Pulsatile hemodynamic effects of candesartan in patients with chronic heart failure: the CHARM Program

Coarctation of the Aorta: Modern Paradigms Across the Lifespan

While coarctation of the aorta varies greatly in both severity and age at presentation, all patients are at increased risk of hypertension both before and after repair. Despite advances in knowledge about genetic etiologies, pathophysiologic mechanisms, and optimal repair strategies, patients with repaired coarctation of the aorta remain at increased risk of acquired cardiovascular disease. The aims of this review are to describe the management of coarctation of the aorta at all ages before and after repair, highlight pathophysiologic mechanisms of hypertension, and review long-term follow-up considerations.

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system for chronic heart failure with preserved ejection fraction

BACKGROUND

Beta-blockers and inhibitors of the renin-angiotensin-aldosterone system improve survival and reduce morbidity in people with heart failure with reduced left ventricular ejection fraction (LVEF); a review of the evidence is required to determine whether these treatments are beneficial for people with heart failure with preserved ejection fraction (HFpEF).

OBJECTIVES

To assess the effects of beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, angiotensin receptor neprilysin inhibitors, and mineralocorticoid receptor antagonists in people with HFpEF.

SEARCH METHODS

We updated searches of CENTRAL, MEDLINE, Embase, and one clinical trial register on 14 May 2020 to identify eligible studies, with no language or date restrictions. We checked references from trial reports and review articles for additional studies.  SELECTION CRITERIA: We included randomised controlled trials with a parallel group design, enrolling adults with HFpEF, defined by LVEF greater than 40%.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 41 randomised controlled trials (231 reports), totalling 23,492 participants across all comparisons. The risk of bias was frequently unclear and only five studies had a low risk of bias in all domains. Beta-blockers (BBs) We included 10 studies (3087 participants) investigating BBs. Five studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 30 years to 81 years. A possible reduction in cardiovascular mortality was observed (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.62 to 0.99; number needed to treat for an additional benefit (NNTB) 25; 1046 participants; three studies), however, the certainty of evidence was low. There may be little to no effect on all-cause mortality (RR 0.82, 95% CI 0.67 to 1.00; 1105 participants; four studies; low-certainty evidence). The effects on heart failure hospitalisation, hyperkalaemia, and quality of life remain uncertain. Mineralocorticoid receptor antagonists (MRAs) We included 13 studies (4459 participants) investigating MRA. Eight studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 54.5 to 80 years. Pooled analysis indicated that MRA treatment probably reduces heart failure hospitalisation (RR 0.82, 95% CI 0.69 to 0.98; NNTB = 41; 3714 participants; three studies; moderate-certainty evidence). However, MRA treatment probably has little or no effect on all-cause mortality (RR 0.91, 95% CI 0.78 to 1.06; 4207 participants; five studies; moderate-certainty evidence) and cardiovascular mortality (RR 0.90, 95% CI 0.74 to 1.11; 4070 participants; three studies; moderate-certainty evidence). MRA treatment may have little or no effect on quality of life measures (mean difference (MD) 0.84, 95% CI -2.30 to 3.98; 511 participants; three studies; low-certainty evidence). MRA treatment was associated with a higher risk of hyperkalaemia (RR 2.11, 95% CI 1.77 to 2.51; number needed to treat for an additional harmful outcome (NNTH) = 11; 4291 participants; six studies; high-certainty evidence). Angiotensin-converting enzyme inhibitors (ACEIs) We included eight studies (2061 participants) investigating ACEIs. Three studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 70 to 82 years. Pooled analyses with moderate-certainty evidence suggest that ACEI treatment likely has little or no effect on cardiovascular mortality (RR 0.93, 95% CI 0.61 to 1.42; 945 participants; two studies), all-cause mortality (RR 1.04, 95% CI 0.75 to 1.45; 1187 participants; five studies) and heart failure hospitalisation (RR 0.86, 95% CI 0.64 to 1.15; 1019 participants; three studies), and may result in little or no effect on the quality of life (MD -0.09, 95% CI -3.66 to 3.48; 154 participants; two studies; low-certainty evidence). The effects on hyperkalaemia remain uncertain. Angiotensin receptor blockers (ARBs) Eight studies (8755 participants) investigating ARBs were included. Five studies used a placebo comparator and in three the comparator was usual care. The mean age of participants ranged from 61 to 75 years. Pooled analyses with high certainty of evidence suggest that ARB treatment has little or no effect on cardiovascular mortality (RR 1.02, 95% 0.90 to 1.14; 7254 participants; three studies), all-cause mortality (RR 1.01, 95% CI 0.92 to 1.11; 7964 participants; four studies), heart failure hospitalisation (RR 0.92, 95% CI 0.83 to 1.02; 7254 participants; three studies), and quality of life (MD 0.41, 95% CI -0.86 to 1.67; 3117 participants; three studies). ARB was associated with a higher risk of hyperkalaemia (RR 1.88, 95% CI 1.07 to 3.33; 7148 participants; two studies; high-certainty evidence). Angiotensin receptor neprilysin inhibitors (ARNIs) Three studies (7702 participants) investigating ARNIs were included. Two studies used ARBs as the comparator and one used standardised medical therapy, based on participants' established treatments at enrolment. The mean age of participants ranged from 71 to 73 years. Results suggest that ARNIs may have little or no effect on cardiovascular mortality (RR 0.96, 95% CI 0.79 to 1.15; 4796 participants; one study; moderate-certainty evidence), all-cause mortality (RR 0.97, 95% CI 0.84 to 1.11; 7663 participants; three studies; high-certainty evidence), or quality of life (high-certainty evidence). However, ARNI treatment may result in a slight reduction in heart failure hospitalisation, compared to usual care (RR 0.89, 95% CI 0.80 to 1.00; 7362 participants; two studies; moderate-certainty evidence). ARNI treatment was associated with a reduced risk of hyperkalaemia compared with valsartan (RR 0.88, 95% CI 0.77 to 1.01; 5054 participants; two studies; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

There is evidence that MRA and ARNI treatment in HFpEF probably reduces heart failure hospitalisation but probably has little or no effect on cardiovascular mortality and quality of life. BB treatment may reduce the risk of cardiovascular mortality, however, further trials are needed. The current evidence for BBs, ACEIs, and ARBs is limited and does not support their use in HFpEF in the absence of an alternative indication. Although MRAs and ARNIs are probably effective at reducing the risk of heart failure hospitalisation, the treatment effect sizes are modest. There is a need for improved approaches to patient stratification to identify the subgroup of patients who are most likely to benefit from MRAs and ARNIs, as well as for an improved understanding of disease biology, and for new therapeutic approaches.

Vascular effects of combined enriched Korean Red ginseng (Panax Ginseng) and American ginseng (Panax Quinquefolius) administration in individuals with hypertension and type 2 diabetes: A randomized controlled trial

BACKGROUND

Type 2 diabetes is known to abrogate the vascular response. Combination of two commonly consumed ginseng species, American ginseng (AG) and a Korean Red ginseng (KRG), enriched with ginsensoide Rg3, was shown to concomitantly improve glucemic control and blood pressure. We evaluated the hypothesis that improvements in central hemodynamics, vascular function and stiffness markers are involved in observed benefits of co-administration.

METHODS

In this randomized, placebo controlled, two-center trial, patients with type 2 diabetes and hypertension were assigned to either 2.25 g ginsenoside Rg3-enriched KRG&AG co-administration or a control 3 times daily for 12-weeks, treated by standard of care. The effects on central hemodynamics, pulse wave velocity (PWV) and endothelial function over the 12-week administration were analyzed.

RESULTS

In intent-to-treat analysis of 80 individuals, a reduction in central systolic BP (-4.69 ± 2.24 mmHg, p = 0.04) was observed with co-administration of Rg3-KRG + AG relative to control at 12-weeks, which was characterized by a decrease in end-systolic pressure (-6.60 ± 2.5 mmHg, p = 0.01) and area under the systolic/diastolic BP curve (-132.80 ± 65.1, p = 0.04, 220.90 ± 91.1, p = 0.02, respectively). There was no significant change in reactive hyperemia index (0.09 ± 0.11, p = 0.44), PWV (-0.40 ± 0.28 %, p = 0.17), and other related pulse wave analysis components.

CONCLUSION

Co-administration of complementary ginseng species improved central systolic BP and components of pulse waveform without a direct effect on endothelial function, when added to background pharmacotherapy in individuals with diabetes. These data support potential utility of ginseng for modest blood pressure benefit to broaden its role in diabetes management.

Effect of Sacubitril-Valsartan vs Enalapril on Aortic Stiffness in Patients With Heart Failure and Reduced Ejection Fraction: A Randomized Clinical Trial

IMPORTANCE

Compared with enalapril, sacubitril-valsartan reduces cardiovascular mortality and heart failure hospitalization in patients with heart failure and reduced ejection fraction (HFrEF). These benefits may be related to effects on hemodynamics and cardiac remodeling.

OBJECTIVE

To determine whether treatment of HFrEF with sacubitril-valsartan improves central aortic stiffness and cardiac remodeling compared with enalapril.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, double-blind clinical trial of 464 participants with heart failure and ejection fraction of 40% or less enrolled across 85 US sites between August 17, 2016, and June 28, 2018. Follow-up was completed on January 26, 2019.

INTERVENTIONS

Randomization (1:1) to sacubitril-valsartan (n = 231; target dosage, 97/103 mg twice daily) vs enalapril (n = 233; target dosage, 10 mg twice daily) for 12 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcome was change from baseline to week 12 in aortic characteristic impedance (Zc), a measure of central aortic stiffness. Prespecified secondary outcomes included change from baseline to week 12 in N-terminal pro-B-type natriuretic peptide, ejection fraction, global longitudinal strain, mitral annular relaxation velocity, mitral E/e' ratio, left ventricular end-systolic and end-diastolic volume indexes (LVESVI and LVEDVI), left atrial volume index, and ventricular-vascular coupling ratio.

RESULTS

Of 464 validly randomized participants (mean age, 67.3 [SD, 9.1] years; 23.5% women), 427 completed the study. At 12 weeks, Zc decreased from 223.8 to 218.9 dyne × s/cm5 in the sacubitril-valsartan group and increased from 213.2 to 214.4 dyne × s/cm5 in the enalapril group (treatment difference, -2.2 [95% CI, -17.6 to 13.2] dyne × s/cm5; P = .78). Of 9 prespecified secondary end points, no significant between-group difference in change from baseline was seen in 4, including left ventricular ejection fraction (34%-36% with sacubitril-valsartan vs 33 to 35% with enalapril; treatment difference, 0.6% [95% CI, -0.4% to 1.7%]; P = .24). However, greater reductions from baseline were seen with sacubitril-valsartan than with enalapril in all others, including left atrial volume (from 30.4 mL/m2 to 28.2 mL/m2 vs from 29.8 mL/m2 to 30.5 mL/m2; treatment difference, -2.8 mL/m2 [95% CI, -4.0 to -1.6 mL/m2]; P < .001), LVEDVI (from 75.1 mL/m2 to 70.3 mL/m2 vs from 79.1 mL/m2 to 75.6 mL/m2; treatment difference, -2.0 mL/m2 [95% CI, -3.7 to 0.3 mL/m2]; P = .02), LVESVI (from 50.8 mL/m2 to 46.3 mL/m2 vs from 54.1 to 50.6 mL/m2; treatment difference, -1.6 mL/m2 [95% CI, -3.1 to -0.03 mL/m2]; P = .045), and mitral E/e' ratio (from 13.8 to 12.3 vs from 13.4 to 13.8; treatment difference, -1.8 [95% CI, -2.8 to -0.8]; P = .001). Rates of adverse events including hypotension (1.7% vs 3.9%) were similar in both groups.

CONCLUSIONS AND RELEVANCE

Treatment of HFrEF with sacubitril-valsartan, compared with enalapril, did not significantly reduce central aortic stiffness. The study findings may provide insight into mechanisms underlying the effects of sacubitril-valsartan in HFrEF.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02874794.

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system for chronic heart failure with preserved ejection fraction

BACKGROUND

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system improve survival and reduce morbidity in people with heart failure with reduced left ventricular ejection fraction. There is uncertainty whether these treatments are beneficial for people with heart failure with preserved ejection fraction and a comprehensive review of the evidence is required.

OBJECTIVES

To assess the effects of beta-blockers, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, angiotensin receptor neprilysin inhibitors, and mineralocorticoid receptor antagonists in people with heart failure with preserved ejection fraction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and two clinical trial registries on 25 July 2017 to identify eligible studies. Reference lists from primary studies and review articles were checked for additional studies. There were no language or date restrictions.

SELECTION CRITERIA

We included randomised controlled trials with a parallel group design enrolling adult participants with heart failure with preserved ejection fraction, defined by a left ventricular ejection fraction of greater than 40 percent.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion and extracted data. The outcomes assessed included cardiovascular mortality, heart failure hospitalisation, hyperkalaemia, all-cause mortality and quality of life. Risk ratios (RR) and, where possible, hazard ratios (HR) were calculated for dichotomous outcomes. For continuous data, mean difference (MD) or standardised mean difference (SMD) were calculated. We contacted trialists where neccessary to obtain missing data.

MAIN RESULTS

37 randomised controlled trials (207 reports) were included across all comparisons with a total of 18,311 participants.Ten studies (3087 participants) investigating beta-blockers (BB) were included. A pooled analysis indicated a reduction in cardiovascular mortality (15% of participants in the intervention arm versus 19% in the control arm; RR 0.78; 95% confidence interval (CI) 0.62 to 0.99; number needed to treat to benefit (NNTB) 25; 1046 participants; 3 studies). However, the quality of evidence was low and no effect on cardiovascular mortality was observed when the analysis was limited to studies with a low risk of bias (RR 0.81; 95% CI 0.50 to 1.29; 643 participants; 1 study). There was no effect on all-cause mortality, heart failure hospitalisation or quality of life measures, however there is uncertainty about these effects given the limited evidence available.12 studies (4408 participants) investigating mineralocorticoid receptor antagonists (MRA) were included with the quality of evidence assessed as moderate. MRA treatment reduced heart failure hospitalisation (11% of participants in the intervention arm versus 14% in the control arm; RR 0.82; 95% CI 0.69 to 0.98; NNTB 41; 3714 participants; 3 studies; moderate-quality evidence) however, little or no effect on all-cause and cardiovascular mortality and quality of life measures was observed. MRA treatment was associated with a greater risk of hyperkalaemia (16% of participants in the intervention group versus 8% in the control group; RR 2.11; 95% CI 1.77 to 2.51; 4291 participants; 6 studies; high-quality evidence).Eight studies (2061 participants) investigating angiotensin converting enzyme inhibitors (ACEI) were included with the overall quality of evidence assessed as moderate. The evidence suggested that ACEI treatment likely has little or no effect on cardiovascular mortality, all-cause mortality, heart failure hospitalisation, or quality of life. Data for the effect of ACEI on hyperkalaemia were only available from one of the included studies.Eight studies (8755 participants) investigating angiotensin receptor blockers (ARB) were included with the overall quality of evidence assessed as high. The evidence suggested that treatment with ARB has little or no effect on cardiovascular mortality, all-cause mortality, heart failure hospitalisation, or quality of life. ARB was associated with an increased risk of hyperkalaemia (0.9% of participants in the intervention group versus 0.5% in the control group; RR 1.88; 95% CI 1.07 to 3.33; 7148 participants; 2 studies; high-quality evidence).We identified a single ongoing placebo-controlled study investigating the effect of angiotensin receptor neprilysin inhibitors (ARNI) in people with heart failure with preserved ejection fraction.

AUTHORS' CONCLUSIONS

There is evidence that MRA treatment reduces heart failure hospitalisation in heart failure with preserverd ejection fraction, however the effects on mortality related outcomes and quality of life remain unclear. The available evidence for beta-blockers, ACEI, ARB and ARNI is limited and it remains uncertain whether these treatments have a role in the treatment of HFpEF in the absence of an alternative indication for their use. This comprehensive review highlights a persistent gap in the evidence that is currently being addressed through several large ongoing clinical trials.

Associations of Alterations in Pulsatile Arterial Load With Left Ventricular Longitudinal Strain

BACKGROUND

Increased arterial stiffness leads to increased pulsatile load on the heart. We investigated associations of components of pulsatile load with a measure of left ventricular (LV) systolic function-global longitudinal strain (GLS), in a community-based cohort ascertained based on family history of hypertension.

METHODS

Arterial tonometry and echocardiography with speckle tracking were performed in 520 adults with normal LV ejection fraction (EF) (age 67±9 years, 70% hypertensive) to quantify measures of pulsatile load (characteristic aortic impedance (Zc), total arterial compliance (TAC), and augmentation index (AI)) and GLS. The associations of log-Zc, log-TAC, and AI with GLS were assessed using sex-specific z-scores for each measure of arterial load.

RESULTS

In univariable analyses, higher Zc was associated with worse GLS (less negative) and higher TAC and AI were associated with better GLS (all P < 0.001). In a multivariable model including age, sex, heart rate (HR), LVEF, mean arterial load (systemic vascular resistance), and measures of pulsatile load, Zc remained associated with GLS (β = 0.28, P < 0.001), while the associations of TAC and AI were no longer significant (P > 0.5). Additional adjustment for cardiovascular risk factors and history of coronary heart disease and stroke did not attenuate the association of Zc with GLS; Zc, sex, HR, LVEF remained associated with GLS after stepwise elimination (all P < 0.001).

CONCLUSIONS

Greater proximal aortic stiffness, as manifested by a higher Zc, is independently associated with worse LV longitudinal function.

Brachial artery tonometry and the Popeye phenomenon: explanation of anomalies in generating central from upper limb pressure waveforms

BACKGROUND

Noninvasive applanation tonometry studies of the brachial and radial artery pressure waves show that the arterial pulse is substantially amplified between the brachial and radial sites. Brachial tonometry waveforms have also been used to calibrate carotid tonometry waves as a measure of central pressure in major clinical trials. These trials assume identity of mean and of DBP in calculation of central (carotid) SBP. None of these trials showed superiority of central over brachial pressure in predicting outcome, but all showed equivalence of SBP and pulse pressure at brachial and carotid sites!

METHOD

We tested this method by measuring pressure waves at brachial, radial and carotid sites by applanation tonometry in 100 patients, with attention to any subtle difference between brachial and radial waveforms, and with both calibrated to cuff SBP and DBP.

RESULTS

The results confirmed no proximal and strong distal amplification in the arm. However, this was accompanied by blunting of the brachial compared with radial waveform with brachial pressure 2.7 mmHg higher during most of the cardiac cycle. Form factor of the ensemble-averaged brachial wave [39.1 standard deviation (SD) 4.9%] was similar to the carotid (40.2 SD 4.1%) but different to the radial wave (34.8 SD 3.7%; P < 0.01).

CONCLUSIONS

All findings were explained by inability to applanate the brachial artery, and resulting systematic error in generating brachial waveforms. In estimation of central pressure with applanation tonometry, the radial pressure wave, which can be accurately applanated, should be used, and calibrated to the brachial cuff.

Noninvasive studies of central aortic pressure

Our purpose is to review noninvasive methods for measuring central arterial pressure. Indices of central arterial pressure measured from central aortic and peripheral arterial waveforms have shown value in predicting cardiovascular events and death, as well as in guiding therapeutic management. This article reviews noninvasive techniques of measuring central arterial pressure that have been validated against intra-arterial pressure. This paper explains methods to derive central (aortic and carotid) pressure from radial and brachial sites. It focuses on specific issues of brachial calibration applied to carotid pressure waveforms, which were regarded as a surrogate of aortic pressures used in three major studies (Framingham, Asklepios, and Australian National Blood Pressure 2 studies). We explain why radial-based methods are superior to carotid-based methods for estimating central pressure. Physiological principles of pressure measurement need be satisfied to ensure accurate recording.

Vascular compliance in blood pressure

PURPOSE OF REVIEW

Vascular stiffening is a hallmark of the aging process. Improvements in the methods used to measure central stiffness, particularly applanation tonometry, and their use as therapeutic targets have generated great interest.

RECENT FINDINGS

Vascular stiffness is associated with increases in pulse pressure (PP), aortic augmentation index, and pulse wave velocity (PWV). This last has emerged as the gold standard for evaluation of vascular stiffness, as it is an independent predictor of coronary heart disease, stroke, and mortality. Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and calcium-channel blockers with or without diuretics are all commonly used to ameliorate vascular stiffness; however, selective β-1 blockers (β-blockers) may actually worsen aortic PP and aortic augmentation index.

SUMMARY

Serial measurements of vascular stiffness, including PWV, augmentation index, and PP, may be especially beneficial in older patients to supplement brachial blood pressure. At present, given the lack of universally accepted normal values for vascular stiffness as measured by applanation tonometry, serial measurements over time may be more helpful than a single isolated value. In patients with suspected vascular stiffening, therapy should include inhibition of the renin-angiotensin-aldosterone system with ACE inhibitors or ARBs, calcium-channel blockers, and diuretics as needed to normalize blood pressure. β-Blockers should be reserved for patients with a history of myocardial infarction or congestive heart disease. It remains to be established whether β-blockers with vasodilator properties could improve the assessment of vascular compliance.

Aging and arterial stiffness

Arterial walls stiffen with age. The most consistent and well-reported changes are luminal enlargement with wall thickening and a reduction of elastic properties at the level of large elastic arteries. Longstanding arterial pulsation in the central artery causes elastin fiber fatigue and fracture. Increased vascular calcification and endothelial dysfunction are also characteristic of arterial aging. These changes lead to increased pulse wave velocity, especially along central elastic arteries, and increases in systolic blood pressure and pulse pressure. Vascular aging is accelerated by coexisting cardiovascular risk factors, such as hypertension, metabolic syndrome and diabetes. Vascular aging is an independent risk factor for cardiovascular disease, from atherosclerosis to target organ damage, including coronary artery disease, stroke and heart failure. Various strategies, especially controlling hypertension, show benefit in preventing, delaying or attenuating vascular aging.

Central aortic stiffness is increased in patients with heart failure and preserved ejection fraction

BACKGROUND

Hypertension is an important risk factor for the development of heart failure with preserved ejection fraction. Although heart failure in hypertensive patients is usually ascribed to intrinsic myocardial abnormalities, noncardiac factors may contribute.

METHODS AND RESULTS

Using arterial tonometry and Doppler echocardiography, we assessed arterial stiffness and cardiac diastolic function in 53 individuals with ejection fraction >or=0.50, including 23 with hypertension but no heart failure, 16 with hypertension and heart failure, and 14 healthy, normotensive controls. Relative to healthy controls and hypertensives, subjects with heart failure had higher systolic blood pressure, body mass index, creatinine, and left ventricular mass. Diastolic function, as estimated by myocardial relaxation velocity, was not different among the 3 groups. Peripheral arterial stiffness was similar across all groups, but key measures of central aortic stiffness (carotid-femoral pulse wave velocity, characteristic impedance, forward wave amplitude) steadily increased with progression from healthy to hypertensive to heart failure despite adjustment for body mass index, systolic blood pressure, and renal function and were positively correlated with both left ventricular mass and filling pressure.

CONCLUSIONS

We conclude that patients with heart failure and preserved ejection fraction have increased central aortic stiffness relative to age-matched healthy and hypertensive subjects without heart failure. These changes exceed differences in diastolic function and suggest that abnormal ventricular-vascular coupling may contribute to the pathophysiology of heart failure with preserved ejection fraction.

Clinical achievements of impedance analysis

Various models and derived measures of arterial function have been proposed to describe and quantify pulsatile hemodynamics in humans. A major distinction can be drawn between lumped models based on circuit theory that assume infinite pulse wave velocity versus distributed, propagative models based on transmission line theory that acknowledge finite wave velocity and account for delays, wave reflection, and spatial and temporal pressure gradients within the arterial system. Although both approaches have produced useful insights into human arterial pathophysiology, there are important limitations of the lumped approach. The arterial system is heterogeneous and various segments respond differently to cardiovascular disease risk factors including advancing age. Lumping divergent change into aggregate summary variables can obscure abnormalities in regional arterial function. Analysis of a limited number of summary variables obtained by measuring aortic input impedance may provide novel insights and inform development of new treatments aimed at preventing or reversing abnormal pulsatile hemodynamics.

Heart failure with preserved ejection fraction: hypertension, diabetes, obesity/sleep apnea, and hypertrophic and infiltrative cardiomyopathy

The detailed pathophysiology of heart failure with preserved ejection fraction (HF-PEF) remains an area of active research and controversy; however, abnormalities of diastolic function are generally believed to play an important role. Most commonly, diastolic dysfunction occurs as a consequence of myocyte hypertrophy, endomyocardial fibrosis, and abnormalities of intracellular calcium handling that are related to normal myocardial aging and accelerated by comorbidities such as hypertension, diabetes, coronary artery disease, and obesity. In this article, three fundamental risk factors are considered for "secondary" diastolic dysfunction and HF-hypertension, diabetes, and obesity-with an emphasis on the clinical epidemiology, pathophysiologic mechanisms, and treatment implications of each. The article concludes with a brief discussion of "primary" diastolic HF due to infiltrative or restrictive cardiomyopathies.

Current understanding of heart failure with preserved ejection fraction

PURPOSE OF REVIEW

A substantial proportion of patients with heart failure have preserved ejection fraction. Though patients with preserved ejection fraction experience a substantial burden of morbidity and mortality, the understanding of heart failure pathophysiology in this group remains incomplete and evidence-based therapeutic options are limited.

RECENT FINDINGS

The prevalence of heart failure in patients with preserved ejection fraction is increasing and prognosis in this population remains poor despite modern medical therapy. Though diastolic dysfunction is typically present, increasing evidence suggests that extracardiac factors such as renal dysfunction and enhanced central aortic stiffness may play an important role in the development and progression of heart failure symptoms. Results of the first randomized, controlled clinical trials in this population suggest a possible therapeutic role for renin-angiotensin system blockade in reducing heart failure-associated morbidity, but there is still no evidence-supported strategy for reducing mortality in this population.

SUMMARY

Though the epidemiology and impact of heart failure with preserved ejection fraction are increasingly clear, consensus regarding pathophysiology and the optimal therapeutic approach is still lacking. Pending completion of additional therapeutic trials in this population, treatment remains largely empiric and focused on optimizing myocardial performance in diastole by control of blood pressure, restoration or maintenance of sinus rhythm, and relief of volume overload.

Drug effects on the mechanical properties of large arteries in humans

1. Arteries become stiffer with increasing age and various disease states. A complete description of arterial mechanical properties in vivo is not possible, although a number of methods have been used. 2. Detailed discussion in the present review is limited to pulse wave velocity and estimates of central waveform morphology derived by the application of a generalized arterial transfer function. 3. Many drugs affect these parameters, either increasing or decreasing apparent stiffness. However, the extent to which changes reflect changes in blood pressure rather than more fundamental vessel wall properties remains unclear. Similarly, it is as yet unknown whether determining the need for, or assessing the effectiveness of, drug treatment by the assessment of arterial mechanical properties will offer any advantage and the usefulness of these techniques as routine clinical tools remains to be established.

Long-term trandolapril treatment is associated with reduced aortic stiffness: the prevention of events with angiotensin-converting enzyme inhibition hemodynamic substudy

The Prevention of Events with Angiotensin Converting Enzyme inhibition (PEACE) trial evaluated angiotensin-converting enzyme inhibition with trandolapril versus placebo added to conventional therapy in patients with stable coronary disease and preserved left ventricular function. The PEACE hemodynamic substudy evaluated effects of trandolapril on pulsatile hemodynamics. Hemodynamic studies were performed in 300 participants from 5 PEACE centers a median of 52 months (range, 25 to 80 months) after random assignment to trandolapril at a target dose of 4 mg per day or placebo. Central pulsatile hemodynamics and carotid-femoral pulse wave velocity were assessed by using echocardiography, tonometry of the carotid and femoral arteries, and body surface transit distances. Patients randomly assigned to trandolapril tended to be older (mean+/-SD: 64.2+/-7.9 versus 62.9+/-7.7 years; P=0.14), with a higher body mass index (28.5+/-4.0 versus 27.8+/-3.9 kg/m(2); P=0.09) and lower ejection fraction (57.1+/-8.1% versus 58.7+/-8.4%; P<0.01). At the time of the hemodynamic substudy, the trandolapril group had lower mean arterial pressure (93.1+/-10.2 versus 96.3+/-11.3 mm Hg; P<0.01) and lower carotid-femoral pulse wave velocity (geometric mean [95% CI]: 10.4 m/s [10.0 to 10.9 m/s] versus 11.2 m/s [10.7 to 11.8 m/s]; P=0.02). The difference in carotid-femoral pulse wave velocity persisted (P<0.01) in an analysis that adjusted for baseline characteristics and follow-up mean pressure. In contrast, there was no difference in aortic compliance, characteristic impedance, augmentation index, or total arterial compliance. Angiotensin-converting enzyme inhibition with trandolapril produced a modest reduction in carotid-femoral pulse wave velocity, a measure of aortic wall stiffness, beyond what would be expected from blood pressure lowering or differences in baseline characteristics alone.

Quantification of wave reflection in the human aorta from pressure alone: a proof of principle

Wave reflections affect the proximal aortic pressure and flow waves and play a role in systolic hypertension. A measure of wave reflection, receiving much attention, is the augmentation index (AI), the ratio of the secondary rise in pressure and pulse pressure. AI can be limiting, because it depends not only on the magnitude of wave reflection but also on wave shapes and timing of incident and reflected waves. More accurate measures are obtainable after separation of pressure in its forward (P(f)) and reflected (P(b)) components. However, this calculation requires measurement of aortic flow. We explore the possibility of replacing the unknown flow by a triangular wave, with duration equal to ejection time, and peak flow at the inflection point of pressure (F(tIP)) and, for a second analysis, at 30% of ejection time (F(t30)). Wave form analysis gave forward and backward pressure waves. Reflection magnitude (RM) and reflection index (RI) were defined as RM=P(b)/P(f) and RI=P(b)/(P(f)+P(b)), respectively. Healthy subjects, including interventions such as exercise and Valsalva maneuvers, and patients with ischemic heart disease and failure were analyzed. RMs and RIs using F(tIP) and F(t30) were compared with those using measured flow (F(m)). Pressure and flow were recorded with high fidelity pressure and velocity sensors. Relations are: RM(tIP)=0.82RM(mf)+0.06 (R(2)=0.79; n=24), RM(t30)=0.79RM(mf)+0.08 (R(2)=0.85; n=29) and RI(tIP)=0.89RI(mf)+0.02 (R(2)=0.81; n=24), RI(t30)=0.83RI(mf)+0.05 (R(2)=0.88; n=29). We suggest that wave reflection can be derived from uncalibrated aortic pressure alone, even when no clear inflection point is distinguishable and AI cannot be obtained. Epidemiological studies should establish its clinical value.