Arrhythmias Flashcards
Whats is flutter?
When contractions are very rapid, but coordinated; can live
What is fibrillation?
When contraction of myocardial cells occurs at different times
Coordinated pumping is impossible
What is the outlook of Afib? Vfib?
In atria, survivable→ 80% of filling occurs before atrial contraction
In ventricle, fatal
What is going on with a problem in the P-Q area?
A delay of action potential through atrium
What are 4 causes of P-Q problems?
Scar tissue (impedes SA-AV information)
Ischemia (in atria)
Dilated atrium, delays action potential, causing arrhythmia
Compression or necrosis of AV node
What is going on with a problem in the Q-T area?
Delay of action potential through ventricles
What are 2 causes of Q-T problems?
eg MI- Sudden death of a patch of myocardial cells
eg Abnormally large ventricle (delays signal)
What is the cardiac cycle? What are the 2 phases?
Includes all events associated with the flow of blood through the heart during one heartbeat
Systole- Contraction
Diastole- Relaxation
What is systole? What does the heart do? What happens to BP?
Contraction
Chamber contracts and pushes blood into adjacent chamber
Pressure rises during systole
What is diastole? What does the heart do? What happens to BP?
Relaxation
Chamber relaxes and fills with blood
Pressure falls
What is EDV? What does it mean?
End-diastolic volume- Total volume of blood in the ventricle at the end of diastole
120 ml, the maximum amount of blood the heart can hold in this cycle
What is ESV? What does it mean?
End-systolic volume- Total volume of blood in the ventricle at the end of systole
50 ml - Ventricles do not completely empty, there’s some blood left
What is stroke volume?
Volume of blood pumped out of a ventricle during each beat or cardiac cycle- 70 ml
How is stroke volume determined?
EDV-ESV= Stroke Volume 120-50= 70 ml
What is cardiac output?
The volume of blood pumped per minute by each ventricle
What two things impact cardiac output?
↑ Blood Viscosity
↓ Peripheral resistance
What can increase blood viscosity?
↑ RBCs or dehydration (not proteins)
What can lower peripheral resistance?
Degree of arteriolar vasoconstriction, blood can’t flow as easily into capillaries
When you auscultate, what do you actually hear?
The closing of valves is silent, you actually hear the turbulence of moving blood
In the lubb-dupp of the heart, what makes the sounds?
Lubb- Closing of AV valves
Dupp- Closing of SL valves
What is isovolumetric contraction?
AV valves are closed, but theres not enough pressure yet to open the SL valves. So, there’s and ↑ in pressure in the (closed) ventricle, while all valves are closed.
What is isovolumetric relaxation?
Both valves are closed again, the ventricles are relaxing, but still too much pressure in ventricle for atria to send blood in. Ventricle is relaxing, but the volume (50 ml) doesn’t change.
What is a heart murmur? A cause?
Abnormal heart sounds produced by abnormal patterns of blood flow.
eg cusps not closing properly
Can the heart sustain contraction?
No, it’s a pump.
What 4 processes control HR?
Intrinsic Control
Extrinsic Control
Hormonal Control
Extracellular ion concentration
What is the law for intrinsic control of the heart?
Frank-Starling Law
What does the Frank-Starling law state?
“More in, more out” - The stretching of a ventricle causes that ventricle to contract more forcefully to expel additional blood, maintaining cardiac output
How does the Autonomic nervous system impact HR?
Which cranial nerve is used?
Sympathetic ↑HR; Parasympathetic ↓HR (via vagus X nerve)
What ANS sensors impact HR? Where are they found?
Baroreceptors (pressure) and Chemoreceptors (O2 &CO2) both found in the aortic arch and carotid sinus
How does hormonal control impact HR and BP?
It raises and only raises, both
Which 5 hormones control HR and BP?
Epi/NE
ADH
Aldosterone
Angiotensin II
