Abstract
The field of cardiac surgery has evolved significantly over the past few years. New surgicaltechniques and developments have change patient survival and outcome in congenital,
valvular, and coronary pathology. Cardiac magnetic resonance (CMR) is a valuable imaging
tool, which has gained recognition in the guidelines due it’s accurate assessment of
biventricular function, tissue characterization and flow analysis, and is increasingly being
considered as a valuable alternative in the decision-making process of cardiac surgery
patients, due to better spatial resolution than echocardiography, and the advantage of
using non-ionizing radiation in contrast to computed tomography (CT). This thesis
encompasses a series of investigations which aim to determine the current role and use
of CMR in cardiac surgery, accuracy and additional value of new emerging sequences and
its value on growing new patient populations which require regular follow up.
In Chapter 2, the current use of CMR in the decision-making process in patients
undergoing coronary artery bypass surgery was analysed. Patients accepted for isolated
CABG were recruited and clinical data was acquired for those who underwent CMR preoperatively for assessment of ischaemic heart disease, and for those who did not. Both
groups (with CMR prior to CABG and those with no CMR performed) were compared, and
they differed significantly in severity of left ventricular function, severity of angina and
presence of coronary occlusion; with moderate-severe left ventricular dysfunction, and
presence of coronary occlusion being independent predictors of a patient having a clinical
request for CMR.
In Chapter 3, a comparison of markers of severity of regurgitation was caried out in
patients with severe primary mitral regurgitation (MR) undergoing 2D and 3D
echocardiography, standard phase contrast CMR and novel 4D flow sequence. There was
mild linear correlation between mitral regurgitant volume calculated by conventional
CMR phase contrast and regurgitant volume calculated by PISA and EROA (2D
echocardiography parameters). Furthermore, there was mild linear correlation between
mitral regurgitant volume calculated by standard phase-contrast CMR with regurgitant
volume calculated by the 3D echocardiography volumetric method. Regurgitant volume
assessed by CMR 4D flow showed moderate correlation with 2D echocardiography (PISA
and EROA), and agreement with regurgitant volume calculated with 3D echocardiography.
In a separate sub-study, a multiparametric comparison of data from CMR scans was
performed in patients with severe MR before and after surgery, and compared with
3
healthy volunteers. This showed significantly higher values of native T1 mapping and LV
end-diastolic volumes in severe MR patients when compared to healthy volunteers with
a return to normalization after mitral valve surgery.
Finally, Chapter 4 aimed to determine adaptive changes and imaging characteristics of
young adults who underwent the arterial switch operation (ASO) for correction of
transposition of the great arteries (TGA). A comprehensive CMR protocol included
adenosine stress first pass perfusion imaging. Results showed biventricular volumes,
ejection fraction and left ventricular longitudinal strain values within normal ranges for
age and gender, and normal aortic and main pulmonary artery (MPA) dimensions. Native
T1 mapping values were also within normal range, and there was no evidence of inducible
myocardial ischaemia on any of the subjects included in the study, similarly to what
previously reported for this cohort in the literature.
In conclusion, CMR has an important complementary role to other imaging techniques in
all the stages of the surgical process: from patient selection, to determining severity of
disease and for short and long term follow up. With the advent of new sequences and
techniques, large cohort multicentre trials are needed to truly understand the full
potential and accuracy of these new CMR developments
| Date of Award | 1 Oct 2024 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Gianni D Angelini (Supervisor) & Chiara Bucciarelli-Ducci (Supervisor) |