Key result
Direct blunt cardiac trauma in dogs caused 50% immediate mortality from arrhythmias, with survivors showing transient or sustained LV dysfunction depending on impact severity.
Why the study?
Does blunt cardiac trauma impair left ventricular function in an open-chest dog model?
Does blunt cardiac trauma impair left ventricular function in an open-chest dog model?
Blunt cardiac trauma causes severity-dependent impairment of left ventricular function and structural contusion, with survivors of initial arrhythmias showing moderate, survivable functional impairment.
Answers are grounded in this paper and cite their sources.
Animal model findings on blunt cardiac trauma should not guide human care; leaves open need for clinical studies on severity-dependent LV dysfunction.
The purpose of this investigation was to study the acute effects of blunt cardiac trauma upon left ventricular (LV) function. In 34 open-chest anesthetized dogs, direct impact to the anterior surface of the heart was produced by an air-pressurized impactor at 12 m/sec in 15 dogs and at 18 m/sec in 19 dogs. Impact displacement was limited to 2 cm. Seventeen dogs (50%) died of arrhythmias within a few minutes of impact. In nine surviving dogs impacted at 12 m/sec, there was an immediate reduction of LV function following impact. At 5 minutes following impact this reduction of LV function was characterized by a 19% reduction of cardiac output, 35% reduction of maximal isovolumic LV rate of change of pressure (dp/dt), a 12% reduction of peak aortic flow, and a 23% reduction of peak rate of change of flow. These indices of ventricular performance returned nearly to control levels 60 to 90 minutes following impact. In eight surviving dogs that experienced impact at 18 m/sec, impairment of LV function was greater in the immediate impact period following impact and impaired function remained throughout the 90-minute duration of observation. Autopsy of all dogs showed cardiac contusion. Following the more severe impact, contusions were more extensive and involved the left ventricular endocardial surface and intraventricular septum as well as the epicardial surface. Parallel changes, therefore, of the extent of pathologic changes and the extent of functional impairment were observed. Animals that survived the potentially fatal arrhythmias immediately after impact showed functional impairment of the heart that was only moderate and compatible with life.
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Stein et al. (1982) studied Blunt cardiac trauma (n=34). Direct impact to the anterior surface of the heart vs. Pre-impact control levels was evaluated on Left ventricular (LV) function. Direct blunt cardiac trauma in dogs caused 50% immediate mortality from arrhythmias, with survivors showing transient or sustained LV dysfunction depending on impact severity.
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