…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…

…and programming. The simplest pacemaker systems consist of a pulse generator and one lead, which is located either in the right atrium or the right…

…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…

…dependent patients, patients with CRT, and ICD recipients undergoing procedures likely to generate EMI. Assess pacing dependence Determining pacing dependence is central to planning. If…

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…

…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…

…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…

…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…

…and absence of a palpable pulse. Ventricular contraction has ceased or unable to generate perfusion. SCD (sudden cardiac death) : Death resulting from sudden cardiac arrest…

…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…

…TdP). Drug induced LQTS and TdP represent a multifactorial clinical entity that typically emerges when multiple modifiable and non modifiable risk factors converge. The electrophysiological…

…More broadly, bradyarrhythmic arrest and asystole represent severe manifestations of impulse generation or conduction failure. The pathophysiology of these events may stem from reversible causes…

…Myocardial ischemia and infarction Definition and Clinical Role Coronary computed tomographic angiography (CCTA) is a non invasive anatomical examination that depicts the coronary arterial lumen…

…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)…

…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…

…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…

…systole. Transesophageal echocardiography and surgical pathology demonstrate that over 90% of thrombi in non valvular AF originate within this specific anatomical cul de sac [19] …

…ecstasy) or amphetamines. In either scenario, there is sustained muscle activation, leading to marked heat generation, acidosis, and the subsequent development of hyperkalemia. This condition…

…cells which respond by contracting. The action potential generates electrical currents that give rise to the classical ECG waveforms presented here. Activation of the atria…

…Because ions are electrically charged, their movement generates an electrical current. This means that the propagation (spread) of the action potential is equal to the…

…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…

…Pacemaker stimulation generates a stimulation artifact ("pacemaker spike"). Older pacemakers generate large and visible spikes, whereas newer models may generate very minute or even invisible…

…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…

…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…

…infarction. Sinus Node Dysfunction (SND) – Sinus node dysfunction implies that the cells of the sinoatrial node are defective and fail to generate electrical impulses. Side…

…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…

…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…

…rhythms may (1) not occur, (2) occur transiently, or (3) occur but generate insufficient cardiac output. If no escape rhythm occurs, cardiac arrest will ensue…

…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…

…compressions ineffective. For instance, a traumatic hemorrhage can deplete intravascular volume to such an extent that chest compressions fail to generate stroke volumes. Consequently, addressing…

…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…

…Preparation and equipment A device capable of both CPAP and bilevel ventilation, or alternatively flow generated CPAP with a PEEP valve. Masks in several sizes…

…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…

…The laryngeal mask is a compromise and does not protect the airway completely. Relative contraindications: A high risk of aspiration: a non fasted patient, ileus…

…Dofetilide, Ibutilide, Sotalol Class IV Non dihydropyridine L type Ca 2+ channel blockers Diltiazem, Verapamil Singh–Vaughan Williams classification of antiarrhythmic drugs. Bold text indicates…

…The HCM Risk SCD score aims to identify individuals with a high risk of SCD and determine whether an implantable cardioverter defibrillator (ICD) is warranted…

…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…

…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…

…larger than the right ventricle, the QRS complexes are dominated completely by the electrical currents generated by the left ventricle. This explains why leads V4…

…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…

…Dofetilide, Ibutilide, Sotalol Class IV Non dihydropyridine L type Ca 2+ channel blockers Diltiazem, Verapamil Singh–Vaughan Williams classification of antiarrhythmic drugs. Bold text indicates…

…artery (LMCA) departs from the left coronary cusp (LCC). NCC = non coronary cusp. Natural course and prognosis in aortic stenosis Aortic stenosis is generally…

Echocardiography Ultrasound artifacts The following artifacts are common in ultrasound imaging: The ultrasound image displays non existing structures. The ultrasound image does not display existing…

…ECG as increased amplitudes of the QRS complexes. The explanation is straightforward: myocardial muscle mass is increased and therefore it generates greater electrical potentials. However…

…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…

…Consequently, current guidelines recommend a 3 generation family history and consideration of genetic testing for all patients with non ischemic HFrEF. Toxic and infiltrative 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…

…larger than the right ventricle, the QRS complexes are dominated completely by the electrical currents generated by the left ventricle. This explains why leads V4…

…typically platelet rich and less occlusive, often presenting clinically as Non ST Elevation Myocardial Infarction (NSTEMI) rather than STEMI [4] . Calcified Nodules: A less common…

…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…

…30% of the myocardial cell volume, which enables the generation of such large amounts of ATP (Page et al). The mitochondrial density allows for complete…

…spreads outside of the His Purkinje system. The slow initial depolarization generates a delta wave on the ECG. Pre excitation will also cause a prolongation…