Cardiology: Block 1 Flashcards
In humans, the formation of a linear heart tube from the primary cardiac crescent occurs between days _ and _ of gestation
21 - 23
Looping of the heart tube and trabecular formation of the ventricle occur at day _ of gestation
26
At __ weeks, the embryonic interventricular communication closes, followed by thickening and remodeling of the ventricular walls in the first trimester
6
By the end of week __, heart development is essentially finished, although the heart continues to enlarge throughout gestation
7
What happens during Phase 0 of myocardial contraction?
Depolarization
Na channels open, + Na flow into membrane causing depolarization
Na depolarizes SA Node
What happens during Phase 1 of myocardial contraction?
Brief repolarization
Peak positive point as Na influx slows and stops
K leaks out
Slow voltage Ca channel opens allowing influx and transition to Phase 2
What happens during Phase 2 of myocardial contraction?
Plateau phase
Influx of Ca balances w/ efflux of K
Ca influx initiates troponin and myosin causing contraction and marks the beginning of a contraction
What happens during Phase 3 of myocardial contraction?
Repolarization
Voltage gated K open and allows efflux from cell causing rapid repolarization and includes completion of contraction and relaxation
What happens during Phase 4 of myocardial contraction?
Resting Potential
K is equal intra/extracellularly and allows for resting potential and is ready to receive action potential
Ca inflow/K outflow occurs during Phases _ -_
These phases represent what event?
1-3
Myocardial contraction= QRS complex
What process returns the myocardium to a resting state?
NKAtp
Sodium Potassium Adenosine Triphosphatase
What four processes can cause/lead to myocardial atrophy?
Bed rest
VAD
CA
Weightlessness
What two processes can cause/lead to physiological hypertrophy?
Exercise
Pregnancy
What three processes can cause/lead to physiological hypertrophy?
HTN
MI
Neurhumoral activation
What happens when persistent stress is present on a pathologic hypertrophied heart?
Heart failure
Ventricular arrhythmia
What are the layers of the pericardium?
Fibrous layer
Parietal / Serous- forms sac
Pericardial cavity
Epicardium / Visceral
How much pericardial fluid is contained within the pericardium and where does it come from?
10-20cc formed by the serous layer
What happens if there is too much pericardial fluid?
Pericardial effusion then inflammation
What direction does the heart sit in the chest?
Rotated Left
Tilted forward
R ventricle- most forward
L atrium- furthest posterior
What borders the heart?
Anterior= sternum and L side of costal cartilage 3-5 Post= descending aorta, esophagus, trachea and posterior lungs Lateral= lungs Superior= ascending aorta and superior vena cava
What is a normal PMI diameter?
1 - 2.5cm
What is Erb’s Point best used for hearing?
Aortic/Pulmonic origin
HCM
Aortic insufficiency
What does it mean if a cardiac pulsation is visible lateral to left MCL?
What does a sustained apex impulse mean?
Cardiac enlargement
LVH
On a lateral x-ray, what forms the anterior border?
What primarily forms the posterior border?
Superior- pulmonary trunk
Inferior- right ventricle
Left ventricle, inferior vena cava
Characteristics of S1
Closure of M/T valves (vetricular contraction)
Timed w/ pulse in carotid artery and onset of systole
Heard at 5ICS and critical for maintaining pressure
Hypovolemia induced regurg heard here
Characteristics of S2
Closure of A/P valves
Corresponds w/ onset of diastole- 2/3 and most important part of cycle
Define Physiologic Splitting
Inspiration delayed closing of pulmonic valve preceded by aortic valve closing from the decrease in intrathoracic pressure
Characteristics of S3
Dull/low pitched signaling the filling of ventricles after S2 during diastole and associated w/ lower leg swelling
Most of time= pathologic
Usually caused by: CHF, mitral/tricuspid insufficiency
What is a pathologic finding in S3 called?
Ventricular gallop from volume overload
S1 S2 S3
Slosh ing in
Characteristics of S4
When atria contract late in diastole
Caused by HTN
What is called an Atrial Gallop?
Stiff ventricle noise heard during S4 from pressure overload
a STIFF wall
S4 S1 S2
Right atria received deoxygenated blood from what structures?
Sup/Inf Vena cava
Coronary sinus
Define Atrial Kick
When both atria contract act the end of diastole and correlates w/ S4
What structure in the right ventricle houses/carries the right bundle branch?
Moderator band
How much thicker is the left ventricle than the right?
What else is different about the left ventricle?
3x thicker
Only 2 papillary chordae, more of a sheet of fibers
AV valves open during ?, close during ? and correspond with ?
Diastole
Systole
S1 and pulse in carotid artery
What are the two leaflets of the mitral valve called?
The mitral area is AKA ?
What are the three leaflets of the tricuspid valve called?
Anteromedial/Posterolateral
Apical/Apex
Anterior, Medial, Posterolateral
What causes the semilunar valves to close and in correspondence with ?
Open during systole, close during diastole from backwards pressure
S2
Aortic + pulmonic closing= DUB
What are the 3 cusps of the aortic valve?
What are the 3 cusps of the pulmonic valve?
Right, Left, Non-Coronary cusp
Anterior, Right, Left
When do the papillary move and in what direction?
Pull leaflets down and together at onset of isovolumtetric ventricular contraction to prevent regurgitation
Tears or ischemia of papillary muscles cause regurgitation of ? valve and is often heard during?
Mitral
MI
Where are the ostia that feed the coronary arteries?
When are they supplied w/ blood?
Behind L and R coronary cusps
Fill during diastole
What parts of the heart does the RCA supply blood?
Inf/Post wall of L ventricle R atrium R ventricle Posterior 1/3 of septum SA/AV node
What does the posterior descending artery supply?
Parts of septum
What does the LAD supply blood to?
Anterior 2/3 of septum
Bundle branches
Anterior left ventricle
What does the LCX supply blood to?
SA node (25% of PTs)
Lat/Post L ventricle
L atrium
PDA in 10% of PTs
What is the sequence of events during depolarization and PQRST?
SA node Interatrial/nodal path AV node Junction/His bundle R/BB Ant/Post facicles Purkinje fibers Ventricle
Autonomic nervous system regulates cardiac output through regulation of what 3 things?
SA node pacemaker rate
Myocardial contractility
Vascular smooth muscle tone
(HR, impulse speed, contraction force)
NS that influences the cardiac cycle emerge from what part of the spine and innervate ? structures through ? types of receptors?
T1-5
Meet at cardiac plexus near aorta arch
Innervate through Beta-1 receptors
SA Node, Atria, AV node, ventricles
How does the parasympathetic NS slow the HR/force?
Dorsal motor nucleus to vagus nerve to the SA node, Atria, AV node and Ventricles
What is the equation for CO?
CO= SV x HR
SV- volume ejected w/ each contraction
HR- number of beats/min
Define Preload
Load that stretches heart muscle prior to contraction (ventricle wall tension at end of diastole)
What are the 4 components of preload?
Total volume
Distribution of blood
Atrial contraction
Compliance
How is CO measured?
Ventricle end diastolic volume
Ventricular end diastolic pressure
Directly measured during left heart catheterization
Estimated during right heart catheterization through pulmonary capillary wedge pressure
Define Afterload
What two factors determine it?
Force that the left ventricle has to pump against
Aortic pressure- mean BP
Volume of ventricular cavity and thickness of ventricular wall
What factors influence aortic pressure?
Define Law of LaPlace
Peripheral vascular pressure
Blood volume
Afterload increases, SV and CO decrease
What 3 mechanisms contribute to the regulation of HR?
Autonomic NS
Bainbridge reflex response to atrial stretch
Thoracic pressure changes during respiration of venous return
What 5 physiological things can affect the heart?
Hypoxia Hypercapnea Ischemia/Infarct Acidosis ETOH
What are the Hs and Ts?
Hypovolemia Hypoxia H+ excess Hypoglycemia Hyperkalemia Hypothermia
Tension Pneumo
Tamponade
Toxin
Thrombosis
Narrow QRS’ is a ? problem
Wide QRS’ is a ? problem
Mechanical/RV
Metabolic/LV