Clinical CV Anatomy and Physiology

Lecture 5

What is defined as the relaxation of both atria and ventricles.

diastole

What is defined as the contraction of the atria?

atrial systole

What is defined as the contraction of the ventricles?

ventricular systole

What ensure one way blood flow through the cardiac cycle?

pressure difference in chambers

normal valves

What makes the heartbeat sounds?

sequential closing of 2 sets of valves

What are the atrioventricular valves?

tricuspid and mitral

What are the semilunar valves?

pulmonary and aortic

What are the low pressure components of the heart?

right atrium

right ventricle

pulmonary artery

left atrium

What are the high pressure components of the heart?

left ventricle

aorta

What component is the surrogate marker of blood pressure in the body?

aorta

What is defined as the volume of blood pumped over some unit of time, measured in L/minute?

cardiac output

What is the equation for cardiac output?

heart rate x stroke volume

Stroke volume is determined by what 3 factors?

preload

contractility

afterload

What is the equation for stroke volume?

end diastolic volume (EDV) - end systolic volume (ESV)

What is defined as the stretch of heart muscle fibers at the end of diastole, just before contraction, which reflects ventricular filling and is determined by venous return?

preload

List conditions that can increase preload.

volume retention —> sympathetic tone, RAAS activation, IV fluids

List conditions that can decrease preload.

hypoxia

electrolyte derranegments

hypothermia

hypotension

acidosis

low cortisol/thyroid hormone/glucagon

What is defined as the intrinsic ability of heart muscle to contract independent of preload?

contractility

List conditions that can increase contractility.

sympathetic stimulation

catecholamines

thyroid hormone/glucagon

medications (Dobutamine)

List conditions that can decrease contractility.

heart failure

parasympathetic (rest and digest) stimulation

acetylcholine

hypoxia

hyperkalemia

acidosis

medications

What is defined as the resistance the left ventricle must overcome to eject blood during systole?

afterload

List conditions that can increase afterload.

high blood pressure

aortic stenosis (aortic valve is constricted)

List conditions that can decrease afterload.

low blood pressure

A dog has the following measurements:

• Heart rate is 100mL/minute

• Volume of blood pumped is 4000mL/minute

• End systolic volume (ESV) of 20mLs

What is the cardiac output?

4L/minute —> given in question

A dog has the following measurements:

• Heart rate is 100mL/minute

• Volume of blood pumped is 4000mL/minute

• End systolic volume (ESV) of 20mLs

What is the stroke volume (SV)?

CO = HR x SV

SV = CO/HR = 4000mL / 100bpm = 40mL/beat

A dog has the following measurements:

• Heart rate is 100mL/minute

• Volume of blood pumped is 4000mL/minute

• End systolic volume (ESV) of 20mLs

What is the end diastolic volume (EDV)?

SV + ESV = EDV

40mL + 20mL = 60 mL

A dog has the following measurements:

• Heart rate is 100mL/minute

• Volume of blood pumped is 4000mL/minute

• End systolic volume (ESV) of 20mLs

What is the ejection fraction?

SV / EDV = EF

40 / 60 =0.667 = 66%

What cardiac property is defined as the contractile state of the heart?

inotropy

What cardiac property is defined as the speed of the heart?

chronotropy

What cardiac property is defined as the speed of conduction of an electricle impulse?

dromotropy

What cardiac property is defined as the property relating to the speed of myocardial relaxation?

lusitropy

What concept describes how the heart automatically adjusts its stroke volume in response to changes in venous return (preload)?

Frank-Starling Law

What is the equation for mean arterial pressure?

cardiac output (CO) x systemic vascular resistance (SVR)

List conditions that can increase MAP.

exercise

hypothermia

RAAS activation

anything that increases stroke volume / cardiac output / systemic vascular resistance (vasoconstriction)

List conditions that can decrease MAP.

heart failure

septic shock

anything that decreases stroke voluem / cardiac output / systemic vascular resistance (vasodilation)

What is determined by blood viscosity, vessel length, and vessel radius; primarily altered by arterial vasoconstriction and determines flow distribution?

resistance

What is the volume of blood a vessel can hold at a given pressure; primarily altered by venous capacity and determines volume distribution?

compliance

True or False: Most of the blood volume of the circulation resides in the systemic veins.

True

True or False: Most of the systemic vascular resistance is attributable to the microcirculation, i.e. arterioles.

True

True or False: Generalized vasoconstriction of the arterioles changes TPR; vasoconstriction of the veins doesn’t.

True

True or False: The highest velocity of blood flow occurs in the vicinity of the heart (aorta, pulmonary artery); the lowest velocity of blood flow occurs in the capillaries.

True

True or False: Blood flow in the arteries is highly pulsatile; blood flow in the systemic veins is much less pulsatile.

True

True or False: Pressure in the arteries is highly pulsatile; pressure in the veins is not.

True

What is defined as the amount of oxygen delivered to the tissues over time?

oxygen delivery

O2 delivery = CO x [O2]arterial

What is defined as only the oxygen used by the body?

oxygen consumption

O2 consumption = CO x {[O2]arterial = [O2]venous}

What are the functions of circulation?

perfusion/oxygen delivery

waste removal

maintain blood pressure/volume

Explain RAAS.

activated by reduced renal perfusion, hypotension, or fluid loss

angtiotensinogen made in the liver and renin released by the kidney

renin acts on angiotensinogen to make angiotensin I

angiotensin converting enzyme from the lungs acts on angiotensin I to make angiotensin II

angiotensin II causes vasoconstriction, release of aldosterone, increases thirst, stimulates ADH release, and sympathetic stimulation —> causes myocardial fibrosis and promotes cardiac remodeling from chronic activation

What are the 3 natriuretic peptides with CV significance?

ANP

BNP

CNP

What is the function of natriuretic peptides?

salt and water homeostasis, blood pressure control

Which natriuretic peptide is normally produced in the atria after wall stress and results in vasodilation, natriuresis, and downregulation of RAAS?

ANP

ANP is synthesized as ______ whcih undergoes cleavage of a signal peptide yielding ____.

pre-proANP

pro-ANP

ProANP is stored in atrial myocyte granules and is cleaved by ____ into NT-proANP and active C-terminal ANP which are released into blood in response to atrial stretch and dilation.

atriopeptidase

Which natriuretic peptide is produced more in the ventricles and is released with hypertrophy or wall stress resulting in vasodilation, natriuresis, and downregulation of RAAS?

BNP

What can be used as an indicator of acute atrial distention since it is released from myocardial granules in response to atrial distention, sympathetic stimulation, angiotensin II, and endothelin?

ANP

What neurohormonal system increases activity in CHF via compensatory activation to cause sodium and water retention, vasoconstriction, and increase preload and afterload?

Renin-Angiotensin-Aldosterone-System (RAAS)

What is the comprehensive chart that shows the mechanical, electrical, and pressure events of the cardiac cycle as they occur over time?

Wiggers Diagram

List the 5 phases of the cardiac cycle in order.

atrial systole (atrial contraction)

isovolumetric contraction

ventricular ejection

isovolumetric relaxation

ventricular filling

Which heart sound is caused by the closure of mitral and tricuspid valves?

S1

What heart sound is caused by closure of aortic valve closely followed by the pulmonary valve?

S2

Which heart sounds are considered gallop sounds?

S3 and S4

What heart sound is caused by the diastolic filling of the ventricle?

S3

What heart sound is caused by atrial contraction against a stiff ventricle and coincides with the P wave on ECG?

S4

When do gallop sounds occur?

diastole

What heart sound is msot frequently associated with delayed closure of the pulmonic valve?

splitting of S2

What heart sound occurs during systole, often signaling early chronic degenerative valve disease?

mid-systolic clicks

How can we characterize heart mumurs?

congenital

acquired

physiologic/innocent

location (apical vs basilar, right vs left)

timing (systolic vs diastolic vs continuous)

loundness

What locational term is used if the murmur is loudest ventral to the costchondral junction (AV valve regions/higher on body)?

apical

What locational term is used if the murmur is loudest dorsal to the costchondral junction (aortic and pulmonic valve regions/lower on body)?

basilar

Most cat murmurs occur during which phase?

systole

A physical exam that is focused on a cardiovascular issue is most concerned with what components?

murmur presence

pulses

heart rate

blood pressure

Describe the flow of blood through the heart starting and ending with the lungs.

Lungs —> pulmonary vein —> left atrium —> mitral valve

—> left ventricle —> aortic valve —> aorta —> body —>

vena cava —> right atrium —> tricuspid valve —> right

ventricle —> pulmonary valve —> pulmonary artery —>

lungs

Create a differential diagnoses list for a diastolic murmur at the left apex in the dog.

mitral valve stenosis

Create a differential diagnoses list for a diastolic murmur at the left base in the dog.

aortic insufficiency secondary to aortic stenosis (young)

pulmonary insufficiency secondary to pulmonary hypertension, pulmonary stenosis (young, older)

aortic insufficiency secondary to degenerative valve disease, endocarditis, or aortic stenosis (older)

Create a differential diagnoses list for a diastolic murmur at the right apex in the dog.

tricuspid valve stenosis

Create a differential diagnoses list for a continuous murmur at the left base in the dog.

patent ductus arteriosus

Create a differential diagnoses list for a systolic murmur at the left base in the dog.

pulmonary stenosis

subaortic stenosis

non-pathologic murmur

ventricular septal defect

Create a differential diagnoses list for a systolic murmur at the left apex in the dog.

mitral valve dysplasia

mitral regurgitation secondary to annular dilation

degenerative mitral valve disease

Create a differential diagnoses list for a systolic murmur at the right hemithorax in the dog.

ventricular septal defect

tricuspid valve dysplasia

tricuspid valve regurgitation secondary to normal leak, degenerative disease, or pulmonary hypertension

Create a differential diagnoses list for a systolic murmur at the left apex in the cat.

HCM

mitral valve dysplasia

DLVOTO

Create a differential diagnoses list for a systolic murmur at the left base in the cat.

DRVOTO

pulmonic stenosis

subaortic stenosis

Create a differential diagnoses list for a systolic murmur at the right side in the cat.

ventricular septal defect

tricuspid dysplasia

Create a differential diagnoses list for a systolic murmur at the parasternal/sternal location in the cat.

ventricular septal defect

innocent murmur (kittens)

Create a differential diagnoses list for a systolic murmur that is diffuse in the cat.

innocent murmur

anemia

hyperthyroidism