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Cardiac CT in heart transplant patients

Abstract
Philips CT Clinical Science Philips Healthcare • USA

Andrea Bartykowszki, MD

MTA-SE Cardiovascular Imaging Research Group

Heart and Vascular Center

Semmelweis University

Budapest

Hungary

andrea.bartykowszki@cirg.hu

 

Cardiac allograft vasculopathy (CAV) is the leading cause of death after the first year of heart transplantation (HTX). The overall prevalence of the disease at 1, 5, and 10 years after transplantation is 8%, 30%, and 50% respectively.

 

Both immunologic and non-immunologic factors contribute the development of diffuse concentric intimal hyperplasia, which leads to ischemic consequences, including graft failure, arrhythmias, myocardial infarction, but because the denervated nature of transplanted heart it rarely causes angina. Therefore the international guidelines recommend annual or biannual assessment of coronary status. The gold standard method for the evaluation of CAV is invasive coronary angiography (ICA).

 

The angiographic diagnosis of CAV is often more difficult than the non-transplant coronary atherosclerotic lesions, and the interobserver variation is high, since vasculopathy is a diffuse process. The sensitivity of ICA can be increased with intravascular ultrasound (IVUS) and optical coherence tomography (OCT). Coronary CT angiography (CTA) could be an alternative method in the diagnosis of CAV. The non-invasive coronary CTA has high diagnostic accuracy. It can detect 1.5-2 times more coronary segments than ICA with increased wall thickness in HTX and non-HTX patients. However, the absence of afferent and efferent innervation of the transplanted hearts results in higher resting heart rates (HR), which may compromise the diagnostic performance of coronary CTA. In addition, due to the higher HR retrospective ECG gating has been used in HTX patients, which resulted in higher radiation dose. These concerns precluded the widespread use of coronary CTA in HTX patients. However, the lack of autonomic innervation also results a steady HR with minimal HR variability. The steady HR of HTX patients might provide a unique opportunity to scan these patients with low radiation dose while achieving good image quality.

 

In a retrospective, matched case-control cohort study our working group evaluated coronary CTA image quality of 50 HTX patients and 50 matched non-HTX controls. The non-HTX group was selected from our clinical database of 2500 coronary CTA exams based on matching criteria that may influence image quality. Degree of motion artefacts were evaluated per segment basis on a four-point Likert-type scale. We found that in the HTX group significantly more segments had excellent image quality than in the non-HTX group. Furthermore, in the HTX group the number of non-diagnostic segments were approximately one-third of that of the non-HTX group.

 

Based on our results ECG-triggered coronary CTA exams of HTX patients have a significantly better image quality than non-HTX patients with similar HR. Furthermore, HTX patients can be scanned with prospective ECG-triggering scan mode with low radiation dose (average effective radiation dose 3.7 mSv). Therefore, coronary CTA might be a promising non-invasive alternative to routine catheterization during follow-up of HTX patients to diagnose CAV.

 

 

References

  1. Badano LP, Miglioranza MH, Edvardsen T, et al. European Association of Cardiovascular Imaging/Cardiovascular Imaging Department of the Brazilian Society of Cardiology recommendations for the use of cardiac imaging to assess and follow patients after heart transplantation. European Heart Journal - Cardiovascular Imaging. 2015;16(9):919-48.
  2. Mehra MR, Crespo-Leiro MG, Dipchand A, et al. International Society for Heart and Lung Transplantation working formulation of a standardized nomenclature for cardiac allograft vasculopathy-2010. The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation. 2010;29(7):717-27.
  3. Costanzo MR, Dipchand A, Starling R, et al. The International Society of Heart and Lung Transplantation Guidelines for the care of heart transplant recipients. The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation. 2010;29(8):914-56.

 

Figure A: Curved multiplanar reconstruction of the RCA of a heart transplant patient with a heart rate of 75 bpm. No motion artefact is visible. Figure B: Curved multiplanar reconstruction of the RCA of a non-heart transplant patient with a heart rate of 75 bpm. Motion artefact is visible on the proximal and mid segment of the RCA. (RCA – Right coronary artery).

 

Coronary CTA of a heart transplant recipient. Curved multiplanar reconstruction of the LAD. Figure A: First year follow-up CT. Small calcified lesion causes wall irregularity on the proximal segment of the LAD. Figure B: Second year follow-up CT. Diffuse luminal narrowing is visible along the proximal and mid segment of the LAD. (LAD - Left anterior descending artery, LV – Left ventricle).


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Abstract
13th MDCT Users Meeting abstracts, artifacts, Cardiac, coronary angiography, curved MPR, ECG-gated, follow up, image quality, LAD, left ventricle, prospective, RCA, retrospective, Vascular
 

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