Mitral Regurgitation

Transcatheter mitral valve repair in a liver transplant candidate

Untreated severe mitral regurgitation (MR) is associated with poor outcomes due to the adverse consequences of long-standing volume overload on the left ventricle and left atrium, which leads to pulmonary hypertension and right-sided heart failure. Early intervention results in favorable long-term outcomes making appropriate timing of intervention very critical. We present a 53-year-old male with severe symptomatic MR and right sided-heart failure which progressed to cardiac cirrhosis necessitating enrollment to the liver transplant list. Transcatheter mitral valve repair (TMVR) using MitraClip implantation resulted in impressive clinical improvement and resolution of cirrhosis. Eventually, the patient was taken off the transplant list. Treatment of severe MR may lead to improvements in congestive hepatopathy.

Twelve-month healthcare utilization and expenditures in Medicare fee-for-service patients with clinically significant mitral regurgitation

Aim: This study sought to quantify the healthcare burden of Medicare patients with clinically significant mitral regurgitation (sMR). Materials & methods: Proxy definitions were used for sMR, including MR surgery, atrial fibrillation, pulmonary hypertension or >2 echocardiograms. Results: In this study, 11,173 patients had significant degenerative MR (sDMR); 25,402 had significant functional MR (sFMR); and 12,232 had significant uncharacterized MR (sUMR). Patients with sFMR (18,880) were more likely to be hospitalized and present to the emergency department compared with patients with sDMR (9,795) or sUMR (10,587). Annual healthcare expenditures for sMR patients were: US$29,328 for sFMR; US$17,112 for sUMR; and US$12,870 for sDMR. Conclusion: Novel therapeutic interventions merit further evaluation to reduce the substantial healthcare burden of sMR in the Medicare population.

[Transesophageal echocardiography in emergency and intensive care medicine : Indication and implementation]

Transesophageal echocardiography (TEE) in emergency and intensive care medicine represents an additional semi-invasive method to confirm or rebut suspected diagnoses in critically ill patients. Three-dimensional (3D)-TEE investigations are established in the clinical workflow of emergency and intensive care units because 3D-TEE investigations permit a differentiation of artifacts due to oblique views by simultaneous documentation of sectional planes and en face views of characteristic cardiac structures. Thus, the level of diagnostic validity can be significantly increased by 3D-TEE investigation. The main indications of TEE investigation in emergency medicine are hemodynamic instability due to myocardial, pericardial or valvular heart diseases as well as suspected endocarditis and aortic dissection.

An ex vivo model of left ventricular dilation and functional mitral regurgitation to facilitate the development of surgical techniques

OBJECTIVE

Functional mitral regurgitation (FMR) is a common sequelae of myocardial ischemic disease. It results from annular dilation and outward rotation of the posterior papillary muscle. Different surgical techniques are under investigation for the treatment of FMR. However, an ex vivo model of FMR would be valuable to develop and compare the effect of techniques on the geometry of the left ventricle and the correction of FMR.

METHODS

FMR was induced in explanted ovine hearts (n = 12) by manual dilation of the mitral annulus or by posterior papillary muscle repositioning with a patch. Left ventricular dimensions were measured. Mitral regurgitant volume (MRV) was measured in a continuous flow system.

RESULTS

Annular dilation significantly increased MRV from 93.0 ± 110.4 to 472.2 ± 211.8 mL/min (P = 0.031), and the patch increased it from 37.8 ± 55.2 to 365 ± 189.6 mL/min (P = 0.031), with no significant differences between the 2 groups. When both techniques were applied, MRV significantly increased to 1383.5 ± 567.0 mL/min (P = 0.0005). The left ventricular sphericity index decreased from 3.25 ± 0.7 to 2.34 ± 0.6 (P = 0.0025) after application of the patch. The posterior papillary muscle was displaced after patch placement, following an outward rotation.

CONCLUSION

This ex vivo model reproduces annular dilation and outward rotation of the posterior papillary muscle, which are both present during FMR after ischemic myocardial disease. This model could be used to evaluate and compare interventions to treat FMR.

Left ventricular remodeling in preclinical experimental mitral regurgitation of dogs

Dogs with experimental mitral regurgitation (MR) provide insights into the left ventricular remodeling in preclinical MR. The early preclinical left ventricular (LV) changes after mitral regurgitation represent progressive dysfunctional remodeling, in that no compensatory response returns the functional stroke volume (SV) to normal even as total SV increases. The gradual disease progression leads to mitral annulus stretch and enlargement of the regurgitant orifice, further increasing the regurgitant volume. Remodeling with loss of collagen weave and extracellular matrix (ECM) is accompanied by stretching and hypertrophy of the cross-sectional area and length of the cardiomyocyte. Isolated ventricular cardiomyocytes demonstrate dysfunction based on decreased cell shortening and reduced intracellular calcium transients before chamber enlargement or decreases in contractility in the whole heart can be clinically appreciated. The genetic response to increased end-diastolic pressure is down-regulation of genes associated with support of the collagen and ECM and up-regulation of genes associated with matrix remodeling. Experiments have not demonstrated any beneficial effects on remodeling from treatments that decrease afterload via blocking the renin-angiotensin system (RAS). Beta-1 receptor blockade and chymase inhibition have altered the progression of the LV remodeling and have supported cardiomyocyte function. The geometry of the LV during the remodeling provides insight into the importance of regional differences in responses to wall stress.

Valvular heart disease: a primer for the clinical pharmacist

Valvular heart disease is a commonly encountered clinical condition that is not taught in most undergraduate and graduate pharmacy programs, leaving the practicing pharmacist without basic knowledge to expand on and subsequently apply to direct patient care. Unlike other areas of cardiology in which thousands of patients are recruited in many well-designed randomized clinical trials, data assessing treatments for valvular heart disease are limited and often consist of retrospective case series or observations. Our goal is to provide a basic overview of chronic valvular heart disease, with emphasis on describing the common conditions requiring surgery and the available options, as well as common pharmacologic therapies used in this patient population. Anomalies in valves can be broadly classified as stenosis and regurgitation. Depending on the valve and the type of anomaly, the impact on the cardiovascular system will vary. Understanding the hemodynamic consequences of aortic stenosis, aortic regurgitation, mitral stenosis, and mitral regurgitation is imperative to effectively counsel patients surrounding disease progression and self-monitoring, use of vasodilators, and prophylaxis for endocarditis and rheumatic fever. Further, patient characteristics factored into the choice of implanting either a bioprosthetic (tissue) or prosthetic (metal) valve encompass patient choice, life expectancy, and willingness or ability to accept lifelong anticoagulation therapy. The evolution of metal valves has resulted in newer generations under clinical study that have more laminar flow (minimizing interaction with blood products) and improved pyrolytic carbon (minimizing infection and interaction with blood products). Although antithrombotic therapy with warfarin is now mandatory in North America for all patients receiving metal valves, research is ongoing to assess the need with the most recent generation of valves.

Mitral valve regurgitation and 3D echocardiography

The mitral valve is a complex, dynamic and functional apparatus that can be altered by a wide range of disorders leading to stenosis or regurgitation. Surgical management of mitral valve disease may be difficult. Planned intervention may not always be feasible when the surgeon is faced with complex pathology that cannot be assessed fully by conventional 2D echocardiography. Transthoracic and transesophageal 3D echocardiography can provide a more reliable functional and anatomical assessment of the different valve components and evaluation of its geometry, which can aid the surgeon in planning a more suitable surgical intervention and improve outcomes. Although 3D echocardiography is a new technology, it has proven to be an important modality for the accurate assessment of valvular heart disease and in the future, it promises to be an essential part in the routine assessment of cardiovascular patients.

Conformational constraints on side chains in protein residues increase their information content

Like all other complex biological systems, proteins exhibit properties not seen in free amino acids (i.e., emergent properties). The present investigation arose from the deduction that proteins should offer a good model to approach the reverse phenomenon, namely top-down constraints experienced by protein residues compared to free amino acids. The crystalline structure of profilin Ib, a contractile protein of Acanthamoeba castellanii, was chosen as the object of study and submitted to 2-ns molecular dynamics simulation. The results revealed strong conformational constraints on the side chain of residues compared to the respective free amino acids. A Shannon entropy (SE) analysis of the conformational behavior of the side chains showed in most cases a strong decrease in the SE of the chi1 and chi2 dihedral angles compared to free amino acids. This is equivalent to stating that conformational constraints on the side chain of residues increase their information content and hence recognition specificity compared to free amino acids. In other words, the vastly increased information content of a protein relative to its free monomers is embedded not only in the tertiary structure of the backbone, but also in the conformational behavior of the side chains. The postulated implication is that both backbone and side chains, by virtue of being conformationally constrained, contribute to the recognition specificity of the protein toward other macromolecules and ligands.