Physiology Flashcards
Define the following Stunned Hibernating re-reflow stone heart syndrome: massive muscular contraction of the whole myocardium that follows an end0stage massive reperfusion injury, no possible recuperation, very poor prognosis
Stunned: temporary akinesia of a myocardial territory after ischemia-reperfusion, reversible condition, excellent recovery
hibernating: akinetic territory that has the ability to recover contractile activity after angioplastic or surgical revascularization
no-reflow phenomenon: massive endovascular occlusion by neutrophil and platelet adhesion that follow a severe ischemia-reperfusion syndrome. poor recuperation and prognosis
stone heart syndrome:
What are potential negative effects of sodium bicarbonate administration during CPR
Hypernatremia
Hyperosmolarity
shifting oxyhemoglobin to the left (inhibiting the release of oxygen)
paradoxical acidosis from carbon dioxide formation
How much narrowing of the cross sectional area of a coronary must occur for there to be a reduction on coronary flow with exertion? at rest?
70% and 90%
List 3 acute coronary sydromes
Unstable Angina
Acute myocardial infarction
sudden ischemic death
coronary artery dissection
Name 3 physiologic components which contribute to coronary vascular resistance in the non-diseased heart
Viscous resistance
autoregulatory resistance
compressive resistance
List 4 factors that results in a shift to the right of the oxygen/hemoglobin dissociatiion curve
increased PCO2
increase in temperature
decrease in pH
increase in 2, 3 DPG
List the three basic categories of physiologicl derangements which can lead to tissue hypoxia and give one clinical example of each
Inadequate blood oxygenation cardiogenic/pulmonary edema ARDS acute lung injury inadequate delivery of oxygen to tissues low cardiac output Abnormal inability to extract from the blood sepsis
Pressure-volume loops and the End systolic pressure-volume relation slope is an indication of contractility
When an inotrope is administered, in which direction does the EPVR slope shift?
In heart with systolic failure in which direction does the ESPVR slope shift
Inotrope: upward and to the left
In failing heart– right and slightly down.
What is the equation for Laplace Law governing the wall stress of an arterial wall
Wall stress is proportional to (P x r) divided by (2 x wall thickness)
List 4 mechanisms responsible for the cellular damage produced during post-ischemic reperfusion injury
Release of free radical ( OH, O2, H2O2)
alteration of membrane phospholipid causing impairment of cellular tntegrity
Calcium-induced injury related to to increased Ca influsion
ATPase causing destruction of ATP intracellular storage
Leucocyte mediated injury
endothelial cell injury and no-reflow phenomenon``
What are determinants of oxygen delivery
cardiac output
hemoglobin
saturation of hemoglobin with oxygen saturation
dissolved oxygen measured by the partial pressure of oxygen
D = CO X 10 (HGB x 1.36 x O2sat) + PaO2 X 0.003
What is normal Coronary blood flow
8 -15 ml/100/min in a beating heart
1.5 ml/100gm/min in an arresting heart
List Endothelial vasodilators
Nitric Oxide
Endothelium Derived relaxing factor
Bradykinin
Prostayclin
List Endothelial vasoconstrictors
Angiotensin II
Thromboxane
Edothelin-1 (ET1)
What is normal range for mixed venous saturation
65-75%
What are reasons why the mixed venous saturation would be less than 60%
Reduced oxygen-carrying capacity Acidosis Cardiac decompensation cellular injury stress (? )
What are reasons why the mixed venous saturation would be very high
sepsis
hypothermic
wedged PA catheter
physiologic or anatomic shunting