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[Afterload and blood pressure amplitude in dilated cardiomyopathy]
1Universität Jena, Klinik für Innere Medizin III, Jena. uwe.leder@uni-jena.de
Insights
Beat-to-beat variations in diastolic blood pressure affect left ventricular afterload and contractility. This study found reduced interdependence between blood pressure and afterload in dilated cardiomyopathy patients, indicating impaired left ventricular function.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Hemodynamics
Context:
- Beat-to-beat variability in diastolic blood pressure influences left ventricular afterload.
- These variations impact myocardial contractility and blood pressure amplitude.
- Assessing the interdependence between blood pressure and afterload changes is crucial for understanding cardiac function.
Purpose:
- To evaluate the relationship between blood pressure and left ventricular afterload in healthy individuals and patients with dilated cardiomyopathy.
- To quantify the interdependence of blood pressure amplitude and systolic pressure slopes with preceding diastolic pressures and interbeat intervals.
- To determine if this interdependence is diminished in dilated cardiomyopathy, particularly in those with reduced ejection fraction.
Summary:
- Continuous blood pressure recordings were analyzed in 20 healthy volunteers and 20 patients with dilated cardiomyopathy.
- Correlation coefficients were calculated to assess the interdependence between blood pressure parameters and preceding diastolic pressures/interbeat intervals.
- Healthy volunteers showed strong interdependence, while patients with dilated cardiomyopathy, especially those with severely reduced ejection fraction, exhibited significantly lower interdependence, indicating impaired left ventricular contractility.
Impact:
- The findings highlight a significant impairment in left ventricular contractility in patients with dilated cardiomyopathy.
- The study demonstrates that the response of systolic blood pressure amplitude and slope to afterload variations can serve as a metric for assessing left ventricular contractility.
- This research provides a potential non-invasive method for evaluating cardiac function and disease progression in dilated cardiomyopathy.
Abstract:
The beat-to-beat variability of the diastolic blood pressure induces small variations in the afterload of the left ventricle. These variations influence myocardial contractility, and thus blood pressure amplitude. We assessed the interdependence of blood pressure and changes in the afterload. We continuously recorded blood pressure (duration 200 s, at rest) in 20 patients with dilated cardiomyopathy (ejection fraction 32 +/- 13%, left ventricular diameter 67 +/- 8 mm) and in 20 healthy volunteers. Interbeat intervals, diastolic pressures, systolic pressure amplitudes and mean slopes of systolic pressure amplitudes were measured. Correlation coefficients (r) were calculated to assess the interdependence of blood pressure amplitudes/mean systolic slopes and the preceding diastolic pressures/interbeat intervals, respectively. In healthy volunteers we found a strong interdependence between blood pressure amplitude and the preceding diastolic pressures (r = 0.62 +/- 0.21 and 0.47 +/- 0.22). Higher diastolic pressures were followed by higher blood pressure amplitudes, and by steeper slopes of the systolic peaks. In patients with dilated cardiomyopathy, such interdependence was significantly lower (r = 0.33 +/- 22 and r = 0.28 +/- 0.35), and in patients with severely reduced left ventricular function (ejection fraction < 32%) was only marginal (r = 0.23 +/- 0.27 and 0.21 +/- 0.44, respectively). The forces of the isovolumetric contraction necessary to initiate the ejection phase of the left ventricle depend on the afterload, i.e. on the diastolic pressure. The responses of amplitude and slope of the systolic blood pressure to small changes in the afterload make it possible to assess left ventricular contractility. The latter is impaired in dilated cardiomyopathy.