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| {{SI}} | | {{Premature ventricular contraction}} |
| {{CMG}}
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| {{SK}} PVC; PVCs; premature ventricular contractions; premature ventricular complex; premature ventricular complexes; premature ventricular beat; premature ventricular beats; PVB; PVBs; ventricular premature beat; ventricular premature beats; VPB; VPBs; ventricular premature complex; ventricular premature complexes; ventricular premature contraction; ventricular premature contractions; VPC; VPCs; extrasystole, ventricular;
| | '''For patient information, click [[Premature ventricular contraction (patient information)|here]]''' |
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| ==Overview==
| | {{CMG}}; {{AE}}{{Radwa}}{{Homa}}{{M.P}} |
| '''Premature ventricular contraction''' is a form of irregular [[heart rate|heartbeat]] in which the [[ventricle (heart)|ventricle]] contracts prematurely. This results in a "skipped beat" followed by a stronger beat. Individuals may report a feeling that their heart "stops" after a premature ventricular contraction.
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| ==Pathophysiology==
| | {{SK}} [[Premature ventricular beat]]; [[premature ventricular beats]]; [[premature ventricular complex]]; [[premature ventricular complexes]]; premature ventricular contraction; [[premature ventricular contractions]]; [[PVB]]; [[PVBs]]; [[PVC]]; [[PVCs]]; [[VEA]]; [[VEB]]; [[VEBs]]; [[VES]]; [[ventricular ectopic activity]]; [[ventricular ectopic beat]]; [[ventricular ectopic beats]]; [[ventricular extrasystole]]; [[ventricular premature beat]]; [[ventricular premature beats]]; [[ventricular premature complex]]; [[ventricular premature complexes]]; [[ventricular premature contraction]]; [[ventricular premature contractions]]; [[VPB]]; [[VPBs]]; [[VPC]]; [[VPCs]] |
| The depolarization of the heart muscle begins in the ventricle instead of the usual place, the [[sinus node]].
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| ==Causes== | | ==[[Premature ventricular contraction overview|Overview]]== |
| ===Common Causes===
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| Some possible causes of PVC in adults include the use of [[cocaine]], [[amphetamines]], [[Alcoholic beverage|alcohol]], and [[tobacco]]. Medicines including [[digoxin]], [[sympathomimetics]], [[tricyclic antidepressant]]s, and [[aminophylline]] have also been known to trigger attacks of PVC. Increased levels of [[adrenaline]] are thought to play a role, often caused by [[caffeine]], exercise or anxiety.
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| <ref>[http://www.mayoclinic.com/health/premature-ventricular-contractions/DS00949/DSECTION=3=Citation Premature ventricular contractions]. MayoClinic.com</ref>
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| Heart conditions or a previous history of [[myocardial infarction|heart attack]], [[ischemia]], [[myocarditis]], [[Dilated cardiomyopathy|dilated]] or [[hypertrophic cardiomyopathy]], myocardial [[contusion]], [[atrial fibrillation]] and [[mitral valve prolapse]] may cause PVC. Patients with [[hypomagnesemia]], [[hypokalemia]], and [[hypercalcemia]] may also present with PVC.
| | ==[[Premature ventricular contraction historical perspective|Historical Perspective]]== |
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| PVCs in young children are thought to be associated with developmental factors of the [[autonomic nervous system]]. In older children, sympathomimetic drugs, such as [[Common cold|cold]] or [[asthma]] medication may cause PVCs, along with mild cases of viral [[myocarditis]].
| | ==[[Premature ventricular contraction classification|Classification]]== |
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| ===Causes in Alphabetical Order=== | | ==[[Premature ventricular contraction pathophysiology|Pathophysiology]]== |
| * [[Ddx:Acidosis|Acidosis]]
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| * [[Addison's Disease]]
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| * After [[Right heart catheterization|heart catheterization]]
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| * After [[heart surgery]], [[trauma]]
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| * [[Amyloidosis]]
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| * [[Brucellosis]]
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| * [[Cardiac Valve Disease]]
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| * [[Cirrhosis]]
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| * [[Congenital Heart Disease]]
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| * [[Cor Pulmonale]]
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| * [[Diabetes Mellitus]]
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| * [[Diaphragmatic eventration]]
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| * [[Diptheria]]
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| * Drugs, [[toxin]]s
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| * [[Electrocution]]
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| * [[Electrolyte imbalance]]
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| * [[Emotional stress]]
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| * [[Glycogen storage disease]]
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| * [[Heart failure]]
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| * [[Hemochromatosis]]
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| * [[Ddx:Hypercalcemia|Hypercalcemia]]
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| * [[Ddx:Hyperkalemia|Hyperkalemia]]
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| * [[Hypertension]]
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| * [[Ddx:Hyperthyroidism|Hyperthyroidism]]
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| * In healthy persons
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| * [[Intoxication]]
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| * [[Long QT syndrome]]
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| * [[Meteorism]]
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| * [[Perimyocarditis]]
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| * [[Pheochromocytoma]]
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| * [[Protein deficiency]]
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| * [[Pulmonary Embolism]]
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| * [[Rheumatic Fever]]
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| * [[Scarlet Fever]]
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| * [[Scleroderma]]
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| * [[STEMI]]
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| * [[Vitamin B12 Deficiency]]
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| ==Pathophysiology== | | ==[[Premature ventricular contraction causes|Causes]]== |
| Aberrant ventricular conduction is:
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| * A transient form of abnormal IVCD
| | ==[[Premature ventricular contraction differential diagnosis|Differentiating Premature ventricular contraction from other Disorders]]== |
| * Occurs when there is unequal refractoriness of the two bundles
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| * The right bundle has a longer action potential duration, and is more vulnerable to conduction delay or failure.
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| * The refractory period is affected by the preceding cycle length.
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| * The refractory period is longer when there is a long preceding RR interval
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| * aberrant ventricular conduction is favored when a premature supraventricular impulse comes after a long preceding RR interval ([[Ashman phenomenon]]).
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| * If the underlying rhythm is sinus in origin, and if the abnormal [[QRS]] is preceded by a premature [[P wave]], then the ectopic beat is likely to be supraventricular in origin.
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| * The absence of a fully compensatory pause further supports this diagnosis.
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| * If a retrograde P wave is identifiable after the [[QRS]] complex and the RP interval is less than 0.11 second, the premature beat is likely to have originated from the AV junction, since the RP interval is too short for VA conduction (unless an accessory pathway is present).
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| * A long RP interval of 0.20 seconds or longer is suggestive but not diagnostic of a PVC, since the retrograde conduction time of a junctional beat is less likely to exceed this duration.
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| * The beat is more likely to be due to aberrancy if the initial forces are similar to those of the sinus beat and if it has an RSR' configuration in lead V1.
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| *: If the [[QRS]] complexes in all the precordial leads are positive or all negative,then a PVC is more likely.
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| *: Diagnosis of PVCs in the presence of atrial fibrillation:
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| *:* Absence of [[P wave]]s and the irregularity of the rhythm are the handicaps.
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| *:* A constant coupling time is suggestive of PVCs.
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| *:* [[Ashman phenomenon]]. Keep in mind that a long cycle length also favors the precipitation of a PVC, therefore this sign is helpful but not diagnostic of aberrancy.
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| *:* PVC is favored if the abnormal complex terminates a short-long cycle.
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| == Clinical Correlation == | | ==[[Premature ventricular contraction epidemiology and demographics|Epidemiology and Demographics]]== |
| # Healthy patients
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| #* The most common arrhythmia in patients with and without CAD.
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| #* Less common in infants and children, more common in the elderly.
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| #* Usually originate from the RV.
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| #* In normal patients, they may be either precipitated or suppressed by exercise.
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| #* No relationship to coffee or smoking has been established.
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| #* Frequency decreases with sleep.
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| # Coronary artery disease
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| #* Routine ECGs demonstrate PVCs in 10% of patients with CAD.
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| #* Incidence inreases to 60 to 88% when the monitoring is increased to 12 to 24 hours.
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| #* The frequency of complex VEA increases with increasing numbers of vessels involved. (40% with one, 53% with two, and 78% with three vessels involved has VEA).
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| #* Patients with CAD are more prone to develop VEA with exercise (incidence 4 times higher than age matched controls).
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| #* Reported incidence in acute MI varies, but is near 100%.
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| #* After the initial 6 hours, the frequency decreases.
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| #* Persistence of VEA is associated with larger infarct size.
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| #* In one study, patients with EFs of greater than 50% had no persistent VEA, and patients with EFs of less than 30% had frequent PVCs.
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| # Other Organic Heart Diseases:
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| #* occur on routine EKG in 1/3rd of patients.
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| #* 12% of patients with congested cardiomyopathy have PVC on routine tracings.
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| #* 1.6% of patients with IHSS have PVCs on routine EKG.
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| # Drugs:
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| #* PVCs are the most common arrhythmia in patients with digoxin toxicity.
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| #* Other drugs that cause PVCs are quinidine, PCA, norpace, phenothiazines and tricyclic antidepressants.
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| # Electrolyte Imbalance:
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| #* [[Hypokalemia]], [[hypomagnesemia]], and [[hypercalcemia]] are frequently associated with the appearance of ventricular arrhythmias.<ref>Chou's Electrocardiography in Clinical Practice Third Edition, pp. 398-409.</ref> <ref>Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:194 ISBN 1591032016</ref>
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| ==Possible triggers== | | ==[[Premature ventricular contraction risk factors|Risk Factors]]== |
| *[[Anxiety]]/[[Stress (medicine)|Stress]]
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| *Chocolate
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| *[[Caffeine]]
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| *[[Electrolyte disturbance|Calcium/magnesium imbalance]]
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| *[[Dehydration]]
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| *[[Alcohol]]
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| *Exercise
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| *[[Hormones|Hormonal imbalance]]
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| *[[Hypercapnia]] ([[CO2 poisoning|CO<sub>2</sub> poisoning]])
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| *Hyperstimulation of the [[Vagus nerve]]
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| *[[Sleep deprivation|Lack of sleep]]/exhaustion
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| *[[Overeating]]
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| *Low [[copper]]
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| *[[Monosodium glutamate]] ([[MSG]])
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| == Epidemiology and Demographics == | | ==[[Premature ventricular contraction natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
| PVCs are a very common form of arrhythmia, and can occur in both individuals with and without [[heart disease]]. They can also occur in otherwise healthy athletes (e.g. in the days following a major effort such as a marathon. Estimates of the prevalence of PVCs vary greatly.
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| In children, PVCs occur less frequently than in adults, although healthy children are known to have episodes of PVC. In fact, on routine monitoring of children aged 10-13 years with a [[Holter monitor]], about 20% of healthy boys had occurrences of PVC. In otherwise healthy newborns, PVCs will often resolve on their own by the 12th week of life, and almost never require treatment.
| | ==Diagnosis== |
| | | [[Premature ventricular contraction history and symptoms|History and Symptoms]] | [[Premature ventricular contraction_physical_examination|Physical Examination]] | [[Premature ventricular contraction laboratory findings|Laboratory Findings]] | [[Premature ventricular contraction electrocardiogram|Electrocardiogram]] | [[Premature ventricular contraction EKG examples|EKG Examples]] | [[Premature ventricular contraction chest x-ray|Chest X Ray]] | [[Premature ventricular contraction echocardiography|Echocardiography]] | [[Premature ventricular contraction cardiac MRI|Cardiac MRI]] | [[Premature ventricular contraction coronary angiography|Coronary Angiography]] |
| == Natural History, Complications, Prognosis== | |
| *In the absence of [[ischemic heart disease]] ([[CAD]]) or [[hypertension]] ([[HTN]]), there is no excess risk of mortality in patients with PVCs.
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| * On the other hand, PVCs in the presence of structural cardiac abnormalities or [[hypertension]] is associated with a mortality twice that expected.
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| * The development of sustained [[ventricular tachycardia]] ([[VT]]) is most likely among those patients with greater than 12 PVCs/min, [[couplets]], and multifocal PVCs.
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| * Complex [[ventricular ectopic activity]] ([[VEA]]) during acute phase of STEMI does not have any prognostic significance.
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| * Their presence 2 to 3 weeks after acute MI is associated with a 3 fold increase in the risk of sudden death.
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| == Diagnosis ==
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| PVCs are diagnosed by an [[ECG]] or a TMT but some patients will need to wear a [[Holter monitor]] to record PVCs that occur outside the [[medical doctor|doctor's]] office or [[hospital]]. PVCs are often [[benign]] but may be a sign of a [[heart condition]]. PVCs may be unifocal (coming from the same part of the heart and having the same shape on the ECG) or multifocal (coming from several parts of the heart and having various shapes on the ECG). On the ECG, PVCs are diagnosed by: '''1'''. prematurity '''2'''. wide QRS '''3'''. the presence (usually) of a compensatory pause.
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| In healthy individuals, PVCs can often be resolved with continuous [[rehydration]] and by repleting the balance of [[magnesium]], [[calcium]] and [[potassium]] within the body.
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| === Electrocardiogram ===
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| # The beats are premature in relation to the expected beat of the basic rhythm
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| # Ectopic beats from the same focus tend to have a constant coupling interval (the interval between the ectopic beat and the preceding beat of the basic [[sinus rhythm]]).
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| #* They do not vary from each other by more than 0.08 seconds if the focus is the same.
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| #* PVCs with the same morphology but with a varying coupling interval should make one suspect a parasystolic mechanism.
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| #* A longer RR interval is followed by a relatively longer coupling interval
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| # The [[QRS]] complex is abnormal in duration and configuration. There are secondary [[ST segment]] and [[T wave]] changes. The morphology of the [[QRS]] may vary in the same patient.
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| #* If the [[PVC]] originates from the [[RV]] then the [[QRS]] has a [[LBBB]] morphology
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| #* The duration of the [[QRS]] is >0.12 seconds, but a narrower [[QRS]] may occur if the focus is higher in the septum.
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| #* The T wave is inverted and the [[ST segment]] is depressed.
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| # There is usually a full compensatory pause following the [[PVC]].
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| #* The sum of the RR intervals that precede and follow the ectopic beat (or the RR interval that contains the [[PVC]]) equals two RR intervals of the sinus beats.
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| #* Because of sinus arrhythmia, the RR interval that contains the [[PVC]] may not be exactly twice the duration of the RR interval of the adjacent sinus beat, even though a full compensatory pause does exist).
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| # Retrograde capture may or may not occur.
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| # They may occur in various frequency and distribution patterns such as [[bigeminy]], trigeminy (occurrence of a PVC every third beat), quadrigeminy (occurrence of a PVC every fourth beat), and couplets (Two ventricular premature complexes in a row). These are called complex [[PVC]]s.
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| #* The Rule of [[Bigeminy]]:
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| #*:# [[PVC]]s frequently occur after a long RR interval.
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| #*:# The compensatory pause of the precipitated [[PVC]] constitutes another long RR interval, which in turn favors the appearance of another [[PVC]].
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| #*:# Therefore bigeminy tends to perpetuate itself.
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| # Occasionally [[PVC]]s may be interpolated.
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| #* Between 2 beats without disturbing NSR.
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| #* Occurs mostly when the NSR is slow and the [[PVC]] is early.
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| #* The PR following the [[PVC]] is nearly always prolonged because of concealed retrograde conduction of the ectopic ventricular impulse, which renders the AV junction partially refractory.<ref>Chou's Electrocardiography in Clinical Practice Third Edition, pp. 398-409.</ref> <ref>Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:194 ISBN 1591032016</ref>
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| {| align="center"
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| |-valign="top"
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| | [[Image:PVCVF003.jpg|thumb|Premature Ventricular Contractions]] | |
| | [[Image:PVCVF002.jpg|thumb|Premature Ventricular Contractions triggering VF]] | |
| |} | |
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| ====Grading of Frequency====
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| # Called frequent if there are 5 or more [[PVC]]s per minute on the routine [[ECG]]
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| # '''Lown''' and '''Graboys''' proposed the following grading system which is used for prognostic purposes:
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| #* Grade 0 = No PVCs
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| #* Grade 1 = Occasional (<30 per hour)
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| #* Grade 2 = Frequent (>30 per hour)
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| #* Grade 3 = Multiform
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| #* Grade 4 = Repetitive
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| #*:# A = Couplets
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| #*:# B = Salvos of > 3
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| #* Grade 5 = R-on-T
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| ==Treatment== | | ==Treatment== |
| If the patient is asymptomatic, no treatment may be necessary. The following may reduce the frequency of PVCs:
| | [[Premature ventricular contraction medical therapy|Medical Therapy]] | [[Premature ventricular contraction electrical cardioversion|Electrical Cardioversion]] | [[Premature ventricular contraction ablation|Ablation]] | [[Premature ventricular contraction surgery|Surgery]] | [[Premature ventricular contraction primary prevention|Primary Prevention]] | [[Premature ventricular contraction secondary prevention|Secondary Prevention]] | [[Premature ventricular contraction cost effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Premature ventricular contraction future or investigational therapies|Future or Investigational Therapies]] |
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| * Avoiding PVC causes and triggers
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| *[[Magnesium]] supplements (e.g. [[magnesium citrate]])
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| *[[Calcium]] supplements (e.g. citrate)
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| *[[Potassium citrate]]
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| *[[Beta blocker]]s ([[Propranolol]], [[Atenolol]], [[Metoprolol|Toprol XL]])
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| Therapies with limited data to support their use:
| | ==Case Studies== |
| *[[Fish oil]]
| | [[Premature ventricular contraction case study one|Case #1]] |
| *[[Alprazolam|Xanax]]
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| ==See also== | | ==Related Chapters== |
| | *[[Ventricular tachycardia]] |
| *[[Bigeminy]] | | *[[Bigeminy]] |
| *[[Premature atrial contraction]] | | *[[Premature atrial contraction]] |
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| ==References==
| | [[Category:Disease]] |
| {{reflist|2}}
| | [[Category:Electrophysiology]] |
| | [[Category:Cardiology]] |
| | [[Category:Arrhythmia]] |
| | [[Category:Emergency medicine]] |
| | [[Category:Intensive care medicine]] |
| | [[Category:Best pages]] |
| | [[Category:Up-To-Date cardiology]] |
| | [[Category:Up-To-Date]]] |
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| ==External Links==
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| * [http://en.ecgpedia.org ECGpedia: Course for interpretation of ECG]
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