Method and device for treating cardiac arrhythmias
a technology for arrhythmias and heart rhythms, applied in the field of medical treatments, can solve the problems of insufficient magnitude or timing of energy delivery, drawbacks of existing defibrillation systems, and cardiac arrhythmias are an important cause of morbidity and mortality, so as to achieve the effect of reducing or treating cardiac arrhythmias
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example 1
Reversible Conduction Block in Cardiac Tissue Using Sinusoidal Alternating Current Field Stimulation
[0085]The following experimental methods were followed in this example.
[0086]Cell culture was performed as follows. Neonatal rat ventricular myocytes (NRVMs) were dissociated from 2-day old Sprague-Dawley rat hearts with the use of the enzymes, trypsin and collagenase, as previously described (see, Iravanian et al., AJP Heart Circ., 285(1):H4449-56 (2003)). The resulting cell suspension was plated at high density onto 21 mm diameter plastic coverslips (106 myocytes per coverslip) to form monolayers that became confluent after 3-4 days of culture. Experiments were performed on days 6 to 8 after plating. For reentry experiments, prior to plating, a 4-mm diameter hole was punched in the coverslip.
[0087]Electrophysiological recording was performed as follows. Transmembrane voltage was recorded using contact fluorescent imaging as previously described (see, Entcheva et al., J Cardiovasc El...
example 2
AC Applied to Whole Hearts
[0105]This example presents data showing termination of fibrillation in whole guinea pig hearts in vivo upon application of AC.
[0106]Guinea pigs were perfused as Langendorff preparations. Hearts were stained with the voltage-sensitive dye di-4-ANEPPS (10 μmol / L) by direct coronary perfusion for 10 minutes. An EC uncoupler (diacetyl monoxime) was used to arrest mechanical deformation and the hearts were placed in a custom-built chamber that was attached to a micromanipulator. Optical action potential mapping was performed from 128 sites of the intact guinea pig heart. Total mapping field was Ian xl cm with an estimated depth of field of 0.2 mm. The ventricular epicardial surface was stimulated using bipolar electrodes to induce ventricular fibrillation. Two field electrodes placed on either side of the heart delivered the AC electric field.
[0107]Pulses of AC administered to whole guinea pig hearts was performed. As shown in FIG. 7, defibrillation of a whole ...
example 3
Administration of Ramped Waveform
[0108]This example presents data showing administration of high frequency AC having a ramped waveform to skeletal muscle of adult swine.
[0109]In experiments in adult swine, an accepted surrogate of shock-induced pain, the effect of high frequency AC on skeletal muscle stimulation was tested and compared with that observed during standard ICD shocks as control. Application of high frequency AC (1 kHz) ramped in amplitude from 0 to 100 V over 1 sec (FIG. 9A) to the hind limb produced a gradual tetanic muscle contraction without significant further muscle response to 400 V biphasic shock immediately following the high frequency AC ramp (FIG. 9B), whereas application of a 400 V standard biphasic shock alone elicited a sudden sharp contraction of the limb (FIG. 9C), like that seen during cardiac defibrillation. HFAC blunts the amplitude and especially the rate of force developed in skeletal muscle, which results in substantial mitigation of defibrillation...
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