Cardiac Transplantation Pathology

Cardiac Transplantation Pathology

Cardiac Transplantation Pathology

On this page

Indications & Biopsy - Heartfelt Handoff

  • Indications for Transplant:
    • End-stage heart failure (HF) refractory to maximal medical/device therapy.
      • NYHA Class III (ambulatory) or IV.
    • Common causes:
      • Dilated Cardiomyopathy (DCM) - leading cause.
      • Ischemic Cardiomyopathy (ICM).
      • Severe, inoperable valvular or congenital heart disease.
    • Refractory life-threatening arrhythmias.
    • Predicted < 1-year survival without transplant.
  • Endomyocardial Biopsy (EMB):
    • Primary tool for monitoring allograft rejection.
      • Acute Cellular Rejection (ACR).
      • Antibody-Mediated Rejection (AMR).
    • Procedure: Right ventricular samples via jugular/femoral vein.
    • Grading: ISHLT classification for ACR severity.
    • Protocol: Routine surveillance, frequency ↓ over time.
> ⭐ Endomyocardial biopsy (EMB) is the gold standard for monitoring cardiac allograft rejection.

Rejection Types - Immune System Scuffles

  • Immune responses against donor heart. Classified by timing & mechanism.
![Cardiac Allograft Biopsy Evaluation Methods](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Pathology_Cardiac_Pathology_Cardiac_Transplantation_Pathology/43f2c66f-ced8-4acc-8c5b-a4100263ed24.jpg)
  • Hyperacute Rejection:

    • Immediate (minutes-hours).
    • Mediator: Pre-formed Donor-Specific Antibodies (DSAs) vs ABO/HLA.
    • Patho: Thrombosis, necrosis.

    ⭐ Hyperacute rejection, occurring minutes to hours post-transplant, is mediated by pre-formed donor-specific antibodies (DSAs) against ABO or HLA antigens.

  • Acute Cellular Rejection (ACR):

    • Weeks-months (common).
    • Mediator: T-lymphocytes.
    • EMB: Lymphocytic infiltrate, myocyte damage (ISHLT Grade 0R-3R).
  • Acute Antibody-Mediated Rejection (AMR):

    • Days-months.
    • Mediator: DSAs (often anti-HLA), complement.
    • EMB: Microvascular inflammation, C4d deposition (ISHLT pAMR Grade 0-3).
  • Chronic Rejection (Cardiac Allograft Vasculopathy - CAV):

    • Months-years (leading late cause).
    • Patho: Diffuse concentric intimal thickening of coronaries ("onion skinning").
    • Result: Ischemia, MI, graft failure.

Grading Rejection - Scorecard Showdown

  • Standardized assessment of rejection severity.
  • Acute Cellular Rejection (ACR) - ISHLT 2004 Grades:
    • Grade 0R: No rejection.
    • Grade 1R (Mild): Interstitial/perivascular infiltrate; ≤1 focus myocyte injury.
    • Grade 2R (Moderate):2 foci infiltrate, myocyte injury.
    • Grade 3R (Severe): Diffuse infiltrate, multifocal injury ± edema, hemorrhage, vasculitis.
  • Antibody-Mediated Rejection (AMR) - ISHLT Pathologic (pAMR) Grades:
    • pAMR 0: Negative.
    • pAMR 1(H+): Histology + Immunopathology (C4d/C3d/CD68).
    • pAMR 1(I+): Immunopathology only.
    • pAMR 2: Severe/diffuse Histology + Immunopathology.
    • pAMR 3: Severe changes (capillary injury, hemorrhage, necrosis) + Immunopathology.
    • Correlate with DSA & clinical status.

⭐ The International Society for Heart and Lung Transplantation (ISHLT) provides standardized grading criteria for acute cellular rejection (ACR) and antibody-mediated rejection (AMR).

Chronic Rejection & Complications - Long-Haul Headaches

  • Cardiac Allograft Vasculopathy (CAV): Primary chronic rejection form; major cause of late graft loss.
    • Patho: Diffuse, concentric intimal thickening of coronary arteries (epicardial & intramyocardial), leading to luminal stenosis.
    • Mechanism: Endothelial injury, smooth muscle cell proliferation, inflammation, ECM deposition. Immune (alloantibodies, T-cells) & non-immune factors (e.g., CMV, dyslipidemia).
    • Clinical: Often silent ischemia/MI (denervated graft), arrhythmias, progressive heart failure.
    • Dx: Intravascular ultrasound (IVUS) is gold standard; angiography less sensitive for early disease.

⭐ Cardiac Allograft Vasculopathy (CAV) is a form of chronic rejection characterized by diffuse, concentric intimal thickening of coronary arteries, leading to late graft failure.

  • Other Major Long-Term Complications:
    • Malignancy: Increased risk. Post-Transplant Lymphoproliferative Disorder (PTLD) - often EBV-driven; skin cancers (SCC > BCC).
    • Infections: Opportunistic due to chronic immunosuppression (e.g., CMV, Aspergillus, Pneumocystis jirovecii).
    • Drug Toxicity: Calcineurin inhibitor (CNI) nephrotoxicity; steroid-induced diabetes, hypertension, dyslipidemia. Allograft Vasculopathy vs Atherosclerosis

High‑Yield Points - ⚡ Biggest Takeaways

  • Hyperacute rejection: Minutes to hours, pre-formed anti-donor Abs (ABO/HLA); widespread thrombosis, ischemic necrosis.
  • Acute Cellular Rejection (ACR): T-cell mediated, peaks 1-3 months; Endomyocardial Biopsy (EMB) shows lymphocytic infiltrate, myocyte damage.
  • Antibody-Mediated Rejection (AMR): Donor-specific Abs (DSA), C4d deposition in capillaries, microvascular inflammation, poor prognosis.
  • Chronic Rejection (Cardiac Allograft Vasculopathy - CAV): Major long-term limit; diffuse concentric intimal thickening of coronaries, leading to ischemia, graft failure.
  • Infections: Major mortality risk with immunosuppression; CMV, fungal, bacterial pathogens common.
  • Post-Transplant Lymphoproliferative Disorder (PTLD): EBV-driven B-cell proliferation; risk ↑ with intensity of immunosuppression.

Practice Questions: Cardiac Transplantation Pathology

Test your understanding with these related questions

After 4 months of renal transplantation, a patient is likely to develop which infection?

1 of 5

Flashcards: Cardiac Transplantation Pathology

1/10

Reperfusion of irreversibly-damaged cells post-MI may result in _____ influx, leading to hypercontraction of myofibrils (contraction band necrosis)

TAP TO REVEAL ANSWER

Reperfusion of irreversibly-damaged cells post-MI may result in _____ influx, leading to hypercontraction of myofibrils (contraction band necrosis)

Ca2+

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial