document pulmonary veins draining into the LA to exclude PAPVR Assess for potential PFO defect High association of PFO with atrial septal aneurysms Exclude significant and potentially treatable residual defects before weaning off bypass Association of PFO finding in SVASDa (1 study) Request surgeon to examine for PFO during repair Image optimization for PFO detection Use bubble study with agitated saline and Valsalva maneuver both before and after SVASD repair Post-SVASD repair checklist ASD patch is intact and no residual shunt SVC draining correctly into the RA No turbulent flow in SVC Confirm normal pulmonary venous flow by PW Doppler Assess for PFO defect, include bubble study Consider hemodynamic effects of ASD closure Abbreviations: ASD, atrial septal defect; CW, continuous wave; PAPVR, partial anomalous pulmonary venous return; PFO, patent foramen ovale; PW, pulsed wave; RA, right atrium; SVASD, superior vena cava atrial septal defect; SVC, superior vena cava.aEchocardiographic assessment in the perioperative period during open repair of a SVASD. Parameters for quantifying PFO size include PFO length, diameter, and distance of foramen ovale from SVC and aortic annulus.7 A large PFO reveals a septal separation of approximately 2 mm or more.8 A PFO was not detected until after SVASD closure. Our inability to detect PFO before CPB could be related to nonperformance of a bubble study, with our focus directed toward to the obvious ASD. Although the appearance of the new atrial shunt was consistent with PFO in this case, creation of a de novo ASD is possible after attempted ASD repair and underscores the need for a thorough interrogation of the atrial septum. The question remains whether closure of a PFO appreciated during surgery is necessary. Incidental PFO is not associated with increased perioperative morbidity.9 Surgical closure is unrelated to long-term survival and may increase postoperative stroke risk.10 However, the benefits of PFO closure may be difficult to prove in the absence of large randomized trials with sufficient follow-up. PFO repair is appropriate when right-to-left shunting is significant, as during LV assist device placement. Sukernik and Bennett-Guerrero9 propose that a PFO should be closed when development of a significant right-to-left shunt after surgery is highly likely, and when almost no alteration of the surgical plan would be needed. The decision to close a PFO is based on the size of the PFO and a history of possible paradoxical embolism.10 An ASA has been described as a protrusion of the aneurysm of at least 15 mm beyond the plane of the atrial septum.11 It can be an isolated abnormality, or found in association with coexisting PFO, ASD,6 and mitral valve prolapse.12 The PFO was closed notwithstanding the risks related to rearresting the heart and returning to full CPB. Reasons for PFO closure included preventing right ventricular volume overload from persistent PFO-related shunt. A PFO associated with an ASA is a more important predictor of recurrent stroke than shunt size.13 A missed PFO may contribute to cryptogenic stroke burden, although this is by no means proven in observational trials. Consensual statements on institutional requirements for PFO closure for prevention of paradoxical embolic stroke have been developed based on data from clinical trials from percutaneous device closures.4 A PFO discovered after CPB requires an individualized decision by the perioperative team, taking into account the degree of intracardiac shunting, risk for stroke, and ability to tolerate additional time on CPB. Evaluation of this repair should include a thorough interrogation of the interatrial septum, both for closure of the primary defect, as well as for the presence of a previously unobservable PFO.14 It is pertinent that the surgeon carefully seek the possible coexistence of a PFO in a large SVASD during CPB. DISCLOSURES Name: Joseph Capone, DO. Contribution: This author helped prepare the manuscript and obtain the still pictures and video clips. Name: Irwin E. Brown, DO. Contribution: This author helped guide manuscript preparation, including proofreading. Name: Jayanta Mukherji, MBBS. Contribution: This author helped coordinate, and additionally contribute to, the manuscript. This manuscript was handled by: Kent H. Rehfeldt, MD.