Full-root Aortic Valve Replacement by Stentless Aortic Xenografts in Patients with Small Aortic Roots

Summary

Full-root aortic valve replacement by stentless aortic xenograft is a viable option in patients with small aortic roots. We describe, a technique for the full-root implantation of stentless aortic xenografts, with emphasis on the management of the proximal suture line and coronary anastomoses, and discuss its limitations and alternative options.

Abstract

In patients with small aortic roots who need an aortic valve replacement with biological valve substitutes, the implantation of the stented pericardial valve might not meet the functional needs. The implantation of a too-small stented pericardial valve, leading to an effective orifice area indexed to a body surface area less than 0.85 cm²/m², is regarded as prosthesis-patient mismatch (PPM). A PPM negatively affects the regression of left ventricular hypertrophy and thus the normalization of left ventricular function and the alleviation of symptoms. Persistent left ventricular hypertrophy is associated with an increased risk of arrhythmias and sudden cardiac death. In the case of predictable PPM, there are three options: 1) accept the PPM resulting from the implantation of a stented pericardial valve when comorbidities of the patient forbid the more technically demanding operative technique of implanting a larger prosthesis, 2) enlarge the aortic root to accommodate a larger stented valve substitute, or 3) implant a stentless biological valve or a homograft. Compared to classical aortic valve replacement with stented pericardial valves, the full-root implantation of stentless aortic xenografts offers the possibility of implanting a 3-4 mm larger valve in a given patient, thus allowing significant reduction in transvalvular gradients. However, a number of cardiac surgeons are reluctant to transform a classical aortic valve replacement with stented pericardial valves into the more technically challenging full-root implantation of stentless aortic xenografts. Given the potential hemodynamic advantages of stentless aortic xenografts, we have adopted full-root implantation to avoid PPM in patients with small aortic roots necessitating an aortic valve replacement. Here, we describe in detail a technique for the full-root implantation of stentless aortic xenografts, with emphasis on the management of the proximal suture line and coronary anastomoses. Limitations of this technique and alternative options are discussed.

Introduction

Biological aortic valve replacement is recommended for patients older than 65 years¹. In patients with small aortic roots, the implantation of a stented biological valve substitute based on the labelled size given by the manufacturer might not meet the functional needs. In this situation, Rahimtoola first described the prosthesis-patient mismatch (PPM) as follows: "mismatch can be considered to be present when the effective prosthetic valve area, after insertion into the patient, is less than that of a normal human valve"². The effective orifice area of the valve prosthesis is to be related to the patien....

Protocol

The protocol follows the institutional guidelines of the human research ethics committee.

1. Pre-selection of the Patient

1. Using the preoperative echocardiography, identify patients with an estimated aortic annulus diameter of less than 20 mm. Be aware that in heavily calcified aortic valves and annuli, the preoperative echocardiography can sometimes be misleading.
2. Select from these patients a subgroup with a body surface area greater than 1.6 m².
3. Verify on the chart provided by the valve manufacturer that a stented pericardial aortic valve substitute labelled 19 mm has an effective orifice area of ....

Results

Statistical analysis

The values of projected effective orifice area indexed to the body surface area (EOAI, cm²/m²) for implanted stentless aortic xenografts sized 23 mm are expressed as means ± SD and compared to the calculated EOAI of stented pericardial valves 4 mm smaller (i.e., 19 mm) using the non-parametric Mann Whitney test. In Table 2, continuous variables are compared using the non-parametri.......

Discussion

This study reports a detailed description of the surgical technique of full-root aortic valve replacement using stentless aortic xenografts in patients with small aortic roots. Early morbidity and mortality are very low and compare favorably with other reports⁷. Heavily calcified coronary ostia constitute an anatomical limitation to this technique. Another drawback to this technique is represented by patients with a poor general condition who would not tolerate longer operative times. In these cas.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Heart surgery infrastructure:
Heart Lung Machine	Stockert	SIII
EOPA 24Fr. arterial cannula	Medtronic	77624
Atrial caval venous cannula 34/48Fr.	Medtronic	93448
LV vent catheter 17Fr.	Edwards	E061
Antegrade 9Fr. cardioplegia cannula	Edwards	AR012V
Retrograde 14Fr. cardioplegia cannula	Edwards	NPC014
Coronary artery ostial cannula 90°	Medtronic	30155
Coronary artery ostial cannula 45°	Medtronic	30255
Name	Company	Catalog Number	Comments
Valve subsitutes:
Stentless aortic xenograft Prima Plus 23 mm	Edwards	2500P-23	anti-calcification XenoLogiX treatment
Stentless aortic xenograft Sizer 23 mm	Edwards	1170
Stentless aortic xenograft Freestyle 23 mm	Medtronic	FR995-23	alpha amino oleic acid (AOA) anti-calcification treatment
Stentless aortic xenograft Sizer 23 mm	Medtronic	7900
Electrocautery	Covidien	Force FXTM
Name	Company	Catalog Number	Comments
Sutures:
Polypropylene 4/0	Ethicon	8871H
Polypropylene 5/0	Ethicon	8870H
Polypropylene 6/0	Ethicon	EH7400H
Braided polyesther 2/0 ligature with polybutylate coating	Ethicon	X305H
Micro knife Sharpoint	TYCO Healthcare PTY	78-6900
Name	Company	Catalog Number	Comments
Drugs:
Midazolam	Roche Pharma	N05CD08
Rocuronium	MSD Merck Sharp & Dohme	M03AC09
Propofol	Fresenius Kabi	N01AX10
Fentanil	Actavis	N01AH01
Heparin	Braun	B01AB01
Protamin	MEDA Pharmaceutical	V03AB14
Name	Company	Catalog Number	Comments
Instruments:
Cooley vascular aortic clamp	Delacroix-Chevalier	DC40810-16
Dissection forceps Carpentier	Delacroix-Chevalier	DC13110-28
Scissors Metzenbaum	Delacroix-Chevalier	B351751
Needle holder Ryder	Delacroix-Chevalier	DC51130-20
Dissection forceps DeBakey	Delacroix-Chevalier	DC12000-21
Micro needle holder Jacobson	Delacroix-Chevalier	DC50002-21
Micro scisors Jacobson	Delacroix-Chevalier	DC20057-21
Lung retractor	Delacroix-Chevalier	B803990
Allis clamp	Delacroix-Chevalier	DC45907-25
O’Shaugnessy Dissector	Delacroix-Chevalier	B60650
18 blade knife	Delacroix-Chevalier	B130180
Leriche haemostatic clamp	Delacroix-Chevalier	B86555
Name	Company	Catalog Number	Comments
Data analysis:
Mann-Whitney and Chi-square tests	GraphPad	Prism 7