Clinical utility of a magnetic resonance-conditional pacemaker in a patient with cardiac sarcoidosis.

We herein present a case of cardiac sarcoidosis with atrioventricular (AV) block that was evaluated using magnetic resonance imaging (MRI) before and after pacemaker implantation. An echocardiogram showed wall thinning in the basal septum. MRI showed late gadolinium enhancement in the interventricular septum and right ventricle.

Peripheral oxytocin treatment ameliorates obesity by reducing food intake and visceral fat mass.

Recent studies suggest that oxytocin (Oxt) is implicated in energy metabolism. We aimed to explore acute and sub-chronic effects of peripheral Oxt treatment via different routes on food intake and energy balance. Intraperitoneal (ip) injection of Oxt concentration-dependently decreased food intake in mice.

Long-term follow-up of "reversible" dilated cardiomyopathy with improvement of cardiac sympathetic nerve activity after cardiac resynchronization therapy (CRT): Do "CRT superresponders" have "dyssynchrony-induced cardiomyopathy"?

We report a case of idiopathic dilated cardiomyopathy with severe heart failure and complete left bundle branch block (CLBBB) which exhibited an excellent response to cardiac resynchronization therapy (CRT). A 71-year-old male had been treated for 9 years with medication for chronic heart failure. He was referred to hospital with a complaint of dyspnea.

Myocardial stunning with partial aneurysmal formation generated during the recovering process of tachycardia-induced cardiomyopathy.

We report a rare case of tachycardia-induced cardiomyopathy with apical stunning followed by partial aneurysmal formation. A 66-year-old male was admitted because of dyspnea and palpitation. Electrocardiogram showed persistent tachycardia due to atrial flutter.

Energy metabolism after ischemic preconditioning in streptozotocin-induced diabetic rat hearts.

Objectives: The aim of this study was to compare the cardioprotective effects of preconditioning in hearts from streptozotocin-induced diabetic rats with its effects in normal rat hearts.

Background: The protective effect of ischemic preconditioning against myocardial ischemia may come from improved energy balance. However, it is not known whether preconditioning can also afford protection to diabetic hearts.

Effect of ischemic preconditioning on mitochondrial oxidative phosphorylation and high energy phosphates in rat hearts.

The ability of ischemic preconditioning (IP) to protect the myocardium against prolonged ischemia may derive from improved energy balance. We therefore examined myocardial energy metabolism and mitochondrial oxidative phosphorylation in isolated perfused rat hearts which were either subjected (IP group), or not subjected (control group), to preconditioning prior to 30 min sustained ischemia and 30 min reperfusion. Preconditioning was achieved with two cycles of 5 min ischemia followed by 5 min reperfusion.

Kinetics of frequency-dependent conduction delay by class I antiarrhythmic drugs in human atrium.

We investigated use-dependent prolongation of interatrial conduction time (IACT) by class I antiarrhythmic drugs in 16 patients. Changes in IACT at the initiation of atrial pacing were used to evaluate the onset kinetics. We examined recovery kinetics by giving a single extra stimulus with a varying coupling interval after discontinuing train stimulation.

Effect of nicorandil on cardiac dysfunction during reperfusion in normotensive and spontaneously hypertensive rats.

The cardioprotective effect of nicorandil, an opener of ATP-sensitive potassium channels, was studied in the isolated perfused hearts of the spontaneously hypertensive rat (SHR) and normotensive Wistar-Kyoto (WKY) rat. The hearts were subjected to 30 min of global ischemia followed by 30 min of reperfusion. Controls received no drug.

Effects of ischemic preconditioning on the release of cardiac troponin T in isolated rat hearts.

The aim of this study was to examine the effect of ischemic preconditioning on the releases of cardiac troponin T (TnT) during reperfusion in isolated rat hearts. Experiments were done on 22 rat hearts, which were perfused according to the method of Langendorff and were divided into the control group (n = 14) and the preconditioning group (n = 8). Double 5 min of ischemia each followed by 5 min reflow were applied as ischemic preconditioning.

Effects of repeated ischemia on release kinetics of troponin T, creatine kinase, and lactate dehydrogenase in coronary effluent from isolated rat hearts.

We studied the release kinetics of cardiac troponin T (TnT) from coronary effluent in a re-stenosis model of 13 isolated rat hearts. After a 20-min period of global ischemia, we reperfused the hearts for 60 min according to the method of Langendorff. A second period of global ischemia was then induced for 5 min (protocol A) or 20 min (protocol B), followed by a second 60-min period of reperfusion.

[Frequency dependent prolongation of inter-atrial conduction time by mexiletine in human atrium].

To investigate frequency dependent conduction slowing by mexiletine in the human atrium, we examined inter-atrial conduction time (IACT) at different stimulation frequencies (100/min to 220/min) in 13 patients with paroxysmal atrial fibrillation (Paf) and 7 patients without Paf. IACT was prolonged as the stimulation frequency was increased, and either before or after mexiletine administration IACT was longer in the Paf group (max 114 +/- 9 msec, p < 0.01, mean +/- SD) at any stimulation frequency than in the non-Paf group (max 100 +/- 8 msec).

[Effect of pilsicainide hydrochloride on atrial fibrillation threshold].

To inventigate the electrophysiologic effects of pilsicainide hydrochloride on atrial fibrillation, we compared atrial fibrillation threshold (AFT), right atrial effective refractory period (RAERP), and inter-atrial conduction time (Inter-ACT) before and after the administration of pilsicainide in 12 patients with lone paroxysmal atrial fibrillation. The following electrophysiologic study was performed before and after the administration of the drug as the paced cycle length of 500msec. First, RAERP was measured.

Effects of caffeine on ischemia-reperfusion injury in isolated rat hearts.

Cardiac sarcoplasmic reticulum (SR) plays an important role in regulation of the intracellular Ca2+ concentration. It is well known that intracellular Ca2+ overload is one cause of reperfusion injury. Thus, it is predicted that reperfusion injury of myocardium can be prevented by eliminating the Ca2+ overload.

Release kinetics and correlation with hemodynamic dysfunction of cardiac troponin T in coronary effluent from isolated rat hearts during reperfusion.

Previously, we reported that cardiac troponin T (TnT) can be detected and measured in coronary effluent from isolated rat hearts during hypoxia. The present study was designed to evaluate the release kinetics of TnT from post-ischemic rat hearts. Using the Langendorff technique, the hearts were reperfused for 4 h after 20 min or 60 min of global ischemia.

Electrophysiological effects of flecainide acetate on stretched guinea pig left atrial muscle fibers.

The electrophysiological effects of flecainide acetate (3 x 10(-6) M) on stretched atrial tissue were investigated using guinea-pig left atrial muscle fibers. Before stretching, the resting membrane potential was not affected by flecainide at 1 Hz, although the overshoot potential (Eov) and the action potential duration at 50% repolarization (APD50) were slightly but significantly decreased by 2 +/- 1 mV and 2 +/- 1 msec, respectively. The effective refractory period (ERP) was increased by 3 +/- 1 msec.

Effects of pilsicainide on the atrial fibrillation threshold in guinea pig atria. A comparative study with disopyramide, lidocaine and flecainide.

The effects of pilsicainide, a new class Ic antiarrhythmic agent, on the atrial fibrillation threshold (AFT), the atrial effective refractory period (ERP), and the interatrial conduction time (ACT) in Langendorff-perfused guinea pig hearts were investigated. These effects were compared with those of disopyramide, lidocaine and flecainide. Whole guinea pig heart was perfused with Tyrode's solution containing acetylcholine (3 x 10(-7) M).

[Electrophysiologic effects of flecainide on guinea pig atrium].

We investigated the effects of flecainide on guinea pig atrial muscle. Using Langendorff's method, the whole heart of a guinea pig was perfused with Tyrode's solution containing acetylcholine (3 x 10(-7) M). Then, with right atrial extrastimulus and high frequency pacing method, the following values were measured before and after administration of flecainide (10(-7)-10(-5) M).

Acute and subacute effects of doxorubicin on postextrasystolic potentiation in guinea pig papillary muscles.

To investigate the effects of doxorubicin on postextrasystolic potentiation (PESP), isolated guinea pig papillary muscles were field-stimulated and the resulting isometric force was recorded. Postextrasystolic contraction was evoked following trains of 37 regular stimulations. The effects of acute doses of doxorubicin (0.

Release kinetics of cardiac troponin T in coronary effluent from isolated rat hearts during hypoxia and reoxygenation.

A newly developed troponin T (TnT) test for the detection of myocardial cell necrosis has been reported to be very efficient in the detection of acute myocardial infarction. The aim of the present study was to determine whether cardiac TnT in coronary effluent from isolated heart perfused with albumin-free perfusion medium could be detected using the enzyme-linked immuno-sorbent assay developed by Katus et al. Isolated rat hearts were perfused according to the method of Langendorff.

Acute effects of doxorubicin on skinned cardiac muscle fibres of guinea pigs.

Objective: The aim was to examine the effect of doxorubicin on spontaneous cyclic Ca2+ release from the sarcoplasmic reticulum of skinned fibres, as measured by isometric tension development in EGTA free, Ca2+ free solution.

Methods: Experiments were done on fragments of papillary muscles from the right ventricles of guinea pigs. Skinned fibres were prepared by treatment with saponin.

Effects of reduction of contractile work on mechanical function in post-hypoxic guinea pig papillary muscles and on myocardial energy metabolism in post-ischemic rat hearts.

This study was designed to investigate effects of quiescence by cessation of electrical stimulation during the first stage of reoxygenation on recovery of mechanical function from hypoxia-induced contractile dysfunction in papillary muscles and effects of the absence of cardiac output on myocardial energetic metabolism of post-ischemic hearts. (1) Regular contractions and postextrasystolic contraction were evoked. After 120 min hypoxia, muscles were reoxygenated.

Effects of hypoxia and reoxygenation on steady-state and potentiated contractions in papillary muscle of guinea pigs.

We studied the effects of hypoxia and reoxygenation on steady-state contractions and potentiated contractions of papillary muscles of guinea pigs. Isometric tension was measured while 120 min periods of hypoxia and reoxygenation were repeated twice. Reoxygenation after the first period of hypoxia induced a gradual recovery in steady-state contractions and a rapid recovery in potentiated contractions from the first hypoxia-induced contractile depression.

Effect of manidipine on cardiac hypertrophy and coronary circulation in DOCA/salt hypertensive rats.

The effect of manidipine on cardiac hypertrophy, coronary circulation, left ventricular weight and maximal coronary flow in hypertension was measured in DOCA/salt treated systolic hypertensive rats with and without manidipine treatment. Normotensive rats were used as controls. After feeding with 0.

[Effects of ouabain, caffeine, and diltiazem, on spontaneous cyclic Ca2+ release from sarcoplasmic reticulum in the skinned papillary muscles of guinea pigs].

The aim of this study was to assess whether ouabain has a direct action on the sarcoplasmic reticulum (SR) sufficient to be responsible for the mechanism of the inotropic action, and whether caffeine and diltiazem, which inhibit ouabain-induced afterpotential and after-contraction, can inhibit the effects of ouabain on the SR. As one of the functions of SR, spontaneous cyclic contractions (cyclic Ca2+ release from the SR) in saponin-treated skinned fibers of guinea pig papillary muscles were used. Ouabain 10(-9)-10(-7) M increased the frequency of cyclic contractions and induced an incomplete muscle relaxation.