Background and objective: The evaluation of hemodynamics in patients with acute myocardial infarction is crucial. Intra-aortic balloon pumping or counterpulsation in patients with cardiogenic shock is supposed to be monitored exceptionally by invasive methods for assessment of hemodynamics. However, noninvasive methods might have place in monitoring these patients. The objective of the study was to evaluate the possibility of applying noninvasive methods for evaluation of hemodynamics during acute myocardial infarction complicated by cardiogenic shock and managed by intra-aortic balloon pumping.
Patients and methods: A total of 16 patients were investigated according to the study protocol. Anterior acute myocardial infarction was diagnosed in 11 (68.75%) patients, inferior--in 4 (25%), circular--in 1 (6.25%). Primary percutaneous transluminal coronary angioplasty was successfully performed in 7 (43.75%) patients, unsuccessfully--in 1 (6.25%) patient, who died within the first 18 hours. Half of patients (50%) underwent cardiac surgery within the first two weeks. Mortality rate was 68.75% (11 patients). A prospective controlled study was carried out to compare two different methods--intermittent thermodilution (ITD) and impedance cardiography (ICG)--for simultaneous cardiac output measurements in patients with acute myocardial infarction complicated by cardiogenic shock and managed by intraaortic balloon counterpulsation. Statistical analysis was performed with Bland-Altman and linear regression.
Results: Correlation coefficient was calculated comparing cardiac output values derived from ICG and ITD; it ranged from 0.24 to 0.98 in separate patients. It was observed a weak correlation of ICG and ITD measurements before initiation of intra-aortic balloon pumping--0.24-0.27 in separate cases. The correlation improved during intra-aortic balloon pumping--0.58-0.98 and at the termination of intra-aortic balloon pumping--0.67-0.97. The observed correlation was more pronounced in patients not receiving high doses of inotropes and ranged 0.58-0.98 while for patients receiving high doses of inotropes correlation was less pronounced 0.29-0.5.
Conclusions: Significant correlation of cardiac output values was observed between the impedance cardiography and intermittent thermodilution techniques during intra-aortic balloon counterpulsation. Noninvasive evaluation of hemodynamic indices by continuous monitoring of impedance cardiography during acute myocardial infarction, complicated by cardiogenic shock and managed by intra-aortic balloon counterpulsation is a reliable method for further application.