Successful Redo Surgical Replacement of a Flail Bioprosthetic Aortic Valve: A Case Report

Introduction

Over the past 20 years there has been a significant rise in use of bioprosthetic valves for surgical aortic valve replacements, now representing more than 85% of all surgical implantations [1]. Current techniques for aortic valve replacement include sternotomy, minimally invasive cardiac surgery, and transcatheter aortic valve replacement [2]. Although mechanical aortic valves have mortality benefits over bioprosthetic aortic valves among younger age groups, no such benefit was seen in patients older than age 55 years [3]. Studies showed that there was no difference in post-procedure incidence of stroke. However, due to their limited long-term durability, bioprosthetic aortic valves were associated with greater likelihood of reoperation [4]. The primary causes of aortic valve reoperation are structural valve dysfunction (42.7%), endocarditis (37.8%), non-structural valve dysfunction (17.7%), and aortic aneurysm (2.1%) [5]. Prolapsed leaflets in bioprosthetic aortic valves are rare, and there is a lack of literature on the topic. Here, we present a unique case of an early bio-prosthetic aortic valve failure due to a flail leaflet, which was replaced via sternotomy.

Case Report

A 58-year-old man (height 176 cm, weight 102.4 kg) with a history of atrial fibrillation, stent placement in the left anterior descending artery, and 2 aortic valve replacements presented to the Emergency Department for evaluation of acute onset of chest pain and shortness of breath. He previously underwent PCI to the left anterior descending artery and was treated with dual antiplatelet therapy (ASA and Plavix) for 1 year, continuing with ASA 81 mg daily indefinitely. For atrial fibrillation, he has been taking Multaq 400 mg twice daily and Eliquis 5 mg twice daily. His medical history also noted a congenital bicuspid aortic valve, leading to his first valve replacement (Saint Jude 25 mm) 16 years ago (2008) and a subsequent replacement (Medtronic Avalus 25 mm) 6 years ago (2018) due to endocarditis complicated by aortic root abscess. Both times, the patient chose bioprosthetic valves over mechanical valves.

The patient was found to be hypotensive and in cardiogenic shock, requiring multiple vasopressors, including IV levophed, IV epinephrine, and vasopressin at maximal doses. His body temperature was 37.1°C, respiratory rate was 26 bpm, heart rate was 51 bpm (peripheral), blood pressure was 47/26 mmHg with a MAP of 35 mmHg, and SpO2 was 73%. He was intubated and started on mechanical ventilation. Blood cultures were negative; a complete blood count revealed white blood cells elevated at 26.3×103/μL and no significant left shift. Chemistry revealed BUN 25 mg/dL, creatinine 2.5 mg/dL, AST 102 U/L, ALT 65 U/L, and eGFR 26.41 mL/min/1.73 m2. Venous lactate levels were elevated at 15.5 mmol/L, proBNP was elevated at 6926 pg/mL, procalcitonin was 95.90 ng/mL, and troponin was 0.6 ng/mL. An ECG revealed sinus tachycardia with first-degree AV block at 106 bpm, right bundle branch block, and left anterior fascicular block.

A chest X-ray (Figure 1) showed significant pulmonary vascular and interstitial congestion. Due to concerns about function of the prosthetic aortic valve, a transthoracic echocardiogram (TTE) was performed (Figure 2), showing normal EF of 55% to 60%, but poor image quality hindered a clear assessment of the bioprosthetic aortic valve. Consequently, a transesophageal echocardiogram (TEE) was performed (Figure 3, Video 1), revealing severe regurgitation of the prosthetic aortic valve due to flail of one of the leaflets, but without any identifiable vegetation. The patient then underwent left heart catheterization, which showed nonobstructive coronary artery disease.

The patient was then evaluated by a cardiothoracic surgeon. After a Heart Team discussion, it was determined that due to the operator’s limited experience with valve-in-valve TAVI at our facility, the most appropriate course of action would be to proceed with a redo valve replacement. The surgeon expressed the greatest confidence in performing SAVR, making it the preferred option. The patient was taken to the operating room and placed under general anesthesia. An intraoperative TEE was performed safely and showed evidence of prosthetic valve failure with complete prolapse of the noncoronary cusp. The surgeon performed a median sternotomy, and the heart was dissected and retracted. Cannulation of the distal ascending aorta and right atrium was done using antegrade cannula. Examination showed the noncoronary cusp leaflet flailing into the left ventricular outflow tract (Figure 4). The failing Medtronic Avalus size 25 mm bioprosthetic valve was removed and replaced with a size 27 mm Medtronic Avalus valve, secured with the CorKnot system (Figures 5, 6). CPB time was 88 min, anesthesia time was 4 hours 39 min, fluid balance was positive 2345 mL, and the patient received auto-transfusion (cell saver) for 76 mL during surgery. He was then transferred back to the ICU with 3 vasopressors to maintain a MAP >65 mmHg.

On postoperative day 1, the patient remained in shock with pulmonary edema, requiring vasopressors, including epinephrine, norepinephrine, and vasopressin. All 3 vasopressors were successfully weaned off by postoperative day 3. By postoperative day 5, he developed symptomatic junctional bradycardia and intermittent complete heart block, necessitating external pacing, and he underwent successful implantation of a transthoracic echocardiogram indicated normal left ventricular systolic function with an ejection fraction of 60%. The bio-prosthetic valve in the aortic position was functioning well, displaying a normal transvalvular gradient and no regurgitation.

Discussion

A bicuspid aortic valve is the most common congenital heart anomaly, found in about 1% of the overall population, with a male-to-female ratio of 2: 1 [6]. Moreover, patients with bicuspid aortic valve degeneration tend to be younger, so choosing between a mechanical or bioprosthetic valve is a more complex decision [7]. Mechanical valves last longer than bioprosthetic valves; however, they necessitate lifelong use of warfarin. Despite the risk of future valvular dysfunction, the use of bioprosthetic valves is increasing because they are hemodynamically more stable and closer to natural valves, providing better immediate patient outcomes compared to mechanical valves. Moreover, bioprosthetic valves do not require lifelong anticoagulation therapy, which is a significant advantage for many patients, especially those who cannot adhere to or tolerate anticoagulation regimens required for mechanical valves [8]. In recent years there have been significant advancements in the design and implantation of bioprosthetic aortic valves including development of stentless valves. However, randomized trials showed that there was no difference in clinical outcomes between stented vs stentless bioprosthetic aortic valves, although the latter require prolonged cardiopulmonary bypass times [9]. Another trial showed stented valves are less likely to be replaced due to dysfunction compared with stentless valves [10]. Among the stented valves, although there was no direct comparison, the PERIGON study dual-chamber permanent pacemaker on postoperative day 6. Two days after pacemaker implantation, his condition stabilized and he had an uneventful recovery, leading to hospital discharge. A postoperative transthoracic echocardiogram revealed normal EF with a well-seated bioprosthetic aortic valve without any evidence of paravalvular regurgitation (Video 2). Blood cultures taken on the first hospital day presentation remained negative after 5 days, and cultures of the explanted valve showed no growth.

After discharge, the patient was seen by a cardiologist in an outpatient clinic. The patient denied any active concerns. A reported that there was no incidence of structural valve degeneration with the Avalus valve at 5 years [11]. The key factor influencing the longevity of bioprosthetic heart valves is the patient’s age. Bioprosthetic valve failure is uncommon among patients over 70 years old, but is more frequently encountered among younger patients [12]. Prior reports suggest that at least 2–10% of bioprosthetic valves require reintervention at 10 years [13]. The increase in utilization of bioprosthetic aortic valves over the years only suggests that a significant proportion of patients are at risk for valvular dysfunction in the future. As such, it remains important to review this important clinical presentation that has only been rarely reported in the literature.

Bioprosthetic aortic valve prolapse is a form of structural valve degeneration that is often due to excessive wear and tear [14]. A wide variety of surgical bioprosthetic valves are currently available, and there are disparities among them in terms of durability and hemodynamic efficacy. Prior studies reported that Avalus bioprosthetic aortic valves have excellent durability [15]. Although previous studies reported early degeneration of other bovine pericardial valves [16], we have not found any case reports related to early degeneration of the Avalus valve. Prior studies identified several predictors of valve degeneration, including high BMI, renal insufficiency, redo surgical aortic valve replacement, and small prosthetic size [17]. Our patient had a smaller prosthesis and prior surgical AVR, which are known to be risk factors for early valve degeneration. Although there were prior case reports of valve-in-valve transcatheter aortic valve implantation for failed surgical valves, a second redo surgical AVR was performed on our patient. As such, due to the inherent complexity of the clinical scenario and surgical technique, this case report may provide useful information for future surgeries.

Conclusions

Flail leaflet of bioprosthetic aortic valves is an uncommon but life-threatening clinical condition that necessitates immediate clinical recognition and management. Redo surgical replacement is a feasible treatment option to manage flail bioprosthetic aortic valves.