Hypertrophic and restrictive cardiomyopathies in the elderly

Enhanced active cross-bridges during diastole: molecular pathogenesis of tropomyosin's HCM mutations

Three HCM-causing tropomyosin (Tm) mutants (V95A, D175N, and E180G) were examined using the thin-filament extraction and reconstitution technique. The effects of Ca(2+), ATP, phosphate, and ADP concentrations on cross-bridge kinetics in myocardium reconstituted with each of these mutants were studied at 25°C, and compared to wild-type (WT) Tm at physiological ionic strength (200 mM). All three mutants showed significantly higher (2-3.5 fold) low Ca(2+) tension (T(LC)) and stiffness than WT at pCa 8.0. High Ca(2+) tension (T(HC)) was significantly higher for E180G than that for WT, whereas T(HC) of V95A and D175N was similar to WT; high Ca(2+) stiffness (Y(HC)) had the same trend. The Ca(2+) sensitivity of isometric force was significantly greater for V95A and E180G than for WT, whereas that of D175N remained the same as for WT; for all mutants, cooperativity was lower than for WT. Nine kinetic constants and the cross-bridge distribution were deduced using sinusoidal analysis. The number of force-generating cross bridges was similar among the D175N, E180G, and WT Tm forms, but it was significantly larger in the case of V95A than WT. We conclude that the increased number of actively cycling cross bridges at pCa 8 is the major cause of Tm mutation-related HCM pathogenesis, which may result in diastolic dysfunction. Decreased contractility (T(act)) in V95A and D175N may further contribute to the severity of myocyte hypertrophy and related prognosis of the disease.

Magnetic resonance imaging in the evaluation of non-ischemic cardiomyopathies: current applications and future perspectives

Patients with non-ischemic cardiomyopathy often represent a diagnostic challenge, and correct etiologic diagnosis may influence outcomes. Lately, delayed myocardial enhancement MR imaging has been developed and is currently being used for a growing number of clinical applications. On delayed enhancement MR images, scarring or fibrosis appears as an area of high signal intensity, and the pattern by which this enhancement occurs in the myocardium allows distinction of many different pathologies. In nonischemic cardiomyopathy, the delayed enhancement usually does not occur in a coronary artery distribution and is often midwall rather than subendocardial or transmural. It could also guide myocardial biopsy to an affected area, increasing its yield. Cardiac magnetic resonance imaging has now a definitive role in clinical practice, and its capability to non-invasively provide high resolution images of the heart with good tissue characterization is redefining the understanding of the conditions that can adversely affect the myocardium.

Transcoronary ablation of septal hypertrophy for hypertrophic obstructive cardiomyopathy: feasibility, clinical benefit, and short term results in elderly patients

OBJECTIVE

To evaluate symptomatic and haemodynamic results of transcoronary ablation of septal hypertrophy for hypertrophic obstructive cardiomyopathy in elderly patients.

SETTING

Tertiary referral centre for patients with hypertrophic obstructive cardiomyopathy.

DESIGN

Retrospective study of two groups of consecutive patients divided at a median age (59 years).

PATIENTS

Transcoronary ablation of septal hypertrophy was compared for 80 patients (group 1) < 60 years of age and 77 patients (group 2) > or = 60 years of age. At baseline both groups were similar concerning the proportion of familial hypertrophic cardiomyopathy, concomitant moderate hypertension, prior syncope, left ventricular outflow obstruction, left ventricular end diastolic pressure, and left ventricular ejection fraction. Patients in group 2 had a lower interventricular septal thickness and more severe disease as measured by New York Heart Association (NYHA) functional class, exercise capacity, pulmonary artery mean pressure at workload, and cardiac index at peak exercise.

RESULTS

Median follow up was seven months after transcoronary ablation of septal hypertrophy. Both groups had a significant and similar improvement in basal and provokable obstruction, septal thickness, NYHA functional class, exercise tolerance, peak oxygen consumption, and pulmonary artery mean pressure at workload. Significant differences, compared with the younger group, were a higher proportion of persistent total atrioventricular block (5% v 17%, p = 0.015) and a slight decrease in left ventricular ejection fraction (3 (12) v -6 (11)%, p = 0.001) in the elderly, despite a trend to a lower induced peak creatine kinase activity (596 (339) v 491 (331) U/l, p = 0.051).

CONCLUSIONS

Short term results with transcoronary ablation of septal hypertrophy suggest that independent of a patient's age similar treatment strategies are justified in hypertrophic obstructive cardiomyopathy.

The use of cardioselective beta-blockers in a patient with idiopathic hypertrophic subaortic stenosis and chronic obstructive pulmonary disease

The beta-adrenergic receptor blocking drugs are commonly used in the treatment of patients with idiopathic hypertropic subaortic stenosis (IHSS). These drugs, however, are contraindicated in patients with chronic obstructive pulmonary disease (COPD). We report the anesthetic management of a patient with IHSS complicated by severe COPD. We concluded that the beta(1) selective, ultra-short acting beta-blocker, esmolol, can be used intraoperatively when both conditions are present. The pathophysiology and the commonly used anesthetic drugs and practices for treatment of patients with IHSS are reviewed.

Heart Failure with Normal Ejection Fraction

Heart failure with normal ejection fraction, also known as diastolic heart failure, is a major problem for patients and health-care providers and is a substantial expense to society. The main pathophysiologic processes involved are increased left ventricular stiffness and abnormal relaxation, with resulting impaired left ventricular filling. These processes typically displace the pressure-volume relationship in an upward direction, resulting in increased left ventricular end-diastolic, left atrial, and pulmonary capillary wedge pressures, leading to symptoms of pulmonary congestion. The most common clinical disorders leading to diastolic heart failure are 1) hypertension with concentric left ventricular hypertrophy, 2) coronary artery disease with decreased left ventricular compliance, 3) hypertrophic cardiomyopathy, and 4) aortic stenosis with concentric left ventricular hypertrophy. Echocardiography and cardiac catheterization with magnetic resonance imaging hold promise as future diagnostic tools. The approach to the treatment of diastolic heart failure is focused on four treatment goals: 1) persistent control of elevated blood pressure, with regression of left ventricular hypertrophy, 2) careful reduction of central blood volume (diuretics), 3) maintenance of atrial contraction and control of heart rate (beta-blockers, digoxin, atrioventricular pacing); and 4) improvement of left ventricular relaxation. There is currently no drug treatment specific for abnormal relaxation, although efforts are being made to develop such compounds. A promising future therapy includes agents that lyse advanced glycation end-products as an approach to relieving increased ventricular stiffness. In addition to pharmacotherapy, maintaining ideal body weight and a regular exercise program are also helpful in the treatment of diastolic heart failure. Although the overall prognosis of patients with diastolic dysfunction is more favorable than that of patients with systolic dysfunction, the frequency of treatment failure and recurrent symptoms underscores the need for further improvement in treatment of this condition.