Unrecognized left ventricular dysfunction in an apparently healthy cocaine abuse population

To determine the frequency and severity of clinically unrecognized left ventricular (LV) dysfunction related to cocaine use, 84 asymptomatic cocaine abusers underwent cardiac evaluation which included chest x-ray, electrocardiography (ECG), and radionuclide angiography after a two-week abstinence from cocaine use. LV dysfunction was discovered in 6/84 (7%). Regional wall motion abnormalities suggesting a localized myocardial abnormality were found in 2, whereas an ejection fraction less than 50% suggesting a more global process was noted in 4. An abnormal chest x-ray was found in only 1 subject and none had abnormal ECGs. In each of these cases, repeated and protracted use of cocaine was documented and the suggestion of cardiac dysfunction was supported by at least one other independent abnormal finding. In these 6 cases, the dysfunction was clinically unrecognized and unsuspected after routine evaluation. The significance of subclinical LV dysfunction in this population has not been determined and requires long-term study.     

Characterization of the right ventricular substrate participating in postinfarction ventricular tachycardia

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Capillary surface area is reduced and tissue thickness from capillaries to myocytes is increased in the left ventricle of streptozotocin-diabetic rats

Summary The left ventricles of normal and diabetic rats, fixed by vascular perfusion were examined using modern stereological techniques to quantify changes in the morphology accompanying streptozotocin-induced diabetes. The heart weight to body weight ratio increased in diabetic rats whilst left ventricular volume remained unchanged. Papillary muscles from the diabetic animals showed prolonged time to peak tension and relaxation, and altered sensitivity to adrenalin and calcium. The apparent cardiomyopathy observed when body weight loss exceeds heart weight loss in experimental diabetes was accompanied by specific pathological changes in the composition of the left ventricle. In the diabetic animals the volume of extracellular components increased threefold and the volume of capillaries fell. The surface density and total surface area of capillaries was reduced, and oxygen diffusion distance to myocyte mitochondria increased. The volume fraction of myocyte mitochondria was reduced during streptozotocin-induced diabetes.Abbreviations XSA cross-sectional area     

小儿心肌疾病抗肌球蛋白抗体和粒细胞-巨噬细胞集落刺激因子的研究

为探讨病毒性心肌炎（VMC）和扩张型心肌病（DCM）发病的自身免疫机制，采用酶联免疫吸附和放射免疫技术检测30例VMC、14例DCM患儿血浆中抗肌球蛋白抗体和粒细胞-巨噬细胞集落刺激因子（GM－CSF）。结果：VMC和DCM患儿抗肌球蛋白抗体和GM－CSF的阳性率均为54．5％（24／44），而正常对照组分别为4．0％（1／25）和8．0％（2／25）（均P＜0．01），且抗肌球蛋白抗体与GM－CSF的血浆水平有正相关性（r＝0．3583，P＜0．05）。提示：抗肌球蛋白抗体和GM－CSF均参与了VMC和DCM的发病，与心肌的自身免疫损伤过程有关。     

Clinical and echocardiographic aspects of mid-ventricular hypertrophic cardiomyopathy

Three cases of patients with hypertropic cardiomyopathy, apical aneurysm, and mid-ventricular obstruction are presented. Two patients were diagnosed first by two-dimensional and Doppler echocardiography, which showed mid-ventricular obliteration, characteristic hourglass image, and paradoxic jet flow. One patient with suboptimal echocardiogram was necessary to perform contrast echocardiogram. Clinical picture was characterized by angina and dyspnea. Thallium myocardial imaging revealed perfusion abnormalities in apical region, ischemia or necrosis. Cardiac catheterism showed mid-ventricular obliteration and significant intraventricular gradient and coronary arteries angiography without lesions.     

Human homozygous R403W mutant cardiac myosin presents disproportionate enhancement of mechanical and enzymatic properties

Familial hypertrophic cardiomyopathy (FHC) is associated with mutations in 11 genes encoding sarcomeric proteins. Most families present mutations in MYBPC3 and MYH7 encoding cardiac myosin-binding protein C and beta-myosin heavy chain. The consequences of MYH7 mutations have been extensively studied at the molecular level, but controversial results have been obtained with either reduced or augmented myosin motor function depending on the type or homogeneity of myosin studied. In the present study, we took advantage of the accessibility to an explanted heart to analyze for the first time the properties of human homozygous mutant myosin. The patient exhibited eccentric hypertrophy with severely impaired ejection fraction leading to heart transplantation, and carries a homozygous mutation in MYH7 (R403W) and a heterozygous variant in MYBPC3 (V896M). In situ analysis of the left ventricular tissue showed myocyte disarray and hypertrophy plus interstitial fibrosis. In vitro motility assays showed a small, but significant increase in sliding velocity of fluorescent-labeled actin filaments over human mutant cardiac myosin-coated surface compared to control (+18%; P<0.001). Mutant myosin exhibited a large increase in maximal actin-activated ATPase activity (+114%; P<0.05) and Km for actin (+87%; P<0.05) when compared to control. These data show disproportionate enhancement of mechanical and enzymatic properties of human mutant myosin. This suggests inefficient ATP utilization and reduced mechanical efficiency in the myocardial tissue of the patient, which could play an important role in the development of FHC phenotype.     

Myocardial involvement in acromegaly

We recently encountered a case of an acromegalic patient with congestive heart failure and secondary cardiomyopathy. Cardiac biopsies were available in addition to autopsy material. This enabled us to perform electron microscopical studies which have hitherto not been reported. This may help to clarify the relationship between these two conditions and reveal specific characteristics.