EKG: Sinus Node Related Dysrhythmias

Dysrhythmias occur in patients for many different reasons. Although a myocardial infarction (MI) is one of the most common reasons for abnormal heart beats to arise, many other disease processes and injuries can also precipitate rhythms that do not provide for the best cardiac output. Etiologies of Dysrhythmias lists some of the etiologies of dysrhythmias.

Contents

Sinus Node Related Dysrhythmias: Etiologies of Dysrhythmias

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

Health care providers must be ready to interpret these rhythm disturbances and intervene appropriately. Some dysrhythmias are dysfunctional causing interruptions in normal vital signs. Some dysrhythmias are benign and though they may make the patient feel uncomfortable, are not dangerous. Some dysrhythmias are incidental and the patient may not even be aware of it. Some dysrhythmias are beneficial and must be present in order for the patient to survive. Some dysrhythmias are fatal and require life-saving interventions. Symptoms that patients may present with when experiencing a dysrhythmia are listed in Symptoms Associated With Dysrhythmias.

Sinus Node Related Dysrhythmias: Symptoms Associated With Dysrhythmias

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

Clinical Alert

A common sign, especially with faster rhythms, is a feeling or perception of the heartbeat. These palpitations may feel like their heart is beating fast or the patient may describe either a fluttering type of sensation in the chest or the feeling of missed or extra beats. These palpitations can also create anxiety which can contribute to the patient’s feeling of impending doom.

Dysrhythmias (also known in medical terminology as arrhythmias) occur whenever there is an interruption or disruption in the rate, regularity, originating impulse, or conduction of that impulse. These can appear as a single or occasional extra beat, as a prolonged rhythm that the patient maintains for a period of time (or their lifetime) or which may recur intermittently for particular patients throughout their life span, or as a significant acute crisis that can precede sudden death.

This chapter will begin the discussion of dysrhythmias with a glimpse into those rhythms that are sinus in origin.

Sinus Node Related Dysrhythmias: Sinus Rhythms

Focus topic: Sinus Node Related Dysrhythmias

Normal sinus rhythm is the most common rhythm and is not a dysrhythmia at all. This is the standard by which all other rhythms are judged.

Sinus Node Related Dysrhythmias: Sinus Bradycardia

Focus topic: Sinus Node Related Dysrhythmias

Bradycardia means a slow heart rate (HR). When sinus bradycardia (SB) is present, the SA node is still the pacemaker for this rhythm, but it is discharging at a much slower rate than normal. Conduction of the impulse follows the usual pathway. Sinus bradycardia may naturally be present in healthy adults during sleep. It can also be a common presentation in athletes. When examined, the rhythm strip will basically have all the same features as normal sinus rhythm except the rate.

The following will be typical EKG characteristics for sinus bradycardia (Sinus bradycardia):

  • Regularity: Regular rhythm
  • Rate: Less than 60 beats per minute
  • P wave: Present for each QRS complex
  • PR interval: 0.12 to 0.20 seconds
  • QRS complex: Less than 0.10 seconds in width
  • QT interval: May be longer due to slower rate
  • T wave: Normal configuration and size
  • ST segment: Normal configuration and size

Sinus Node Related Dysrhythmias: Sinus bradycardia

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

Sinus bradycardia can frequently occur with an inferior or posterior MI. Another etiology of this slow rate is that of vagal stimulation. When the vagus nerve is stimulated, which can occur with cough, straining, vomiting, or extended standing positions, bradycardia can manifest due to the relationship of the vagus nerve to the parasympathetic nervous system. When the vagus nerve is stimulated, the heart rate will slow or become bradycardic. When patients have some types of fast heart rates, vagal stimulation is often used in an attempt to decrease the pulse. This can be done by having the patient cough, hold their breath and push downward as if having a bowel movement (Valsalva maneuver), or placing their face in ice cold water. Stimulation of the carotid artery will also slow the heart rate and produce this dysrhythmia. These treatment options for fast heart rates are performed by the physician or other mid-level provider. Causes of Sinus Bradycardia lists some causes of sinus bradycardia.

Sinus Node Related Dysrhythmias: Causes of Sinus Bradycardia

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

Clinical Alert

Patients who are on beta-blocker medications will often have bradycardic rhythms when the health care provider would expect the heart rate to be fast such as in hypovolemic shock. Beta-blockers keep the heart rate slow in these patients. It is important for the health care provider to be aware of medications patients are taking during assessment.

If the patient is not having any symptoms (asymptomatic), no immediate interventions are necessary. Symptomatic bradycardia may need to be treated with the administration of atropine which should increase the heart rate. When patients have a low pulse rate, the only way to improve cardiac output (CO) is to increase the stroke volume (SV) (CO = SV × HR). With many patients, this may not be an option. Atropine improves not only the rate at which the SA node is firing, but also strengthens the conduction of the impulse. A pacemaker may also be required. If the patient has a very low pulse rate, that is, 30 to 40 beats per minute, but is tolerating the low heart rate as evidenced by normal blood pressure, no chest pain, no dizziness or other symptomatology, a pacemaker may still be necessary, but is not emergent. As stated in previous chapters, treat the patient, not the machine. Low heart rates associated with an acute MI may actually be advantageous since it can reduce the oxygen requirements for the heart at that time. Always provide oxygen and make sure that a patent intravenous line is in place when patients display low heart rates.

Clinical Alert

Infants normally have a faster heartbeat. An infant with a heart rate less than 90 to 100 is considered to be bradycardic. Very sick infants or children presenting with bradycardia is an ominous sign. When children attempt to compensate for low cardiac output, they speed the heart rate up as they have a fixed SV. Inability to compensate in this way is a dangerous pattern.

Sinus Node Related Dysrhythmias: Sinus Tachycardia

Focus topic: Sinus Node Related Dysrhythmias

Sinus tachycardia (ST) occurs when the SA node sends impulses at a faster than normal rate. Tachycardia is recognized at rates greater than 100 beats per minute. Other tachycardias can also be present, but these have foci or impulse generating tissue other than the SA node. Sinus tachycardia can be exhibited in otherwise normal, healthy adults when experiencing anxiety or stress. It can also occur as a response to a disease state such as hemorrhage, pain, a hyperthyroid state, a pulmonary embolus, or other pathologic disorders. When this is present, patients may state that they have a “pounding” feeling in the chest region or may feel like their heart is racing. A radial pulse with very fast heart rates may feel weak and thready to the health care provider. The following list features characteristics of sinus tachycardia as seen on a cardiac monitor or 12-lead EKG (Sinus tachycardia):

Sinus Node Related Dysrhythmias: Sinus tachycardia

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

 

  • Regularity: Regular rhythm
  • Rate: Greater than 100 beats per minute (under 180 beats per minute)
  • P wave: Present for each QRS complex (may be difficult to distinguish P waves from T waves in extremely rapid rates)
  • PR interval: 0.12 to 0.20 seconds (may be shorter in faster rhythms)
  • QRS complex: Less than 0.10 seconds in width
  • QT interval: May be shorter due to faster rate
  • T wave: Normal configuration and size
  • ST segment: Normal configuration and size

Sinus tachycardia can occur as a reaction to any demand on the body for increased oxygenation. When the heart beats faster, the ventricles do not have time to fill adequately. This then reduces the amount of blood that is available to be delivered to the lungs and the body during contraction of the ventricles, which in turn equates to a decrease in cardiac output. This decrease in cardiac output may be seen through a decline in the blood pressure and reduced oxygenation of the periphery since perfusion has dropped. Coronary arteries are also filling at a reduced rate due to the decrease in diastolic time. Normally this is the time that the coronary arteries are receiving their burst of blood flow. Patients may complain of chest pain due to the insufficient oxygenation of the heart muscle itself. While many tachycardic rhythms can be easily explained and treated, tachycardias associated with MIs can be an early sign of impending cardiogenic shock or heart failure.

Etiologies of Sinus Tachycardia provides a listing of etiologies of sinus tachycardia.

Determining proper treatment for sinus tachycardia is aimed at identifying the underlying cause and treating this causative factor appropriately. It may require something as simple as providing medications to alleviate anxiety until the basis for the anxious reaction can be corrected. Resting after exercise will reduce the heart rate back to a normal rate. Other therapeutic regimens that may be required could include fluid and electrolyte replacement, stop active internal or external bleeding, pain relief, temperature control, discontinuance of medications or street drugs that increase heart rates such as cocaine, amphetamines, or “bath salts”, decrease intake of caffeine or nicotine, or cessation of alcohol intake. If the tachycardia is producing negative cardiac output symptoms such as hypotension or a decreased level of consciousness, medications such as beta-blockers (Metoprolol [Lopressor], Atenolol [Tenormin], Diltiazem [Cardizem], Labetalol [Normodyne]) may be used to bring the heart rate into a normal rate. Symptoms of heart failure such as increased jugular venous distention or crackles during auscultation of lung sounds may preclude the use of these medications.

Sinus Node Related Dysrhythmias: Etiologies of Sinus Tachycardia

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

Clinical Alert

Children respond to illness by increasing their heart rate. As stated previously, the two factors that create cardiac output are stroke volume and heart rate. Children, including infants, will increase their heart rate in an attempt to increase their cardiac output when circumstances arise that place them at risk. This occurs because children and infants are unable to change their stroke volume. This fixed stroke volume will cause them to respond to perceived or real threats by increasing the heart rate in an attempt to increase cardiac output. This is an important concept to keep in mind when caring for children. This normal compensatory response to disease states such as dehydration and fever, as well as anxiety and fear of strangers, coupled with the fact that children and infants normally have higher pulse rates, can be considered to be “normal” and therefore, health care professionals should be careful to not become complacent about these high pulse rates in the pediatric population. Increased heart rates in the absence of fever or other disease situations should alert the health care professional to an underlying problem that often requires intense exploration. A toddler with a heart rate of 180 with no fever or distinguishable reason for the tachycardia demands diagnostic attention. A heart rate of 200 beats per minute in an infant and 160 beats per minute in a child under age 5 is considered to be tachycardia.

Sinus Node Related Dysrhythmias: Sinus Arrhythmia

Focus topic: Sinus Node Related Dysrhythmias

Sinus arrhythmia is a rhythm which can be normal for particular populations. This is a normal phenomenon in children and some adults up to the age of 30 that is usually associated with respirations. During inspiration the heart rate increases and during the expiratory phase of breathing, the heart rate decreases. Changes in intrathoracic pressure that affects the vagus nerve is the etiology of this type of sinus arrhythmia. The vagus nerve, which is part of the parasympathetic nervous system, reduces its tone during the inspiratory stage of the respiratory cycle due to an increase in the amount of blood flow returning to the heart. This allows for an increase in pulse rate. During expiration, this return decreases and allows the vagal tone to increase causing a decrease in pulse rate. Having the patient hold their breath will cause their rhythm to return to a regular pattern during that time.

Another type of sinus arrhythmia, nonrespiratory sinus arrhythmia, may occur in older adults due to the normal aging process, the presence of an acute inferior MI, the use of medications such as morphine or digoxin (Lanoxin), or an increase in intracranial pressure. A patient receiving digoxin (Lanoxin) who suddenly develops this dysrhythmia should be considered as a potential candidate for digitalis toxicity. Be sure to notify the patient’s provider if this dysrhythmia suddenly appears.

In this type of dysrhythmia, all aspects are normal except for the irregularity which takes place. When discussing the rate, it may be recorded as a range, such as “sinus arrhythmia at 52 to 78 beats per minute” (Sinus arrhythmia).

Sinus Node Related Dysrhythmias: Sinus arrhythmia

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

 

  • QT interval: Normal length, may vary slightly
  • T wave: Normal configuration and size
  • ST segment: Normal configuration and size

Sinus arrhythmia usually does not require treatment. However, in cases of sudden onset, do consider the causes as listed above.

Clinical Alert

Be sure to correctly identify sinus arrhythmia. This may require a longer than usual observation of the cardiac monitor. A longer rhythm strip may be necessary to determine that it is not a different rhythm such as atrial fibrillation, premature atrial contractions, a block of some type, or sinus pauses. Watch to see that the breathing pattern is in concert with the rates on the rhythm strip or cardiac monitor. Another type of serious sinus dysrhythmia can occur in older adults known as sick sinus syndrome. In this case there is wide variation of the P-P intervals.

Sinus Node Related Dysrhythmias: Sinus Arrest

focus topic: Sinus Node Related Dysrhythmias

Sinus arrest occurs when the SA node fails to produce an electrical impulse. Other names for this dysrhythmia are atrial standstill, sinus pause, and sinoatrial arrest. In this disease process, the SA node fails and no PQRST complex or contraction is created. The term sinus arrest is usually used when three or more beats are omitted from the rhythm strip. The EKG tracing or cardiac monitor will have normal appearance except that complete PQRST complexes are missing (Sinus Arrest).

  • Regularity: Irregular rhythm—however it can be called regular except for the event of the missing PQRST complexes
  • Rate: Usually normal will vary due to the loss of complexes
  • P wave: Present for each QRS complex that is present
  • PR interval: 0.12 to 0.20 seconds and constant with each beat present
  • QRS complex: Less than 0.10 seconds in width and constant with each beat present
  • QT interval: Normal length
  • T wave: Normal configuration and size when present
  • ST segment: Normal configuration and size when present

Sinus Node Related Dysrhythmias: Sinus Arrest

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

 

In the absence of the impulse from the normal pacemaker site, other sites such as the AV junction or ventricular tissue may produce an impulse in an attempt to rescue the situation; however, this does not always happen. When these areas of the heart attempt to assist, a junctional or ventricular beat will occur on the EKG tracing or cardiac monitor at some point in the arrest period. These escape beats are essential to the patient’s heartbeat at this time (Sinus arrest with ventricular escape beat).

Sinus Node Related Dysrhythmias: Sinus arrest with ventricular escape beat

Sinus Node Related Dysrhythmias

 

Focus topic: Sinus Node Related Dysrhythmias

Patients who are experiencing occasional sinus arrests or pauses may be asymptomatic. These require no immediate treatment except for determining the cause and properly treating the process. If these events occur during sleep, they may not have significant value. However, if these episodes become more numerous or are repeated and prolonged, the patient may complain of generalized weakness, dizziness, light-headedness, or may describe syncopal episodes. Immediate treatment may be necessary for these prolonged or frequent incidents. A prolonged episode of sinus arrest will constitute asystole. Proper treatment may include administration of epinephrine and the implantation of an emergent temporary pacemaker. A permanent pacemaker may then be required once the etiology of the sinus arrest has been determined. Escape beats such as junctional or ventricular complexes as described above are not treated at this time. Increasing the heart rate is the treatment of choice. Once the heart rate is improved, these escape beats will not be necessary and they will cease. Causes of sinus arrest or pause are outlined in Causes of Sinus Arrest.

Sinus Node Related Dysrhythmias: Causes of Sinus Arrest

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

Clinical Alert

Patients who are having prolonged or multiple recurrences of sinus arrest will not have a radial pulse during the time of the event. Observing the rhythm on the cardiac monitor while physically assessing the patient during the incident will assist the health care provider in identifying and properly treating the patient. This type of patient may also exhibit hypotension, mentation changes, cool, clammy skin, dizziness, blurred vision, lightheadedness, and/or a general feeling of weakness. Sometimes the health care provider needs to be a detective of sorts because the patient may be present for evaluation for other reasons including seizures, motor vehicle crashes, or falls. Including family members or significant others in the history taking portion of an assessment may provide insight into the event of which the patient is unaware.

Sinus Node Related Dysrhythmias: Sinoatrial Blocks

Focus topic: Sinus Node Related Dysrhythmias

Sinoatrial blocks are similar to sinus arrest and pause. Some authors relate difficulty in differentiating the two types of rhythms. One of the main differences between these dysrhythmias is the underlying problem. In sinus arrest or pause, there is a problem with automaticity, that is, the SA node fails to begin the process of electrical stimulation by simply not initiating an impulse. Sinoatrial blocks occur due to a problem with conductivity, that is, the impulse is there, but it cannot get through to the transitional cells to complete its task. In reality, it is difficult to discriminate between the two sinus problems.

There are four types of SA blocks. These subcategories are based on the length of the delay in conduction. In SA block, the impulse is being generated, but the EKG tracings and cardiac monitors do not display the actual SA node activity. Therefore, what is considered to be SA block type I cannot be detected by EKG. SA block type II is further subdivided into second-degree type I and second-degree type II. Second-degree type I SA block is noted when the P-P intervals of the preceding PQRST complexes become shorter and shorter before the actual beat is dropped (Second-degree SA block type I).

Sinus Node Related Dysrhythmias: Second-degree SA block type I

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

 

In second degree SA block type II there is no difference in the P-P intervals preceding the dropped complex. The measure of the area of the dropped complex between the two P waves is an exact multiple of the P-P intervals that are present in the underlying rhythm (Second-degree SA block type II).

Sinus Node Related Dysrhythmias: Second-degree SA block type II

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

 

In third-degree SA block the P-P intervals preceding the dropped complex are equal. The pause that occurs with this type of SA block is not an exact multiple of the P-P intervals. The greatest clue to this rhythm is that the pause itself ends with a sinus beat whereas sinus arrest will often end with either a junctional or ventricular escape beat (Third-degree SA block).

Sinus Node Related Dysrhythmias: Third-degree SA block

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

 

Etiologies, treatment, and concerns regarding SA block are the same as for sinus arrest. The major difference with these two dysrhythmias is that SA block is a problem of conductivity and sinus arrest or pause is a problem with automaticity. In SA block the impulses are being formed, but they are blocked from the rest of the tissue. With sinus arrest, no impulses are being generated.

Clinical Alert

It is important to remember that the SA node blocks are different than the AV node blocks, which can cause emergent issues for patients.

Sinus Node Related Dysrhythmias: Sick Sinus Syndrome

Focus topic: Sinus Node Related Dysrhythmias

Sick sinus syndrome is also known as sinus nodal dysfunction and brady-tachy syndrome. A combination of both conductivity and automaticity occur with this syndrome. It usually is present in older adults (>age 60) and can occur in children who have had open heart surgical procedures in which the SA node sustained damage. Although occurrences with complications from sick sinus syndrome can occur acutely, the disease itself develops over a period of time and becomes a chronic, progressive debilitating disease.

Destruction of the node itself from situations that lead toward fibrosis such as hypertension, cardiomyopathy, atherosclerosis, and the normal aging process can be the cause of this dysfunction. Other major etiologies include direct trauma to the SA node (pericarditis, open heart surgery, rheumatic fever that leads to rheumatic heart disease), problems with the autonomic nervous system, and medications such as beta-blockers, digoxin (Lanoxin), and calcium channel blockers. Any condition that triggers atrial tissue to become inflamed or to deteriorate is a potential source.

When a patient presents with sick sinus syndrome, any of several dysrhythmias can occur. Often there is a combination of two or more. The most frequent include the following:

  • Sinus bradycardia
  • Sinus arrest/Sinus pause
  • Alternating Bradycardia/Tachycardia of sinus node etiology
  • Atrial fibrillation/Atrial flutter

Since such a variety of rhythms can occur with this difficult diagnosis, it is impossible to note standard measurements or configurations for EKG tracings or cardiac monitor strips. The alternating bradycardic and tachycardic rhythms are classic in this patient. Typical rhythm strip for sick sinus syndrome is a typical strip for this patient.

Sinus Node Related Dysrhythmias: Typical rhythm strip for sick sinus syndrome

Focus topic: Sinus Node Related Dysrhythmias

Sinus Node Related Dysrhythmias

Patients with this disorder may present with signs of heart failure including crackles in the lungs and an S3 sound. They may also have a fluttering feeling in their chest, syncopal or near syncopal episodes, hypotension, chest pain, shortness of breath which worsens with exertion, blurred vision, and varying heart rates noted both on the cardiac monitor and by physically checking the radial pulse. Another interesting symptom that may occur is that the pulse does not increase with exercise and there is no other identified cause for this such as medications that the patient may be taking.

Asymptomatic patients may not require therapeutic regimens. Treatment for sick sinus syndrome is targeted at the underlying cause of the problem. If the patient is symptomatic, interventions should be provided that are directed at relief of these symptoms such as hypotension. Sometimes treating the tachyarrhythmia is counterproductive and can actually worsen the syndrome. Anticoagulants may be prescribed for the atrial fibrillation or flutter that represents the tachycardic portion of the disorder. The bradycardia may need to be treated with atropine or epinephrine. A temporary and subsequent permanent pacemaker is often used.

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Sinus Node Related Dysrhythmias: Conclusion

Focus topic: Sinus Node Related Dysrhythmias

Sinus node dysrhythmias include sinus bradycardia, sinus tachycardia, sinus arrhythmia, sinus arrest and pauses, SA node blocks, and sick sinus syndrome. Each of these abnormal heart rhythms has its own distinguishing characteristics, symptoms, and treatment regimens. Often when patients are asymptomatic, no treatment is necessary. Some of the important aspects of this chapter are as follows:

  • Dysrhythmias occur for many different reasons.
  • Some dysrhythmias are benign and do not cause symptoms.
  • Some dysrhythmias can be fatal if interventions are not begun immediately.
  • Symptoms that patients may have include chest pain, palpitations, vomiting, anxiety, cold, clammy skin, arm and jaw pain, syncope, blurred vision, and sudden death.
  • A perception of the heartbeat is called palpitations.
  • Dysrhythmias are caused by disruptions of rate, regularity, originating impulse, or conduction of the impulse.
  • The most common rhythm is normal sinus rhythm. All other rhythms are judged off of this rhythm.
  • Sinus bradycardia is a slow heart rate that is below 60 beats per minute.
  • All other aspects of the rhythm in sinus bradycardia are normal except for the rate.
  • An inferior of posterior MI is associated with a bradycardic rhythm.
  • Vagal stimulation will cause a slow heart rate.
  • The vagus nerve is part of the parasympathetic nervous system.
  • Coughing, straining, or vomiting can cause stimulation of the vagus nerve.
  • Vagal stimulation is often performed on purpose to decrease fast heart rates.
  • Atropine is one drug that can be used for symptomatic bradycardia.
  • A pacemaker is a viable option for treatment of symptomatic bradycardia.
  • An asymptomatic patent with sinus bradycardia often does not need treatment or may have a pacemaker placed on a scheduled, rather than emergent, basis.
  • Bradycardia in an infant or child is an ominous sign.
  • Sinus tachycardia occurs when the heart rate is over 100 beats per minute and all other parameters are normal.
  • One of the most common causes of sinus tachycardia is anxiety.
  • Some other etiologies of sinus tachycardia include hemorrhage, pain, hyperthyroidism, and pulmonary embolus.
  • A patient with a very fast heart rate will have a weak and thready radial pulse.
  • Sinus tachycardia can create a situation of decreased cardiac output.
  • When cardiac output drops, this may be manifested by a low blood pressure and reduced peripheral oxygenation.
  • Sinus tachycardia associated with an acute MI may be a sign of impending heart failure or cardiogenic shock.
  • Patients with sinus tachycardia may need anti-anxiety medications, but also may require fluid replacement, cessation of bleeding, pain relief, temperature control, or the discontinuance of certain medications or street drugs.
  • One of the first ways that children compensate for problems in the body is to increase the heart rate.
  • Health care providers need to remember that even though children and infants normally have high heart rates, they should be cognizant of the fact that tachycardias do exist for these age groups and need to be recognized and treated seriously.
  • Sinus arrhythmia is a normal cardiac response for children and for some adults up to age 30.
  • Changes in heart rate associated with sinus arrhythmia are related to inspiration and expiration.
  • Sinus arrhythmia has an irregular pattern. All other parameters are normal.
  • Observe the cardiac monitor or the EKG tracing for a long period of time when interpreting the rhythm as sinus arrhythmia.
  • Sinus arrest occurs when the SA node does not create an impulse.
  • Sinus pause occurs when one to two complexes are lost. Sinus arrest is identified when there are three or more lost complexes in a row.
  • Escape beats may occur from other cardiac tissue when sinus arrest occurs.
  • Some patients with sinus pause or arrest may be asymptomatic.
  • Other patients with sinus pause or arrest may have symptoms of lightheadedness or syncopal episodes.
  • An emergent or planned pacemaker may be necessary to treat patients with sinus arrest.
  • Patients may present with other chief complaints such as falls or seizures when they are actually having episodes of sinus arrest or sinus pause.
  • SA blocks exist but are difficult to interpret through the cardiac monitor or EKG tracing.
  • Four SA blocks are listed in the literature, but SA block type I is not able to be distinguished from sinus arrest or pauses.
  • The problem with sinus arrest or pauses has to do with a lack of automaticity.
  • The problem with SA blocks is a lack of conductivity.
  • Second-degree SA block type I is interpreted when there is a dropped complex and the previous beats have shorter and shorter P-P intervals.
  • Second-degree SA block type II is seen when the P-P intervals are the same, but the period of time from the last complex before the dropped complex to the next complete complex is an exact multiple of the P-P interval.
  • Third-degree SA block ends the dropped sinus beat period with a sinus beat.
  • Sick sinus syndrome presents with a variety of dysrhythmias including sinus bradycardia, sinus arrest, sinus pause, atrial fibrillation, atrial flutter or an alternating bradycardia/tachycardia.
  • Another name for sick sinus syndrome is brady-tachy syndrome.
  • Sick sinus syndrome occurs due to destruction of the SA node.
  • No standard measurements or configurations are manifested with sick sinus syndrome.
  • Treating the cause of the problem is the main treatment regimen for sick sinus syndrome.
  • Treating the tachyarrhythmia in sick sinus syndrome can be counterproductive.
  • A pacemaker is the usual treatment of choice for sick sinus syndrome.
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