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At least 109 records · Page 6Linked to original sources
PubMed1995

Increased endothelin-1 gene expression in the endothelium of coronary arteries and endocardium in the DOCA-salt hypertensive rat.

Endothelin-1 (ET-1) is a potent vasoconstrictor and inotropic agent which may also induce cell hypertrophy. The role of ET-1 in ventricular hypertrophy in hypertension is unknown. We investigated ET-1 gene expression and immunoreactive ET-1 (ir-ET-1) concentration in the heart of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. To identify the cellular sites of ET-1 production in the heart, we performed in situ hybridization histochemistry. DOCA-treated rats which underwent unilateral nephrectomy (Uni-Nx) or not, exhibited mild systolic blood pressure elevation and ventricular hypertrophy. Blood pressure elevation and cardiac hypertrophy were more severe in DOCA-salt hypertensive rats. Ventricular ET-1 mRNA was similar in Uni-Nx control and DOCA-treated rats by Northern blot analysis, whereas in DOCA-salt hypertensive rats it was significantly increased. Ir-ET-1 concentration was also enhanced in ventricles from DOCA-salt hypertensive rats compared with Uni-Nx control rats. In situ hybridization histochemistry using a 35S-labelled complementary RNA ET-1 probe demonstrated that the level of ET-1 mRNA transcripts was increased exclusively in endothelial cells of large epicardial and small intramyocardial coronary arteries and in areas of the endocardium, but not significantly in myocardial cells of either the atria or ventricles. Enhanced ET-1 production may contribute to vascular changes, both structural and functional, in the heart in this model of hypertension in the rat, but probably does not contribute to the severe cardiac hypertrophy found in DOCA-salt hypertensive rats.

Animals↗
PubMedDate not supplied

Cardiac tuberculosis: TB of the endocardium.

Tuberculosis involving the endocardium is extremely rare. The diagnosis is usually made during autopsy. Often there is involvement of other parts of the heart as well as other regions of the body. The infection is a result of direct extension from the myocardium or hematogenous spread. Two cases of disseminated tuberculosis with endocardial involvement are reported. In Case 1 miliary tuberculosis was diagnosed during life but the patient succumbed to extensive disease on the third hospital day. The patient in Case 2 presented with congestive cardiac failure and the possibility of tuberculosis was not suspected during life.

Aged↗
PubMed2006

Steeper restitution slopes across right ventricular endocardium in patients with cardiomyopathy at high risk of ventricular arrhythmias.

Steep action potential duration (APD) restitution slopes (>1) and spatial APD restitution heterogeneity provide the substrate for ventricular fibrillation in computational models and experimental studies. Their relationship to ventricular arrhythmia vulnerability in human cardiomyopathy has not been defined. Patients with cardiomyopathy [left ventricular (LV) ejection fraction <40%] and no history of ventricular arrhythmias underwent risk stratification with programmed electrical stimulation or T wave alternans (TWA). Low-risk patients (n = 10) had no inducible ventricular tachycardia (VT) or negative TWA, while high-risk patients (n = 8) had inducible VT or positive TWA. Activation recovery interval (ARI) restitution slopes were measured simultaneously from 10 right ventricular (RV) endocardial sites during an S1-S2 pacing protocol. ARI restitution slope heterogeneity was defined as the coefficient of variation of slopes. Mean ARI restitution slope was significantly steeper in the high-risk group compared with the low-risk group [1.16 (SD 0.31) vs. 0.59 (SD 0.19), P = 0.0002]. The proportion of endocardial recording sites with a slope >1 was significantly larger in the high-risk patients [47% (SD 35) vs. 13% (SD 21), P = 0.022]. Spatial heterogeneity of ARI restitution slopes was similar between the two groups [29% (SD 16) vs. 39% (SD 34), P = 0.48]. There was an inverse linear relationship between the ARI restitution slope and the minimum diastolic interval (P < 0.001). In cardiomyopathic patients at high risk of ventricular arrhythmias, ARI restitution slopes along the RV endocardium are steeper, but restitution slope heterogeneity is similar compared with those at low risk. Steeper ARI restitution slopes may increase the propensity for ventricular arrhythmias in patients with impaired left ventricular function.

Adult↗
PubMed1979

Time course of infarct growth toward the endocardium after coronary occlusion.

Transmembrane potentials and ultrastructure of subendocardial Purkinje and ventricular muscle fibers, isolated 1, 3, 5, 6, 14, and 24 h after coronary occlusion were investigated. Action potentials were recorded from progressively fewer layers of muscle cells as the age of the infarct increased. At 14 h little viable muscle remained. The decrease in the number of electrophysiologically viable muscle fibers correlated with structural evidence that the infarct moved with time toward the endocardial surface until only viable Purkinje fibers remained. Purkinje and surviving ventricular muscle fibers demonstrated a progressive decrease in resting potential, action potential amplitude, and Vmax and a progressive increase in action potential duration. Spontaneous diastolic depolarizations were found in Purkinje fibers only in 24-h infarcts and occasionally in cells deep to the endocardial surface, which may have been muscle cells. We hypothesize that during the first 24 h after coronary occlusion arrhythmias originate near the interface of infarcted and ischemic myocardium. As this interface moves toward the endocardium, this site of origin of arrhythmias moves with it until the Purkinje network is reached.

Animals↗
PubMed1990

Reticulin antibodies: relationship with endocardium-vessel-interstitium antibodies and heterophilic antibodies.

1. Indirect immunofluorescence was used to compare reticulin antibodies, endocardium-vessel-interstitium (EVI) antibodies and heterophilic antibodies in serum samples from patients with degenerative and inflammatory diseases, Chagas' disease, or paracoccidioidomycosis and from healthy blood donors. 2. The antigen substrates used were rat, mouse and human liver for reticulin antibodies, mouse and human heart and skeletal muscle for EVI factor, and rat heart and rat, mouse and human kidney and stomach for heterophilic antibodies. 3. The three antibodies produced extremely similar fluorescent patterns and were present simultaneously in a large proportion of reticulin-positive serum samples. 4. The three antibodies were significantly absorbed by heterophilic antigens such as sheep and rat red blood cells and guinea pig kidney, by Trypanosoma cruzi (an antigen associated with EVI factor) and by Paracoccidioides brasiliensis. However, they did not react with several human tissues. 5. These results suggest that reticulin and EVI antibodies can be considered to be heterophilic antibodies.

Animals↗
PubMed1990

[Maturation of the electrode-endocardium interface].

It's largely known that the implanted lead in the endocardium develops an inflammation and posterior fibrosis of the cardiac tissue, increasing the stimulation threshold. It's also demonstrated that the chronic threshold values keep relation with the electrode surface area. There are several factors in the fibrosis genesis according mechanical of physical properties of the lead, such as tension, tip design, surface area and the patient reaction to a foreign body. Electrical factor is not yet sufficiently studied. We developed an experimental study in 12 dogs, separated in two groups (four explanted at 8 days or subacute group, and eight explanted at 35 days or chronic group), looking for a correlation between current density crossing the interface endocardial-electrode and the posterior fibrosis. The mechanical factor was minimized by using small surface area electrodes, with little tension. Three leads were implanted in each dog, connected respectively to 0, 2.5 and 5 volts. The simultaneous working of two pacemakers in the same dog, was possible by programming one of them in VVI at 140 per minute, and the other in VOO at 75. The tirht lead was implanted as a reference. The threshold pacing values, in voltage and in current, the R wave and impedance were measured at implant and at explant of the leads. Differences statistically significative were observed between reference electrodes and electrical active ones, according their current density. The leads stimulating with great current density (more voltage) generated more fibrosis and therefore higher pacing threshold values and lower R waves and impedances. The convenience to stimulate at low voltages was seen.

Animals↗
PubMedDate not supplied

[Evaluation of the suitability of the electrocardiosignal, derived from the right ventricular endocardium, for regulating an electrocardiostimulator].

All parameters of electrocardiosignal taken off the right ventricle endocardium are to be known for the development of the circuits for R-wave separation and provision of reliable cardiostimulation with biological control. This is the input signal of cardiostimulator with biocontrol. Methodical questions of recording this signal by means of Soviet electrodes, results of investigation and statistical processing of the signal parameters are reported.

Adult↗