Catheter ablationCatheter ablation is a procedure that uses radio-frequency energy or other sources to terminate or modify a faulty electrical pathway from sections of the heart of those who are prone to developing cardiac arrhythmias such as atrial fibrillation, atrial flutter and Wolff-Parkinson-White syndrome. If not controlled, such arrhythmias increase the risk of ventricular fibrillation and sudden cardiac arrest. The ablation procedure can be classified by energy source: radiofrequency ablation and cryoablation.
Left bundle branch blockLeft bundle branch block (LBBB) is a conduction abnormality in the heart that can be seen on an electrocardiogram (ECG). In this condition, activation of the left ventricle of the heart is delayed, which causes the left ventricle to contract later than the right ventricle. Among the causes of LBBB are: Aortic stenosis Dilated cardiomyopathy Acute myocardial infarction Extensive coronary artery disease Primary disease of the cardiac electrical conduction system Long standing hypertension leading to aortic root dilatation and subsequent aortic regurgitation Lyme disease Slow or absent conduction through the left bundle branch means that it takes longer than normal for the left ventricle to fully depolarise.
Holiday heart syndromeHoliday heart syndrome, also known as alcohol-induced atrial arrhythmias, is a syndrome defined by an irregular heartbeat associated with high levels of ethanol consumption. Holiday heart syndrome was discovered in 1978 when Philip Ettinger discovered the connection between arrythmia and alcohol consumption. It received its common name as it is associated with the binge drinking common during the holidays. It is unclear how common this syndrome is. 5-10% of cases of atrial fibrillation may be related to this condition, but it could be as high 63%.
Linear filterLinear filters process time-varying input signals to produce output signals, subject to the constraint of linearity. In most cases these linear filters are also time invariant (or shift invariant) in which case they can be analyzed exactly using LTI ("linear time-invariant") system theory revealing their transfer functions in the frequency domain and their impulse responses in the time domain. Real-time implementations of such linear signal processing filters in the time domain are inevitably causal, an additional constraint on their transfer functions.
Cardiac monitoringCardiac monitoring generally refers to continuous or intermittent monitoring of heart activity to assess a patient's condition relative to their cardiac rhythm. Cardiac monitoring is usually carried out using electrocardiography, which is a noninvasive process that records the heart's electrical activity and displays it in an electrocardiogram. It is different from hemodynamic monitoring, which monitors the pressure and flow of blood within the cardiovascular system. The two may be performed simultaneously on critical heart patients.
Filter (signal processing)In signal processing, a filter is a device or process that removes some unwanted components or features from a signal. Filtering is a class of signal processing, the defining feature of filters being the complete or partial suppression of some aspect of the signal. Most often, this means removing some frequencies or frequency bands. However, filters do not exclusively act in the frequency domain; especially in the field of many other targets for filtering exist.
Cardiac cycleThe cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole. After emptying, the heart relaxes and expands to receive another influx of blood returning from the lungs and other systems of the body, before again contracting to pump blood to the lungs and those systems.
Chebyshev filterChebyshev filters are analog or digital filters that have a steeper roll-off than Butterworth filters, and have either passband ripple (type I) or stopband ripple (type II). Chebyshev filters have the property that they minimize the error between the idealized and the actual filter characteristic over the operating frequency range of the filter, but they achieve this with ripples in the passband. This type of filter is named after Pafnuty Chebyshev because its mathematical characteristics are derived from Chebyshev polynomials.
First-degree atrioventricular blockFirst-degree atrioventricular block (AV block) is a disease of the electrical conduction system of the heart in which electrical impulses conduct from the cardiac atria to the ventricles through the atrioventricular node (AV node) more slowly than normal. First degree AV block does not generally cause any symptoms, but may progress to more severe forms of heart block such as second- and third-degree atrioventricular block. It is diagnosed using an electrocardiogram, and is defined as a PR interval greater than 200 milliseconds.
Instantaneous phase and frequencyInstantaneous phase and frequency are important concepts in signal processing that occur in the context of the representation and analysis of time-varying functions. The instantaneous phase (also known as local phase or simply phase) of a complex-valued function s(t), is the real-valued function: where arg is the complex argument function. The instantaneous frequency is the temporal rate of change of the instantaneous phase. And for a real-valued function s(t), it is determined from the function's analytic representation, sa(t): where represents the Hilbert transform of s(t).
Time–frequency analysisIn signal processing, time–frequency analysis comprises those techniques that study a signal in both the time and frequency domains simultaneously, using various time–frequency representations. Rather than viewing a 1-dimensional signal (a function, real or complex-valued, whose domain is the real line) and some transform (another function whose domain is the real line, obtained from the original via some transform), time–frequency analysis studies a two-dimensional signal – a function whose domain is the two-dimensional real plane, obtained from the signal via a time–frequency transform.
Cardiac examinationIn medicine, the cardiac examination, also precordial exam, is performed as part of a physical examination, or when a patient presents with chest pain suggestive of a cardiovascular pathology. It would typically be modified depending on the indication and integrated with other examinations especially the respiratory examination. Like all medical examinations, the cardiac examination follows the standard structure of inspection, palpation and auscultation.
