Image showing the cardiac pacemaker or SA node, the normal pacemaker within the electrical conduction system of the heart.
Heart; conduction system. 1. SA node. 2. AV node. 3. Bundle of His. 8. Septum
St. Jude Medical single-lead pacemaker with ruler (released in 2005 )
Ventricular fibrillation (VF) showing disorganized electrical activity producing a spiked tracing on an electrocardiogram (ECG)
Schematic representation of the sinoatrial node and the atrioventricular bundle of His. The location of the SA node is shown in blue. The bundle, represented in red, originates near the orifice of the coronary sinus, undergoes slight enlargement to form the AV node. The AV node tapers down into the bundle of HIS, which passes into the ventricular septum and divides into two bundle branches, the left and right bundles. The ultimate distribution cannot be completely shown in this diagram.
Overview of the system of electrical conduction which maintains the rhythmical contraction of the heart
An ECG in a person with an atrial pacemaker. Note the circle around one of the sharp electrical spikes in the position where one would expect the P wave.
Broad classification of arrhythmias according to region of heart required to sustain the rhythm
An ECG of a person with a dual chamber pacemaker
Normal sinus rhythm, with solid black arrows pointing to normal P waves representative of normal sinus node function, followed by a pause in sinus node activity (resulting in a transient loss of heartbeats). Note that the P wave that disrupts the pause (indicated by the dashed arrow) does not look like the previous (normal) P waves – this last P wave is arising from a different part of the atrium, representing an escape rhythm.
Principle of ECG formation. Note that the red lines represent the depolarization wave, not bloodflow.
ECG rhythm strip of a threshold determination in a patient with a temporary (epicardial) ventricular pacemaker. The epicardial pacemaker leads were placed after the patient collapsed during aortic valve surgery. In the first half of the tracing, pacemaker stimuli at 60 beats per minute result in a wide QRS complex with a right bundle branch block pattern. Progressively weaker pacing stimuli are administered, which results in asystole in the second half of the tracing. At the end of the tracing, distortion results from muscle contractions due to a (short) hypoxic seizure. Because decreased pacemaker stimuli do not result in a ventricular escape rhythm, the patient can be said to be pacemaker-dependent and needs a definitive pacemaker.
Different wave shapes generated by different parts of the heart's action potential
Right atrial and right ventricular leads as visualized under x-ray during a pacemaker implant procedure. The atrial lead is the curved one making a U shape in the upper left part of the figure.
Single-chamber VVIR/AAIR pacemaker
Dual-chamber DDDR pacemaker
Three leads can be seen in this example of a cardiac resynchronization device: a right atrial lead (solid black arrow), a right ventricular lead (dashed black arrow), and a coronary sinus lead (red arrow). The coronary sinus lead wraps around the outside of the left ventricle, enabling pacing of the left ventricle. Note that the right ventricular lead in this case has two thickened aspects that represent conduction coils and that the generator is larger than typical pacemaker generators, demonstrating that this device is both a pacemaker and a cardioverter-defibrillator, capable of delivering electrical shocks for dangerously fast abnormal ventricular rhythms.
Posteroanterior and lateral chest radiographs of a pacemaker with normally located leads in the right atrium (white arrow) and right ventricle (black arrowhead), respectively.
Two types of remote monitoring devices used by pacemaker patients
In 1958, Arne Larsson (1915–2001) became the first to receive an implantable pacemaker. He had 26 devices during his life and campaigned for other patients needing pacemakers.
Illustration of implanted cardiac pacemaker showing locations of cardiac pacemaker leads
The first lithium-iodide cell-powered pacemaker. Invented by Anthony Adducci and Art Schwalm. Cardiac Pacemakers Inc. 1972

An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or just pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart either the upper atria, or lower ventricles to cause the targeted chambers to contract and pump blood.

- Artificial cardiac pacemaker

The pacemaking signal generated in the sinoatrial node travels through the right atrium to the atrioventricular node, along the Bundle of His and through bundle branches to cause contraction of the heart muscle.

- Electrical conduction system of the heart

By doing so, the pacemaker regulates the function of the electrical conduction system of the heart.

- Artificial cardiac pacemaker

Sometimes an ectopic pacemaker sets the pace, if the SA node is damaged or if the electrical conduction system of the heart has problems.

- Cardiac pacemaker

Cardiac arrhythmias can cause heart block, in which the contractions lose any useful rhythm.

- Cardiac pacemaker

Dysfunction of the conduction system can cause irregular heart rhythms including rhythms that are too fast or too slow.

- Electrical conduction system of the heart

In humans, and sometimes in other animals, a mechanical device called an artificial pacemaker (or simply "pacemaker") may be used after damage to the body's intrinsic conduction system to produce these impulses synthetically.

- Cardiac pacemaker

Arrhythmias are due to problems with the electrical conduction system of the heart.

- Arrhythmia

Treatments may include medications, medical procedures such as inserting a pacemaker, and surgery.

- Arrhythmia

When an arrhythmia cannot be treated by medication an artificial pacemaker may be surgically inserted to control the conduction system.

- Electrical conduction system of the heart

The first of arrhythmia is a result of enhanced or abnormal impulse formation originating at the pacemaker or the His-Purkinje network.

- Arrhythmia

Any events that were stored since the last follow-up, in particular arrhythmias such as atrial fibrillation. These are typically stored based on specific criteria set by the physician and specific to the patient. Some devices have the availability to display intracardiac electrograms of the onset of the event as well as the event itself. This is especially helpful in diagnosing the cause or origin of the event and making any necessary programming changes.

- Artificial cardiac pacemaker
Image showing the cardiac pacemaker or SA node, the normal pacemaker within the electrical conduction system of the heart.

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