…intraventricular conduction defect. In severe cases, bradycardia may progress to hemodynamic instability, presenting as shock or cardiac arrest manifesting as bradyarrhythmic arrest, asystole, or pulseless…

Conduction defects ECG Right bundle branch block (RBBB) Right bundle branch block (RBBB) is due to an anatomical or functional dysfunction in the right bundle…

…Ventricular fibrillation or asystole may occur early due to the massive ischemia. Complete LMCA occlusion is typically fatal within minutes, hence its designation as the…

…within the atrioventricular node, as long as it encounters excitable tissue. As it circulates within the node, it emits impulses both upwards to the atria…

…from the atria to the ventricles may be delayed or blocked. These conditions are referred to as atrioventricular (AV) blocks , subdivided according to the degree…

…direction ), from the ventricles to the atrial ( retrograde direction ) or both. Accessory pathways do not display the slow conduction that the atrioventricular node does, and…

…etc .) are warranted. Management of AV blocks aims to restore atrioventricular conduction either pharmacologically or by means of artificial pacemakers. Both methods may be used…

…or near, the atrioventricular (AV) node. The most common rhythm arising in the AV node is junctional rhythm , which may also be referred to as…

…to atrial fibrillation with wide QRS complexes due to bundle branch blocks or other conduction defects. However, in rare instances, it may be due to…

Conduction defects ECG First degree AV block: ECG criteria, clinical characteristics & management This chapter discusses first degree atrioventricular (AV) block, also referred to as 1st…

…be viewed as a tendency to exhaust the conduction capacity. It starts with the successful conduction of an atrial impulse (either with normal or abnormal…

…In severe cases, bradycardia may progress to bradyarrhythmic arrest or pulseless electrical activity (PEA), presenting as cardiovascular collapse and cardiac arrest. Evaluation and Physical Examination…

…given as repeated intravenous bolus injections or as a constant dose infusion. Bolus regime : • 20 mg IV bolus over 2 minutes, followed by 20 to…

…1.25 to 5 mg IV followed by 2.5–15 mg IV every 3 to 6 hours. Adverse effects Vomiting. Dizziness. Nausea. Atrioventricular blocks…

…the A H interval, frequently manifesting as transient first , second , or third degree AV nodal block lasting up to a few seconds. His Purkinje conduction…

…standing to determine if orthostatic hypotension is present. High risk features on history include: New onset of chest discomfort, abdominal pain, shortness of breath, or…

…an action potential that spreads as an electrical impulse through the atria and – via the atrioventricular node – to the ventricles. As the impulse spreads through…

…none of the ECG changes or arrhythmias are unique to digoxin. One should always suspect digoxin as the trigger of an arrhythmia (in patients using…

…Understanding the basic principles of exercise physiology is essential to conduct and evaluate the exercise stress test. Exercise induces physiological changes such as increased ventilation…

…duration of 120 ms (0.12 s) or more is required to diagnose a complete left bundle branch block . In addition to prolonged QRS duration…

…the reversed direction of atrial activation) and may be located before or after the QRS complex. This rhythm is referred to as a junctional rhythm …

…there is a gradual exhausting of the conduction before it is completely blocked, is referred to as Wenckebach phenomenon (also referred to as Wenckebach periodicity )…

…segment as the baseline. Several conditions can reduce the ability of the atrioventricular (AV) node to conduct the atrial impulse to the ventricles. As the…

…other. This condition is referred to as atrioventricular (AV) dissociation. Importantly, for the ventricles to have any electrical (and thus pumping) activity at all, an…

…impulses (P waves) are blocked by the atrioventricular node. An escape rhythm arises (cardiac arrest ensues otherwise), which may have narrow or wide QRS complexes…

…drugs or amiodarone. In these instances, the flutter rate may be reduced to less than 200 beats per minute, which paradoxically facilitates 1:1 atrioventricular…

…or worsening hemodynamics, and signs of digoxin toxicity. Toxicity can manifest as sinus bradycardia or sinus arrest, atrioventricular (AV) node block, and junctional, fascicular, or…

…in Figure 3. If an atria becomes enlarged (typically as a compensatory mechanism) its contribution to the P wave will be enhanced. Enlargement of the…

…PR interval, while leaving the QRS duration largely unchanged. Continuous ECG monitoring is mandated during hospital initiation to detect excessive QT prolongation, proarrhythmia, and severe…

…silent and detected only by electrocardiographic monitoring. Syncope may result from transient atrioventricular block, asystole, or ventricular tachycardia. Prolonged spasm can cause acute myocardial infarction…

…wave. Increasing the paper speed to 50 mm/s or applying carotid massage (which increases the atrioventricular block) will be helpful in such situations. Figure…

…slow impulse conduction through the atrioventricular node. Transmission of the action potential between contractile myocardial cells is also slow, owing to the scarcity of gap…

…slow impulse conduction through the atrioventricular node. The PR segment serves as the baseline (also referred to as the reference line or isoelectric line ) of…

…cardiologists – particularly interventional cardiologists – this knowledge is of critical importance as they must be able to directly pinpoint where the coronary artery occlusion is located…

…as ectopic pacemaker foci. The term “ectopic” is often omitted in clinical practice, and these arrhythmias are commonly referred to simply as atrial tachycardia or…

…All atrial impulses (P waves) are blocked by the atrioventricular node. An escape rhythm arises (cardiac arrest ensues otherwise), which may have narrow or w

…in bundle branches or fascicles may block the impulse completely. Such a block in the left bundle branch is simply referred to as left bundle…

…following scenarios: Inability to exercise due to physical limitations. Contraindications to exercise, such as unstable angina, severe aortic stenosis, decompensated heart failure, or aortic aneurysm…

…will be refractory). If the premature atrial impulse reaches the atrioventricular node (or bundle of His) while it is completely refractory, the impulse will be…

…off PDA, it is referred to as a left dominant system ). In patients with right dominance the RCA supplies the atrioventricular (AV) node . In 60…

…there is atrioventricular conduction, these rhythms typically compete which is seen on the ECG with sinus rhythm alternating with accelerated ventricular rhythm. As mentioned in…

…to the European Society for Cardiology, 2800 adults per 1 million individuals have congenital heart defects, and half of them have moderate or complicated defects…