CARDIOVASCULAR- Physiology Flashcards
Which ia the formula to calculate Cardiac output?
Stroke volume X heart rate
Using Fick principle how do you calculate Cardiac output?
CO= Rate of O2 consumption
———————————————————
arterial O2 content- venous O2 content
What is the mean arterial Pressure?
Cardiac output X Total peripheral resistance
Formula to calculate Mean arterial pressure
MAP= 2/3 diastolic pressure+ 1/3 systolic pressure
How do you calculate Pulse pressure?
Pulse pressure= Systolic pressure- diastolic pressure
What is the pulse pressure?
Is proportional to Stroke volume, inversely proportional to arterial compliance
In order to calculate Stroke volume we need this formula
SV= End Dyastolic Volume- End systolic Volume
During early stege of excercise how is Cardiac output maintan?
↑ Heart rate and ↑ Stroke volume
During late stages of excercise how is the Cardiac output affected?
↑ Heart rate only (Stroke volume plateu)
How is Diastole affected with ↑ Heart rate?
Diastole is prefetentially shortened with ↑ Heart rate
How is Cardiac Output affectedif Diastole is shortened with ↑ Heart Rate?
Less filling time → ↓ CO (eg Ventricular tachycardia)
When is Pulse pressure increased?
In hyperthyrodism, aortic regurgitation, arteriosclerosis, obstructive apnea (sympathetic tone), exercise (transient)
In these situation pulse pressure is decreased
Aortic stenosis, cardiogenic shock, cardiac tamponade, and advanced hear failure
Who affects Stroke volume?
By Contractility, Afterload, Preload
When does Stroke volume increases?
↑ contractility, ↑ preload or ↓ afterload
When do Contractility and Stroke volume (SV) increase?
Cathecholamines
↑ increased intracellular Ca2+
↓ extracellular Na+ (↓ activity of Na+/Ca2+ exchanger)
Digitalis
How digitalis increase contractility?
Blocks Na+/ K+ pump → ↑ intracellular Na+ → ↓ Na+/Ca2+ exchanger → ↑ intracellular Ca2+
Explain the mechanism of how cathecolamins increase contractility
↑ activity of Ca2+ pump in sarcoplasmic reticulum
In these situations Contractility and Stroke volume is decreased
β 1 blockade (↓cAMP) Heart failure with systolic dysfunction Acidosis Hypoxia/ Hypercapnea (↓ PO2/ ↑ PCO2) Non dihydropyridine Ca2+ blockers
These are normal situations that increase Stroke volume
Anxiety, excercise, pregnancy
How does a failling heart affects Stroke Volume?
↓ Stroke Volume (both systolic and diastolic dysfunction)
Which situation increase Myocardial O2 demand?
↑ afterload
↑ contractility
↑ Heart rate
↑ ventricular diameter (↑ wall tension)
Which measured is approximated to Preload?
Ventricular End dyastolic Volume (EDV)
Preload depends on this factors
Venous tone and circulating blood volume
What decreases preload?
Venodilators (nitroglicerin)
Which measured is approximated to Afterload?
By MAP (Mean Arterial pressure)
What does Laplace’s law states related to Afterload?
Relation of Left Ventricle size and afterload
Laplace’s law formula
Wall tension = pressute X radius
—————————-
2 X wall thickness
Law related to After load
Laplace’s Law
What is the result of ↑ After load?
LV compensates for ↑ Afterload by thickening (hypertrophy) to ↓ wall tension
This drug Decreases just Afterload?
Vasodilators (hydralazine) ↓ Afterload (arterial)
These drugs decrease both Atferload and Preload
ACE inhibitors and ARBs
Which chronic situation can lead to Left ventricle hypertrophy?
Chronic hypetension (↑ MAP)
Formula to calculate Ejection Fraction
SV EDV- ESV
EF= ——- = —————-
EDV EDV
What does Left ejection means?
Index of ventricular contractility
Which is the normal value of Ejection Fraction?
> 55 %
When is Ejection Fraction decreased?
In systolic heart failure
How is Ejection fraction in dyastolic heart failure?
Normal
Force of contraction is proportional to…
End diastolic length of cardiac muscle fiber
What is End diastolic length of cardiac muscle fiber?
Preload
When is Contractility decreased?
Loss of myocardium (eg. MI), β blocker, calcium channel blockers, dilated cardiomyopathy
Which are the parameters measured in Starling curve?
Stroke Volume (or Cardiac Output) compared to Ventricular End diatolic Volume (Preload)
In which situation is Starling curve above normal range
Excercise
When is Starling curve below normal range?
CHF+ digoxin
CHF
What is ΔP?
Changes in pressure (pressure gradient)
What is Q?
Flow
Meaning of R
Resistance
Formula to calculate Pressure gradient
Pressure gradient (ΔP) = Flow (Q) X Resistance (R) ΔP = Q X R
Which other formula is similar to ΔP = Q X R?
Ohm’s law: ΔV = IR
In order to calculate Resistance what is needed?
driving pressure (ΔP) 8 n (viscosity) X length
R= ——————————– = ———————————–
flow (Q) πr4
How is Total resistance of vessels in series calculated?
TR= R1+ R2+ R3…..
For Total resistance of vessels in parallel this is the Formula
1 1 1 1
—- = — + — + — ….
TR R1 R2 R3
On what mostly depends the viscosity?
On Hematocrit
When is Viscosity increased?
Polycythemia
Hyperproteinemic states (multiple myeloma)
Hereditary spherocytosis
When is viscosity decreased?
Anemia
How does pressure gradient drives flow?
From high pressure to low pressure
What is directly proportional to resistance?
Directly proportional to viscosity and vessel
Resistance is inversely proportional to….
the radius to the 4th power
They regulate capillary flow
Arterioles account for most of Total Peripheral Resistance
What happens in inotropy?
Changes in contractility → altered Cardiac Output for a given Right Atrium pressure (preolad)
They are inotropy positive
Catecholamines, digoxin
Examples of inotropy negative
Uncompensated heart failure, narcotic overdose
What causes Venous return changes?
Altered Rigth Atrium pressure for a given Cardiac output. Mean systemic pressure changes with volume/ venous tone.
In venous return, when does the mean systemic pressure changes?
With volume/ venous tone
Example of Positive venous return
Fluid infusion, sympathetic activity
Name situation that negatively stimulates venous return
Acute hemorrhage, spinal anesthesia
What causes Total peripheral resistance changes?
Altered Cardiac Output at a given Rigth Atrial pressure; however, mean systemic pressure is unchanged
What causes positive total peripheral resistance?
Vasopresors
In this situation exist negative total peripheral resistance
Exercise, AV shunt
How are cardiac and vascular functions affected by excersice?
Reinforcing:
↑ inotropy
↓ Total peripheral resistance
To maximize Cardiac Output
How are cardiac and vascular functions affected by heart?
↓ inotropy
Fluid retention to ↑preload to maintain Cardiac Output
Which are the phases of Pressure volume loops and cardiac cycle?
1) Isovolumetric contraction
2) Systolic ejection
3) Isovolumetric relaxation
4) Rapid filling
5) Reduced filling
When does the isovolumetric contraction occurs?
Period between mitral valve closing and aortic valve opening
When is the period of highest O2 consumption?
During isovolumetric contraction
Period of Systolic ejection
Period between aortic valve opening and closing
Period between aortic valve closing and mitral valve opening
Isovolumetric relaxation
Period just after mitral valve opening
Rapid Filling
Reduced Filling
Period just before mitral valve closing
What does S1 means?
Mitral and tricuspide valve closure
Where is the loudest area to hear S1?
Mitral area
What is the meaning of S2?
Aortic and pulmonary valve closure
Where is better heard S2?
Left Sternal border
What does S3 means?
In early diastole during rapid ventricular filling phase
Which situations are associated to S3?
↑ Filling pressures (eg. mitral regurgitation, CHF) and common in dilated ventricles
When is S3 consider normally?
Normal in children and pregnant women
Alternative name for S4?
Atrial kick
When is S4 heard?
In late diastole
What does S4 means?
High atrial pressure
If we heard a S4 what should we think?
Associated with ventricular hypertrophy. Left atrium must push against stiff LV wall
Which are the four waves in Jugular venous pulse?
a, c, x, v, y
What does a wave in Jugular venous pulse means?
Atrial contraction
Which is the meaning of c wave in Jugular venous pulse?
RV contraction (closed tricuspid valve bulging into atrium)
What does x descent in Jugular venous pulse means?
Atrial relaxation and downward displacement of closed tricuspid valve during ventricular contraction
When is x descent absent?
In tricuspid valve
v wave in Jugular venous pulse means
↑ right atrial pressure due to filling against closed tricuspid valve
Meaning of y descent wave
Blood flow from Right Atrium to Right Ventricle
What happens in normal heart splitting sound?
Inspiration → drop in intrathoracic pressure→ ↑ venous return to the RV→ ↑ RV stroke volume → ↑ RV ejection time→ delayed closure of pulmonary valve
What else happens during insipiration?
↓ pulmonary impedance (↑ capacity of the pulmonary circulation)
What contributes to delayed closure of pulmonic valve?
↓ pulmonary impedance (↑ capacity of the pulmonary circulation)
How is represented Normal splitting?
Expiration I I I
S1 A2 P2
Inspiration I I I
When is heard the wide splitting of Heart sounds?
Seen in conditions that delayed RV emptying:
Pulmonic stenosis
Right bundle branch block
What does delay in RV causes?
Delayed pulmonic sound (regardless of breath)
How is wide splitting heard?
An exaggeration of normal splitting
Represent the wide splitting
Expiration I I I
S1 A2 P2
Inspiration I I I
When is Fixed splitting seen?
Atrial Septal Defect
Which are the repercussions of Atrial Septal Defect?
Atrial Septal Defect → left to right shunt → ↑ Ra and RV volumes → ↑ flow through pulmonic valve such that, regardless of breath, pulmonic closure is greatly delayed
How is the fixed splitting pattern?
Expiration I I I
S1 A2 P2
Inspiration I I I
When is paradoxical splitting heard?
In conditions that delay LV emptying
Which situations delay LV empting?
Aortic stenosis, left bundle branch block
What is the difference of a normal splitting and paradoxical spliting?
Normal order of valve closure is reversed so that P2 sounds occurs before delayed A2 sound
This is the reason why is a paradoxical splitting
On insporation, P2 close later and moves closer to A2, thereby “paradoxycally” eliminating the split
Schematically how is Paradoxical splitting?
Expiration I I I
S1 P2 A2
Inspiration I II
What can be heard in Aortic area?
Systolic murmur
Systolic murmurs in Aortic area?
Aortic stenosis
Flow murmur
Aortic valve sclerosis
What can be heard in left sternal border?
Diastolic and Systolic murmurs
You might identify these diastolic murmur pathologies in the left sternal border
Airtic regurgitation
Pulmonic valve regurgitation
You might identify these systolic murmur pathology in the left sternal border
Hypertrophic cardiomyopathy
what can be heard in Pulmonic area?
Systolic ejection murmur
What can a systolic ejection murmur in pulmonic area mean?
Pulmonic stenosis Flow murmur (physiologic murmur)
This is what can be heard in Tricuspid area
Pansystolic murmur
Diastolic murmur
Pansystolic murmur in Tricuspid area can mean…
Tricuspid regurgitation
Ventricular Septal defect
Diastolic murmur in Tricuspid area can mean…
Tricuspid stenosis
Atrial septal defect
Mitral area sounds can be classified as
Systolic and Dyastolic murmurs
Systolic murmur in mitral area means…
Mitral regurgitation
Diastolic murmur in Mitral area means…
Mitral stenosis
How can a Atrial Septal Defect be presented?
Pulmonary flow murmur (↑ flow across tricuspid); blood flow across the actual ASD does not cause a murmur because there is no pressure gradient
How the murmur of Atrial septal defect can evolve?
The murmur later progresses to a louder diastolic murmur of pulmonic regurgitation from dilation of the pulmonary artery
During inspiration how are heart sounds modified?
↑ intensity of right heart sounds
What is the effect of Hand grip maneuver?
↑ systemic vascular resistance
What can be heard with Hand grip maneuver?
↑ intensity of MR, AR, VSD murmurs
↓ intensity of AS, hypertrophic cadiomyopathy murmurs
How can Had grip maneuver affect Mitral valve prolapse sounds?
↑ murmur intensity, later onset of click/murmur
When is better apreciated Valsalva maneuver?
phase II
What is the effect of Standing in systemic circulation?
↓ venous return
If Valsalva maneuver or Standing is realizaed Which murmurs are affected?
↓ intensity of most murmurs (including AS)
Which murmurs are ↑ with Valsalva maneuver or Standing?
Hypertrophic cardiomyopathy murmur
How can Valsalva maneuver or Standing affect Mitral valve prolapse sounds?
↓ murmur intensity, earlier onset of click/murmur
Which are the effects of Rapid squating?
↑ venous return, ↑ preload, afterload with prolongued squating
What murmur is ↓ in intensity with Rapid squating?
Hypertrophic cardiomyopathy murmur
Which murmur is ↑ in intensity with Rapid squating?
AS (aortic stenosis)murmur
How can Rapid squating affect Mitral valve prolapse sounds?
↑ murmur intensity, later onset of click/murmur
What pathologies does Systolic heart sounds include?
Aortic/ pulmonic stenosis, Mitral/ tricuspid regurgitation, ventricular septal defect
These pathologies are included in Diastolic heart sounds
Aortic/ pulmonic regurgitation, mitral/tricuspid stenosis
How is Mitral/Tricuspid regurgitation heard?
Holosystolic, high pitched blowing murmur
Where is better heard mitral?
Loudest at apex and radiates toward axilla
What enchance Mitral sounds?
By maneuvers that ↑ Total peripheral resistance
Which are common reasons of Mitral regurgitation?
Ischemic heart disease, Mitral Valve prolapse, Left ventricle dilation
Where is Tricuspid sound better heard?
Loudest at tricuspid areaand radiates to right sternal border
When is Tricupid enhance?
By maneuvers that ↑ Rigth Atrial return (eg inspiration)
Which is the common cause of Tricuspid Regurgitation?
Right ventricle dilation
Which pathology can cause either Mitral Regurgitation of Tricuspid Regurgitation?
Infective Endocarditis
This is the murmur caused by Aortic stenosis
Crescendo-decrescendo systolic ejection murmur
What happens in Aortic stenosis?
LV» aortic pressure during systole
Where is Aortic Stenosis better heard?
Heart base; radiates to carotids
Which pulse is seen in Aortic Stenosis? What does it means?
“Pulsus parvus et tardus”- pulsesare weak with delayed peak
Which could be the results if Aortic Stneosis?
Syncope, Angina, Dysnea on exertion
These are reasons of Aortic Stenosis
Age related calcific aortic Stenosis or Bicuspid aortic valve
What can be heard in Ventricular Septal Defect?
Holosystolic, harsh sounding murmur
Where is better heard Ventricular Septal Defect?
Loudest at tricuspid area
What accentuates Ventricular Septal Defect murmur?
Hand grip maneuver due to ↑ afterload
What is heard in Mitral Valve prolapse?
Late systolic crescendo murmur with midsystolic click
Why is Midsystolic click heard in Mitral valve prolapse?
Due to tensing of chordae tendineae
Which is the most frequent valvular lession?
Mitral valve prolapse
Where is better heard mitral valve prolapse?
Over Apex
When is better heard mitral valve prolapse?
Loudest just before S2
How is the prognosis of Mitral valve prolapse?
Usually Benign
What can Mitral valve prolapse predispose?
Infective endocarditis
Which could be the causes of Mitral valve prolapse?
Myxomatous degeneration, rheumatic fever, or chordae rupture
What predisposes an earlier apperance of Mitral valve prolapse?
Maneuvers that ↓ venous return (standing or Valsalva)
How are Heart murmurs classified?
Systolic
Diastolic
Continuous
Name systolic murmur causes
Mitral/ Tricuspid regurgitation
Aortic Stenosis
Ventricular Septal Defect
Mitral Valve prolapse
These are Diastolic murmur causes
Aortic regurgitation
Mitral stenosis
In this pathology we can heard a Continuous murmur
Patent Ductus Arteriosus
What is heard in Aortic regurgitation?
High pitched “blowing” early diastolic decrescendo murmur
When Aortic regurgitation is chronic what can be seen?
Wide pulse pressure; can present with bounding pulses and head bobbing
These are possible causes of Aortic Regurgitation
Aortic Root dilation
Bicuspid aortic valve
Endocarditis
Rheumatic fever
When is aortic regurgitation better heard?
↑ murmur during hand grip
What decreases intensity of murmur in Aortic regurgitation?
With Vasodilators
In mitral Stenosis what is heard?
Follows opening snap
Which is the reason of Opening snap in Mitral Stenosis?
Due to abript half in leaflet mition in diastole, after rapid opening due to fusion at leaflet tips
When is Mitral Stenosis heard?
Delayed rumbling late diastolic murmur
In mitral Stneosis what correlates with increased severity?
↓ Interval of between S2 and Opening Snap
This is what happens in Mitral Stenosis
LA»_space; LV pressure during diastole
Which is the most common reason of Mitral Stenosis?
Secondary to Rheumatic Fever
What could be the result of Chronic Mitral Stenosis?
Left Atrial Dilation
What enhances Mitral stenosis?
Maneuvers that ↑ Left Atrial return (expiration)
What is heard in Patent ductus arteriosus?
Continuous machine-like murmur
When is Patent ductus arteriosus murmur better heard?
Loudest at S2
Common causes of Patent ductus arteriosus
Congenital Rubella
Prematurity
Where is Patent ductus arteriosus murmur better heard?
At left infraclavicular area
Where else does Ventricular action potential takes place?
Bundle of His and Purkinje fibers
How many phases does Ventricular action potential has?
0, 1, 2, 3, 4
What happens in Phase 0 of Ventricular action potential?
Rapid upstroke and depolarization
Which channles are open in Ventricular action potential phase 0?
Voltage gated Na+ channels
This phase is known as initial repolarization in Ventricular action potential
Phase 1
Which channels interact in Phase 1 of Ventricular action potential?
Inactivation of Voltage gated Na+ channels
Voltage gated K+ channels begin to open
How is phase 2 of Ventricular action potential known?
Plateau
Which channels are affected in Plateau phase of Ventricular action potential?
Ca+ influx through voltage gated Ca2+ channels balances K+ efflux
During phase 2 of Ventricular action potential what does Ca2+ influx triggers?
Triggers Ca2+ release from sarcoplasmic reticulum and myocyte contraction
Also known as Rapid repolarization phase in Ventricular action potential
Phase 3
What happens in Rapid repolarization phase during Ventricular action potential?
Massive K+ efflux due to opening of voltage gated slow K+ channels and closure of gated Ca2+ channels
What is phase 4 of Ventricular action potential?
Resting potential
Which channels are permeable in Resting potential?
High K+ permeability through K channels
Which is the difference in channels between skeletal muscle and Cardiac muscle?
Cardiac Miscle action potential has a plateau, which is due to Ca2+ influx and K+ efflux
Myocite contraction occurs due to Ca2+ induced Ca2+ release from the sarcoplasmic reticulum
When are Cardiac nodal cells depolarize?
During Diastole
What is the result of cardiac nodal cells depolarization?
Automaticity due to If channels
What are If channels?
“Funny current” channels responsible for a slow, mixed Na+/ K+ inward current
What other difference do Cardiac cells have from Skeletal muscle cells?
Cardiac Myocytes are electrically coupled to each other by gap junctions
From how many mV does Ventricular action potential goes?
More than 0 mV to -85 mV
How much time does Efective refractory period last?
200 msec
From which phases does Efective refractory period takes place?
From phase 1 to phase 4
What is the Efective refractory period?
Is the time when the cardiac cell can’t be depolarize
Where does Pacemaker action potential occurs?
In the SA and AV nodes
What happens in Phase 0 of Pacemaker action potential?
Upstoke- Opening of voltage gated Ca2+ channels
What happens to the fast voltage gated Na+ channels in Pacemaker action potential?
Are permanently inactivated
Why are fast voltage gated Na+ channels in Pacemaker action potential inactivated?
Because of less negative resting voltage of these cells
Which is the result inactivated fast voltage gated Na+ channels in Pacemaker action potential?
Results in a slow conduction velocity that is used by the AV node to prolong transmission from the atria to ventricles
What happens in phase 2 of pacemaker action potential?
Phase 2 is absent
Which channels are affected in phase 3 of pacemaker action potential? and How?
Inactivation of Ca2+ channels and ↑ activation of K+ channels → ↑ K+ efflux
How is phase 4 of pacemaker action potential known?
Slow diastolic depolarization
What happens during phase 4 of pacemaker action potential?
Membrane potential spontaneously depolarizes as Na+ conductance ↑
Which channels are different in pacemaker action potential and Ventricular action potential?
If different from INa in phase 0
Which phase acounts as the automaticity of SA and AV nodes?
Phase 4
In the pacemaker action potential what determines the Heart rate?
The slope of phase 4 in the SA node determines Heart Rate
What is the effect of ACh/ adenosine in heart?
↓ the rate of diastolic depolarization and ↓ Heart rate
What ↓ the rate of diastolic depolarization and ↓ Heart rate?
ACh/ adenosine
These is the effect of catecholamines in heart?
↑ depolarization and ↑ Heart Rate
Who ↑ depolarization and ↑ Heart Rate?
Catecholamines
What is the effect of Sympathetic stimulation in heart?
↑ the chance that If channels are open and thus ↑ Heart Rate
From how many mV does pacemaker action potential goes?
Little less -60 to little more than 0
In electrocardiogram what does P wave means?
Atrial depolarization
Who masks Atrial repolarization in Electrocardiogram?
By QRS comlex
What does PR interval means?
Conduction delay through AV node
How much time does PR interval normally last?
< 200 msec
What is QRS complex?
Ventricular depolarization
Time that QRS normally lasts?
< 120 msec
What happens in QT interval?
Mechanical contraction of the ventricles
What is the T wave?
Ventricular Repolarization
What electrocardiogram change indicates recent MI?
T wave inversion
What happens in ST segment?
Isoelectric, ventricles depolarized
When is U wave present in electrocardiogram?
Caused by hypokalemia, bradycardia
How is the speed of conduction?
Purkinje> atria> ventricles> AV node
How are classify the Pacemakers?
SA> AV> bundle of His/ Purkinje/ ventricles
How is the conduction Pathway?
SA node→ Atria → AV node → common bundle→ bundle branches → Purkinje fibers → ventricles
Which are the characteristics of SA node?
Pacemaker inherent dominance with slow phase of upstroke
Which is the delay of AV node?
100 msec
What does the Atrioventricular delay allows?
Allows time for ventricular filling
How is the potential measured in Electrocardigram?
In mV
From how many mV RS goes?
1.0 to -0.5
What are Torsades de Pointes?
Polymorphic ventricular tachycardia, characterized by shifting sinusoidal waveforms on ECG
Which is the possible progression of Torsades de Pointes?
To Ventricular fibrillation
What predisposes to Torsades de Pointes?
Long QT interval
Who causes Torsades de Pointes?
Drugs, ↓ K+, ↓ Mg2+, other abnormalities
What is included in the treatment of Torsades de Pontes?
Magnesium sulfate
Which medicines can cause Torsades de Pointes?
Some Risky Meds Can Prolong QT Sotalol Risperidone Macrolides Chloroquine Protease inhibitors (navir) Quinidine (class Ia, also class III) Thiazides
Inherited disorder of myocardial repolarization
Congenital long QT syndrome
Which is the reason of Congenital long QT syndrome?
Typically due to ion channel defects
Which are the risks of Congenital long QT syndrome?
Increased risk of sudden cardiac death due to torsades de pointes
Which are Congenital long QT syndrome?
Romano Ward syndrome
Jervell and Lange Nielsen syndrome
Genetically which is the inheritance mode of Romano Ward syndrome?
Autosomal dominant
What is the phenotype affection in Romano Ward syndrome?
Pure cardiac phenotype (no deafness)
Congenital long QT syndrome
Inheritance mode for Jervell and Lange Nielsen syndrome
Autosomal recessive
Phenotype Characteristics of Jervell and Lange Nielsen syndrome
Sensorioneural deafness
Congenital long QT syndrome
Most common type of ventricular pre excitation syndrome
Wolff Parkinson White syndrome
What is Wolff Parkinson White syndrome?
Most common type of ventricular pre excitation syndrome
Which is the defect in Wolff Parkinson White syndrome?
Abnormal fast accessory conduction pathway from atria to ventricle bypasses tje rate slowing AV node
Which is the Abnormal fast accessory conduction pathway from atria to ventricle in Wolff Parkinson White syndrome?
Bundle of Kent
What are the results of Bundle of Kent in Wolff Parkinson White syndrome?
Ventricles begin to partially depolarize earlier, giving rise to characteristic delta wave with shortened PR interval on ECG
What is the Delta wave?
Partial Ventricles depolarization earlier
Which could be the complication of Wolff Parkinson White syndrome?
May result in reentry circuit → Supraventricular tachycardia
Which is the ECG pattern of Atrial Fibrilation?
Chaotic and erratic baseline(irregularly irregular) with no discrete P waves in between irregularly spaced QRS complexes
Which are the possible outcomes of Atrial fibrilation?
Can result in atrial stasis and lead to Thromboembolic stroke
Which are the treatments for Atrial Fibrilation?
Includes rate control, Anticoagulant, and possible pharmacological or electrical cardioversion
How is Atrial flutter seen in EKG?
A rapid succession of identical, back to back atrial depolarization waves
Which appearance do flutter waves have?
Sawtooth appearance
Which is the Pharmacological treatment for Atrial Flutter and what is its purpose?
Pharmacological conversion to sinus rhythm, Class IA, IC or III antiarrhythmics
Rate control
Which is the pharcmacological treatment for Atrial Flutter for Rate control?
β blocker or Calcium channel blockers
Definitive treatment for Atrial Flutter
Catheter ablation
On ECG what is seen in Ventricular Fibrilation?
A completely erratic rhythm with no identifiable waves
Which could be the prognosis of Ventricular Fibrilation?
Fatal arrythmia without immediate CPR and defibrillation
What happens in 1st degree AV block?
The PR interval is prolonged (> 200 msec)
How is the prognosis of 1st degree AV block?
Benign and asymptomatic
Which is the treatment for 1st degree AV block?
No treatment required
How are AV blocks Classified?
1st Degree
2nd Degree
Mobitz Type I
Mobitz Type II
3rd DegreeHow else is Mobitz Type I known?
Wenckebach
What happens in Mobitz I?
Progressive lenghtening of the PR interval until a beat is dropped (a P wave not followed by QRS complex)
Explanation of Mobitz II
Dropped beats that are not preceded by a change un the length of the PR interval (as in type I).
It is often found as 2:1 block, where there are 2 or more P waves to 1 QRS response
Which is the prognosis of Mobitz II?
Might progress to 3rd degree block
How is Mobitz often treated?
With Pacemaker
AV block known as complete block
3rd degree
What happens in 3rd degree block?
The atria and the ventricles beat independiently of each other
Which is the ECG pattern of 3rd degree block?
Both P waves and QRS complexes are present, although the P waves bear no relation to the QRS complexes
Which rate is faster in 3rd degree block?
Atrial rate is faster than the ventricular rate
How is 3rd degree block ussually treated?
With pacemaker
Which infectious disease can result in 3rd Degree block?
Lyme disease
Who produces Atrial natriuretic peptide?
Released from atrial myocytes
When do atrial mycytes produce Atrial natriuretic peptide?
in response to ↑ blood volume and atrial pressure
Which is the effect of Atrial natriuretic peptide?
Vasodilation and ↓ Na+ reabsorption at the renal collecting tubule
Which is the renal effect of Atrial natriuretic peptide?
Constricts efferent renal arterioles and dilates afferent arterioles via cGMP, promoting diuresis and contributing to “aldosterone escape” mechanism
Another name for B type natriuretic peptide
Brain natriuretic peptide
Who releases B type natriuretic peptide?
Ventricular myocytes
When is B type natriuretic peptide release from ventricular myocytes?
In response to ↑ tension
How is B type natriuretic peptide compared to Atrial natriuretic peptide?
Similar physiologic action to ANP, with longer half life
What is the purpose to measured B type natriuretic peptide in blood test?
Diagnosing Heart failure (very good negative predictive value)
This is the recombinant form of B type natriuretic peptide
Nesiritide
When is Neseritide recommended?
For treatment of Heart failure
How does aortic arch transmits to solitary nucleus?
Via Vagus nerve
Where is Solitary nucleus located?
Medulla
Which stimulates are needed for Receptors in Aortic arch to respond?
Respond only to ↑ Blood pressure
Where is carotid sinus located?
Dilated region at carotid bifurcation
How does carotid sinus transmits to solitary nucleus?
Via Glossopharingeal nerve
Which stimulates are needed for Receptors in carotid sinus to respond?
Respond to ↓ and ↑ Blood pressure
Which is the importance of Barorreceptors?
Important in the response to severe hemorrhage
From Hypotension to Increased Blood Pressure how do Barorreceptors interact?
Hypotension- ↓ arterial pressure→ ↓ strecth → ↓ Afferent baroreceptor function → ↑ efferent sympathetic firing and ↓ efferent parasympathetic stimulation → Vasocontriction, → ↑ HR, ↑ contractility, ↑ BP
Which is the chain of events caused with Carotid massage?
↑ pressure on carotid sinus → ↑strethc → ↑afferent baroreceptor firing → ↑ AV node refractory period → ↓ HR
For what do Barorreceptors contribute?
To Cushing Reaction
What is the Cushing reaction?
Triad of hypertension, bradycardia and respiratory depression
How Baroreceptors contribute in Cushing reaction?
↑ Intracraneal pressure constricts arterioles → cerebral ischemia and reflexes sympathetic ↑ in perfussion pressure (hypertension) → ↑ stretch → Reflex baroreceptor induced-bradycardia
When is consider PO2 is decreased?
< 60 mmHg
Name the types of Chemoreceptors
Peripheral
Central
In peripheral chemoreceptors who are stimulated?
Carotid and aortic bodies
In peripheral chemoreceptors what stimulates Carotic and aortic bodies?
↓ PO2
↑ PCO2
↓ pH of blood
How do Central chemoreceptors work?
Are stimulated by changes in pH and PCO2 of brain interstitial fluid, which in turn are influenced by arterial CO2
Which Chemoreceptors do not directly respond to PO2?
Central
Organ with largest blood flow
Lung
Percentage of Cardiac output that flows through Lungs?
100%
Largest share of systemic cardiac output
Liver
Highest blood flow per gram of tissue
Kidney
Largest arteriovenous O2 difference
Heart
Why is heart conisder to have Largest arteriovenous O2 difference?
Because O2 extraction is 80%
In heart what increases O2 demand?
↑ Coronary blood flow, not by ↑ extraction of O2
What is PCWP?
Pulmonary Capillary wedge pressure
Which is the purpose to measuse Pulmonary Capillary wedge pressure?
Is a goof approximation of left atrial pressure
Which is the normal range for PCWP?
< 12 mmHg
In this pahology PCWP> LV diastolic pressure
Mitral stenosis
How is Pulmonary Capillary wedge pressure meassured?
Pulmonary artery catheter (Swan Ganz catheter)
Expected pressure of Right Atrial
<5 mmHg
Pressure of Right ventricle
25/5
In Right ventricle this is the normal pressure
130/10
Expected pressure in Aorta
130/90
What is the autoregulation?
How blood flow to an organ remains constant over a eide range of perfusion pressures
Main Organs that have autoregulation
Heart Brain Kidneys Lungs Skeletal muscle Skin
Factors determining autoregulation in Heart
Local metabolites (vasodilatory): CO2, adenosine, NO
Which factor determines autoregulation in Brain?
Local metabolities (vasodilatory) CO2 (pH)
Factors determining autoregulation in Kidneys
Myogenic and tubuloglomerular feedback
Which factor determines autoregulation in Lungs?
Hypoxia causes Vasoconstriction
Which vasculature is unique in that hypoxia causes Vasoconstriction?
Pulmonary vasculature
Which pulmonary areas are perfused?
Only well ventilated areas are perfused
What is the effect of Hipoxia in the organs, other than the lungs?
Hypoxia causes dilation
Factors determining autoregulation in Skeletal muscle
Local metabolites:
Lactate, adenosine, K+, H+, CO2
Which is the factor determinining autoregulation in Skin?
Sympathetic stimulation most important mechanism- Temperature control
What do Starling forces determine?
Fluid movement through capillary membranes
Which are the factors in Starling forces?
Pc= Capillary pressure Pi= Intersticial fluid pressure πc= Plasma colloid osmotic pressure πi= Interstisial fluid colloid osmotic pressure
What does Capillary pressure does?
Pushes fluid out of capillary
Effect og Interstitial pressure
Pushes fluid into capillary
What effect does plasma colloid osmotic pressure has on capillary?
Pulls fluids into capillary
Which effect does interstitial fluid colloid osmotic pressure has?
Pulls fluid out of capillary
How is Net filtration pressure calculated?
Pnet= (Pc-Pi)- (πc-πi)
In Starling forces what is Kf?
Filtration constant
Who determines the Filtration constant?
Capillary permeability
For capillary fluid exchange What is Jv?
Net fluid flow
How do you calculate Net fluid Flow?
Jv= (Kf)(Pnet)
What is edema?
Excess fluid outflow
Which are the common causes of Edema?
↑ capillary pressure
↓ plasma proteins
↑ capillary permeability
↑ interstitial fluid colloid osmotic pressure`
Example of ↑ capillary pressure
↑ Pc; heart failure
Which cases have ↑ capillary permeability?
↑ Kf; toxins. infections, burns
Name an example of ↑ interstitial fluid colloid osmotic pressure
↑ πi; Lymphatic blockage
