Heart-valve homograft

A heart-valve homograft is a human heart valve, typically the aortic or pulmonary valve, that is recovered from a deceased human donor, processed and cryopreserved, and later surgically implanted into a patient to replace a diseased native or prosthetic valve. In this context the term homograft is synonymous with allograft: both denote tissue transplanted between genetically non-identical members of the same species (here, human to human), as distinguished from a xenograft (tissue of animal origin) or an autograft (the patient's own tissue).[1][2] Heart-valve homografts are valued for their natural anatomy, favorable blood-flow characteristics, and resistance to infection, and they are used most prominently in aortic and pulmonary valve replacement, in surgery for infective endocarditis, in congenital heart disease, and as part of the Ross procedure.[2][3][4]

Terminology

A homograft (allograft) heart valve is harvested from a human cadaveric or brain-dead donor.[2] The first successful human implantations were performed in 1962, and antibiotic sterilization and cryopreservation methods that define the modern allograft were introduced in the late 1960s and 1970s.[5][6] Because the valve is human tissue rather than a manufactured device or animal-derived prosthesis, it is regulated in the United States as a human cell, tissue, or cellular and tissue-based product (HCT/P), not as a transplanted organ.[7][8] (See also FDA regulation of human tissue (HCT/Ps).)

Clinical uses

Aortic valve replacement Aortic valve replacement with an aortic homograft is a well-established procedure characterized by low transvalvular gradients, a low risk of thromboembolic events, high resistance to endocarditis, and acceptable long-term results compared with other bioprosthetic and mechanical valves.[2] Homografts are often selected for younger patients, for patients who wish to avoid lifelong anticoagulation, for women who may become pregnant, and for anatomically small aortic annuli where the stentless design preserves effective orifice area.[1][4]

Infective endocarditis and infected fields The strongest contemporary indication for the aortic homograft is infective endocarditis, particularly prosthetic-valve endocarditis with periannular abscess or aortic-root destruction.[9][2] Homograft aortic-root replacement allows broad resection of infected tissue down to healthy myocardium, excludes abscess cavities from systemic pressure, and provides redundant tissue to patch residual defects.[9] By reducing the amount of prosthetic material left in an infected bed, homografts have been associated with lower rates of reinfection in complex aortic-valve endocarditis, and the antibiotic-permeable cryopreserved homograft has been reported to resist biofilm bacterial infection.[10][9] In one large series, endocarditis was the primary indication for homograft aortic valve replacement in roughly half of cases.[2]

Congenital heart disease and the right ventricular outflow tract Pulmonary homografts are widely used to reconstruct the right ventricular outflow tract (RVOT) in congenital heart surgery, where they serve as valved conduits between the right ventricle and the pulmonary artery.[3][11]

The Ross procedure In the Ross procedure, the patient's own pulmonary valve (a pulmonary autograft) is transplanted into the aortic position, and a pulmonary homograft from a deceased donor is then used to replace the patient's pulmonary valve and reconstruct the right ventricular outflow tract.[3][11] The Ross procedure is particularly favored for children and young adults and for patients who wish to avoid anticoagulation, because the living autograft in the aortic position can grow and maintains native valve physiology.[4][11] (See also Heart transplantation for whole-organ transplantation, which is a distinct procedure.)

Advantages

• No lifelong anticoagulation. Unlike mechanical valves, homografts do not require lifelong vitamin K antagonist (warfarin) anticoagulation, avoiding the associated bleeding risk, monitoring burden, and drug and food interactions.[4][12]
• Resistance to infection. Homografts have a high resistance to endocarditis and reinfection, which underlies their preferred use in infected surgical fields.[2][10]
• Favorable hemodynamics. The stentless allograft provides low transvalvular gradients and good effective orifice area, useful in small annuli.[2][4]
• Suited to younger patients and small annuli. Homografts and the Ross procedure are commonly chosen for children, young adults, women of childbearing potential, and patients with small aortic roots.[4][1]
• Thromboembolic profile. Homografts carry a low risk of thromboembolic events relative to mechanical valves.[2]

Limitations

• Limited durability and structural valve degeneration (SVD). Like other biological valves, homografts lack living resident cells able to maintain and repair the valve matrix, so they undergo progressive structural valve degeneration; when aortic homografts degenerate, they predominantly calcify, which can produce stenosis or leaflet tearing.[13][14]
• Eventual reoperation. Durability is strongly age dependent. Reported median time to reoperation for SVD ranges from roughly 11 years in patients aged 0 to 25 years to about 25 years in patients older than 50; long-term series report on the order of 70 to 83 percent freedom from reintervention at 10 years, with lower figures in complex endocarditis cases. (Figures as of June 2026.)[13]
• Calcification accelerated in the young. Structural deterioration is more pronounced in younger patients, in part because of immunologic mechanisms that promote tissue mineralization.[12][13]
• Supply constraints. Homografts depend on the availability of suitable deceased human donors and on tissue-bank processing capacity, so supply is more limited than for manufactured prosthetic valves.[4][1]

Recovery and processing

Heart-valve homografts are recovered from deceased human donors, who may be heart-beating (brain-dead) donors or, in some programs, non-heart-beating donors; valve donors are not necessarily solid-organ donors, since a heart unsuitable for transplantation may still yield usable valves.[6][2] After aseptic retrieval, most heart-valve banks worldwide treat the tissue with low-dose antibiotic decontamination, then cryopreserve it and store it at ultralow temperature until implantation.[6] Reported processing conditions include storage of fresh allograft tissue in cold saline, antibiotic incubation, controlled-rate freezing, and storage of cryopreserved valves at roughly −135 °C to −196 °C (for example in the vapor phase or liquid phase of liquid nitrogen).[6][15] Processing and cryopreservation methods are regarded as among the most important determinants of the long-term clinical performance of biological heart valves.[15]

Tissue banks operate quarantine protocols that isolate unverified allografts until donor screening and testing confirm eligibility.[15] In North America most heart-valve banks follow the standards of the American Association of Tissue Banks (AATB), which was founded in 1976 and published its first comprehensive standards in 1984.[15] (See also Tissue bank.)

Donor screening and FDA regulation

In the United States, allograft heart valves that meet the criteria in FDA's tissue regulations are regulated as human cells, tissues, and cellular and tissue-based products (HCT/Ps) under section 361 of the Public Health Service Act and 21 CFR Part 1271, and are overseen by FDA's Center for Biologics Evaluation and Research (CBER).[7][8] This is a distinct regulatory pathway from whole-organ transplantation, and FDA has noted that procedures such as "partial heart transplantation" raise separate considerations from the use of conventional heart-valve allografts.[7]

Any establishment engaged in the manufacture of HCT/Ps, including steps in recovery, processing, storage, packaging, and distribution, as well as screening and testing of the tissue donor, is subject to the applicable requirements of 21 CFR Part 1271.[8] Subpart C of Part 1271 sets out donor-eligibility requirements: the establishment responsible for the determination must find a donor eligible based on donor screening (for risk factors for, and clinical evidence of, relevant communicable disease) under § 1271.75 and on donor testing for relevant communicable disease agents under §§ 1271.80 and 1271.85.[8] (See also Organ donation and FDA regulation of human tissue (HCT/Ps).)

Comparison with other valve substitutes

The table below summarizes general characteristics of the principal valve-substitute classes. Individual choice depends on patient age, anatomy, comorbidities, infection status, and preferences, and should be made by the treating cardiac surgical team.

| Feature | Homograft / allograft (human) | Bioprosthetic xenograft (bovine / porcine) | Mechanical valve | |---|---|---|---| | Source | Deceased human donor[2] | Animal tissue (cow pericardium or pig valve)[12] | Manufactured (carbon / metal)[12] | | Lifelong anticoagulation | Not required[4] | Not routinely required[12] | Required (warfarin)[12] | | Durability | Limited; degenerates by calcification, age-dependent[13] | Limited; structural degeneration, age-dependent[12] | Very long / durable[12] | | Infection resistance | High; preferred in infected fields[2][10] | Lower than homograft in infected fields[9] | Lower; prosthetic material at risk[9] | | Typical use considerations | Endocarditis, congenital disease, Ross procedure, young patients, small annuli[2][4] | Older patients who wish to avoid anticoagulation[12] | Younger patients accepting anticoagulation for durability[12] | | Supply | Donor-dependent, limited[4] | Manufactured, broadly available[12] | Manufactured, broadly available[12] |

Current guidance generally favors mechanical valves in younger patients (often cited as under about 50 years) where durability is prioritized and anticoagulation is acceptable, and bioprosthetic valves in older patients (often cited as over about 70 years) to avoid anticoagulation, with homografts and the Ross procedure occupying specific niches such as endocarditis, congenital disease, and selected young patients. (Thresholds as of June 2026.)[12][4]

History

The first orthotopic human implantation of an aortic-valve homograft was performed by Donald Ross in London in 1962, with Sir Brian Barratt-Boyes performing the procedure in Auckland, New Zealand, the same year.[5][16] Antibiotic sterilization of homografts was introduced at Green Lane Hospital in New Zealand by Barratt-Boyes in 1968, and cryopreservation was introduced by O'Brien in 1975, establishing the cryopreserved allograft used today.[5][6] Donald Ross subsequently applied the pulmonary autograft technique that bears his name, reporting clinical experience in 1967.[5] More recent work has explored decellularized homografts, which remove donor cellular components to reduce immune response and calcification.[1][13]

See also

• Tissue bank
• FDA regulation of human tissue (HCT/Ps)
• Heart transplantation
• Organ donation

References

• Helder MRK et al. "The Use of the Cryopreserved Aortic Homograft for Aortic Valve Replacement: Is It Still an Option?" PMC. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10299650/
• (Same review as above; aortic homograft indications, endocarditis as primary indication, hemodynamics and outcomes.) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10299650/
• "Ross procedure." Wikipedia (summary of pulmonary autograft to aortic position and pulmonary homograft for RVOT reconstruction). https://en.wikipedia.org/wiki/Ross_procedure
• "Stentless Autograft/Homograft Aortic Valve Replacement." StatPearls, NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK559299/
• "Ross' first homograft replacement of the aortic valve." The Annals of Thoracic Surgery. https://www.annalsthoracicsurgery.org/article/0003-4975(91)91315-M/fulltext
• "Transplantation of cryopreserved human heart valves in Europe: 30 years of banking in Brussels and future perspectives." PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC7853167/
• "Information for Health Professionals on 'Partial Heart Transplantation.'" U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/tissue-tissue-products/information-health-professionals-partial-heart-transplantation
• "21 CFR Part 1271: Human Cells, Tissues, and Cellular and Tissue-Based Products." Electronic Code of Federal Regulations (eCFR). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-L/part-1271
• "Homograft reconstruction of the aortic root for endocarditis with periannular abscess: a 17-year study." PubMed. https://pubmed.ncbi.nlm.nih.gov/15982588/
• "Over 20 years experience with aortic homograft in aortic valve replacement during acute infective endocarditis." European Journal of Cardio-Thoracic Surgery, Oxford Academic. https://academic.oup.com/ejcts/article/50/6/1158/2726554
• "Modified Ross procedure with four different strategies for right ventricular outflow tract reconstruction." Multimedia Manual of Cardio-Thoracic Surgery. https://mmcts.org/tutorial/2005
• "Age-Specific Outcomes of Bioprosthetic vs. Mechanical Aortic Valve Replacement: Balancing Reoperation Risk with Anticoagulation Burden." PMC. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11277715/
• "Durability of Homografts Used to Treat Complex Aortic Valve Endocarditis." The Annals of Thoracic Surgery. https://www.annalsthoracicsurgery.org/article/S0003-4975(14)02090-6/pdf
• "Degeneration of Bioprosthetic Heart Valves: Update 2020." Journal of the American Heart Association (AHA). https://www.ahajournals.org/doi/10.1161/JAHA.120.018506
• "Tissue Bank (Medical Storage): Overview"; and AATB "Standards for Tissue Banking" (cryopreservation, quarantine, AATB founding 1976 / first standards 1984). https://a498c38321542e3afc7a-6340203f328f3cd60aa87439c450317d.ssl.cf2.rackcdn.com/aatb_22c51a909c525ed6c3d26b2b9ccbff84.pdf
• "Milestone Operations in Heart Valve and Aortic Replacement: Anniversaries Worth Remembering." PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC11219127/