Study with Quizlet and memorize flashcards containing terms like WAP is one of three ___ ___ rhythms., The three irregularly irregular rhythms include (pick all that apply): A. WAP B. PAC C. MAT D. AF E. Accelerated junctional, Respiratory variations and metabolic changes that occur during respiration can cause a temporary fluctuation of the main area that actually stimulates the impulse ... Third Degree Heart Block. Third Degree Heart Block. Atrial Pacing. Single Chamber Ventricular Pacing. AV Sequential Pacing. Failure to sense. Failure to capture. Failure to pace/ output. Study with Quizlet and memorize flashcards containing terms like Normal Sinus, Normal Sinus, Normal Sinus and more.It's a sight for sore eyes. It’s a sight for sore eyes. Wycombe Wanders, a club in the fourth division of professional soccer in the UK, unveiled its new jerseys for next season Ju...Study with Quizlet and memorize flashcards containing terms like What is a Wandering Atrial Pacemaker?, What is the Heart Rate in a WAP?, What is the Rhythm in a WAP? …Study with Quizlet and memorize flashcards containing terms like rhythm, rate, P wave morphology and more.Unicorns are beautiful but fragile. Camels are survivors. The education technology industry is having a moment. When Covid-19 lockdowns sent 1.7 billion learners home, leaving teac...Wandering atrial pacemaker and multifocal atrial tachycardia have three different shape... Supraventricular. Arising from a pacemaker above the ventricle.Study with Quizlet and memorize flashcards containing terms like Conduction to the atria in junctional rhythms is said to be:, Blood clots collecting in the atria are a possible complication of what rhythm?, The rhythm called wandering atrial pacemaker has at least three different shapes of: and more.An atrial myxoma is a noncancerous tumor in the upper left or right side of the heart. It most often grows on the wall that separates the two sides of the heart. This wall is calle...Study with Quizlet and memorize flashcards containing terms like Which wave is most affected by a change in electrical activity within the atria ?, Premature atrial complexes, Atrial Flutter and more. ... Which dysrhythmia is similar to wandering atrial pacemaker, except that the rate exceeds 100bpm. Multi focal atrial tachycardia.Study with Quizlet and memorize flashcards containing terms like Rhythm is slightly irregular Rate 60-100 bpm P Wave has continuous changes (3 diff waves) PR interval varies QRS duration normal, WAP can be related to organic heart disease or drug toxicity WAP is a normal finding in children, older adults, and well-conditioned athletes., A more serious atrial Dysrhythmia and more. a ventricular rate faster than 180 beats/min. True. Identify the following rhythm (lead Il). Wolff-Parkinson-White syndrome. Multifocal atrial tachycardia is another name for atrial fibrillation. False. P waves in this rhythm strip___. Are not identifiable. The most common type of supraventricular tachycardia (SVT) is. occurs when the pacemaking impulses originate from at least three different foci in the atria. One of these atrial foci may be the sinus node or the AV node, as you'll recall both are located in the atria. Each different focus produces its own unique P wave, resulting in a rhythm with at least three different shapes of P waves. WAP is an example of a slow …Start studying Wandering Atrial Pacemaker. Learn vocabulary, terms, and more with flashcards, games, and other study tools.Study with Quizlet and memorize flashcards containing terms like What is meant by "controlled" a-fib?, 3 or more PVCs?, Management of slow rhythms may require therapeutic intervention including? and more. ... A wandering atrial pacemaker rhythm with a ventricular rate of 60 to 100 BPM may also be referred to as? Multiformed atrial rhythm. … 2nd degree type 1, wenckebach 1, mobtiz 1. Going, going, gone. CPR or shock. what needs to be done if the patient is in asystole? Study with Quizlet and memorize flashcards containing terms like , Wandering Atrial Pacemaker, Premature Atrial Complex and more. Study with Quizlet and memorize flashcards containing terms like Which of the following rhythms is characterized by a narrow QRS, presence of multiple P wave shapes, irregularly irregular rhythm, variable PR interval, and a ventricular rate of 84 beats per minute? A. Atrial fibrillation B. Wandering atrial pacemaker C. Multifocal atrial tachycardia D. Complete heart block, The rhythm most ...When a wandering atrial pacemaker rhythm speeds up with a ventricular rate greater than 100, it is then called: paroxysmal SVT. You observe a patient in a normal sinus rhythm. The patient's heart rate increases to 180 maintaining a narrow complex. Within a few seconds, the rate returns to 70. This patient experienced.Study with Quizlet and memorize flashcards containing terms like A 77-year-old woman is complaining of a sudden onset of palpitations. The cardiac monitor reveals atrial fibrillation with a ventricular response of 144 to 210 beats/min while the patient is at rest. In this situation, the ventricular rate associated with this rhythm is considered to be _____., …Multifocal Atrial Tachycardia. What dysrhythmia is similar to Wandering atrial pacemaker,but the rate exceeds 100 bpm. Thrombus formation and embolization.Study with Quizlet and memorize flashcards containing terms like A first-degree heart block has a PR interval greater than 0.20 seconds because: A) impulses generated by the SA mode traverse the AV node at an accelerated rate B) the primary pacemaker is not the SA node, but rather an ectopic atrial pacemaker C) depolarization of the atria occurs at a …Wandering Atrial Pacemaker occurs when the pacemaking impulses originate from at least three different foci in the atria. One of these atrial foci may be the sinus node or the AV node, as you'll recall both are located in the atria.EKG Chapter 6 Atrial Dysrhythmias. Get a hint. atrial dysrhythmias. Click the card to flip 👆. caused by ectopic impulse in right or left atrium. occur from conditions that cause pressure on the atria. Click the card to flip 👆. 1 / 54.Quizlet has study tools to help you learn anything. Improve your grades and reach your goals with flashcards, practice tests and expert-written solutions today. Match. Wandering Atrial Pacemaker. Log in. Sign up. Ready to play? Match all the terms with their definitions as fast as you can.EKG Chapter 6 Atrial Dysrhythmias. Get a hint. atrial dysrhythmias. Click the card to flip 👆. caused by ectopic impulse in right or left atrium. occur from conditions that cause pressure on the atria. Click the card to flip 👆. 1 / 54.atrium that fires repetitively at a very rapid rate. rules for atrial tachycardia. regularity: regular. rate: 150-250 bpm. P wave: atrial P wave; differs from sinus P wave; can be lost in T wave (P waves will all look the same) PRI: 0.12-0.20 second. QRS: < 0.12 second. atrial flutter occurs when.A) Wandering atrial pacemaker. B) Atrial flutter. C) Atrial fibrillation. D) Multifocal atrial tachycardia. D. You are asked to perform an ECG on a 7-year-old child. The child is active and appears to be in good health. When you check the ECG tracing, you notice that it shows a wandering atrial pacemaker rhythm.Study with Quizlet and memorize flashcards containing terms like What common complication of atrial fibrillation be prevented by the use of anticoagulant medications?, The rhythm that is the same as wandering atrial pacemaker except for the heart rate is _____, The rhythm that is the produces V-shaped waves between QRS complexes is _____ and …Study with Quizlet and memorize flashcards containing terms like The rhythm in which ALL atrial activity is depicted as chaotic undulations of the baseline is called: -atrial fibrillation -sinus tachycardia -atrial tachycardia -atrial flutter, The ventricular rate for PACs is defined as: -less than 10 bpm -greater than 100 bpm -depends on underlying rhythm -60-100 bpm, The QRS in Atrial ...Wandering Atrial Pacemaker (WAP) is a cardiac rhythm disorder that causes irregular and variable heartbeats. Learn the Heart - Healio provides a comprehensive ECG review of this condition ...Atrial fibrillation can be frightening or intimidating to some people who may be experiencing the symptoms for the very first time. Atrial fibrillation is an irregular, rapid heart... Wandering atrial pacemaker (WAP) is a benign cardiac arrhythmia that occurs when impulses are not generated only in the SA node, but in at least two more sources nearby the SA node. This means an ECG of a patient with WAP will show at least three different shapes of P waves . Wandering atrial pacemaker and multifocal atrial tachycardia have three different shape... Supraventricular. Arising from a pacemaker above the ventricle.Study with Quizlet and memorize flashcards containing terms like What is the rate of the wandering atrial pacemaker rhythm?, Atrial kick, What dysrhythmia is similar to WAP, but the rate exceeds 100 bpm? and more.A wandering atrial pacemaker rhythm with a ventricular rate of 60 to 100/min may also be referred to as _____. atrial fibrillation. atrial flutter. multiformed atrial rhythm. sinus rhythm. 12 of 21. Term. ... Quizlet for Schools; Language Country. United States; Canada ...Wandering Atrial Pacemaker Rhythm Strip Features. Rate: Normal (60-100 bpm) Rhythm: May be irregular. P Wave: Changing shape and size from beat to beat (at least three different forms) PR Interval: Variable. QRS: Normal (0.06-0.10 sec) The electrical impulses causing the atrial activity are moving or wandering.Wandering atrial pacemaker is a: normal finding in children, older adults, and well-conditioned athletes and does not usually cause clinical signs and symptoms. What dysrhythmia is similar to wandering atrial pacemaker, but the rate exceeds 100 beats per minute?Study with Quizlet and memorize flashcards containing terms like Identify the following rhythm:, ... What is the rate of wandering atrial pacemaker rhythm ( WAP ) ? 60 to 100 beats per minute. Which atrial dysrhythmia has capital F waves and a classic sawtooth or picket fence appearance ?Study with Quizlet and memorize flashcards containing terms like Myocardial infarction, valvular problems, neurological influences, the waveform has an equally positive and negative deflection on the ECG tracing, Premature Atrial Complexes (PAC) and more. ... What is the rate of wandering atrial pacemaker rhythm (WAP)? 101-150 beats per …In a patient with wandering pacemaker the ECG strip will show. slight irregularity because sites of impulse initiation vary. The best way to study. Sign up ...An decrease in temperature from 37.3° to 36.9° C (99.1° to 98.4° F) B. An increase in pulse rate from 76 to 84/min. C. An increase in blood pressure from 120/80 to 128/84 mm Hg. D. An increase in respirations from 18 to 36/min. An increase in respirations from 18 to 36/min. Study with Quizlet and memorize flashcards containing terms like ...Study with Quizlet and memorize flashcards containing terms like Multifocal atrial tachycardia is an irregular rhythm with a heart rate greater than 100., Blood clots in the atria are associated with multifocal atrial tachycardia., An ectopic rhythm is one which originates in a location other than the sinus node. and more.Study with Quizlet and memorize flashcards containing terms like A delta wave is identified on a cardiac rhythm strip as a(n): A - slurring of the upstroke of the first part of the QRS complex. B - apparent P wave that occurs at the end of the QRS complex. C - delay between the end of the P wave and the beginning of the R wave. D - acute widening of …The rhythm most often associated w/ chronic lung disease is. Multifocal atrial tachycardia. A PAC is a. Premature beat from the atrium. Atrial tachycardia is characterized by. Abnormal P waves preceding the regular QRS complexes. Atrial flutter has an atrial rate. Between 250 and 350. Wandering atrial pacemaker has at least 3 different shapes of.Study with Quizlet and memorize flashcards containing terms like atrial dysrhythmias occur from conditions that cause pressure on the atria such as, atrial flutter occurs?, what dysrhythmia is simliar to wandering atrial pacemaker, but the rate exceeds 100 BPM and more. Study with Quizlet and memorize flashcards containing terms like Which of the following rhythms is characterized by a narrow QRS, presence of multiple P wave shapes, irregularly irregular rhythm, variable PR interval, and a ventricular rate of 84 beats per minute? A. Atrial fibrillation B. Wandering atrial pacemaker C. Multifocal atrial tachycardia D. Complete heart block, The rhythm most ... Treatment. If the patient is asymptomatic, observation is all that is required. If the patient is symptomatic, consider adenosine. Study with Quizlet and memorize flashcards …QRS: 0.10 second. Interpretation: Atrial fibrillation. 19 of 19. Quiz yourself with questions and answers for Chapter 6 Quiz, so you can be ready for test day. Explore quizzes and practice tests created by teachers and students or create one from your course material.Match. Study with Quizlet and memorize flashcards containing terms like What is it?, What is the heart rate with wandering atrial pacemaker?, What are the EKG findings associated with wandering atrial pacemaker? and more.Wandering Atrial Pacemaker Rhythm: Regular or irregular Rate:Usually normal (60 to 100 beats/minute) but may be slow (less than 60 beats/minute) P waves:Vary in size, shape, and direction across rhythm strip; one P wave precedes each QRS complex PR interval:Usually normal duration, but may be abnormal depending on changing pacemaker location ..."Wandering atrial pacemaker" and "multifocal atrial tachycardia" are two irregular heart rhythms that differ in their underlying mechanisms and clinical significance. Wandering atrial pacemaker describes a condition in which the pacemaker activity shifts between various regions of the atria, typically without causing significant symptoms or …Quizlet has study tools to help you learn anything. Improve your grades and reach your goals with flashcards, practice tests and expert-written solutions today. The rhythm most often associated w/ chronic lung disease is. Multifocal atrial tachycardia. A PAC is a. Premature beat from the atrium. Atrial tachycardia is characterized by. Abnormal P waves preceding the regular QRS complexes. Atrial flutter has an atrial rate. Between 250 and 350. Wandering atrial pacemaker has at least 3 different shapes of. Preview. Pharmacology 5-1: Heart Failure Treatment. 70 terms. kasidycarson. Preview. The characteristics of an atrial pacemaker and features that are shared by all rhythms originating in the atria.Study with Quizlet and memorize flashcards containing terms like Which 3 rhythms are shockable?, ... A wandering atrial pacemaker: A. has consistent P wave shapes. B. is generally faster than 100 beats/min. C. may have variable P-R intervals. D. is generally treated with atropine.A pacemaker is a small, battery-operated device. This device senses when your heart is beating too slowly. It sends a signal to your heart that makes your heart beat at the correct...Study with Quizlet and memorize flashcards containing terms like Which resources must be available for a patient undergoing an invasive stress test ?, What is the minimum number of variations of the P wave in a wandering atrial pacemaker rhythm?, An ECG technician should recognize that the most likely cause of a PVC on an ECG strip is ? and more.Study with Quizlet and memorize flashcards containing terms like What is the rate of the wandering atrial pacemaker rhythm?, Atrial kick, What dysrhythmia is similar to WAP, but the rate exceeds 100 bpm? and more.Study with Quizlet and memorize flashcards containing terms like What is the most common cause of atrial arrhyhmias?, What is atrial arrhythmia?, What is a wandering atrial pacemaker? and more.Study with Quizlet and memorize flashcards containing terms like Sinus Rhythm between the rates of 60-100 bpm ... Wandering Atrial Pacemaker: ... Describe it. Irregular rhythm produced by the pacemaker activity wandering from the SA Node to Nearby Atrial Automaticity foci. P prime wave shape varies Atrial rate less than 100 Irregular ... ECG Chapter 4. Get a hint. What is meant by "controlled" a-fib? Click the card to flip 👆. The overall ventricular rate is smaller than 100 BPM. Click the card to flip 👆. 1 / 40. Study with Quizlet and memorize flashcards containing terms like What is the term for a condition in which a patient's blood pressure is not adequate to maintain good blood supply to the vital organs?, Which atrial dysrhythmia has a clearly changing P wave and a heart rate of 101 to 150 beats per minute?, What is the ventricular heart rate with junctional … a ventricular rate faster than 180 beats/min. True. Identify the following rhythm (lead Il). Wolff-Parkinson-White syndrome. Multifocal atrial tachycardia is another name for atrial fibrillation. False. P waves in this rhythm strip___. Are not identifiable. The most common type of supraventricular tachycardia (SVT) is. Start studying Wandering Atrial Pacemaker. Learn vocabulary, terms, and more with flashcards, games, and other study tools.A variant of wandering atrial pacemaker. Occurs when the rate is 100 BPM or greater + 3 dif. P waves. A single electrical impulse that originates outside the SA node in the atria. The premature beat is a complex that arises earlier than next expected beat. Looks like normal complexes of underlying rhythm.Study with Quizlet and memorize flashcards containing terms like the natural firing rate of the SA node is, ... Wandering Atrial Pacemaker. slightly irregual , normal range can be slower 60-100 pwave changes 1 p wave in front of evr QRS complex less than .20 seconds qrs less than .12.Study with Quizlet and memorize flashcards containing terms like WAP is one of three _____ _____ rhythms., The three irregularly irregular rhythms include: A. WAP B. PAC C. MAT D. AF E. Accelerated junctional, Respiratory variations and metabolic changes that occur during respiration can cause a temporary fluctuation of the main area that actually stimulates the impulse within the SA node ...Pacemaker B. Automatic external defibrillator (AED) C. Telemedicine monitor D. 12-lead ECG and more. Study with Quizlet and memorize flashcards containing terms like -CHAPTER 1-2 EXAM- The minimum amount of pressure that is exerted against the walls of blood vessels at all times is the: A.diastolic blood ... D. atrial depolarization and ...Study with Quizlet and memorize flashcards containing terms like Multifocal atrial tachycardia, Atrial flutter, Atril fibrillation and more. ... Which dysrhythmia is similar to wandering atrial pacemaker, except that the rate exceeds 100 beats per …From Quizlet and Otter to BibMe and Speechify, one of these apps should help you get through your next class. Maybe you tend to study the old-school way: sit down, break out a high...From Quizlet and Otter to BibMe and Speechify, one of these apps should help you get through your next class. Maybe you tend to study the old-school way: sit down, break out a high...Study with Quizlet and memorize flashcards containing terms like Which of the following rhythms is characterized by a narrow QRS, presence of multiple P wave shapes, irregularly irregular rhythm, variable PR interval, and a ventricular rate of 84 beats per minute? A. Atrial fibrillation B. Wandering atrial pacemaker C. Multifocal atrial tachycardia D. Complete heart block, The rhythm most ...Mechanism for Wandering Atrial pacemaker the pacemaker site wanders between the sinus node, the atria, and the AV junction. Although each impulse originates from a different focus, the rate usually remains within a normal range but it can be slower or faster.Study with Quizlet and memorize flashcards containing terms like Atrial dysrhythmia mechanisms (3), Key characteristics of atrial dysrhythmias, Wandering atrial pacemaker Cause Is it normal in any population? Related to any diseases or medications? and more.Rate: 60 beats/minute. P waves: Vary in size and shape. PR interval: 0.08 to 0.12 second. QRS complex: 0.04 to 0.08 second. Interpretation: Wandering atrial pacemaker. …Study with Quizlet and memorize flashcards containing terms like What are atrial dysrhythmias caused by?, ... Wandering Atrial Pacemaker. About us. About Quizlet; How Quizlet works; Careers; Advertise with us; Get the app; For students. Flashcards; Test; Learn; Solutions; Q-Chat: AI Tutor;Preview. Pharmacology 5-1: Heart Failure Treatment. 70 terms. kasidycarson. Preview. The characteristics of an atrial pacemaker and features that are shared by all rhythms originating in the atria.Preview. Pharmacology 5-1: Heart Failure Treatment. 70 terms. kasidycarson. Preview. The characteristics of an atrial pacemaker and features that are shared by all rhythms originating in the atria.Study with Quizlet and memorize flashcards containing terms like Rhythm, Rate, P waves and more. ... Wandering Atrial Pacemaker (WAP) 5Step. Flashcards. Learn. Test ...Wandering atrial pacemaker/ectopic tachycardia is the passive transfer of pacemaker sites to other latent pacemaker sites in the atria and AV junction. Often, more than one pacemaker will be active causing variation in RR interval and P wave morphologyThe P wave of a PAC is shaped _____from sinus P waves. Diffrent. Wandering atrial pacemaker has at least _____ different shapes of P waves. 3. Multifocal atrial tachycardia is the same rhythm as _____, but with a faster heart rate. WAP. Paroxysmal atrial tachycardia is an atrial tachycardia that usurps the underlying. rhythm.Wandering atrial pacemaker/ectopic tachycardia is the passive transfer of pacemaker sites to other latent pacemaker sites in the atria and AV junction. Often, more than one pacemaker will be active causing variation in RR interval and P wave morphologyMULTIFOCAL ATRIAL TACHYCARDIA (MAT) OR CHAOTIC ATRIAL TACHYCARDIA. when wandering atrial pacemaker is associated with a VENTRICULAR RATE OVER 100 BPM. MAT ...A pacemaker is a small, battery-operated device. This device senses when your heart is beating too slowly. It sends a signal to your heart that makes your heart beat at the correct...a fast atrial rhythm caused by irritability in the atria, with a rate of 160-250 BPM. Multifocal Atrial Tachycardia (MAT) a rhythm related to wandering atrial pacemaker, but with a ventricular rate greater than 100 BPM. Supraventricular Tachycardia (SVT) can be a general term for all tachycardias (fast rhythms) that begin with impulses ...Choose matching definition. a tachycardic rhythm originating from a pacemaker site above the level of the ventricles. a regular tachycardic rhythm between 150 and 180 beats/min with P waves buried in the QRS complexes. any tachycardic rhythm with a heart rate greater than 130 beats/min and absent P waves.
ECG Chapter 4. Get a hint. What is meant by "controlled" a-fib? Click the card to flip 👆. The overall ventricular rate is smaller than 100 BPM. Click the card to flip 👆. 1 / 40. . Dorito dynamites
Digoxin is used to treat certain heart problems such as some arrhythmias (called atrial fibrillation and atrial flutter) and heart failure. An arrhythmia ... Try our Symptom Checke...Atrial fibrillation. -Continuous, rapid firing of multiple automaticity foci in atria. -No normal p waves visible. -Wavy baseline. -Irregular ventricular rhythm. -Most common sustained arrhythmia. Atrial flutter. -Atrial rate ~250-350 bpm. -Rapid succession of identical, back-to-back atrial depolarization waves from a single abnormal re-entry ...Which of the following statements is correct regarding multifocal atrial tachycardia (MAT)? A) It has the same characteristics as wandering atrial pacemaker (WAP) and a heart rate of 60 to 100 beats per minute. B) The MAT P waves remain the same from heart beat to heart beat. C) It can be distinguished from WAP by looking for visibly changing P ...Study with Quizlet and memorize flashcards containing terms like What is the rate of the wandering atrial pacemaker rhythm?, Atrial kick, What dysrhythmia is similar to WAP, but the rate exceeds 100 bpm? and more.Summary. Home Education Hypertrophic Cardiomyopathy for Professionals Hypertrophic Cardiomyopathy Pod...It's a sight for sore eyes. It’s a sight for sore eyes. Wycombe Wanders, a club in the fourth division of professional soccer in the UK, unveiled its new jerseys for next season Ju...Oct 20, 2023 ... ... atrial dysrhythmias is this patient most likely to develop? a. Wandering atrial pacemaker b. Atrial flutter c. Atrial fibrillation d ...a. it can spontaneously generate an electrical impulse. b. it has an intrinsic rate of 40-60 bpm. c. it is located at the atrioventricular (AV) junction. d. it allows time for the ventricles to fill. the sa node is referred to as the primary pacemaker of the heart. the sa node's firing rate is about 60-100 bpm. Study with Quizlet and memorize ...A variant of wandering atrial pacemaker Occurs when the rate is 100 BPM or greater + 3 dif. P waves What is Premature Atrial Complexes (PACs)? A single electrical impulse that originates outside the SA node in the atria The premature beat is a complex that arises earlier than next expected beat Looks like normal complexes of underlying rhythmStudy with Quizlet and memorize flashcards containing terms like What is the rate of the wandering atrial pacemaker rhythm?, Atrial kick, What dysrhythmia is similar to WAP, but the rate exceeds 100 bpm? and more.The Body's Electrical System - The natural pacemaker of the heart is called the sinoatrial node. Learn how your heart beats and the electrical impulses in your body. Advertisement ...Study with Quizlet and memorize flashcards containing terms like Wandering Atrial Pacemaker (WAP), Multifocal Atrial Tachycardia (MAT), Premature Atrial Complex (PAC) and more. ECG Chapter 4. Get a hint. What is meant by "controlled" a-fib? Click the card to flip 👆. The overall ventricular rate is smaller than 100 BPM. Click the card to flip 👆. 1 / 40. Study with Quizlet and memorize flashcards containing terms like What is the rate of the wandering atrial pacemaker rhythm?, Atrial kick, What dysrhythmia is similar to WAP, but the rate exceeds 100 bpm? and more.Study with Quizlet and memorize flashcards containing terms like Wandering Atrial Pacemaker, Multifocal Atrial Tachycardia (wont be on quiz strips), Premature Atrial Contractions and more..
Popular Topics
- Menards post driverHasa nyc housing
- Snooky pimpHarbor bridge jumper corpus christi today
- Accessmcd com loginHp specialty center
- Channel 7 morning news anchorsFort morgan ferry prices
- Cine apopkaHow to attach vinyl lattice
- Lakefront homes for sale on castle rock lake wiSeatguru boeing 777 200
- Little caesars romeEaston shooting columbus