Week 6 Moonbark

Front 1

Similarities b/w cardiac & skeletal muscle?

Back 1

Both have striations. Banding arises from same arrangements of fibrils and filaments.

Front 2

Differences b/w cardiac & skeletal muscle?

Back 2

Cells differ greatly in shape & size. Cardiac muscle is NOT a syncytium. Only cardiac muscle has intercalated disks. Cardiac muscle has no NMJ's.

Front 3

What kind of cells line the endocardium?

Back 3

Simple squamous (entire CV system has this lining)

Front 4

Histologically, what is the difference b/w atrial myocardium and ventricular myocardium?

Back 4

Cells are more densely packed in the ventricular myocardium in order to overcome more resistance

Front 5

What is the size of Purkinje fibers compared to myocytes?

Back 5

Much bigger than myocytes

Front 6

What is the role of intercalated disks?

Back 6

They propagate wave of contraction after the terminus of Purkinje fibers. They transmit the impulse to the bulk of the myocardium.

Front 7

What surrounds myocytes?

Back 7

Collagen

Front 8

What are valves composed of?

Back 8

CT (elastic & collagen) covered with endocardium

Front 9

What are the base of the flap in valves made of?

Back 9

Muscle

Front 10

What occurs in capillaries?

Back 10

Site of gas, nutrient, and waste transfer.

Front 11

What are transient heart sounds?

Back 11

Cardio sounds of short duration, including the normally heart S1 & S2

Front 12

What are heart murmurs?

Back 12

Auditory vibrations of longer duration created when laminar flow is disrupted

Front 13

What is S1 associated with?

Back 13

Closure & tensing of the AV valves at the onset of systole coinciding with the QRS complex on the ECG

Front 14

How does S1 compare to S2?

Back 14

S1 is longer, louder, and lower pitched than S2

Front 15

What are some causes of increased intensity of S1?

Back 15

Thin chest wall, tachycrdia, high sympathetic tone, systemic arterial hypertension, and anemia

Front 16

What can diminish the intensity of S1?

Back 16

Obese animals, pleural or pericardial effusion, diaphragmatic hernia, DCM, hypovolemia, emphysema, or a prolonged P-R interval

Front 17

What can cause splitting of S1?

Back 17

Occasionally auscultated at the apex in large breed dogs or may result from electrical disturbances or mechanical factors (tricuspid or mitral stenosis)

Front 18

What is S2 a/w?

Back 18

Closure of the semilunar valves at the end of systole following the T wave on the ECG

Front 19

Why is an audible split 2nd heart sound sometimes heard on healthy, large breed dogs during inspiration?

Back 19

Due to a longer right ventricular ejection period, which causes the interval b/w pulmonic valve closing and aortic valve closing to be longer

Front 20

What can pathologically cause the splitting of S2?

Back 20

Delayed closure of pulmonic valve is most commonly auscultated in dogs w/pulmonary hypertension as occurs with heartworm dz & right to left patent ductus arteriosus. Also caused by pulmonic stenosis, right bundle branch block, ectopic beats, and ventricular pacing.

Front 21

What can cause premature A2 closure?

Back 21

On occasion can be noted with mitral insufficiency and mitral stenosis

Front 22

When do the 3rd and 4th heart sounds occur? And what do they sound like?

Back 22

Occur during diastole & are not normally audible. When heard, they sound like a gallop.

Front 23

What makes the S3 sound?

Back 23

Rapid ventricular filling generates the S3 sound, also known as S3 gallop, protodiastolic gallop, or ventricular gallop.

Front 24

What causes the S3 sound to be audible?

Back 24

Diastolic volume overloading as in DCM, patent ductus arteriosus, & mitral insufficiency

Front 25

When is the S4 heart?

Back 25

It is presystolic & is heard just b4 S1 & occurs just after the P wave on the ECG. Also called atrial gallop or presystolic gallop.

Front 26

What generates the S4?

Back 26

This low-frequency sound is generated by blood flow into the ventricles during atrial contraction

Front 27

What is an audible S4 in dogs and cats a/w?

Back 27

Usually a/w increased ventricular hypertrophy and stiffness and is sometimes audible in animals with third degree AV block

Front 28

What can create a cardiac murmur?

Back 28

High-velocity flow, flow from narrow restricted area into a larger area, or low blood viscosity

Front 29

What does Reynold's number define?

Back 29

The relationship of cardiac murmurs with flow velocity, vessel size, and blood viscosity

Front 30

How is Reynold's number calculated?

Back 30

(radius)(velocity)(density)/viscosity

Front 31

What are the ways murmurs can be characterized and described?

Back 31

By their timing within the cardiac cycle (systolic, diastolic, portions thereof), location (point of maximum intensity), radiation, intensity (loudness), shape, & frequency (pitch)

Front 32

When do systolic murmurs occur?

Back 32

Between S1 and S2

Front 33

What are protosystolic, mesosystolic, and telesystolic?

Back 33

Early, mid, and late systole

Front 34

When do systolic murmurs occur?

Back 34

After S2

Front 35

What is the difference b/w protodiastolic and presystolic?

Back 35

Protodiastolic occurs in early diastole. Presystolic is when it is audible only at the end of diastole.

Front 36

How is the intensity of a murmur calculated?

Back 36

Velocity x flow = force

Front 37

How are murmurs graded?

Back 37

1-6 with 1 being almost inaudible, 2 soft, 3 moderate, 4 loud but w/o thrill, 5 loud w/thrill, and 6 very loud w/thrill audible w/o stethoscope against skin

Front 38

What are the 3 shapes of heart murmus?

Back 38

Plateau or band-shaped, decrescendo, and crescendo decrescendo

Front 39

How are plateau murmurs?

Back 39

Equal intensity throughout their duration

Front 40

How are decrescendo murmurs?

Back 40

Murmurs that gradually taper off from an initial peak

Front 41

How are crescendo decrescendo murmurs?

Back 41

Diamond-shaped, ejection mumur that builds up to a peak intensity and then taper in intensity

Front 42

What does a mitral insufficiency murmur sound like? And where is it located?

Back 42

Best heard at left apex (mitral valve area) but radiates dorsally & to the right thorax. Characteristic murmur ir plateau & holosystolic. May be protosystolic at first.

Front 43

What causes mitral valve insufficiency?

Back 43

Chronic degenerative valvular dz (endocardiosis), endocarditis, hypertrophic obstructive cardiomyopathy, congenital malformations, & dz's that cause left heart enlargement & dilation of mitral annulus

Front 44

Where is tricuspid insufficiency murmur heard? And what does it sound like?

Back 44

Loudest over right apex (tricuspid valve area). Often difficult to distinguish from radiating mitral insufficiency murmur. Also plateau & holosystolic.

Front 45

What can accompany a tricuspid murmur?

Back 45

Jugular pulsations

Front 46

What can cause tricuspid insufficiency?

Back 46

Congenital malformations of valve, chronic degen. valve dz, or any disorder that causes marked right heart enlargement & valve annulus distention, such as pulmonary hypertension

Front 47

Which of the 2 valve insufficiencies is more common in dogs & cats?

Back 47

Mitral valve insufficiency.
Tricuspid valve endocarditis is extremely rare in dogs & cats.

Front 48

What kind of murmur does aortic stenosis cause? Where is it best heard?

Back 48

Systolic ejection murmur - crescendo-decrescendo. Best heard at left heard base. Sometimes radiates towards the right cranial thorax.

Front 49

What kind of murmur does pulmonic stenosis cause? Where is it best heard?

Back 49

High-frequency crescendo-decrescendo (ejection) holosystolic murmur. Best heard at the left heart base over the pulmonic valve.

Front 50

What is the sound difference b/w pulmonic stenosis and aortic stenosis?

Back 50

Pulmonic stenosis should not radiate along the carotid arteries and aortic stenosis does.

Front 51

What kind of murmurs do ventricular septal defects cause?

Back 51

They produce murmurs that vary tremendously in shape & quality. Most often the murmur is a harsh, mid-to-high frequency holosystolic murmur best heard on the right cranial thorax.

Front 52

What does an atrial septal defect cause?

Back 52

Increased flow across the pulmonic valve as a result of the left to right shunting

Front 53

What causes functional (physiologic) murmurs?

Back 53

Decreased blood viscosity or increased cardiac output. Most often noted in animals w/ anemia, fever, pregnancy, hyperthyroidism, and increased sympathetic tone.

Front 54

How are most functional (physiologic) murmurs classified? And where are they loudest at?

Back 54

Proto to mesosystolic, soft to moderate intensity (grade 1-3) and loudest at the left heart base

Front 55

What kind of murmur does aortic insufficiency usually cause?

Back 55

Decrescendo

Front 56

Which is more common: aortic or pulmonic insufficiency?

Back 56

Aortic insufficiency

Front 57

What is the most common cause of a continuous murmur at the left heart base?

Back 57

Patent ductus arteriosus (PDA)

Front 58

What is atrial fibrillation?

Back 58

Supraventricular tachyarrhythmia

Front 59

Atrial fibrillation has a 50% incidence rate with which heart dz?

Back 59

Dilated cardiomyopathy in dogs

Front 60

What characterizes atrial fibrillation?

Back 60

Characterized by electrical disorganization at the atrium leading to rapid & unorganized atrial depolarizations.

Front 61

When does atrial fibrillation usually develop?

Back 61

When atrial enlargement occurs secondary to an underlying cardio dz

Front 62

How does atrial fibrillation show up on an ECG?

Back 62

No visible P waves - replaced by fine undulations. Tall R waves and deep S waves.

Front 63

The phrenicopericardial ligament is formed by a continuation of which layer of the heart?

Back 63

Fibrous pericardium

Front 64

What is the surface of the heart facing the left thorax called?

Back 64

Auricular surface

Front 65

What is the surface of the heart facing the right thorax called?

Back 65

Atrial surface

Front 66

What are the 4 openings into the sinus venarum of the right atrium?

Back 66

Caudal vena cava, coronary sinus, cranial vena cava, and right atrioventricular orifice

Front 67

What does the foramen ovale do?

Back 67

Allows blood to pass from the right to the left atrium

Front 68

Crista terminalis is at the entrance of the what?

Back 68

Right auricle

Front 69

Where is the trabeculae carnae more numerous?

Back 69

More numerous in right ventricle than in left ventricle

Front 70

What does the ligamentum arteriosum connect?

Back 70

Pulmonary trunk to aorta

Front 71

What is the ligamentum arteriosum called in a fetus?

Back 71

(Patent) ductus arteriosus

Front 72

Which nerve turns around the caudal surface of the ligamentum arteriosum?

Back 72

Recurrent laryngeal nerve

Front 73

Which coronary artery is larger?

Back 73

Left coronary artery is about twice as large as the right

Front 74

What is the coronary sinus?

Back 74

The dilated terminal end of the great cardiac vein

Front 75

Which nerve increases heart rate? And which one decreases heart rate?

Back 75

Sympathetic nerve increases HR. Vagus nerve decreases HR.

Front 76

How is duration of cardiac cycle calculated?

Back 76

It is the reciprocal of HR so just divide 1 by the HR to get sec/beat

Front 77

Atria increases the ventricular pumping effectiveness by ___%

Back 77

20%

Front 78

When atria fail to function, the difference is not noticed unless _____________

Back 78

Exercise-induced

Front 79

How is stroke volume calculated?

Back 79

End diastolic volume - end systolic volume

Front 80

How is ejection fraction calculated?

Back 80

Ejection fraction = stroke volume/end diastolic volume

Front 81

What is pulse pressure? And how is it calculated?

Back 81

Pulse pressure is the amplitude of the pressure pulsations in an artery. It is calculated by subtracting the arterial diastolic pressure from the arterial systolic pressure.

Front 82

How does the pressure compare b/w systemic, aorta, pulmonary artery, and pulmonary veins?

Back 82

Aorta > systemic > pulmonary artery > pulmonary veins

Front 83

How does gravity affect the pressure below and above the heart?

Back 83

Gravity increases the actual pressure that is below the heart, but decreases the actual pressure that's above the heart level.

Front 84

Where does most of the resistance to blood flow happen?

Back 84

Arterioles and capillaries

Front 85

Diff. organ capillary beds are in parallel from each other so that the blood passing thru one will not pass to the other. What is the exception to this?

Back 85

Splanchnic circulation: portal veins carry splanchnic venous blood to the liver

Front 86

Are there more mechanoreceptors or chemoreceptors in the terminal bronchioles and alveoli?

Back 86

More chemoreceptors

Front 87

Where is the cough center located? And which nerve takes the impulses there?

Back 87

Afferent impulses pass via the vagus nerves to the cough center located in the medulla oblongata of the brain

Front 88

What are the 3 anatomical regions a cough can originate from?

Back 88

Upper airway, lower airway, and cardiovascular

Front 89

What is nonproductive (dry) cough usually a/w?

Back 89

Dz of upper airways

Front 90

What does a productive cough suggest?

Back 90

Dz of lower airways

Front 91

What is a "goose honk" cough in toy breeds typical of?

Back 91

Collapsing trachea

Front 92

At what time of day is cough secondary to cardio dz more severe? And why?

Back 92

Evening hours when blood flow is redistributed to the heart, resulting in increased pulmonary venous pressures & interstitial or alveolar edema

Front 93

At what time of day is cough a/w bronchial dz more severe? And why?

Back 93

More severe in the morning b/c pooled bronchial secretions in the terminal airways are moved by increased airflow a/w activity & more forceful breathing.

Front 94

What characterized DCM?

Back 94

Poor myocardial contractility, with or w/o arrhythmias

Front 95

Which breeds of dogs have a genetic predisposition to DCM?

Back 95

Doberman Pinschers, Boxers, and Cocker Spaniels

Front 96

DCM has been a/w deficiency of which nutrient?

Back 96

1-carnitine

Front 97

What is 1-carnitine essential for?

Back 97

Essential component of the mitochondrial membrane transport system for fatty acids, which are the heart's most important energy source

Front 98

What is the major functional defect in DCM?

Back 98

Decreased ventricular contractility (systolic dysfunction)

Front 99

Is DCM chronic or acute?

Back 99

Probably develops slowly but onset of clinical signs may appear acute

Front 100

What kind of arrhythmias commonly develop in association with atrial enlargement?

Back 100

Atrial tachycardia and atrial fibrillation

Front 101

What chambers typically dilate in dogs with DCM?

Back 101

Left atrium and ventricle

Front 102

What are some clinical signs of DCM?

Back 102

Weakness, lethargy, tachypnea or dyspnea, exercise intolerance, cough, anorexia, ascites, and syncope

Front 103

What type of dogs are more likely to have subclinical DCM?

Back 103

Some giant-breed dogs

Front 104

What is a classic heart sound finding in DCM dogs?

Back 104

S3 gallop

Front 105

What ECG abnormality is consistent with left ventricular dilation?

Back 105

Tall QRS complexes

Front 106

What clinical pathology is seen with DCM?

Back 106

Prerenal azotemia, increased liver enzyme, hypoproteinemia, dilutional hyponatremia

Front 107

What is the goal of tx. for DCM?

Back 107

Controlling the signs of CHF, optimizing CO, managing arrhythmias, improving quality of life, and prolonging survival

Front 108

What is the prognosis for DCM?

Back 108

Guarded to poor. Most don't live longer than 3 months after showing signs of heart failure.

Front 109

What drug class is Digoxin in?

Back 109

Cardiac glycoside

Front 110

What is Digoxin's function?

Back 110

Increases myocardial contractility (inotropism) with increased cardiac output, increases diuresis

Front 111

When is Digoxin used?

Back 111

To treat CHF, atrial fibrillation/flutter, supraventricular tachycardias

Front 112

What is digoxin's most probable MOA?

Back 112

Inhibition of membrane-bound Na+/K+ -ATPase pump. When this occurs, Na+ increases in the cell, the exchange of Na+ for Ca2+ is augmented, and calcium influx is increased

Front 113

How can digoxin be toxic?

Back 113

It can directly slow sinus nodal activity due to increased sensitivity to AcH, which can lead to atrial arrhythmias.

Front 114

Which species is more sensitive to digoxin tox.?

Back 114

Cats

Front 115

What are the signs of digotoxin tox.?

Back 115

Cardiac arrhythmia, diarrhea, anorexia, nausea, and vomiting

Front 116

What drug class is Enalapril in?

Back 116

ACE inhibitor

Front 117

What is Enalapril's MOA?

Back 117

Prevents formation of angiotensin II by competing with angiotensin I for the enzyme ACE

Front 118

What does enalapril do?

Back 118

Vasodilator in tx. of heart failure