Distinct morphologies of arterial waveforms reveal preload‐, contractility‐, and afterload‐deficient hemodynamic instability: An in silico simulation study

Figures

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  FIGURE 1. Two arterial waveforms with the systolic peak, dicrotic notch, and diastolic end. In the left panel, the division of the arterial waveform in systole and diastole by the dicrotic notch is depicted. The relative dicrotic notch pressure is indicated here. A C‐type anacrotic notch is visible in the left panel, indicated together with the augmented pressure. In the right panel, the division between systolic upstroke and downstroke is shown. Three relative pressures are indicated: pulse pressure, descending pressure, and diastolic upswing pressure

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  FIGURE 2. Arterial waveforms of a simulated 60‐year‐old adult with normal physiology (black), reduced blood volume (blue, −26%), reduced left ventricular contractility (red, −85%) and reduced systemic vascular resistance (yellow, −60%). The examples illustrating the reduced situations were selected based on a mean arterial pressure of around 60 mmHg to facilitate comparison. In the left panel absolute waveforms with detected notches are displayed, showing a reduction in pressure and distinct change in morphology when the three variables are reduced. In the right panel the same waveforms are displayed, but now normalized, ranging from 0 to 1 in pressure. The differences in morphology can be seen more clearly here: reduction of the three variables changes the waveform shape differently

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  FIGURE 3. Arterial waveforms of simulated adults of 20, 40, 60, and 80 years old with reduced blood volume (blue), reduced left ventricular contractility (red) and reduced systemic vascular resistance (yellow). For these scenarios mean arterial pressure was aimed at 60 mmHg to make them comparable, the detected anacrotic and dicrotic notches are marked. The waveform morphologies of the three causes differ the most in the older adults. In the younger adults, the waveforms of the reduced preload and contractility look more alike; with reduced afterload the pulse pressure is clearly higher. For all ages, the dicrotic notch and timing of the systolic peak differ between the three causes

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  FIGURE 4. Arterial waveforms of a simulated 60‐year‐old adult with reduced blood volume (blue), reduced left ventricular contractility (red) and reduced systemic vascular resistance (yellow). The detected anacrotic and dicrotic notches are indicated with markers. In the reduced situations (dashed lines) the aim was to bring MAP to 60 mmHg to make the situations comparable. Baroreflex compensatory mechanisms were added until MAP was 70 mmHg (solid lines). To achieve this HR, LVC, and SVR were increased, and venous compliance decreased. For obvious reasons VC, LVC, and SVR were not changed in the situation of BV, LVC, and SVR reduction respectively. Heart rate influences the morphology of the waveform the most. Abbreviations: HR, heart rate; VC, venous compliance; LVC, left ventricular contractility; SVR, systemic vascular resistance; MAP, mean arterial pressure

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  FIGURE 5. Arterial waveforms of a simulated 60‐year‐old adult (top three subplots) with normal physiology (black), reduced blood volume (blue, steps of 2%), reduced left ventricular contractility (red, steps of 5%) and reduced systemic vascular resistance (yellow, steps of 5%). All waveforms are normalized, ranging from 0 to 1 in both pressure and time. The most variation can be seen in the systolic downstroke and dicrotic notch area. The correlation coefficients (bottom) of the first (purple) and second (green) principal components, show a high correlation at the systolic peak, upstroke, downstroke and dicrotic notch

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  FIGURE 6. Scores of the first two principal components based on arterial waveform features of a 60‐year‐old adult with normal physiology (black), reduced blood volume (blue, steps of 2%), reduced left ventricular contractility (red, steps of 5%), and reduced systemic vascular resistance (yellow, steps of 5%). Based on these principal components a clear distinction can be made between the three scenarios

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  FIGURE 7. Scores of the first two principal components based on the arterial waveform features of four simulated adults: 20, 40, 60, and 80 years old. In each of the cases normal physiology (black) is shown, together with reduced blood volume (blue, steps of 2%), reduced left ventricular contractility (red, steps of 5%), and reduced systemic vascular resistance (yellow, steps of 5%). Within one age a distinction can be made between the three reduction scenarios, but between cases of different ages this is not possible

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  FIGURE A1. Results of wave separation in a 60‐year‐old control subject and with hemodynamic instability based on reduced preload, contractility, and afterload with a mean arterial pressure at 60 mmHg