Ventricular fibrillation thresholds in Langendorff perfused rabbit hearts: all or none effect of low potassium concentration.

Abstract

The median single pulse ventricular fibrillation threshold of 56 determinations in eight isolated rabbit hearts perfused with a Krebs-Henseleit solution was 36 mA, with a range from 12.5 to above 50 mA. The fibrillation threshold remained in the same range when the potassium concentration in the perfusing fluid was decreased from its normal 5.6 mmol.litre-1 to as low as 1.8 mmol.litre-1. A further decrease in potassium concentration reduced the fibrillation threshold to a median value of 1.6 mA in nine determinations on six hearts. With a 1.6 mmol.litre-1 potassium concentration, thresholds were in either the high or the low range depending on the individual heart. A pronounced shortening of refractory period and an earlier vulnerable period were associated with the sharp change in fibrillation threshold; the diastolic extrasystolic threshold, cycle length, and RT interval duration increased in a more linear manner as the potassium concentration was lowered.

• Authors: M MacConaill
• Journal: Cardiovascular research (Cardiovasc Res) Vol. 21 Issue 6 Pg. 463-8 (Jun 1987) ISSN: 0008-6363 [Print] England
• PMID: 3652113 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Potassium

Topics

• Animals
• Heart (physiopathology)
• In Vitro Techniques
• Perfusion
• Potassium (pharmacology)
• Rabbits
• Sensory Thresholds (drug effects, physiology)
• Time Factors
• Ventricular Fibrillation (physiopathology)