EKG Week 1

Coronary Arteries
Autonomic Nervous System (ANS)
• Located at the base of aorta, supply heart with O 2
• Coronary arteries fill during diastole when vascular
resistance is lower
• Need DBP of 60 or > to perfuse coronary arteries
• Right coronary artery (RCA)
– Supplies AV Node, SA node (50% of pop), & HB
• Left coronary artery (LCA)
– Left Anterior Decending (LAD)
– Left Circumflex (LC)
– Supplies SA node (50% of pop), BBs, & Purkinje
fibers
Sympathetic (Û)
• Accelerates
• β 1 receptor sites
• Epi/Norepinephrine
• Stimulation results:
– Û contraction
– Û conduction
– Û CO, HR, BP
Parasympathetic (Ü)
• Inhibits
• Vagus nerve
• Acetylcholine
• Stimulation results:
– Ü HR (SA node)
– Ü AV conduction
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Cardiac Output (CO)
S/Sx of Decreased CO
• CO = SV (stroke volume) X HR (heart rate)
• CO = amount of blood ejected (pumped) by
the ventricles in 1 minute (LPM)
• Normal adult CO = 4-8 LPM
• SV = amount of blood ejected by ventricles w/
each contraction - 1 heartbeat = 70 ml/beat
• CO is affected by a change in HRÓ
or Ô, or stroke volume Ó or Ô
• Cold, clammy skin
• Color changes in skin
or membranes
• Dyspnea
• Orthopnea
• Crackles (rales)
• Restlessness
• Changes in mental
status
• Changes in BP
• Dysrhythmias
• JVD
• Fatigue
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