VI] Sensorized Cardiac Pacemaker Flashcards
What are coronaries and what is their role ?
Coronaries are arteries of the heart. They ensure the blood supply of the heart.
To what could lead the coronaries occlusion ?
Heart attack/infarct and necrosis of heart muscle.
Who’s the “pacemaker” in the heart.
The sinoartrial node
Describe the structure/pathway responsible for heart pulses.
1 - Sinoartrial node 2 - Internodal pathway 3 - Atrioventricular node 4- Artrioventricular bundle (Bundle of HIS) 5- Bundle branches 6- Purkinje fibers
What leads to slow spontaneous depolarization of the heart cells ?
Leakage currents.
What determines the firing frequency of the heart ?
Slope of depolarization, threshold and maximum
diastolic voltage.
What is the aim of an electrocardiogram ?
Recording the ELECTRICAL activity of the heart.
Defines the different events of electrical recording of the heart (cf: electrical activity of the heart).
Atrial depolarization - QRS complex - Ventricular depolarization - Ventricular repolarization
Describe the heart cycle (filling of ventricles and blabla)
Ventricular filling + Atrial contraction (=Ventricular filling, mid to late diastole)
Isovolumetric relaxation + ventricular filling (=ventricular systole , atria in diastole)
Isovolumetric relaxation and ventricular filling (early diastole)
Cite the principle and two functionality of cardiac pacemakers
Artificial depolarization of heart muscle cells
Functionalities : sensing of residual functionality and pacing on demand
Site pacemakers components
Stimulator and battery - electrodes - cables with plugs
Site 5 types of pacemakers
Chamber paced Chamber sensed Response sensing Programmability rate modulation Antiarrhythmia function
What are the goal of sensors in pacemakers
Adapt to physical and mental load that disturb body state
Cite the three types on control mechanism in the heart
Chronotropic
Inotropic
Dromotropic
What is the chronotropic control mechanism
The control of the frequency - it is an open loop control
What is the inotropic control mechanisms ?
The strength of the contraction - closed loop control
What is the dromotropic control mechanisms ?
Conduction velocity over AV node
Closed loop control
Which Input variable could be taken into account for sensors ?
Partial pressures of oxygen or carbon dioxide
Saturation of oxygen
Tidal volume
Stroke volume
Which parameters could be taken into account for frequency adaptative pacemakers
Activity (vibrations/acceleration sensors)
Breathing volume
Blood temperature
What would be the function of frequency pacemakers
Adaptâtes of heart frequency under load if Sinoartrial node does not correctly adapt
What other input variables could be important for adaptive pacemakers beyond chronotropic incompetence ?
AV conduction Time (dromotropic control, elegant approach)
QT interval of intracardial ECG
Contractibility of myocard (dp/dt)
(Inotropic control, curvature of optic fiber, acceleration of myocard)
What is the limit of chronotropic pacemaker ?
No information about hemodynamics needs
No adaptation to mental load or fever
Artefact suppression needed…
Which measurement is crucial for inotropic pacemaker ?
Measurement of myocardial acceleration (dp/dt)
PEA: peak endocardial acceleration
