Melomed Articles


14 February 2019 - Dr. Vernon Freeman

Pacemakers


Some years ago when the matriarch of a well educated family needed a pacemaker implant, I began to understand how little is known about the subject in the community. The family was mobilizing from all over the country to be at the bedside for this major operation. 

Pacemaker implants in South Africa was pioneered by the Barnard brothers since the late 1960's.  At that early stage the power for the device was supplied by an external battery the size of a PM9 (hope you know what this is).

For a muscle to contract it needs a stimulus (prickle). The stimulus starts from the right atrium (upper chamber) where the heart's own impulse generation resides. The impulse travels to the pumping chambers (ventricles) via the conducting system that carries the impulse to the muscle.

As the impulse travels through the muscle it causes a coordinated contraction that pushes the blood as per our metabolic needs. This process happens more than a hundred thousand times per day during our lifetime. As, in the modern era people live to a higher age, we encounter ever increasing situations where the heart's own (biological) pacing system degenerates. Here (fortunately) our modern technology steps in to save the day.
 
What can go wrong?
The heart loses its ability to generate an impulse (at the rate required by the body) or transfer that impulse to the muscle to tickle the heart muscle to contract. 

A dysfunction may lead to the heart going too slow. Not enough oxygen is supplied to the brain causing a variety of symptoms:
Symptoms Associated With Need for a Pacemaker
Fainting (Blackouts)
Near fainting
Dizziness
Lack of energy
Fatigue
Shortness of breath
Exercise intolerance

The electrocardiogram (ECG) will usually reveal where the problem is: 
1) Impulse generation or 2) Conduction abnormality. The Cardiologist will then discuss the procedure with the patient and family. After answering all additional questions, consent is obtained.

The procedure can be done under general anaesthesia (patient is asleep) or local anaesthesia (patient is awake). The leads (wires) are placed in the heart through the veins that run along the collar bone. The device is implanted below the skin. After closure of the wound, only a scar is left in the shoulder area.
 
Because access is gained to the veins with sharp instruments and leads are placed in a moving heart, potential complications may arise. Rarely the lung or other blood vessels may have been punctured accidently. The leads may have shifted as the patient comes upright and starts moving the arms. All these and other complications are checked before the patient is discharged.

Wound healing usually takes about one week. The patient is provided with a small card that has information regarding the device. The final settings of the device is done months later in an attempt to prolong battery life - which in modern pacemakers can last up to fifteen years.

The following are be matters of concern:
1) Fever
2) Exquisite tenderness over the site
3) Suspected haematoma (swelling)
4) Shortness of breath
5) Frozen (stiff) shoulder
6) Any fluid drainage from the site.
7) Separation of the wound.
Particular warning should be given about getting too close to the following situations.

Mains-driven electric motors, especially if sparking or with faulty suppression (e.g. electrical kitchen equipment, vacuum cleaners, electric razors, electric power drills, motor cycles, lawn mowers, outboard motors, old car engines).

  • Airport weapon detectors. Hand-held detectors are safe.
  • Microwave ovens if faulty with inadequate door seal.
  • High-power radar stations. Hand-held police radar guns are safe.
  • CB radio transmitting systems.
  • Some dental drills (e.g. ultrasonic cleaner).
  • Some equipment used by physiotherapists (e.g. short-wave heat therapy, faradism, etc.).
  • Shop anti-theft equipment. The pacemaker may trigger the alarm system as the patient walks out of the shop, and he or she should warn the shopkeeper.
  • Public libraries have a system that can inhibit the pacemaker.
  • Vibration. Hovercraft, helicopters and other sources of vibration may increase the rate of activity-sensing pacemakers. Patients should be warned that this effect may occur.

  • Pacemakers and sport 
    Vigorous contact sports are best avoided by patients with permanent pacemakers, to avoid injury to the unit (e.g. rugby football, soccer, boxing, judo or karate). Squash should be discouraged if possible. A full golf swing may be uncomfortable with a pacemaker, often more so if it is implanted on the left side.


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