Cardiothoracics Flashcards
(105 cards)
What causes a valve to open?
Pressure in greater in the given chamber in comparison to the next chamber or artery.
What are septal defects?
A whole in the heart, reducing the efficiency of the heart.
Can cause long-term structural changes due to pressure changes and resulting hypertrophy (to make up for changes in pressure)
Can be atrial or ventricular
What are calcification of valves and what do they cause?
Calcium build up on the valves of the heart.
Common, especially in elderly
Valve may not close properly, which will allow backflow of blood during diastole.
Can cause hypertrophy as heart has to work harder
What are the heart sounds you listen to within the heart?
1st is AV valves closing, ventricular pressure would then increase. Should just hear one sound as the two valves should close at the same time.
2nd sound is the pulmonary and aortic valves closing. Should be one sound as they close at the same time.
What are Korotkoff sounds?
Sound of turbulent blood flow, related to taking blood pressure
What controls blood flow?
Valves opening and shutting
What way do ventricles contract?
From the apex of the heart so they can push blood in the correct direction
What is the stroke volume of the heart?
Amount ejected per beat
How can you increase the stroke volume of the heart?
Strenuous activity increases contractility which will increase amount being ejected as well as increasing heart rate
How do you calculate cardiac output?
Stroke volume x Heart rate per minute
Stroke volume normally ~5L/min
Each side pumps about 5L
What is Starling’s law?
The more you stretch the heart, the harder it contracts
What determines the heart rate?
SA Node
Wants to work at 100bpm, but it is kept under control
What does the AV node do?
It slows conduction and can act as secondary pacemaker
What causes fibrillation?
SA node??
Lack of equal conduction to either side of heart, no coordination
Ventricular fibrillation will kill you
What does an ECG do?
Detects phasic changes in potential difference between two electrodes
Allows you to track heart rhythm and electrical activity
What does a P wave measure
Atrial depolarization
What does the QRS complex measure?
Ventricular depolarization
this is when they should start to contract
What does the T wave measure?
Ventricular repolarization
What does an ECG NOT tell you?
Does not tell you how well the heart is contracting
Why dont we see atrial repolarization?
It is hidden by the QRS complex
What is the PR interval indicating?
A delay in electrical transmission through the AV node
What does the ST segment represent, and how can it be used in diagnosis?
The time between depolarization and repolarization of the ventricles.
Important in diagnosing myocardial ischemia
What does the R-R interval on an ECG measure?
Time between heart beats
Can indicatin brady/tachycardia
What phase (0-4) of cellular action potential is represented by the ST segment?
Phase 2- inward movement of calcium leading to the plateau phase (balance of Ca and K movement), seen as the ST segment (i.e. may change in patients with an MI)
Refractory period stops us from continually activating the heart, and is the plateau phase
Important in diagnosing myocardial ischemia (it is changed, and can be depressed or elevated on an ECG in comparison to the PR segment)