ECG (EKG)

Question 1

pathways that the AP follows in the atria

Answer 1

Bachmann’s bundle and inter-nodal pathways p. 277

Question 2

conduction velocity through the AV node is…

Answer 2

slower, allowing a delay between atrial and ventricular contractions p. 277

Question 3

normal ECG speed and deflection

Answer 3

25mm/sec and 10mm = 1mV p. 279

Question 4

rates of normal and latent pacemakers

Answer 4

SA node 60-80 bpm
AV node 40 bpm
ventricular muscle 30 bpm
p.282

Question 5

reentry conduction

Answer 5

an abnormal circuit in the heart; must have a barrier, a unidirectional block and conduction time has to exceed the effective refractory period p283-4

Question 6

fibrillation

Answer 6

random chaotic wavefronts move through the atria or ventricles causing there to be no effective pumping action :”bag of worms”

Question 7

heart failure

Answer 7

symptom complex (syndrome) that is normally secondary to cardiac (myocardial) failure; def: the heart is unable to meet the metabolic requirements of the peripheral tissues p.286

Question 8

heart failure stats

Answer 8

1-2% of general population; over 65 6-10%; #1 discharge diagnosis of Medicare; $20-40B spent annually p.286

Question 9

2 types of heart failure

Answer 9

systolic dysfunction and diastolic dysfunction; systolic dysfunction is when the heart cannot pump enough out via the ventricles; diastolic dysfunction causes there to be abnormal relaxation of the ventricles, ‘stiff ventricle’ p. 287

Question 10

4 stages of heart failure

Answer 10

Three categories to meet: risk factors, structural disease and symptoms. Four risk factors are A, B, C, and D. A is least, only risk factors. D is worst with all three categories met and the symptoms being severe. p.287

Question 11

how to measure preload

Answer 11

catheter in the LV, or wedge pressure (cath in the pulmonary artery); wedge pressure only works in the absence of mitral stenosis p. 287

Question 12

preload determines

Answer 12

the force of cardiac contraction (in a healthy heart)

Question 13

afterload is measured by…

Answer 13

SVR or aortic pressure

Question 14

contractility units

Answer 14

change in pressure over change in time (mmHg/sec) p.288

Question 15

heart failure can arise because of…

Answer 15

low preload (hypovolumic, constrictive pericarditis, tricuspid stenosis)
high afterload (aortic stenosis, hypertension)
impaired contractility (prior infarction, familial cardiomyopathy, infiltrative disease)
Low HR (bradyarrhythmia)
p.288

Question 16

heart failure (circulatory failure)

Answer 16

circulatory failure in the presence of a functioning heart secondary to hypothyroidism, beriberi, arteriovenous shunt, anemia p. 288

Question 17

treatments for heart failure

Answer 17

increase preload, increase contractility, decrease afterload

Question 18

abnormal Ca metabolism leads to

Answer 18

genetic reprogramming of the myocyte

Question 19

neurohumoral activation including

Answer 19

sympathetic innervation; renin-angiotensin-aldosterone system to raise Na retention and cause peripheral vasoconstriction p.290

Question 20

Kidney’s retain Na; effects?

Answer 20

raises the fluid levels in the body to the point that there is congestion in the lungs, edema, ascites, hepatomegaly (increases preload) p. 290

Question 21

renin-angiotensin system and sympathetic system kick in during CHF: effects?

Answer 21

raises afterload, which only exacerbates the problem by increasing the demand for O2 by raising contraction rate

Question 22

CHF causes HR to rise: effects?

Answer 22

increased demand for O2, with a 1:1 correlation in the rate of BPM to O2 demand p.290

Question 23

treatment for CHF involves…

Answer 23

knocking out the body’s own compensatory mechanisms: kidney Na retention: diuretics, renin-angiotensin/sympathetics - vasodilators: heart rate increases… not sure on this one…

Question 24

higher LVEDP pressures lead to…

Answer 24

pulmonary edema, when the filling pressure exceeds the oncotic pressure in the capillaries p. 290

Question 25

LVH (hypertrophy)

Answer 25

leads to CHF, and ventricular arrhythmia

Question 26

Clinical signs of CHF

Answer 26

fluid retention: Right side: edema, JVP, ascites, hepatomegaly
Left side congestion: rales, orthopnea, paroxysmal nocturnal dyspnea (PND) - 3 pillow people, dyspnea on exertion (DOE)
Low output: fatigue, disorientation, exercise intolerance, azotemia (nitrogen rich blood)