Dennis L. Rollins

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BACKGROUND Shocks that have defibrillated spontaneous ventricular fibrillation (VF) during acute ischemia or reperfusion may seem to have failed if VF recurs before the ECG amplifier recovers after shock. This could explain why the defibrillation threshold (DFT) for spontaneous VF appears markedly higher than for electrically induced VF. METHODS AND(More)
The characteristics of spontaneous cardiac arrhythmias leading to sudden cardiac death are largely unknown. To study arrhythmias in animal models, an eight-channel implantable radio telemetry system has been developed to record continuously cardiac electrograms over a period of weeks to months, with maintenance restricted to changing batteries. The inputs(More)
INTRODUCTION The purpose of this investigation was to study the transmembrane potential changes (delta Vm) during extracellular electrical field stimulation. METHODS AND RESULTS Vm was recorded in seven guinea pig papillary muscles in a tissue bath by a double-barrel microelectrode with one barrel in and the other just outside a cell while shocks were(More)
OBJECTIVES The purpose of this study was to determine if the defibrillation threshold (DFT) is lower during the first few cycles of ventricular fibrillation (VF) than after 10 s of VF and, if so, if the effect is caused by local or global factors. BACKGROUND The DFT may be low very early during VF because: (1) for the first few cycles VF arises from a(More)
The ultimate value of profundaplasty in the management of lower extremity ischemia was determined by multifactoral analysis of 239 operated limbs in 209 patients followed up to 110 months. In patients who underwent operation for claudication (n=83), patency without the need for subsequent revision or distal bypass was achieved in 77% at 5 years. By(More)
INTRODUCTION Recent studies showed that pacing atrial and ventricular fibrillation (VF) is possible. The studies presented here determined which parameters influence the efficacy of a pacing train to capture fibrillating ventricular myocardium. Electrode type, current strength, order of pacing trains, polarity, and VF morphology preceding the pacing trains(More)
While it has been shown that pacing during ventricular fibrillation (VF) can capture a portion of the epicardium, little is known about the characteristics of the area captured or about whether adaptively changing the pacing rate during VF will increase the area captured. In six open-chested pigs, pacing during VF was performed from the center of a plaque(More)
INTRODUCTION The relative importance of nonuniform dispersion of refractoriness, steep restitution slopes, and anatomic heterogeneities in causing conduction block during ventricular fibrillation (VF) remains unknown. METHODS AND RESULTS In six open-chest pigs, ventricular refractoriness and restitution curves were estimated from activation recovery(More)
An intelligent multichannel stimulator (IMS) has been designed and built for use in a cardiac research environment. The device is capable of measuring and responding to cardiac electrophysiological phenomena in real time with carefully timed and placed electrical stimuli. The system consists of 16 channels of sense/stimulation electronics controlled by a(More)
The concept of the profunda artery as a collateral system is very useful in determining which patients may benefit from profundaplasty. When hemodynamic profunda stenosis is associated with combined aortoiliac and superficial femoral artery occlusive disease, profundaplasty as an adjunct to an arterial inflow procedure is highly successful. It is most(More)