CVS 12 Shock, Review and Hypertension Flashcards
What can cause poor regional perfusion?
arterial occlusion- peripheral artery disease, coronary artery disease
venous congestion- varicose veins, DVT
In which direction do veins drain?
Superficial to deep
What constitutes a positive exercise stress test for ischaemic heart disease?
If there is chest discomfort or ECG changes
What ECG abnormality is seen in angina?
ST segment depression
What is stable angina treated with?
Nitrates
Beta- blockers
Calcium channel antagonists
What is the principle action of nitrates in angina relief?
Venodilation causing decreased preload to heart to reduce workload
What abnormalities are see in an ECG with unstable angina?
ST depression and/or T wave inversion
What ECG changes are seen with a STEMI?
ST elevation
T wave inversion
Pathological Q waves
What feature of a STEMI ECG persists even weeks after recovery?
Pathological Q waves
What is troponin and which isoforms are used to detect MI?
Regulatory protein that is bound on tropomysosin, involved in muscle contraction
Troponin I and Troponin T
What is cardiac arrest?
Unresponsiveness associated with lack of pulse
Heart has either stopped or ceased to pump effectively
What is asystole?
Loss of electrical and mechanical activity
What is the most common form of cardiac arrest and when does it occur?
Ventricular fibrillation
May occur following MI or electrolyte imbalance or some arrhythmias (e.g long QT and Torsades de Pointes)
What is pulseless electrical activity?
Form of cardiac arrest where ECG looks normal but there is no pulse
What basic life support is used to treat cardiac arrest?
Chest compression and external ventillation
How does defibrillation work?
Electrical current delivered to heart
Depolarises all cells and puts them in the refractory period
Allows coordinated electrical activity to restart
Why is adrenaline used in cardiac arrest?
Enhances myocardial function and increases peripheral resistance
What is shock?
Acute condition of inadequate blood flow throughout body
What causes circulatory shock?
Catastrophic fall in arterial blood pressure due to a fall in CO or TPR
How is mean arterial BP calculated from cardiac output and TPR?
Mean arterial BP=COxTPR
In what ways can CO fall to cause shock?
Mechanical- pump can’t fill
Pump failure
Loss of blood volume