الفهرس 
Cardiovascular PhysiologyOnly 14 pages are availabe for public view
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Abstract
C
IED were first introduced in 1958, then (ICDs) followed in 1980. Since then, more than 2000 models of PMs. There has been a significant change not only in pulse generators and leads but also in the indications for pacing, pacing modalities, implantation techniques and follow up of patients with implanted pacing devices (CIED) include the PM, ICD, CRT and CCM.
Indications of permanent PMs include: sick sinus syndrome, Second and third degree AV block, LBBB, RBBB, congenital long Q-T syndrome, cardiomyopathy and decompensated HF.
Automatic implantable cardioverter-defibrillators are devices resembling PMs and have the ability to treat dangerously tachydysrrhythmias of the heart, either via pacing or defibrillation. Many of these devices can also treat bradydysrrhythmias the same way as PM.
CRT improves symptoms, quality of life (QoL), exercise tolerance, and reduces hospitalizations in patients with advanced HF and prolonged electrical activation (i.e. increased QRS duration).
CCM signals are non-excitatory signals delivered to the LV 30 ms after QRS onset so enhances the strength of LV contraction. CCM effects are independent of QRS duration and additive to those of CRT so decreases LV volumes and increases EF. CCM signals acutely affect calcium handling but also expression of proteins and genes involved in Ca handling so improves exercise tolerance and quality of life.
I. Preoperative Evaluation:
1. Routine preoperative evaluation: CAD (50%) HTN (20%) & DM (10%) Assess: (1) severity (2) current functional status (3) medication. CXR (continuity of leads) • ECG (Spike) • Bioch (K+)
2. Confirm whether a patient has a PM:Interview, medical records, ECG, CXR.
3. Define the type of PM: ID Card and X ray code.
4. Determine patient dependency on PM pacing.
5. Evaluation of PM function and indication for the PM.
II.Intraoperative Management:
Monitor PM Function: ECG and monitor peripheral pulse.
2. Anesthetic Technique: Should be dictated by patient’s underlying physiology &/or procedure.
3. EMI–Induced PM Potential Dysfunction:
A. Electrocautery: unipolar, bipolar and ultrasonic (harmonic).
B. Nature of Procedure:
Lithotripsy (ESWL): Avoid beam focusing near the generator.
Radiology:
Plain X-ray & CT do not affect pacemaker function.
MRI contraindicated generally.
Radio-therapy: Safe (Surgically relocate PM outside radiation field).
ECT itself safe (little current flows within the heart).
III. Emergency Defibrillation or Cardioversion:
Follow existing ACLS guidelines (energy level & paddle placement). Minimize the current flow through the generator & lead system by positioning the paddles:
1. As far as possible from the pulse generator.
2. Perpendicular to the major axis of the generator & leads to the extent possible by placing them in an ‘anterior–posterior’ location.
V. Postoperative Management:
ICU Setup (Continuous ECG monitor, backup pacing & defibrillation). Assure that all PM settings are restored: Interrogate PM (cardiologist/manufacturer).