Module 1: CV A&P Flashcards
Anatomy and Physiology of the Heart
The heart
* Muscular, _______ pump
* Sits left-middle in chest
* Protective covering
Pair of atria
Pair of ventricles
4 unidirectional valves
Arteries and veins
Electrical Conduction system
- hydraulic
The Wall of the Heart: Pericardium
Consists of two parts:
Fibrous Portion: ______, ________, ________ sac around the heart
Serous Portion:
* ________ layer: lining inside the fibrous pericardium
- _________ layer (Epicardium): adheres to the outside of the heart
_________ Space: lies between the parietal and visceral layers
- tough, loose- fitting, inelastic
- Parietal
- Visceral
Pericardial
Epicardium :
outer layer of the heart wall; also called the _______________
Myocardium:
Thick, contractile, middle layer of specially constructed and arranged cardiac muscle cells
If the myocardium is damaged this can cause a ____________.
Endocardium:
Lining of the interior of the myocardial wall and covers the ________________ (these help add force to the inward contraction of the heart wall).
- serous pericardium
- ”myocardial infarction”
- trabeculae carneae
Cardiac Muscle Fiber
- Principle location:
- Principle function:
- Type of control:
- wall of the heart
- pumping blood
- Involuntary
Structural Features of the Cardiac Tissues
- Nucleus: Single (sometimes double); near the center of the cell
- Striations: present
- T tubules: ______ diameter; form diads with the SR, regulate ______________.
- Sarcoplasmic reticulum: _________ extensive than in skeletal muscle
- Cell junctions: intercalated disks (______ and ________)
- Contraction style: Syncytium (mass) of fibers compress the heart chambers in slow, separate contractions (does not exhibit _____or _______); exhibits auto ________.
- large, Ca++ entry into sarcoplasm
- less
- gap junctions and desmosomes
- tetanus or fatigue; rhythmicity
Cardiac Myocyte Anatomy and Function
Sarcolemma
* __________ membrane of the cardiac muscle
- Bilayer lipid membrane containing ion channels (Na+, K+, Ca2+, Cl), active and passive ion transporters (ATPase, Na+/K+), receptors ( ex: ___,____,_____, ____), and transport enzymes (glucose transporter)
- ______________: deep invaginations, penetrate the myoplasm and facilitate rapid, synchronous transmission of cellular depolarization that initiate myocyte contraction.
- External
- beta, muscarinic cholinergic, opioid, adenosine
- Transverse (“T”) tubules
Cardiac Myocyte
- Mitochondria: generates ATP required for ______ and ______.
__________: contractile unit of the cardiac myocyte
- Contains myofilaments in parallel-cross striated bundles of thin (_______,______,____) and thick (______ and _______) fiber
- Connected in a series, have long and short axes and simultaneously _____ and ______ during contraction
- ________ contains thick and thin filaments.
- ________ contains thin filaments only
- ______ bisects the I-band
- contraction and relaxation
Sarcomere
1a. actin, tropomyosin, troponin complex
1b. myosin and proteins
- shorten and thicken
- A-band
- I-band
- Z-line
Right and Left Atria
* 2 thin, overlying sheaths of muscle
* Oriented at __________ to each other
Ventricles
3 interdigitating spiral muscle layers:
*
*
*
- right angles (orthogonal)
- Deep sinospiral
- Superficial sinospiral
- Superficial bulbospiral
Atria (Receiving Chambers)
- Left and Right chambers separated by _______.
- Alternatively relax and contract to receive blood, then push it into the lower chambers
- Atria don’t need to generate great _______ to move blood small distances so the myocardial wall of each atria is _________.
- Auricle
- interatrial septum
- pressures; thin
Supporting Role of the Atria
- Facilitate transition between ______ pressure venous to _____ pressure arterial blood flow
* Reservoirs
* Conduits
* Contractile chambers - Atrial contraction
* Establishes final ventricular SV at end-diastole (normally contributes ____-____% of this volume) - Absent or ineffective (Afib/Flutter)
* Increased activity or stress may decrease/limit _____: (decreased ABP, fatigue, syncope, exertional dyspnea or acute heart failure
- low; high
- 15-20
- CO
Functional Anatomy of the Heart
Ventricular Muscle Layers:
Subendocardial and Subepicardial layers: _____,____,______ routes from the base to the apex
* _____ the ______ axis of the LV
* Pulls the apex of the heart toward the _____
* Systolic “twisting” or “wringing” motion of the fibers
Mid-myocardium: circumferential layers
* Reduce the LV ______
* Constricts the ________, especially the LV
perpendicular, oblique, and helical
- Shorten; longitudinal
- base (book: base to apex)
- diameter
- lumen
Ventricles (Pumping Chambers)
Right Ventricle
* _______ volumes of blood, movement at ______ pressure
* Free wall of the RV ______ against the IV septum and LV
* Receives venous blood from the RA via the SVC and IVC
– Low pressure ____-_____ mmHg
– O2 saturation _____-______%
- Blood flows from the RV through the pulmonary circulation (_______resistance)
- Unable to generate the same magnitude of _______ as the LV
- Accommodates __________ more easily than LV
- Large; low
- shortens
- 2-10; 60-70
- low
- stroke work
- volume overload
Ventricles (Pumping Chambers)
Left Ventricle
* _______ pressure system
* LV stroke volume (SV) is ______ to the RV
* Pressure-volume work (stroke work) is ____-____X > RV
* ______ myocardium
- High
- equal
- 4.5-7
- Thicker
Atrioventricular Valve:
Semilunar Valves:
- Tricuspid Valve
- Mitral Valve
Pulmonary valve
Aortic Valve
5 areas for listening to the heart
Palpable Point of Maximal Impulse (PMI)
- Point in the chest where impulse of _______ is strongest
- Also called the Apical Impulse
Normally palpable
* 5th intercostal space (ICS)
* Midclavicular
PMI not where is should be?
* lateral or below 6th ICS can mean:
* Greater than 2cm in size:
* Right sternal border:
- ## left ventricle
- ventricular enlargement
- ventricular hypertrophy or dilation
- dextrocardia or situs inversus
Right & Left Coronary Arteries supply oxygen and nutrients to myocardium
which coronary arteries supply LV?
Most coronary blood flow to LV myocardium occur during:
- LAD
- LCCA
- RCA
diastole - because aortic pressure exceeds LV pressure
Anatomy of Coronary Blood Flow (CBF)
Myocardial blood supply entirely from Right and Left Coronary Art.
Blood flows from _________ to _______ vessels
Coronary sinus and Anterior cardiac veins
Thesbian veins
- epicardial to endocardial
RCA contains 4 branches:
RCA supplies
LCA contains 2 branches
LCA supplies:
Review
Mechanics of Coronary Blood Flow (CBF)
Blood flow to the LV
* Directly dependent on the difference between _____ -_______.
* Inversely related to the vascular resistance to flow
Coronary Perfusion Pressure (CPP)=Arterial diastolic pressure – LVEDP
* Difference between the Aortic pressure and the Ventricular pressure
* ____________ is more important than __________ in determining myocardial blood flow
Reduced CPP:
* Decreased ______
* Increased _______
* Increase in ________
- Aortic pressure and the LVEDP (CPP)
- Art. Diastolic pressure; MAP
- Decreased Aortic pressure
- Increased LVEDP
- Increase in HR (reduction in diastolic time)
Mechanics of Coronary Blood Flow (CBF)
During contraction, intramyocardial pressures in the LV get close to systemic arterial pressure
When that happens, the force of LV contraction can almost totally occlude the intramyocardial portion of the coronary arteries
LV is almost completely perfused during ________.
RV is perfused during _______.
Greatest intramural pressure during systole affects the ______ thus making it most vulnerable to ischemia during decreases in Coronary Perfusion Pressure (CPP)
- diastole
- systole and diastole
- endocardium
Coronary Arteries and the ECG
I - Lateral
II - Inferior
III - Inferior
aVR -
aVL - Lateral
aVF - Inferior
V1 - Septal
V2 - Septal
V3 - Anterior
V4 - Anterior
V5 - Lateral
V6 - Lateral
Review
- Coronary Blood flow normally ________ (average adult male)
- Myocardium regulates perfusion pressures between _____-____ mm Hg, beyond that blood flow becomes _______ dependent
- Changes in blood flow:
- 250 ml/min
- 60-140; pressure
- Hypoxia: causes coronary vasodilation
- Sympathetic stimulation increases myocardial blood flow from increased demand and B2 predominance activation
- Alpha1 and Beta2 present in coronary arteries
Myocardial Oxygen Balance
- Myocardial oxygen balance is determined by the ratio of oxygen ______ to oxygen _______.
- Myocardium extracts ____-____% the oxygen in arterial blood
- Increasing oxygen supply by increasing either _______ or ________ leads to increase in tissue oxygen levels
- Increasing demand alone without increasing _________ decreases tissue oxygen level
- supply; demand
- 75-80
- arterial oxygen content or coronary blood flow
- CBP (stenosis)
Factors Affecting Myocardial O2 Supply-Demand Balance
Supply determined by:
Demand determined by:
HR primary determinant of O2 consumption in heart.
Review
Cardiac cycle
Conduction System of the Heart
Cardiac Conduction System Components
Function/ Rate
Review
Normal Electrocardiogram (ECG)
P
PR
QRS
ST
QT
T
Seconds
P: 0.08 - 0.11
PR: 0.12 - 0.20
QRS: <0.10
ST: <0.12
QT: <0.38
T: <0.20
Seconds
Cardiac Events: P wave
- ______ depolarization and contraction
- Deflection caused by the passage of an electrical impulse from the SA node through the muscle of both atria
- P wave abnormalities often reflect:
- Normal:
- Atrial
- Atrial enlargement
- 0.08-.11 sec (PRI: 0.12 - 0.20 sec)
Cardiac Events: QRS complex
- Depolarization and contraction of the
- ______ node fires
- Includes depolarization of the _______
- Normal measurement:
- ventricles (ventricular systole)
- AV
- interventricular septum
- <.10 sec
Cardiac Events: T wave
- Ventricular ________
- QT interval:
- ST interval: following the QRS to beginning of T:
- repolarization
- QT: <0.38
- ST: <0.12
Cardiac Cycle
- Atrial Systole
- Isovolumetric Ventricular contraction
- Ejection
- Isovolumetric ventricular relaxation
- Passive Ventricular relaxation
Atrial Systole
- Begins with the _______(passage of electrical wave of depolarization)
- Followed by Atrial contraction or systole
- Contraction force of the atria creates a pressure gradient (high to low)
- Pressure gradient drives the movement of blood and also keeps the AV valves open
- Ventricle relaxed and start filling with blood
- Semilunar valves are closed
- P wave
Isovolumetric Ventricular Contraction
- Onset of _________.
- Coincides with the _______ of the ECG and ____________
- Iso (equality or uniformity)- Volumetric (measurement of volume)
- Intraventricular pressure begins to ______
- Ventricular pressure > Atrial pressure
- ventricular systole
- R wave; 1st heart sound
- increase
Ejection
- __________ valves open.
- Pressure in the ventricles exceeds pressure in ________.
Rapid ejection
Reduced ejection
- ____________: blood that remains in the ventricles at the end of the ejection period
- In __________, residual may exceed that ejected during systole
- Semilunar; PA/Aorta
- Residual volume
- heart failure
Isovolumetric Ventricular Relaxation
* Ventricular ________
- Between closure of the Semilunar valves and opening of the AV valves
- ___________ from the SL valves snapping shut
- Both sets of valves are closed and ventricles are relaxing
Passive Ventricular Filling
- Intraventricular pressure drops and ______ pressure increases
- __________ valves open
- Diastole
- 2nd heart sound
intraatrial; AV
LV Pressure-Volume Loop
Normal EDV is ______ ml
Normal ESV is _____ ml
SV is ____ ml
EF is _____%
- 120 ml
- 40 ml
- 80 ml
- 67
Cardiac pressures
Primary Principles of Hemodynamics
Cardiac Cycle
- Defined by _____ and _____ events
- Contraction of the atria contributes ____-____% of ventricular filling
- Waves of the atrial pressure tracing
- electrical; mechanical
- 20-30
Phase of cardiac cycle and mechanical event
RA Waveform (CVP) and ECG
- ________ – occurs with atrial contraction (absent in AFIB)
- ________- occurs with closure of the tricuspid valve
- ________– due to blood filling the atrium when the tricuspid valve is closed (Enlarged in tricuspid regurg)
- a wave
- c wave
- v wave
Right Atrial (RAP) Waveform
- Normal Value: _______ mmHg
- Right Atrial Pressure = _____
- Wave Fluctuations due to contractions
- 0-8
- CVP
Right Ventricular (RV) Waveform
- Normal Value: _______ mmHg
- Catheter in the RV may cause:
- 15-25/0-8
- ventricular ectopy
Pulmonary Artery (PA) Waveform
- Normal Value _______/_______ mmHg
- Dicrotic notch represents ________ closure
- PA _______ pressure approximates PA wedge pressure which approximates ________ pressure (in absence of lung or MV disease)
- 15-25/8-15
- Pulmonary Valve
- diastolic; LV filling
Right Heart Insertion Sequence of PA cath
Effects of Respiration on Waveforms
General Principles and Definitions
Cardiac Output (CO)
Equation:
Amount of blood that flows out of the ventricle per unit time
CO = Stroke Volume (SV) x Heart Rate (HR)
General Principles and Definitions
Stroke Volume (SV)
formula:
volume pumped per heartbeat
SV = EDV - ESV
Fick’s formula to compute CO
Factors that Affect Stroke Volume
- Preload
- Contractility (inotropic)
- Wall motion abnormalities
- Afterload
- Valvular dysfuction
- Ejection Fraction
Factors that Affect Stroke Volume
- Starling’s law of the heart: bility of the heart to change its________ and therefore _____ in response to changes in venous return (_______stays constant)
- Changes in ventricular preload leads to changes in SV
- Ventricular Preload is ______ at beginning of systole
- EDV is directly related to the degree of ______ of the myocardial sarcomeres
- force of contraction; stroke volume; HR
3 - EDV
4 - stretch
Factors that Affect Stroke Volume
- Ejection Fraction (EF)
Ratio of SV to the end-diastolic volume (EDV)
* EF = (SV/EDV) x 100
* Normal about 55-67%
Stroke Volume
A. Normal SV
B. Normal EDV, ↑ Contraction(EPI)
C. ↑EDV, normal contraction (Starling’s law of the heart)
D. ↑EDV, ↑contraction(EPI)
Determinants of Systolic Function
● Preload: amount of blood in LV before contraction
● Afterload: arterial resistance to emptying
● Inotropy: contractility of LV myocardium
● Systolic Function: CO is determined by preload, afterload, inotropy, HR and rhythm
● Diastolic Function: LA function, LA relaxation, LV compliance, mitral valve, PV blood flow
Afterload equated with:
- Either ________ to ejection or ________ during systole.
Ventricular wall tension during systole:
* Pressure the ventricle must overcome to reduce its cavity.
- The larger the ventricular radius, the ________ wall tension required to develop the same ventricular pressure
- Increases in wall thickness ______ ventricular wall tension
- Arterial impedance; Ventricular wall tension
- Greater; reduces
Laplace’s Law
- Ventricular wall tension
Wall tension (T) = PxR/2h
P: intracavity pressure
R: radius of the chamber
h: thickness of the chamber wall
Wall tension is the pressure the ventricle needs to overcome to reduce its _________
cavity volume
Afterload
- Resistance the blood in the ventricle must overcome to force the valves open and eject contents to circulation
- Inversely related to ______ or _______.
- stroke volume or CO
Afterload:
- Factors that increase afterload:
- Factors that decrease afterload:
- High BP/Systemic resistance
- Aortic stenosis
- MI/Cardiomyopathy
- Decreased volume,
- End stage cirrhosis
- Vasodilators
Afterload
Afterload of the RV
Indirectly assessed as Pulmonary Vascular Resistance (PVR)
Normal PVR: ____-_____
Afterload of the LV
Indirectly assessed as Systemic Vascular Resistance (SVR)
Normal SVR:
- 100-200 dynes
- 800-1200 dynes
LV Afterload Usually Equated to SVR
Systemic Vascular Resistance
formula and range
_________ can be used as an approximation in the absence of:
* Chronic changes in size, shape, or thickness of the ventricular wall
* Absent acute changes in SVR
SVR = 80 x MAP-CVP/CO
Normal SVR = 800 – 1200 dyn-/cm-5
Systemic BP
RV Afterload Mainly Dependent on PVR
Peripheral Vascular Resistance (PVR)
formula:
PCWP is usually substituted for _____
Normal PVR = ______
________ is more sensitive to changes in afterload because of its thin wall.
- PVR = 80 x PAP-LAP/CO
- LAP
- 100-200 dyn-s/cm-5
- RV
Factors Affecting Ventricular Preload (EDV) (9):
- Venous return (most important to ventricular filling)
- Blood volume
- Distribution of Blood volume (alters small venous pressure gradient favoring blood return to the heart)
- Posture (position during surgery)
- Intrathoracic pressure (PPV or thoracotomy)
- Pericardial pressure (Pericardial disease)
- Venous tone
- Rhythm (issues with atrial contraction)
- Heart rate
Determinants of Ventricular Filling
- __________ is the most important factor
- In the absence of significant pulmonary or RV dysfunction, venous return is the major determinant of LV preload
- EDV of both ventricles should be ______ in a normal situation
- ______ can be used as an index of RV and LV preload in normal adults
- ______ or _______ commonly use to estimate preload
- Remember that because the two ventricles function in a series, their outputs are normally equal.
- Venous return
- similar
- CVP
- LVEDP or PCWP
Factors that Affect Heart Rate
- Chronotropic Event
-
Baroreceptors:
Carotid sinus reflex
Aortic reflex -
Other reflexes that influence heart rate:
Anxiety, fear, and anger
Grief
Exercise
Changes in body temperature
Rate Pressure Product (RPP)
The RPP is an indicator of the oxygen requirements of the heart.
Intraoperative tachycardia can cause myocardial ischemia by increasing myocardial oxygen demand.
Controlling the heart rate significantly reduces the risk of perioperative myocardial events.
RPP =
(ideal is = or <______)
RPP = SBP x HR
12,000
Mitral Stenosis
- Normally: _______ cm2 opening
- Stenosis < __cm2
* ____-____ = Mild
* ____-____ = Mod.
* ______ = Severe.
3- Anesthetic Goals:
4- PCWP Waveform:
5- Pressure-Volume Loop:
6- Avoid:
1: 4-6
2: < 2
- 1.5-2 - Mild
- 1 - 1.5 - Mod.
- <1 - Severe
3- * Maintain SR and avoid ↑ HR.
* Avoid hypo/hypervolemia
4- * Prominent a Waves
5- ↓ LVEDP; ↓ SV
6-
* Ketamine
* SPA/Epidurals
* Ephedrine
Mitral Regurgitation
< ___% regurg.= No signs/symptoms
___-___% = Mod. S/S
>_____% = SevereS/S
______ course, then ______ downhill.
LA _________ and pulm. congestion.
Anesthetic Goals:
PCWP Waveform:
Pressure-Volume Loop:
< 30% regurg.= No signs/symptoms
30-60% = Mod. S/S
>60% = SevereS/S
- Gradual; rapid
- overload
Anesthetic Goals:
** Fast and Full*
* Maintain Preload
* ↓ SVR (NTG, NTP)
* ↓ Volatile; ↑ opioid
* avoid hypoxia, hypercapnia.
* IABP, ↑contractility.
- v waves
- ↑ LVEDV and LVESV
Aortic Stenosis
- Gradual Stenosing secondary to:
- **________ LVH
- Normally: ___-____ cm2
___-____ = Mild S/S
____-____ = Severe/Critical -
Symptoms:
* DOE
* Angina
* Orthostatic Syncope. - Hemodynamic Effects of Hypertrophy:
- Anesthetic Goals:
- PCWP:
- Arterial:
- congenital, rheumatic, or degenerative disease
- Concentric
- Normally: 2.5-3.5 cm2
0.7 - 0.9 = Mild S/S
0.5 - 0.7 = Severe/Critical -
Symptoms:
* DOE
* Angina
* Orthostatic Syncope. -
Hemodynamic Effects of Hypertrophy:
* CO cannot ↑ with activity
* ↓ Perfusion of Coronary Arteries
* ↑ O2 demand -
Anesthetic Goals:
* Maintain HR 50-70
* Maintain contractility.
* Maintain Preload (Avoid NTG and
NTP)
* Opioids over agents.
* Avoid hypotension
-
PCWP:
* Prominent V and A waves -
Arterial:
* Absent Dicrotic Notch and slower anacrotic notch.
Aortic Regurgitation
- Just like Mitral Regurgitation, could be acute or chronic. Can be asympt. For 20 yrs., but once symptomatic, _____ yrs. Progression.
- As long as <_____% SV; No S/S
- Can lead to _______ LVH R/T constant LV systolic and diastolic __________.
- _______ is a late and ominous sign
- Anesthesia Goals:
-
PV Loop:
acute vs chronic: -
Regurgitated Volume Depends on:
* HR (slow = ↑ Regurg due to more time)
* Aortic Pressure ( higher DAP =
↑ regurg).
- PCWP:
- Arterial:
- 5
- 40%
- Eccentric; volume overload
- Angina
-
Anesthesia Goals:
* ↓ Afterload
* Keep HR normal
* Adequate Preload, but watch for CHF.
* Forane + Vasodilator
* SPA/Epidurals Okay.
* Keep DBP, HR ↓ - ↑ LVEDV and LVESV
- Acute: LVEDP is high; Chronic: LVEDP
is only slightly ↑ r/t congestion and
absorption.
- Prominent v wave
- Rapid Rise, high systolic peak, low diastolic pressure.
