TRAPEZOIDAL WAVESHAPE DEFIBRILLATOR

• US 3,706,313 A
• Filed: 02/04/1971
• Issued: 12/19/1972
• Est. Priority Date: 02/04/1971
• Status: Expired due to Term

• Current Assignee: Dean L. Milani, Richard G. Kerwin
• Original Assignee: Dean L. Milani, Richard G. Kerwin
• Inventors: Milani, Dean L., Kerwin, Richard G.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/112,587
• Time in Patent Office: 684 Days
• Field of Search: 128/419D,421 320/1
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3904 External heart defibrillators [EHD]
• CPC Class Codes: A61N 1/3906 characterised by the form of the shockwave
• CPC Class Codes: A61N 1/3912 Output circuitry therefor, e.g. switches

Abstract

A trapezoidal waveshape, which is known to be the best waveshape for defibrillating the heart, is produced by charging a capacitor, and by starting to discharge it through a silicon controlled rectifier to the load, namely, the body of the patient. Subsequently, a second SCR is used to short circuit the first SCR and load circuit to effect termination of the trapezoidal waveshape rapidly, i.e., effectively dumping the remainder of the charge.

Claims

1. Electric circuit means for discharging a substantially trapezoidal waveshape, comprising output means adapted to be connected to a resistive load such as a human body having a heart to be defibrillated, electrical energy storage means and a discharge circuit in series with said energy storage means and said output means, said discharge circuit comprising a resistor and a first controlled electronic gate substantially in parallel with said energy storage means and said output means, a shunting second controlled electronic gate, means for turning on said first controlled electronic gate to start discharge of electrical energy to said output means, and means for thereafter starting conduction of said second gate to short circuit said first gate and output means.

2. Circuit means as set forth in claim 1, wherein each of said gates comprises a unidirectionally conductive gate.

3. Circuit means as set forth in claim 2, wherein each of said gates comprises a controlled rectifier.

4. Circuit means as set forth in claim 1, wherein said electrical energy storage means comprises a capacitor.

5. Circuit means as set forth in claim 1, wherein the means for starting conduction of said second gate includes means connected across said resistor sensitive to the voltage thereacross and further connected to said second gate to effect conduction thereof in accordance with the voltage developed across said resistor.

6. Circuit means as set forth in claim 5, wherein the means connected across said resistor comprises a series combination of a second resistor and a capacitor, said circuit means further including a transformer having the primary connected across said capacitor and the secondary connected to said second electronic gate to start firing thereof.

7. Circuit means as set forth in claim 6, wherein each of said gates comprises a unidirectionally conductive gate.

8. Circuit means as set forth in claim 7, wherein each of said gates comprises a controlled rectifier.

9. Circuit means as set forth in claim 8, wherein the electrical energy storage means comprises a capacitor.

10. Electric circuit means for discharging a substantially trapezoidal waveshape, comprising output means adapted to be connected to a resistive load such as a human body having a heart to be defibrillated, electrical energy storage means and a discharge circuit in series with said energy storage means and said output means, said discharge circuit comprising a resistor and a first electric switch means substantially in parallel with said energy storage means and said output means, a shunting second electric switch means, means for first rendering said first switch means conductive to start discharge of electrical energy to said output means, and means for thereafter starting conduction of said second electric switch means to short circuit said first gate and output means.