1. INTRODUCTION
Mitral regurgitation (MR) is the second most common disease in heart
valve surgery and affects approximately 2% of the
population.1,2 Ischemic mitral regurgitation (IMR)
ranks third among the causes of mitral valve surgery and constitutes
approximately 10% of mitral valve operation
indications.3 When we look at the causes of MR, it is
important to distinguish between primary and secondary disease groups,
especially according to the development of the disease. In primary MR,
one or more components of the valve apparatus may be affected as a
result of mitral valve degeneration, including rheumatic heart disease,
fibroelastic insufficiency, or Barlow’s disease. Endocarditis is one of
the main causes of primary MR, which is especially discussed in the
guidelines of the European Society of Cardiology and the European
Society of Cardiac and Thoracic Surgery. In secondary MR, the valve
apparatus is anatomically intact, and MR disease may develop due to
insufficiency, particularly valve closure and valve attachment points.
Secondary to MR, ischemic cardiomyopathy due to left ventricular
dilatation and dysfunction is observed.1,4
IMR develops as a complication of coronary artery
disease.5 IMD is a ventricular disease, not a valvular
disease, and it begins to be seen with regional and all-encompassing
left ventricular remodeling after AMI.6,7 Today,
morbidity and mortality due to ischemic heart disease (IHD) and its
complications are quite high. A significant number of these patients
(40%) die due to AMI and its complications.8
Ischemic mitral regurgitation is one of the most controversial problems
in cardiac surgery practice. In recent years, surgical revascularization
and mitral repair attempts have been performed in moderate and severe
ischemic mitral regurgitation. Mitral valve repairs in the heart working
with retrograde normothermic perfusion can be counted among these
interventions. These approaches not only reduce operative mortality, but
also affect long-term survival.9,10
Papillary muscle dysfunction is prominent in the acutely developing
group of these cases, which can also be classified as acute and chronic
ischemic mitral regurgitation. Papillary muscle rupture is rarely
encountered and its incidence in total acute myocardial infarctions is
less than 1%. Rupture can involve the entire muscle, or it can be seen
only in one head of the muscle. Rupture of the entire muscle is
extremely dangerous and causes severe mitral regurgitation as the
movement of half of both leaflets will be impaired. The ruptured
papillary muscle should be sutured to the adjacent ventricular free
wall. If there is damage only to the tip of the papillary muscle, not
the whole, the insufficiency will be less. The ruptured papillary muscle
head is repaired by suturing it to the papillary muscle right next to
it.
Chronic ischemic mitral regurgitation, on the other hand, develops as a
result of papillary muscle elongation secondary to infarction or due to
excessive changes in ventricular anatomy that move the papillary muscles
away from the mitral annulus. Clinically, leaflet prolapse due to
chordae rupture or papillary muscle elongation is seen in some patients.
More commonly, restricted mitral leaflet movement caused by left
ventricular anatomical changes is observed. Valve repair in ischemic
mitral regurgitation depends on the presence of restricted leaflet
movement or excessive leaflet movement. In ventricular dilatations that
develop as a result of ischemic heart disease, cases of mitral
insufficiency are frequently encountered even without papillary muscle
damage. In such cases, the papillary muscles displace laterally, causing
restricted movement of the leaflets. Pathological examinations show that
there is no annular dilatation in these patients and there is no
correlation between annulus diameter and
regurgitation.11
On the other hand, even annuloplasty alone reduces the diameter of the
annulus and eliminates the failure by providing leaflet closure. Cases
with restricted leaflet movement are only repaired by annuloplasty. In
cases where prolapse develops, other surgical repair interventions such
as papillary shortening, chordae shortening, leaflet resection are
needed in addition to annuloplasty. Cases with restricted leaflet
movement seem to have a shorter life expectancy than those with
prolapse. In ischemic mitral regurgitation, papillary muscle dysfunction
and ventricular deformation cause some problems in mitral valve repairs.
As is known, ischemic mitral insufficiency occurs as a result of changes
in ventricular anatomy. Since this condition develops after acute
myocardial infarction, there is a decrease in left ventricular function.
Patients with this condition adversely affect the outcome of cardiac
surgery procedures.12 Therefore, since the results of
long-term medical treatment in patients with mitral regurgitation are
not at the desired level, some surgeons suggest that valve replacement
surgery should be performed to prevent reoperation, assuming that mitral
regurgitation may progress.13,14
Prolidase is a cytosolic exopeptidase that cleaves proline or
hydroxyproline at the carboxyl terminal position of dipeptides. It is
found in various organs such as the brain, heart, uterus and thymus, and
in plasma.15 They have important roles in
physiological and pathological processes such as embryonic development,
wound healing, inflammation, carcinogenesis, angiogenesis, cell
migration and cell differentiation.16,17 Proline is
commonly found in the central nervous system.18 It has
been reported that proline plays a role as a neuromodulator in synaptic
transmission.19 Serum prolidase (U / L) levels have
been evaluated in many diseases and have been found to be high in
fibrotic liver disease, metabolic syndrome, hypertension, coronary
artery disease (CAD) and valve disease.20,21
In this study, we evaluated the prolidase level in patients with and
without ischemic mitral insufficiency. In conclusion, wide tissue
distribution suggests that changes in prolidase enzyme activity may gain
importance in the development and outcome of many diseases.