Aortic valve sparing operations: a review

[Long-term result of aortic root remodeling using the Florida sleeve technique in a patient with connective tissue dysplasia and aortic root aneurysm without aortic insufficiency]

Aortic root remodeling using the Florida sleeve technique was proposed as a simpler alternative to classical reconstructive interventions in patients with aortic root aneurysm without aortic insufficiency. We present a 10-year result of valve-sparing surgical treatment using the Florida sleeve technique in a patient with connective tissue dysplasia and aortic root aneurysm.

[Operation in DeBakey type I acute aortic dissection according to the Florida Sleeve technique]

Despite the fact that recent decades have witnessed significant advances in treatment of patients with DeBakey type I acute aortic dissection, it still remains difficult to restore the aortic root when the dissection extends to the Valsalva's sinuses. Thinned aortic walls are vulnerable to traumatization on applying a vascular suture. We used in patients with this pathology the Florida sleeve technique in order to reinforce the weakened aortic root. After mobilization of the aortic root and coronary arteries, the transplant 'wraps' the sinuses from the outside, like the neoadventitia, in order to strengthen the weakened aortic wall. The graft's diameter should be selected with due regard for tight enwrapment of coronary sinuses in their maximal dilatation and, if necessary, preserving the possibility of narrowing the fibrous ring. This technique is simple and effective. First, it allows strengthening the weakened root, secondly helping to prevent haemorrhage. Besides, it may prove alternative, should preservation or correction of the geometry of the aortic root be required.

The importance of collagen composition and biomechanics for the porcine aortic root

A thorough understanding of the aortic root structure and biomechanics is necessary when performing aortic valve-sparing procedures in patients with aortic root aneurysms. This study aimed to evaluate the amount of collagen and biomechanics at different levels and segments of the aortic root. Ten aortic roots from healthy pigs were excised including the aortic annulus, the sinuses of Valsalva, and the sinotubular junction (STJ). Specimens were further divided into three circumferential segments; left coronary (LC)-, right coronary (RC)-, and non-coronary (NC) sinus. Collagen was determined using hydroxyproline analysis and specimens were tested biomechanically for stress-strain relations. The annulus showed significantly larger average maximum stiffness (9.6 ± 4.5 N/mm) compared with the sinus (4.5 ± 2.0 N/mm) and STJ (4.8 ± 1.8 N/mm). The average collagen content was likewise higher in the annulus (4.0 ± 1.0 mg/ml) compared with the sinus (2.4 ± 0.6 mg/ml) and STJ (2.2 ± 0.5 mg/ml) for all three segments. The NC sinus segment exhibited a significantly larger maximum stiffness and stress under static conditions compared with the RC. These results suggest that the aortic root is heterogeneous in both structure and biomechanical properties and that it varies both in levels and segments of the aortic root. Future surgical approaches should consider enhanced strength parameters for specific areas of the aortic root to achieve the best results when performing aortic valve-sparing techniques. From this study, we conclude that the aortic annulus needs special attention to imitate normal physiologic properties during aortic valve-sparing surgery due to its higher maximum stiffness, stress, and load. Modified future surgical procedures could potentially prevent recurrent aneurysmal formation.

Management of the aortic root in type A aortic dissection: A valve sparing approach

BACKGROUND

Type A acute aortic dissection (TAAAD) is rapidly fatal without emergency repair. Surgical outcomes have improved over the years with improvements in technique and postoperative care. Classically, supracomissural aortic replacement has been the standard of care. However, reintervention rates, particularly on the aortic root in certain groups of patients, shifted the focus towards improving long-term results of surgical repair. With regard to the aortic root, root replacement has been the gold standard. However, the surgical community realized that valve replacement in itself is a disease, and valve sparing aortic root replacement (VSRR) took center stage in the care of these patients.

METHODS

We searched the Pubmed and EMBASE databases for articles related to VSRR and composite valve conduit (CVC) root replacement, and the long-term results of these techniques in TAAAD.

RESULTS

Supracomissural repair is limited by reintervention, and CVC results are affected by complications related to the prosthetic valve. Conversely, VSRR is associated with good short-term outcomes, improvement in quality of life, and it is durable.

CONCLUSION

VSRR is a sound technique in TAAAD in experienced hands.

Outcomes of Florida Sleeve Procedure in Patients with Bicuspid Versus Tricuspid Aortic Valve

OBJECTIVE

Outcomes of the Florida Sleeve (FS) procedure in patients with bicuspid aortic valve (BAV) have not been reported before. We compared outcomes of the FS procedure between patients with BAV and those with tricuspid aortic valve (TAV).

METHODS

From May 1, 2002 to January 1, 2016, 177 patients including 18 BAV and 159 TAV underwent the FS procedure. Baseline characteristics, perioperative outcomes, and echocardiographic measurements were compared between the 2 groups. Kaplan-Meier and life-table analyses were used to evaluate survival and freedom from reintervention rates.

RESULTS

Mean ± standard deviation age and aortic root diameter were comparable in BAV and TAV groups, 47.83 ± 11.19 versus 49.59 ± 15.79 years (P = 0.55) and 56.57 ± 6.18 versus 55.17 ± 8.84 mm (P = 0.46), respectively. The 30-day mortality and stroke rates were zero in the BAV group and 1.88% (n = 3) in the TAV group (P = 1.00). One patient (5.55%) in the BAV group and 8 (5.03%) patients in the TAV group needed permanent pacemaker implantation (P = 0.62). Freedom from reoperation was 93% in the BAV group and 99% in the TAV group at 8 years (P = 0.041). Patient survival rate was 100% in the BAV group and 91% in the TAV group at 8 years (P = 0.42). Freedom from aortic insufficiency greater than mild was 93% in the BAV group and 96.5% in the TAV group at 5 years (P = 0.61).

CONCLUSIONS

This is the first study reporting outcomes of the FS procedure in patients with BAV. This technique is feasible, and the results appear to be durable when compared to patients with TAV.

Modified Sleeve Technique in Aortic Valve-Sparing Operation for Marfan Syndrome

We devised a simple modification of the Florida Sleeve procedure to perform aortic valve-sparing surgery. This technique is simple, quick, effective, and safe. We used this technique in operations performed on two young patients with Marfan syndrome. The initial and short-term results were satisfactory.

Simplified surgical approach to improve surgical outcomes in the center with a small volume of acute type A aortic dissection surgery

BACKGROUND:

Despite recent advances in surgical techniques and perioperative management, the surgical mortality of acute type A aortic dissection remains high.

OBJECTIVE:

In a hospital with few acute type A aortic dissection operations, we retrospectively investigated whether simplified surgical approach could obtain proper surgical outcomes.

METHODS:

Between October 2007 and December 2016, we performed emergency surgery in 99 patients who had acute type A aortic dissection, including replacement of the hemi-arch in 62 patients (63%) and total arch in 32 patients (32%) and aortic root surgery in 7 patients (7%). Surgical strategy has been simplified over time.

RESULTS:

We performed right axillary artery perfusion in 61 patients (62%) and antegrade cerebral perfusion in 78 patients (79%). During the last 3 years, in-hospital mortality was decreased to 4% (2/47). Preoperative unresolved shock was an independent predictor of hospital death. Although the patients with total arch replacement or aortic root surgery had a mean significantly long cardiopulmonary bypass or circulatory arrest time, in-hospital mortality or neurologic complications was not increased.

CONCLUSIONS:

Simplified surgical approach could provide a reasonable surgical outcome in acute type A aortic dissection surgery in a center with a small volume of acute aortic dissection surgery.

Biomechanical characterization and comparison of different aortic root surgical techniques

OBJECTIVES

Understanding the biomechanical impact of aortic valve-sparing techniques is important in an era in which surgical techniques are developing and are increasingly being used based on biomechanical understanding that is essential in the refining of existing techniques. The objective of this study was to describe how the valve-sparing remodelling (Yacoub) and reimplantation (David Type-1) techniques affect the biomechanics of the native aortic root in terms of force distribution and geometrical changes.

METHODS

Two force transducers were implanted into 22 pigs, randomized to 1 of 3 groups (David = 7, native = 7 and Yacoub = 8) along with 11 sonomicrometry crystals and 2 pressure catheters. Force and geometry data were combined to obtain the local structural stiffness in different segments of the aortic root.

RESULTS

The radial structural stiffness was not different between groups (P = 0.064) at the annular level; however, the David technique seemed to stabilize the aortic annulus more than the Yacoub technique. In the sinotubular junction, the native group was more compliant (P = 0.036) with the right-left coronary segment than the intervention groups. Overall, the native aortic root appeared to be more dynamic at both the annular level and the sinotubular junction than both intervention groups.

CONCLUSIONS

In conclusion, the David procedure may stabilize the aortic annulus more than the Yacoub procedure, whereas the leaflet opening area was larger in the latter (P = 0.030). No difference (P = 0.309) was found in valve-opening delay between groups. The 2 interventions show similar characteristics at the sinotubular junction, whereas the David technique seemed more restrictive at the annular level than the Yacoub technique.

A framework for designing patient-specific bioprosthetic heart valves using immersogeometric fluid-structure interaction analysis

Numerous studies have suggested that medical image derived computational mechanics models could be developed to reduce mortality and morbidity due to cardiovascular diseases by allowing for patient-specific surgical planning and customized medical device design. In this work, we present a novel framework for designing prosthetic heart valves using a parametric design platform and immersogeometric fluid-structure interaction (FSI) analysis. We parameterize the leaflet geometry using several key design parameters. This allows for generating various perturbations of the leaflet design for the patient-specific aortic root reconstructed from the medical image data. Each design is analyzed using our hybrid arbitrary Lagrangian-Eulerian/immersogeometric FSI methodology, which allows us to efficiently simulate the coupling of the deforming aortic root, the parametrically designed prosthetic valves, and the surrounding blood flow under physiological conditions. A parametric study is performed to investigate the influence of the geometry on heart valve performance, indicated by the effective orifice area and the coaptation area. Finally, the FSI simulation result of a design that balances effective orifice area and coaptation area reasonably well is compared with patient-specific phase contrast magnetic resonance imaging data to demonstrate the qualitative similarity of the flow patterns in the ascending aorta.

Biomechanical assessment of the aortic root using novel force transducers

In recent years the use of valve sparing techniques has become more common in selected patients with aortic valve insufficiency. However, limited experimental research has been performed to document the biomechanical effect of these techniques. One experimental platform is to evaluate how the normal physiological aortic root forces are altered or re-established after the surgical intervention. Hence, the aim of this project was to develop new implantable force transducers for a biomechanical description of various aortic root repair techniques. Two novel force transducers were developed. Both transducers were manufactured using rapid prototyping and were instrumented with miniature strain gauges. Before implantation both transducers were calibrated using a dedicated setup, yielding very linear correlation between the applied load and transducer output. The developed force transducers were implanted and tested in an 80kg porcine model. In the post-cardioplegic heart, the peak annular forces varied in the range of 2-4N and the commissural forces varied from 0.4 to 0.8N with a left ventricular pressure of 111mmHg. In conclusion, the two new force transducers to measure forces in the aortic root have successfully been developed. With these new devices a novel versatile and direct force measurement system has been provided.

Old Myths, New Concerns: the Long-Term Effects of Ascending Aorta Replacement with Dacron Grafts. Not All That Glitters Is Gold

Synthetic grafts are widely used in cardiac and vascular surgery since the mid-1970s. Despite their general good performance, inability of mimicking the elastomechanical characteristics of the native arterial tissue, and the consequent lack of adequate compliance, leads to a cascade of hemodynamic and biological alterations deeply affecting cardiovascular homeostasis. Those concerns have been reconsidered in more contemporaneous surgical and experimental reports which also triggered some research efforts in the tissue engineering field towards the realization of biomimetic arterial surrogates. The present review focuses on the significance of the “compliance mismatch” phenomenon occurring after aortic root or ascending aorta replacement with prosthetic grafts and discusses the clinical reflexes of this state of tissue incompatibility, as the loss of the native elastomechanical properties of the aorta can translate into detrimental effects on the normal efficiency of the aortic root complex with impact in the long-term results of patients undergoing aortic replacement.

A Simple Device for Morphofunctional Evaluation During Aortic Valve-Sparing Surgery

Valve-sparing operations for the treatment of aortic root disease with a structurally normal aortic valve are increasingly performed as they avoid prosthesis-related complications. Short- and long-term results are critically dependent on perfect intraoperative restoration of valve anatomy and function. Residual aortic regurgitation is the main cause of early failure, and it is the most common motive for reoperation. However, intraoperative morphofunctional valve assessment requires expertise, and only transesophageal echocardiography can provide reliable information. We describe a simple, economic, reproducible hydrostatic test to intraoperatively evaluate valve competency under direct visualization.

Florida sleeve repair for aortic root aneurysm

A 74-year-old man was diagnosed with aortic root aneurysm and two-vessel coronary disease. Echocardiographic assessment revealed an enlarged sinus of Valsalva 60 mm in diameter with mild aortic regurgitation. Florida sleeve repair was performed using a vascular graft combined with coronary artery bypass grafting. The postoperative course was uncomplicated and follow-up echocardiographic evaluations showed an aortic root diameter of 38 mm without aortic insufficiency up to 1 year after surgery.

A modified root reinforcement technique for acute aortic dissection with a weakened aortic root: a modified Florida sleeve technique and two cases report

Despite marvelous advances in repair for acute type A aortic dissection over past decades, it remains challenging to repair the aortic root when aortic dissection extended to the sinuses causes the fragile root because of its thinner layers, which are susceptible to suture trauma. Here, we describe a modified Florida sleeve technique to strengthen the weakened aortic root. After mobilization of the aortic root and the coronary arteries, a designed Dacron tube graft was wrapped outside the sinuses as neo-adventitia to reinforce the dissected weakened wall. During surgery for aortic dissection, our technique is easy and effective to reinforce a weakened root and avoid bleeding. Furthermore, this might be an alternative technique to restore and maintain the geometry of the aortic root.

Surgical Approaches to Aortic Valve Replacement and Repair-Insights and Challenges

Since 1960, surgical aortic valve replacement (sAVR) had been the only effective treatment for symptomatic severe aortic stenosis until the recent development of transcatheter aortic valve replacement (TAVR). TAVR has offered an alternative, minimally invasive treatment approach particularly for patients whose age or co-morbidities make them unsuitable for sAVR. The rapid and enthusiastic utilization of this new technique has triggered some speculation about the imminent demise of sAVR. We believe that despite the recent advances in TAVR, surgical approach to aortic valve replacement has continued to develop and will continue to be highly relevant in the future. This article will discuss the recent developments and current approaches for sAVR, and how these approaches will keep pace with catheter-based technologies.