[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Heart](https://durgical.com/en/general-pathology/areas/heart/) › Heart transplantation and cardiac devices

# Heart transplantation and cardiac devices

- Topic

Replacing a failing heart or valve saves lives but brings its own problems: rejection, clots, infection and wear.

Updated Nov 12, 2026

## Key points

- Acute cellular rejection: lymphocytes with myocyte damage on endomyocardial biopsy; graded by severity.
- Antibody-mediated rejection: capillary injury with C4d deposition and donor-specific antibodies.
- Allograft vasculopathy: concentric intimal proliferation of the entire coronary tree; silent ischemia because the heart is denervated.
- Immunosuppression raises infections and post-transplant lymphoproliferative disorders (Epstein–Barr virus).
- Mechanical valves: thrombosis and thromboembolism, bleeding from anticoagulation; bioprosthetic valves: calcification, tears, structural degeneration.
- All prosthetic valves: endocarditis (often at the sewing ring, with ring abscess), paravalvular leak, hemolysis.

## What it is

Heart transplantation treats end-stage heart failure. The main problems are acute rejection (T-cell mediated or antibody-mediated), infections and tumours from immunosuppression, and cardiac allograft vasculopathy, a diffuse concentric intimal thickening of the coronary arteries that limits long-term survival. Prosthetic valves are mechanical (durable, but needing anticoagulation) or bioprosthetic (tissue valves that degenerate and calcify). Ventricular assist devices support a failing ventricle but risk thrombosis, bleeding, stroke and infection.

## Complications of replacing the heart or its valves

| Treatment | Main complications | Pathology | Timing |
| --- | --- | --- | --- |
| Heart transplant | Rejection, infection, lymphoma | Lymphocytic infiltrate with myocyte injury; C4d in capillaries | Weeks to years |
| Heart transplant (late) | Allograft vasculopathy | Diffuse concentric intimal thickening of coronary arteries | Years |
| Mechanical valve | Thrombosis, embolism, bleeding, endocarditis | Thrombus on the valve; ring abscess | Any time |
| Bioprosthetic valve and assist device | Calcification and tears (valve); thrombosis, driveline infection, bleeding (device) | Dystrophic calcification; thrombus; infection | Years (valve); months (device) |

## Clinical notes

- Transplant recipients undergo surveillance biopsies and coronary imaging; chest pain is often absent in vasculopathy.

## Memory aid

A new heart can be rejected fast or choked slowly by its own arteries; a new valve clots if metal, calcifies if tissue, and gets infected either way.

## Test yourself

Think of the answer, then tap the question to see it.

## What is cardiac allograft vasculopathy?

A diffuse, concentric intimal proliferation of the coronary arteries of a transplanted heart, the main limit to long-term graft survival.

## Why do mechanical valves require lifelong anticoagulation?

Their surfaces are thrombogenic, so without anticoagulation thrombi form and embolise.

## What is the main long-term failure mode of bioprosthetic valves?

Structural degeneration with calcification and leaflet tears.

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## Elsewhere in DurgiPedia

- [Transplant rejection: hyperacute, acute, chronic](https://durgical.com/en/immunology/transplant-rejection-hyperacute-acute-chronic/)

## Connections

## Related 4

- [Pathology after angioplasty, stents and grafts](https://durgical.com/en/general-pathology/pathology-after-angioplasty-stents-and-grafts/)
- [Infective endocarditis](https://durgical.com/en/general-pathology/infective-endocarditis/)
- [Arterial vs venous thrombi; mural thrombi and lines of Zahn](https://durgical.com/en/general-pathology/arterial-vs-venous-thrombi-mural-thrombi-and-lines-of-zahn/)
- [Vessel wall response to injury](https://durgical.com/en/general-pathology/vessel-wall-response-to-injury/)

## Related conditions 3

- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/)
- [Aortic Valve Stenosis](https://durgical.com/en/conditions/aortic-valve-stenosis/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Heart Transplantation | Heart Transplant | MedlinePlus](https://medlineplus.gov/hearttransplantation.html) (MedlinePlus, US National Library of Medicine, 2025); [Infective Endocarditis](https://www.ncbi.nlm.nih.gov/books/NBK557641/) (StatPearls (NCBI Bookshelf), 2025).

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Source: https://durgical.com/en/general-pathology/heart-transplantation-and-cardiac-devices/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/heart-transplantation-and-cardiac-devices/