…to the high density of myocardium. It follows that myocardium generates reflections with high amplitude and low Doppler shift. To analyze reflections from the myocardium…

…Definition and pathophysiology Cardiac implantable electronic devices (CIEDs) include permanent pacemakers, implantable cardioverter defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. Implantable loop recorders are…

…at low and high heart rate, the behavior of the pacemaker in the presence and absence of intrinsic cardiac activity, Modern pacemakers are packed with…

…etc. Most cases of malfunction are associated with the electronics in the pulse generator or dislodgement or fracture of the leads. External causes are less…

…The cardiac cycle starts when cells in the sinoatrial node discharge an action potential that spreads as an electrical impulse through the atria and – via…

ECG Introduction to ECG interpretation Cardiac electrophysiology: Membrane potential, action potential, automaticity and electrical vectors Video lecture The following video lecture summarises this chapter. The…

…induce spontaneous electrical activity in myocardial cells. CPP below 15 mmHg is insufficient to generate cardiac electrical activity. CPP = P aortic P right atrium…

…such an extent that chest compressions fail to generate stroke volumes. Consequently, addressing reversible causes of cardiac arrest becomes more critical than performing chest compressions…

CPR The course from sudden cardiac arrest (SCA) to death follows a pathophysiological process that affects the effectiveness of the interventions. Numerous studies demonstrate that…

…Systemic Inflammatory Response Syndrome (SIRS). Body temperatures surpassing 40°C (104°F) are potentially hazardous and may precipitate cardiac arrest. The classification of hyperthermia is delineated in…

[calc_hcmrisk] Predicting Sudden Cardiac Death in Hypertrophic Cardiomyopathy (HCM) Hypertrophic Cardiomyopathy (HCM) is a genetic cardiomyopathy characterized by left ventricular hypertrophy. It is the…

…Atrial Fibrillation and Atrial Thromboembolism Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a profound driver of global cardiovascular morbidity and mortality…

…and Pathophysiological Basis High sensitivity cardiac troponin (hs cTn) assays detect circulating troponin released from injured cardiomyocytes at substantially lower concentrations than earlier generation assays…

ECG Hypertrophy and dilatation Principles of atrial and ventricular enlargement (hypertrophy and dilatation) Cardiac chamber enlargement refers to abnormally large atria or abnormally large ventricles…

…15 seconds, with submillimetre spatial resolution. Iodinated contrast is generally required for coronary angiography because the intrinsic contrast between the cardiac chambers, blood pool, and…

…EAT, or atrial tachycardia) arises when an ectopic focus within the atria generates electrical impulses at a rate exceeding that of the sinoatrial (SA) node…

…time dependent inward currents. This process creates early afterdepolarisations (EADs) that generate premature ventricular contractions (PVCs) and increases transmural dispersion of repolarisation, thereby facilitating reentry…

…asystole represent severe manifestations of impulse generation or conduction failure. The pathophysiology of these events may stem from reversible causes, including hypovolemia, hypoxia, cardiac tamponade…

…always suspect pacemaker mediated tachycardia. CRT devices (cardiac resynchronization therapy) may also cause tachycardias, and these devices produce slightly narrower QRS complexes (because they stimulate…

…individuals have developed a highly efficient left ventricle, capable of generating sufficient cardiac output at low heart rates. During vasovagal syncope (e.g during intense…

…depth). With current strategies, compressions and ventilations can generate a cardiac output equivalent to 15 25% of normal output ( Duggal et al ). This, in conjunction…

…(2) occur transiently, or (3) occur but generate insufficient cardiac output. If no escape rhythm occurs, cardiac arrest will ensue. Progression from first degree AV…

…volume. The drawback of stroke volume as a measure of left ventricular function is that it ignores the ability of the ventricle to generate pressure…

…appropriate. Contraindications Respiratory arrest, agonal breathing or cardiac arrest — intubate. Inability to protect the airway: a reduced level of consciousness not attributable to hypercapnia, marked…

…ventilation is difficult or inadequate. The primary airway in cardiac arrest when the person ventilating is not experienced in intubation. Planned anaesthesia for short procedures…

…and contraindications. Singh–Vaughan Williams classification of antiarrhythmic drugs Antiarrhythmic drugs affect the function of cardiac ion channels. These agents are classified according to the…

…clinical presentation, bleeding risk, the anticipated need for non cardiac surgery, procedural complexity, and the relative merits of PCI and coronary artery bypass grafting (CABG…

…knowledge of age related variations in the ECG, as well as cardiac diseases that may affect infants and children. Physiological and anatomical development during infancy …

…cells. The resulting voltage gradient between normal and ischaemic myocardium generates currents of injury that are expressed on the surface ECG as ST segment displacement…

…and contraindications. Singh–Vaughan Williams classification of antiarrhythmic drugs Antiarrhythmic drugs affect the function of cardiac ion channels. These agents are classified according to the…

…knowledge of age related variations in the ECG, as well as cardiac diseases that may affect infants and children. Physiological and anatomical development during infancy …

…wall thickness (myocardial thickness). The left ventricle must generate sufficient contractile force to overcome the pressure in the aorta. The greater the pressure in the…

…surface). This is because the electrical potentials generated by the sinoatrial node are much too small to be detected on the surface ECG. Intracardiac electrodes…

…compare electrical currents in two measurement points. The electrophysiological basis of the ECG leads The movement of charged particles generates an electric current. In electrocardiology…

…dysfunction (heart failure) and arrhythmias. The annual risk of sudden cardiac arrest is <1% and median survival is 3 years. Long term prognosis in aortiv…

…of intense epidemiological debate, likely reflecting the catabolic state of advanced HF (cardiac cachexia) rather than a protective effect of adiposity. Etiology and underlying causes…

…Hypertrophic cardiomyopathy causes concentric hypertrophy Hypertrophic cardiomyopathy causes concentric hypertrophy, which means that the generated myocardium allocates space in the ventricular cavity. In concentric hypertrophy…

…via Glycoprotein IIb/IIIa cross linking). Concurrent activation of the coagulation cascade leads to thrombin generation and fibrin deposition, culminating in a partially or fully…

…and thus generate an action potential that will spread through the myocardium. Components of an artificial pacemaker Pacemakers consist of an implantable pulse generator (IPG…

Echocardiography Generating the ultrasound image The ultrasound transducer generates short bursts (pulses) of ultrasound waves. Reflected ultrasound waves are analyzed by the machine during the…

Echocardiography The ultrasound transducer & piezoelectric crystals The ultrasound transducer generates ultrasound (ultrasonic) waves. The transducer is held with one hand and its position and angle…

…pressure control. Mechanism of action Nitroprusside provides nitric oxide (NO) that induces vasodilatation of both arterioles and veins via generation of cyclic GMP, which then…

…fluids in the human body. Sound waves arise when a sound source generates mechanical vibrations in the particles of the medium. These vibrations continue to…

…pressure control. Mechanism of action Nitroglycerin provides nitric oxide (NO) that induces vasodilatation (of both arterioles and veins) via generation of cyclic GMP, which then…

…occult structural abnormality. IVUS IVUS generates images by transmitting ultrasound from an intracoronary catheter and recording echoes reflected from the vessel wall. Contemporary systems use…

…segment ECG interpretation starts with assessment of the P wave and PR interval. The P wave is generated by depolarization (activation, contraction) of the atria…

…portion of the P wave is positive but the terminal portion is slightly negative (the vector generated by left atrial activation heads away from V1)…

…patients with a very low probability of obstructive CAD, testing may generate false positive results and unnecessary downstream procedures. In patients with a high probability…

…fraction during submaximal exercise testing. Ejection fraction reserve is the available reserve in ejection fraction that can be generated during exercise. Effect of preload and…

…The ECG grid. The x axis represents time and y axis represents amplitude of the electrical signals generated in the myocardium. The same ECG grid…

…90° width and 15 cm depth, approximately 200 ultrasound lines are required and this takes about 40 milliseconds (ms) to generate. As illustrated previously (Axial…

…hydroxide ions are generated at the negative pole of the battery and produce a liquefactive necrosis that can reach the septal cartilage within a few…

…residual stenosis Long lesion length Diabetes Untreated edge dissection DES have reduced restenosis compared with BMS, and newer generation DES have improved outcomes further. Nevertheless…

…greater than the positive area. Electrical vectors that engender the QRS complex Depolarization of the ventricles generate three large vectors, which explains why the QRS…

…wires, etc ), they may generate significant reflections which are detected by the transducer. These reflections are interpreted as originating from the main beam. As the…

…majority of WCTs originate from impulses generated in the ventricles (ventricular tachycardia being the most common arrhythmia). Any impulses generated in the ventricles will result…

…the transducer, the billions of erythrocytes in the blood will collectively generate enough reflections to be detected and analyzed by the ultrasound machine. Figure 2…

…three waves. Since the electrical vector generated by the left ventricle is many times larger than the vector generated by the right ventricle, the QRS…

…discharged near the atrioventricular node, the atria will be depolarized in the opposite direction and thus generate a negative (retrograde) P wave (Figure 2). Thus…

…the calculations will be uncertain. This is explained by the fact that each ultrasound pulse generates a snapshot of blood flow. The greater the number…