Cardiovascular Function and Diseases

Question 1

Heart wall (inner to outer)

Answer 1

1. Endocardium
2. Myocardium
3. Epicardium (or visceral pericardium)
4. Pericardial cavity
5. Parietal pericardium

Question 2

Endocardium

Answer 2

Innermost layer

Question 3

Myocardium

Answer 3

Thickest layer of cardiac muscle

Cardiac myocytes (muscle cells) provide contractile force to propel blood

Question 4

Epicardium

Answer 4

Inner layer of the pericardium that lies against the heart surface

Also called visceral pericardium

Question 5

Parietal pericardium

Answer 5

Outer layer of the pericardium that is in contact with lungs and the structures in the chest cavity

Question 6

Pericardial cavity

Answer 6

Space between the visceral and parietal pericardium layers

Contains pericardial fluid (approx. 20 ml)

Functions:

1. Prevents displacement of heart during movement
2. Protects heart from infection/inflammation from lungs and other surrounding tissue
3. Contains receptors that can control HR and BP

Question 7

Heart chambers

Answer 7

RA
RV
LA
LV

Atria are smaller and thin-walled; “storage units” and passageways to the ventricles

Ventricles are larger and thick-walled; pumping chambers

Question 8

Atrioventricular valves (AV)

Answer 8

In-between each atria and ventricle:

1. Right AV valve: tricuspid valve (TV)
2. Left AV valve: mitral valve (MV)

Function as a unit to simultaneously allow blood flow from atria into ventricle, and prevent back flow into atria from ventricle when the ventricle contracts

Question 9

Semilunar valve (SV)

Answer 9

In-between RV and pulmonary artery, and LV and aorta

Open to allow blood to flow from ventricles into greater vessels, and close to prevent back flow into ventricles

Question 10

Coronary arteries

Answer 10

Supply myocardium and other heart structures with oxygenated blood

Originate from the aorta, and divide into smaller RCA and LCA branches

Question 11

Coronary veins

Answer 11

Coronary sinus: empty deoxygenated blood from heart into the RA

Question 12

Cardiac cycle

Answer 12

One heartbeat accounts for one contraction (systole) and one relaxation (diastole)

Systole: contraction (blood leaves the ventricles)

Diastole: relaxation (ventricles fill)

Question 13

Cardiac conduction

Answer 13

1. SA node (“pacemaker” of the heart), located at junction of RA and SVC, generates action potential (AP; 60-100/min)
2. Atria contract
3. AP travels through myocardium to the atrioventricular (AV) node where they pass to the ventricles
4. Bundle of His, located in the interventricular septum, divides into right and left bundles which conduct impulses to the ventricular apex
5. Purkinje fibers are the end branches of the bundles
6. Ventricles contract

Question 14

Myocardial AP

Answer 14

Depolarization: electrical activation of muscle cells

Repolarization: deactivation of muscle cells

Caused by movement of ions (Na2+, Ca+, K+, Cl-) across the cardiac cell membrane that results in a voltage difference (membrane potential)

Question 15

AP phases

Answer 15

Phase 0: depolarization (rapid Na+ entry into cell) (+30 mV)

Phase 1: early repolarization (slow Ca2+ entry into cell)

Phase 2: plateau; continued repolarization (slow Na+ and Ca2+ entry into cell)

Phase 3: late repolarization (K+ moves OUT of cell)

Phase 4: return to resting membrane potential (-70 mV)

Question 16

PQRST EKG wave

Answer 16

P-wave: atrial depolarization

QRS complex: ventricular depolarization and atrial repolarization

T-wave: ventricular repolarization

Question 17

Myocytes (cardiac cells)

Answer 17

Characteristics:
1. Intercalated disks with gap junctions allow electrical impulses to spread quickly from cell to cell

2. More mitochondria due to increased ATP need
3. Increased T-tubules (invagination of muscle membrane) allow faster access to Na+ and K+; conduct impulse to sarcoplasmic reticulum (smooth ER within myocytes) that store Ca2+

Question 18

Atherosclerosis

Answer 18

Chronic inflammatory condition characterized as thickening and hardening of vessels

Characteristics:

1. Endothelial (blood vessel lining) dysfunction
2. Plaque development/narrowing, and/or instability

Consequences (vascular events): MI, stroke, renal artery disease, aneurysm, PAD, CAD

Question 19

Development of atherosclerosis

Answer 19

1. Chronic endothelial injury
2. Immune response adheres to injury
3. Inflammatory response
4. LDL cholesterol penetrates vessel wall and becomes trapped
5. Macrophages with lipids inside accumulate and form a “fatty streak” that release inflammatory cytokines
6. Cytokines stimulate vessel smooth muscle growth
7. Plaque forms over the fatty streak
8. Plaque can calcify and obstruct blood flow, OR rupture (a “complicated plaque”)
9. Plaque rupture exposes vessel underneath, and thrombus forms rapidly, which can obstruct the vessel (angina, infarction)

Question 20

Lipids

Answer 20

Necessary for life (cell membranes, hormone development, bile production)

Types of lipids:
1. Chylomicrons: consist mostly of triglycerides; transport dietary fat from intestine to liver and peripheral cells

2. Triglyceride: major form of lipid; used for energy
3. Very Low Density Lipoproteins (VLDL): triglycerides and protein
4. LDL (“Bad”): cholesterol and protein; delivers cholesterol from liver to cells (cell membranes, steroid hormones)
5. HDL (“Good”): phospholipid and protein; returns excess cholesterol from cells/artery walls to liver to be converted to bile salts

Question 21

Risk of CAD (r/t dyslipidemia)

Answer 21

Linked to:
1. High triglycerides, VLDL, and LDL

2. Low HDL

Question 22

HTN

Answer 22

Consistent, sustained elevation of BP >130 mmHg systolic OR >80 mmHg diastolic

Increases risk of atherosclerotic disease and MI

Question 23

BP classification

Answer 23

Normal: <120/<80
Elevated: 120-129/<80
HTN Stage 1: 130-139/80-89
HTN Stage 2: >140/>90

Goal for BP in pts with diabetes and/or renal disease is <130/80 (below HTN stage 1)

Question 24

Primary HTN (95% of cases)

Answer 24

HTN that is NOT related to another disorder

Risks: FHX, age, gender, ethnicity, high dietary sodium, glucose intolerance, tobacco, obesity, heavy alcohol consumption, low dietary intake of Ca2+, K+, and Mg2+

Question 25

Sympathetic Nervous System (SNS) and HTN

Answer 25

Normally, the SNS promotes maintenance of BP and tissue perfusion SNS over-activity in pts with HTN can result in excess production and secretion of (1) catecholamines (epinephrine or norepinephrine) OR (2) insulin Catecholamines increase HR, BP, RR, muscle strength, and mental alertness Insulin increases sodium and water reabsorption (thus increases BP, ECF)

Question 26

RAAS and HTN

Answer 26

Normally, RAAS promotes maintenance of BP and tissue perfusion RAAS over-activity can result in excess secretion of renin, angiotensin II, and aldosterone which (1) increase blood vessel tone (vasoconstriction) and (2) promote salt and water retention

Question 27

Secondary HTN (5% of cases)

Answer 27

HTN caused by an underlying disease process Caused by: Renal, endocrine and vascular systemic diseases, pregnancy, neurologic disorders, acute stress, medications, and substances Ex.: Renal failure, pheochromocytoma (tumor on adrenal gland that secretes excess catecholamines), arteriosclerosis, and increased ICP (intra-cranial pressure)

Question 28

Other types of HTN

Answer 28

Complicated HTN: damages the walls of systemic blood vessels Malignant HTN: rapidly progressive HTN (crisis) in which the diastolic BP is usually >140 mmHg Orthostatic HYPOtension: decrease in BP >20 mmHg systolic OR >10 mmHg diastolic within 3 minute of moving to a standing position

Question 29

Aneurysm

Answer 29

Localized enlargement/dilation of an artery caused by a weakened artery wall or cardiac chamber Types of aneurysm: 1. True aneurysm: involves distention of all 3 layers of the artery wall 2. False aneurysm: leaking of the vessel forming a clot outside the vessel wall (hematoma)

Question 30

Varicose veins

Answer 30

Vein in which blood has pooled causing distortion, tortuous, and inflammation of the vein (palpable; usually in the saphenous vein) Caused by: Trauma or gradual venous distention, rendering valves incompetent High risk for developing clots

Question 31

Chronic venous insufficiency

Answer 31

Inadequate venous return over a long period as a result of varicose veins and/or valve incompetence S/S: Pain, swelling, skin discoloration (darkening), venous stasis ulcers Increased risk for infection and clotting d/t poor circulation

Question 32

Deep Venous Thrombosis (DVT)

Answer 32

Thrombosis: clot (usually in a large vessel; saphenous vein) Thromboembolism: detached thrombus (that can lead to PE) Veinous flow obstruction leads to increased venous pressure and post-thrombotic syndrome (characterized by pain, swelling, ulceration of affected limb) DVT management depends on clot formation risk and detachment (embolus)

Question 33

DVT risk factors (Virchow's Triad)

Answer 33

1. Venous stasis 2. Venous endothelial damage 3. Hyper-coagulable states (Smoking, liver disease, CA, pregnancy)

Question 34

CAD

Answer 34

Any vascular disorder that narrows or occludes the coronary arteries, resulting in an imbalance between supply of blood and myocardial demand for oxygen and nutrients Reversible myocardial ischemia or irreversible MI may result Most common cause: Atherosclerosis Non-modifiable risk factors: Age, FHX, males, post-menopause women Modifiable risk factors: Dyslipidemia, HTN, smoking, DM and insulin resistance, obesity, diet Nontraditional risk factors: Markers of inflammation and thrombosis (C-reactive protein, troponin I, hypergomocysteinemia), adipokines, infection (microorganisms and periodontal disease), air pollution, coronary artery calcification

Question 35

Acute Coronary Syndrome

Answer 35

Sudden coronary artery obstruction because of thrombosis formation over a ruptured atherosclerotic plaque Ex.: Unstable angina, MI Most common complications: Dysrhythmias, CHF, sudden death

Question 36

Myocardial ischemia

Answer 36

Supply of coronary blood does not meet the demand of the myocardium for oxygen and nutrients S/S: Stable angina: predictable chest pain; caused by (expected by): physical exertion, stress; lasts a short-time, DOES NOT change frequency/worsen over time; relieved by rest/medication Prinzmetal (varient) angina: un-predictable chest pain Silent ischemia: causes no detectable symptoms Angina pectoris: transient substernal chest discomfort

Question 37

Unstable angina

Answer 37

A form of reversible myocardial ischemia; indicates that a plaque has ruptured and MI may occur soon; EMERGENCY Unpredictable; occurs at rest, and may occur with exertion/stress; NOT relieved by rest/medicine Types of unstable angina: 1. Rest angina: occurs at rest; usually prolonged >20 min 2. New-onset angina: new and symptomatic with everyday activities 3. Increasing angina: previously diagnosed, but become more frequent/longer duration, and/or increased with less activity

Question 38

Myocardial Infarction (MI)

Answer 38

Prolonged myocardial ischemia that causes irreversible damage ST segment elevation (STEMI) requires immediate intervention (cathlab); smaller infarction (NSTEMI) suggests additional myocardium is still at risk for recurrent ischemia and MI Two major types of MI: 1. Subendocardial MI: LESS of the myocardium 2. Transmural MI: through the WHOLE wall of the myocardium

Question 39

CV system: Fetus developmental anatomy

Answer 39

Cardiogenesis begins at approx. 3 weeks' gestation 1. Heart arises from the mesenchyme 2. Heart develops as an enlarged blood vessel with a large lumen and muscular wall; midsection grows faster than the ends (week 5) 3. Heart tube elongates and rotates to the right (bulboventricular loop); fetal heart contractions begin (week 7) 4. All fetal heart and vascular systems present (week 8)

Question 40

In-Utero: Fetal shunts

Answer 40

Foramen ovale: opening between the atria Ductus arteriosus: connects pulmonary artery to the aorta (bypasses underdeveloped lungs) Ductus venosus: connects umbilical vein to the IVC (bypass underdeveloped liver)

Question 41

Fetal circulation

Answer 41

1. LA 2. LV 3. Aorta 4. Systemic circulation 5. Umbilical arteries 6. Placenta 7. Umbilical veins 8. Ductus venosus (bypass liver) 9. IVC 10. RA 12. (1) RV; (2) Foramen ovale 13. (1) Pulmonary artery; (2) LA 14. (1) Ductus arteriosus (bypass lungs); (2) LV 15. Aorta

Question 42

Transitional circulation

Answer 42

Circulatory changes take place after birth (gas exchange shifts from placenta to lungs) Fetal shunts close

Question 43

Congenital heart defects

Answer 43

It is the leading cause of death (except for prematurity) in 1st year of life Cause of defect known in only 10% of cases Risk factors: Prenatal (maternal rubella, insulin-dependent diabetes, alcoholism, PKU, hypercalcemia), environmental, and genetic (chromosomal aberrations) Types of defects: 1. Patent ductus arteriosus (PDA): ductus arteriosus fails to close after birth; allows a portion of oxygenated blood to back flow directly from the aorta to the lungs and pulmonary (pulmonary HTN) 2. Atrial septal defect: abnormal opening between the atria after birth 3. Ventricular septal defect (VSD): abnormal opening between the ventricles after birth; common (25-33% of cases) Other defects: Coarctation (congenital narrowing) of the aorta, aortic valve stenosis, pulmonary artery/valve stenosis, and hypoplastic left heart syndrome (underdevelopment)

Question 44

Tetralogy of Fallot

Answer 44

Syndrome represented by four defects: 1. VSD 2. Overriding aorta straddles the VSD (allows deoxygenated blood from RV to enter aorta) 3. Pulmonary stenosis 4. RV hypertrophy S/S: Cyanosis, clubbing, feeding difficulty, and squatting (attempt to force more blood into heart and the narrow area of the pulmonary artery) Hypercyanotic spell ("tet spell") generally occurs with crying and exertion Most causes corrected surgically in early infancy before first year of age (reestablishes reliable pulmonary blood flow)

Question 45

HTN in children

Answer 45

Children often have underlying renal disease or coarctation (congenital narrowing) of the aorta; cause of HTN is almost always found; commonly asymptomatic Clinical manifestation: Systolic and diastolic BP >95th percentile for age and gender on at least 3 occasions Tx: Diet, regular physical activity, avoidance of smoking and drugs