Zion Sasson

Hypertrophic cardiomyopathy. The importance of the site and the extent of hypertrophy. A review

Hypertrophic cardiomyopathy is a diverse clinical and pathophysiologic entity that involves principally the left ventricle and is caused by asymmetric or concentric hypertrophy of unknown cause. If asymmetric, the hypertrophy is usually greatest in the ventricular septum, but variations occur in which the hypertrophy may be maximal at the apex, at the midventricular level, or, rarely, in the free wall of the left ventricle. Right ventricular involvement is usually less evident. The principal abnormality in systole is the obstruction to left ventricular outflow caused by upper septal hypertrophy narrowing the outflow tract and setting the stage for Venturi forces to cause systolic anterior motion of the anterior or posterior mitral leaflets. The time of onset and duration of mitral leaflet-septal contact determine the magnitude of the pressure gradient. Mitral regurgitation invariably accompanies the obstruction to outflow. Ventriculomyotomy-myectomy surgery, by thinning the septum and widening the outflow tract, abolishes the abnormal mitral leaflet motion and, consequently, the obstruction to outflow and the mitral regurgitation. This form of surgery more dramatically relieves the systolic abnormalities and the accompanying symptoms than any form of medical therapy available today. The extent of hypertrophy is believed to be the principal determinant of the impaired left ventricular relaxation and increased chambers stiffness (decreased compliance) that characterize diastole in hypertrophic cardiomyopathy. Relaxation is impaired by the contraction load (the obstruction), by a decrease in the principal relaxation loads, by a pathologic degree of nonuniformity of contraction and relaxation, and in all likelihood, by impaired inactivation of the biochemical processes responsible for contraction (? due to primary or ischemia-induced calcium overload). Calcium channel-blocking agents may dramatically improve left ventricular relaxation by speeding up the inactivation process, by decreasing the degree of nonuniformity, or by altering the contraction and relaxation loads in a favorable manner. Atrial and ventricular arrhythmias are responsible for a significant proportion of the morbidity and mortality, and their occurrence also appears to depend on the extent of hypertrophy. Thus, the major manifestations of hypertrophic cardiomyopathy in systole and diastole as well as the disturbances of rhythm appear to be related to the site and/or extent of the hypertrophic process.(ABSTRACT TRUNCATED AT 400 WORDS)

Insulin resistance is an important determinant of left ventricular mass in the obese.

BackgroundObesity in adults is associated with increased left ventricular (LV) mass. The mechanism for this is unclear, however. We tested the hypothesis that insulin resistance is an important independent contributing factor to LV mass in the healthy obese population. Methods and ResultsThe study population consisted of 40 normotensive, nondiabetic, otherwise healthy obese subjects with body mass index (BMI) >25 kg/m2. LV mass was echocardiographically determined according to the Penn convention, using the formula of Devereux and Reichek. Insulin resistance was assessed using indices derived from Intravenous Glucose Tolerance Test (IVGTT): insulin level at baseline, insulin level at 90 minutes of IVGTT (insulin-90), insulin integration over 90 minutes of IVGTT, and rate of glucose disposal (k value). Insulin-90 (r=.61, P=.0001), k value (r=.55, P=.003), insulin integration over 90 minutes (r=.46, P=.003), basal insulin (r=.44, P=.005), and BMI (r=.59, P=.0001) were all strongly correlated with LV mass by univariate analysis. No significant correlation was found with blood pressure or age. In multivariate regression analysis, only insulin-90 and k value correlated significantly with LV mass (P=.03, P=.02, respectively), accounting for 50% of the variance of LV mass, whereas the association with BMI became insignificant (P=.2). ConclusionsLV mass in the normotensive nondiabetic obese population is strongly associated with, and may be mediated by, the degree of insulin resistance and its associated hyperinsulinemia, independent of BMI and blood pressure.

ST-segment depression during sleep in obstructive sleep apnea

It was hypothesized that obstructive sleep apnea may precipitate myocardial ischemia, reflected by ST-segment depression, in some patients during sleep. Overnight sleep studies and simultaneous 3-channel Holter monitoring were performed on 23 consecutive patients with obstructive sleep apnea without a history of coronary artery disease. Each patient was randomly assigned to nasal continuous positive airway pressure for the first half of the night. An episode of significant ST depression was defined as > 1 mm from baseline for > 1 minute. The total duration (minutes) of ST depression was indexed to the total sleep time (minutes per hour of sleep). Seven patients (30%) had ST depression during sleep. In all 7 patients the duration of ST depression decreased during nasal continuous positive airway pressure (30 +/- 18 vs 11 +/- 13 minutes per hour of sleep) in association with a reduction in the apnea-hypopnea index (65 +/- 35 vs 7 +/- 6/hour), arousal index (49 +/- 14 vs 6 +/- 4/hour) and the duration that oxygen saturation was < 90% (44 +/- 27 vs 12 +/- 23% total sleep time). When patients were not on nasal continuous positive airway pressure, the apnea-hypopnea and arousal indexes were higher during periods of ST depression than when ST segments were isoelectric, whereas oxygen saturation was not different. These 7 patients underwent exercise testing, which was positive for inducible myocardial ischemia in 1 patient. It is concluded that ST depression is relatively common in patients with obstructive apnea during sleep and that the duration of ST depression is significantly reduced by nasal continuous positive airway pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Impairment of left ventricular diastolic function in systemic lupus erythematosus

Left ventricular (LV) diastolic performance was evaluated with pulsed-wave Doppler echocardiography in a cross-sectional population of patients with systemic lupus erythematosus (SLE) in search of subclinical myocardial involvement. Such involvement is reported to occur infrequently, despite pathohistologic evidence of myocarditis in up to 70% of patients with SLE. Thirty-five consecutive patients with SLE were evaluated, 14 with active and 21 with inactive disease, and were compared with 30 age-matched healthy control subjects. Twenty-six patients were restudied at 7 months. All had normal LV systolic function, normal pericardial and valvular structures, and no significant valvular regurgitation on Doppler echocardiography. In SLE patients with active disease, indexes of LV diastolic function differed significantly from the inactive group and from control subjects, with marked prolongation of isovolumic relaxation time (104 +/- 18 vs 74 +/- 13 ms, p = 0.0001), as well as reduced peak early diastolic filling velocity (E) (0.69 +/- 0.19 vs 0.83 +/- 0.17 ms, p = 0.01), reduced ratio of early to late diastolic flow velocity (E/A) (1.15 +/- 0.53 vs 1.47 +/- 0.35, p = 0.02), and prolonged mitral pressure halftime (74 +/- 14 vs 65 +/- 8 ms p = 0.01). Similar significant differences were found between the active and inactive SLE patient groups. SLE patients with inactive disease differed from control subjects in only mild prolongation of mitral pressure halftime. Abnormal prolongation of isovolumic relaxation (greater than 100 ms) was found to be the most useful marker of diastolic impairment, being present in 64% of SLE patients with active disease and in 14% of patients with inactive disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Antihypertensive Therapy on Glucose and Insulin Metabolism and on Left Ventricular Mass A Randomized, Double-Blind, Controlled Study of 21 Obese Hypertensives

BackgroundGlucose and insulin levels are associated with left ventricular mass (LVM) in insulin-resistant individuals. Antihypertensive drugs have different effects on glucose and insulin metabolism (GIM) and on LVM. To evaluate whether the effects of antihypertensive therapy on LVM are associated with its effects on GIM, we compared the effects of atenolol and perindopril on these parameters in a group of insulin-resistant, obese hypertensives . Methods and ResultsA total of 21 obese, nondiabetic hypertensives who were aged 55±12 years, had a body mass index of 32.8±5.0 kg/m2, were free of coronary or valvular heart disease, and had normal LV function were randomized to treatment with atenolol (n=11) or perindopril (n=10). Echocardiographic LVM corrected for height (LVM/height) and GIM (3-hour intravenous glucose tolerance test) were measured after 4 to 6 weeks of washout and 6 months of treatment. Baseline characteristics were similar in both groups. Atenolol and perindopril effectively reduced blood pressure (from 149±13/98±4 to 127±8/82±6 mm Hg and from 148±9/98±4 to 129±9/82±6 mm Hg, respectively, for the atenolol and perindopril groups;P =0.002). Atenolol significantly worsened GIM parameters, fasting glucose levels (5.3±0.9 to 6.0±1.5 mmol/L;P =0.003), fasting insulin levels (121±121 to 189±228 pmol/L;P =0.03), and most other relevant metabolic measures (P <0.05 for all). Perindopril did not affect GIM. Atenolol did not affect LVM/height (119±12 to 120±17 g/m;P =0.8), whereas perindopril significantly reduced LVM/height (120±13 to 111±19 g/m;P =0.04). ConclusionsIn obese, hypertensive individuals, adequate and similar blood pressure control was achieved with perindopril and atenolol. However, perindopril but not atenolol was associated with a more favorable GIM profile and led to a significant regression of LVM.

Strain, Strain Rate, and the Force Frequency Relationship in Patients with and without Heart Failure

BACKGROUND The aim of this study was to examine the effect of heart rate (HR) on indices of deformation in adults with and without heart failure (HF) who underwent simultaneous high-fidelity catheterization of the left ventricle to describe the force-frequency relationship. METHODS Right atrial pacing to control HR and high-fidelity recordings of left ventricular (LV) pressure were used to inscribe the force-frequency relationship. Simultaneous two-dimensional echocardiographic imaging was acquired for speckle-tracking analysis. RESULTS Thirteen patients with normal LV function and 12 with systolic HF (LV ejection fraction, 31 ± 13%) were studied. Patients with HF had depressed isovolumic contractility and impaired longitudinal strain and strain rate. HR-dependent increases in LV+dP/dt(max), the force-frequency relationship, was demonstrated in both groups (normal LV function, baseline to 100 beats/min: 1,335 ± 296 to 1,564 ± 320 mm Hg/sec, P < .0001; HF, baseline to 100 beats/min: 970 ± 207 to 1,083 ± 233 mm Hg/sec, P < .01). Longitudinal strain decreased significantly (normal LV function, baseline to 100 beats/min: 18.0 ± 3.5% to 10.8 ± 6.0%, P < .001; HF: 9.4 ± 4.1% to 7.5 ± 3.4%, P < .01). The decrease in longitudinal strain was related to a decrease in LV end-diastolic dimensions. Strain rate did not change with right atrial pacing. CONCLUSIONS Despite the inotropic effect of increasing HR, longitudinal strain decreases in parallel with stroke volume as load-dependent indices of ejection. Strain rate did not reflect the modest HR-related changes in contractility; on the other hand, the use of strain rate for quantitative stress imaging is also less likely to be confounded by chronotropic responses.

Relation Between Body Fat Distribution and Left Ventricular Mass in Men Without Structural Heart Disease or Systemic Hypertension

Abstract Left ventricular (LV) mass is a powerful, independent predictor of cardiovascular morbidity and mortality. 1 The association between obesity and LV mass has been well established, with the use of body mass index (BMI) as the measure of obesity. 2 However, BMI is limited in its ability to characterize obesity, because it is influenced by body proportion and reflects adipose tissue mass, as well as lean body mass. 3 In considering the contribution of adiposity per se to LV mass, it was suggested that descriptors of body fat distribution, such as waist circumference and waist-to-hip circumference ratio (WHR), may better correlate with LV mass. 2 Moreover, waist circumference and WHR, which mainly reflect the amount of intraabdominal fat, 4,5 have been shown to better correlate with cardiac morbidity and mortality, and established cardiac risk factors than do BMI and other measures of obesity. 6–9 The purpose of this study was to determine the relative importance of body fat distribution to LV mass. We hypothesized that body fat distribution, as assessed by waist circumference or WHR, accounts for a significantly greater degree of variance in LV mass than does the degree of obesity as assessed by BMI.

Heart Rate–Dependent Left Ventricular Diastolic Function in Patients With and Without Heart Failure

BACKGROUND Chronic heart rate (HR) reduction in the treatment of heart failure (HF) with systolic dysfunction is beneficial, but the immediate mechanical advantages or disadvantages of altering HR are incompletely understood. We examined the effects of increasing HR on early and late diastole in humans with and without HF. METHODS AND RESULTS We studied force-interval relationships of the left ventricle (LV) in 11 HF patients and 14 control subjects. HR was controlled by right atrial pacing, and LV pressure was recorded by a micromanometer-tipped catheter. The time constant of isovolumic relaxation (tau) was calculated, and simultaneous sonographic images were analyzed for LV volumes. The end-diastolic pressure-volume relationship (EDPVR) was analyzed with the use of a single-beat method. Tau was shortened in response to increasing HR in both groups; the slope of this relationship was steeper in HF than in control subjects. The predicted volume at a theoretic pressure of 0 mm Hg (V30) increased at higher HRs compared with baseline, shifting the predicted EDPVR compliance curve to the right in HF patients but not in control subjects. CONCLUSIONS In HF, changes in HR affect early relaxation and diastolic compliance to a greater extent than in control subjects. Our study reinforces current recommendations for HR-lowering drug treatment in HF.

Standards for Provision and Accreditation of Echocardiography in Ontario

In March of 2010, the Ontario Ministry of Health and Long-term Care and Ontario Medical Association jointly commissioned a Working Group to make recommendations regarding the provision and accreditation of echocardiographic services in Ontario. That commission undertook a process to examine all aspects of the provision, reporting and interpretation of echocardiographic examinations, including the echocardiographic examination itself, facilities, equipment, reporting, indications, and qualifications of personnel involved in the acquisition and interpretation of studies. The result was development of a set of 54 performance standards and a process for accreditation of echocardiographic facilities, initially on a voluntary basis, but leading to a process of mandatory accreditation. This article, and its accompanying Supplemental Material, outline the mandate, process undertaken, standards developed, and accreditation process recommended.

Left atrial appendage thrombus in atrial flutter with no associated heart disease

The risk of cardioembolic events and the role of anti-coagulation therapy in the management of patients with lone atrial flutter is not well defined in the medical literature. We report the case of an otherwise healthy 42-year-old man with chronic established atrial flutter, unassociated with any other heart disease or systemic illness, with transesophageal echocardiographic findings of a mobile left atrial appendage thrombus. The literature to date, potential mechanisms, and recommendations are discussed. The role of transesophageal electrocardiography and anticoagulation in atrial flutter may need to be considered more seriously, especially if atrial flutter has been present for a prolonged period of time.