Makindo Medical Notes

Students often get confused which chamber comes first in the coding but the paced chamber is the most important as without a paced chamber it's not a pacemaker so it naturally comes first. True pacemaker malfunction is uncommon, pseudo malfunction is much more common

About pacemaker codes

• A pacemaker consists of a pulse generator and pacing leads. Pacemaker leads are usually inserted into the venous system and positioned on the inner surface (endocardium) of the right atrium or ventricle or both. They are attached to the endocardium by a small screw mechanism, or are held in place by tines.
• Pacemaker leads may also be placed on the outside of the heart (epicardium) during a surgical procedure. These leads are either sewn onto the heart, or fixed in place with a small screw-in mechanism.
• A standard dual-chamber pacemaker has a lead in the right atrium and a lead in the right ventricle. (A dual-chamber defibrillator has a pacing lead-in the right atrium and a pacing/defibrillation lead in the right ventricle. The latter delivers the defibrillation shock, as well as pacing
• Biventricular pacing is a newly developed type of pacing incorporating a third lead, which is positioned to activate the posterolateral wall of the left ventricle. This results in "ventricular resynchronization, which can improve ventricular haemodynamics, and relieve heart failure symptoms in certain patients with heart failure and conduction abnormalities.
• Dual chamber pacemakers can be programmed to sense activity in one chamber (usually the atrium) and deliver a pacing stimulus in the other chamber (usually the ventricle) after a certain time delay. This is known as triggered pacing

NBG pacemaker codes

• The pacemaker code is written in a five-letter format as in the table below, using no more letters than necessary.
• For example, the DDDR pacemaker is a dual-chamber paced, dual-chamber sensed, dual response, rate modulated device.
• Information on these older pacemaker codes can be found at NASPE

Pacemaker Types

Hysteresis

• Hysteresis allows more extensive use of the patient intrinsic rhythm and saves battery life. Allows heart to have a slower rate at night Hysteresis rate less than the base rate. Activated by sensing intrinsic electrical activity
• Example. Pacemaker with Base Rate=60. If the patient has NSR at 65, then goes to sleep and the NSR decreases to 55, do we want the pacer to activate and pace at 60. Hysteresis rate set at 50. No pacing until intrinsic rhythm falls below 50, then the pacer paces at 60

Pacemaker Insertion

• Patient Evaluation: Conduct a thorough history, physical exam, ECG, and echocardiography to assess for arrhythmias or structural heart disease.
• Blood Work: CBC, electrolytes, and coagulation profile to ensure there are no contraindications.
• Informed Consent: Explain the procedure, benefits, risks, and potential complications to the patient.
• Prophylactic Antibiotics: Administer antibiotics (e.g., cefazolin) to reduce infection risk.

Pacemaker Insertion Procedure

• Typically performed under local anesthesia with conscious sedation, though general anesthesia may be used in certain cases.
• Venous Access: Access the subclavian or cephalic vein using fluoroscopic guidance.
• Incision: A 5-6 cm incision is made below the collarbone to create a pocket for the pacemaker.
• Lead Insertion: Leads are threaded through the vein into the right atrium and/or right ventricle (depending on the pacemaker type).
• Lead Positioning: Leads are secured to the heart tissue, confirmed by fluoroscopy and electrogram readings.
• Pacemaker Pocket: The pacemaker generator is inserted into the subcutaneous pocket and connected to the leads.
• Programming: The pacemaker is programmed and tested to ensure appropriate pacing and sensing thresholds.
• Wound Closure: The incision is closed with sutures or staples, and a sterile dressing is applied.

Post-Procedure Care

• Monitoring: Continuous ECG monitoring for arrhythmias or pacemaker malfunction in the recovery area.
• Chest X-ray: To confirm lead placement and check for complications like pneumothorax.
• Wound Care: Instruct the patient on wound care and signs of infection.
• Activity Restrictions: Avoid heavy lifting and vigorous shoulder movement for several weeks to allow for proper lead attachment.

Complications of insertion

• Infection: At the incision site or endocarditis.
• Lead Displacement: Leads can dislodge, leading to pacing failure.
• Pneumothorax: A rare complication from subclavian vein access.
• Haemorrhage or Hematoma: At the site of the pacemaker pocket.
• Pacemaker Malfunction: Failure to pace, oversensing, or undersensing.
• Venous Thrombosis: Rare formation of thrombus around the lead.

indications for Temporary Pacing

• Asystole and usually some p wave activity, Complete heart block
• Any Severe haemodynamic disturbance due to bradycardia
• Prevent Bradycardia dependent rhythms e.g. Torsades de pointes
• Overdrive termination of VT, A flutter, TDP
• Acute MI and 2nd/3rd-degree heart block

indications for long term Permanent Pacing

• Symptomatic Bradycardia: Slow heart rate causing dizziness, syncope, or fatigue.
• Atrioventricular (AV) Block: Second-degree or third-degree heart block where electrical signals are delayed or blocked.
• Sick Sinus Syndrome: Dysfunction of the sinus node, causing pauses or slow rhythms.
• Atrial Fibrillation: Combined with medications or ablation to control fast heartbeats.
• Heart Failure: Biventricular pacemakers (CRT) for patients with heart failure and ventricular dyssynchrony.
• Post-MI (Myocardial Infarction): Persistent conduction disturbances following an MI.