…pacemaker detects electrical activity that it incorrectly interprets as atrial (P wave) or ventricular activity (R wave). The signals causing oversensing may not be visible…

…Stimulation threshold is the minimum amount of energy required to reach threshold and evoke an action potential. The intensity of the electrical stimulus is described…

…or passive , meaning that the cathode is not inserted into the myocardium but instead the lead is anchored to the myocardium via tines (Figure 1…

…automaticity) in the sinoatrial node. This simply means that the sinoatrial node discharges electrical impulses at a higher frequency than normal. Similar to sinus rhythm…

…maneuvers (Valsalva maneuver, carotid sinus [baroreceptor] stimulation). It is common to discover SB in healthy young individuals who are not well trained. This is also…

…causes, diagnosis & management This article covers the fundamental principles of atrioventricular (AV) blocks, which are classified into three types: first degree, second degree, and third…

…or syncope. ARVC can, however, cause ventricular tachycardia, which may degenerate into ventricular fibrillation at any age. Exercise, or any other activity causing adrenergic stimulation…

…action potential, automaticity and electrical vectors Video lecture The following video lecture summarises this chapter. The action potential includes a depolarization (activation) followed by a…

…hyperthyroidism or an untreated underlying cause make recurrence all but certain and argue against elective cardioversion. Anticoagulation before cardioversion After cardioversion the atrium does not…

…of the normal heart axis. Figure 1. The electrical axis of the heart (heart axis). As evident from the figure, the normal heart axis is…

…range of normal heart axis. Figure 38. The electrical axis of the heart (heart axis). As evident from the figure, the normal heart axis is…

ECG Video lecture: Assessment of the electrical axis of the heart

…in most cases of significant RVH, although it is not typically classified as a formal diagnostic criterion for the condition [17]. Left Axis Deviation (LAD…

…focus on ventricular fibrillation and pulseless electrical activity (PEA). These are highly lethal arrhythmias that lead to death if cardiopulmonary resuscitation is not started immediately…

…for ventricular fibrillation, where urgent reversion to sinus rhythm is required. The rationale for electrical therapy over drugs is that, under monitored conditions, a controlled…

…the heart rate, the electrical axis and the waveform in the newborn differ markedly from adult reference values and normalise gradually through childhood. The interpretation…

…children) Principles of ECG leads, lead anatomy and electrical vectors have been discussed in the chapter The ECG Leads. Acquisition of ECGs in pediatric patients…

…your own region. The time limit is not a guarantee. Where the stroke risk is high or the time of onset uncertain, choose the more…

…or the use of antiarrhythmic drugs. In such clinical scenarios, an atypical ECG presentation does not definitively exclude a typical flutter circuit utilizing the CTI…

…or electrical instability. Posterior infarction may occur in patients with a clinically unstable acute coronary syndrome, but the examination does not reliably establish or exclude…

…The contemporary understanding of AF has evolved significantly; it is no longer viewed merely as an electrical anomaly but as a progressive, complex atrial myopathy…

…the greater the probability that the rhythm has deteriorated into PEA or asystole, and therefore the worse the prognosis. This does not always hold true…

…anaphylactic cardiac arrests present with pulseless electrical activity (PEA) as the initial rhythm, while the remainder manifest ventricular fibrillation (VF) or asystole ( Ebo et al…

…arrhythmia is classified instead as an ectopic atrial rhythm (EAR) . Ectopic atrial tachycardia (EAT) most commonly occurs in individuals with underlying structural or electrical heart…

…which delivers the electrical impulse to the posterior and inferior walls of the left ventricle. Anatomical or functional block in the anterior fascicle leads to…

…from the right ventricle. The electrical impulse will propagate through the left ventricle partially or entirely outside the specialized conduction system. This slower conduction results…

…right ventricle relies on electrical impulses originating from the left ventricle. However, these impulses propagate slowly as they travel partially or entirely outside the specialized…

…LVH) and right ventricular hypertrophy (RVH). The electrical vector of the left ventricle is enhanced in LVH, which results in large R waves in left…

…the terms unipolar leads and bipolar leads are not recommended because all ECG leads are bipolar, since they compare electrical currents in two measurement points…

…In contrast, modalities like echocardiography and ECG typically identify ischemia at later stages, when functional or electrical alterations are evident. Subjective symptoms (i.e. chest…

…usually II or V5, and the U wave must not be included. Electrical axis Electrical axis Interpretation : : −30° to +90° Normal −30° to −90° Left…

…or pericardiotomy instead. Relative: uncorrected coagulopathy, thrombocytopenia and ongoing anticoagulant treatment. In tamponade with shock the coagulation is corrected in parallel with the procedure, not…

…after cardiac arrest with persisting electrical activity. Overdrive pacing in bradycardia dependent torsades de pointes. Standby pacing — pads applied but the device not switched on —…

…137 (108) 65–133 (100) 63–129 (92) 66–120 (86) 50 – 120 Electrical axis (degrees) 58–168 ( 135) 65–171 ( 134) 76–168 ( 133…

… or angina occurring after a recent MI. Myocardial injury is separate from MI. It refers to cardiac troponin release that does not fulfil the criteria…

…bradyarrhythmic arrest or pulseless electrical activity (PEA), presenting as cardiovascular collapse and cardiac arrest. Evaluation and Physical Examination The source material does not provide specific…

…test does not define the structure or composition of coronary atherosclerotic plaque, identify plaques at high risk of rupture, or determine whether ischaemia would occur…

…Implantable loop recorders are diagnostic devices rather than pacing or defibrillation systems, but their stored data may also be affected by perioperative electromagnetic interference (EMI)…

…to establish a working diagnosis of STEMI rapidly, identify haemodynamic or electrical instability and determine the appropriate reperfusion pathway. Important early clinical priorities include: Recognition…

…point depression). The reason for such electrical potential difference is that not all ventricular myocardial cells will finish their action potential simultaneously. Myocardial cells which…

…features characteristic of biventricular hypertrophy. Biventricular hypertrophy ECG In case the ECG or other examinations suggest left ventricular hypertrophy (LVH), one should suspect concomitant right…

…presentation is notoriously heterogeneous, ranging from lifelong asymptomatic ECG anomalies to electrical storm and sudden cardiac arrest (SCA) as the index presentation. Over the past…

…resulting in obstruction. Central nervous system (CNS) injuries might cause apnea or hypoventilation. Respiratory conditions : Tension pneumothorax Drowning Airway obstruction Hanging Pneumonia High altitude sickness…

…and can guide resuscitative efforts. If the patient presents with hypotension or has a lactate level exceeding 4 mmol/l, commence an intravenous fluid resuscitation…

…when cells in the sinoatrial node discharge an action potential that spreads as an electrical impulse through the atria and – via the atrioventricular node – to…

…V1 or S V2 ≥30 mm R V5 or R V6 ≥30 mm 3 Discordant ST T change in a patient not on digoxin treatment…

…The ECG in Brugada syndrome Brugada syndrome is a rare channelopathy (an electrical disorder caused by mutations in cardiac ion channels) which predisposes the individual…

…malignant ventricular arrhythmias, or sudden cardiac death. The resulting extensive ischemia causes immediate myocardial stunning (akinesia) and electrical instability. Fewer than 1% of patients with…

ECG Genetic and miscellaneous conditions Eletrical alternans: an ECG sign of pericardial effusion and cardiac tamponade The pericardial space (cavity) always contains a small amount…

…chapters (see The 3 Phase Model of Cardiac Arrest). Both chest compressions and defibrillation are paramount in restoring cardiac electrical activity, hence rhythm and contractility…

…block (second or third degree AV block). A pacemaker is often necessary in individuals with first degree AV block and wide QRS complexes. Treatment of…

…a sudden and random electrical event. An excerpt from the article follows: [...] Of every 10 such victims, the heart in 6 or 7 showed no…

…1930s, to a routine, safe, and sophisticated treatment used worldwide. Artificial pacemakers have benefitted immensely from advances in engineering, notably with the advent of transistors…

…137 (108) 65–133 (100) 63–129 (92) 66–120 (86) 50 – 120 Electrical axis (degrees) 58–168 ( 135) 65–171 ( 134) 76–168 ( 133…

…Sinoatrial (SA) block implies that the impulses discharged in the sinoatrial node are either not conducted to the atria or are so with a delay…

…Sudden cessation of tissue perfusion as a result of cardiac or vascular condition. May reverse spontaneously (e.g., vasovagal syncope) or with treatment (e.g.…

…which require different treatment strategies to maximize survival (Table 1). Phase Period Optimal treatment Electrical phase 0 to 4 minutes Defibrillation Circulatory phase 4 to…

…to the ventricles is normal. The PR interval must not be shorter than 120 msec or longer than 220 msec. The PR segment is the…

…AV block is a very serious condition because escape rhythms may (1) not occur, (2) occur transiently, or (3) occur but generate insufficient cardiac output…