Thresholds for premature ventricular contractions in frog hearts exposed to lithotripter fields

Dalecki, Diane; Keller, Bradley B.; Carstensen, Edwin L.; Neel, Darcy S.; Palladino, Joseph L.; Noordergraaf, Abraham

doi:10.1016/0301-5629(91)90133-h

Cited by 55 publications

(27 citation statements)

References 14 publications

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“…The pressure threshold for cardiac stimulation by shock waves was in the range of 5-10MPa (Dalecki et al 1991) or 1 MPa (Delius et al 1994a). Fast shock wave administration at a rate of 100Hz induced arrhythmias even far away from the focus where single pulses had nearly no stimulating activity.…”

Section: Cardiac Arrhythmia Inductionmentioning

confidence: 99%

Medical applications and bioeffects of extracorporeal shock waves

Delius¹

1994

Shock Waves

163

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Abstract. Lithotripter shock waves are pressure pulses of microsecond duration with peak pressures of 35-120MPa fotlowed by a tensile wave. They are an established treatment modality for kidney and gallstone disease. Further applications are pancreatic and salivary stones, as well as delayed fracture healing. The latter are either on their way to become established treatments or are currently under investigation. Shock waves generate tissue damage as a side effect which has been extensively investigated in the kidney, the liver, and the gallbladder. The primary adverse effects are local destruction of blood vessels, bleedings, and formation of blood clots in vessels. Investigations on the mechanism of shock wave action revealed that lithotripters generate cavitation both in vitro and in vivo. An increase in tissue damage at higher pulse administration rates, and also at shock wave application with concomitant gas bubble injection suggested that cavitation is a major mechanism of tissue damage. Disturbances of the heart rhythm and excitation of nerves are further biological effects of shock waves; both are probably also mediated by cavitation. On the cellular level, shock waves induce damage to cell organelles; its extent is related to their energy density. They also cause a transient increase in membrane permeability which does not lead to celJ death. Administered either alone or in combination with drugs, shock waves have been shown to delay the growth of small animal tumors and even induce tumor remissions. While the role of cavitation in biological effects is widely accepted, the mechanism of stone fragmentation by shock waves is still controversial. Cavitation is detected around the stone and hyperbaric pressure suppresses fragmentation; yet major cracks are formed early before cavitation bubble collapse is observed. The latter has been regarded as evidence for a direct shock wave effect.

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Section: Cardiac Arrhythmia Inductionmentioning

confidence: 99%

Medical applications and bioeffects of extracorporeal shock waves

Delius¹

1994

Shock Waves

163

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“…Diagnostic applications seek to minimize the interaction between the acoustic field and tissues, whereas its therapeutic use exploits direct bioeffects, such as acoustic cavitation, radiation force, radiation torque, and acoustic streaming (9). The cardiac effects during the clinical use of ultrasound became apparent through observation of a high incidence of arrhythmic events during lithotripsy treatments, which initially occurred in as many as 80% of patients undergoing this therapy (10,13). Heating alone cannot explain the source of this effect, and oscillatory wave pressure accounts for very minimal tissue displacement at a cellular level (11,46).…”

mentioning

confidence: 99%

Ultrasound-induced modulation of cardiac rhythm in neonatal rat ventricular cardiomyocytes

Fleischman¹,

Vecchio

Sunny

et al. 2015

Journal of Applied Physiology

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Fleischman A, Vecchio C, Sunny Y, Bawiec CR, Lewin PA, Kresh JY, Kohut AR. Ultrasound-induced modulation of cardiac rhythm in neonatal rat ventricular cardiomyocytes. J Appl Physiol 118: 1423-1428, 2015. First published April 9, 2015 doi:10.1152/japplphysiol.00980.2014.-Isolated neonatal rat ventricular cardiomyocytes were used to study the influence of ultrasound on the chronotropic response in a tissue culture model. The beat frequency of the cells, varying from 40 to 90 beats/min, was measured based upon the translocation of the nuclear membrane captured by a high-speed camera. Ultrasound pulses (frequency ϭ 2.5 MHz) were delivered at 300-ms intervals [3.33 Hz pulse repetition frequency (PRF)], in turn corresponding to 200 pulses/min. The intensity of acoustic energy and pulse duration were made variable, 0.02-0.87 W/cm 2 and 1-5 ms, respectively. In 57 of 99 trials, there was a noted average increase in beat frequency of 25% with 8-s exposures to ultrasonic pulses. Applied ultrasound energy with a spatial peak time average acoustic intensity (Ispta) of 0.02 W/cm 2 and pulse duration of 1 ms effectively increased the contraction rate of cardiomyocytes (P Ͻ 0.05). Of the acoustic power tested, the lowest level of acoustic intensity and shortest pulse duration proved most effective at increasing the electrophysiological responsiveness and beat frequency of cardiomyocytes. Determining the optimal conditions for delivery of ultrasound will be essential to developing new models for understanding mechanoelectrical coupling (MEC) and understanding novel nonelectrical pacing modalities for clinical applications.

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“…The pressure threshold for this appears to be in the range of 1 to 10 MPa. 26,27 When multiple shock waves are administered at high frequency (100 Hz), arrhythmias can occur away from the focus. Stimulation of peripheral nerves also occurs within the focus of the …”

Section: Effects Of Shock Waves On Soft Tissuesmentioning

confidence: 99%