Artificial cardiac pacemaker

St. Jude Medical single-lead pacemaker with ruler (released in 2005 )
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.
An ECG of a person with a dual chamber pacemaker
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.
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

Medical device that generates electrical impulses delivered by electrodes to cause the heart muscle chambers (the upper, or atria and/or the lower, or ventricles) to contract and therefore pump blood.

- Artificial cardiac pacemaker

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Implantable cardioverter-defibrillator

A Guidant Corporation ICD device
Illustration of Implantable Cardioverter Defibrillator (ICD)
A single chamber ICD with its right ventricular lead connected into the header; note, starting from the end of the lead, the tip and adjacent first ring, used to sense the cardiac electrical activity and stimulate the right ventricle, the coil and the two rings for atrial sensing.
A normal chest X-ray after placement of an ICD, showing the ICD generator in the upper left chest and the ICD lead in the right ventricle of the heart. Note the 2 opaque coils along the ICD lead.
S-ICD lead and generator position
Lead II electrocardiogram (known as "rhythm strip") showing torsades de pointes being shocked by an implantable cardioverter-defibrillator back to the patient's baseline cardiac rhythm.

An implantable cardioverter-defibrillator (ICD) or automated implantable cardioverter defibrillator (AICD) is a device implantable inside the body, able to perform defibrillation, and depending on the type, cardioversion and pacing of the heart.

Heart block

Disorder in the heart's rhythm due to a fault in the natural pacemaker.

ECG showing types of heart block
Conduction system of the heart
Sinus rhythm with acute inferior infarction complicated by Type I AV block manifest in the form of 5:4 Wenckebach periods; R-P/P-R reciprocity.
Sinus tachycardia with complete AV block and resulting junctional escape

Despite the severe-sounding name, heart block may cause no symptoms at all in some cases, or occasional missed heartbeats in other cases (which can cause light-headedness, syncope (fainting), and palpitations), or may require the implantation of an artificial pacemaker, depending upon exactly where in the heart conduction is being impaired and how significantly it is affected.

Cardiac pacemaker

Initiated by electrical impulses known as action potentials.

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

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.

Electrocardiography

Process of producing an electrocardiogram , a recording of the heart's electrical activity.

ECG of a heart in normal sinus rhythm
Normal 12-lead ECG
A 12-lead ECG of a 26-year-old male with an incomplete right bundle branch block (RBBB)
A patient undergoing an ECG
An EKG electrode
Proper placement of the limb electrodes. The limb electrodes can be far down on the limbs or close to the hips/shoulders as long as they are placed symmetrically.
Placement of the precordial electrodes
The limb leads and augmented limb leads (Wilson's central terminal is used as the negative pole for the latter in this representation)
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Diagram showing the contiguous leads in the same color in the standard 12-lead layout
QRS is upright in a lead when its axis is aligned with that lead's vector
Schematic representation of a normal ECG
Measuring time and voltage with ECG graph paper
Animation of a normal ECG wave
Formation of limb waveforms during a pulse
An early commercial ECG device (1911)
ECG from 1957
Use of real time monitoring of the heart in an intensive care unit in a German hospital (2015), the monitoring screen above the patient displaying an electrocardiogram and various values of parameters of the heart like heart rate and blood pressure

Among other things, an ECG can be used to measure the rate and rhythm of heartbeats, the size and position of the heart chambers, the presence of any damage to the heart's muscle cells or conduction system, the effects of heart drugs, and the function of implanted pacemakers.

Bradycardia

Slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram.

Sinus bradycardia seen in lead II with a heart rate of about 50BPM
Illustration comparing the ECGs of a healthy person (top) and a person with bradycardia (bottom): The points on the heart where the ECG signals are measured are also shown.

Treatment often consists of the administration of atropine and cardiac pacing.

Heart failure

Set of manifestations caused by the failure of the heart's function as a pump supporting the blood flow through the body; its signs and symptoms result from a structural and/or functional abnormality of the heart, that disrupts its filling with blood or its ejecting of it during each heart beat.

A man with congestive heart failure and marked jugular venous distension. External jugular vein marked by an arrow.
Signs and symptoms of severe heart failure
Severe peripheral pitting edema
Kerley B lines in acute cardiac decompensation. The short, horizontal lines can be found everywhere in the right lung.
Model of a normal heart (left); and a weakened heart, with over-stretched muscle and dilation of left ventricle (right); both during diastole
Chest radiograph of a lung with distinct Kerley B lines, as well as an enlarged heart (as shown by an increased cardiothoracic ratio, cephalization of pulmonary veins, and minor pleural effusion as seen for example in the right horizontal fissure. Yet, no obvious lung edema is seen. Overall, this indicates intermediate severity (stage II) heart failure.
Siderophages (one indicated by white arrow) and pulmonary congestion, indicating left congestive heart failure
Ultrasound showing severe systolic heart failure
Congestive heart failure with small bilateral effusions
Kerley B lines

Sometimes, depending on the cause, an implanted device such as a pacemaker or an implantable cardiac defibrillator may be recommended.

Cardiac electrophysiology

Science of elucidating, diagnosing, and treating the electrical activities of the heart.

Drawing of the ECG, with labels of intervals

Other therapeutic modalities employed in this field include antiarrhythmic drug therapy and implantation of pacemakers and implantable cardioverter-defibrillators (ICD).

Medtronic

American medical device company based in Ireland for tax purposes.

Medtronic operational headquarters in Fridley, Minnesota, a suburb of Minneapolis
Medtronic's original headquarters in St. Anthony, Minnesota
Medtronic legal headquarters, 20 Lower Hatch Street, Dublin 2, Ireland
O-arm Surgical Imaging System. Federal Center of Neurosurgery in Tyumen, 2013

The deficiencies of the artificial pacemakers of the day were made painfully obvious following a power outage over Halloween in 1957, which affected large sections of Minnesota and western Wisconsin.

Arrhythmia

Too fast or too slow.

Ventricular fibrillation (VF) showing disorganized electrical activity producing a spiked tracing on an electrocardiogram (ECG)
Broad classification of arrhythmias according to region of heart required to sustain the rhythm
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.

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

Cardiac resynchronization therapy

Chest radiographs of cardiac resynchronization therapy with defibrillator (CRT-D) in an individual with dilated cardiomyopathy after mitral valve replacement (MVR). The leads are: - Atrial lead at the right appendage - Right ventricular lead at the apex - Left ventricular lead through the coronary sinus.

Cardiac resynchronisation therapy (CRT or CRT-P) is the insertion of electrodes in the left and right ventricles of the heart, as well as on occasion the right atrium, to treat heart failure by coordinating the function of the left and right ventricles via a pacemaker, a small device inserted into the interior chest wall.