Differential effects of the angiotensin-converting enzyme inhibitor lisinopril versus the beta-adrenergic receptor blocker atenolol on hemodynamics and left ventricular contractile function in experimental mitral regurgitation

Contributions of mechanical loading and hormonal changes to eccentric hypertrophy during volume overload: a Bayesian analysis using logic-based network models

Primary mitral regurgitation (MR) is a pathology that alters mechanical loading on the left ventricle, triggers an array of compensatory neurohormonal responses, and induces a distinctive ventricular remodeling response known as eccentric hypertrophy. Drug therapies may alleviate symptoms, but only mitral valve repair or replacement can provide significant recovery of cardiac function and dimensions. Questions remain about the optimal timing of surgery, with 20% of patients developing systolic dysfunction post-operatively despite being treated according to the current guidelines. Thus, better understanding of the hypertrophic process in the setting of ventricular volume overload (VO) is needed to improve and better personalize the management of MR. To address this knowledge gap, we employ a Bayesian approach to combine data from 70 studies on experimental volume overload in dogs and rats and use it to calibrate a logic-based network model of hypertrophic signaling in myocytes. The calibrated model predicts that growth in experimental VO is mostly driven by the neurohormonal response, with an initial increase in myocardial tissue stretch being compensated by subsequent remodeling fairly early in the time course of VO. This observation contrasts with a common perception that volume-overload hypertrophy is driven primarily by increased myocyte strain. The model reproduces many aspects of 43 studies not used in its calibration, including infusion of individual hypertrophic agonists alone or in combination with various drugs commonly employed to treat heart failure, as well as administration of some of those drugs in the setting of experimental volume overload. We believe this represents a promising approach to using the known structure of an intracellular signaling network to integrate information from multiple studies into quantitative predictions of the range of expected responses to potential interventions in the complex setting of cardiac hypertrophy driven by a combination of hormonal and mechanical factors.

Management of Chronic Congestive Heart Failure Caused by Myxomatous Mitral Valve Disease in Dogs: A Narrative Review from 1970 to 2020

Simple Summary

Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in dogs. The progression of the disease and the increasing severity of valvular regurgitation cause a volume overload of the left heart, leading to left atrial and ventricular remodeling and congestive heart failure (CHF). The treatment of chronic CHF secondary to MMVD in dogs has not always been the same over time. In the last fifty years, the drugs utilized have considerably changed, as well as the therapeutic protocols. Some drugs have also changed their intended use. An analysis of the literature concerning the therapy of chronic heart failure in dogs affected by this widespread degenerative disease is not available; a synthesis of the published literature on this topic and a description of its current state of art are needed. To the authors’ knowledge, a review of this topic has never been published in veterinary medicine; therefore, the aim of this study is to overview the treatments of chronic CHF secondary to MMVD in dogs from 1970 to 2020 using the general framework of narrative reviews.

Abstract

The treatment of chronic congestive heart failure (CHF), secondary to myxomatous mitral valve disease (MMVD) in dogs, has considerably changed in the last fifty years. An analysis of the literature concerning the therapy of chronic CHF in dogs affected by MMVD is not available, and it is needed. Narrative reviews (NRs) are aimed at identifying and summarizing what has been previously published, avoiding duplications, and seeking new study areas that have not yet been addressed. The most accessible open-access databases, PubMed, Embase, and Google Scholar, were chosen, and the searching time frame was set in five decades, from 1970 to 2020. The 384 selected studies were classified into categories depending on the aim of the study, the population target, the pathogenesis of MMVD (natural/induced), and the resulting CHF. Over the years, the types of studies have increased considerably in veterinary medicine. In particular, there have been 43 (24.29%) clinical trials, 41 (23.16%) randomized controlled trials, 10 (5.65%) cross-over trials, 40 (22.60%) reviews, 5 (2.82%) comparative studies, 17 (9.60%) case-control studies, 2 (1.13%) cohort studies, 2 (1.13%) experimental studies, 2 (1.13%) questionnaires, 6 (3.40%) case-reports, 7 (3.95%) retrospective studies, and 2 (1.13%) guidelines. The experimental studies on dogs with an induced form of the disease were less numerous (49–27.68%) than the studies on dogs affected by spontaneous MMVD (128–72.32%). The therapy of chronic CHF in dogs has considerably changed in the last fifty years: in the last century, some of the currently prescribed drugs did not exist yet, while others had different indications.

A new perspective on cardiovascular drift during prolonged exercise

Prolonged exercise induces cardiovascular drift, which is characterized by decreasing mean arterial pressure (MAP), stroke volume and heart rate increase. Cardiovascular drift has been debated for a long time. Although the exact mechanisms underlying cardiovascular drift are still unknown, two theories have been proposed. The first is that increased skin blood flow displaces blood volume from central circulation to the periphery, which reduces stroke volume. According to this theory, the rise in heart rate is presumably responding to the drop in stroke volume and MAP. The alternative theory is that an increase in heart rate is due to an increase in sympathetic nervous activity causing reducing time at diastole, and therefore stroke volume. It may be difficult to determine a single robust factor accounting for cardiovascular drift, due to the broad range of circumstances. The primary focus of this review is to elucidate our understanding of cardiovascular drift during prolonged exercise through nitric oxide and force-frequency relationship. We highlight for the very first time that cardiovascular drift (in some conditions and within a specific time period) may be considered as a protective strategy against potential damage that could be induced by the intense and prolonged contraction of the myocardium.

2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the valvular heart disease guideline provides recommendations for clinicians to diagnose and manage valvular heart disease as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to March 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, Cochrane, Agency for Healthcare Research and Quality Reports, and other selected database relevant to this guideline. Structure: Many recommendations from the earlier valvular heart disease guidelines have been updated with new evidence and provides newer options for diagnosis and treatment of valvular heart disease. This summary includes only the recommendations from the full guideline which focus on diagnostic work-up, the timing and choice of surgical and catheter interventions, and recommendations for medical therapy. The reader is referred to the full guideline for graphical flow charts, text, and tables with additional details about the rationale for and implementation of each recommendation, and the evidence tables detailing the data considered in developing these guidelines.

Dynamic Changes in the Molecular Signature of Adverse Left Ventricular Remodeling in Patients With Compensated and Decompensated Chronic Primary Mitral Regurgitation

BACKGROUND

There is no proven medical therapy that attenuates adverse left ventricular remodeling in patients with chronic primary mitral regurgitation (CPMR). Identification of molecular pathways important in the progression of left ventricular remodeling in patients with CPMR may lead to development of new therapeutic strategies.

METHODS AND RESULTS

We performed baseline echocardiographic, cardiac catheterization, and serum NT-pro-BNP analysis in patients with severe CPMR awaiting mitral valve surgery and stratified the study population into compensated or decompensated CPMR. We obtained left ventricular endomyocardial biopsies (n=12) for mRNA expression analysis, and compared baseline transcript levels of 109 genes important in volume-overload left ventricular remodeling with levels in normal hearts (n=5) and between patients with compensated (n=6) versus decompensated (n=6) CPMR. Patients were then randomized to treatment with and without carvedilol and followed until the time of surgery (mean follow-up 8.3 months) when repeat endomyocardial biopsies were obtained to correlate transcriptional dynamics with indices of adverse remodeling. CPMR was associated with increased NPPA expression levels (21.6-fold, P=0.004), decreased transcripts of genes important in cell survival, and enrichment of extracellular matrix genes. Decompensated CPMR was associated with downregulation of SERCA2 (0.77-fold, P=0.009) and mitochondrial gene expression levels and upregulation of genes related to inflammation, the extracellular matrix, and apoptosis, which were refractory to carvedilol therapy.

CONCLUSIONS

Transition to decompensated CPMR is associated with calcium dysregulation, increased expression of inflammatory, extracellular matrix and apoptotic genes, and downregulation of genes important in bioenergetics. These changes are not attenuated by carvedilol therapy and highlight the need for development of specific combinatorial therapies, targeting myocardial inflammation and apoptosis, together with urgent surgical or percutaneous valve interventions.

Left ventricular remodelling in chronic primary mitral regurgitation: implications for medical therapy

Surgical repair or replacement of the mitral valve is currently the only recommended therapy for severe primary mitral regurgitation. The chronic elevation of wall stress caused by the resulting volume overload leads to structural remodelling of the muscular, vascular and extracellular matrix components of the myocardium. These changes are initially compensatory but in the long term have detrimental effects, which ultimately result in heart failure. Understanding the changes that occur in the myocardium due to volume overload at the molecular and cellular level may lead to medical interventions, which potentially could delay or prevent the adverse left ventricular remodelling associated with primary mitral regurgitation. The pathophysiological changes involved in left ventricular remodelling in response to chronic primary mitral regurgitation and the evidence for potential medical therapy, in particular beta-adrenergic blockers, are the focus of this review.

The characteristics of a porcine mitral regurgitation model

The porcine mitral regurgitation (MR) model is a common cardiovascular animal model. Standardized manufacturing processes can improve the uniformity and success rate of the model, and systematic research can evaluate its potential use. In this study, 17 pigs were divided into an experimental group (n=11) and a control group (n=6). We used a homemade retractor to cut the mitral chordae via the left atrial appendage to establish a model of MR; the control group underwent a sham surgery. The model animals were followed for 30 months after the surgery. Enlargement and fibrosis of the left atrium were significant in the experimental group compared with those in the control group, and left atrial systolic function decreased significantly. In addition, model animals showed preserved left ventricular systolic function. There were no differences in left atrial potential or left ventricular myocardial fibrosis between the two groups. Atrial fibrillation susceptibility in the experimental group was higher than that in the control group. Our method enables the simple and effective production of a MR model with severe reflux that can be used for pathophysiological studies of MR, as well as for the development of preclinical surgical instruments and their evaluation. This model could also be used to study atrial fibrillation and myocardial fibrosis but is not suitable for studies of heart failure.

Impact of Beta-Blockade on Cardiac Events in Patients with Chronic Severe Nonischemic Mitral Regurgitation

OBJECTIVES

The aim of this study was to examine the impact of beta-blockade on cardiac events among patients with initially asymptomatic chronic severe nonischemic mitral valve regurgitation (MR).

METHODS

Data from 52 consecutive patients in our prospective natural history study of isolated chronic severe nonischemic MR were assessed post hoc over 19 years to examine the relation of chronic beta-blockade use to subsequent cardiac events (death or indications for mitral valve surgery, MVS). At entry, all patients were free of surgical indications; 9 received beta-blockers. Cardiac event rate differences were analyzed by Kaplan-Meier log rank comparison.

RESULTS

During follow-up, cardiac events included sudden death (1), heart failure (8), atrial fibrillation (6), left ventricular dimensions at systole ≥4.5 cm (11), left ventricular ejection fraction <60% (6), right ventricular ejection fraction <35% (2), and a combination of cardiac events (7). The cardiac event risk was 4-fold higher among patients receiving beta-blockers (average annual risk = 60.6%) versus those not receiving beta-blockers (average annual risk = 15.2%; p = 0.001). These effects remained statistically significant (p = 0.005) when analysis was adjusted for other baseline covariates.

CONCLUSIONS

Beta-blockade appears to confer an increased risk of sudden cardiac death or indications for MVS among patients with chronic severe nonischemic MR. Randomized trials are needed to confirm these findings.

Targeting the sympatho-adrenergic link in chronic rheumatic mitral regurgitation: assessing the role of oral beta-blockers

INTRODUCTION

Chronic mitral regurgitation (MR) is characterized by adverse ventricular remodeling and progressive LV dysfunction leading to heart failure (HF). Beta-blockers (BB) improve LV remodeling and prognosis in patients with HF. As chronic severe MR results in neuroendocrine activation similar to HF, it is likely that BB may also exert favorable effects in these patients. No study has assessed the role of oral BB therapy in chronic rheumatic MR.

AIMS

A total of 100 patients of chronic rheumatic MR (mean age 30±13.48 years, NYHA 2.2±0.5) were randomized to BB (Metoprolol, 37±13.5 mg, n=48) vs no BB (n=52) in addition to standard therapy.

RESULTS

Baseline BNP and echocardiographic parameters were comparable in the two groups. At 3 months, BB therapy resulted in significantly lower NYHA class (1.97 vs 2.35), BNP (141 vs 207 pg/mL), LV end-systolic (35.89 vs 51.30) and LV end-diastolic volumes (101 vs 128 mL/m(2) ), LV end-systolic stress (81.1 vs 93.3 dyn/cm(2) ), LV mass (122 vs 154 gm/m(2) ), and LV work (737.02 vs 952.82 mm Hg L/min, all P significant). Therapy with BB resulted in a -15.6%, -10.4%,-12.1%, and -7.3% reduction in LV end-systolic and end-diastolic dimensions and LVESVi and LVEDVi, respectively. Following BB therapy, BNP levels, end-systolic stress, indexed LV mass, and LV work also reduced significantly by 27.3%, 15.6%, 8.7%, and 28%, respectively. The control group had no significant change. The MR grade reduced from severe to moderate in 11% of those on BB (controls: no change). At 6 months, the BB group had further improvement in all echocardiographic parameters ranging from +9.1 to -18.2%.

CONCLUSION

In this first study of BB in rheumatic MR, targeting the sympatho-adrenergic axis exerted favorable effects on NYHA class, LV volumes, LV end-systolic stress, and LV work. Further studies are required to elucidate the role of BB in rheumatic MR.

Afterload Reduction May Halt and Beta-Adrenergic Blockade May Worsen Progression of Left Ventricular Dysfunction in Patients With Chronic Compensated Mitral Regurgitation: A Retrospective Cohort Study

Severe chronic mitral regurgitation (MR) is associated with progressive left ventricular (LV) systolic dysfunction. Both afterload reduction and beta-adrenergic blockade have been suggested as methods for preventing LV dysfunction in asymptomatic patients with MR and normal LV function, who are therefore not yet candidates for surgical intervention. The objective of this study was to determine if afterload reduction reduces progression of LV dysfunction in patients with severe MR. The reports of echocardiographic studies performed 20 ±14 months apart were compared in a retrospective cohort of 134 asymptomatic patients with moderate-severe chronic MR and baseline ejection fraction (LVEF) >50%. Groups were defined by exposure to any afterload-reducing drug: Group 0, no exposure; Group 1, exposure beginning after the first echocardiogram; and Group 2, drug exposure beginning before the baseline echocardiogram. The groups differed importantly only in treatment duration. In 72 patients not exposed to beta-adrenergic blockade, LVEF decreased by a relative —3.2% in Group 0, while Group 1 increased by 3.4% and Group 2 increased by 5.1%, p <0.01. Among 62 patients exposed to beta-adrenergic blockade, LVEF consistently worsened (Group 0, 4.8%; Group 1, —3.3%; Group 2, —1.7%; p = 0.71) compared to the 72 patients without beta-adrenergic blockade. In a multivariate model that included treatment duration and exposure to other medications, the beneficial effect of afterload reduction (p <0.03) and the deleterious effect of beta-adrenergic blockade (p < 0.02) were significant. Afterload reduction halted or reversed the progressive worsening of left ventricular function while beta-adrenergic blockade had a deleterious effect.

Effect of Angiotensin-converting Enzyme Inhibitors on Phenylephrine Responsiveness in Patients with Valvular Heart Disease

We studied patients with valvular heart disease to investigate whether chronic pre-operative treatment with angiotensin-converting enzyme (ACE) inhibitors modulates the effect of phenylephrine (PE) on anaesthesia-induced hypotension. Sixty-five patients were enrolled in the study and hypotension developed after anaesthesia in 36 (18 in the control group and 18 in the ACE inhibitor group). These patients received PE infusions, which were increased in a stepwise fashion at 10-min intervals. Increased mean arterial pressure due to PE infusion was significant only in the control group. There was no significant difference in pressor response or change in haemodynamic variables with PE infusion between the two groups. Treatment with ACE inhibitors did not increase the incidence of hypotensive episodes or significantly modify pressor response after anaesthesia in patients with valvular heart disease.

Renin-angiotensin system inhibitors in patients with myocardial infarction and secondary mitral regurgitation

OBJECTIVES

Secondary mitral regurgitation (MR) is negatively related to the prognosis of patients with myocardial infarction (MI). Renin-angiotensin system inhibitors (RASI) may favourably affect left ventricular remodelling and reduce afterload and thereby improve prognosis of secondary MR. The aim of this study was to investigate if use of RASI improves prognosis of patients with MI with secondary MR.

METHODS

A total of 953 patients with MI were enrolled in this study. Long-term prognosis was compared between patients with MI with no/mild MR (n=657), moderate MR (n=196) and severe MR (n=100). Patients with MI with significant (≥moderate) secondary MR were further divided into those treated with and without RASI. Survival and cardiac-event (all-cause death and congestive heart failure)-free survival were compared.

RESULTS

Long-term survival was significantly associated with severity of MR (log-rank, p<0.0001). In patients with significant MR (n=296), RASI was used in 130 patients (44%) and not used in 166 patients (56%). Ejection fraction (47.3±12.2 vs 46.6±13.4%, p=NS) and E/e' (18.4±8.1 vs 16.5±7.0, p=NS) were similar between the two groups. Kaplan-Meier curves for cardiac-event-free survival demonstrated that use of RASI was associated with better survival (p=0.006) as well as event-free survival (p=0.02). By univariable and multivariable Cox proportional hazard analysis, age (HR 1.046, 95% CI 1.002 to 1.091, p=0.039) and RASI (HR 0.480, 95% CI 0.231 to 0.995), p=0.048) were independent predictors of cardiac events.

CONCLUSIONS

Secondary MR affects prognosis in patients with MI. Use of RASI may be associated with better long-term prognosis in patients with MI with significant MR.

Drug Therapy for Heart Valve Diseases

Valvular heart diseases (VHDs) are progressive. When not caused by acute comorbidities they are generally characterized by long asymptomatic phases during which hemodynamic severity may progress leading to morbidity and mortality. Treatment depends on VHD type and severity but when severe and symptomatic, usually involves mechanical intervention. Asymptomatic patients, and those who lack objective descriptors associated with high risk, are closely observed clinically with optimization of associated cardiovascular risk factors until surgical indications develop. Though often prescribed based on theory, no rigorous evidence supports pharmacological therapy in most chronic situations though drugs may be appropriate in acute valvular diseases, or as a bridge to surgery in severely decompensated patients. Herein, we examine evidence supporting drug use for chronic VHDs.

Short-term follow-up of exercise training program and beta-blocker treatment on quality of life in dogs with naturally acquired chronic mitral valve disease

This study aimed to evaluate the effects of carvedilol treatment and a regimen of supervised aerobic exercise training on quality of life and other clinical, echocardiographic, and biochemical variables in a group of client-owned dogs with chronic mitral valve disease (CMVD). Ten healthy dogs (control) and 36 CMVD dogs were studied, with the latter group divided into 3 subgroups. In addition to conventional treatment (benazepril, 0.3-0.5 mg/kg once a day, and digoxin, 0.0055 mg/kg twice daily), 13 dogs received exercise training (subgroup I; 10.3 ± 2.1 years), 10 dogs received carvedilol (0.3 mg/kg twice daily) and exercise training (subgroup II; 10.8 ± 1.7 years), and 13 dogs received only carvedilol (subgroup III; 10.9 ± 2.1 years). All drugs were administered orally. Clinical, laboratory, and Doppler echocardiographic variables were evaluated at baseline and after 3 and 6 months. Exercise training was conducted from months 3-6. The mean speed rate during training increased for both subgroups I and II (ANOVA, P>0.001), indicating improvement in physical conditioning at the end of the exercise period. Quality of life and functional class was improved for all subgroups at the end of the study. The N-terminal pro-brain natriuretic peptide (NT-proBNP) level increased in subgroup I from baseline to 3 months, but remained stable after training introduction (from 3 to 6 months). For subgroups II and III, NT-proBNP levels remained stable during the entire study. No difference was observed for the other variables between the three evaluation periods. The combination of carvedilol or exercise training with conventional treatment in CMVD dogs led to improvements in quality of life and functional class. Therefore, light walking in CMVD dogs must be encouraged.

Chronic vagus nerve stimulation improves left ventricular function in a canine model of chronic mitral regurgitation

BACKGROUND

Autonomic dysfunction, characterized by sympathetic activation and vagal withdrawal, contributes to the progression of heart failure (HF). We hypothesized that chronic vagus nerve stimulation (VNS) could prevent left ventricular (LV) remodeling and dysfunction in a canine HF model induced by chronic mitral regurgitation (MR).

METHODS AND RESULTS

After the MR inducing procedure, 12 survived canines were randomly divided into the control (n = 6) and the VNS (n = 6) groups. At month 2, a VNS stimulator system was implanted in all canines. From month 3 to month 6, VNS therapy was applied in the VNS group but not in the control group. At month 6, compared with the control group, the canines in VNS group had significantly higher cardiac output (2.3 ± 0.3 versus 2.9 ± 0.4 L/min, P < 0.05, LV forward stroke volume (20.1 ± 3.7 versus 24.8 ± 3.9 ml, P < 0.05), and end-systolic stiffness constant (2.2 ± 0.3 versus 2.7 ± 0.3, P < 0.05). NT-proBNP and C-reactive protein were decreased significantly in the VNS group. However, no statistical difference was found in LV ejection fraction, LV end-diastolic dimension, LV end-diastolic volume, myocyte cross-sectional area, or collagen volume fraction between two groups.

CONCLUSIONS

Chronic VNS therapy may ameliorate MR-induced LV contractile dysfunction and improve the expression of biomarkers, but has less effect in improving LV chamber remodeling.

Mitral valve repair in asymptomatic patients with severe mitral regurgitation: pushing past the tipping point

Degenerative mitral valve regurgitation (MR) is the one of the most frequent valvular heart conditions in the Western world and is increasingly recognized as an important preventable cause of chronic heart failure. This condition also represents the most common indication for mitral surgery and is of particular interest because the mitral valve can be repaired in most patients with very low surgical risk. Historical single-center studies have supported the performance of "early mitral valve repair" in asymptomatic patients with severe degenerative MR to normalize survival and improve late outcomes. Emerging recent evidence further indicates for the first time that the prompt surgical correction of severe MR due to flail mitral leaflets within 3 months following diagnosis in asymptomatic patients without classical Class I indications (symptoms or left ventricular dysfunction) conveys a 40% decrease in the risk of late death and a 60% diminution in heart failure incidence. A 10-point rationale based on the weight of rapidly accumulating clinical data, supports the performance of early mitral valve repair even in the absence of symptoms, left ventricular dysfunction, or guideline-based triggers; when effective operations can be provided using conventional or minimally invasive techniques at very low surgical risk.

Effects of early, late, and long-term nonselective β-blockade on left ventricular remodeling, function, and survival in chronic organic mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) produces sympathetic nervous system activation which is detrimental in other causes of heart failure. However, whether β-blockade is beneficial in MR has not been determined.

METHODS AND RESULTS

Eighty-seven rats with significant organic MR were randomized to the β-blockade group (n=43) or the control group (n=44). Carvedilol was started in week 2 post MR induction and given for 23 to 35 weeks in the β-blockade group. Echocardiography was performed at baseline and at weeks 2, 6, 12, 24, 30, and 36 after MR induction. After 23 weeks of β-blockade, heart rates were significantly reduced by carvedilol (308 ± 25 versus 351 ± 31 beats per minute; P<0.001). Left ventricular end-diastolic (2.2 ± 0.7 versus 1.59 ± 0.6 mL; P<0.001), end-systolic volumes (0.72 ± 0.42 versus 0.40 ± 0.19 mL; P<0.001), and mass index (2.40 ± 0.55 versus 2.06 ± 0.62 g/kg; P<0.001) were significantly higher, and left ventricular fraction shortening (33 ± 7% versus 38 ± 7%; P<0.001) and ejection fraction (69 ± 11% versus 75 ± 7%; P<0.001) were significantly lower in the β-blockade group than in the control group. Systolic blood pressure was lower in the β-blockade group than in the control group (114 ± 10 versus 93 ± 12 mm Hg; P<0.005). Survival probability was significantly lower in the early β-blockade group than in the control group (88% versus 96%; P=0.03).

CONCLUSIONS

Early and long-term nonselective β-blockade was associated with adverse left ventricular remodeling, systolic dysfunction, and a reduction in survival in the experimental rat model of organic MR.

Atrial natriuretic peptide as a marker of heart failure in children with left ventricular volume overload

AIM

To evaluate the role of atrial natriuretic peptide (ANP) in differentiating the aetiology of heart failure in children with left ventricular (LV) volume overload.

METHODS

The study was conducted on 48 patients with LV volume overload (G one: rheumatic heart disease in failure; G2: compensated rheumatic heart disease; G3: congenital left to right shunt; and G4: dilated cardiomyopathy). Twelve healthy children served as a control group. New York Heart Association (NYHA) class, LV dimensions and functions using Vivid 7 dimensions were evaluated. Serum ANP was measured using the ELISA technique, before and 3 months after treatment with angiotensin converting enzyme inhibitor.

RESULTS

ANP was raised in all patients as compared to controls (G one: 28.33 ± 5.78, G2: 26.5 ± 4.11, G3: 28.5 ± 6.6, G4: 29.25 ± 4.5 pg/mL, control group: 5.54 ± 1.4 pg/mL, P < 0.001 for all) and varied significantly between different NYHA classes regardless of the underlying cardiac lesion. It was significantly higher in group 1 than 2 (P < 0.05). It decreased significantly after treatment (G1: 15.3 ± 5.3, G2: 10.7 ± 2.5, G3: 11.5 ± 3.8, G4: 15.7 ± 10.7 pg/mL, P < 0.001). The rate of change of ANP correlated with that of LV end diastolic diameter (r = 0.3, P < 0.05) irrespective of the underlying cause.

CONCLUSION

ANP increases in cases of LV volume overload irrespective of the aetiology of heart failure. It can differentiate between children in quiescent state from those in clinical failure even in the absence of echocardiographically detectable systolic dysfunction. Furthermore, it can monitor LV remodelling with treatment.

Pharmacologic management of myxomatous mitral valve disease in dogs

Myxomatous mitral valve disease (MMVD) causing mitral regurgitation is the most important disease of the heart in small animal cardiovascular medicine. Because MMVD is an example of a chronic disease that progresses from mild to severe over years, treatment strategies change with the stage of the disease. In this review the treatment options are compared and contrasted as they are discussed relative to the recently published ACVIM consensus statement regarding the treatment of MMVD. Results from clinical trials and evidence-based medicine are likely to provide significant improvements in the management of MMVD in the coming decades.

Structural remodeling and mechanical function in heart failure

The cardiac extracellular matrix (ECM) is the three-dimensional scaffold that defines the geometry and muscular architecture of the cardiac chambers and transmits forces produced during the cardiac cycle throughout the heart wall. The cardiac ECM is an active system that responds to the stresses to which it is exposed and in the normal heart is adapted to facilitate efficient mechanical function. There are marked differences in the short- and medium-term changes in ventricular geometry and cardiac ECM that occur as a result of volume overload, hypertension, and ischemic cardiomyopathy. Despite this, there is a widespread view that a common remodeling "phenotype" governs the final progression to end-stage heart failure in different forms of heart disease. In this review article, we make the case that this interpretation is not consistent with the clinical and experimental data on the topic. We argue that there is a need for new theoretical and experimental models that will enable stresses acting on the ECM and resultant deformations to be estimated more accurately and provide better spatial resolution of local signaling mechanisms that are activated as a result. These developments are necessary to link the effects of structural remodeling with altered cardiac mechanical function.

Changes in mitral annular geometry and dynamics with ß-blockade in patients with degenerative mitral valve disease

BACKGROUND

remodeling of the mitral annulus contributes to progression of mitral regurgitation (MR). In patients with moderate-to-severe MR, short-term treatment with β-blockers has been shown to increase left ventricular (LV) end-diastolic and end-systolic volume, and this could deleteriously increase mitral valve annular dimensions. The objective of this study was to quantify the effects of a short duration of β-blocker treatment on mitral annular dimensions and dynamics in patients with MR due to primary degenerative valve disease.

METHODS AND RESULTS

twenty-five patients with moderate-to-severe degenerative MR and normal LV systolic function were studied in a double-blind crossover experiment using a β1-selective adrenergic blocker and placebo administered for 14±3 days. Cardiac MRI images were acquired after each treatment period to quantify mitral annular dimensions. At end diastole, there was no change in annular area (1659±331 versus 1632±299 mm(2); P<0.19), annular perimeter (154.3±16.4 versus 152±13.9 mm; P<0.13), septal-lateral (SL) dimension (38.0±5 versus 39.0±4.5 mm; P<0.15), or annular height (9.8±3.8 versus 9.5±2.5 mm; P<0.53). β-blockade resulted in significant end-diastole decreases in commissure-commissure dimension (48.9±4.6 versus 47.2±4.0 mm; P<0.01) and eccentricity (1.3±0.2 versus 1.2±0.1; P<0.01). At end systole (ES), β-blockade conferred a small, but significant decrease in annular perimeter (161.0±19.3 versus 156.8±16.9 mm; P<0.04) and eccentricity (1.2±0.1 versus 1.1±0.1; P<0.02), and the SL dimension significantly increased (41.5±5.7 versus 43.0±5.3 mm; P<0.03). Commissure-commissure dimension, annular area, and annular height at ES were not significantly different.

CONCLUSIONS

despite significant increases in LV end-diastolic and end-systolic volume, short-term β-blocker treatment of patients with moderate-to-severe MR reduced or preserved all mitral annular dimensions except SL at ES.

Microarray identifies extensive downregulation of noncollagen extracellular matrix and profibrotic growth factor genes in chronic isolated mitral regurgitation in the dog

BACKGROUND

The volume overload of isolated mitral regurgitation (MR) in the dog results in left ventricular (LV) dilatation and interstitial collagen loss. To better understand the mechanism of collagen loss, we performed a gene array and overlaid regulated genes into ingenuity pathway analysis.

METHODS AND RESULTS

Gene arrays from LV tissue were compared in 4 dogs before and 4 months after MR. Cine-magnetic resonance-derived LV end-diastolic volume increased 2-fold (P=0.005), and LV ejection fraction increased from 41% to 53% (P<0.007). LV interstitial collagen decreased 40% (P<0.05) compared with controls, and replacement collagen was in short strands and in disarray. Ingenuity pathway analysis identified Marfan syndrome, aneurysm formation, LV dilatation, and myocardial infarction, all of which have extracellular matrix protein defects and/or degradation. Matrix metalloproteinase-1 and -9 mRNA increased 5- (P=0.01) and 10-fold (P=0.003), whereas collagen I did not change and collagen III mRNA increased 1.5-fold (P=0.02). However, noncollagen genes important in extracellular matrix structure were significantly downregulated, including decorin, fibulin 1, and fibrillin 1. In addition, connective tissue growth factor and plasminogen activator inhibitor were downregulated, along with multiple genes in the transforming growth factor-beta signaling pathway, resulting in decreased LV transforming growth factor-beta1 activity (P=0.03).

CONCLUSIONS

LV collagen loss in isolated, compensated MR is chiefly due to posttranslational processing and degradation. The downregulation of multiple noncollagen genes important in global extracellular matrix structure, coupled with decreased expression of multiple profibrotic factors, explains the failure to replace interstitial collagen in the MR heart.

Effect of Beta-blocker therapy on survival in patients with severe mitral regurgitation and normal left ventricular ejection fraction

Chronic volume overload from chronic severe mitral regurgitation (MR) results in neuroendocrine activation similar to the heart failure syndrome despite normal left ventricular (LV) ejection fraction (EF). Hence, the hypothesis that beta-blocker (BB) therapy may have a beneficial effect in these patients was tested using a large observational cohort. Our echocardiographic database was searched for patients with severe MR and normal LVEF. Full chart reviews were conducted for clinical and pharmacologic data. Survival was analyzed as a function of BB therapy. The search produced 895 patients aged 68 +/- 17 years, 44% men, with LVEF 66 +/- 7%. Of these, 32% were on BB therapy. Use of a BB was associated with a significantly decreased mortality hazard of 0.62 (95% confidence interval 0.46 to 0.83, p = 0.002), which was unchanged after adjusting for age, gender, LVEF, coronary artery disease, diabetes mellitus, hypertension, and cardiac valve surgery. The independent beneficial effect of BBs was seen in patients with or without coronary artery disease, those with or without hypertension, and patients managed both medically and surgically. In conclusion, use of BB therapy was associated with a significant independent survival benefit in patients with chronic severe MR with normal LVEF. This benefit was seen in patients with or without coronary artery disease, as well as patients managed both medically and surgically. Use of BBs in patients with severe MR despite normal LVEF is suggested.

Progressive nature of chronic mitral regurgitation and the role of tissue Doppler-derived indexes

The aim of this study was to determine whether severe mitral regurgitation (MR) is progressive and whether tissue-Doppler (TD)-derived indexes can detect early left ventricular (LV) dysfunction in chronic severe MR. Percutaneous rupture of mitral valve chordae was performed in pigs ( n = 8). Before MR (baseline), immediately after MR (post-MR), and at 1 and 3 mo after MR, cardiac function was assessed using conventional and TD-derived indexes. The severity of MR was quantified using regurgitant fraction and effective regurgitant orifice area (EROA). In all animals, MR was severe. On follow-up, the LV dilated progressively over time, but LV ejection fraction did not decrease. With the increase in LV dimensions, the forward stroke volume remained unchanged, but the mitral annular dimensions, EROA, and regurgitant fraction increased (EROA = 41 ± 2 and 51 ± 2 mm2 post-MR and at 3 mo, respectively, P < 0.01). Peak systolic myocardial velocities, strain, and strain rate increased acutely post-MR and remained elevated at 1 mo but declined by 3 mo (anterior strain rate = 2.9 ± 0.1 and 2.4 ± 0.2 s−1 post-MR and at 3 mo, respectively, P < 0.001). Therefore, in a chronic model of MR, serial echocardiography demonstrated that MR begets MR and that those TD-derived indexes that initially increased post-MR decreased to baseline before any changes in LV ejection fraction.

Short-term effects of cilazapril and atenolol on P-wave dispersion in patients with hypertension

INTRODUCTION

P-wave dispersion (PWD) has been shown to be a non-invasive electrocardiographic predictor for development of atrial fibrillation (AF). Thus, it may be possible to decrease AF risk through improvement in PWD. Our objective was to compare the effects of cilazapril and atenolol on P-wave duration and dispersion in patients with hypertension.

METHODS

A total of 38 newly diagnosed hypertensive patients were enrolled in the study. The patients were randomly assigned to receive treatment with either cilazapril (5 mg) or atenolol (50 mg). Doppler echocardiographic examination, P-wave durations and PWD were measured before and 1 mo after treatment

RESULTS

Both drugs reduced blood pressure significantly (P<0.001). Posttreatment heart rate was significantly lower in the atenolol group (P=0.01). The change in maximum P-wave duration was not significant. However, both agents decreased PWD (P=0.001 and P<0.001) and increased the minimum P-wave duration (P=0.004 and P=0.02).

CONCLUSION

Both cilazapril and atenolol treatments resulted in improvement in PWD.

[Ischemic mitral regurgitation: contributions of exercise echocardiography and new therapeutic perspectives]

The ischemic mitral regurgitation is defined by a left ventricular muscle disease affecting the function of normal mitral valve leaflets. This kind of mitral regurgitation is founded in about 20% of the ischemic cardiomyopathy and is attributed to the remodelling of the left ventricular shape. Its development is associated to a significantly worse prognosis. Frequently this ischemic mitral regurgitation will be associated to episode of acute heart failure decompensation. Its diagnosis is sometimes challenging as the degree of regurgitation might be extremely variable and affected by loading conditions. Echocardiography and especially exercise stress echocardiography has been demonstrated as an extremely powerful tool for its diagnosis and the prognostic evaluation. Its treatment should include the pharmacological treatment of the chonic heart failure and we are still waiting data in regard to the prognostic role of surgical mitral valvuloplastie. Works are still ongoing.

Role of vasodilators in regurgitant valve disease

Vasodilator therapy is designed to reduce regurgitant volume and improve left ventricular function. Acute administration reduces vascular resistance and decreases regurgitant volume and left ventricular filling pressure. These effects may be clinically useful in acute regurgitations, but less consistent results have been reported in long-term therapy. In chronic mitral functional regurgitation, vasodilator therapy has proved to have clinical or prognostic benefit only when heart failure or poor ventricular function is present. The indication of vasodilator treatment in aortic regurgitation has raised significant controversy. Several studies with small series have shown beneficial effects on regurgitant volume, ejection fraction, and mass of the left ventricle. Nevertheless, in the only two randomized long-term follow-up studies, results differed completely. In our experience, both nifedipine and enalapril failed to reduce the need for valvular surgery or show benefits in echocardiographic parameters. Vasodilator therapy would be indicated only in patients with severe aortic regurgitation and systemic hypertension, or when surgery is contraindicated.