Human Anatomy and Physiology - Cardiovascular
What is the second heart sound?
"Dup" Occurs when semilunar valves snap closed at the onset of diastole Higher pitch and shorter duration - use diaphragm
What is the first heart sound?
"Lub" Closing of the mitral and tricuspid valves AV valve produces low pitch that is better heard with the bell There is a longer duration of the first heart sound
What are the 3 cardinal symptoms of aortic stenosis?
1. Angina 2. Syncope 3. Congestive heart failure
What is coronary circulation?
1. Aorta 2. Right coronary artery 3. Left coronary artery - LAD - Circumflex 1. Pulmonary artery 2. Pulmonary vein 3. Vena cava and cardiac veins
What are the causes of paradoxical splitting?
1. Aortic stenosis 2. Left bundle branch block
What happens when the heart gets less blood?
1. Atherosclerosis 2. Vasospasm 3. Thrombosis
What are the neurologic/chemical control?
1. Automaticity 2. Rhythmicity 3. Frequency 4. Pressoreceptors 5. Chemoreceptors
Where does arterial pressure regulation come from?
1. Baroreceptors 2. Atrial/pulmonary artery reflexes 3. Chemoreceptors reflexes 4. Hormonal mechanisms
What 4 factors influence total blood flow?
1. Cardiac excitation 2. Blood volume 3. Vascular compliance 4. Resistance
What are the 4 classes of antiarrhythmics?
1. Class 1 - sodium channel blockers 2. Class 2 - beta blockers 3. Class 3 - K+ channel blockers 4. Class 4 - calcium channel blockers
What is a stroke volume compensatory mechanism?
1. Contractility increased = stroke volume increased 2. Even though end diastolic volume and aortic pressure are unchanged
What are the 2 types of congenital heart disease?
1. Cyanotic 2. Noncyanotic
What is the vasovagal response?
1. Development of inappropriate cardiac slowing and arteriolar dilation 2. Reflects autonomic neural changes - Bradycardia - due to sudden augmentation of the parasympathetic (vagal) activity - Hypotension - from sudden reduction/cessation of sympathetic activity - 2 neural pathways - one originating in the hypothalamus and the other in the heart 3. Reflects autonomic neural changes - Hypothalamic activation may be triggered by emotional stress of pain (central - Stimulation of mechanoreceptors can provoke vasodilation and bradycardia (peripheral) 4. Syncope - Decrease in HR - Decrease in cardiac output - Decrease in perfusion to the brain - Results in syncope
What are the major determinants of myocardial blood flow?
1. Diastolic pressure 2. Vasomotor tone 3. Resistance flow 4. Left ventricular end-diastolic pressure Myocardial blood flow relationship
What does the cardiovascular system consist of?
1. Heart 2. Blood vessels 3. Blood
Heart failure can be caused by an impairment of what?
1. Inability for the heart to fill 2. Inability of heart to pump 3. Not enough blood
What factors is preload enhanced by?
1. Increased circulating blood volume 2. Skeletal muscle contraction that propels blood toward the heart 3. Deep inspiration - decreases intrathoracic pressure and increases abdominal pressure, promoting venous return to the thorax 4. Atrial systole 5. Venoconstriction - promotes blood return
What is the most common causes of edema?
1. Increased venous pressure - most common due to heart failure 2. Generalized edema 3. Inflammation of sepsis 4. Lymphatic blockage
What are common causes of diastolic dysfunction?
1. Ischemic heart disease 2. Ventricular hypertrophy - from longstanding hypertension
What are clinical signs of right sided heart failure?
1. JVD 2. Peripheral edema
Hypertensions is a risk factor associated with what diseases?
1. MI 2. Stroke 3. Renal failure
What are the 2 atrioventricular valves?
1. Mitral 2. Tricuspid
What are the 5 phases of ventricle muscle action potential?
1. Phase 4 - In between APs when the the muscles are at resting membrane potential 2. Phase 0 - initial rapid upstroke - after stimulation an AP is fired 3. Phase 1 - Partial depolarization - drops from +30 to 0 4. Phase 2 - plateau phase - slowing of repolarization 5. Phase 3 - repolarization - back to resting membrane potential
What is stroke volume determined by?
1. Preload 2. Afterload 3. Contractility
What are clinical signs of left sided heart failure?
1. Pulmonary edema 2. SOB
What are the 2 semi-lunar valves?
1. Pulmonic 2. Aortic
What promotes venous return?
1. Rhythmic contraction of skeletal muscles 2. Increased rate and depth of ventilation
What is the electrical pathway?
1. SA node 2. AV node 3. Bundle of His/AV bundle 4. Purkinje fibers
What are the 3 determinants of systolic BP?
1. SV - increased SV increases BP 2. Aortic compliance 3. Diastolic BP
What the the 2 types of valve abnormalities that produce heart murmurs?
1. Stenosis - narrowing of the valve that creates higher velocity flow through constricted opening 2. Insufficency (regurgitation) - a failure of the valve to close completely
When is there a higher oxygen demand?
1. Stress 2. Exercise 3. Cold
What is congestive heart failure classified as? What happens to ejection fraction?
1. Systolic dysfunction - loss of contractility 2. Diastolic dysfunction - impaired compliance The ejection fraction is decreased in pt with systolic dysfunction due to loss of contractility Ejection fraction is maintained in pt with diastolic dysfunction
What is transported throughout the CV system?
1. Things entering from external environment - oxygen - nutrients 2. Materials going between cells - hormones - antibodies 3. Waste products from cells requiring elimination - heat - CO2
The rate of right atrial filling is dependent on what?
1. Total blood volume 2. Venous pressure
What are the sources of ventricular afterload?
1. Vascular resistance 2. Low compliance of ventricle or great vessels
What are the 3 determinants of diastolic BP?
1. Vascular resistance - main determinant 2. Runoff of blood from aorta - back flow of blood 3. Diastolic time interval - more time lapses causes lower HR
What are the 5 phases of mechanical event of the cardiac cycle?
1. Ventricular diastole - relaxation, AV node is open and ventricle fills passively 2. Atrial systole - small amount of additional blood is pumped into the ventricles 3. Isovolumic ventricular contraction - initial contraction increases ventricular pressure closing the AV nodes 4. Ventricular ejection - semilunar valves open when ventricular pressure exceeds pressures in aorta and pulmonary Ventricular ejection (systole) of blood follows 5. Isovolumic relaxation - semilunar valves close when the ventricles relax and pressure in ventricles decreases. AV valve opens
What is a 2 lead system?
1. frontal plane has 6 limb leads 2. transverse plane has 6 pericardial chest leads
What is ejection fraction?
1.Portion of the stroke volume pumped from the left ventricle 2. Referred to as a % Measurement of ventricular performance and describes the fraction of end-diastolic volume ejected from the ventricle during systole
How much more compliant is the venous system over the arterial system?
10-20 times
If autonomic nerves to the heart are cut, what is the spontaneous HR?
100bpm
What is the mean venous pressure?
2mmHg
How many chambers does the heart have? What are the names of these chambers?
4 1. Right atria 2. Right ventricle 3. Left atria 4. Left ventricle
Which of the following post cardiac testing objective findings is expected in a patient's chart who has been recently diagnosed with congestive heart failure?
40% left ventricular ejection fraction
What is the cardiac output?
5L/min amount of blood ejected into aorta each minute
Starting your new position requires you to participate in a community healthy initiative program. Which of the following guidelines most accurately describes the intensity of exercise of a healthy individual?
70% of maximum oxygen consumption
What is the splitting of S2 caused by?
A delayed closure of the pulmonic valve and earlier closure of the aortic valve
What is contractility assessed using?
A pressure volume loop
What is Starling's Law
A relationship between arterial pressure, cardiac output, and total peripheral resistance
What is the all-or-none electrical response of the heart?
A single stimulus for AP in one myocyte results in rapid spread of excitation to all myocytes via gap junctions
Changes in compliance of cardiac muscle affects what?
Ability of the heart to fill with blood
What is the tx for systolic dysfunction aimed at?
Afterload reduction to increase SV
What are negative inotropes?
Agents that decrease contractility
Vascular restriction is achieved by:
Altering blood vessel diameter (vasodilation and vasoconstriction)
What is stroke volume?
Amount of blood ejected from ventricles with each contraction
What is venous return?
Amount of blood flowing from veins into the right atrium per minute - return of blood flow to the right side of the heart
What causes flow murmurs?
Anemia because cardiac output is increased to maintain delivery of O2 to the tissues
The difference in pressure between the ______ and the ______ drives blood flow through systemic circulation
Aorta Large central veins
What does the renal body fluid system influence?
Arterial pressure for long-term pressure control
What is the order of blood flow?
Arteries --> arterioles --> capillaries --> venues --> veins
What is v-fib?
Associated with random chaotic electrical activity CAN BE FATAL IN SHORT PERIOD OF TIME
Where do myocyte connections occur?
At intercalated disks
What is resistance flow most commonly caused by?
Atherosclerosis
What is a 4th heart sound caused by?
Atrial systole Low pitched that may be heard in young children But is associated with CV pathology in adults
What is mean arterial pressure?
Average of systolic and diastolic blood pressure 90-100
What causes unilateral edema?
Blockage of lymphatic drainage
What is tubulance known as in the blood and the heart?
Blood - bruits Heart - murmur
What does laminar flow mean?
Blood flow is smoothly distributed throughout the vessel, with the fastest flow in the center of the lumen and the slowest flow where blood is in contact with the walls of the blood vessel
What is the process through which the blood pumps through the heart and body?
Blood to the body: Right atrium --> right ventricle --> pulmonary circulation via pulmonary artery --> From lungs --> left atrium via pulmonary veins --> left ventricle --> to the rest of the body Blood back to heart: via the superior and inferior vena cava to the atrium
What does cyanosis refer to?
Blue coloration due to the presence of deoxyhemoglobin This means that deoxygenated blood returning to the right side of the heart bypasses the lungs and enters systemic circulation
What happens in right sided heart failure?
Build up of pressure that begins with right ventricle and then moves to right atrium and then back to systemic veins
Arterial pressure =
CO * Total peripheral resistance Any factor that increases either CO or total peripheral resistance will cause an increase in mean arterial pressure
What initiates contractions?
Calcium interacting with troponin
What happens if the myocardium is not well perfused?
Changes in both volume and pressure can occur and have a critical effect on the heart muscle
What are the ECG waveforms produced by?
Changes in voltage differences during the spread of cardiac excitation
What is 2 things is frequency in neurologic/chemical control controlled by?
Controlled by 2 sets of efferent (motor) nerves Sympathetic NS - under the influence of the cardioaccelerator center Parasympathetic NS - under the influence of the cardioinhibitor center
What does a right shift indicate in the Frank-Sterling relation?
Depression of function
On one of your clinical rotations you have the opportunity to participate in exercise stress testing. In the first 8 minutes you decide to terminate the test. You recorded a blood pressure of 165/105 and heart rate of 140 bpm. Assuming the patients resting blood pressure was recorded as 125/85mmHg and pulse as 72 bpm, which finding was most likely responsible for stopping the test?
Diastolic blood pressure
What is blood flow driven by?
Difference in pressure between arteries and veins
Which of the following category of drugs is used in the management of heart failure because it decreases preload?
Diuretics
Your office receives a call from a local physical therapist office regarding a post-surgical patient the twas referred for physical therapy. The physical therapists expresses that she believes the patient is showing signs of a deep vein thrombosis (DVT). Which test or measure would be the most appropriate to confirm the presence of a DVT?
Doppler ultrasonography
Where are murmurs best heard?
Downstream from their origin along the course of the turbulent blood flow
What are positive inotropes?
Drugs that increase contractility Ex - catecholamines, dopamine Using these to treat heart failure increases mortality
What happens in premature atrial beat?
Early P wave
Who is aortic stenosis most common in?
Elder and is caused by calcification of the valve
In the cardiac cycle which happens first, the electrical or mechanical events?
Electrical then mechanical ECG waves - are mechanical
What are arrhythmias often caused by?
Electrolyte abnormalities
What does hypertension cause?
End organ damage
What is the most important determinant of stroke volume?
End-diastolic volume
What is the most common cause of sudden death during an MI?
Fatal arrhythmia (v-fib or v-tachycardia)
The general spread of excitation occurs:
From the inner (endo) myocardium to the outer (epi-) myocardium and from the apex towards the base
What does a left shift indicate in the Frank-Sterling relation?
Greater contractility
Decreases in contractility commonly result in what?
Heart failure
What causes bilateral edema?
Heart failure
What are large arteries?
High pressure reservoirs that store energy during ventricular ejection and release it during diastole to maintain blood flow
What are classic examples of low cardiac output?
Hypovolemic and cardiogenic shock which results in inadequate tissue perfusion Low cardiac output isn't a universal finding in people with shock
What is the most common cause of edema?
Imbalances of hydrostatic and osmotic pressure gradient across the capillary walls
When is S3 normal?
In children or adults after exercise Caused by vibration due to rapid ventricular filling
What is a summation gallop?
In pt with tachycardia, S4 can be fused with S3
When is the murmur the loudest?
In the middle of systole when the pressure gradient across the valve is the greatest
Where is the largest blood volume in the CV system?
In the systemic veins
What happens in septic shock?
Inadequate tissue perfusion with high cardiac output
What is contractility?
Includes other changes in stroke volume that are not attributable to preload or after load The intrinsic vigor of muscle contraction related to the biochemical state of the cell
How do you maintain stoke volume?
Increase contractility - as a means for the body to maintain a normal stroke volume or cardiac output when changes in the ventricle or the aorta
What is left ventricular end-diastolic pressure?
Increases and causes an occlusive force on the capillary beds of the muscle
What is a septum?
It divides the heart into right and left sides
Your pt is concerned about how much stress is placed on her joints when she exercises. She asks about simulating running by exercising in the deep end of a therapeutic pool with a flotation device and stretch cord. Which of the following would serve as the most practical method to determine exercise intensity during the activity?
Level of perceived exertion
What are pressoreceptors?
Located in the carotid sinus and the arch of the aorta
What are chemoreceptors?
Located in the carotid sinus and the arch of the aorta which are sensitive to a lowered oxygen tension of the blood
What is the central pathology in diastolic heart failure?
Low compliance - because left ventricle is thickened and noncompliant Tx - with calcium channel blocker to relax cardiac myocytes during diastole
In pulmonary circulation, what pressure does blood flow at?
Low pressure
What is the most common cause of left-sided heart failure?
MI
Which of the following chart values would provide you with the most accurate measure of the patient's cardiovascular fitness?
Maximum oxygen consumption
What effects does the release of inflammatory cytokines have on shock?
May cause shock 1. Decreased systemic vascular resistance - decreased after load 2. Increased capillary permeability - causing edema and decreased preload 3. Reduced cardiac contractility
What is the primary site of CV control within the CNS?
Medulla oblongata
What is pacemaker potential?
Membrane potential difference in pacemaker cells is -60 There is no stable period of resting membrane potential Most rapid rate of phase 4 (depolarization)
What is the most common valvular lesion caused by rheumatic heart disease?
Mitral stenosis
Which heart valves are closed during ventricular systole to prevent blood from flowing back into the atria?
Mitral valve and tricuspid valve
What is ventricular hypertrophy?
Myocardial thickening Common cause of left axis deviation
What are cardiac muscle cells called?
Myocytes
Can a-fib pts have S4?
NO
Resting myocytes have:
Negative voltage
What is a-fib?
No P waves can be defined QRS - occur at irregular intervals "irregularly irregular" - which can cause stasis to occur
What happens in people with a complete heart block?
No transmission of AV node Likely to have: 1. Bradycardia 2. Reduced cardiac output
What is Kussmaul's sign?
Occurs when there is an increase (instead of decrease) in JVD during inspiration It is a sign of right-sided heart failure
What is the atrioventricular (AV) node?
Only electrical communication between the atria and the ventricles It is characterized very slow electrical conduction
What does the P, QRS complex, and T wave mean?
P - atrial depolarization QRS - ventricular depolarization T - ventricular repolarization
Premature ventricular contraction is missing what wave?
P wave
What is a negative chronotropic effect?
Parasympathetic tone reduces resting HR to 70bpm and parasympathetic stimulation reduces the heart further
What produces a continuous murmur in neonates?
Patent ductus arteriosus --> high incidence in premature infants
What are the 3 layers of the heart in order from outer to inner?
Pericardium --> myocardium --> endocardium
Prior to beginning a health screening on your next patient you decide to perform a chart review. You find that recently this patient has begun taking calcium channel blockers. What is the primary function of this pharmacological agent?
Peripheral vasodilation
What is the mitral valve?
Permits blood flow from left atrium to left ventricle
What is the aortic valve?
Permits blood flow from left ventricle into the aorta
What is the tricuspid valve?
Permits blood flow from right atrium to right ventricle
What is the pulmonic valve?
Permits blood flow from the right ventricle to the pulmonary artery
What is the most common cause of right-sided heart failure?
Pre-existing left sided heart failure
What are venules and veins?
Present little resistance to flow
What happens in left sided heart failure?
Pressure begins to build in left ventricle, then to left atrium --> then to lungs
What is pulmonary hypertension ?
Pressure in pulmonary artery is raised resulting in strain on right ventricle --> can cause right sides heart failure
What is central venous pressure?
Pressure of venous blood in thoracic vena cava and right atrium High venous pressure = low venous return
What does the right side do?
Propel deoxygenated blood to the lungs
What does the left side do?
Propels oxygenated blood to the tissues
What does the term right side refer to?
Pulmonary circulation --> served by the right ventricle
What is coronary ischemia?
Random depolarization leads to the all-or-none electrical response which can lead to fatal arrhythmias
What is paroxysmal atrial tachycardia?
Rapid run of heart beats that begin and end suddenly
What does aortic stenosis lead to?
Reduced stroke volume Decrease in systolic pressure in the aorta
What is Tx for diastolic dysfunction aimed at?
Reducing blood volume and preload and promoting ventricular relaxation
What is myocardial perfusion?
Refers to the amount of blood that flows through the coronary artery to the myocardium It occurs during periods of muscle relaxation or diastole
What do the 2 atria do?
Reservoirs for returning blood to the heart
Amount of flow that occurs depends on:
Resistance
What do the heart valves prevent?
Reverse blood flow
Inspection of the external jugular vein during physical exam provides information about what?
Right atrial pressure
JVD
Right sides heart failure which results in creased right sided heart pressure and JVD
SCENARIOS
SCENARIOS
Where does calcium come from?
Sarcoplasmic reticulum stores
Valve opening the in normal heart is:
Silent
What is BP measured with?
Sphygmomanometer
What is sympathetic innervation?
Stimulation - increase in HR, BP, and contractility Epinephrine and Norepinephrine B-adrenergic receptors
Lack of cerebral flow causes periodic fainting in 3rd degree or complete heart block. What is this fainting called?
Stokes-Adams syndrome Tx - implant pacemarker
Describe cardiac muscle
Striated and has intracellular sarcomere
What is mid systolic click?
Sudden tensing of floppy leaflets of mitral valve
What is a positive chronotropic effect?
Sympathetic nerve stimulation or circulating catecholamines increase HR
What does the term left side refer to?
Systemic circulation --> served by the left ventricle
What is normal BP defined as?
Systolic <120 Diastolic <80 but >60
What is considered hypertension?
Systolic >140 Diastolic > 90
What is considered prehypertension?
Systolic between 120-139 Diastolic between 80-89
What is mitral insufficiency?
Systolic murmur produced by blood flowing backwards through the valve when it is normally closed Produces holosytolic murmur
What is ventricular preload?
The amount of tension on the muscle before it contracts - The end-diastolic volume created by venous return
What is stroke work?
The area within a pressure volume loop
Blood is pumped away from the heart via:
The arteries
What causes the heart sounds we hear?
The closing of the heart valves
What is the stroke volume?
The difference between end-diastolic volume and end-systolic volume
What is pulse pressure?
The difference between systolic and diastolic blood pressure
Diastole refers to what side of the heart?
The left side
What is ventricular after load?
The load against which the muscle exerts its contraction (resistance that the ventricle must work against) The sum of the factors that oppose ejection of the blood during systole
What is diastolic blood pressure?
The minimum pressure recorded in the central arterial system Occurs just before the start of ventricular systole
What is the sinoatrial (SA) node known as? What does it do?
The pacemaker of the heart It is the origin of each normal heart beat
What is systolic blood pressure?
The peak pressure recorded int he central arterial system Occurs during ventricular ejection
What are collateral vessels?
The presence of anastomotic connections that can support circulation - extent is variable in humans
What does the Frank Starling principle describe?
The relationship between stroke volume and end-diastolic volume
Systole refers to what side of the heart?
The right side
What are small muscular arteries and arterioles?
The site of greatest vascular resistance in circulation
Blood is pumped towards the heart via
The veins
What is cardiac output?
The volume of blood pumped by each ventricle per minute Regulated by autonomic nerves and hormones through changes in HR and stroke volume
What do the 2 ventricles do?
They are pumps to propel the blood
What happens to the collateral vessels when myocardial perfusion is compromised by obstructions that affect major vessels?
They enlarge over time and blood flow through them increases
What are capillaries?
Thin walled vessels that provide a large surface area for exchange of gases, nutrients, wastes
What is the primary function of the cardiovascular system?
Transport materials to and from the body
What is Fick's equation?
VO2 = CO * A-VO2 difference Related to central and peripheral factors and its influence on coronary and pulmonary pts
What is parasympathetic innervation?
Vagus nerve Inhibitory (decrease HR and BP) Acetylcholine
What does nitric oxide help to produce?
Vasodilation
Cardiac output must equal what?
Venous return
What does trendelenburg position assist with?
Venous return
AP along T tubules open what channels?
Voltage gated Ca2+ channels and allow calcium into the cell
Changes in compliance of blood vessels walls affects what?
Volume and pressure of the blood
What is vasomotor tone determined by?
Volume of blood passed to the tissue and regulated the artery size
What is paradoxical splitting of S2?
When aortic valve is delayed causing pulmonic valve to occur first
When does systolic dysfunction occur?
When myocardial contraction is week Normally following an MI PT have reduced SV despite normal preload; contractility is reduced; tachycardia is present
When does diastolic dysfunction occur?
When there is low cardiac muscle compliance and poor filling PT have right shift
Looking over your next patient's laboratory values, which of the following statements is correct when describing typical hematocrit and hemoglobin values?
Women have lower hematocrit and lower values than men
How much of the cardiac cycle is systole? How much is diastole?
systole - 1/3 diastole - 2/3