Influence of the elevation of the left ventricular diastolic pressure on the values of the first temporal derivative of the ventricular pressure (dP/dt)

PURPOSE: To assess the effects of the elevation of the left-ventricular end-diastolic pressure (LVEDP) on the value of the 1st temporal derivative of the ventricular pressure (dP/dt). METHODS: Nineteen anesthetized dogs were studied. The dogs were mechanically ventilated and underwent thoracotomy with parasympathetic nervous system block. The LVEDP was controlled with the use of a perfusion circuit connected to the left atrium and adjusted to the height of a reservoir. The elevation of the LVEDP was achieved by a sudden increase in the height of a reservoir filled with blood. Continuous recordings of the electrocardiogram, the aortic and ventricular pressures and the dP/dt were performed. RESULTS: Elevation of the LVEDP did not result in any variation of the heart rate (167 +/- 16.0 bpm, before the procedure; 167 +/- 15.5 bpm, after the procedure). All the other variables assessed, including systolic blood pressure (128 +/- 18.3 mmHg and 150 +/- 21.5 mmHg), diastolic blood pressure (98 +/- 16.9 mmHg and 115 +/- 19.8 mmHg), LVEDP (5.5 +/- 2.49 and 9.3 +/- 3.60 mmHg), and dP/dt (4,855 +/- 1,082 mmHg/s and 5,149 +/- 1,242 mmHg/s) showed significant increases following the expansion of the ventricular cavity. Although the elevation of the dP/dt was statistically significant, 6 dogs curiously showed a decrease in the values of dP/dt. CONCLUSION: Sudden elevation of the LVEDP resulted in increased values of dP/dt; however, in some dogs, this response was not uniform.