Hemodynamic characterization of cardiac disease and aortopathy after valve sparing aortic root replacement, mechanical aortic valve implantation or septal myectomy: a 4D-flow MRI study

Valve sparing aortic root replacement is a cardiac surgery procedure used to
treat aneurysms of the aortic root without replacing the aortic valve. Two
valve-sparing procedures are currently being performed in modern surgical
practice: the David *reimplantation* technique and the Yacoub *remodeling*
procedure. Many studies have been conducted comparing these treatment
modalities and have found that early and late mortality, cardiopulmonary bypass
time and aortic cross clamp times were comparable. Several studies have
reported that postoperative freedom from aortic insufficiency was more frequent
after the David procedure than the Yacoub procedure, raising the question as to
whether technique-specific differences in blood flow are associated with
postoperative aortic valve function.

Aortic valve stenosis is the most common form of valvular heart disease and is
often a progressive disease. Surgical aortic valve replacement (AVR) is the
only definitive treatment for severe stenosis and can be performed by replacing
the calcified aortic valve with either a mechanical valve or a bioprosthetic
tissue valve. Mechanical valves are made of pyrolytic carbon and are designed
to last a lifetime. However, it is possible that their bicuspid design induces
changes in wall stress and blood flow patterns in the aortic root. It is
believed that turbulent flow across aortic valve prostheses could lead to
increased wall shear stress, influencing aortic wall degradation and resulting
in aortic root dilatation.

Hypertrophic cardiomyopathy (HCM) is a heterogeneous disease of the myocardium
and is characterized by increased left ventricular wall thickness. Left
ventricular outflow tract (LVOT) obstruction occurs in up to 70% of patients
and can be life-threatening. The most commonly performed surgical procedure in
patients with HCM is septal myectomy, a procedure in which a part of the
myocardial septum is excised, resulting in relieve of the LVOT obstruction and
restoration of blood flow through the aorta. However, very little is known
about the effect of this intervention on the blood flow patterns through the
aortic valve and into the aortic root and ascending aorta.

Recently, 4D flow magnetic resonance imaging (MRI) has become available to
assess flow patterns and hemodynamic parameters across heart valves in multiple
dimensions over time. This allows for an objective analysis of blood flow and
other hemodynamic parameters in these patients.

- investigate blood flow patterns and energy loss due to viscous dissipation or
turbulent kinetic flow in the aorta in patients with aortic root grafts.
- determine whether turbulent flow or increased wall shear stress is present in
patients with mechanical aortic valve prostheses
- investigate blood flow patterns and energy loss due to viscous dissipation or
turbulent kinetic flow in the aorta in patients after septum myectomy.

Cross-sectional retrospective pilot study

No risks
Total scantime is approximately 40 minutes, if possible planned during regular
visit in outpatient clinic