Cardiac Physiology Flashcards
1
Q
What is the primary determinant of myocardial oxygen consumption?
A
Heart rate
2
Q
How much oxygen does the heart extract?
A
75-80%
3
Q
What valve corresponds with the beginning of the R wave?
A
Closing of the mitral valve
4
Q
What corresponds with the end of the QRS?
A
Opening of the aortic valve
5
Q
What corresponds with the end of the T wave?
A
Closure of the aortic valve
6
Q
What does mild aortic stenosis also suggest?
A
Diastolic dysfunction
7
Q
What cardiac output dependent on in someone with diastolic dysfunction?
A
LV filling during diastole
8
Q
What does LV filling depend on?
A
Proper atrial ejection (only happens in normal sinus rhythm)
Enough time to fill (HR control)
9
Q
Assuming normal cardiac function, what is the relationship of partial pressures of inhaled anesthetics at equilibrium in the CNS, blood and alveoli?
A
Pcns=Pblood = Palveoli
10
Q
What are the sympathetic cardiac innervations?
A
Alpha 1
Beta 1
Beta 2
11
Q
What do the sympathetic fibers travel through?
A
The stellate ganglions
12
Q
Which side has a greater effect on heart rate?
A
The right stellate
13
Q
Which. Stellate ganglia has more effect on MAP and contractility
A
Left
14
Q
What does beta 2 do in the heart?
A
Positive chronotropy > inotropy
15
Q
What does alpha 1 do in the heart?
A
Positive inotropy
16
Q
What are the sympathetic cardiac innervations?
A
Alpha 1
Beta 1
Beta 2
17
Q
What do the sympathetic fibers travel through?
A
The stellate ganglions
18
Q
Which side has a greater effect on heart rate?
A
The right stellate
19
Q
Which. Stellate ganglia has more effect on MAP and contractility
A
Left
20
Q
What does beta 2 do in the heart?
A
Positive chronotropy > inotropy
21
Q
What does alpha 1 do in the heart?
A
Positive inotropy
22
Q
What is phase 0 of the ventricular contraction?
A
Fast sodium influx
23
Q
What is phase 1?
A
Inactivation of sodium channels
Transient leak of potassium out (partial repolarization)
24
Q
What is phase 2?
A
The plateau where L type calcium channels open to release calcium from the sarcoplasmic reticulum
25
What is phase 3?
Complete repolarization by efflux of potassium by voltage gated K channel and calcium activated channels.
26
What is phase 4?
The resting phase maintained by K
27
What happens to the heart in hypocalcemia?
Less calcium is available for release so you get a slower repolarization time (wider QRS and prolonged QT)
28
What is the second messenger in cardiac myocytes?
IP3 which stimulates the release of cytoplasmic calcium which in turn activates the ryanodine receptors on the sarcoplasmic reticulum
29
What is the second messenger in cardiac myocytes?
IP3 which stimulates the release of cytoplasmic calcium which in turn activates the ryanodine receptors on the sarcoplasmic reticulum
30
What do T wave inversions in the precordial leads indicate?
Severe right heart dysfunction (PE)
31
Where do thebesian veins empty?
Into the left heart
32
What are the most common cardiac benign tumors in adults and where are they found?
Myxoma
| Found in the left atrium and inter atrial septum
33
Where does RCC Mets usually end up in the heart?
Right atrium and IVC
34
What is normal PCWP?
6-12 mm Hg
35
What is a normal CI?
2.5-4L/min/m2
36
What is normal SVR?
800-1200 dynes X sec/cm 5
37
What is resynchronization therapy
Biventricular packng where the pacer wires are in the right atrium, right ventricle and coronary sinus (activates the left ventricle)
38
What does unipolar pacemaking require?
Farther distance for current to travel so a large stimulus artifact can be seen on ECG
39
What may happen with unipolar pacemakers?
Other excitable tissue may be stimulated due to the large current required
40
What is pulses paradoxus?
A decrease greater than 10 mmHg in systemic blood pressure during inspiration characteristic of cardiac tamponade
41
Why does pulses paradoxus occur?
Due to ventricular interdependence
When the right heart fills during pericardial tamponade the ventricle can't distend to accommodate the volume so the septum bulges into the left ventricle decreasing SV and therefor systemic blood pressure by more than 10 mmHg
42
When is right atrial collapse seen in tamponade?
In late diastole
| Early systole
43
When does RV collapse occur in tamponade?
In early diastole
44
How long since a patient had an MI should they have elective surgery delayed?
1 month
45
What ECG lead is most sensitive for MI?
Lead V
46
Where is lead V placed?
The anterior axillary line of the 5th intercostal space
47
What is lead II sensitive for?
P wave characteristics
| Arrhythmias
48
What is the most common causes of MI?
Plaque ruptures
| Oxygen supply imbalance
49
What is the most common cause of intraoperative MI
Oxygen supply imbalance
50
How much air entrainment does it take for a fatal air lock situation?
3-5 ml/kg
| 10-15 ml/kg of CO2
51
What does the RCA supply?
```
Inferior wall of the LV
lateral and posterior walls of RV
1/3 of inter ventricular septum + posteromedial papillary muscle (PDA) in 85% of people
AV node
SA node (60%)
```
52
What does it mean if someone has a left dominant coronary system?
In 15%, the PDA comes off the LCX. This is left dominant
PDA gives off AV nodal artery
53
What does the LAD supply?
The anterior wall of heart
Inter ventricular septum
Bundle branches and Purlinje system
54
What does LCX supply?
The posterior and lateral walls of the LV
55
What do you do in unstable Torsades?
Unsynchronized cardioversion
56
What would be first line measures in a hypotension patient with HOCM?
Increase preload
| Avoid inotropes and vasodilation
57
What cautery should be used with an active AICD?
Bipolar and short bursts
Also, place dispersive pad near the surgical field
58
What happens to an AICD with a magnet?
It will disable the anti-tachy arrhythmia therapy
| - must interrogate after surgery!
59
What increases UOP in CPB?
Mannitol in the priming solution
Pulsation perfusion
Maintaining MAP
60
What are the whole blood concentration of heparin sufficient for CPB?
3-4 U/ml
61
What is a normal ACT?
110-140 seconds
62
What is adequate ACT for CPB?
400-480 seconds
63
What factors decrease the reliability of an ACT?
Hypothermia
| Hemo dilution
64
Who is resistant to heparin?
Those with anti thrombin 3 deficiency
| Those who have had 2-4 units of FFP
65
What does cardioplegic solution do to the resting membrane potential of the cardiac myocytes?
Makes it more positive and makes cells depolarize
After depolarization, the potassium rich solution establishes a new resting value that is less negative than before so cells cannot fully repolarize. This inactivates voltage gated sodium channels
66
What phase does cardioplegic arrest the heart in?
Diastole
67
What does blood based cardioplegic solution do?
Enhances oxygen carrying capacity and free radical scavenging so enhanced recovery of ventricular function and less periop MIs
68
How much does myocardial oxygen consumption decrease by with hypothermia?
50% for every 10 degrees
69
What else does hypothermic cardioplegic solution do?
Increases the time the myocardium can tolerate ischemia
70
What are the adverse effects of hypothermia?
```
Myocardial edema
Phrenic nerve injury
Citrate toxicity
Impaired oxygen dissociation
Increased plasma viscosity
Decreased RBC formability
```
71
What has been shown about warm cardioplegic
Less atrial fib, use of balloon pump, low CO syndrome, periop MI
72
What is retrograde cardioplegia?
Placing a balloon tipped catheter in the coronary sinus
73
What is ante grade cardioplegia?
Putting it in between the aortic cannula and the aortic valve OR
putting it in the coronary ostia
74
In what conditions may retrograde cardioplegia need to be used?
Aortic insufficiency
AV surgery
Severely stenosis coronary arteries
75
What is the drawback of retrograde cardioplegia?
Inadequate delivery to the free wall of the RV and posterior third of the septum
76
What is the resting membrane potential of a normal cardiac myocyte?
-90mV
77
What is the resting membrane potential of a cardioplegic cardiac myocyte?
-60 mV
78
What is McConnell's sign on TEE?
RV mid-free wall akinesia with spared apex
Finding of PE
79
What are some TEE findings of pulmonary embolism?
Dilated coronary sinus, right atrium, hepatic veins, RV, tricuspid regurg, bulging/flattening of septum
80
What is a type III protamine reaction?
Pulmonary HTN + RV FAILURE mediated by heparin-protamine complexes and TXA2
81
What is a type I protamine reaction?
Direct histamine or nitric oxide release
Happens with rapid administration
82
What is a type II protamine reaction?
IgE mediated anaphylaxis
A - true anaphylaxis
B- immediate anaphylactoid reaction
C - delayed anaphylactoid reaction
83
What patients may be at increased risk for type II protamine reaction?
Diabetics taking NPH
Fin fish allergy
Prior protamine exposure
84
What is the treatment for type III protamine reaction?
```
Cessation of protamine infusion
Reinstate CPB
Intropes (milrinone, isoproterenol)
Nitric oxide for the Pulm HTN
Small dose of heparin to reduce the heparin-protamine complex sizes
```
85
What does fenoldopam do?
Increases renal and splanchnic blood flow
Decreases peripheral vascular resistance
Diuresis and natriuresis
Increase intraocular
86
What are the contraindications to IABP?
```
Aortic regurgitation
Aortic dissection
Aortic stent
Aortic aneurysm
Severe bilateral PVD
Aortic or Ilio-femoral bypass grafts
Tachyarrythmias
Uncontrolled sepsis
Uncontrolled bleeding
```
87
What are the indications for IABP?
Improved coronary perfusion (increases diastolic pressure, decreases afterload)
```
Cardiogenic shock
Refractory ventricular arrhythmias
Refractory unstable angina
Decompensated systolic heart failure
Cardio support for procedure
Decompensated aortic stenosis
```
88
How does IABP work?
It inflates during diastole and deflates right before systole so it augments diastolic pressure and therefore coronary perfusion pressure and decreases afterload
This decreases myocardial workload and oxygen consumption
89
When should the IABP be deflated on ECG.
At the peak of the R wave which signals the start of systole
90
When should the balloon inflate?
The start of diastole, so the middle of the T wave (right after closure of the aortic valve)
91
Who should get antibiotic prophylaxis?
1. Prosthetic valves
2. Previous endocarditis
3. Palliative shunts and conduits
4. Unrepaired cyanotic heart lesions
5. Repaired congenital heart problems with residual defects
6. Cardiac transplant with valvular disease
7. Respiratory tract procedures that break the mucosa
92
What are the absolute contraindications to TEE probe placement?
```
Esophageal webs/strictures
Esophageal tumor
Scleroderma
Malloryl-Weiss tear
Zenker diverticulum
Recent esophageal variceal bleeding
Active upper GI bleeding
Recent upper GI surgery
Esophagectomy
Perforated viscus
```
93
What is the medication of choice to prevent arrhythmia in patients with prolonged QT?
Beta blockers
94
What is the treatment for patients with prolonged QT that are refractory to medication?
Pacemakers
95
How long of a QT is an indication for an ICD.
Greater than 550
96
Why are centrifugal pumps preferred over roller pumps?
Less blood destruction, lower risk of air emboli, lower line pressures, elimination of wear and spallation
97
What is Beck's triad?
Hypotension
Increased venous pressure
Muffled heart sounds
98
What should you use to induce someone with pericardial tamponade?
Etomidate or ketamine
Must maintain SVR and sympathetic stimulation
99
Why might you do an awake intubation for pericardial tamponade?
To improve venous return to the heart by avoiding induction drugs and positive pressure ventilation
100
Which papillary muscle is more likely to rupture and why?
Posteromedial papillary due to the single blood supply (RCA or LCX)
101
What supplies the anterolateral papillary muscle?
LAD and LCX
102
Where do you see air emboli most often in CPB?
RCA due to its superior orientation when the patient is supine
103
How can you treat protamine induced hypertension?
Milrinone
Epinephrine
Nitroglycerin
104
What is vasoplegia syndrome?
Decreased SVR (<1600), Resistance to vasopressors , High cardiac output (2.5) within the first 4 postop hours
105
What are the treatments for vasoplegia syndrome?
Methylene blue
| Vasopressin
106
What mediates type III protamine reactions?
Thromboxane A2
| - released from platelets and macrophages stimulated by protamine-heparin complexes
107
What is type II protamine reactions mediated by?
IgE - anaphylactic reaction
108
What mediates type I protamine reaction ?
Histamine
109
What is the a wave on CVP tracing?
Atrial contraction
110
What is the c wave on CVP tracing?
Tricuspid valve bulging into the right atrium during RV isovolumic contraction
111
What is the X descent in CVP tracing?
Tricuspid valve descends in the RV with ventricular ejection
112
What is the V wave on CVP tracing?
Venous return to the right atrium
113
What is y descent?
Atrial emptying in the RV through the open tricuspid
114
What is a "cannon a wave"?
A large a wave without the c wave
115
What does a cannon a wave mean?
AV dissociation - atrium is contracting against a closed triscuspid valve
116
What would CVP tracing look like with atrial fibrillation?
No "a" wave
117
What would CVP tracing look like in tricuspid regurg?
Tall c and v waves
| Loss of X descent
118
What would tricuspid stenosis look like?
Tall a wave
Tall v wave
Loss of y descent
119
What would RV ischemia look like in CVP tracing?
Tall a and v waves
Steep X and y descent
M or W configuration
120
What would pericardial constriction look like in CVP tracing?
Tall a and v waves
Steep X and y descent
M or W configuration
121
What would cardiac tamponade look like on CVP tracing?
Dominant X descent, minimal y descent
122
What intervention should be done if a patient is found to have severe CAD but needs operation within 14 days and there is a high risk of bleeding?
Balloon angioplasty
123
What intervention should be done if a patient is found to have severe CAD but needs operation within a few weeks and there is a high risk of bleeding?
Bare metal stent placement and dual anti-platelet therapy for 4-6 weeks
Continue ASA only in the perioperative period if 30 days from stent placement
124
What intervention should be done if a patient is found to have severe CAD but needs operation and there is a low risk of bleeding?
Do DES and continue anti platelet therapy in perioperative period
125
What intervention should be done if a patient is found to have severe CAD and the case is purely elective?
Get a DES + dual anti platelet therapy for one year
| Continue ASA in the perioperative period
126
What do you do with therapy if the surgery cannot wait for 30 days after placement of bare metal stent?
Continue dual anti platelet therapy in the periop period
127
What do you do with therapy if the surgery cannot wait for 365 days after placement of drug eluting stent?
Continue dual anti platelet therapy in periop period
128
What is the cardio toxicity of doxorubicin correlate with?
Cumulative dose
| Peak plasma concentration
129
What dose of doxorubicin is related to a 10% rise in incidence of cardio toxicity?
550 mg/m2
130
What drug increases the toxicity of doxorubicin?
Trastuzumab
131
What conditions are associated with a large R wave in V1?
```
Muscular dystrophy
WPw
RVH
Right atrial enlargement
RV strain
Posterior wall MI
```
132
What factors make thermodilution unreliable?
```
Timing of the injectate with the respiratory cycle (inspiration = colder)
Too-slow injection
Low flow states
Wedged catheter
Clot
Measurement during electrocautery
```
133
What will reducing the volume of injectate do to the measured CO?
Overestimate it by 5-10% for every 0.5 ml
134
What side effects does inamrinone cause?
Hepatic necrosis
| TCP
135
What is the treatment for WPW?
```
Procainamide - class 1a sodium channel blocker
It slows the conduction down so that it increases the refractory period of the myocardium, but preserves the AV node
```
136
Why is digoxin bad in WPW?
Because it increases the atrial conduction causing increased aberrant pathway
137
Why is adenosine bad in WPW?
It blocks the AV nose increasing aberrant pathway conduction
138
Where does an IABP sit?
In the proximal aorta just distal to the left subclavian artery
139
What are the metabolic changes in aortic cross clamping?
```
Decreased oxygen consumption
Increased SvO2
Decreased CO2 production
Increased catecholamines
Respiratory alkalosis
Metabolic acidosis
```
140
What is asynchronous mode in a pacemaker?
DOO, VOO, AOO
141
What is DOO?
It is asychronous mode meaning the pacemaker will pace at whatever rate it is set on
Dual paced, but not sensing or inhibiting
142
When is asynchronous mode dangerous?
When the patient's rate is higher than the pacemakers because of R on T phenomenon
143
What dose of heparin has been shown to be effective in cases of heparin resistance?
75 U/kg
144
What is the action of anti thrombin III?
Inhibits thrombin, factor Xa and other clotting factors
145
How does heparin work?
It binds heparin which activates it and causes a conformational change that allows for higher affinity for thrombin
146
What are the risk factors for antithrombin III deficiency?
Platelets >300 K
Age over 65
Preop heparin
147
What does PCC (prothrombin complex concentrate) contain?
Factor II, VII, IX, X
148
When is PCC used?
Emergently in intracranial bleed for reversal of warfarin
149
What are the hemodynamic goals for aortic regurgitation?
Decreased afterload
High normal heart rate
Maintaining contractility
150
What are the hemodynamic goals for mitral regurgitation?
Reduced afterload to improve forward flow
151
What are the risk factors for mitral regurgitation?
```
Advanced age
Posterior or inferior wall MI
Multi vessel disease
Prior MI
Infarct extension
Recurrent ischemia
```
152
What is ACT?
It is a functional assessment of the intrinsic and common coagulation pathway
153
What is the Betzold-Jarisch reflex?
Paradoxical reflexive bradycardia caused by left ventricular distention mediated by stretch fibers via the vagus nerve in the setting of hypotension in anaphylaxis
154
What is the Bainbridge reflex?
Increased heart rate due to atrial stretch receptors
155
What pacemaker setting is appropriate for someone with permanent atrial fibrillation?
VVI
156
What pacemaker setting is appropriate for someone with sick sinus syndrome?
AAI
157
What should you do if someone is pacemaker dependent going to surgery?
Place in asynchronous mode so that electromagnetic interference is not read a intrinsic cardiac activity by pacemaker and it stops pacing
158
Why do we disable the tachyarrythmia mode in an ICD for operation?
So that electromagnetic interference isn't detected as cardiac activity that needs to be shocked and patient gets R on T
159
What mode of pacemaker can cause R on T when only a ventricular lead?
DDD due to post-atrial ventricular blanking
160
A high grade stenosis lesion in what vessel would cause AV block?
PDA
161
What is the major landmark for a stellate ganglion block?
Transverse process of C6
162
What should be used for nausea after a high spinal block?
Atropine because it is likely due to more peristalsis after sympathectomy
163
What artery does the middle cardiac vein run with?
PDA
164
Where does the great cardiac vein run?
Along the AV groove with the LAD
165
Where does the anterior cardiac vein run?
With RCA
166
Where does 85% of coronary blood flow to LV empty into?
Coronary sinus
167
What vein drains the RV?
Anterior cardiac vein
168
Where does 15% of LV blood flow drain into?
Thebesian veins
169
What artery does the middle cardiac vein run with?
PDA
170
Where does the great cardiac vein run?
Along the AV groove with the LAD
171
Where does the anterior cardiac vein run?
With RCA
172
Where does 85% of coronary blood flow to LV empty into?
Coronary sinus
173
What vein drains the RV?
Anterior cardiac vein
174
Where does 15% of LV blood flow drain into?
Thebesian veins
175
What patients should be started on a beta blocker perioperatively?
Patients with 3 or more risk factors for CAD/MI and having high risk surgery
176
What is the equation for wall tension?
Wall tension = LVEDP X radius (of ventricle)/ 2 X wall thickness
177
What are the three main determinants of myocardial oxygen demand?
Heart rate
Contractility
Wall tension
178
How does LVH help decrease myocardial oxygen demand?
Decreases wall tension by increasing wall thickness
179
What is ST depression a sign of?
Acute sub endocardium ischemia
180
What is ST elevation a sign of?
Transmitral ischemia or injury
181
What are the characteristics of a pathological Q wave?
At least 1 mm or 0.04 ms in width and 1/3 height of the QRS
182
Why is epinephrine the drug of choice in ACLS.
The alpha mediated vasoconstriction improved coronary and cerebral perfusion pressure
183
What is a prominent R wave suggestive of?
```
RVH
RV strain (with ST changes)
Posterior wall MI
WPW
Right atrial enlargement
Muscular dystrophy
```
184
How much SV does the atrial kick provide in a patient with a normal heart?
20%
185
How much SV does the atrial kick provide to a patient with AS?
40%
186
What is the ideal heart rate for someone with AS?
55-70 bpm
187
How much time should pass before a patient who had a major cardiac event gets noncardiac surgery?
Greater than 60 days
188
Which ion are myocytes permeable to?
Potassium
189
Which ion are myocytes impermeable to?
Na and Ca
190
How does the Na-K ATPase pump work?
Moves K in, Na out
191
What is the normal resting potential of a cardiac myocyte?
-80-90 mV
192
What maintains the cardiac action potential?
Voltage gated calcium channels (L-type)
193
Where is the SA node?
At sulcus terminalis, posteriorly at the junction of the right atrium and SVC
194
What causes the SA node to fire?
Constant leaking of Na channels, making the membrane potential less negative (toward threshold)
195
Where is the AV node?
In the septal wall of the right atrium
| Anterior to the opening of the coronary sinus and above the insertion of the septal leaflet of the tricuspid
196
What are the three regions of the AV node?
N (middle) - no automaticity
NH (lower junctional)
AN (higher junctional)
197
Why is there a delay in the AV node?
It is mediate by L-type calcium channels
198
What ion channel is responsible for the ventricular depol?
Sodium channels
199
Which drugs bind L-type calcium channels?
Nifedipine
Verapamil
Dilt
200
What is the mechanism of contraction?
Intracellular calcium binds troponin C --> conformational change --> exposed sites on actin --> actin/myosin bind
201
When does relaxation occur?
When Ca is pumped back into SR by Ca-Mg- ATPase and extracellularly by an ATPase
202
What ion is myosin dependent on?
Magnesium
Because the active site on myosin functions as a Mg-dependent ATPase
203
How does sympathetic stimulation affect contractility?
B1 mediated increase in camp results in additional calcium channels
204
How do phosphodiesterase inhibitors enhance contractility?
By preventing the breakdown do cAMP, thus increasing calcium receptors and thus calcium influx
205
How does digitalis increase contractility?
By inhibiting the Na-K ATPase pump, allows Calcium to buildup in cell
206
How does glucagon increase contractility?
By increasing cAMP by nonadrenergic pathway
207
How does levosimendan work?
Binds to troponin C increasing its sensitivity to Ca
208
How does acidosis affect contractility?
Slows calcium channels
209
What is the sympathetic innervation to the heart?
T1-4 via the stellate ganglion
210
What is early diastolic compliance?
Rate of relaxation
211
What is late diastolic compliance?
Passive stiffness of the ventricles
212
What factors influence early diastolic compliance?
HTN
Aortic stenosis
A synchrony
213
What factors influence late diastolic compliance?
```
Pericardial disease
Extensive dissension of contralateral ventricle
Increased airway pressure
Pleural pressure
Tumors
Surgical compression
```
214
What is normal pulmonary vascular resistance?
50-150 dyn3/
215
What does the initial rise of the arterial line represent?
The change in ventricular pressure over time
216
What are the things that determine diastolic function?
Isovolumetric relaxation time
The peak of early diastolic flow (E) to peak atrial systolic flow (A)
Deceleration time of E
217
What e' wave peak velocity is associated with impaired diastolic filling?
Less than 8cm/sec
218
What is a normal E/a ratio?
0.8-1.2
219
What is a normal deceleration time of E?
150-300 ms
220
What is the E/a ratio of stage II (pseudo normalization)?
0.8-1.2
221
What is the E/a ratio of stage I (impaired)?
<0.8
222
What is the E/a ratio of stage III
>1.2
223
What is the deceleration time of E in stage I DD?
>250 ms
224
What is the deceleration time of stage III DD?
Less than 150 ms
225
What is the sequence of coronary blood flow?
Epicardium-->endocardium vessels --> right atrium via coronary sinus and anterior cardiac veins
Some blood goes directly to chambers via thebesian veins
226
How does coronary perfusion pressure work?
It is regulated by the myocardium according to deman between perfusion pressures of 50-120mmHg
227
What adrenergic receptors are present in coronary vessels?
Beta 2 and alpha
228
What is the most important determinant of myocardial blood flow?
Myocardial oxygen demand
229
How much oxygen does the myocardium extract from the blood? What are the implications of this?
65%, the myocardium cannot compensate for reductions in blood flow by increasing oxygen extraction. Must increase coronary blood flow instead
230
What is the most taxing thing that require oxygen?
Pressure work
231
How are volatile anesthetics helpful in heart failure?
Decrease preload and afterload thereby decreasing myocardial oxygen demand.
Protects against reperfusion injury
Enhance recovery of stunned myocardium
232
Why does E/a ratio decrease in stage I?
Because early filling is decreased because the pressure gradient is decreased fro, the atrium to ventricle, so the peak velocity of E is reduced, but the atrium contracts normally.
233
Why does the E/a ratio in stage II "normalize"?
Because as diastolic dysfunction progresses, the atrial pressure increases restoring the gradient between atrium and ventricle
234
Why does stage III diastolic dysfunction have an increased E/a ratio?
The ventricle is so stiff that early filling is quick and the atrium can barely contract against the pressure and thus contributes little to filling
235
What kind of valve disorder does a prominent a wave and a decreased y descent indicate?
Mitral stenosis
236
What does a notched P wave on EKG mean?
May indicate mitral stenosis
237
What valve area is considered severe mitral stenosis?
Less than 1.5 cm
238
What is a normal mitral valve area?
4-6 cm
239
In mitral stenosis, what does the PCWP represent?
The transvalvular gradient
240
How much regurgitate volume is considered severe?
Greater than 60%
| RSV Greater than 65 ml
241
What hemodynamics should be avoided in MR?
Slow heart rate and acute increases in afterload
| Volume overload
242
What valve disorder is associated with a large v wave and a rapid y descent?
Mitral regurg
243
What is the v wave proportional to?
Pulmonary blood flow and regurgitant volume
