Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Atrioventricular Block, Incomplete (Second-Degree)

atrioventricular block, incomplete (second-degree) in 中文(中华人民共和国)

Related Terms

  • 2:1 Atrioventricular Response Block
  • Atrioventricular Response Block
  • Mobitz Type I
  • Mobitz Type II
  • Second-degree AV Block
  • Second-degree Incomplete AV Block
  • Wenckebach Block

Differential Diagnosis

Specialists

  • Cardiologist, Cardiovascular Physician

Comorbid Conditions

  • Cardiovascular disease
  • Diabetes mellitus
  • Hypertension
  • Obesity

Factors Influencing Duration

Length of disability may be influenced by the underlying medical condition (e.g., AMI), method of treatment required, and individual's job requirements.

Medical Codes

ICD-9-CM:
426.12 - Atrioventricular Block, Mobitz (Type) II, Second Degree; Incomplete Atrioventricular Block
426.13 - Atrioventricular Block, Other Second Degree

Overview

Second-degree atrioventricular (AV) block refers to a delayed conduction of electrical impulses (which produce the heartbeats) from the upper chambers (atria) to the lower chambers of the heart (ventricles); some impulses are not conducted. Incomplete or second-degree block is divided into two types, Mobitz type I and Mobitz type II. Both are characterized by "dropped beats."

In Mobitz type I (also called Wenckebach block), the AV conduction time reflected by the P-R interval (the interval between the onset of the P wave and the QRS complex) on the electrocardiogram (ECG) progressively increases over several heartbeats until an impulse is blocked. This blockage is usually due to a conduction problem in the AV node itself. Mobitz type I block is not usually associated with increased morbidity or death in the absence of other underlying heart disease. Mobitz type I AV block may occur during a heart attack (acute myocardial infarction [AMI]) involving the lower (inferior) surface of the heart. It is associated with various degenerative or infiltrative diseases of the heart, such as amyloidosis and sarcoidosis.

In Mobitz type II the P-R interval remains constant; however, some of the electrical pulses do not reach the ventricles, generally in an intermittent cycle of every second (2:1 block), third (3:1 block) or fourth (4:1 block) P wave. Mobitz type II is a more serious and much less common disorder carrying a high-risk of progression to complete heart block.

Incidence and Prevalence: Mobitz II second-degree AV block is rare in healthy people (˜0.003%). Mobitz I (Wenckebach) occurs more frequently and is observed in 1% to 2% of healthy young people, especially during sleep (Go).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Risk factors include diabetes mellitus, hypertension, heart disease, heart failure, and sleep apnea. Reversible causes of AV block include electrolyte abnormalities, drug-induced AV block, perioperative AV block due to hypothermia, or inflammation near the AV conduction system after surgery in this region (Go).

The cause of Mobitz type II block is an infranodal His-Purkinje system conduction delay, usually from an AMI, and generally results in a wide QRS complex. Other possible causes include pre-existing heart disease, inflammatory diseases (e.g., rheumatoid arthritis), infections, interrupted conduction pathways due to surgery, and scarring. Mobitz type II may be caused by medications used to regulate the heart, such as beta-blockers, calcium channel blockers, and digitalis, as well as metabolic imbalances in the body.

Source: Medical Disability Advisor



Diagnosis

History: Symptoms may not be present with Mobitz type I or Mobitz type II block. However, the individual may report light-headedness, dizziness, and weakness with Mobitz type I block and shortness of breath, chest pain, and palpitations, as well as lightheadedness (presyncope) or fainting (syncope), with Mobitz type II block.

Physical exam: The exam reveals an irregular rhythm at a rate of 50 to 100 beats per minute with Mobitz type I. Mobitz type II AV block may present with a regular rhythm at a rate of 30 to 50 beats per minute. Otherwise, the physical exam is generally unremarkable.

Tests: The ECG confirms second-degree AV block of both types. A portable ECG recorder (Holter recorder) with a 24-hour memory is often used to document the arrhythmia.

Source: Medical Disability Advisor



Treatment

Mobitz type I AV block usually requires no specific treatment. If this type of block is drug-induced, withholding the medication leads to resolution of the AV block. If due to an AMI, the AV block usually resolves spontaneously as the AMI heals.

Treatment is required for a Mobitz type II AV block. A temporary or permanent pacemaker is inserted. Drug therapy is either ineffective or unreliable.

Source: Medical Disability Advisor



Prognosis

Mobitz type I block is usually short-lived. When due to a drug or an inferior AMI, it generally resolves with time (days). However, sometimes it does progress to third-degree AV block (complete heart block). A pacemaker is infrequently necessary because the block is high enough that even if complete heart block occurs, the ventricles continue to beat at a rate of 45 beats per minute or more.

Mobitz type II is usually not short-lived and frequently progresses to complete heart block. A permanent pacemaker is then implanted because the block is lower and the ventricles beat at a rate of fewer than 45 beats per minute. Individuals usually can lead normal lives after pacemaker insertion.

Source: Medical Disability Advisor



Complications

Both Mobitz I and Mobitz II second-degree AV block may progress to third-degree AV block (complete heart block).

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Individuals with Mobitz type I block (not due to an AMI) do not usually require work restrictions or accommodations. Individuals with Mobitz type II block do not usually require any significant work restrictions or accommodations for the conduction problem itself, assuming a permanent pacemaker was installed.

For more information on risk, capacity, and tolerance, refer to "Work Ability and Return to Work," pages 274-277.

Risk: Once stabilized from pacemaker insertion, no job would place an individual at risk except for the presence of strong magnetic fields.

Source: Medical Disability Advisor



Maximum Medical Improvement

30 days.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Does individual complain of symptoms such as light-headedness, weakness, shortness of breath, chest pain, or palpitations?
  • Was an irregular rhythm at a rate of 50 to 100 beats per minute, or a regular rhythm at a rate of 30 to 50 beats per minute (bradycardia) heard?
  • Was a recent electrocardiogram (ECG) done, especially while symptoms were occurring?

Regarding treatment:

  • If the second-degree AV block was drug-induced, was the offending drug discontinued?
  • Did individual undergo implantation of a temporary or permanent pacemaker?

Regarding prognosis:

  • How severe and frequent are the symptoms?
  • Do symptoms interfere with daily activities?

Source: Medical Disability Advisor



References

Cited

Go, A. S. , et al. "Heart Disease and Stroke Statistics--2013 Update: A Report from the American Heart Association." Circulation 127 (2013): e6-e245.

Sovari, Ali A. "Second-Degree Atrioventricular Block." eMedicine. Ed. Jeffrey N. Rottman. 28 Apr. 2014. Medscape. 1 May 2014 <http://emedicine.medscape.com/article/161919-overview>.

Talmage, J. B. , J. M. Melhorn, and M. H. Hyman, eds. Work Ability and Return to Work, AMA Guides to the Evaluation of. Second ed. Chicago: AMA Press, 2011.

Source: Medical Disability Advisor






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