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An isolated, blood-perfused, feline heart preparation for evaluating pharmacological interventions during myocardial
Insights
This study presents a feline heart model to assess myocardial ischemic injury. The model effectively evaluates changes in ventricular function and myocardial composition following ischemia and reperfusion.
Area of Science:
- Cardiovascular Physiology
- Ischemic Heart Disease Research
Background:
- Assessing myocardial ischemic injury requires reliable experimental models.
- Isolated heart preparations offer controlled environments for studying cardiac function.
Purpose of the Study:
- To describe and validate a feline isolated heart model for evaluating myocardial ischemic injury.
- To assess the impact of normothermic global ischemia and reperfusion on cardiac function and myocardial composition.
Main Methods:
- Feline hearts were perfused with oxygenated arterial blood.
- Left ventricular function was assessed using a fluid-filled balloon.
- Hearts underwent varying durations of normothermic global ischemia followed by reperfusion.
- Myocardial tissue composition (water, electrolytes, enzymes) was analyzed.
Main Results:
- Isolated hearts maintained stable function for two hours under perfusion.
- 40 minutes of ischemia/reperfusion decreased contractility and increased water/sodium.
- 60 minutes of ischemia/reperfusion impaired both contractility and compliance, with altered electrolyte and enzyme levels.
Conclusions:
- The feline isolated heart model is suitable for studying myocardial ischemic injury.
- The model demonstrates dose-dependent functional and compositional changes following ischemia/reperfusion.
- This preparation can be used to test pharmacological interventions for myocardial protection.
Abstract:
A preparation is described in which feline hearts were perfused with arterial blood drawn from a blood-donor cat. Ventricular function was measured with a fluid-filled latex balloon within the left ventricle. Left ventricular developed pressure, maximum left ventricular dP/dt, ventricular compliance, and coronary blood flow changed only slightly during two hours of perfusion at a constant pressure of 75 mmHg. Water, sodium, potassium, and calcium contents, and creatine kinase activity of isolated hearts did not differ from the values obtained for intact hearts from the blood-donor cats. Isolated hearts subjected to 40 minutes of normothermic global ischemia with one hour of reperfusion exhibited significantly decreased contractility, but no change in ventricular compliance. Myocardial water and sodium contents were increased after 40 minutes of ischemia and reperfusion. Hearts subjected to 60 minutes of ischemia with reperfusion exhibited decreases in both contractility and compliance. A prolonged reactive hyperemic response was maintained throughout the hour of reperfusion. Myocardial sodium content increased more than could be accounted for by edema formation; decreases were observed in potassium content and creatine kinase activity while calcium content was increased. The applicability of this model for evaluating the effects of pharmacological interventions on myocardial ischemic injury are discussed.