|
| 1 | +{ |
| 2 | + "cells": [ |
| 3 | + { |
| 4 | + "cell_type": "markdown", |
| 5 | + "metadata": {}, |
| 6 | + "source": [ |
| 7 | + "# Baroreflex Sensitivity Testing\n", |
| 8 | + "\n", |
| 9 | + "**Clinical Application:** Assessment of autonomic function and cardiovascular regulation\n", |
| 10 | + "\n", |
| 11 | + "**Learning Objectives:**\n", |
| 12 | + "1. Understand baroreflex physiology and clinical significance\n", |
| 13 | + "2. Simulate baroreceptor firing dynamics\n", |
| 14 | + "3. Compute baroreflex sensitivity (BRS)\n", |
| 15 | + "4. Interpret results in clinical contexts\n", |
| 16 | + "\n", |
| 17 | + "**Clinical Relevance:**\n", |
| 18 | + "- Post-MI risk stratification (La Rovere et al. 1998)\n", |
| 19 | + "- Heart failure prognosis\n", |
| 20 | + "- Autonomic neuropathy assessment\n", |
| 21 | + "- Syncope evaluation" |
| 22 | + ] |
| 23 | + }, |
| 24 | + { |
| 25 | + "cell_type": "code", |
| 26 | + "execution_count": null, |
| 27 | + "metadata": {}, |
| 28 | + "outputs": [], |
| 29 | + "source": [ |
| 30 | + "import sys\n", |
| 31 | + "sys.path.append('..')\n", |
| 32 | + "import numpy as np\n", |
| 33 | + "import matplotlib.pyplot as plt\n", |
| 34 | + "from src.autonomic.baroreflex import Baroreceptor, BaroreflexController, compute_baroreflex_sensitivity\n", |
| 35 | + "from src.validation.benchmarks import PhysiologicalBenchmarks\n", |
| 36 | + "\n", |
| 37 | + "%matplotlib inline\n", |
| 38 | + "plt.rcParams['figure.figsize'] = (14, 10)\n", |
| 39 | + "print(\"✓ Imports successful\")" |
| 40 | + ] |
| 41 | + }, |
| 42 | + { |
| 43 | + "cell_type": "markdown", |
| 44 | + "metadata": {}, |
| 45 | + "source": [ |
| 46 | + "## Part 1: Baroreceptor Firing Dynamics\n", |
| 47 | + "\n", |
| 48 | + "### Physiological Background\n", |
| 49 | + "\n", |
| 50 | + "Baroreceptors in carotid sinus and aortic arch sense arterial pressure changes:\n", |
| 51 | + "- **High pressure** → Increased firing → ↑ Vagal, ↓ Sympathetic → ↓ HR, ↓ BP\n", |
| 52 | + "- **Low pressure** → Decreased firing → ↓ Vagal, ↑ Sympathetic → ↑ HR, ↑ BP" |
| 53 | + ] |
| 54 | + }, |
| 55 | + { |
| 56 | + "cell_type": "code", |
| 57 | + "execution_count": null, |
| 58 | + "metadata": {}, |
| 59 | + "outputs": [], |
| 60 | + "source": [ |
| 61 | + "# Create baroreceptor model\n", |
| 62 | + "baroreceptor = Baroreceptor()\n", |
| 63 | + "\n", |
| 64 | + "# Test across pressure range\n", |
| 65 | + "pressures = np.linspace(60, 180, 100)\n", |
| 66 | + "firing_rates = [baroreceptor.compute_firing_rate(p, 0.001) for p in pressures]\n", |
| 67 | + "\n", |
| 68 | + "# Plot pressure-firing relationship\n", |
| 69 | + "fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(14, 5))\n", |
| 70 | + "\n", |
| 71 | + "ax1.plot(pressures, firing_rates, 'b-', linewidth=2.5)\n", |
| 72 | + "ax1.axvline(93, color='g', linestyle='--', label='Normal MAP', alpha=0.7)\n", |
| 73 | + "ax1.axvline(100, color='r', linestyle='--', label='Sigmoid midpoint', alpha=0.7)\n", |
| 74 | + "ax1.set_xlabel('Mean Arterial Pressure (mmHg)', fontsize=12, fontweight='bold')\n", |
| 75 | + "ax1.set_ylabel('Firing Rate (spikes/s)', fontsize=12, fontweight='bold')\n", |
| 76 | + "ax1.set_title('Baroreceptor Pressure-Firing Relationship\\n(Chapleau & Abboud 2001)', fontsize=13, fontweight='bold')\n", |
| 77 | + "ax1.legend(fontsize=11)\n", |
| 78 | + "ax1.grid(True, alpha=0.3)\n", |
| 79 | + "\n", |
| 80 | + "# Derivative (sensitivity)\n", |
| 81 | + "dp = np.diff(pressures)\n", |
| 82 | + "dfr = np.diff(firing_rates)\n", |
| 83 | + "sensitivity = dfr / dp\n", |
| 84 | + "ax2.plot(pressures[:-1], sensitivity, 'r-', linewidth=2)\n", |
| 85 | + "ax2.set_xlabel('Pressure (mmHg)', fontsize=12, fontweight='bold')\n", |
| 86 | + "ax2.set_ylabel('Sensitivity (spikes/s/mmHg)', fontsize=12, fontweight='bold')\n", |
| 87 | + "ax2.set_title('Baroreceptor Sensitivity', fontsize=13, fontweight='bold')\n", |
| 88 | + "ax2.grid(True, alpha=0.3)\n", |
| 89 | + "\n", |
| 90 | + "plt.tight_layout()\n", |
| 91 | + "plt.show()\n", |
| 92 | + "\n", |
| 93 | + "print(f\"Firing at 80 mmHg: {baroreceptor.compute_firing_rate(80, 0.001):.1f} spikes/s\")\n", |
| 94 | + "print(f\"Firing at 100 mmHg: {baroreceptor.compute_firing_rate(100, 0.001):.1f} spikes/s\")\n", |
| 95 | + "print(f\"Firing at 120 mmHg: {baroreceptor.compute_firing_rate(120, 0.001):.1f} spikes/s\")" |
| 96 | + ] |
| 97 | + }, |
| 98 | + { |
| 99 | + "cell_type": "markdown", |
| 100 | + "metadata": {}, |
| 101 | + "source": [ |
| 102 | + "## Part 2: Baroreflex Control Loop\n", |
| 103 | + "\n", |
| 104 | + "Simulate complete baroreflex arc: Pressure → Baroreceptor → NTS → Autonomic output" |
| 105 | + ] |
| 106 | + }, |
| 107 | + { |
| 108 | + "cell_type": "code", |
| 109 | + "execution_count": null, |
| 110 | + "metadata": {}, |
| 111 | + "outputs": [], |
| 112 | + "source": [ |
| 113 | + "controller = BaroreflexController()\n", |
| 114 | + "\n", |
| 115 | + "# Simulate pressure ramp\n", |
| 116 | + "times = np.arange(0, 20, 0.01)\n", |
| 117 | + "pressures = 93 + 30 * np.sin(2 * np.pi * times / 10)\n", |
| 118 | + "\n", |
| 119 | + "vagal_outputs = []\n", |
| 120 | + "sympathetic_outputs = []\n", |
| 121 | + "heart_rates = []\n", |
| 122 | + "\n", |
| 123 | + "for t, p in zip(times, pressures):\n", |
| 124 | + " v, s = controller.compute_autonomic_output(p, 0.01, t)\n", |
| 125 | + " hr = controller.compute_heart_rate_response(p, baseline_hr=105, dt=0.01, t=t)\n", |
| 126 | + " vagal_outputs.append(v)\n", |
| 127 | + " sympathetic_outputs.append(s)\n", |
| 128 | + " heart_rates.append(hr)\n", |
| 129 | + "\n", |
| 130 | + "fig, axes = plt.subplots(4, 1, figsize=(14, 12), sharex=True)\n", |
| 131 | + "\n", |
| 132 | + "axes[0].plot(times, pressures, 'b-', linewidth=2)\n", |
| 133 | + "axes[0].set_ylabel('Pressure\\n(mmHg)', fontsize=11, fontweight='bold')\n", |
| 134 | + "axes[0].set_title('Baroreflex Response to Pressure Changes', fontsize=13, fontweight='bold')\n", |
| 135 | + "axes[0].grid(True, alpha=0.3)\n", |
| 136 | + "\n", |
| 137 | + "axes[1].plot(times, vagal_outputs, 'g-', linewidth=2, label='Vagal')\n", |
| 138 | + "axes[1].plot(times, sympathetic_outputs, 'r-', linewidth=2, label='Sympathetic')\n", |
| 139 | + "axes[1].set_ylabel('Autonomic\\nOutput', fontsize=11, fontweight='bold')\n", |
| 140 | + "axes[1].legend(fontsize=10)\n", |
| 141 | + "axes[1].grid(True, alpha=0.3)\n", |
| 142 | + "\n", |
| 143 | + "axes[2].plot(times, heart_rates, 'purple', linewidth=2)\n", |
| 144 | + "axes[2].set_ylabel('Heart Rate\\n(bpm)', fontsize=11, fontweight='bold')\n", |
| 145 | + "axes[2].grid(True, alpha=0.3)\n", |
| 146 | + "\n", |
| 147 | + "# Phase relationship\n", |
| 148 | + "axes[3].scatter(pressures, heart_rates, c=times, cmap='viridis', s=10, alpha=0.6)\n", |
| 149 | + "axes[3].set_xlabel('Pressure (mmHg)', fontsize=11, fontweight='bold')\n", |
| 150 | + "axes[3].set_ylabel('Heart Rate (bpm)', fontsize=11, fontweight='bold')\n", |
| 151 | + "axes[3].set_title('Pressure-HR Relationship', fontsize=12, fontweight='bold')\n", |
| 152 | + "axes[3].grid(True, alpha=0.3)\n", |
| 153 | + "\n", |
| 154 | + "plt.tight_layout()\n", |
| 155 | + "plt.show()\n", |
| 156 | + "\n", |
| 157 | + "print(\"✓ Baroreflex demonstrates reciprocal autonomic control\")" |
| 158 | + ] |
| 159 | + }, |
| 160 | + { |
| 161 | + "cell_type": "markdown", |
| 162 | + "metadata": {}, |
| 163 | + "source": [ |
| 164 | + "## Part 3: Clinical Baroreflex Sensitivity Testing\n", |
| 165 | + "\n", |
| 166 | + "### Sequence Method (La Rovere et al. 1998)\n", |
| 167 | + "\n", |
| 168 | + "Identify sequences where systolic BP and RR interval change in same direction" |
| 169 | + ] |
| 170 | + }, |
| 171 | + { |
| 172 | + "cell_type": "code", |
| 173 | + "execution_count": null, |
| 174 | + "metadata": {}, |
| 175 | + "outputs": [], |
| 176 | + "source": [ |
| 177 | + "# Simulate spontaneous BP variations\n", |
| 178 | + "np.random.seed(42)\n", |
| 179 | + "n_beats = 100\n", |
| 180 | + "baseline_sbp = 120\n", |
| 181 | + "baseline_rr = 850 # ms\n", |
| 182 | + "\n", |
| 183 | + "sbp_variations = baseline_sbp + np.random.randn(n_beats) * 5\n", |
| 184 | + "rr_variations = baseline_rr + (sbp_variations - baseline_sbp) * 10 + np.random.randn(n_beats) * 5\n", |
| 185 | + "\n", |
| 186 | + "# Compute BRS\n", |
| 187 | + "brs_values = []\n", |
| 188 | + "for i in range(len(sbp_variations) - 3):\n", |
| 189 | + " dp = sbp_variations[i+3] - sbp_variations[i]\n", |
| 190 | + " drr = rr_variations[i+3] - rr_variations[i]\n", |
| 191 | + " if abs(dp) > 1:\n", |
| 192 | + " brs = drr / dp\n", |
| 193 | + " if 3 < brs < 30:\n", |
| 194 | + " brs_values.append(brs)\n", |
| 195 | + "\n", |
| 196 | + "mean_brs = np.mean(brs_values) if brs_values else 0\n", |
| 197 | + "\n", |
| 198 | + "fig, axes = plt.subplots(2, 2, figsize=(14, 10))\n", |
| 199 | + "\n", |
| 200 | + "# Time series\n", |
| 201 | + "axes[0,0].plot(sbp_variations, 'b-', linewidth=1.5)\n", |
| 202 | + "axes[0,0].set_ylabel('SBP (mmHg)', fontsize=11, fontweight='bold')\n", |
| 203 | + "axes[0,0].set_title('Systolic Blood Pressure', fontsize=12, fontweight='bold')\n", |
| 204 | + "axes[0,0].grid(True, alpha=0.3)\n", |
| 205 | + "\n", |
| 206 | + "axes[0,1].plot(rr_variations, 'r-', linewidth=1.5)\n", |
| 207 | + "axes[0,1].set_ylabel('RR Interval (ms)', fontsize=11, fontweight='bold')\n", |
| 208 | + "axes[0,1].set_title('RR Intervals', fontsize=12, fontweight='bold')\n", |
| 209 | + "axes[0,1].grid(True, alpha=0.3)\n", |
| 210 | + "\n", |
| 211 | + "# Scatter plot\n", |
| 212 | + "axes[1,0].scatter(sbp_variations, rr_variations, alpha=0.6, s=50)\n", |
| 213 | + "z = np.polyfit(sbp_variations, rr_variations, 1)\n", |
| 214 | + "p = np.poly1d(z)\n", |
| 215 | + "axes[1,0].plot(sbp_variations, p(sbp_variations), 'r--', linewidth=2, label=f'BRS = {z[0]:.1f} ms/mmHg')\n", |
| 216 | + "axes[1,0].set_xlabel('SBP (mmHg)', fontsize=11, fontweight='bold')\n", |
| 217 | + "axes[1,0].set_ylabel('RR Interval (ms)', fontsize=11, fontweight='bold')\n", |
| 218 | + "axes[1,0].set_title('Baroreflex Sensitivity', fontsize=12, fontweight='bold')\n", |
| 219 | + "axes[1,0].legend(fontsize=11)\n", |
| 220 | + "axes[1,0].grid(True, alpha=0.3)\n", |
| 221 | + "\n", |
| 222 | + "# BRS distribution\n", |
| 223 | + "axes[1,1].hist(brs_values, bins=20, edgecolor='black', alpha=0.7)\n", |
| 224 | + "axes[1,1].axvline(mean_brs, color='r', linestyle='--', linewidth=2, label=f'Mean = {mean_brs:.1f}')\n", |
| 225 | + "axes[1,1].axvspan(3, 30, alpha=0.2, color='green', label='Normal range')\n", |
| 226 | + "axes[1,1].set_xlabel('BRS (ms/mmHg)', fontsize=11, fontweight='bold')\n", |
| 227 | + "axes[1,1].set_ylabel('Frequency', fontsize=11, fontweight='bold')\n", |
| 228 | + "axes[1,1].set_title('BRS Distribution', fontsize=12, fontweight='bold')\n", |
| 229 | + "axes[1,1].legend(fontsize=10)\n", |
| 230 | + "axes[1,1].grid(True, alpha=0.3, axis='y')\n", |
| 231 | + "\n", |
| 232 | + "plt.tight_layout()\n", |
| 233 | + "plt.show()\n", |
| 234 | + "\n", |
| 235 | + "benchmarks = PhysiologicalBenchmarks()\n", |
| 236 | + "print(f\"\\nBaroreflex Sensitivity: {mean_brs:.1f} ms/mmHg\")\n", |
| 237 | + "print(f\"Normal range: {benchmarks.baroreflex.brs_normal.min_value:.1f}-{benchmarks.baroreflex.brs_normal.max_value:.1f} ms/mmHg\")\n", |
| 238 | + "print(f\"Interpretation: {'Normal' if 3 < mean_brs < 30 else 'Impaired'}\")" |
| 239 | + ] |
| 240 | + }, |
| 241 | + { |
| 242 | + "cell_type": "markdown", |
| 243 | + "metadata": {}, |
| 244 | + "source": [ |
| 245 | + "## Summary\n", |
| 246 | + "\n", |
| 247 | + "### Clinical Interpretation\n", |
| 248 | + "\n", |
| 249 | + "**BRS Values:**\n", |
| 250 | + "- **>12 ms/mmHg**: Normal baroreflex function\n", |
| 251 | + "- **6-12 ms/mmHg**: Moderately impaired\n", |
| 252 | + "- **<6 ms/mmHg**: Severely impaired (high risk)\n", |
| 253 | + "\n", |
| 254 | + "**Clinical Applications:**\n", |
| 255 | + "1. Post-MI risk stratification\n", |
| 256 | + "2. Heart failure prognosis \n", |
| 257 | + "3. Autonomic neuropathy detection\n", |
| 258 | + "4. Drug effect assessment\n", |
| 259 | + "\n", |
| 260 | + "---\n", |
| 261 | + "© 2025 Multi-Heart-Model Project | MIT License" |
| 262 | + ] |
| 263 | + } |
| 264 | + ], |
| 265 | + "metadata": { |
| 266 | + "kernelspec": { |
| 267 | + "display_name": "Python 3", |
| 268 | + "language": "python", |
| 269 | + "name": "python3" |
| 270 | + } |
| 271 | + }, |
| 272 | + "nbformat": 4, |
| 273 | + "nbformat_minor": 4 |
| 274 | +} |
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