The assessment of right ventricular function during and following routine cardiac surgery and the evaluation of preserving pericardial integrity
Author(s)
Unsworth, Bethan
Type
Thesis
Abstract
The assessment of right ventricular tricuspid annular velocities and excursion is a robust and
common technique of evaluating right ventricular function. The measurement of peak systolic
myocardial velocities using pulsed wave tissue Doppler imaging correlates well with
estimates of systolic function. It is well known that right ventricular velocities are
significantly reduced in patients following cardiac surgery; however the precise cause of this
post-operative phenomenon remains unknown despite a number of proposed mechanisms. In
this thesis I have carried out observational studies before, during and after surgery in number
of patients undergoing different cardiac and thoracic operations.
I found using intra-operative transoesophageal and pre and post-operative transthoracic
echocardiography that the onset of right ventricular myocardial velocity reduction is
immediately marked by the full opening of the pericardium following traditional-midline
thoracotomy. I also identified that this reduction is present in all operations where the
pericardium is opened fully regardless of the underlying pathology i.e. cardiac or noncardiac.
By measuring simultaneous pericardial support pressures and intra-operative
transoesophageal velocities during a staged pericardiotomy I also showed, in patient where
there pericardium was to be opened fully, that this loss occurs consistently and specifically
during the second-stage of a three-staged pericardiotomy which demonstrated in a novel way
the substantial and localised mechanical support provided by the intact pericardium.
Furthermore, I found that right ventricular longitudinal velocities do not reduce in those
patients undergoing minimally invasive cardiac surgery where pericardial integrity is
preserved.
I believe this thesis has helped to prune the range of possible mechanism for this post
operative phenomenon which is frequently seen and commented upon.
common technique of evaluating right ventricular function. The measurement of peak systolic
myocardial velocities using pulsed wave tissue Doppler imaging correlates well with
estimates of systolic function. It is well known that right ventricular velocities are
significantly reduced in patients following cardiac surgery; however the precise cause of this
post-operative phenomenon remains unknown despite a number of proposed mechanisms. In
this thesis I have carried out observational studies before, during and after surgery in number
of patients undergoing different cardiac and thoracic operations.
I found using intra-operative transoesophageal and pre and post-operative transthoracic
echocardiography that the onset of right ventricular myocardial velocity reduction is
immediately marked by the full opening of the pericardium following traditional-midline
thoracotomy. I also identified that this reduction is present in all operations where the
pericardium is opened fully regardless of the underlying pathology i.e. cardiac or noncardiac.
By measuring simultaneous pericardial support pressures and intra-operative
transoesophageal velocities during a staged pericardiotomy I also showed, in patient where
there pericardium was to be opened fully, that this loss occurs consistently and specifically
during the second-stage of a three-staged pericardiotomy which demonstrated in a novel way
the substantial and localised mechanical support provided by the intact pericardium.
Furthermore, I found that right ventricular longitudinal velocities do not reduce in those
patients undergoing minimally invasive cardiac surgery where pericardial integrity is
preserved.
I believe this thesis has helped to prune the range of possible mechanism for this post
operative phenomenon which is frequently seen and commented upon.
Date Issued
2010-10
Date Awarded
2011-11
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Francis, Darrel
Mayet, Jamil
Sponsor
British Heart Foundation and the Coronary Flow Trust at St Mary‘s Hospital
Creator
Unsworth, Bethan
Publisher Department
Medicine: National Heart and Lung Institute
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)