Physiology Flashcards by Naser Zalloum

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:

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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

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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%

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List 3 acute coronary sydromes

Unstable Angina
Acute myocardial infarction
sudden ischemic death
coronary artery dissection

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Name 3 physiologic components which contribute to coronary vascular resistance in the non-diseased heart

Viscous resistance
autoregulatory resistance
compressive resistance

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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

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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

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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.

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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)

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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``

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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

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What is normal Coronary blood flow

8 -15 ml/100/min in a beating heart

1.5 ml/100gm/min in an arresting heart

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List Endothelial vasodilators

Nitric Oxide
Endothelium Derived relaxing factor
Bradykinin
Prostayclin

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List Endothelial vasoconstrictors

Angiotensin II
Thromboxane
Edothelin-1 (ET1)

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What is normal range for mixed venous saturation

65-75%

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What are reasons why the mixed venous saturation would be less than 60%

Reduced oxygen-carrying capacity 
Acidosis 
Cardiac decompensation 
cellular injury
stress (? )

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What are reasons why the mixed venous saturation would be very high

sepsis
hypothermic
wedged PA catheter
physiologic or anatomic shunting

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List mechanisms of contractile dysfunction after myocardial stunning

generation of oxygen-derived free radicals
Calcium overload
Excitation-contraction uncoupling due to sarcoplasmic reticulum dysfunction
Insufficient energy production by mitochondria
Impaired energy use by myofibrils
Impaired sympathetic neural responsiveness
Damage to the extracellular collagen matrix
Decreased sensitivity of myofilaments to calcium

List mechanisms of ischemic reperfusion injury

Mitochondrial dysfunction
Calcium overload and cellular hypertracture
Oxygen and other free radical generation
Apoptosis
Intracellular calcium influx
Activation of leukocytes
Complement activation

List severe oxygen or free radicals that are generated with ischemia

superoxide anion
hydrogen peroxide
nitric oxide derived peroxynitrate
hydoxyl radical

How do neutrophils get activated during CPB

Activated by Kallikrein
contact system
complement system
Recruited by cytokines, complement, IL-1
Release cytokines, and phagocytose cells
Produce arachadonic acid metabolites and prostaglandins to mediate systemic inflammatory response syndrome

List fluid analysis of chlothorax

Odorless, milky white fluid
High triglyceride content 1.1 mmol/L 
Specific gravity > 1.012 
white count is lymphocytic 3000 to 20 000 cells/cc
Albumin 1-g/dl

List the factors in Child-pugh classification of assessing liver cirrhosis

Bilirubin 
Albumin 
INR 
encepalopathy 
ascities 
<7 cardiac surgery mortality is not affected
7-9 cardiac mortality is 41 to 80%
> 9  (1-3 month survival, cardiac surgery mortality is 100%)

How do you calculate shunt fraction for ASD

Qp/Qs

Sat (aortic) - Mixed venous sat (usually mix of IVC (2/3) and svc 1/3) DIVIDED by pulmonary venous sat - pulmonary artery sat

How do you calculate Pulmonary Vascular resistance (mmHg/L/min)

Mean pulmonary arterial pressure - pulmonary capillary wedge pressure/Cardiac outpult to get Dynes.sec.cm-5 you just multiple by 80

What are PVR limitations for operating when it comes to ASD

If PVR above 8 you do not operate If PVR is 6 to 8 check for vasodilatory challenge if the PVR is less then 6 then it's ok to operate

List advantages of LMWH

``` decreased heparin resistance decreased incidence of HIT (1 vs 5%) No need for monitoring Increased half life decreased risk of bleeding ```

How do you calculate mean pulmonary artery pressure

PASP -PADP/3 + PADP this is the same as mean arterial pressure

Describe the phases of Cardiomyocyte action potential

Phase 0: influx of sodium ions causes membrane to become transiently positive Phase 1: opening of the K challens to leave the cell (slowing makes it negative) Phase 2: Opening of Ca allows the balance of exit of K cells to keep a plateu phase. Phase 3: Closure of Ca channel (repolarization and -90m( Phase 4: resting period occurs because as cell prepares for next excitation

What is Bohr effect

Factors such as acidosis, hypercapnia, increasing temp that cause a right shift of the oxygen dissociation curve, thereby encouraging oxygen release to the tissues

What are the wave forms of the Central line tracing

A wave = atrial contraction x decent = atrial diastole c wave = ventricular systole leading to AV closure X prime decent = the remainder of x decent v wave = atrial filling against a closed AV valve, ventricular systole Y descent = ventricular diastole and opening of the AV valve

What happens in Cardiac tamponade

the waveform shows attenuated y descent (reduced atrial filling) with or without a prominent x descent

What happens to central line tracing in tricuspid regurgitation

Waveform shows large V waves

What happens to central line tracing with pacemaker syndrome

cannon a waves, due to atrial contraction against a closed tricuspid valve

What is the mechanism of action and the role of spinal cord stimulation in the treatment of angina

Simulate at level of T1-T2 Mechanism - suppressing the capacity of intrinsic cardiac neurons to generate activity during myocardial ischemia -reduces sympathetic activity by redistributing myocardial blood from nonishemic areas

List potential benefits of Pulsatile flow

Increase lymph flow, energy to microcirculation, oxygen consumption, cellular metabolism, tissue perfusion Decrease: vasoconstrive effect, acidosis, neuroendo response, critical capillary closing pressure

What are lesions of Atherosclerosis

Fatty streak---Invasion of intima Diffuse Intimal thickening--increased smooth muscle cells; increase connective tissue Fibrous plaque--proliferation smooth muscle cells, fibrous cap, zone of necrotic tissue Advanced lesion--calcification, hemorrhage, fissure and cracks in intima

What are the potential negative effects of Sodium Bicarbonate administration during CPB

Hypernatremia HYperosmolarity Shifting of oxyhemoglobin curve to the left (ihibiting release of oxygen) paradoxical acidosis from CO2 formation

Name 3 physiologic components which contribute to coronary resistance in the non-diseased heart

Auroregulatory resistance Compressive resistance viscous resistance

4 factors that results in a shift to the right of oxygen/hemoglobin dissociation curve

increase temp increased PCO2 decrease in pH increase in 2, 3 DPG

When an inotrope is administered, in which direction does the ESPVR slope shift

upward, leftward, rises more rapidly

IN the heart with systolic failure, in which direction does the ESPVR slope shift

downward, rightward, diminished rate of rise

List 4 physiologic changes associated with pregnancy that can complicate pre-existing cardiac disease

increase in cardiac output increase in circulating blood volume inferior vena caval compression from a gravid uterus with abrupt decrease in cardiac preload increase in circulating elastase which may weaken the aortic media hypercoagulable state with decrease protein S stasis and venous HTN