The work is devoted to the study of the effectiveness of modern methods of
myocardial protection in the conditions of artificial circulation (AC) when performing
mitral valve replacement (MVR) in patients with mitral valve insufficiency (MVI). The
aim of this study was to reduce myocardial damage during surgical treatment of mitral
insufficiency during mitral valve replacement in conditions of artificial circulation by
using the optimal cardioprotection method.
The study analyzed the results of surgical intervention of MVR, which was
performed in 85 patients with MVI. All patients were divided into 2 groups according to
the cardioprotection method. Patients of the Group 1 with MVR were treated with
crystalloid cardioplegia (CC) (Bernstein solution) as a method of cardioprotection for
myocardium protection, patients of the Group 2 were treated with artificial electric
ventricular fibrillation (AEF) with intermittent aortic compression (IAC) in conditions of
moderate hypothermia.
The study was conducted in the following stages: 1) before surgical
intervention, 2) at the end of the artificial circulation (AC, perfusion), 3) before
transfer to the intensive care unit (ICU), 4) before transfer from ICU. The following
indicators were recorded at these stages: End-Diastolic Volume (EDV), End-Systolic
Volume (ESV), Heart Rate (HR), pulmonary artery systolic pressure (PAPs) and
Global Longitudinal Myocardial Deformation (GLD); troponin I, natriuretic peptide
NT-proBNP, alanine aminotransferase (ALAT), aspartate amino transferase (ASAT),
creatine phosphokinase (CFK), creatine phosphokinase – MB (CFK-MB),
hemoglobin (Hb), lactate concentration in blood; hematocrit (Ht), arterial blood
oxygen saturation and mixed venous saturation (SaО2 і Sv О2), partial pressure of
arterial oxygen and partial oxygen pressure in mixed venous blood (paО2 і pvО2).
The obtained parameters were used to calculate the left ventricular ejection
fraction (LVEF), the shock volume (UO), stroke volume (SV), end-diastolic index (EDI)
of the left ventricle (LV), end-systolic index (ESI) of the LV, cardiac output (CO),
cardiac index (CI), the ratio of CFK-MB and CFK, arteriovenous oxygen difference
(Sa-vO2), arterial and venous oxygen content (CaО2 і Cv О2), transport, consumption, and
oxygen extraction coefficient (TО2, VО2 і EО2 , respectively).
The study of the initial state of the circulatory system of the examined patients
showed that the state of the intra-cardiac and central hemodynamics of the examined
patients was caused by the main pathology – MVI. EDI in patients of Group 1 was 77.7
± 1.2 ml/m2
, in patients of Group 2 – 79.3 ± 1.4 ml/m2
(p> 0.5), ESI was 36.6 ± 0.6
ml/m2
and 37.6 ± 0.9 ml/m2
(p> 0.2) respectively, while the ejection fraction (EF) was
52.7 ± 0.8% in Group 1 patients and 52.6 ± 0.7% in Group 2 patients (p> 0.1). SV in
patients of Group 1 was 41.1 ± 1.1 ml/m2
and SV in patients of Group was 41.8 ± 0.92
ml/m2
(p> 0.5). CI was 3.20 ± 0.08 l/min∙m2
, and 3.16 ± 0.06 l/min∙m2, respectively (p >
0.5).
GLD was reduced in absolute value equally in patients of the examined groups.
In patients of Group 1, GLD was 12.4 ± 0.8%, in patients of Group 2 – 12.5 ± 0.9%
(p> 0.5). PAPs in patients of Group 1 was 47.0 ± 0.9 mm Hg, and in patients of
Group 2 – 47.6 ± 0.8 mm Hg.
Before the surgery, minor myocardial damage levels in patients did not exceed
normal values, which indicates the absence of any myocardial damage. A strong
correlation was found between NT proBNP and GLD in both groups of patients
examined; the correlation coefficient was the same in both groups and was 0.81±0.05.
A significant correlation between NT proBNP and EF levels was also recorded. In
Group 1, the correlation coefficient was 0.65 ± 0.09, in Group 2 – 0.56 ± 0.10. ALAT
and ASAT levels were closely correlated with the value of GLD, although the
activity of these enzymes did not exceed the norm. This probably suggests a greater
propensity of the myocardium to hypoxic damage due to volume overload and
excessive dilation.
Indicators of transport and oxygen consumption in both groups were the same
and were within the normal range. Arteriovenous difference in oxygen saturation of
hemoglobin (ΔSO2) in Group 1 was at the level of 23.1 ± 0.9%, in Group 2 – 23.2 ±
0.6%, in oxygen voltage (ΔpO2) - 46.9 ± 1, 1 and 47.9 ± 1.0 mm Hg, in oxygen
content - 0.052 ± 0.002 and 0.053 ± 0.001 l/l. The transport of oxygen (Tо2) in
patients of Group 1 was 0.619 ± 0.015 l/min∙m2
, in patients of Group 2 –
0.611±0.014 l/min∙m2
, the oxygen consumption (VO2) – 0.163 ± 0.004 and 0.164 ±
0.003 l/min∙m2
respectively, the tissue oxygen extraction coefficient (EO2) – 26.8 ±
0.8 and 27.3 ± 0.6% (in all cases p> 0.5).
