Biphasic pulse generator for an implantable defibrillator

• US 4,850,357 A
• Filed: 01/12/1988
• Issued: 07/25/1989
• Est. Priority Date: 01/12/1988
• Status: Expired due to Fees

• Current Assignee: Mieczyslaw Mirowski
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Bach, Stanley M. Jr.
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/143,061
• Time in Patent Office: 560 Days
• Field of Search: 128/419 D, 128/419 PG, 128/421, 128/696, 307/106
• US Class Current: 607/7
• CPC Class Codes: A61N 1/3937 Monitoring output parameters

Abstract

A circuit for generating a biphasic voltage pulse to restore rhythm to a fibrillating heart, the circuit utilizing a capacitor for providing the voltage pulse. The circuit further comprises first and second thyristors to regulate the voltage and first and second electrodes to apply the regulated voltage to the fibrillating heart. The circuit further comprises an output sensing circuit that senses the exponential decay of the capacitor and signals a control circuit to switch the thyristors such that after one thyristor applies the voltage pulse to the heart in a first polarity, the other thyristor applies the voltage pulse in the opposite polarity. Therefore, substantially all energy in the capacitor is provided to the heart.

Claims

1. A circuit for generating a biphasic pulse to restore rhythm to a fibrillating heart, said circuit comprising:

capacitor means for providing a voltage to restore rhythm to a fibrillating heart;

thyristor means, connected to said capacitor means, for regulating said voltage and providing a regulated voltage;

first electrode means, connected to said thyristor means, for receiving and applying said regulated voltage to said fibrillating heart;

second electrode means, connected to said thyristor means, for receiving and applying said regulated voltage to said fibrillating heart;

output sensing means, connected to said thyristor means and one of said electrode means, for sensing an exponential decay of said regulated voltage and providing a sensed signal corresponding to said sensed exponential decay; and

control circuit means, connected to said output sensing means, for controlling said thyristor means for delivering said regulated voltage in a first polarity and subsequently in a second polarity opposite said first polarity to said fibrillating heart via said first and second electrode means.

2. A circuit for generating a biphasic pulse to restore rhythm to a fibrillating heart, said circuit comprising:

capacitor means for providing a voltage to restore rhythm to a fibrillating heart, said capacitor means having first and second terminals;

first and second thyristor means, both connected to said first terminal of said capacitor means, for regulating said voltage and providing a regulated voltage;

first electrode means, connected to said first thyristor means, for receiving and applying said regulated voltage to said fibrillating heart;

second electrode means, connected to said second thyristor means, for receiving and applying said regulated voltage to said fibrillating heart;

output sensing means, connected to said first thyristor means and said first electrode means, for sensing an exponential decay of said regulated voltage and providing a sensed signal corresponding to said sensed exponential decay; and

control circuit means, connected to said output sensing means, for controlling which of said first and second thyristor means is on such that when said first thyristor is on, current flows through said capacitor means for delivering said regulated voltage to the heart in a first polarity via said first and second electrode means, and when said second thyristor is on, current flows through said capacitor means for delivering said regulated voltage to the heart in a second polarity opposite said first polarity via said first and second electrode means, to restore rhythm to said fibrillating heart.

3. The circuit of claim 2, and further comprising:

first and second drive circuits, connected to said control circuit, said first drive circuit for driving said first thyristor means and said second drive circuit for driving said second thyristor means.

4. The circuit of claim 3, and further comprising:

a first electronic switch connected to said first drive circuit, said second electrode means, said first thyristor means, and said second terminal of said capacitor means, for forming a first circuit such that said first circuit delivers said voltage to said fibrillating heart; and

a second electronic switch connected to said second drive circuit, said first electrode means, said second thyristor means, and said second terminal of said capacitor means, for forming a second circuit such that said second circuit delivers said voltage to said fibrillating heart.

5. The circuit of claim 2, and further comprising a capacitor discharge means for discharging said capacitor means, and wherein said capacitor means charges to a high voltage and then discharges to a low voltage.

6. The circuit of claim 2, wherein said first and second thyristor means further comprise first and second high voltage isolation transformer for isolating said first and second thyristor means.