Hemodynamic determinants and ventriculo-arterial coupling are sex-associated in heart failure patients

The Impact of Chemotherapy on Arterial Stiffness and Ventricular-Arterial Coupling in Women with Breast Cancer

BACKGROUND

The cardiac toxicity of chemotherapy for breast cancer is not uncommon and has been associated with elevated morbidity and mortality. In the present study, we assessed the impact of chemotherapy on cardiovascular function by assessing the cardio-ankle vascular index (CAVI), global longitudinal strain (GLS) and ventricular-arterial coupling (VAC: CAVI/GLS ratio) in chemotherapy-treated women.

METHODS

This prospective study enrolled 78 women with breast cancer who were receiving anthracycline-based chemotherapy +/- anti-HER2 therapy (trastuzumab +/- pertuzumab). Forty-one age-matched healthy women served as controls. We comparatively evaluated left ventricular ejection fraction (LVEF), CAVI, GLS and VAC, between the chemotherapy and control groups. We also assessed their changes over time (baseline, 3-month and 6-month time point) and their independent association with the incidence of cancer therapy-related cardiovascular dysfunction (CTRCD) in the chemotherapy group.

RESULTS

In comparison to healthy controls, women receiving chemotherapy presented with significantly higher GLS (from -21.02 ± 2.09% to -19.01 ± 2.81%, p < 0.001) and VAC (-0.36 ± 0.06 to -0.41 ± 0.11, p < 0.001). The presence of CTRCD was associated with a further increase in GLS and CAVI and a significant decline in LVEF and VAC compared to CTRCD-free women (p < 0.001). Baseline, CAVI, GLS and VAC were independently associated with CTRCD development during follow-up.

CONCLUSION

Women with breast cancer undergoing chemotherapy displayed abnormal levels of CAVI, VAC and GLS, compared to healthy individuals. Those effects on VAC and CAVI were more exaggerated among women with CTRCD, implicating their potential use to refine screening and therapeutic strategies for this specific population.

Valvulo-Arterial Impedance and Dimensionless Index for Risk Stratifying Patients With Severe Aortic Stenosis

The hemodynamic effects of aortic stenosis (AS) consist of increased left ventricular (LV) afterload, reduced myocardial compliance, and increased myocardial workload. The LV in AS patients faces a double load: valvular and arterial loads. As such, the presence of symptoms and occurrence of adverse events in AS should better correlate with calculating the global burden faced by the LV in addition to the transvalvular gradient and aortic valve area (AVA). The valvulo-arterial impedance (Zva) is a useful parameter providing an estimate of the global LV hemodynamic load that results from the summation of the valvular and vascular loads. In addition to calculating the global LV afterload, it is paramount to estimate the stenosis severity accurately. In clinical practice, the management of low-flow low-gradient (LF-LG) severe AS with preserved LV ejection fraction requires careful confirmation of stenosis severity. In addition to the Zva, the dimensionless index (DI) is a very useful parameter to express the size of the effective valvular area as a proportion of the cross-section area of the left ventricular outlet tract velocity-time integral (LVOT-VTI) to that of the aortic valve jet (dimensionless velocity ratio). The DI is calculated by a ratio of the sub-valvular velocity obtained by pulsed-wave Doppler (LVOT-VTI) divided by the maximum velocity obtained by continuous-wave Doppler across the aortic valve (AV-VTI). In contrast to AVA measurement, the DI does not require the calculation of LVOT cross-sectional area, a major cause of erroneous assessment and underestimation of AVA. Hence, among patients with LG severe AS and preserved LV ejection fraction, calculation of DI in routine echocardiographic practice may be useful to identify a subgroup of patients at higher risk of mortality who may derive benefit from aortic valve replacement. This article aims to elucidate the Zva and DI in different clinical situations, correlate with the standard indexes of AS severity, LV geometry, and function, and thus prove to improve risk stratification and clinical decision making in patients with severe AS.

Microstructure of the juvenile sheep aortic valve hinge region and the trilamellar sliding hypothesis

Background: The aortic valve mechanism performs extremely sophisticated functions which depend on the microstructure of its component parts. The hinge mechanism of the aortic leaflets plays a crucial part in the overall function. However, the detailed microstructure and its relation to function has not been adequately studied.

Methods: The aortic roots of juvenile sheep were fixed under physiologic pressure. Sections through all three sinuses were then performed to illustrate the microstructure of the hinge mechanism in different regions of the aortic root.

Results: The hinge region in the different sinuses showed unique microstructure with a trilamellar topology with a dominant core consisting of glycosaminoglycans. The exact arrangement of the trilamellar structures varies around the aortic sinuses, which could have functional implications. These features allow the hinge to perform its complex functions through what we have described as “the trilamellar sliding hypothesis”.

Conclusion: The microstructure of the hinge mechanism is unique and enables it to perform it sophisticated functions.

Heart Failure Phenotypes Require Sex-Specific Criteria Which Are Based on Ventricular Dimensions

Ejection fraction (EF) is often used as a criterion to establish diagnostic phenotypes of heart failure (HF). Because EF is a derived metric based on end-systolic volume (ESV) and end-diastolic volume (EDV), it is more logical to consider ESV or EDV as cut-off marker. We concentrate on the impact of ESV, which has the advantage of being linearly related to EDV and nonlinearly with EF, both with highly significant correlations. In particular we also analyze if HF classification should distinguish between females and males.ESV and EDV were determined by biplane angiography in 197 HF patients (67 women). As body surface indexed (i) ESVi values for adult healthy females are smaller than for males, we employ classes of ESVi (bins of 10 mL/m²) to group preserved and reduced EF's (cut-off at 50%) for HF. Reference values regarding mean and standard deviation for ESVi are based on a control group (N=155, 65 women) without HF. For interpretation of the findings we use the documented universal relationship connecting EF to ESV: EF = 1 + c₁ {ESV / (c₂ - ESV)}, where c₁ and c₂ are population-based sex-independent constants. In the reference group ESVi (mL/m²) in women (27.4 ± 27.6) is smaller (P=0.0026) than in their male counterparts (43.6 ± 37.5). Similarly, for HF the ESVi in women (45.7 ± 41.4) is smaller (P=0.0033) than in men (64.2 ± 41.4). This signifies (see formula above) that women have higher values for EF, primarily resulting from smaller ventricular size related to their sex, and not exclusively reflecting disease state. Current phenotype classification based on pooled data for males and females may be inappropriate for either sex.The significantly smaller ESVi observed in women has direct consequences for the traditional classification based on EF cutoff values for HF. Sex-specific criteria (regarding ESVi or EF) for HF phenotypes are warranted, and expectedly have substantial consequences for identification, classification, and management of HF patients.

Arterial Wall Properties in Men and Women: Hemodynamic Analysis and Clinical Implications

The properties of arterial walls are dictated by their underlying structure, which is responsible for the adequate perfusion of conduit branching arteries and their vascular beds. Beginning with the mechanobiology of arteries in terms of their composition and individual contributions to overall viscoelastic behavior in men and women, pressure-flow relations are analyzed and noted in terms of sex differences. Hemodynamic function in terms of indices of vascular stiffness-such as pressure-strain elastic modulus, pulse wave velocity, augmentation index, and cardio-ankle vascular index-are evaluated. They all showed differences between the sexes, and these differences also were shown among people of different cultures. Recent studies also showed, in heart failure patients, a comparatively greater increase in peripheral resistance and a greater decreased arterial compliance in women. Wave separation into forward and reflected waves allows elucidation of mechanical and drug-treated similarities and differences in induced hypertension. This may provide insight into treatment strategy in terms of improving mechanobiology and designing drug therapy for the sexes. Finally, modeling studies are useful in identifying how arterial compliance and its pressure dependence can be better used in differentiating aging- and hypertension-induced changes that differentially affect the sexes.

Sex- and Age-Related Reference Values in Cardiology, with Annotations and Guidelines for Interpretation

The definition of "abnormal" in clinical sciences is often based on so-called reference values which point to a range that experts by some sort of consensus consider as normal when looking at biological variables. Such a level is commonly calculated by taking (twice) the standard deviation from the mean, or considering certain percentiles. The suspicion or even confirmation of a disease is then established by demonstrating that the value measured exceeds the upper or lower reference value. As is often the case, the measurement accuracy may depend on the conditions and specific method employed to collect and analyze data. This implies that, for example, data assessed by 2D echocardiography possibly differ from those obtained by MRI and therefore require modality-specific reference values. In this review we summarize reference values for the electrocardiogram, cardiac compartmental volumes, and arterial vessel size in males and females for various age groups. These values may further depend on other variables such as body size, physical training status, and ethnicity. Additional variables relevant for cardiology such as those referring to the microcirculation and biomarkers are only mentioned with reference to the pertinent literature. In general, the sex- and age-specific differences observed are often remarkable and warrant consideration in clinical practice and basic biomedical sciences.

Cardiophysiology Illustrated by Comparing Ventricular Volumes in Healthy Adult Males and Females

Recent advances in cardiac imaging techniques have substantially contributed to a growing interest in the analysis of global cardiac chamber dimensions and regional myocardial deformation. During the cardiac cycle, ventricular luminal volume varies due to the contraction process, which also confers a shape change including substantial alteration of long axis length, as well as rotation of the base compared to the apex. Local deformation can be assessed by strain (rate) analysis. Reviewing the present literature, it must be concluded that there is no single metric available to comprehensively characterize ventricular function. Every candidate advanced thus far has been found to incompletely reflect ventricular performance. This observation is not surprising in view of the complexity of the cardiac pump system. Additionally, sex-specific modifiers may play a role. More than three decades ago, it was shown that on average the ventricular volume is smaller in healthy women compared to matched males. Therefore, the present contribution concerns the interpretation of data derived from the healthy heart in both men and women. Starting from the classical Starling concept, we apply a simple mathematical transformation which permits an insightful representation of ventricular mechanics. Relating end-systolic volume (ESV) to end-diastolic volume creates the ventricular volume regulation graph which features the pertinent working point of an individual heart. This fundamental approach illustrates why certain proposed performance indexes cannot individually reveal the essence of ventricular systolic function. We demonstrate that particular metrics are highly interconnected and just tell us the same story in a different disguise. It is imperative to understand which associations exist and if they expectedly are (nearly) linear or frankly nonlinear. Notably, ejection fraction (EF) is primarily determined by ESV, while in turn EF is not much different from ventriculo-arterial coupling (VAC). Insight into cardiac function is promoted by identification of the paramount/essential components involved. The smaller ESV (p < 0.0001) implies that EF is higher in women and may also have consequences for VAC.