| Autor: |
M J, Niebauer, C F, Babbs, L A, Geddes, J E, Carter, J D, Bourland |
| Rok vydání: |
1984 |
| Předmět: |
|
| Zdroj: |
Japanese heart journal. 25(5) |
| ISSN: |
0021-4868 |
| Popis: |
The overdose shock strengths required to depress ventricular contraction were determined for damped sinusoidal current in 7 metabolically supported, isolated contracting canine hearts. Each heart was suspended in an isoresistive and isotonic solution-through which the defibrillating shocks were delivered. Defibrillation thresholds were determined with standard damped sine wave shocks of 4.4-5.5 msec duration. Then overdose shocks were delivered and the depressant effect on systolic left ventricular pressure was measured for shocks of 3-12 times threshold current. The minimum (threshold) current and energy densities required to defibrillate were 59.5 +/- 4.6 mA/cm2 (average) and 3.12 +/- 0.2 mJ/cm3. Increasing the shock strength above threshold produced a concomitant reduction of postshock left ventricular systolic pressure. The current and energy densities required to produce 50% depression (TD50) of left ventricular systolic pressure were 5.0 and 24.1 times the threshold current and energy densities respectively, indicating a wide safety margin using this criterion. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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