Sinus Rhythms

Question 1

SINUS BRADYCARDIA identify the:
- conduction problem
- cause
- implications for O2 supply and demand
- interventions

Answer 1

• Conduction Problem: impulse formation at SA node but firing slower than normal
• Cause: normal in athletes; if taking digoxin; decrease in myocardial O2 consumption
• abnormal is drug OD, MI, hypoxia, hypothermia, electrolyte imbalances
• Implications: slow HR decreases CO.
• Interventions: check your pt, ABCs, signs of decreased CO (dec LOC, hypoTN, chest pain, SOB). may need atropine or temporary pacemaker

Question 2

what is the heart rate range for sinus tachycardia (ST)?

Answer 2

100-150bpm, max is 180bpm

Question 3

SINUS TACHYCARDIA identify the:
- conduction problem
- cause
- implications for O2 supply and demand
- interventions

Answer 3

• Conduction Problem: site of impulse formation is at SA node, which is experiencing enhanced automaticity
• Cause: normal = SNS stimulation in exercise, stimulant drugs
• abnormal = fever, hypoxia, hypovolemia, MI, anxiety, pain
• Implications: increased HR = increased O2 demand, decreased VFT = decr preload and stroke volume; decr coronary artery filling time = decr contractility and CO
  *in some individuals who are healthy, sinus tachycardia may be normal
• Interventions: check your pt (ABCs). ax for signs of decreased CO. correct the cause.

Question 4

what is sinus arrythmia often related to?

Answer 4

resp patterns; increased HR when breathing in, decreased HR when breathing out d/t changes in intrathoracic pressure

Question 5

can sinus arrythmia be normal?

Answer 5

cause is normal in young children

Question 6

what can sinus arrest be terminated by?

Answer 6

• a normal sinus beat
• a junctional escape beat or ventricular escape beat

Question 7

what is the difference about P waves in sinus arrest versus sinoatrial exit block?

Answer 7

in sinus arrest, the P waves don’t all match up whereas in sinoatrial exit block, the P waves all match up even with the pause

Question 8

what is similar about the arrest or block in terms of implications to O2 supply and demand?

Answer 8

if its prolonged, there will be decreased cardiac output, decreased HR and decreased O2 supply

Question 9

what is the rhythm in sinus arrest?

Answer 9

irregular d/t arrest or underlying regular

Question 10

what is the conduction problem in sinus arrest?

Answer 10

when the SA node fires there is no conduction problem. but when it does not fire that is when problems arise. sinus arrest could cause HR to be so slow that hemodynamic status is compromised. if arrest is long enough, a secondary pacemaker from AV junction or purkinje fibers in ventricle may have to take over to provide some CO

Question 11

causes of sinus arrest

Answer 11

• hypoxia
• hypothermia
• drug toxicity
• vagal stimulation
• electrolyte imbalance
• cardiac ischemia

Question 12

interventions for sinus arrest

Answer 12

atropine or temporary pacemaker

Question 13

what is the rhythm in SA exit block?

Answer 13

irregular d/t SA blocks

Question 14

what is the conduction problem in SA exit block?

Answer 14

site of impulse formation is SA node, but some impulses are blocked from depolarizing atria, affecting conduction (no P wave)

Question 15

what is the cause of SA exit block?

Answer 15

cardiac ischemia

Question 16

what are implications to O2 supply and demand and interventions for SA exit block?

Answer 16

• with a prolonged block, the heart rate will decrease and therefore decrease CO.
• Assess the patient-ABCs. intervention will depend on the impact on the pt’s CO

Question 17

what are the implications for O2 supply and demand for sinus arrest?

Answer 17

if this dysrhythmia is transient and the patient is not symptomatic, then there may be no CO or O2 supply implications. If the dysrhythmia is frequent or prolonged, CO will be affected because of a loss of heartbeats.