User:Mfigueroa12/sandbox

Questions & Notes Based on Article: AV Block

• Is each fact referenced with an appropriate, reliable reference?

This article only has one reference, and two external links listed. Although this article is fairly short, there are not direct citations after every fact given on whether the fact was found from the reference link or the external links. I think the facts need to be referenced more clearly and more often. If they are all from that one reference, then that is different but it should be specified. The video and pictures should be referenced more clearly.

• Is everything in the article relevant to the article topic? Is there anything that distracted you?

Everything mentioned in the article is relevant to the topic, and there is nothing that was distracting but I feel as if nothing was explained thoroughly. A more detailed explanation of what exactly an AV block is could be useful. Especially when the causes are discussed, it is very brief and not enough information is given regarding the causes. One could also add more information about the different types of AV Blocks: first-degree, second-degree, and third-degree. Only a brief bullet point explains which each degree is and if one does not understand the topic fully, they I worry they would not understand the bullet point information all together. A more detailed explanation should be added as well.

• Is the article neutral? Are there any claim, or frames, that appear heavily biased toward a particular side?

Yes, the article is very neutral and there appears to be no biased statements.

• Where does the information come from? Are these neutral sources? If biased, is that bias noted?

The information comes from one reference:

Lily, Leonard (2006). Pathophysiology of Heart Disease. Lippincott Williams and Wilkins.

The article also lists two external links which both come from medical websites such as eMedicine & Univ. of Maryland Medical Center Website.

• Are there viewpoints that are overrepresented, or underrepresented?

As mentioned earlier, nothing is really overrepresented or discussed in too grave of detail. This article needs more substance and more of a thorough explanation of the topics covered such as causes and types of AV block.

• Check a few citations. Do the links work? Is there any close paraphrasing or plagiarism in the article?

All of links and reference that are listed work and appear to be very credible references.There appears to be no plagiarism, in fact the links that are referenced help explain the subject matter a lot more in detail, so these could be good resources for editing/adding to this article.

I would like to note that there is a video explanation of an AV Block, but I do not see it referenced to a source. It is a very good visual and explanation but should be more clearly cited.

• Is any information out of date? Is anything missing that could be added?

As mentioned earlier, this article is very short and after looking through the reference links and articles listed along with other sources there is a very good amount of information that could be added, but nothing appears to be out of date. This article briefly discusses what an AV block is, a few causes and an overview of the three different types of blocks but that is all.

• How does the Wiki article compare to the ways we've discussed this topic in class? Does it align? What information ight be incorrect or missing?

URL for article discussing: https://en.wikipedia.org/wiki/Atrioventricular_block

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Adding to an article:

"First-Degree Atrioventricular (AV) Block, or first-degree heart block, is defined as prolongation of the PR interval on an electrocardiogram (ECG) to more than 200 msec. The PR interval of the surface ECG is measured from th onset of attain depolarization (P wave) to the beginning of ventricular depolarization (QRS complex). Normally, this interval should be between 120 and 200 msec in the adult population. First-degree AV block is considered "marked" when the PR interval exceeds 300 sec." - http://emedicine.medscape.com/article/161829-overview

"Signs and symptoms of atrioventricular (AV) block include the following:

• First-degree AV block: Generally not associated with any symptoms; it is usually an incidental finding on electrocardiography
• Second-degree AV block: Usually is asymptomatic, but in some patients, sensed irregularities of the heartbeat, presyncope, or syncope may occur; may manifest on physical examination as bradycardia (especially Mobitz II) and/or irregularity of heart rate (especially Mobitz I [Wenckebach])
• Third-degree AV block: Frequently associated with symptoms such as fatigue, dizziness, light-headedness, presyncope, and syncope; associated with profound bradycardia unless the site of the block is located in the proximal portion of the atrioventricular node (AVN)" - http://emedicine.medscape.com/article/151597-overview

Rewrite:

In order to differentiate between the different degrees of the atrioventricular block (AV block), the First-Degree AV block occurs when an electrocardiogram (ECG) reads a PR interval that is more than 200 msec. This degree, is typically asymptomatic and is only found through an ECG reading. Second-Degree AV block although typically asymptomatic, there are early signs that can be dictated or are noticeable such as irregular heartbeat or a syncope. A Third-Degree AV block has noticeable symptoms that present itself as more urgent such as: dizziness, fatigue, chest pain, pre syncope, or syncope.

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Week 4

- We plan to contribute by adding more information regarding the different degrees of the block, adding more specific definitions and a better understanding of the block in its entirety.

- We also plan to discuss the different effects and causes of the AV block as well as steps necessary after a block occurs such as necessary treatments.

- How one could identify a heart block and how to treat one.

Bibliography/Websites:

http://www.merckmanuals.com/professional/cardiovascular-disorders/arrhythmias-and-conduction-disorders/atrioventricular-block

http://emedicine.medscape.com/article/151597-overview

http://www.uptodate.com/contents/etiology-of-atrioventricular-block

http://ecg.utah.edu/lesson/6

http://my.clevelandclinic.org/health/articles/heart-block

http://emedicine.medscape.com/article/162007-overview

http://ajcc.aacnjournals.org/content/12/1/77.full

http://www.jems.com/articles/print/volume-39/issue-1/features/how-recognize-treat-heart-block.html

Adding to article:

Though the author describes three different types of atrioventricular blocks, it is challenging to understand their descriptions. For example, the first type, a first-degree atrioventricular block, is described as a “PR interval greater than 0.20sec.” This should be further explained in order to interpret the attached image showing its respective cardiac rhythm. For further editing, there should be a description of the implementations of atrioventiruclar blocks, such as its effects on the human body. There should be descriptions of how these blockages are treated and how they could be prevented. I also think the article should include the prevalence of these blockages in the population, particularly common ages of onset or if the blockage exist at birth. - Victoria Gallina (Partner)

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Week 5

Improvement Notes:

Nothing is really overrepresented or discussed in too grave of detail, this article needs to explain the different degrees of the AV blocks including definitions, treatment plans, and examples. This article needs more substance and more of a thorough explanation of the topics covered such as causes and types of AV block, treatments of the various blocks, how one could detect a block, etc. We are looking to improve these topic areas but would also like to add more references as well because this page only showed one reference before we added to it in a previous week.

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Week 6

Drafting improvements:

- In order to differentiate between the different degrees of the atrioventricular block (AV block), the First-Degree AV block occurs when an electrocardiogram (ECG) reads a PR interval that is more than 200 msec. This degree, is typically asymptomatic and is only found through an ECG reading. Second-Degree AV block although typically asymptomatic, there are early signs that can be dictated or are noticeable such as irregular heartbeat or a syncope. A Third-Degree AV block has noticeable symptoms that present itself as more urgent such as: dizziness, fatigue, chest pain, pre syncope, or syncope.

- Laboratory Diagnosis for AV blocks include electrolyte and drug level and cardiac enzyme level tests. A clinical evaluation also looks at infection, myxedema, or connective tissue disease studies.(http://emedicine.medscape.com/article/151597-overview)

- In order to properly diagnose a patient with AV block, a route electrocardiographic recording must be completed (ECG). Based on the P waves and QRS complexes that can be evaluated from these readings, that relationship will be the standardized test if an AV block is present or not. In order to identify this block based on the readings the following must occur: "24-hour Holter monitoring, even (loop) ECG readings, multiple ECG readings, and monitoring with implantable loop recorders" (http://emedicine.medscape.com/article/151597-overview)

- Management of an AV block includes a pacemaker implantation and pharmacologic therapy. Pacemaker implantation depends on the type of AV block present in a patient.

• "First-degree AV block and Mobitz I second-degree AV block: Do not generally require treatment unless they cause symptoms and are not due to a reversible cause 
• Mobitz II second-degree AV block and third-degree AV block: Usually require temporary and/or permanent cardiac pacing
• Third-degree AV block: Patients with persistent bundle branch block and transient third-degree AV block may benefit from permanent pacing therapy, especially after anterior myocardial infarction; nonrandomized studies strongly suggest that permanent pacing improves survival in patients with third-degree AV block, especially if syncope has occurred" - REWORD OR CITE (http://emedicine.medscape.com/article/151597-overview)

Pharmacologic therapy includes administering anticholinergic agents and is dependent on severity of blockage. In severe cases or emergencies, atropine administration or isoproterenol infusion would allow for temporary relief if bradycardia is the cause for the blockage, but if His-Purkinje system is the result of the AV block then pharmacologic therapy is not recommended.

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Week 7

First-Degree Atrioventricular block: The heart’s electrical signals move between the upper and lower chambers of the heart. Out of the three types of atrioventricular block, this is the least severe for it could be asymptomatic and not need any specific treatment. 

Second-Degree Atrioventricular block: The heart’s electrical signals between the upper and lower signals of the heart are slowed by a much greater rate than in first-degree atrioventricular block.

There are two subtypes of atrioventricular block:

 Mobitz Type 1 and Mobitz Type II

Third Degree Atrioventricular block: The heart’s electrical signals are slowed to a complete halt. This means that none of the the signals reach either the upper or lower chambers causing a complete blockage of the ventricles and can result in cardiac arrest. Third-degree atrioventricular block is the most severe of the types of heart ventricle blockages. Persons suffering from symptoms of third-degree heart block need emergency treatment including but not limited to a pacemaker.

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Week 9/Week 10

Additions made to actual article:

Laboratory diagnosis for AV blocks include electrolyte, drug level and cardiac enzyme level tests. A clinical evaluation also looks at infection, myxedema, or connective tissue disease studies. In order to properly diagnose a patient with AV block, a electrocardiographic recording must be completed (ECG). Based on the P waves and QRS complexes that can be evaluated from these readings, that relationship will be the standardized test if an AV block is present or not. In order to identify this block based on the readings the following must occur: multiple ECG recordings, 24-hour Holter monitoring, and implant loop recordings. Other examinations for the detection of an AV block include electrophysiologic testing, echocardiography, and exercise.

Mobitz I is characterized by a reversible block of the AV node. When the AV node is severely blocked, it fails to conduct an impulse. Mobitz I is a progressive failure. Some patients are asymptomatic; those who have symptoms respond to treatment effectively. There is low risk of the AV block leading to heart attack. 

Mobitz II is characterized by a failure of the His-Purkinje cells resulting in the lack of a supra ventricular impulse. These cardiac His-Purkinje cells are responsible for the rapid propagation in the heart. Mobitz II is caused by a sudden and unexpected failure of the His-Purkinje cells. The risks and possible effects of Mobitz II are much more severe than Mobitz I in that it can lead to severe heart attack. https://www.ncbi.nlm.nih.gov/pubmed/8445186

Everything added to actual article thus far is in bold:

Atrioventricular block (AV block) is a type of heart block in which the conduction between the atria and ventricles of the heart is impaired. Under normal conditions, the sinoatrial node (SA node) in the atria sets the pace for the heart, and these impulses travel down to the ventricles. In an AV block, this message does not reach the ventricles or is impaired along the way. The ventricles of the heart have their own pacing mechanisms, which can maintain a lowered heart rate in the absence of SA stimulation.

The causes of pathological AV block are varied and include ischaemia, infarction, fibrosis or drugs, and the blocks may be complete or may only impair the signaling between the SA and AV nodes. Certain AV blocks can also be found as normal variants, such as in athletes or children, and are benign. Strong vagal stimulation may also produce AV block. The cholinergic receptor types affected are the muscarinic receptors.

There are three types:

• First-degree atrioventricular block - The heart’s electrical signals move between the upper and lower chambers of the heart. PR intervalgreater than 0.20sec.
• Second-degree atrioventricular block - The heart’s electrical signals between the upper and lower signals of the heart are slowed by a much greater rate than in first-degree atrioventricular block. Type 1 (a.k.a. Mobitz 1, Wenckebach): Progressive prolongation of PR interval with dropped beats (the PR interval gets longer and longer; finally one beat drops) . Type 2 (a.k.a. Mobitz 2, Hay): PR interval remains unchanged prior to the P wave which suddenly fails to conduct to the ventricles.
  • Mobitz I is characterized by a reversible block of the AV node. When the AV node is severely blocked, it fails to conduct an impulse. Mobitz I is a progressive failure. Some patients are asymptomatic; those who have symptoms respond to treatment effectively. There is low risk of the AV block leading to heart attack.  Mobitz II is characterized by a failure of the His-Purkinje cells resulting in the lack of a supra ventricular impulse. These cardiac His-Purkinje cells are responsible for the rapid propagation in the heart. Mobitz II is caused by a sudden and unexpected failure of the His-Purkinje cells. The risks and possible effects of Mobitz II are much more severe than Mobitz I in that it can lead to severe heart attack.
• Third-degree atrioventricular block - No association between P waves and QRS complexes. The heart’s electrical signals are slowed to a complete halt. This means that none of the the signals reach either the upper or lower chambers causing a complete blockage of the ventricles and can result in cardiac arrest. Third-degree atrioventricular block is the most severe of the types of heart ventricle blockages. Persons suffering from symptoms of third-degree heart block need emergency treatment including but not limited to a pacemaker.

In order to differentiate between the different degrees of the atrioventricular block (AV block), the First-Degree AV block occurs when an electrocardiogram (ECG) reads a PR interval that is more than 200 msec. This degree is typically asymptomatic and is only found through an ECG reading. Second-Degree AV block, although typically asymptomatic, has early signs that can be detected or are noticeable such as irregular heartbeat or a syncope. A Third-Degree AV block has noticeable symptoms that present themselves as more urgent such as: dizziness, fatigue, chest pain, pre syncope, or syncope.

Laboratory diagnosis for AV blocks include electrolyte, drug level and cardiac enzyme level tests. A clinical evaluation also looks at infection, myxedema, or connective tissue disease studies. In order to properly diagnose a patient with AV block, a electrocardiographic recording must be completed (ECG). Based on the P waves and QRS complexes that can be evaluated from these readings, that relationship will be the standardized test if an AV block is present or not. In order to identify this block based on the readings the following must occur: multiple ECG recordings, 24-hour Holter monitoring, and implant loop recordings. Other examinations for the detection of an AV block include electrophysiologic testing, echocardiography, and exercise.

Management includes a form of pharmacologic therapy that administers anticholinergic agents and is dependent upon the severity of a blockage. In severe cases or emergencies, atropine administration or isoproterenol infusion would allow for temporary relief if bradycardia is the cause for the blockage, but if His-Purkinje system is the result of the AV block then pharmacologic therapy is not recommended.