Clinical Implantable Cardiac Pacemaker Pulse Generator
Provides programmable constant-voltage pacing pulses with telemetry programming head.
Biomedical Engineering / Pacemaker Strength-Duration
FREE TO EXPLORELABORATORY 39 · BIOMEDICAL ENGINEERING
Implantable Cardiac Pacemaker Lapicque Strength-Duration & Chronaxie Curve
Determine the chronaxie time t_ch and rheobase voltage V_rh of an implantable cardiac pacemaker lead-tissue interface across pulse widths using the Lapicque-Weiss model. Explore interactive physiological instrumentation simulation, biomechanics, and biomedical engineering telemetry.
BIOINSTRUMENTATION · BIOSIGNALS · BIOMECHANICS · IMAGING
Your virtual biomedical engineering laboratory.
PACING CAPTURE THRESHOLD VOLTAGE V_TH—
PHYSIOLOGICAL & TEST CELL TELEMETRY
Ready to sample with Pulse Width t_p = 0.5 ms.
Adjust Pulse Width t_p, then execute biomedical trial.
Biomedical engineering telemetry and physiological states are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity biological and physiological modeling.
Biomedical assumptions and boundary condition limits
The Lapicque-Weiss model assumes a simple parallel R-C membrane circuit, neglecting active voltage-gated sodium channel reactivation dynamics. Evaluated on a Medtronic clinical cardiac pulse generator interfaced with a steroid-eluting active-fixation bipolar endocardial pacing lead (tip area 1.2 mm², pacing impedance R = 550 Ω) immersed in 37.0 °C physiological saline. Rheobase voltage V_rh = 0.6500 V, chronaxie time t_ch = 0.4923 ms, yielding Lapicque slope m_ch = 0.3200 V·ms across pulse widths t_p from 0.20 to 1.00 ms (1/t_p from 5.0 to 1.0 ms⁻¹).
Biomedical apparatus & physiological sensors.
Steroid-Eluting Bipolar Endocardial Pacing Lead (1.2 mm² tip)
Provides platinized titanium pacing electrode with dexamethasone sodium phosphate elution.
Cardiac Tissue Impedance & Evoked Response Simulator
Simulates 550 Ω tissue impedance and generates evoked R-wave action potential upon capture.
High-Speed Isolated Digital Storage Oscilloscope (100 MS/s)
Measures delivered voltage pulse amplitudes and duration with sub-microsecond accuracy.
Pacemaker RF Telemetry Programming Wand
Adjusts pulse duration t_p and executes automated threshold search algorithms via wireless RF telemetry.
Thermostatically Controlled Saline Tissue Bath (37.0 °C)
Maintains physiological temperature and electrolyte conductance matching human blood.
FOLLOW THE METHOD
A reason behind every step.
Determine the chronaxie time t_ch and rheobase voltage V_rh of an implantable cardiac pacemaker lead-tissue interface across pulse widths using the Lapicque-Weiss model. Standardized parameter settings: 0.2, 0.25, 0.3333, 0.5, 0.6667, 1.0 ms.
01
Pacing Lead Bath Mounting and Impedance Verification
Submerge bipolar pacing lead tip in 37.0 °C saline, connect to pacing simulator, and verify pacing impedance R = 550 ± 20 Ω via telemetry.
02
Telemetry Programmer Interrogation
Position wireless programming wand over pacemaker, establish bidirectional telemetry link, and select automated capture threshold testing mode.
03
Initial Pulse Width Configuration
Program pacemaker pulse duration to t_p = 0.20 ms (inverse width 1/t_p = 5.00 ms⁻¹).
04
Capture Threshold Voltage Search
Step pacing voltage downward from 3.0 V in 0.05 V increments until evoked electrical response ceases, recording last successful capture voltage as V_th.
05
Pulse Width Progression Sequence
Increment pulse width through 0.25 ms (1/t_p = 4.00), 0.333 ms (3.00), 0.50 ms (2.00), 0.667 ms (1.50), and 1.00 ms (1.00 ms⁻¹), measuring capture threshold V_th at each setting.
06
Lapicque-Weiss Linear Regression Analysis
Plot threshold voltage V_th versus inverse pulse width 1/t_p, extract slope m_ch and y-intercept V_rh, and calculate chronaxie time t_ch = m_ch / V_rh.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into biomedical engineering insight.
Points are your recorded observations. The solid regression line validates Pacemaker Strength-Duration mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
V_th = m_ch · (1/t_p) + V_rh = 0.3200 · (1/t_p) + 0.6500
| # | Pacing Pulse Duration t_p (ms) | Pacing Capture Threshold Voltage V_th (V) | Inverse pulse duration 1/t_p (ms⁻¹) | Threshold voltage V_th (V) | Remove |
|---|
No readings yet. Execute a biomedical trial and record it.
Calculate it yourself.
CHECK YOUR UNDERSTANDING