Evaluation of incidence of structural valve deterioration in patients with Freestyle aortic valve | ||||
Minia Journal of Medical Research | ||||
Article 24, Volume 34, Issue 1, January 2023, Page 190-198 PDF (588.66 K) | ||||
Document Type: Original Article | ||||
DOI: 10.21608/mjmr.2023.183856.1265 | ||||
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Authors | ||||
Areej Muhammad Alkadi Muhammad ![]() | ||||
1Department of Radiodiagnosis, Faculty of medicine, Minia | ||||
2Department of Cardiology, faculty of medicine, Tanta university, Egypt | ||||
Abstract | ||||
Background: The Freestyle aortic root bio prosthesis is a complete porcine aortic root implanted by different techniques: sub coronary, root inclusion, or complete aortic root replacement. The choice among the three implant techniques depends on surgeon preference or upon the pathology encountered. Its implantation is done by open heart surgery. The study aimed to trace the prevalence of sub clinical leaflet thrombosis in patient underwent free style aortic valve replacement, and how far is the need for anticoagulation therapy to protect the patients from being involved in transient ischemic attacks (TIAs) or strokes. Method: This study enrolled 47 patients underwent Freestyle aortic valve and had MDCT at least with two follow up point interval post operative. We evaluated the cusp structure and possible sub clinical thrombosis using a retrospective ECG gated CT angiographic study. Results: We observed 22 cases with positive thrombus out of 47 with percentage of 46%, with negative relationship between thrombus formation and oral anticoagulant taking. The cumulative incidence of thrombus was increasing over years. Conclusion: Sub clinical thrombus formation is a common complication over Freestyle bioprosthetic valve and makes oral anti-coagulant taking mandatory | ||||
Keywords | ||||
sub clinical thrombosis; oral anticoagulant; retrospective ECG; porcine aortic root | ||||
Full Text | ||||
Introduction Aortic valve lesions are the most common valvular pathology in the developed countries. The incidence of the pathology increases with growing ages after 65 years. Aortic valve replacement (AVR) is recommended for symptomatic aortic valve disease according to the guidelines of American Heart Association for management of patients with valvular heart disease, such as small aortic root, aortic aneurysm, or dissection. Also, it had been reported to be a successful treatment option in the destructive aortic valve endocarditis1
The Freestyle aortic root bio prosthesis is a complete porcine aortic root implanted by different techniques: sub coronary, root inclusion, or complete aortic root replace-ment. The choice among the three implant techniques depends on surgeon preference or upon the pathology encountered. Its implantation is done by open heart surgery2.
It offers excellent hemodynamics in indicated patients, however, as with all biological prostheses, structural valve deterioration (SVD) limits its durability, eventually necessitating reintervention3
One of its complications is subclinical leaflet thrombosis which is predominantly hemodynamically silent and not detected by transthoracic Echocardiography in most patients. Echocardiography is used to assess transvalvular pressure gradient and effective valve orifice area. Mean aortic valve gradients is significantly higher in patients with reduced leaflet motion than in those with normal leaflet motion.4
Multi-slice computed tomography (MSCT) is needed for the accurate characterization of the valve. In post-contrast MSCT, subclinical leaflet thrombosis is defined as the presence of reduced leaflet motion, along with corresponding hypoattenuating lesions. We quantitatively assess leaflet
motion at maximal leaflet opening during systole using a three-dimensional volume-rendered en-face image of the prosthetic valve5
Aim of the work We aimed in our study to trace the prevalence of sub clinical leaflet thrombosis in patient underwent free style aortic valve replacement, and how far is the need for anticoagulation therapy to protect the patients from being involved in transient ischemic attacks (TIAs) or strokes. This was done by using MSCT in evaluating the valve morphology, its function, and the possible complication.
Patients & Methods This is a retrospective study conducted in Radio-diagnosis Department, at Aswan Heart Centre including the patients who underwent freestyle aortic root replacement between 2011-2019 and had MSCT. Patients were selected according to the following inclusion and exclusion criteria: Inclusion criteria: This study included patients underwent Freestyle aortic root replacement.
Exclusion criteria:
Detailed description of the performed procedure:
Data acquisition:
Image reconstruction and post processing:
between the Sino tubular junction and proximal aortic arch at the level of the main pulmonary artery).
The analysis of the data was carried out using the IBM SPSS version 20.0 statistical package software (IBM; Armonk, New York, USA). Normality of the data was tested using the Kolmogorov-Smirnov test. Data were expressed as mean ± SD for parametric quantitative data and median (IQR) for non-parametric quantitative data, in addition to both number and percentage for qualitative data. Paired samples t-test and Wilcoxon signed rank test were done to compare parametric and non-parametric data, quantitative data of follow ups respectively. While independent samples t- test was done to compare parametric quantitative data between two groups. The Chi‑square test and Fisher’s exact test were used to compare categorical variables. Pearson’s correlation was done for non-parametric data. A p-value less than 0.05 was considered significant.
Results Demographic data: This study enrolled 47 patients (23 males and 24 females), underwent replacement of aortic valve with Freestyle aortic valve and had at least two follow up studies post-operative (table1). Ca score: Regarding calcification (Figure 1), it was measured from different parts of the aortic root, the data of Ca score from some cases were missed as they had not been scanned with Ca score. It was obvious that the calcification was a common complication, and it was increasing significantly over years with P value=0.001 (Chart 1). It is figured out that the annulus is the most affected part to be calcified with percentage of affection in comparison with all other areas= 69.6% (Chart 2).
Aortic diameters: The ascending aorta diameters were measured at every follow up study. All aortic measurements were within average diameter with no stenosis or dilatation. There was significant increase in the diameters of sinus of Valsalva and STJ as well as proximal aortic arch with P value >0.05, while no significant changes in other segments of the ascending aorta. (Table 2). Leaflet thrombosis: Thrombosed leaflet was observed in 22 cases from the 47 cases with percentage of 46% (table 3). There was a strong negative relationship between thrombus formation and use of oral anti-coagulants (chart 3). The cumulative probability of a thrombus was increasing over years from 1 year follow up post-operative to 10 years (chart 4). Discussion Freestyle aortic valve is a porcine bioprosthetic valve implanted by several techniques regarding surgeon’s preferences. The ideal valve substitute for the aortic valve should have superior hemodynamics, no pressure gradients, no leaks, and normal laminar flow. It should be easy to be implanted, silent, biocompatible, and resistant to thromboembolic problems. Lastly, it should be durable enough to last the patient’s lifetime. The disadvantages of a stent include an increase in stress forces associated with leaflet opening and closing, with possibility of leaflet abrasion adjacent to the cloth covering the stent.9.
Imaging modalities to assess the function and structure of the valve are several. Among those modalities is multi-detector computed tomography MDCT which identifies the leaflet thrombus as combined hypo attenuated leaflet together with reduced its mobility to 50% and more10
Moreover, the calcification with specific details regarding its distribution and density could be measured using CT to trace the possible increased calcification over years as one of Freestyle aortic valve complication.
As one of the steps of implanting the Freestyle aortic valve is manipulation of coronary artery ostia; both coronary ostia are mobilized on generous buttons of aortic wall, then the coronary arteries on their buttons of aortic wall are sewn end to side to the corresponding sinus of Valsalva of the bio prosthesis with a continuous 5–0 polypropylene suture11, that is why CT is important to evaluate the coronary ostia whether patent or stenotic.
Some reported that generally subclinical leaflet thrombosis occurred frequently in bioprosthetic aortic valves. And oral anticoagulants are prescribed for treatment and prevention of thrombosis.
David S. Bach et al., 200412 made a prospective study on 700 patients (93% >60 years of age) at 8 centers in North America having aortic valve replacement with the Freestyle stent-less bio prosthesis using the three methods of the implant technique. Follow-up was yearly till 8 years post operatively and they used clinical and echocardiographic study. They reported 100% freedom from structural valve deterioration using total root replacement. The effective orifice area was decreasing in 1 and 6 years post operative; however, with no significance (P=0.02). So, they conc-luded that the Freestyle stent less aortic root bio prosthesis is a versatile option for aortic valve replacement.
In the current study, Regarding calcification: we reported that the calcifi-cation over the leaflets was increasing over follow up periods, with calcification over the cusps: RCC ranging from (12-206), NCC (19-332), and LCC (4-44).
Regarding thrombus formation: we concluded that 22 cases out of 47 (46%) had positive thrombus formation. The thrombus had negative relationship with oral anticoagulants, and it had no association with size of Freestyle valve.
Jagdish Butany et al., 200713 Freestyle valves were reviewed to assess the reasons for bio prosthesis failure by using histochemistry and immunohistochemistry. Average implant duration was 52.8+-35.5 months. Four valves were explanted for infective endocarditis, three for aortic insufficiency, two for aortic stenosis with cusp calcification seen in five valves, pannus, and thrombus in all valves Although it was done in very small sample size, the duration of the valve implantation was short to develop the above-mentioned complication with thrombus in all valves. Adriaan W. Schneider 201914 they analyzed their experience with reinterventions after stent less AVR. A total of 75 patients with previous AVR using a Freestyle stent less bio prosthesis that underwent reinter-vention. In 47 (63%) patients, SVD was the failure mode of the stent less prosthesis. These patients typically presented with subacute dyspnea due to sudden increase of aortic regurgitation caused by leaflet tear or perforation. Non-SVD was the failure mode in 13(17%) patients and prosthesis endocarditis in 15(20%). | ||||
References | ||||
Conclusion
Although Freestyle aortic valve is a bioprosthetic valve, sub clinical thrombosis in it is a common complication and requires usage of oral anticoagulants. It has less durability with a need for redo surgery. MDCT is a valuable method for detection of structural valve deterioration. | ||||
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