Surgical Techniques
The heart is cannulated for cardiopulmonary bypass utilizing ascending aortic cannulation relatively high near the innominate artery and dual vena caval cannulas. Prior to aortic cross-clamping, the aorta and pulmonary artery are fully mobilized. There are usually adhesions from previous operations. After induction of cardioplegic arrest, a vertical aortotomy is performed, begun anteriorly and directed slightly to the left of the right coronary ostia Figure 36.1 . The aortotomy is retracted...
Surgical Technique Bst
Moderate to deep hypothermia is used in all cases with cannulation for bypass being achieved with an arterial cannula placed distally at the level of the innominate artery or beyond to permit wide mobilization of the ascending aorta. A single venous cannula in the atrial appendage is usually adequate. In most cases the procedure can be performed without a period of circulatory arrest other than for closure of the interatrial communication. Once on bypass, access to the left ventricular outflow...
Modified Root Replacement Concept Influence of Implant Technique on Allograft
Indications for the use of allografts for aortic valve replacement should be built upon an appreciation that this is non-viable collagen tissue, which will be subjected to a slow, variable but relentless immunological response, destined for eventual deterioration. Allograft durability and the performance characteristics which relate to durability depend upon several factors. These include donor age, procurement and preservation techniques, as well as immunogenicity. A primary issue, is that the...
Lloyd Wolfinbarger Jr Kelvin GM Brockbank and Richard A Hopkins
The intention of this chapter is to deal with the issues associated with the cryopreservation of heart valves and to review some of the approaches taken to resolve these issues. Cryo-preservation protocols have been developed empirically, based upon knowledge gained from the cryobiology of single-cell suspensions, and these protocols have consistently provided valves that perform adequately for extended periods of time.1 It now becomes important to find out why cryopreserved allogeneic valves...
Reduction Aortoplasty
Barratt-Boyes5 and Ross and associates6 have emphasized the role of aortic root reduction, or tailoring, to reduce the size of the aortic root. One of the major reasons cited for failure in Barratt-Boyes' 1987 review was dilated aortic root. His group advised against placement of an allograft in a root larger than 30 mm in diameter, although they did recommend placement if the aortic root could be tailored to a diameter Figure 34.1. Effect of splaying and convergence of ation of the allograft...
Richard A Hopkins and Gary K Lofland
Homograft tissue can be used in creative ways to reconstruct systemic outflow by dedicating the pulmonary valve to the systemic ventricle, using nonvalved homograft tissue to augment the neo-LVOT outflow, and re-establishing with a second homograft, pulmonary ventricle to pulmonary continuity, or in the case of single ventricle, performing a variation on the Norwood operation. Double Outlet Right Ventricle with Transposition of the Great Arteries and Hypoplastic Aorta with Either Interrupted...
Sizing of Aortic Root for Allograft Insertion
Careful matching of allograft size to aortic annulus is important for optimal performance. It requires a slightly different set of assumptions for the surgeon accustomed to using rigid stented prostheses, as the measured diameter of the allograft is the internal diameter in contrast to the external diameter for standard prostheses and thus allowance must be made for wall thickness. In addition, the hemodynamic performance of the smaller allograft aortic valves is markedly superior to mechanical...
Coronary Ostia Arising High in the Sinuses
In the case of the coronary ostia arising high in the sinuses, the problem for the surgeons is simplified. Resection of the allograft coronary sinus can be minimized, and the proximal suture line placed conveniently at the bottom of the sinus at the level of the native leaflet attachment Figure 34.16 . The distal suture line is comfortably created around the coronary orifice. Note that the proximal suture line does not follow the semilunar cusp attachment superiorly but, rather, crosses the...
Cellular Components
Four major types of cells are present in cardiac valves 1 endothelial cells 2 interstitial connective cells 3 mononuclear cells derived from the blood, and 4 interstitial dendritic cells. The endothelial cells form a continuous monolayer that completely lines the surfaces of the valves and is contiguous with the endothelial cell layer of adjacent regions of the endocardium and or great vessels. These cells are flattened, have single, centrally located nuclei, contain actin-like and intermediate...
The Use of Homograft Valves Historical Perspective
In 1956 Gordon Murray reported the use of fresh aortic valve homografts transplanted into the descending thoracic aorta for amelioration of the consequences of native aortic valve insufficiency. His initial operations preceded by 5 years the availability of the Starr-Edwards mechanical aortic valve prosthesis.1-7 Although this operation was only partially successful hemodynamically, the homograft valves had remarkable durability and performance. Four patients cited by Heimbecker had no...
Aortic and Pulmonary Valves
The hemodynamic performance of the aortic valve is determined by the dynamics of the aortic root, the pattern of cuspal closure in response to small changes in pressure, and the sharing of mechanical and dynamic stresses between the cusps and the sinuses of Valsalva. Stresses within the valvular tissue result from the presence of a pressure gradient across the cusps when the valve is closed and from the reversal of the cuspal curvature as the valve responds to changes in pressure and flow...
Evaluation of Pulmonary Autograft Function
Following transplantation of the pulmonary autograft, TEE evaluation of the autograft function is critical to assess immediate surgical adequacy and predict the long-term results. In their retrospective series of 145 Ross operations Stelzer et al.1 noted the consistent absence of any significant pressure gradient across the autograft on early and late follow-up echocar-diographic examination. In this series and others, a tiny central jet of aortic regurgitation AR is commonly seen. Mild...
Anatomy of the Right Ventricular Outflow Tract
Before describing variations in coronary arterial anatomy, it is imperative to have a clear understanding of the anatomy of the pulmonary valve, specifically of the components of the pulmonary infundibulum Figure 40.1 . Excellent work in this area was published many years ago,2'3 and will be amplified here. The pulmonary valve is, in most cases, a trileaflet valve supported by a muscular infundibulum. The infundibulum has two com ponents, a free-standing component existing in a plane superior...
Pulmonary Valve Orthotopic Implants Patients
Among the 140 patients receiving an orthotopic pulmonary valve without a conduit, only the size of the valve had a statistically important effect upon the interval free of valve reoperation. Valve size is an important determinant of valve durability for all types of prosthetic pulmonary valves Figure 7.5 . Figure 7.4. There is a greater chance of being free of pulmonary valve reoperation with an orthotopic implant PVI, n 140 at operation than with a valved conduit n 354 at operation, p lt 0.01...
Richard A Hopkins Qnu
Stentless porcine heterografts for aortic valve replacement are now commercially available. Three such valves have now been approved by the FDA for use in humans. One is a scalloped valve designed for a standard subcoronary insertion Toronto SPV Valve, St. Jude Medical, St. Paul, MN and two others Medtronic Freestyle and Edwards Prima Plus are prepared as a root and can be trimmed for insertion as either a miniroot, root or subcoronary scalloped technique. All three valves are glutaraldehyde...
Donor Suitability
Permission for heart donation is usually obtained in writing or via a taped, documented telephone conversation with the donor's legal next of kin, even if a potential donor carries an organ donor card. Alternatively, a self-signed donor document can be accepted as long as it is in accordance with the Uniform Anatomical Gift Act and applicable state and local regulations. Once permission is obtained, the donor must be adequately screened to minimize any potential transfer of an infectious...
Surgical Technique for Standard Aortic Root Replacement
As Ross originally devised, we use an interrupted proximal suture line technique.45 The aortic root is excised and the native coronary ostia left on large buttons of aortic tissue Figures 35.1, 35.2, and 35.3 . An additional septal myomectomy is performed if necessary Figure 35.4 . The allograft is then oriented in the orthotopic position, with the left coronary ostia comfortably positioned toward the button of the native left coronary ostia. The proximal suture line is constructed of a series...
Stephen L Hilbert Frederick J Schoen and Victor J Ferrans
Pulmonary and aortic valves transplanted from one human to another referred to as homo-grafts or allografts have been used for valvular replacement and ventricular outflow tract reconstruction for approximately 40 years.1-5 Predominantly derived from cadaver donors, allograft valves may also be taken from hearts in which the aortic valve is explanted intact at cardiac transplantation. The objective of this chapter is to review the morphological features, functional relationships and explant...
Sterilization and Disinfection 1
In order to provide a disinfected allograft for transplantation, identification and elimination of any potential contaminants are required. AATB Standards dictate that processing shall include an antibiotic disinfection period followed by rinsing, packaging, and cryopreserva- tion, and that disinfection of cardiovascular tissue shall be accomplished via a validated, time specific antibiotic incubation. Disinfection involving incubation of the allograft in low-concentration, broad-spectrum...
Thawing and Dilution Prior to Surgical Preparation of the Allograft
Preparing the frozen allograft for transplantation involves thawing the tissue at a specific rate, diluting the cryoprotective agents, and restoring the cryopreserved tissue to osmotic isotonicity. Careful handling of the allograft and strict adherence to protocols are imperative. To maximize cellular viability and matrix structure, heart valve leaflet manipulation should be kept to a minimum. After thawing and dilution, the recovering heart valve should be kept moist and bathed in a...
Heart Valve Evaluation and Examination
The AATB Standards mandate a standardized evaluation and classification system for allo-graft heart valves. This evaluation should include sizing and a qualitative graft assessment. A system must be in place to notify the implanting surgeon of any graft's condition if requested prior to final dispensing. Sizing the allograft is a vital aspect of the processing procedures consistency and accuracy are of the utmost importance. Incorrect sizing of the allograft aortic root diameter could require...
Homograft Preservation
The original technique of homograft preservation in nutrient antibiotic solution produced excellent results as reported by Kay and Ross21 and Tam.22 In our series, cryopreserved homo-grafts performed somewhat worse than those preserved in antibiotic nutrient solution but the difference could be accounted for by association with recent patient number and with earlier reintervention in recent years. We therefore feel that the use of both cryopre-served homografts and homografts preserved in...
Anatomy
The essential defect in transposition is discordant connection between the ventricles and the great vessels. In the subgroup that includes left ventricular outflow tract obstruction LVOTO , usually there is an associated ventricular septal defect, which can vary in size but is most frequently adjacent to the pulmonary valve. With an outlet type ventricular septal defect, the nature of the LVOTO is usually due to posterior deviation of the outlet septal defect, the mature of the LVOTO is usually...
Surgical Technique for Scalloped Subcoronary Insertion
The scalloping of the valve is either accomplished by the manufacturer or can be performed by the surgeon prior to or after the proximal suture line has been accomplished. Aortotomy is performed in one of two ways depending upon whether the ascending aorta at the level of the sinus ridge is of the diameter desired at the conclusion of the repair or is enlarged. A transverse aortotomy is performed above the level of the sinus ridge if the sinus ridge anatomy appears appropriate where as a Lazy S...
Incidence of Aortic Insufficiency After the Ross Procedure
The incidence of aortic insufficiency after the Ross procedure is not well known, primarily due to the limited amount of published experience in this regard. Of course, the initial expe rience with this technique was that of Mr. Ross himself. Long-term follow-up of Ross' experience was reported in 1991 and included 339 patients beginning with his first patient in 1967.1 The mean follow-up was 11.8 years and maximum follow up was 24 years. In that entire group of patients, the number of patients...
Extracellular Matrix 1
Cardiac valves are primarily composed of extracellular matrix components of connective Figure 22.5. Transmission electron micrograph demonstrating the loss of collagen crimp, as shown by collagen fibril elongation or straightening. High pressure-fixed porcine aortic valve. x 2,900. Figure 22.5. Transmission electron micrograph demonstrating the loss of collagen crimp, as shown by collagen fibril elongation or straightening. High pressure-fixed porcine aortic valve. x 2,900. Figure 22.6....
Franciska Hoekstra Christiaan Knoop Ad Bogers and Willem Weimar
The antigenicity of valve allografts has been a matter of debate since their introduction for clinical use. Fresh and cryopreserved valve allo-grafts have classically been regarded as tissues with low antigenicity. Indeed, long-term follow-up studies after implantation of cryopreserved valves showed good clinical results, especially in adults.12 Nevertheless, valve allograft deterioration, resulting from an intrinsic abnormality structural valve damage is frequently seen, although these...
Aortic Root Replacement with Stentless Porcine Heterografts
For complex aortic root anatomy or for infected aortic roots, it is sometimes preferable to completely replace the entire aortic root rather than using a miniroot or subcoronary scallop technique. In this case, the operation is very similar to that described for the aortic root replacement with a homograft. Sizing is accomplished utilizing either Hegar dilators or sizers provided by the companies. Only the intact aortic root heterograft prosthe ses are suitable for this technique. The size of...
V Mohan Reddy Doff B McElhinney and Frank L Hanley
Pulmonary autograft aortic valve replacement the Ross procedure is increasingly being considered for application in pediatric patients with a wide spectrum of congenital abnormalities of the left ventricular outflow tract.1-6 However, the establishment of this procedure increases our therapeutic choices for many pediatric patients with complex left ventricular outflow tract obstruction, thereby forcing us to re-evaluate more traditional treatment protocols for a number of patient subsets.6-9...
Robert H Messier Jr Diane HoffmanKim and Richard A Hopkins
Cardiac valve leaflet interstitial cells LIC provide the essential synthetic means of continuous matrix production and remodeling within the valve and possess contractile functions that likely contribute to the valve's enormous capacity for endurance. In light of their importance, the present chapter focuses on these cells' capacity to maintain a viable, functional population, both in culture and after typical post-harvest processing. Two studies have looked at the responses of LIC to isolation...
Cryoprotectant Removal
After thawing cryopreserved tissues, current opinion is that the cryoprotective agents must be removed. Although the mechanism for DMSO toxicity has not been determined, its ability to affect membrane fluidity,126 induce cell differen-tiation127 and modify cell structure by induction of changes in cytoplasmic microtubules has been well documented.128129 DMSO also forms stable coordination complexes with metals.107 Cryoprotective agents are generally removed by a stepwise dilution procedure....
Cooling Protocol
An average adult heart valve to be cryopre-served is typically 6 cm in length from the annulus to the distal aspect of the aortic conduit. The valves are sized based on internal diameter and the average thickness of the aortic wall is approximately 1.6 mm. Valves are usually frozen in a total volume of 100 ml and the valve typically constitute 7-15 of the total volume to be frozen. Several considerations must be taken into account in the cryogenic preservation of biological tissues. The rate of...
David C McGiffin and James K Kirklin
Infective endocarditis, both native and prosthetic, is ultimately a fatal illness without therapy, reflecting the inability of innate defenses to importantly influence the course of the disease. Following the diagnosis, the therapy of this illness depends on identification of the organism, administration of bactericidal antibiotics and the use of timely cardiac surgical intervention in patients with complications such as heart failure from valvular destruction, annular abscess formation,...
Heart Procurement
The time period from cessation of heartbeat until cardiac procurement as the warm ischemic time and the time interval from placement of tissue in cold transport solution to the beginning of disinfection as the cold ischemic time. The AATB Standards permit cardiovascular tissue recovery to be established by each individual bank however the following upper time limits for completion of retrieval and processing of cardiovascular tissues may not be exceeded 1. Warm ischemic time shall not exceed 24...
Conclusion The Leaflet Interstitial Cell as Myofibroblast
Table 13.1 provides a summary of the pheno-typic characteristics of LIC, as demonstrated by the work of our group and others. The results of these studies together indicate that the cardiac valve LIC can be designated a myofi-broblast, that is, a cell that possesses properties of both connective tissue fibroblasts and smooth muscle cells. LIC are not alone in this designation. In other tissues, interstitial cells that resemble fibroblasts have also been found to have contractile properties.1516...
Manouguian Technique
The method described by Manouguian and Seybold-Epting for prosthetic valve placement and enlargement utilizing a pericardial patch sutured into the anterior leaflet of the native mitral valve can be adapted to a technique applicable to freehand allograft insertion.3 The aortotomy is extended somewhat more posteriorly than usual through the region of the native commissure above the midpoint of the anterior leaflet of the mitral valve Figure 33.1 . The depth of the incision into the left atrium...
MG Hazekamp DR Koolbergen J Braun JA Bruin CJ Cornelisse YA Goffin and JA
Efforts in preservation of allograft heart valves aim at remaining cellular viability. Viability in this respect always means fibroblast viability as endothelial cells are almost completely lost in the sequence of dissection, sterilization, cryopreservation, thawing and implantation.1'2 Cryopreservation is now considered to be the method of choice of allograft heart valve preservation and banking. Cellular viability after cryopreservation has been well documented.3-5 The length of donor...
Allograft Valves and Other Replacement Heart Valves
The first clinical implantation of a mechanical replacement heart valve was performed in 1958 using a ball-in-cage valve inserted in the descending thoracic aorta.6 The first orthotopic valve replacements were accomplished in 1960 aortic position 7 and 1961 mitral position .8 Mechanical heart valve designs continued to evolve, with the current prosthetic designs consisting of ball-in-cage, tilting disk and bileaflet valves. The occurrence of thromboembolic events and of sudden, life-threatening...
Contributors
Clinical Associate Professor of Surgery, University of South Florida, Tampa, FL, USA Department of Surgery and Pediatrics, University of Alberta, Alberta, Canada Professor of Surgery, University of Louisville, and Chief, Cardiovascular Surgery, Kosair Children's Hospital, Louisville, KY, USA Director of Cardiothoracic Anesthesia, Rhode Island Hospital, and Clinical Associate Professor of Anesthesiology, Brown University School of Medicine, Providence, RI, USA Research Associate, Pediatric...