Aorta to Right Ventricular Fistula Status Post-TAVR

Introduction

Transcatheter aortic valve replacement is a minimally invasive procedure that involves replacing a damaged aortic valve using a catheter, typically inserted through a small incision in the leg, leading to faster recovery and reduced risks compared with traditional open-heart surgery. It is a common procedure; however, it is not without adverse events. Complications that may occur that can impact survival after TAVR include moderate/severe paravalvular leakage; major vascular and bleeding complications; disabling stroke; acute kidney injury; and conduction abnormalities, such as high-degree atrioventricular block with the necessity for permanent pacemaker implantation. ¹ An aorta to right ventricle/right ventricular outflow tract (RV/RVOT) fistula is a rare complication of TAVR with only a handful of case reports in the literature, ² and management of this complication is not straightforward. Here, we report a case of an aorta to right ventricular fistula after TAVR.

Case Presentation

An 83-year-old man with a past medical history of multivessel coronary artery calcifications and chronic obstructive pulmonary disease (COPD) had developed symptomatic severe aortic valve stenosis. Given his age and multiple medical comorbidities, he received the recommendation to undergo TAVR. He underwent successful TAVR with an Edwards Sapien 3 Ultra 29 mm bovine pericardial balloon expandable bioprosthesis. The immediate post-TAVR transthoracic echocardiogram demonstrated an appropriate reduction in transvalvular pressure gradient to 4 mmHg, a small pericardial effusion, and no paravalvular leak. His postprocedure electrocardiogram (ECG) demonstrated a new left bundle branch block, and on postoperative day 1, the ECG manifested with sinus rhythm with intermittent recurrent episodes of complete heart block with return to normal sinus rhythm. This required the placement of a Micra leadless pacemaker. In the postprocedural period, the patient developed atrial fibrillation with a rapid ventricular response and anticoagulation therapy was initiated with apixaban. The patient was discharged home on hospital day 4 and was instructed to continue apixaban for reduction in stroke risk.

Two days after discharge, the patient presented to the cardiology clinic at which point he reported progressive shortness of breath which he felt was much more prominent than his typical shortness of breath attributed to COPD. A repeat transthoracic echocardiogram was performed in the clinic and demonstrated a progression in the size of the pericardial effusion but no tamponade physiology. The patient was hospitalized, and his apixaban and anti-platelet medications were withheld. Serial echocardiograms demonstrated continued progression in the size of his pericardial effusion, and physical examination revealed an elevated jugular venous pressure. Repeat transthoracic echocardiogram on hospital day 6 demonstrated a large pericardial effusion with pericardial fluid approximately 6 cm anterior to the RV. The patient underwent echocardiogram guided pericardiocentesis withdrawing approximately 620 mL of hemorrhagic pericardial fluid. A follow-up echocardiogram demonstrated no significant re-accumulation of the pericardial fluid and residual pericardial fluid 2 cm anterior to the RV, and a Doppler signal transition from the right coronary cusp toward the RVOT. A transesophageal echocardiogram on hospital day 8 demonstrated a minimal residual pericardial effusion adjacent to the RV, a prominent color Doppler signal from the right coronary cusp to the RVOT, at or slightly above the level of the aortic annulus with no paravalvular regurgitation. These findings defined a potential aorta to RV outflow tract fistula with possible extension into the perimembranous septum (Figure 1, Video 1, and Video 2). As the matter of fact, on retrospect review of the initial transthoracic echocardiogram obtained in the cardiology clinic, there was indeed a substantial Doppler color signal from the right coronary cusp to the RVOT that was not immediately obvious on initial interpretation. The patient underwent cardiac computed tomography with contrast demonstrating a small aortic root (right coronary cusp) to RVOT fistula creating a perimembranous ventricular septal defect (Figure 2) as previously seen on the transesophageal echocardiogram. The cardiac shunt measured 7.3 mm in the coronal view (Figure 3).

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Figure 1.

Transesophageal echocardiogram, mid-esophageal long-axis view with color flow Doppler demonstrates a prominent color Doppler signal (arrow) from the right coronary cusp to the RVOT, at or slightly above the level of the aortic annulus.

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Figure 2.

Interval transcatheter aortic valve replacement cardiac computed tomography with angiography demonstrates a small fistulous communication (arrows) between the aortic root, right coronary cusp to RV/RVOT with extension to the left ventricular outflow tract forming a perimembranous ventricular septal defect: (A) axial view, (B) coronal view, and (C) sagittal view.

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Figure 3.

Enlarged version of Figure 2(A), demonstrating the aforementioned fistulous communication measuring approximately 7.3 mm in diameter.

The patient was discharged and initially managed with a period of close observation with frequent outpatient follow-up. He underwent right-heart catheterization 2 months after his hospitalization for further evaluation of the aorta cameral fistula, and aortogram did not reveal an obvious left-to-right shunt. Nevertheless, he continued to suffer from progressive shortness of breath, and 2 weeks later, he required hospitalization for management of acute on chronic congestive heart failure given dyspnea on exertion, peripheral edema, and an elevated brain natriuretic peptide of 882.0 pg/mL. Ultimately, the patient was transferred to a tertiary care center where he underwent successful closure of the traumatic membranous ventricular septal defect with an Amplatzer vascular plug via a percutaneous approach. The patient followed up with our cardiology clinic on postoperative day 7 where he reported a dramatic improvement in his symptoms. He reported feeling much better, with improved energy levels, and he did not have any shortness of breath.

Discussion

An aorta to RV/RVOT fistula is quite a rare complication of TAVR with only a handful of case reports in the literature. ² There is an implication that the etiology could be related to a traumatic fistula associated with the procedure, as the proceduralist must attempt to repetitively pass through the stenotic aortic valve with the catheter, often requiring multiple attempts. However, this is a theoretical suggestion. The anatomy of the right coronary cusp of the aortic valve, interventricular septum, and RV/RVOT are in proximity with one another, creating a potential for the catheter to take a path that could create a fistula. Of concern, case reports in small series had indicated that patients with this complication tend to progress to significant heart failure over the course of weeks to months. Management is not straightforward; medical management with serial observation is reasonable for asymptomatic patients, whereas therapeutic options include percutaneous closure of the aorta to RV/RVOT fistula with a septal occluder device such as an Amplatzer vascular plug for symptomatic patients with high surgical risk, or cardiothoracic surgical repair of the aorta to RV/RVOT fistula for patients with favorable surgical risk. A surgical approach is a feasible alternative, but in general, these patients are poor surgical candidates.^3,4

A systematic review of the literature indicates that conservative management with serial echocardiography seems appropriate in asymptomatic patients. It also suggests that if there is evidence of worsening heart failure, right-heart chamber dilation, or an increase in the Qp/Qs ratio is found, shunt closure should be strongly considered. ⁵ The Qp/Qs ratio refers to the ratio of total pulmonary blood flow to total systemic blood flow, and it is a useful tool for quantifying the net shunt. A Qp/Qs ratio of 1:1 is normal and usually indicates that there is no shunting. ⁶ These recommendations are confirmed by the outcomes of similar case reports. Almanfi A et al described a case of an asymptomatic patient with an aorta-right ventricular shunt after TAVR in which the patient was managed conservatively, with repeat echocardiography after 1 year showing improvement in the velocity across the shunt, and the patient remaining asymptomatic. ⁷ Shakoor et al described a case of a symptomatic patient with aorta to right ventricular fistula following TAVR in which the patient refused transcatheter repair with an Amplatzer vascular plug, was managed conservatively, progressively got worse, and ultimately changed his code status to comfort measures and passed away after a couple of days. ⁸ Indeed, our patient did require hospitalization for acute on chronic heart failure shortly after development of his aorta to RV/RVOT fistula.

We chose transcatheter shunt closure given our patient required hospitalization for acute on chronic heart failure shortly after development of his aorta to RV/RVOT fistula. Moreover, it was unlikely that an aorta to RV/RVOT fistula of 7 mm, as described in our case, would have closed on its own given its size. In addition, spontaneous closure of acquired intracardiac shunts has not been reported. ⁵ Surgical repair could have provided a definitive solution in our patient; however, he did have significant comorbidities and was not a good surgical candidate. Ultimately, the patient underwent post-TAVR percutaneous closure of the aorta to RV/RVOT fistula with an Amplatzer vascular plug.

A percutaneous approach could be relatively straightforward or may be quite technically challenging since each case provides its own anatomic variables. In such a percutaneous approach, great care would need to be taken to avoid disruption of an otherwise normally functioning transcatheter heart valve. However, this approach may expose the patient to less morbidity or mortality when compared with the surgical approach. Ultimately, the best treatment option will depend on the clinical presentation and presence of symptoms, the anatomic variables associated with the defect, and the associated surgical risk. Fortunately, our patient’s percutaneous repair went smoothly, he had significant symptomatic improvement, and there were no postoperative complications.

Conclusion

Aorta to RV/RVOT fistula is quite a rare complication of TAVR that should be considered when a patient develops symptoms of heart failure after TAVR. Close review of the transthoracic echocardiogram for Doppler signal flow that is consistent with an aorta to RV/RVOT fistula is essential. If an acquired intracardiac shunt is suspected after TAVR, TEE would be prudent as the abnormal Doppler flow is more easily identifiable given the higher sensitivity when compared with transthoracic echocardiography. Options include medical management with close observation, transcatheter repair with a septal occluder device, or cardiothoracic surgical repair. Percutaneous shunt closure in symptomatic patients using percutaneous low-profile shunt closure devices seems to be the best treatment option in high surgical risk patients.