Noninvasive approach to follow-up hemodynamics in patients with intra-aortic balloon counterpulsation: expediency and value

Introduction

Evaluation of hemodynamics in patients with complicated acute myocardial infarction (AMI) is crucial. Intra-aortic balloon counterpulsation (IABC) in patients with AMI complicated by cardiogenic shock (CS) is supposed to be monitored exclusively by invasive methods for assessment of hemodynamics. However, noninvasive methods might have a place in monitoring these patients.

Objective

To evaluate hemodynamic indices (HI) by intermittent thermodilution (ITD) in patients with AMI, complicated by CS managed with IABC, and to compare with HI evaluated by continuous impedance cardiography (ICG).

Methods

Cardiac output (CO) and stroke volume (SV) were measured by both ITD and ICG methods for patients with AMI complicated by CS, admitted within 12 hours from the onset of pain and managed by IABC. The standard eight-electrode ICG registration was used. The average values of COICG and SVICG derived from the last 10 min of the ICG record (60 SV instantaneous readings) were used to compare the results of ITD. Fourteen patients were investigated according to the study protocol, eight (57.1%) men and six (42.9%) women. The average age was 72.8 ± 6.9 years. Anterior AMI was diagnosed for nine (64.3%) patients, inferior for four (28.6%), circular for one (7.1%) patient. Primary PTCA was successfully performed for seven (50%) patients, six (42.9%) underwent cardiac surgery within the first 2 weeks, and primary PTCA was unsuccessful for one (7.1%) patient, who died within the first 18 hours. The mortality rate was 78.6% (11 patients).

Results

The measured COITD ranged from 2.8 ± 1.3 to 3.9 ± 1.1 l/min, SVITD from 26.8 ± 8.2 to 34.4 ± 10.8 ml. While the COICG ranged from 4.2 ± 1.4 to 4.9 ± 2.2 l/min, the SVICG ranged from 40.4 ± 14.2 to 51.4 ± 12.1 ml. The correlation coefficient (CF) was calculated comparing CO values derived from ICG and ITD; it ranged from 0.24 to 0.98 in separate patients. A weak correlation of ICG and ITD measurements was observed before initiation of IABC – 0.24–0.27 in separate cases. CF improved during IABC (0.58–0.98) and at the termination of IABC (0.67–0.97). The observed correlation was more pronounced in patients without a high dose of inotropes and ranged 0.58–0.98 while for patients with a high dose of inotropes it was less pronounced (0.29–0.5).

Conclusion

Significant correlation of SV was observed between the ICG and ITD methods during IABC. However, higher values of CO and SV were measured by ICG. Non-invasive evaluation of hemodynamic indices by continuous monitoring of ICG during AMI, complicated by CS and managed by IABC, is a reliable method for further application. The correlation of hemodynamic parameters measured by two methods was more pronounced in patients without a high dose of inotropes.