Role of Neurohormonal Modulators in Heart Failure with Relatively Preserved Systolic Function

Perioperative Diastolic Dysfunction

Left ventricular diastolic dysfunction (LVDD) has only recently been recognized as an important determinant of perioperative morbidity. Intraoperative echocardiographers have been slow to adopt assessment of LVDD into clinical practice. This has been partly attributable to the complex measurements required to characterize LVDD, which are in turn related to how our understanding of diastole has evolved. Additionally, the lack of effective therapeutic options has left many wondering whether it is worthwhile to characterize this pathology in the first place. However, therapies are developed more rapidly once a problem can be identified reliably. The assessment of LVDD is centered on how effectively the left ventricle can fill. Diastolic dysfunction affects intraventricular pressures and stiffness, which in turn affect the pressure relationship between the left atrium and the left ventricle thereby affecting transmitral flow. Since echocardiography can enable the measurement of flow velocities, transmitral diastolic filling flow patterns provide robust information on diastolic function. The impact of abnormal diastolic function on left atrial pressure has consequences for pulmonary venous flow, which can also be measured with echocardiography. However, given the limitations of flow velocity, direct measurement of tissue velocity can significantly improve the characterization of diastolic dysfunction. The evolution of Doppler and speckle-based methods of assessing tissue motion have vastly improved our understanding of diastolic function. With the development of simpler algorithms for categorization, and their gradual adoption by perioperative echocardiographers, LVDD should be better diagnosed and treated to improve postoperative outcomes.

Update on diastolic heart failure or heart failure with preserved ejection fraction in the older adults

Nearly half of all heart failure (HF) patients have diastolic HF (DHF) or clinical HF with normal or near-normal left ventricular ejection fraction (LVEF). Although the terminology has not been clearly defined, it is increasingly being referred to as HF with preserved ejection fraction (HFPEF). The prevalence of HFPEF increases with age, especially among older women. Identifying HFPEF is important because the etiology, pathogenesis, prognosis, and optimal management may differ from that for systolic HF (SHF) or HF with reduced ejection fraction. The clinical presentation of HF is similar for both SHF and HFPEF. As in SHF, HFPEF is a clinical diagnosis. Once a clinical diagnosis of HF has been made, the presence of HFPEF can be established by confirming a normal or near-normal LVEF, often by an echocardiogram. HFPEF is often associated with a history of hypertension, concentric left ventricular hypertrophy, vascular stiffness, and left ventricular diastolic dysfunction. As in SHF, HFPEF is also associated with poor outcomes. While therapies with angiotensin-converting enzyme inhibitors and beta-blockers improve outcomes in SHF, there is currently no such evidence of their benefits in older HFPEF patients. In this review recent advances in the diagnosis and management of HFPEF in older adults are discussed.

Therapeutic approaches to diastolic dysfunction

Progressive abnormalities of passive stiffness or active relaxation of the myocardium that impair ventricular filling during diastole may be an important contributor to the development of heart failure in patients with preserved ejection fraction. In this review, we discuss the epidemiology and pathophysiology of diastolic dysfunction and heart failure with preserved ejection fraction, highlighting potential therapeutic approaches and exploring the limited available evidence base for improving clinical outcomes in patients with these challenging entities.

Genetic polymorphisms of the angiotensin II type 1 receptor gene and diastolic heart failure

OBJECTIVES

The aim of the study was to investigate the association between angiotensin II type 1 receptor (AGTR1) gene polymorphisms and diastolic heart failure (DHF) in a case controlled study.

METHODS

Of 1752 consecutive patients analyzed, 176 diagnosed with DHF and confirmed by echocardiography were recruited. Controls were matched one-to-one by age, sex, hypertension, diabetes, renal function, and medication use. We genotyped 11 single nucleotide polymorphisms (SNPs) according to the HapMap Han Chinese Beijing databank across the AGTR1 gene to capture 96% of the haplotype variance in all SNPs with minor allele frequencies at least 5%. We also genotyped A1166C (rs5186) SNP with known associations with cardiovascular disease and analyzed associations of SNPs and haplotypes with DHF and linkage disequilibrium structure of the AGTR1 gene.

RESULTS

In a single locus analysis, SNP rs16860760, rs389566, and rs5186 were associated with DHF (allele specific P = 0.004, 0.002, 0.002, respectively; permuted P = 0.045, 0.022, 0.027, respectively). SNP rs389566, with a minor allele frequency of 20.17%, had an odds ratio (OR) 2.03 for the autosomal dominant model [AA + AT: TT, 95% confidence interval (CI) 1.29-3.19; P = 0.0012] and 1.73 for the additive model (95% CI 1.21-2.48; P = 0.0018) corresponding to a population attributable risk fraction of 27.21%. The haplotypes in a linkage disequilibrium block of rs389566 (T-A-G and A-A-G) were also significantly associated with DHF (permuted P = 0.0125 and 0.0105, respectively).

CONCLUSION

We identified risk-conferring genetic variants of the AGTR1 gene for DHF in a Chinese population.

Renin-angiotensin system gene polymorphisms and diastolic heart failure

BACKGROUND

Diastolic heart failure (DHF) refers to an abnormality of diastolic distensibility, filling or relaxation of the left ventricle. The genetic study of DHF is scarce in the literature. The association of renin-angiotensin system (RAS) and DHF are well known. We hypothesized that RAS genes might be the susceptible genes for DHF and conducted a case-control study to prove the hypothesis.

MATERIALS AND METHODS

A total of 1452 consecutive patients were analysed and 148 patients with a diagnosis of DHF confirmed by echocardiography were recruited. We had two control populations. The first controls consisted of 286 normal subjects while the second were 148 matched controls selected on a 1-to-1 basis by age, sex, hypertension, diabetes and medication use. The angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism; multilocus polymorphisms of the angiotensinogen gene; and the A1166C polymorphisms of the angiotensin II type I receptor (AT(1)R) gene were genotyped.

RESULTS

In a single-locus analysis, the odds ratios (ORs) for DHF were significant with the ACE DD genotype and the AT(1)R 1166 CC plus AC genotype. In addition, the concomitant presence of ACE DD and AT(1)R 1166 CC/AC genotypes synergistically increased the predisposition to DHF.

CONCLUSIONS

Genetic variants in the RAS genes may determine an individual's risk to develop DHF. There is also a synergistic gene-gene interaction between the RAS genes in the development of DHF.

Treatment of hypertension in heart failure with preserved ejection fraction: role of the kidney

Heart failure can present clinically as primarily diastolic or systolic dysfunction or both. There is an increasing awareness that heart failure can occur in the presence of a normal left ventricular ejection fraction. Heart failure with normal left ventricular ejection fraction is frequently referred to as diastolic heart failure because of the presence of diastolic left ventricular dysfunction evident from impaired left ventricular relaxation. This article focuses on the treatment of hypertension and the role the kidney plays in selecting appropriate agents.