Biochemical aspects of arrhythmogenesis and ventricular fibrillation

Opie, Lionel H.; Nathan, David G.; Lubbe, Welma

doi:10.1016/0002-9149(79)90055-9

Cited by 181 publications

(31 citation statements)

References 125 publications

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“…Raised cAMP concentrations result in an increase in intracellular calcium which may exacerbate ischemia. 21 Levosimendan, with its negligible effect on myocardial oxygen demand, is better tolerated by patients with ischemic cardiomyopathy, as demonstrated by an open-label dosecontrolled study in patients with AMI. 22 Moreover, a recent study demonstrated that levosimendan is safe in patients with acute coronary syndromes who underwent a percutaneous coronary intervention (PCI) and improves the function of stunned myocardium.…”

Section: Discussionmentioning

confidence: 97%

Comparison of Ischemic Side Effects of Levosimendan and Dobutamine with Integrated Backscatter Analysis

Duygu

Nalbantgil

Zoghi

et al. 2009

Clinical Cardiology

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Background: Levosimendan improves cardiac contractility without increasing oxygen consumption. However, its effects on ischemia were not supported with the utilization of a noninvasive parameter of myocardial characterization. Hypothesis: The changes observed in integrated backscatter (IBS) may be reflective of change in myocardial ischemia. In this study, the effect of levosimendan on ischemia detected by IBS was evaluated in patients with ischemic heart failure (HF). Methods: Patients who had LVEF <40% and NYHA III-IV symptoms of HF were included in this study. Patients were randomized to levosimendan (n = 21), or to dobutamine (n = 25) groups. The cyclic variation of integrated backscatter (CVIBS) was determined as the difference between the maximal and minimal values in a cardiac cycle, average of three consecutive beats. CVIBS was taken from the mid-anteroseptal, mid-inferior, and mid-posterolateral areas of the parasternal short axis images before the drug administration and at the end of the 24-hour infusion period. Results: Baseline characteristics and concomitant medications were similar in both groups. A significant reduction in CVIBS was detected in anteroseptal (7.6 ± 1.4 dB versus 5.9 ± 0.8 dB, p = 0.01), inferior wall (7.4 ± 0.8 dB versus 6.7 ± 1.5 dB, p = 0.03), and posterolateral wall (9.0 ± 1.2 dB versus 8.2 ± 0.6 dB, p = 0.04) after dobutamine administration, while no significant changes were observed in the levosimendan group in all walls. Conclusions: Unlike dobutamine, levosimendan may not induce myocardial ischemia as shown by CVIBS at commonly used dosages in the setting of decompensated HF without active ischemia.

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Section: Discussionmentioning

confidence: 97%

Comparison of Ischemic Side Effects of Levosimendan and Dobutamine with Integrated Backscatter Analysis

Duygu

Nalbantgil

Zoghi

et al. 2009

Clinical Cardiology

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“…Nevertheless, the decrease in the amplitude of MAP is probably caused by the decrease in the resting potential, because the amplitude of MAP markedly decreased at T4 after verapamil. It has been reported that acidosis and several metabolic factors besides K+ accumulation in the extracellular space also contribute to electrical abnormalities during ischaemia (Dower et aL, 1977a;Vogel & Sperelakis, 1977;Carmeliet, 1978;Opie, Nathan & Lubbe, 1979;Hill & Gettes, 1980;Morena, Janse, Folet, Krieger, Crijns & Durrer, 1980). Therefore, it is probable that verapamil attenuated these metabolic changes resulting in the inhibition of ST-T alternans and conduction abnormalities.…”

Section: Discussionmentioning

confidence: 99%

Effects of Calcium Antagonists on the Alternation of the St‐t Complex and Associated Conduction Abnormalities During Coronary Occlusion in Dogs

Hashimoto

Nakashima

1981

British J Pharmacology

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1 The effects of Ca2+-antagonists on the relationships between alternate changes in the ST-T complex in the epicardial electrogram, ST-T alternans, and associated excitation-conduction abnormalities during coronary occlusion were examined in anaesthetized dogs. 2 Epicardial unipolar electrograms, bipolar electrograms (BPEG) and monophasic action potentials (MAP) were recorded with unipolar, composite and suction electrodes, respectively. 3 ST-T alternans was associated with serious conduction delay. During the period of ST-T alternans, the amplitude of MAP changed alternately and the negative deflection of the ST-T complex was associated with a larger MAP. A depression of the TQ level and decrease in the resting potential of MAP were marked. 4 Verapamil (0.2 mg/kg) and diltiazem (0.5 mg/kg) inhibited ST-T alternans, conduction abnormalities, TQ depression and changes in MAP. However, after these drugs, the TQ depression and the decrease in the resting potential were evident after a longer period of occlusion at a time when ST-T alternans, conduction abnormalities and alternate changes in MAP were still inhibited. Dipyridamole (0.5 mg/kg) had no effect on either ST-T alternans or the conduction abnormalities.5 Verapamil and diltiazem inhibited ST-T alternans and the associated excitation and conduction abnormalities. The effects of these two drugs cannot be explained on the basis of attenuation of the decrease in the resting potential.

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“…The development of ventricular fibrillation is strengthened by the difference between the duration of the refractory period and irregular electrical activity in the various parts of the heart. The probability of the development of such irregular activity is increased by an increased resting excitability, a decreased conduction velocity, and an increase in automaticity (Fisch, 1973;Opie et al, 1979;Carmeliet, 1988). The resistance of the heart to these disorders is dependent on its electrical stability, which can be measured by several parameters such as the duration of the vulnerable period (Wegria et al, 1941;Axelrod et al, 1975), ventricular flutter threshold (Szekeres & Papp, 1967), excitability threshold (Jones & Klein, 1982), or ventricular fibrillation threshold (Wegria et al, 1941;Gerst et al, 1966).…”

Section: Introductionmentioning

confidence: 99%

“…The vulnerable duration period was prolonged during hypoventilation. These disorders can be explained by a sudden increase in extracellular K + concentration, which plays a crucial role in the changes in resting membrane potential, and can produce ectopic activity as well as inhibition of the rapid reaction (Opie et al, 1979). The rapid increase in extracellular K + concentration is the result of K ATP channel activation.…”

mentioning

confidence: 99%

Chronobiological Aspects of the Heart Rhythm Disorders at the Change of Pulmonary Ventilation in Rat Model

Švorc¹,

Marossy²,

Grešová³

et al. 2012

Cardiac Arrhythmias - New Considerations

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Biochemical aspects of arrhythmogenesis and ventricular fibrillation

Cited by 181 publications

References 125 publications

Comparison of Ischemic Side Effects of Levosimendan and Dobutamine with Integrated Backscatter Analysis

Comparison of Ischemic Side Effects of Levosimendan and Dobutamine with Integrated Backscatter Analysis

Effects of Calcium Antagonists on the Alternation of the St‐t Complex and Associated Conduction Abnormalities During Coronary Occlusion in Dogs

Chronobiological Aspects of the Heart Rhythm Disorders at the Change of Pulmonary Ventilation in Rat Model

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