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Cardiology_1 Flashcards

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1
Q

Truncus arteriosus gives rise to what?

A

ascending aorta and pulmonary trunk

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2
Q

bulbus cordis gives rise to what?

A

smooth parts (outflow tract) of left and right ventricles

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3
Q

primitive ventricle gives rise to what?

A

trabeculated left and right ventricles

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4
Q

primitive atria give rise to what?

A

trabeculated left and right atria

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5
Q

left horn of sinus venosus gives rise to what?

A

coronary sinus

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6
Q

right horn of SV gives rise to what?

A

smooth part of right atrium

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7
Q

right common cardinal vein and right anterior cardinal vein give rise to what?

A

SVC

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8
Q

what happens in the normal development of the truncus arteriosus?

A

neural crest migration → truncal and bulbar ridges that spiral and fuse to form the aorticopulmonary (AP) septum→ ascending aorta and pulmonary trunk

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9
Q

what are the truncus arteriosus pathologies?

A
  1. TGA • 2. ToF • 3. TA
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10
Q

what is the defect in transposition of the great vessels?

A

failure to spiral

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11
Q

what is the TA defect in tetralogy of Fallot?

A

skewed AP septum development

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12
Q

what is the defect in persistent TA?

A

partial AP septum development

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13
Q

3 steps in embryologic formation of interventricular septum?

A
  1. muscular ventricular septum forms- opening= interventricular foramen • 2. AP septum rotates and fuses with muscular ventricular septum to form membranous interventricular septum, closing interventricular foramen • 3. Growth of endocardial cushions separates atria from ventricles and contributes to both atrial separation and membranous portion of the interventricular septum
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14
Q

improper neural crest migration into the TA can result in what?

A

transposition of the great arteries or a persistent TA

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15
Q

in interventricular septum development, membranous septal defect causes what?

A

an initial left to right shunt, which later reverses to a right to left shunt due to onset of pulmonary hypertension (Eissenmenger’s syndrome)

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16
Q

8 steps in interatrial septum development?

A
  1. foramen primum narrows as septum primum grows toward endocardial cushions • 2. perforations in septum primum form foramen secundum (foramen primum disappears • 3. foramen scundum maintains right to left shunt as septum secundum begins to grow • 4. septum secundum contains a permanent opening (foramen ovale) • 5. foramen secundum enlarges and upper part of septum primum degenerates • 6. remaining portion of septum primum forms the valve of the foramen ovale • 7. septum secundum and septum primum fuse to form the atrial septum • 8. foramen ovale usually closes soon after birth because of ↑ LA pressure
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17
Q

what happens in pathology of interatrial septal development?

A

patent foramen ovale, caused by failure of the septum primum and septum secundum to fuse after birth

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18
Q

when is there fetal erythropoiesis in the yolk sac?

A

3-10wk

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19
Q

when is there fetal erythropoiesis in the liver?

A

6wk-birth

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20
Q

when is there fetal erythropoiesis in the spleen?

A

15-30wk

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21
Q

when is there fetal erythropoiesis in the bone marrow?

A

22wk-adult

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22
Q

mnemonic for fetal erythropoiesis?

A

young liver synthesizes blood

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23
Q

structure of HbF?

A

α2γ2

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24
Q

structure of HbA?

A

α2β2

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25
O2 content of fetal blood in the umbilical vein?
PO2~30 • 80% saturated with O2
26
O2 sat of umbilican arteries?
low
27
sites of 3 important shunts of fetal circulation?
1. ductus venosus • 2. foramen ovale • 3. ductus arteriosus
28
action of shunt at ductus venosus in fetal circulation?
blood entering the fetus through the umbilical vein is coducted via the ductus venosus into the IVC to bypass the hepatic circulation
29
action of the shunt at the foramen ovale in fetal circulation?
most oxygenated blood reaching the heart via the IVC is diverted through the foramen ovale and pumped out the aorta to the head and body
30
action of the shunt at the ductus arteriosus in fetal circulation?
deoxygenated blood entering the RA from the SVC enters the RV, is expelled into the pulmonary artery, then passes through the ductus arteriosus into the descending aorta
31
what happens to fetal circulation at birth when the infant takes a breath?
↓ resistance in pulmonary vasculature causes ↑ LA pressure vs RA pressure→ • foramen ovale closes (now called fossa ovalis) → • ↑ in O2 leads to ↓ in prostaglandins, causing closure of ductus arteriosus
32
what helps close PDA?
indomethacin
33
what keeps PDA open?
PGE1, PGE2
34
post natal derivative of the umbilical vein?
ligamentum teres hepatis, contained in falciform ligament
35
postnatal derivatives of umbilical arteries?
medial umbilical ligaments
36
postnatal derivatives of ductus arteriosus?
ligamentum arteriosum
37
postnatal derivative of ductus venosus?
ligamentum venosum
38
postnatal derivative of foramen ovale?
fossa ovalis
39
postnatal derivative of allantois?
urachus-median umbilical ligament
40
what is the urachus part of?
the allantoic duct between the bladder and the umbilicus
41
what finding is a remnant of the urachus?
urachal cyst, or sinus
42
postnatal derivative of the notochord?
nucleus pulplosus of intervertebral disc
43
LCX supplies what?
lateral and posterior walls of left ventricle
44
LAD supplies what?
anterior 2/3 of interventricular septum, anterior papillary muscle, and anterior surface of left ventricle
45
PD supplies what?
posterior 1/3 of interventricular septum and posterior walls of ventricles
46
acute marignal artery supplies what?
right ventricle
47
SA and AV nodes are usually supplied by what?
RCA
48
frequency and features of right dominant coronary circulation?
85% • PD arises from RCA
49
frequency and features of left-dominant coronary circulation?
8% • PD arises from LCX
50
frequency and features of codominant circulation?
7% • PD arises from both LCX and RCA
51
coronary artery occlusion most commonly occurs where?
in LAD
52
when do coronary arteries fill?
during diastole
53
most posterior part of the heart is what?
LA
54
enlargement of LA can cause what?
dysphagia (due to compression of the esophagus) or hoarseness (due to compression of the left recurrent laryngeal nerve)
55
transesophageal echocardiography is useful for diagnosing what?
LA enlargement • aortic dissection • thoracic aortic aneurysm
56
equations for cardiac output?
CO= SV x HR • • Fick's: • CO= (rate of O2 consumption)/((arterial O2 content)- (venous O2 content))
57
equation for MAP?
MAP= CO x TPR • • MAP= 2/3 diastolic pressure + 1/3 systolic
58
pulse pressure=?
systolic pressure - diastolic pressure
59
pulse pressure is proportional to what?
stroke volume
60
equations for stroke volume?
SV = CO/HR = EDV - ESV
61
during the early stages of exercise CO is maintained by what?
↑ HR and ↑ SV
62
during the late stages of exercise, CO is maintained by what?
↑ HR only (SV plateaus)
63
what happens during exercise if HR is too high?
diastolic filling is incomplete and CO ↓
64
cardiac variables that affect stroke volume?
SV CAP • Stroke Volume affected by Contractility, Afterload, and Preload
65
↑ SV when what?
↑ preload, ↓ afterload, ↑ contractility
66
contractility (and SV) ↑ with what?
1. catecholamines • 2. ↑ intracellular Ca++ • 3. ↓ extracellular Na+ • 4. Digitalis
67
how do catecholamines ↑ contractility?
↑ activity of Ca++ pump in sarcoplasmic reticulum
68
how does a ↓ in extracellular Na+ ↑ contractility?
↓ activity of Na+/Ca++ exchanger
69
how does digitalis ↑ contractility?
blocks Na+/K+ pump → ↑ intracellular Na+ →↓ Na+/Ca++ exchanger activity → ↑ intracellular Ca++
70
contractility and SV ↓ with what?
1. β blockade • 2. heart failure (systolic dysfunction) • 3. acidosis • 4. hypoxia/hypercapnia (↓PO2/↑PCO2) • 5. Non-dihydropyridine Ca++ channel blockers
71
effect of anxiety, exercise, and pregnancy on SV?
↑
72
myocardial O2 demand is ↑ by what?
↑ afterload (proportional to arterial pressure) • ↑ contractility • ↑ heart rate • ↑ heart size (↑wall tension)
73
preload = ?
ventricular EDV
74
afterload=?
MAP (proportional to peripheral resistance)
75
agents that ↓ preload?
vEnodilators (nitroglycerin)
76
agents that ↓ afterload?
vAsodilators (hydrAlazine)
77
preload ↑ with what?
1. exercise (slightly) • 2. ↑ blood volume (overtransfusion) • 3. excitement (↑ sympathetic activity)
78
on Starling curve, force of contraction is proportional to what?
end-diastolic length of cardiac muscle fiber (preload)
79
on Starling curve, what are the factors that increase contractility?
sympathetic stimulation • catecholamines • digoxin
80
on starling curve, which factors ↓ contractility?
loss of myocardium (MI) • β blockers • Ca++ channel blockers
81
equation for EF?
EF= SV/EDV = (EDV-ESV)/EDV
82
EF is an index of what?
ventricular contractility
83
normal EF?
>=55%
84
EF ↓ in what?
systolic heart failure
85
ΔP =?
Q x R
86
equation for resistance?
resistance = (driving pressure ΔP)/(Flow Q)= (8ηl)/πr^4
87
equation for total resistance of vessels in series?
0
88
1/Toral Resistance of vessels in parallel?
= 1/R1 + 1/R2 + 1/R3...
89
viscosity ↑ in what?
1. polycythemia • 2. hyperproteinemic states (multiple myeloma) • 3. hereditary spherocytosis
90
viscosity ↓ in what?
anemia
91
pressure gradient drives blood flow where?
from high pressure to low pressure
92
resistance is proportional to what?
viscosity and vessel length
93
viscosity is inversely proportional to what?
the radius to the 4th power
94
what accounts for most of total peripheral resistance?
arterioles
95
what vessels regulate capillary flow?
arterioles
96
where is the operating point of the heart on the cardiac and vascular function curve?
intersection where cardiac output and venous return are equal
97
what causes the operating point of the heart on the cardiac and vascular function curve to shift straight down?
↑ TPR, hemorrhage before compensation can occur
98
what causes the operating point of the heart on the cardiac an vascular function curve to shift straight up?
↓ TPR, exercise, AV shunt
99
what causes the operating point of the heart to shift downward and rightward along the venous return curve on the cardiac and vascular function curve?
heart failure • narcotic overdose
100
what causes an upward shift in the CO curve?
#NAME?
101
what causes a downward shift in the CO curve?
#NAME?
102
what causes a rightward shift in the venous return curve?
↑ blood volume
103
what causes a leftward shift in the venous return curve?
↓ blood volume
104
what is the X intercept of the venous return curve?
mean systemic filling pressure
105
what are the 5 phases of the left ventricle in the cardiac cycle?
1. isovolumetric contraction • 2. systolic ejection • 3. isovolumetric relaxation • 4. rapid filling • 5. reduced filling
106
what is isovolumetric contraction?
period between mitral valve closure and aortic valve opening
107
what is the period of highest O2 consumption during the cardiac cycle?
isovolumetric contraction
108
what is systolic ejection?
period between aortic valve opening and closing
109
what is isovolumetric relaxation?
period between aortic valve closing and mitral valve opening
110
what is rapid filling?
period just after mitral valve opening
111
what is reduced filling?
period just before mitral valve closure
112
what causes a rightward EDV expansion without an upward pressure expansion in the LV cardiac cycle P/V curve?
↑preload → ↑SV
113
what causes a leftward ESV expansion with an upward pressure expansion on a LV cardiac cycle P/V curve?
↑ contractility • ↑ SV • ↑ EF • ↓ ESV
114
what causes a leftward ESV contraction with an upward pressure expansion on a LV cardiac cycle P/V curve?
↑ afterload • ↑ aortic pressure • ↓ SV • ↑ ESV
115
what causes S1 sound?
mitral and tricuspid valve closure
116
S1 is loudest where?
at mitral area
117
what causes S2 sound?
aortic and pulmonary valve closure
118
where is S2 loudest?
at left sternal border
119
when is S3 heard?
in early diastole during rapid ventricular filling phase
120
S3 is associated with what?
↑ filling pressures (MR, CHF)
121
S3 is more common in which types of ventricles?
dilated ventricles, but normal in children and pregnant women
122
when do you hear S4?
atrial kick in late diastole
123
what causes S4?
high atrial pressure • LA must push against stiff LV wall
124
S4 associated with what?
ventricular hypertrophy
125
what does JVP a wave correspond to?
atrial contraction
126
what does the JVP c wave correspond to?
RV contraction (closed tricuspid valve bulging into atrium)
127
what does the JVP x descent correspond to?
atrial relaxation and downward displacement of closed tricuspid valve during ventricular contraction
128
what does the JVP v wave correspond to?
↑ right atrial pressure due to filling against closed tricuspid valve
129
what does the JVP y descent correspond to?
blood flow from RA to RV
130
what happens in normal splitting?
inspiration → • drop in intrathoracic pressure → • ↑ venous return to the RV → • ↑ RV stroke volume → • ↑ RV ejection time → • delayed closure of the pulmonic valve
131
what else contributes to the delayed closure of the pulmonic valve in normal splitting?
↓ pulmonary impedance ( ↑ capacity of the pulmonary circulation)
132
what does normal splitting sound like?
A2 and P2 are close during expiration, • A2 and P2 are only slightly more separated during inspiration
133
wide splitting is seen in which conditions?
those that delay RV emptying (pulmonic stenosis, RBB block)
134
what happens in wide splitting?
delay in RV emptying causes delayed pulmonic sound (regardless of breath)
135
what does wide splitting sound like?
an exaggeration of normal splitting • Ex: A2 and P2 are split as wide as normal inspiration • Ins: A2 and P2 are split much wider than normal
136
fixed splitting is seen in what?
ASD
137
what happens in fixed splitting?
ASD → left to right shunt → ↑ RA and RV volumes → ↑ flow through pulmonic valve such that, regardless of breath, pulmonic closure is greatly delayed
138
paradoxical splitting is seen in what?
conditions that delay LV emptying (aortic stenosis, LBB block)
139
what happens in paradoxical splitting?
normal order of valve closure is reversed so that P2 sound occurs before A2.
140
what does paradoxical splitting sound like?
on inspiration, P2 closes later and moves closer to A2, thereby 'paradoxically' eliminating the split
141
what can cause a systolic murmur in the aortic area?
aortic stenosis • flow murmur • aortic valve sclerosis
142
where is the aortic auscultation area?
2nd intercostal space RSB
143
what causes a systolic ejection murmur in the pulmonic area?
pulmonic stenosis • flow murmur (ASD, PDA)
144
where is the pulmonic area for ausculation?
2nd interspace LSB
145
what causes a pansystolic murmur at the tricuspid area?
tricuspid regurgitation • ventricular septal defect
146
what causes diastolic murmur at the tricuspid area?
tricuspid stenosis • ASD
147
where is the tricuspid area for auscultation?
5th interspace LSB
148
what causes a systolic murmur in the mitral area?
mitral regurgitation
149
what causes a diastolic murmur in the mitral area?
mitral stenosis
150
where is the mitral area for auscultation?
5th interspace mid clavicular line
151
what causes diastolic murmur at the left sternal border?
aortic regurgitation • pulmonic regurgitation
152
what causes systolic murmur at left sternal border?
hypertrophic cardiomyopathy
153
what are the auscultation findings in ASD?
pulmonary flow murmur • diastolic rumble (tricuspid) • blood flow across the ASD doesn't cause a murmur because there is no pressure gradient • murmur → louder diastolic murmur of pulmonic regurgitation from dilation of pulmonary artery
154
the continuous, machine-like murmur of PDA is best appreciated where?
left infraclavicular region
155
what is the effect of inspiration on ausculation?
↑ intensity of right heart sounds
156
what is the effect of expiration on auscultation?
↑ intensity of left heart sounds
157
what is the effect of hand grip maneuver on auscultation (↑ systemic vascular resistance)?
↑ intensity of MR, AR, VSD, MVP murmurs • ↓ intensity of AS, hypertrophic cardiomyopathy murmurs
158
what is the effect of the vasalva maneuver (↓ venous return) on auscultation?
↓ intensity of most murmurs • ↑ intensity of MVP, hypertrophic cardiomyopathy murmurs
159
what is the effect of rapid squatting (↑ venous return, ↑ preload, ↑afterload with prolonged squatting)?
↓ intensity of MVP, hypertrophic cardiomyopathy murmurs
160
conditions associated with systolic heart sounds include what?
aortic/pulmonic stenosis • mitral/tricuspid regurgitation • VSD
161
conditons associated with diastolic heart sounds include what?
aortic/pulmonic regurgitation • mitral/tricuspid stenosis
162
what does mitral/tricuspid regurgitation sound like?
holosystolic, high-pitched "blowing murmur"
163
mitral regurgitation is loudest where?
at apex and radiates to toward axilla
164
mitral regurgitation sound is enhanced by what?
maneuvers that ↑ TPR (squatting, hand grip) or LA return (expiration)
165
MR is often due to what?
ischemic heart disease, mitral valve prolapse, LV dilation
166
where is tricuspid regurgitation loudest?
loudest at tricuspid area and radiates to right sternal border
167
tricuspid regurgitation sound enhanced by what?
maneuvers that ↑ RA return (inspiration)
168
TR can be caused by what?
RV dilation
169
rheumatic fever and infective endocarditis can cause which heart sounds?
MR or TR
170
what does Aortic stenosis sound like?
crescendo-decrescendo systolic ejection murmur following ejection click • radiates to carotids/heart base
171
what causes ejection click in aortic stenosis?
EC due to abrupt halting of valve leaflets
172
pressure gradient in aortic stenosis?
LV>> aortic pressure during systole
173
pulse findings in aortic stenosis?
pulsus parvus et tardus' • pulses are weak with a delayed peak
174
aortic stenosis can lead to what?
Syncope, Angina, Dyspnea on exertion (SAD)
175
aortic stenosis is due to what?
age related calcific aortic stenosis or bicuspid aortic valve
176
what does VSD sound like?
holosystolic, harsh sounding murmur
177
where is VSD loudest?
tricuspid area
178
VSD sound can be accentuated how?
hand grip maneuver due to increased afterload
179
what does MVP sound like?
late systolic crescendo murmur with midsystolic click
180
what causes MC?
sudden tensing of the chordae tendineae
181
what is the most frequent valvular lesion?
MVP
182
MVP is best heard where?
over apex
183
when is MVP loudest?
S2
184
severity of MVP?
usually benign
185
MVP can predispose to what?
infective endocarditis
186
MVP can be caused by what?
myxomatous degeneration • rheumatic fever • chordae rupture
187
MVP enhanced by what?
maneuvers that ↓ Venous return (standing or vasalva)
188
what does aortic regurgitation sound like?
immediate high pitched "blowing" diastolic decrescendo murmur
189
pulses in AR?
wide pulse pressure when chronic; can present with bounding pulses and head bobbing
190
AR is often due to what?
aortic root dilation, bicuspid aortic valve, endocarditis, rheumatic fever
191
what ↑ murmur in AR?
hand grip
192
effect of vasodilators on AR?
↓ intensity of murmur
193
what does MS sound like?
follows opening snap • delayed rumbling late diastolic murmur
194
what causes OS in MS?
abrupt halt in leaflet motion in diastole, after rapid opening due to fusion at leaflet tips
195
pressure gradient in MS?
LA>>LV during diastole
196
MS often occurs secondary to what?
rheumatic fever
197
chronic MS can result in what?
LA dilation
198
MS sound is enhanced by what?
maneuvers that ↑ LA return (expiration)
199
what does PDA sound like?
continuous machine like murmur
200
when is PDA loudest?
S2
201
PDA is often due to what?
congenital rubella or prematurity
202
where is PDA best heard?
left infraclavicular area
203
ventricular action potential also occurs where?
in bundle of His and Purkinje fibers
204
what happens in Phase 0 of ventricular action potential?
rapid upstroke- voltage gated Na+ channels open
205
what happens in Phase 1 of ventricular action potential?
initial repolarization- inactivation of voltage gated Na+ channels. Voltage gated K+ channels begin to open
206
what happens in Phase 2 of ventricular action potential?
plateau-Ca++ influx through voltage gated Ca++ channels balances K+ efflux • Ca++ influx triggers Ca++ release from sarcoplasmic reticulum and myocyte contraction
207
what happens in phase 3 of ventricular action potential?
rapid repolarization= massive K+ efflux due to opening of voltage-gated slow K+ channels and closure of voltage gated Ca++ channels
208
what happens in phase 4 of the ventricular action potential?
resting potential- high K+ permeability through K+ channels
209
difference between cardiac muscle AP and skeletal muscle?
1. cardiac muscle AP has a plateau, which is due to Ca++ influx and K+ efflux, myocyte contraction occurs due to Ca++ induced Ca++ release from the sarcoplasmic reticulum • 2. cardiac nodal cells spontaneously depolarize during diastole resulting in automaticity due to If channels • 3. Cardiac myocytes are electrically coupled to eachother by gap junctions
210
what do If chanels do?
funny current channels responsible for a slow, mixed Na+/K+ inward current
211
what is the direction of the leak currents in cardiac ventricular myocytes?
K+ out • Na+, Ca++ in
212
pacemaker action potential occurs where?
in the SA and AV nodes
213
what happens in phase 0 of the pacemaker action potential?
upstroke- opening of VG Ca++ channels • fast VG Na channels are permanently inactivated because of the less negative resting voltage of these cells
214
permanent fast VG Na channel inactivation in the pacemaker cells results in what?
slow conduction velocity that is used by the AV node to prolong transmission from the atria to the ventricles
215
what happens in Phase 2 or pacemaker potential?
plateau is absent
216
what happens in phase 3 of the pacemaker potential?
inactivation of the Ca++ channels and ↑ activation of K+ channels→ ↑ K+ efflux
217
what happens in phase 4 of the pacemaker potential?
slow diastolic depolarization- membrane potential spontaneously depolarizes as Na+ conductance ↑ (If different from Ina in phase 0 of ventricular action potential)
218
phase 4 of the pacemaker potential accounts for what?
automaticity of SA and AV nodes
219
slope of phase 4 in the SA node determines what?
HR
220
effect of ACh/adenosine on SA node?
↓ the rate of diastolic depolarization and ↓ HR
221
effect of catecholamines on SA node?
↑ depolarization and ↑ heart rate
222
effect of sympathetic stimulation on SA/AV node?
↑ the chance that If channels are open and thus ↑ HR
223
P wave corresponds to what?
atrial depolarization
224
atrial repolarization in ECG?
masked by QRS complex
225
PR interval corresponds to what?
conduction delay through AV node
226
normal PR interval?
<200 ms
227
QRS complex correspondes to what?
ventricular depolarization
228
normal duration of QRS complex?
<120s
229
QT interval corresponds to what?
mechanical contraction of the ventricles
230
T wave corresponds to what?
ventricular repolarization
231
T wave inversion may indicate what?
recent MI
232
ST segment corresponds to what?
isoelectric, ventricles depolarized
233
U wave is caused by what?
hypokalemia • bradycardia
234
relative speed of conduction in the heart?
purkinje > atria > ventricles > AV nodes
235
relative speed of conduction in the pacemaker cells?
SA node> AV> Bundle of his/purkinje/ventricles
236
what is the conduction pathway in the heart?
SA node → atria → AV node → common bundle→ bundle branches→ purkinje fibers→ ventricles
237
dominant pacemaker in heart?
SA node pacemaker inherent dominance with slow phase of the upstroke
238
what is the delay in the AV node?
100ms delay- atrioventricular delay; allows time for ventricular filling
239
what happens in torsades de pointes?
ventricular tachycardia, characterized by shifting sinusoidal waveforms on ECG, can progress to ventricular fibrillation
240
what predisposes to torsades de pointes?
anything that prolongs the QT interval
241
treatment for torsades de pointes?
magnesium sulfate
242
congenital long QT syndromes are most often due to what?
defects in cardiac sodium or potassium channels
243
what condition has long QT syndrome that presents with severe sensorineural deafness?
Jervell and Lange-Nielsen syndrome
244
how does atrial fibrillation look?
chaotic and erratic baseline (irregularly irregular) with no discrete P waves in between irregularly spaced QRS complexes
245
atrial fibrillation can result in what?
atrial stasis and lead to stroke
246
tx for atrial fibrillation?
rate control • anticoagulation • possible cardioversion
247
what does atrial flutter look like?
a rapid succession of identical, back-to-back atrial depolarization waves • 'saw tooth' appearance
248
pharmacologic conversion to sinus rhythm in atrial flutter?
Class IA, IC, or III antiarrhythmics
249
rate control in atrial flutter?
β-blocker or calcium channel blocker
250
what does ventricular fibrillation look like?
a completely erratic rhythm with no identifiable waves
251
severity of ventricular fibrillation?
fatal arrhythmia without immediate CPR and defibrillation
252
features of 1st degree AV block?
prolonged PR interval >200ms • asymptomatic
253
features of 2nd degree AV block Mobitz type I (Wenckebach)?
progressive lenghtening of the PR interval until a beat is dropped • usually asymptomatic
254
features of Mobitz type II?
dropped beats that are not preceded by a change in the length of the PR interval
255
severity of Mobitz type II?
these abrupt, nonconducted p waves result in a pathologic condition
256
mobitz type II is often found as what?
2:1 block, where there are >=2 p waves to 1 QRS
257
mobitz type II often treated with what?
pacemaker
258
mobitz type II may progress to what?
3rd degree block
259
what happens in 3rd degree (complete) heart block?
the atria and ventricles beat independently of each other • both p waves and QRS complexes are present, though P waves bear no relation to the QRS complexes
260
which rate is faster in 3rd degree heart block?
atrial rate is faster than ventricular rate
261
3rd degree heart block is usually treated with what?
a pacemaker
262
which disease can result in 3rd degree heart block?
Lyme disease
263
ANP is released from where?
atrial myocytes
264
ANP is released in response to what?
↑ blood volume and pressure
265
ANP causes what?
generalized vascular relaxation and ↓ Na+ reabsorption at the medullary collecting tubule
266
effect of ANP on renal blood flow?
constricts efferent renal arterioles and dilates afferent arterioles (cGMP mediated), promoting diuresis and contributing to the escape from aldosterone mechanism
267
aortic arch baroreceptors transmit info where?
via vagus nerve to solitary nucleus of medulla (responds only to ↑ BP)
268
carotid sinus baroreceptor transmits info where?
via glossopharyngeal nerve to solitary nucleus of medulla (responds to ↑ and ↓ in BP)
269
what happens at baroreceptors in response to hypotension?
↓ arterial pressure → • ↓ stretch → • ↓ afferent baroreceptor firing→ • ↑ efferent sympathetic firing and ↓ efferent parasympathetic stimulation → • vasoconstriction, ↑ HR, ↑ contractility, ↑ BP
270
baroreceptors are important in the response to what?
severe hemorrhage
271
effect of carotid massage on baroreceptors?
↑ pressure on carotid artery → ↑ stretch → ↑ afferent baroreceptor firing → ↓ HR
272
baroreceptors contribute to which reaction?
Cushing reaction
273
what happens in Cushing reaction?
triad of hypertension, bradycardia, and respiratory depression
274
mechanism of Cushing reaction?
↑ ICP constricts arterioles→ cerebral ischemia and reflex sympathetic increase in perfusion pressure (hypertension)→ ↑ stretch → reflex baroreceptor induced-bradycardia
275
what happens in stimulation of peripheral chemoreceptors?
carotid and aortic bodies are stimulated by ↓ PO2 (<60mmHg), ↑ PCO2, and ↓ pH of blood
276
what happens in stimulation of central chemoreceptors?
are stimulated by changes in pH and PCO2 of brain interstitial fluid, which in turn are influenced by arterial CO2
277
central chemoreceptors do not directly respond to what?
PO2
278
what is the organ with the largest blood flow?
Lung (100% of CO)
279
what is the organ with the largest share of systemic cardiac output?
liver
280
which organ has the highest blood flow per gram of tissue?
kidney
281
which organ has the largest arteriovenous O2 difference?
heart
282
why does heart have the largest arteriovenous O2 difference?
becuase O2 extraction is 80%
283
how is O2 demand met in heart?
↑ O2 demand is met by ↑ coronary blood flow, not by ↑ extraction of O2
284
what is the normal pressure in the RA?
<5
285
what is the normal pressure in the RV?
25-May
286
what is the normal pressure in the PA?
25-Oct
287
what is the normal pressure in the LA?
<12
288
what is the normal pressure in the LV?
130/10
289
what is the normal pressure in the aorta?
130/90
290
PCWP is a good approximation of what?
left atrial pressure
291
when is PCWP> LV diastolic pressure?
mitral stenosis
292
how is PCWP measured?
Swan Ganz catheter
293
what is autoregulation?
how blood flow to an organ remains constant over a wide range of perfusion pressures
294
what are the factors determining autoregulation in the heart?
Local metabolites (vasodilatory)-CO2, adenosine, NO
295
what are the factors determining autoregulation in the brain?
Local metabolites (vasodilatory)-CO2 (pH)
296
what are the factors determining autoregulation in the kidneys?
myogenic and tubuloglomerular feedback
297
what are the factors determining autoregulation in the lungs?
hypoxia causes vasoconstriction
298
what are the factors determining autoregulation in skeletal muscle?
local metabolites- lactate, adenosine, K+
299
what are the factors determining autoregulation in the skin?
sympathetic stimulation most important mechanism-temperature control
300
what determines fluid movement through capillary membranes?
starling forces
301
what are the 4 starling forces?
Pc • Pi • πc • πi
302
what is Pc?
capillary pressure- pushes fluid out of capillary
303
what is Pi?
interstitial fluid capillary- pushes fluid into capillary
304
what is πc?
plasma colloid osmotic pressure- pulls fluid into capillary
305
what is πi?
interstitial fluid colloid osmotic pressure-pulls fluid out of capillary
306
equation for net filtration pressure?
Pnet= [(Pc - Pi) - (πc - πi)]
307
what is Kf?
filtration constant (capillary permeability)
308
what is Jv?
net fluid flow= Kf x Pnet
309
what is edema?
excess fluid outflow into interstitium
310
edema is commonly caused by what?
↑ capillary pressure (heart failure) • ↓ plasma proteins (nephrotic syndrome, liver failure) • ↑ capillary permeability (toxins, infections, burns) • ↑ interstitial colloid osmotic pressure (lymphatic blockage)
311
what is the most common cause of early cyanosis?
Tetralogy of Fallot
312
which congenital heart diseases make up the right to left shunts (early cyanosis)-blue babies?
5T's • Tetralogy of Fallot • Transposition of the great vessels • persistent Truncus arteriosus • Tricuspid atresia • Total anomalous pulmonary venous return
313
features of Persistent Truncus Arteriosus?
failure of truncus arteriosus to divide into pulmonary trunk and aorta
314
most patients with persistent truncus arteriosus have what?
accompanying VSD
315
tricuspid atresia is characterized by what?
absence of tricuspid valve and hypoplastic RV
316
tricuspid atresia requires what for viability?
both ASD and VSD
317
what happens in TAPVR?
pulmonary veins drain into right heart circulation (SVC, coronary sinus, etc)
318
TAPVR is associated with what?
ASD and sometimes PDA to allow for right to left shunting to maintain CO
319
which congenital heart abnormalities make up the left to right shunts (late cyanosis)-blue kids?
VSD • ASD • PDA
320
what is the most common congenital cardiac anomaly?
VSD
321
findings in ASD?
loud S1, wide, fixed split S2
322
what do you use to close PDA?
indomethacin
323
what is the frequency of the congenital left to right shunts?
VSD > ASD > PDA
324
what happens in Eisenmenger's syndrome?
uncorrected VSD, ASD, or PDA causes compensatory pulmonary vascular hypertrophy, which results in progressive pulmonary hypertension
325
what happens in Eisenmenger's syndrome as pulmonary resistance increases?
the shunt reverses from left to right to right to left, which causes late cyanosis, clubbing, and polycythemia
326
tetralogy of fallot is caused by what?
anterosuperior displacement of the infundibular septum
327
what is the mnemonic for the components of ToF?
PROVe • 1. Pulmonary infundibular stenosis • 2. RVH • 3. Overriding aorta (overrides the VSD) • 4. VSD
328
what is the most important determinant for prognosis in ToF?
pulmonary infundibular stenosis
329
in ToF early cyanosis (tet spells) caused by what?
a right to left shunt across the VSD
330
difference between isolated VSD and VSD in ToF?
isolated VSDs usually flow left to right (acyanotic) • in tetralogy, pulmonary stenosis forces right to left (cyanotic) flow and causes RVH
331
how does RVH in ToF look?
boot shaped heart on CXR
332
patients with ToF learn what compensatory mechanism?
squat to relieve cyanotic symptoms
333
why do patients with ToF squat?
reduces blood flow to the legs, ↑ PVR, and thus ↓ the cyanotic right to left shunt across the VSD
334
what is the preferred treatment for ToF?
early, primary surgical correction
335
what happens in transposition of great vessels?
aorta leaves RV (anterior) and pulmonary trunk leaves LV (posterior)→ separation of systemic and pulmonary circulations
336
transposition of the great vessels not compatible with life unless what?
a shunt is present to allow adequate mixing of blood (VSD, PDA, or patent foramen ovale)
337
transposition of great vessels is due to what?
failure of aorticopulmonary septum to spiral
338
prognosis of transposition of great vessels?
without surgical correction, most infants die within the first few months of life
339
coarctation of the aorta can result in what?
AR
340
what is infantile type of coarctation of the aorta?
aortic stenosis proximal to insertion of ductus arteriosus (preductal)
341
preductal coarctation of the aorta is associated with what?
Turner syndrome
342
what needs to be checked in infantile coarctation of the aorta?
check femoral pulses on physical exam
343
what is adult type coarctation of the aorta?
stenosis is distal to ligamentum arteriosum (postductal)
344
postductal coarctation of the aorta is associated with what?
notching of the ribs (due to collateral circulation), hypertension in upper extremities, weak pulses in lower extremities
345
postductal coarctation of the aorta is most commonly associated with what?
bicuspid aortic valve
346
what is going on in patent ductus arteriosus in the fetal period?
shunt is right to left (normal)
347
what happens to patent ductus arteriosus in the neonatal period?
lung resistance ↓ and shunt becomes left to right with subsequent RVH and/or LVH and failure (abnormal)
348
patent ductus arteriosus is associated with what finding?
continuous machine like murmur
349
in PDA, patency is maintained with what?
PGE synthesis and low O2 tension
350
uncorrected PDA can eventually result in what?
late cyanosis in the lower extremities (differential cyanosis)
351
when is PDA normal?
PDA is normal in utero and only closes after birth
► Med Notes
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