Heart rate variability ( HRV ) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the variation in the beat-to-beat interval.
111-878: [REDACTED] Look up hrv in Wiktionary, the free dictionary. HRV may refer to: Medicine [ edit ] Heart rate variability Holmes' ribgrass virus Human rhinovirus Companies, groups and organizations [ edit ] Harness Racing Victoria , statutory body Holden Racing Team , motorsports team AirInter1 (ICAO airline code: HRV ), see List of defunct airlines of Chad Sahara Aero Services (ICAO airline code: HRV ), see List of defunct airlines of Chad Other uses [ edit ] Heat recovery ventilation Croatia (ISO 3166-1 alpha-3 code: HRV ; Croatian: Republika Hrvatska ) Croatian language (ISO 639-2 and ISO 639-3 codes hrv ; Croatian: hrvatski ) Honda HR-V ,
222-411: A blood test for biomarkers (the cardiac protein troponin ). When there is evidence of an MI, it may be classified as an ST elevation myocardial infarction (STEMI) or Non-ST elevation myocardial infarction (NSTEMI) based on the results of an ECG . The phrase "heart attack" is often used non-specifically to refer to myocardial infarction. An MI is different from—but can cause— cardiac arrest , where
333-475: A coronary artery caused by a rupture of an atherosclerotic plaque is usually the underlying mechanism of an MI. MIs are less commonly caused by coronary artery spasms , which may be due to cocaine , significant emotional stress (often known as Takotsubo syndrome or broken heart syndrome ) and extreme cold, among others. Many tests are helpful to help with diagnosis, including electrocardiograms (ECGs), blood tests and coronary angiography . An ECG, which
444-427: A HRV(HR) function with unprecedented precision: it can be described by two descending exponential components for healthy individuals, in general. Time domain methods are preferred to frequency domain methods when short-term recordings are investigated. This is due to the fact that the recording should be at least 10 times the wavelength of the lowest frequency bound of interest. Thus, recording of approximately 1 minute
555-474: A benefit of 15 to 45%. Physical activity can reduce the risk of cardiovascular disease, and people at risk are advised to engage in 150 minutes of moderate or 75 minutes of vigorous intensity aerobic exercise a week. Keeping a healthy weight, drinking alcohol within the recommended limits, and quitting smoking reduce the risk of cardiovascular disease. Substituting unsaturated fats such as olive oil and rapeseed oil instead of saturated fats may reduce
666-613: A cholinergically induced reduction of norepinephrine released in response to sympathetic activity, and a cholinergic attenuation of the response to an adrenergic stimulus. The RR interval variations present during resting conditions represent beat-by-beat variations in cardiac autonomic inputs. However, efferent vagal (parasympathetic) activity is a major contributor to the HF component, as seen in clinical and experimental observations of autonomic maneuvers such as electrical vagal stimulation, muscarinic receptor blockade, and vagotomy. More problematic
777-428: A common, and sometimes the only symptom, occurring when damage to the heart limits the output of the left ventricle , with breathlessness arising either from low oxygen in the blood or pulmonary edema . Other less common symptoms include weakness, light-headedness , palpitations , and abnormalities in heart rate or blood pressure . These symptoms are likely induced by a massive surge of catecholamines from
888-419: A continuum of emotion. The neurovisceral integration model describes how the prefrontal cortex regulates activity in limbic structures which act to suppress parasympathetic nervous system (PSNS) activity and activate sympathetic nervous system (SNS) circuits. Variation in the output of these two branches of the autonomic system produces HRV and activity in the prefrontal cortex can hence modulate HRV. HRV
999-485: A decrease in vagal activity directed to the heart. HRV in patients surviving an acute MI reveal a reduction in total and in the individual power of spectral components. The presence of an alteration in neural control is also reflected in a blunting of day-night variations of RR interval. In post-MI patients with a very depressed HRV, most of the residual energy is distributed in the VLF frequency range below 0.03 Hz, with only
1110-610: A drastic reduction in HRV, an LF component could not be detected despite the clinical signs of sympathetic activation. This reflects that, as stated above, the LF may not accurately reflect cardiac sympathetic tone. Liver cirrhosis is associated with decreased HRV. Decreased HRV in patients with cirrhosis has a prognostic value and predicts mortality. Loss of HRV is also associated with higher plasma pro-inflammatory cytokine levels and impaired neurocognitive function in this patient population. HRV
1221-480: A late consequence of Kawasaki disease . Calcium deposits in the coronary arteries can be detected with CT scans . Calcium seen in coronary arteries can provide predictive information beyond that of classical risk factors. High blood levels of the amino acid homocysteine is associated with premature atherosclerosis; whether elevated homocysteine in the normal range is causal is controversial. In people without evident coronary artery disease , possible causes for
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#17327986945281332-469: A measure of vagal tone. Myocardial infarction A myocardial infarction ( MI ), commonly known as a heart attack , occurs when blood flow decreases or stops in one of the coronary arteries of the heart , causing infarction (tissue death) to the heart muscle . The most common symptom is retrosternal chest pain or discomfort that classically radiates to the left shoulder, arm, or jaw. The pain may occasionally feel like heartburn . This
1443-431: A myocardial infarction before age 55 years, or a female first-degree relative (mother, sister) less than age 65 increases a person's risk of MI. Genome-wide association studies have found 27 genetic variants that are associated with an increased risk of myocardial infarction. The strongest association of MI has been found with chromosome 9 on the short arm p at locus 21, which contains genes CDKN2A and 2B, although
1554-463: A myocardial infarction increases with older age, low physical activity, and low socioeconomic status . Heart attacks appear to occur more commonly in the morning hours, especially between 6AM and noon. Evidence suggests that heart attacks are at least three times more likely to occur in the morning than in the late evening. Shift work is also associated with a higher risk of MI. One analysis has found an increase in heart attacks immediately following
1665-406: A myocardial infarction. Spasm of coronary arteries, such as Prinzmetal's angina may cause blockage. If impaired blood flow to the heart lasts long enough, it triggers a process called the ischemic cascade ; the heart cells in the territory of the blocked coronary artery die ( infarction ), chiefly through necrosis , and do not grow back. A collagen scar forms in their place. When an artery
1776-543: A myocardial infarction. The flow of blood can be imaged, and contrast dyes may be given to improve image. Other scans using radioactive contrast include SPECT CT-scans using thallium , sestamibi ( MIBI scans ) or tetrofosmin ; or a PET scan using Fludeoxyglucose or rubidium-82 . These nuclear medicine scans can visualize the perfusion of heart muscle. SPECT may also be used to determine viability of tissue, and whether areas of ischemia are inducible. Medical societies and professional guidelines recommend that
1887-637: A person localizes the chest pain by clenching one or both fists over their sternum , has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor positive predictive value . Typically, chest pain because of ischemia, be it unstable angina or myocardial infarction, lessens with the use of nitroglycerin , but nitroglycerin may also relieve chest pain arising from non-cardiac causes. Chest pain may be accompanied by sweating , nausea or vomiting, and fainting , and these symptoms may also occur without any pain at all. Dizziness or lightheadedness
1998-407: A previous heart attack is also suggestive. The pain associated with MI is usually diffuse, does not change with position, and lasts for more than 20 minutes. It might be described as pressure, tightness, knifelike, tearing, burning sensation (all these are also manifested during other diseases). It could be felt as an unexplained anxiety, and pain might be absent altogether. Levine's sign , in which
2109-399: A relation between changes in HRV and the extent of left ventricular dysfunction was reported. In fact, whereas the reduction in time domain measures of HRV seemed to parallel the severity of the disease, the relationship between spectral components and indices of ventricular dysfunction appears to be more complex. In particular, in most patients with a very advanced phase of the disease and with
2220-560: A rise in biomarkers, a rise in the ST segment , changes in the shape or flipping of T waves , new Q waves , or a new left bundle branch block can be used to diagnose an AMI. In addition, ST elevation can be used to diagnose an ST segment myocardial infarction (STEMI). A rise must be new in V2 and V3 ≥2 mm (0,2 mV) for males or ≥1.5 mm (0.15 mV) for females or ≥1 mm (0.1 mV) in two other adjacent chest or limb leads . ST elevation
2331-501: A role in the development of electrical instability. HRV is also depressed in SCD survivors, who are at high risk for subsequent episodes. HRV is markedly decreased prior to both fatal and non-fatal arrhythmias . HRV correlates with the progression of disease and outcome of cancer patients, according to a systematic review of published studies. Patients in the early stages of cancer have a significantly higher HRV when compared to patients in
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#17327986945282442-409: A series of leads placed on a person's chest that measure electrical activity associated with contraction of the heart muscle. The taking of an ECG is an important part of the workup of an AMI, and ECGs are often not just taken once but may be repeated over minutes to hours, or in response to changes in signs or symptoms. ECG readouts produce a waveform with different labeled features. In addition to
2553-406: A significant effect on blood cholesterol and thus recommendations about its consumption may not be needed. Trans fats do appear to increase risk. Acute and prolonged intake of high quantities of alcoholic drinks (3–4 or more daily) increases the risk of a heart attack. Family history of ischemic heart disease or MI, particularly if one has a male first-degree relative (father, brother) who had
2664-511: A single high-intensity peak (for example caused by an arrhythmic heart beat), the concept of the 'instantaneous Amplitude' has been introduced, which is based on the Hilbert transform of the RR data. A newly used HRV index, which depends on the wavelet entropy measures, is an alternative choice. The wavelet entropy measures are calculated using a three-step procedure defined in the literature. First,
2775-502: A small number of samples on which the signal is supposed to maintain stationarity. The basic disadvantage of parametric methods is the need of verification of the suitability of the chosen model and of its complexity (that is, the order of the model). In addition to classical FFT-based methods used for the calculation of frequency parameters, a more appropriate PSD estimation method is the Lomb–Scargle periodogram . Analysis has shown that
2886-441: A small respiration-related variations. In neuropathy associated with diabetes mellitus characterized by alteration in small nerve fibers, a reduction in time domain parameters of HRV seems not only to carry negative prognostic value but also to precede the clinical expression of autonomic neuropathy. In diabetic patients without evidence of autonomic neuropathy, reduction of the absolute power of LF and HF during controlled conditions
2997-430: A sport utility vehicle HRV, a Rockwell scale of materials' hardness See also [ edit ] [REDACTED] Search for "hrv" on Misplaced Pages. All pages with titles beginning with HRV All pages with titles containing HRV All pages with titles beginning with Hrv Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
3108-628: A time-independent background inward current, causes diastolic depolarization. Conversely, the "If activation" hypothesis suggests that after action potential termination, If provides a slowly activating inward current predominating over decaying Ik, thus initiating slow diastolic depolarization. The sympathetic influence on heart rate is mediated by release of epinephrine and norepinephrine. Activation of β-adrenergic receptors results in cAMP-mediated phosphorylation of membrane proteins and increases in ICaL and in If
3219-478: A variety of robust and tested artifact management tools. These software programs also include some automated capability but it is important that a human review any automated artifact management and edit accordingly. The most widely used methods can be grouped under time-domain and frequency-domain. A joint European and American task-force described standards in HRV measurements in 1996. Other methods have been proposed, such as non-linear methods. These are based on
3330-601: Is a known risk factor, particularly high low-density lipoprotein , low high-density lipoprotein , and high triglycerides . Many risk factors for myocardial infarction are potentially modifiable, with the most important being tobacco smoking (including secondhand smoke ). Smoking appears to be the cause of about 36% and obesity the cause of 20% of coronary artery disease . Lack of physical activity has been linked to 7–12% of cases. Less common causes include stress-related causes such as job stress , which accounts for about 3% of cases, and chronic high stress levels. There
3441-500: Is a point corresponding to the peak of the QRS complex of the ECG wave; and R–R is the interval between successive Rs), and "heart period variability". Measurement of the RR interval is used to derive heart rate variability. Methods used to detect beats include ECG, blood pressure, ballistocardiograms , and the pulse wave signal derived from a photoplethysmograph (PPG). ECG is considered
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3552-454: Is a recording of the heart's electrical activity, may confirm an ST elevation MI ( STEMI ), if ST elevation is present. Commonly used blood tests include troponin and less often creatine kinase MB . Treatment of an MI is time-critical. Aspirin is an appropriate immediate treatment for a suspected MI. Nitroglycerin or opioids may be used to help with chest pain; however, they do not improve overall outcomes. Supplemental oxygen
3663-806: Is also an important modifiable risk. Short-term exposure to air pollution such as carbon monoxide , nitrogen dioxide , and sulfur dioxide (but not ozone ) has been associated with MI and other acute cardiovascular events. For sudden cardiac deaths, every increment of 30 units in Pollutant Standards Index correlated with an 8% increased risk of out-of-hospital cardiac arrest on the day of exposure. Extremes of temperature are also associated. A number of acute and chronic infections including Chlamydophila pneumoniae , influenza , Helicobacter pylori , and Porphyromonas gingivalis among others have been linked to atherosclerosis and myocardial infarction. Myocardial infarction can also occur as
3774-404: Is also possible to represent long range correlations geometrically. Sequences of RR intervals have been found to have long-term correlations. However, one flaw with these analyses is their lack of goodness-of-fit statistics, i.e. values are derived that may or may not have adequate statistical rigor. Different types of correlations have been found during different sleep stages. A basic problem
3885-474: Is anatomic and physiological evidence for a polyvagal control of the heart. Variation in the beat-to-beat interval is a physiological phenomenon. The SA node receives several different inputs and the instantaneous heart rate or RR interval and its variation are the results of these inputs. Contribution of the respiratory rhythm to sinus arrhythmia in normal unanesthetized subjects during mechanical hyperventilation with positive pressure. The main inputs are
3996-499: Is associated with infarction, and may be preceded by changes indicating ischemia, such as ST depression or inversion of the T waves. Abnormalities can help differentiate the location of an infarct, based on the leads that are affected by changes. Early STEMIs may be preceded by peaked T waves. Other ECG abnormalities relating to complications of acute myocardial infarctions may also be evident, such as atrial or ventricular fibrillation . Noninvasive imaging plays an important role in
4107-479: Is assumed to be of sympathetic origin. In addition, a correlation between respiratory rate and the HF component of HRV observed in some transplanted patients also indicates that a nonneural mechanism may generate a respiration-related rhythmic oscillation. A reduced HRV has been observed consistently in patients with cardiac failure. In this condition characterized by signs of sympathetic activation such as faster heart rates and high levels of circulating catecholamines,
4218-517: Is blocked, cells lack oxygen , needed to produce ATP in mitochondria . ATP is required for the maintenance of electrolyte balance, particularly through the Na/K ATPase . This leads to an ischemic cascade of intracellular changes, necrosis and apoptosis of affected cells. Cells in the area with the worst blood supply, just below the inner surface of the heart ( endocardium ), are most susceptible to damage. Ischemia first affects this region,
4329-433: Is common and occurs due to reduction in oxygen and blood to the brain. In females, the most common symptoms of myocardial infarction include shortness of breath, weakness, and fatigue . Females are more likely to have unusual or unexplained tiredness and nausea or vomiting as symptoms. Females having heart attacks are more likely to have palpitations, back pain, labored breath, vomiting, and left arm pain than males, although
4440-566: Is decreased in patients with sepsis. Loss of HRV has both diagnostic and prognostic value in neonates with sepsis. The pathophysiology of decreased HRV in sepsis is not well understood but there is experimental evidence to show that partial uncoupling of cardiac pacemaker cells from autonomic neural control may play a role in decreased HRV during acute systemic inflammation. (Decreased HRV is generally lower in inflammatory conditions ). Patients with chronic complete high cervical spinal cord lesions have intact efferent vagal neural pathways directed to
4551-428: Is elevated by negative news in persons who react more strongly to negative news than to positive news. When completing a task, HRV is subject to change, especially when people need to regulate their emotions. Most importantly, individual differences are related to the ability to regulate emotions. Previous research has suggested that a large part of the attention regulation is due to the default inhibitory properties of
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4662-497: Is known about the physiological inputs of the low frequency (LF) activity (0.04 to 0.15 Hz). Though previously thought to reflect SNS activity, it is now widely accepted that it reflects a mixture of both the SNS and PSNS. There are two primary fluctuations: Errors in the location of the instantaneous heart beat will result in errors in the calculation of the HRV. HRV is highly sensitive to artifact and errors in as low as even 2% of
4773-403: Is mediated via release of acetylcholine by the vagus nerve. Muscarinic acetylcholine receptors respond to this release mostly by an increase in cell membrane K+ conductance. Acetylcholine also inhibits the hyperpolarization-activated "pacemaker" current. The "Ik decay" hypothesis proposes that pacemaker depolarization results from slow deactivation of the delayed rectifier current, Ik, which, due to
4884-452: Is needed to assess the HF components of HRV (i.e., a lowest bound of 0.15 Hz is a cycle of 6.6 seconds and so 10 cycles require ~60 seconds), while more than 4 minutes are needed to address the LF component (with a lower bound of 0.04 Hz). Although time domain methods, especially the SDNN and RMSSD methods, can be used to investigate recordings of long durations, a substantial part of
4995-493: Is negatively affected by lower HRV and positively affected by higher levels of HRV. Most importantly, resting-state HRV was found to be a significant predictor of cognitive functions such as decision making. HRV, accompanied by a psychological state such as anxiety, has been found to lead to poor decisions. For example, a group of researchers found that low HRV was an index of higher uncertainty leading to poor decision-making skills, especially those with higher levels of anxiety. HRV
5106-477: Is not the only cause of myocardial infarction, but it may exacerbate or contribute to other causes. A myocardial infarction may result from a heart with a limited blood supply subject to increased oxygen demands, such as in fever, a fast heart rate , hyperthyroidism , too few red blood cells in the bloodstream , or low blood pressure . Damage or failure of procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass grafts (CABG) may cause
5217-430: Is one of the most common symptoms of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper abdomen . The pain most suggestive of an acute MI, with the highest likelihood ratio , is pain radiating to the right arm and shoulder. Similarly, chest pain similar to
5328-414: Is recommended in those with low oxygen levels or shortness of breath. In a STEMI, treatments attempt to restore blood flow to the heart and include percutaneous coronary intervention (PCI), where the arteries are pushed open and may be stented , or thrombolysis , where the blockage is removed using medications. People who have a non-ST elevation myocardial infarction ( NSTEMI ) are often managed with
5439-453: Is reduced whilst the low-frequency (LF) component is elevated. Furthermore, PTSD patients demonstrated no LF or HF reactivity to recalling a traumatic event. Statistical quantitative differences have also been found among healthy, depressed, and psychotic people. The neurovisceral integration is a model of HRV that views the central autonomic network as the decision maker of cognitive, behavioral and physiological regulation as they pertain to
5550-537: Is reported to be an index of the influence of both the parasympathetic and the sympathetic nervous system. For example, high HRV is shown to reflect proper emotion regulation, decision-making, and attention, and low HRV reflects the opposite. The parasympathetic nervous system works to decrease the heart rate, while the SNS works to increase the heart rate. For example, someone with high HRV may reflect increased parasympathetic activity, and someone with low HRV may reflect increased sympathetic activity. Emotions stem from
5661-412: Is still unable to be distributed to the affected myocardium despite clearing the occlusion—also contributes to myocardial injury. Topical endothelial swelling is one of many factors contributing to this phenomenon. A myocardial infarction, according to current consensus, is defined by elevated cardiac biomarkers with a rising or falling trend and at least one of the following: A myocardial infarction
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#17327986945285772-623: Is that all the parameters used to characterize HRV strongly depend on heart rate, but many articles have not adjusted properly or at all for HR differences when comparing HRV in multiple circumstances. However, the exact HRV(HR) relationship is still a matter of debate. For time domain parameters (RMSSD, SDNN, etc.) the results imply that, if there exists a universal function, it should be either exponential or hyperbolic in nature. The evaluation procedures used to determine HRV(HR) function have not allowed to decide between these options, so far. A new evaluation method has recently allowed to determine
5883-586: Is the Poincaré plot . Each data point represents a pair of successive beats, the x-axis is the current RR interval, while the y-axis is the previous RR interval. HRV is quantified by fitting mathematically defined geometric shapes to the data. Other methods used are the correlation dimension , symbolic dynamics, nonlinear predictability, pointwise correlation dimension, approximate entropy, sample entropy , multiscale entropy analysis, sample asymmetry and memory length (based on inverse statistical analysis). It
5994-789: Is the dangerous type of Acute coronary syndrome . Other symptoms may include shortness of breath , nausea , feeling faint , a cold sweat , feeling tired , and decreased level of consciousness . About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure , an irregular heartbeat , cardiogenic shock or cardiac arrest . Most MIs occur due to coronary artery disease . Risk factors include high blood pressure , smoking , diabetes , lack of exercise , obesity , high blood cholesterol , poor diet, and excessive alcohol intake . The complete blockage of
6105-411: Is the interpretation of the LF component, which was considered by some as a marker of sympathetic modulation (especially when expressed in normalized units) but is now known to include both sympathetic and vagal influences. For example, during sympathetic activation the resulting tachycardia is usually accompanied by a marked reduction in total power, whereas the reverse occurs during vagal activation. Thus
6216-457: Is usually clinically classified as an ST-elevation MI (STEMI) or a non-ST elevation MI (NSTEMI). These are based on ST elevation , a portion of a heartbeat graphically recorded on an ECG . STEMIs make up about 25–40% of myocardial infarctions. A more explicit classification system, based on international consensus in 2012, also exists. This classifies myocardial infarctions into five types: There are many different biomarkers used to determine
6327-445: Is varying evidence about the importance of saturated fat in the development of myocardial infarctions. Eating polyunsaturated fat instead of saturated fats has been shown in studies to be associated with a decreased risk of myocardial infarction, while other studies find little evidence that reducing dietary saturated fat or increasing polyunsaturated fat intake affects heart attack risk. Dietary cholesterol does not appear to have
6438-494: The baroreflex , thermoregulation , hormones , sleep–wake cycle , meals, physical activity, and stress . Decreased PSNS activity or increased SNS activity will result in reduced HRV. High frequency (HF) activity (0.15 to 0.40 Hz), especially, has been linked to PSNS activity. Activity in this range is associated with the respiratory sinus arrhythmia (RSA), a vagally mediated modulation of heart rate such that it increases during inspiration and decreases during expiration. Less
6549-661: The elderly , in those with diabetes mellitus and after heart transplantation . In people with diabetes, differences in pain threshold , autonomic neuropathy , and psychological factors have been cited as possible explanations for the lack of symptoms. In heart transplantation, the donor heart is not fully innervated by the nervous system of the recipient. The most prominent risk factors for myocardial infarction are older age, actively smoking , high blood pressure , diabetes mellitus , and total cholesterol and high-density lipoprotein levels. Many risk factors of myocardial infarction are shared with coronary artery disease ,
6660-480: The health impact assessment of regional and local plans and policies. Most guidelines recommend combining different preventive strategies. A 2015 Cochrane Review found some evidence that such an approach might help with blood pressure , body mass index and waist circumference . However, there was insufficient evidence to show an effect on mortality or actual cardio-vascular events. Statins , drugs that act to lower blood cholesterol, decrease
6771-522: The single nucleotide polymorphisms that are implicated are within a non-coding region. The majority of these variants are in regions that have not been previously implicated in coronary artery disease. The following genes have an association with MI: PCSK9 , SORT1 , MIA3 , WDR12 , MRAS , PHACTR1 , LPA , TCF21 , MTHFDSL , ZC3HC1 , CDKN2A , 2B , ABO , PDGF0 , APOA5 , MNF1ASM283 , COL4A1 , HHIPC1 , SMAD3 , ADAMTS7 , RAS1 , SMG6 , SNF8 , LDLR , SLC5A3 , MRPS6 , KCNE2 . The risk of having
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#17327986945286882-481: The subendocardial region, and tissue begins to die within 15–30 minutes of loss of blood supply. The dead tissue is surrounded by a zone of potentially reversible ischemia that progresses to become a full-thickness transmural infarct. The initial "wave" of infarction can take place over 3–4 hours. These changes are seen on gross pathology and cannot be predicted by the presence or absence of Q waves on an ECG. The position, size and extent of an infarct depends on
6993-452: The sympathetic and the parasympathetic nervous system (PSNS) and humoral factors . Respiration gives rise to waves in heart rate mediated primarily via the PSNS, and it is thought that the lag in the baroreceptor feedback loop may give rise to 10 second waves in heart rate (associated with Mayer waves of blood pressure), but this remains controversial. Factors that affect the input are
7104-551: The sympathetic nervous system , which occurs in response to pain and, where present, low blood pressure . Loss of consciousness can occur in myocardial infarctions due to inadequate blood flow to the brain and cardiogenic shock , and sudden death , frequently due to the development of ventricular fibrillation . When the brain was without oxygen for too long due to a myocardial infarction, coma and persistent vegetative state can occur. Cardiac arrest, and atypical symptoms such as palpitations , occur more frequently in females,
7215-506: The LS periodogram can produce a more accurate estimate of the PSD than FFT methods for typical RR data. Since the RR data is an unevenly sampled data, another advantage of the LS method is that in contrast to FFT-based methods it is able to be used without the need to resample and detrend the RR data. Alternatively, to avoid artefacts that are created when calculating the power of a signal that includes
7326-537: The United States. In the developed world, the risk of death in those who have had a STEMI is about 10%. Rates of MI for a given age have decreased globally between 1990 and 2010. In 2011, an MI was one of the top five most expensive conditions during inpatient hospitalizations in the US, with a cost of about $ 11.5 billion for 612,000 hospital stays. Myocardial infarction (MI) refers to tissue death ( infarction ) of
7437-401: The active response to an environmental threat, and the fluctuation between the connect and disconnect to an environmental threat. This theory, like others, decomposes heart rate variability based on frequency domain characteristics. However, it places more emphasis on respiratory sinus arrhythmia and its transmission by a hypothesized neural pathway distinct from other components of HRV. There
7548-432: The acute diagnostic algorithm; however, it can confirm a clinical suspicion of Chronic Coronary Syndrome when the patient's history, physical examination (including cardiac examination ) ECG, and cardiac biomarkers suggest coronary artery disease. Echocardiography , an ultrasound scan of the heart, is able to visualize the heart, its size, shape, and any abnormal motion of the heart walls as they beat that may indicate
7659-409: The affected artery, totality of the blockage, duration of the blockage, the presence of collateral blood vessels , oxygen demand, and success of interventional procedures. Tissue death and myocardial scarring alter the normal conduction pathways of the heart and weaken affected areas. The size and location put a person at risk of abnormal heart rhythms (arrhythmias) or heart block , aneurysm of
7770-512: The analytic quality of the series of NN intervals – need of reasonable number of NN intervals to generate the geometric pattern (in practice 20 min to 24 h) – not appropriate to assess short-term changes in HRV Frequency domain methods assign bands of frequency and then count the number of NN intervals that match each band. The bands are typically high frequency (HF) from 0.15 to 0.4 Hz, low frequency (LF) from 0.04 to 0.15 Hz, and
7881-434: The beat-to-beat or NN intervals, which are analysed to give variables such as: The series of NN intervals also can be converted into a geometric pattern such as: Geometric Measures HRV triangular index: integral of density distribution / maximum of density distribution maximum HRV triangular index = Number of all NN intervals / maximum number. Dependent on the length of the bin -> quote the bin size+ relative insensitive to
7992-647: The blood thinner heparin , with the additional use of PCI in those at high risk. In people with blockages of multiple coronary arteries and diabetes, coronary artery bypass surgery (CABG) may be recommended rather than angioplasty . After an MI, lifestyle modifications, along with long-term treatment with aspirin, beta blockers and statins , are typically recommended. Worldwide, about 15.9 million myocardial infarctions occurred in 2015. More than 3 million people had an ST elevation MI, and more than 4 million had an NSTEMI. STEMIs occur about twice as often in men as women. About one million people have an MI each year in
8103-424: The cases) and (2) the high processing speed. The advantages of parametric methods are (1) smoother spectral components that can be distinguished independent of preselected frequency bands, (2) easy postprocessing of the spectrum with an automatic calculation of low- and high-frequency power components with an easy identification of the central frequency of each component, and (3) an accurate estimation of PSD even on
8214-476: The data will result in unwanted biases in HRV calculations. To ensure accurate results therefore it is critical to manage artifact and RR errors appropriately prior to performing any HRV analyses. Robust management of artifacts, including RWave identification, interpolation and exclusion requires a high degree of care and precision. This can be very time-consuming in large studies with data recorded over long durations. Software packages are able to assist users with
8325-567: The definition of entropy given by Shannon. Given the complexity of the mechanisms regulating heart rate, it is reasonable to assume that applying HRV analysis based on methods of non-linear dynamics will yield valuable information. Although chaotic behavior has been assumed, more rigorous testing has shown that heart rate variability cannot be described as a low dimensional chaotic process. However, application of chaotic globals to HRV has been shown to predict diabetes status. The most commonly used non-linear method of analysing heart rate variability
8436-405: The diagnosis and characterisation of myocardial infarction. Tests such as chest X-rays can be used to explore and exclude alternate causes of a person's symptoms. Echocardiography may assist in modifying clinical suspicion of ongoing myocardial infarction in patients that can't be ruled out or ruled in following initial ECG and Troponin testing. Myocardial perfusion imaging has no role in
8547-616: The diagnostic accuracy of troponin testing is improving over time. One high-sensitivity cardiac troponin can rule out a heart attack as long as the ECG is normal. Other tests, such as CK-MB or myoglobin , are discouraged. CK-MB is not as specific as troponins for acute myocardial injury, and may be elevated with past cardiac surgery, inflammation or electrical cardioversion; it rises within 4–8 hours and returns to normal within 2–3 days. Copeptin may be useful to rule out MI rapidly when used along with troponin. Electrocardiograms (ECGs) are
8658-414: The elderly, those with diabetes, in people who have just had surgery, and in critically ill patients. "Silent" myocardial infarctions can happen without any symptoms at all. These cases can be discovered later on electrocardiograms , using blood enzyme tests, or at autopsy after a person has died. Such silent myocardial infarctions represent between 22 and 64% of all infarctions, and are more common in
8769-680: The gold standard for HRV measurement because it provides a direct reflection of cardiac electric activity. Reduced HRV has been shown to be a predictor of mortality after myocardial infarction although others have shown that the information in HRV relevant to acute myocardial infarction survival is fully contained in the mean heart rate . A range of other outcomes and conditions may also be associated with modified (usually lower) HRV, including congestive heart failure , diabetic neuropathy , post– cardiac-transplant depression, susceptibility to SIDS and poor survival in premature babies , as well as fatigue severity in chronic fatigue syndrome . On
8880-637: The greatest support is the Mediterranean diet . Vitamins and mineral supplements are of no proven benefit, and neither are plant stanols or sterols . Public health measures may also act at a population level to reduce the risk of myocardial infarction, for example by reducing unhealthy diets (excessive salt, saturated fat, and trans-fat) including food labeling and marketing requirements as well as requirements for catering and restaurants and stimulating physical activity. This may be part of regional cardiovascular disease prevention programs or through
8991-465: The heart is not contracting at all or so poorly that all vital organs cease to function, thus leading to death. It is also distinct from heart failure , in which the pumping action of the heart is impaired. However, an MI may lead to heart failure. Chest pain that may or may not radiate to other parts of the body is the most typical and significant symptom of myocardial infarction. It might be accompanied by other symptoms such as sweating. Chest pain
9102-410: The heart muscle ( myocardium ) caused by ischemia , the lack of oxygen delivery to myocardial tissue. It is a type of acute coronary syndrome , which describes a sudden or short-term change in symptoms related to blood flow to the heart. Unlike the other type of acute coronary syndrome, unstable angina , a myocardial infarction occurs when there is cell death , which can be estimated by measuring by
9213-441: The heart ventricles , inflammation of the heart wall following infarction, and rupture of the heart wall that can have catastrophic consequences. Injury to the myocardium also occurs during re-perfusion. This might manifest as ventricular arrhythmia. The re-perfusion injury is a consequence of the calcium and sodium uptake from the cardiac cells and the release of oxygen radicals during reperfusion. No-reflow phenomenon—when blood
9324-729: The heart, lungs , gastrointestinal tract , aorta , and other muscles, bones and nerves surrounding the chest. In addition to myocardial infarction, other causes include angina , insufficient blood supply ( ischemia ) to the heart muscles without evidence of cell death, gastroesophageal reflux disease ; pulmonary embolism , tumors of the lungs, pneumonia , rib fracture , costochondritis , heart failure and other musculoskeletal injuries. Rarer severe differential diagnoses include aortic dissection , esophageal rupture , tension pneumothorax , and pericardial effusion causing cardiac tamponade . The chest pain in an MI may mimic heartburn . Causes of sudden-onset breathlessness generally involve
9435-402: The incidence and mortality rates of myocardial infarctions. They are often recommended in those at an elevated risk of cardiovascular diseases. Aspirin has been studied extensively in people considered at increased risk of myocardial infarction. Based on numerous studies in different groups (e.g. people with or without diabetes), there does not appear to be a benefit strong enough to outweigh
9546-659: The later stages of cancer, suggesting disease severity influences HRV. Different ranges of HRV can be observed between cancer types. HRV alterations occur in healthy pregnancies as well as similar changes in pregnancies with gestational diabetes that include lower HRV mean values. Low RMSSD, thought to represent vagal tone, have been associated with major depression. Lower SDNN and elevated LF/HF were found in those with bipolar disorder, and in particular those characterized as having greater illness severity due to greater number of episodes, illness duration and whether there had been psychosis. Patients with PTSD also had lower HF,
9657-403: The long-term variability is day–night differences. Thus, long-term recordings analyzed by time domain methods should contain at least 18 hours of analyzable ECG data that include the whole night. Although cardiac automaticity is intrinsic to various pacemaker tissues, heart rate and rhythm are largely under the control of the autonomic nervous system. The parasympathetic influence on heart rate
9768-666: The lungs or heart – including pulmonary edema , pneumonia, allergic reactions and asthma , and pulmonary embolus, acute respiratory distress syndrome and metabolic acidosis . There are many different causes of fatigue, and myocardial infarction is not a common cause. There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as secondary prevention after an initial myocardial infarction, because of shared risk factors and an aim to reduce atherosclerosis affecting heart vessels. The influenza vaccine also appear to protect against myocardial infarction with
9879-610: The myocardial infarction are coronary spasm or coronary artery dissection . The most common cause of a myocardial infarction is the rupture of an atherosclerotic plaque on an artery supplying heart muscle. Plaques can become unstable, rupture, and additionally promote the formation of a blood clot that blocks the artery; this can occur in minutes. Blockage of an artery can lead to tissue death in tissue being supplied by that artery. Atherosclerotic plaques are often present for decades before they result in symptoms. The gradual buildup of cholesterol and fibrous tissue in plaques in
9990-624: The other hand, for patients having high blood pressure ( hypertension ), higher HRV is a risk factor for atrial fibrillation . There is interest in HRV in the field of psychophysiology . For example, HRV is related to emotional arousal. High-frequency (HF) activity has been found to decrease under conditions of acute time pressure and emotional strain and elevated anxiety state, presumably related to focused attention and motor inhibition. HRV has been shown to be reduced in individuals reporting to worry more. In individuals with post-traumatic stress disorder (PTSD), HRV and its HF component (see below)
10101-419: The physician confirm a person is at high risk for Chronic Coronary Syndrome before conducting diagnostic non-invasive imaging tests to make a diagnosis, as such tests are unlikely to change management and result in increased costs. Patients who have a normal ECG and who are able to exercise, for example, most likely do not merit routine imaging. There are many causes of chest pain , which can originate from
10212-438: The physiological modulation of the parasympathetic and sympathetic nervous system. The activity behind the prefrontal cortex and the parasympathetic and sympathetic nervous system can influence heart activity. However, people are not all affected the same. A systematic review of HRV and cognitive function suggested that resting HRV can predict individual differences in attentional performance. Furthermore, HRV has been able to index
10323-471: The plaque and act to stabilize it. A stable plaque may have a thick fibrous cap with calcification . If there is ongoing inflammation, the cap may be thin or ulcerate. Exposed to the pressure associated with blood flow, plaques, especially those with a thin lining, may rupture and trigger the formation of a blood clot (thrombus). The cholesterol crystals have been associated with plaque rupture through mechanical injury and inflammation. Atherosclerotic disease
10434-411: The power distribution across frequencies. One of the most commonly used PSD methods is the discrete Fourier transform . Methods for the calculation of PSD may be generally classified as nonparametric and parametric. In most instances, both methods provide comparable results. The advantages of the nonparametric methods are (1) the simplicity of the algorithm used ( fast Fourier transform [FFT] in most of
10545-494: The prefrontal cortex. Top-down processes from the prefrontal cortex provide parasympathetic influences, and if for some reason, those influences are active, attention can suffer. Researchers have suggested that HRV can index attention. It was found that groups with high anxiety and low HRV have poor attention. In line with this research, it has also been suggested that increased attention has been linked to high HRV and increased vagus nerve activity. The vagus nerve activity reflects
10656-487: The presence of cardiac muscle damage. Troponins , measured through a blood test, are considered to be the best, and are preferred because they have greater sensitivity and specificity for measuring injury to the heart muscle than other tests. A rise in troponin occurs within 2–3 hours of injury to the heart muscle, and peaks within 1–2 days. The level of the troponin, as well as a change over time, are useful in measuring and diagnosing or excluding myocardial infarctions, and
10767-512: The primary cause of myocardial infarction, with other risk factors including male sex, low levels of physical activity, a past family history , obesity , and alcohol use . Risk factors for myocardial disease are often included in risk factor stratification scores, such as the Framingham Risk Score . At any given age, men are more at risk than women for the development of cardiovascular disease. High levels of blood cholesterol
10878-490: The result is an acceleration of the slow diastolic depolarization. Under resting conditions, vagal tone prevails and variations in heart period are largely dependent on vagal modulation. The vagal and sympathetic activity constantly interact. Because the sinus node is rich in acetylcholinesterase, the effect of any vagal impulse is brief because the acetylcholine is rapidly hydrolyzed. Parasympathetic influences exceed sympathetic effects probably through two independent mechanisms:
10989-486: The risk of myocardial infarction, although there is not universal agreement. Dietary modifications are recommended by some national authorities, with recommendations including increasing the intake of wholegrain starch, reducing sugar intake (particularly of refined sugar), consuming five portions of fruit and vegetables daily, consuming two or more portions of fish per week, and consuming 4–5 portions of unsalted nuts , seeds , or legumes per week. The dietary pattern with
11100-425: The role of attention and performance, supporting high HRV as a biomarker of increased attention and performance. Decision-making skills are found to be indexed by HRV in several studies. Previous research has suggested that both emotion and attention are linked to decision making; for example, poor decision making is linked to the inability to regulate or control emotions and attention and vice versa. Decision making
11211-491: The sinus node. However, an LF component can be detected in HRV and arterial pressure variabilities of some tetraplegic patients. Thus, the LF component of HRV in those without intact sympathetic inputs to the heart represent vagal modulation. Victims of sudden cardiac death have been found to have had lower HRV than healthy individuals. HRV can be observed to be depressed prior to the development of SCD, which raises questions about whether or not altered autonomic function plays
11322-475: The spectral components change in the same direction and do not indicate that LF faithfully reflects sympathetic effects. HRV measures fluctuations in autonomic inputs to the heart rather than the mean level of autonomic inputs. Thus, both withdrawal and saturatingly high levels of autonomic input to the heart can lead to diminished HRV. A reduction of HRV has been reported in several cardiovascular and noncardiovascular diseases. Depressed HRV after MI may reflect
11433-399: The start of daylight saving time . Women who use combined oral contraceptive pills have a modestly increased risk of myocardial infarction, especially in the presence of other risk factors. The use of non-steroidal anti inflammatory drugs (NSAIDs), even for as short as a week, increases risk. Endometriosis in women under the age of 40 is an identified risk factor. Air pollution
11544-400: The studies showing these differences had high variability. Females are less likely to report chest pain during a heart attack and more likely to report nausea, jaw pain, neck pain, cough, and fatigue, although these findings are inconsistent across studies. Females with heart attacks also had more indigestion, dizziness , loss of appetite , and loss of consciousness. Shortness of breath is
11655-669: The time and impact of a situation on a person. The ability to regulate emotions is essential for social environments and well-being. HRV has provided a window to the physiological components associated with emotional regulation. HRV has been shown to reflect emotional regulation at two different levels, while resting and while completing a task. Research suggests that a person with higher HRV while resting can provide more appropriate emotional responses compared to those that have low HRV at rest. Empirical research found that HRV can reflect better emotional regulation by those with higher resting HRV, particularly with negative emotions . However, HRV
11766-575: The title HRV . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=HRV&oldid=1258799713 " Category : Disambiguation pages Hidden categories: Articles containing Croatian-language text Short description is different from Wikidata All article disambiguation pages All disambiguation pages Heart rate variability Other terms used include "cycle length variability", "R–R variability" (where R
11877-552: The very low frequency (VLF) from 0.0033 to 0.04 Hz. HF power reflects stimulation by the parasympathetic nervous system (PNS), whereas LF power reflects stimulation by both the sympathetic nervous system (SNS) and the PNS. VLF power is associated with thermoregulation , the renin–angiotensin system . and peripheral vasomotor activity. Several methods of analysis are available. Power spectral density (PSD), using parametric or nonparametric methods, provides basic information on
11988-529: The wall of the coronary arteries or other arteries, typically over decades, is termed atherosclerosis . Atherosclerosis is characterized by progressive inflammation of the walls of the arteries. Inflammatory cells, particularly macrophages , move into affected arterial walls. Over time, they become laden with cholesterol products, particularly LDL , and become foam cells . A cholesterol core forms as foam cells die. In response to growth factors secreted by macrophages, smooth muscle and other cells move into
12099-485: The wavelet packet algorithm is implemented using the Daubechies 4 (DB4) function as the mother wavelet with a scale of 7. Once the wavelet coefficients are obtained, the energy for each coefficient are calculated as described in the literature. After calculating the normalized values of wavelet energies, which represent the relative wavelet energy (or the probability distribution), the wavelet entropies are obtained using
12210-438: Was also reported. Similarly, diabetic patients can be differentiated from normal controls on the basis of reduction in HRV. A very reduced HRV with no definite spectral components has been reported in patients with a recent heart transplant. The appearance of discrete spectral components in a few patients is considered to reflect cardiac reinnervation. This reinnervation may occur as early as 1 to 2 years after transplantation and
12321-538: Was also used to assess decision-making skills in a high-risk game and was found to be an index higher sympathetic activation (lower HRV) when making decisions involving risk. HRV can index psychological concepts, such as the ones outlined above, to assess the demand for the situations that people experience. The polyvagal theory is another way to describe the pathways in the autonomic nervous system that mediate HRV. The polyvagal theory highlights three main ordinal processes, inactive response to an environmental threat,
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