Graphical Description of Left Ventricular Volumetric Characteristics in Selected Chronic Inflammatory Diseases

Abstract

The combination of heart rate and stroke volume (SV) indexed (i) to body size provides an indication of adequacy of tissue blood perfusion. Both arterial compliance (AC) and arterial elastance (Ea) depend on SV. Understanding how pump function is performed requires determination of the prevailing working point of the heart. In practice we can look at end‐systolic volume (ESV) which is a key element in the characterization of ventricular functioning. Considering SV and ESV in unison offers a logical framework to study the cardiovascular system (Figure 1). This strategy allows the creation of two ratio‐based metrics: i) (SV/ESV) which is usually referred to as ventriculo‐arterial coupling (VAC) while assuming that the volume intercept vanishes, and ii) {SV/(ESV + SV)} which is known as ejection fraction (EF). As a consequence the EF and VAC are nonlinearly related, meaning that depending on the asymptotic region considered, one or the other is a more sensitive indicator. Being dimensionless ratios, EF and VAC do not consider body size.We retrospectively investigate the SV to ESV relationship in various diagnostic groups of patients (informed consent obtained), and calculated derived metrics. ESV and SV were determined in 145 patients (77% women) by echocardiography in Almazov National Medical Research Centre (Saint‐Petersburg). We created graphs of SV vs ESV to provide insight into VAC and EF differences in the following groups: scleroderma (Sc, N=55) and rheumatoid arthritis (RA, N=28) compared to atherosclerosis (Ath, N=62).Figure 2 shows data points for SV vs ESV in these 3 groups. SV is higher (P<0.0001) in Ath (69.6±12.3 mL) than in Sc (59.4±13.5 mL) or (P=0.01) in RA (61.8±16.0 mL), while ESV is only larger (P=0.0003) in RA (36.9±9.7 mL) than in Ath (30.3±6.8 mL). For the resulting ratio‐based metrics VAC is higher (P<0.0001) in Ath (2.35±0.36) compared to Sc (1.86±0.36) and RA (1.71±0.34), while EF is also higher (P<0.0001) in Ath (69.7±4.1) compared to Sc (64.4±4.8) and RA (62.5±5.2). Figure 2 clearly illustrates that VACC varies while VAC remains constant. The same observation obviously applies to EFC at any fixed level of EF.We conclude that EF, VAC, AC and Ea do not uniquely characterize properties of the cardiovascular system. Associated companion metrics (as proposed in Figure 1) are required to explore hemodynamic differences between various diagnostic groups in chronic inflammatory diseases. Such an extended analysis may contribute to enhanced insight into hemodynamics and connection with various pertinent biomarkers.Support or Funding InformationRussian Science Foundation (project No. 17‐15‐01177)Stroke volume (SV) versus end‐systolic volume (ESV) minus volume intercept (Vo). Ventriculo‐arterial coupling (VAC) corresponds with the slope, while the hypotenuse (c) refers to the companion associated with VAC.Figure 1Stroke volume (SV) versus end‐systolic volume (ESV), assuming that the volume intercept (Vo) vanishes. Ventriculo‐arterial coupling (VAC) is the ratio of SV and ESV.Figure 2