heart disease lectures

4

chambers in the heart

left and right atriums and ventricles

types of chambers in the heart

2 atrioventricular valves (AVs)

prevent backflow of blood into atrium

Tricuspid valve

between RA and RV

Mitral valve

between LA and LV

2 semilunar valves (SLVs)

prevent backflow of blood into ventricles

Pulmonary valve

opening between RV and pulmonary trunk

Aortic valve

opening between LV and aorta

vena cava, pulmonary arteries + veins, coronary arteries

Blood flow through heart and lungs via

Cardiac diagnostic biomarkers

biological molecule whose concentration in the blood changes in response to a specific disease (specific type of tissue damage)

Types of biomarkers

Iso-/enzymes, Structural tissue proteins, Metabolic pathway intermediates, Messenger molecules

Isoenzymes

Made up of several subunits (individual polypeptides encoded by different genes and have different structures (e.g., CK); tissue specific

M subunit

CK isoenzyme subunit characterized by its gene on chromosome 19

B subunit

CK isoenzyme subunit characterized by its gene on chromosome 14

CKBB

higher in brain and GI tract

CKMB

slightly significant at GI tract and cardiac muscle

CKMM

quite significant in cardiac and majorly significant in skeletal muscles

Myocardial infraction (MI)

Cardiac muscle death (ischemia) characterized by coronary artery blockage (atherosclerosis) via lipid plaques AND lack of O2 (reversible if not prolonged)

Troponins (cTn)

Most specific and sensitive biomarker; Markers of choice for patients with acute coronary syndrome (ACS)

80% of patients with acute MI

will have an elevated troponin level within 2-3 hours of emergency department (ED) arrival (elevated up to 2 weeks)

I levels

elevated for up to 10 days

T levels

elevated for up to 2 weeks (not as specific as troponin I due to being elevated alongside skeletal muscle & kidney disorders)

0.01ng/mL or less

normal range of cTn

Myoglobins

also found in muscle; released via tissue damage but sensitive to both cardiac and skeletal muscle damage

absence of myoglobin

usually 2-3 hours after MI

10-95 ng/mL

male myoglobin

10-65 ng/mL

female myoglobin

Creatine kinase (CK)

Found in mitochondria and cytoplasm of skeletal muscle (CKMM), cardiac muscle (CKMB; myocardium), and brain (CKBB); its total amount is nonspecific for cardiac damage

troponins

CKMB less sensitive than _______and rises 4-6 hours after the onset of chest pain and peaks at 12-24 hrs (troponins don’t remain elevated and may subside within 36 hrs; pre-MI)

Creatine

building block for either creatine phosphate (CK combined with ATP) and creatinine

LDH and ALT

rarely used for MI diagnosis; nonspecific (rises later than all previously described methods)

CRP

acute-phase reactant synthesized by the liver in response to cytokines released by tissue damage

Chronic inflammation

this would lead to high levels of CRP (therosclerosis); not specific to the heart

Less than 1.0 mg/L

Low hs-CRP value

1.0 to 3.0 mg/L

Average hs-CRP value

Greater than 3.0 mg/L

High hs-CRP value

Electrocardiogram (ECG)

electrical activity of heart; test MI via disruption

P wave

atrial depolarization and contraction

QRS wave

ventricular depolarization and contraction

T wave

ventricular repolarization and relaxation

Angiogram

test narrow or blocked coronary arteries via contrast dye

Echocardiogram

reflect sound waves (ultrasound), produce heart image and check for it’s ability to pump blood

Chest radiography (X-ray)

useful for cardiomegaly (enlarged heart); size of hearts and if there is fluid surrounding it

Heart attack

reversible artery blockage (blood flow prevention); irreversible damage begins after 30 mins

cardiac arrest

occur suddenly due to electrical malfunction in heart; impaired breathing and fatal if lasts 8 mins without CPR

Congestive heart failure (CFH)

progressive disease; associated with coronary artery disease (elderly)

ANP and BNP

hormones secreted from atria and ventricular cardiomyocytes in response to CHF (produced primarily in response to high cardiac pressure and stretch; regulating BP, electrolyte balance, and fluid volume); counteract vasoconstrictive effects of RASS in increasing BP and retaining salt and water

Plasma BNP

more important predictor of morbidity and mortality in patients with chronic symptomatic heart failure (specimen must be separated from the cells within 4 hours and the plasma (EDTA) refrigerated)

Absence of CHF

plasma BNP levels lower than 100 pg/mL; 100-900< pg/mL indicate increasing disease severity

nonspecific

CFH symptoms are _________ for diagnosis therefore utilize mutliple tests (echoCG = enlarged heart; chest radiograph = fluid around heart; ECG = origin of cardiac events like previously mentioned MI, arrhythmia, valvular disorders, etc.; angiography )

Congenital heart defects

Malformation of the heart that is present at birth (causes are either unknown, but mostly genetic and environmental)

Atrial septal defect (ASD)

congenital heart defect with abnormal opening in the septum that divides the two upper chambers (atria) of the heart

Ventricular septal defect (VSD)

congenital heart defect with abnormal opening in the septum that divides the two lower chambers of the heart (ventricles)

Left-to-right shunting (Acyanotic)

congenital heart defect with left side is at a higher pressure, oxygenated blood from the left atrium or ventricle flows into the right atrium or ventricle and then back to the lungs (RA and RV are not built to withstand increased volumes and pressures; can be surgically repaired)

Tetralogy of Fallot (TOF)

Characterized by the presence of four cardiac abnormalities

Pulmonary stenosis

type of TOF wherein valve is too small, too narrow, and can't open all the way. This causes the right ventricle to pump harder to send blood out to the lungs, leading to LV hypertrophy and right-to-left shunting of blood and early cyanosis

Overriding aorta

type of TOF wherein aorta is in the wrong place above a ventricular septal defect or damaged wall between the left and right ventricles

Transposition of the great arteries (TGA)

when the two main arteries are inverted; pulmonary artery (normally carry deoxygenated blood) is transposed with aorta artery (normally carry oxygenated blood); can be surgically repaired

PDA

after birth, the ductus arteriosus normally closes within two or three days; In premature infants, the opening often takes longer to close (If the connection remains open, it's referred to as a patent ductus arteriosus)

Endocarditis

bacterial infection of the inner layer of the heart

Myocarditis

inflammation of the myocardium, which is the middle layer of the heart wall caused by viruses, bacteria, parasites, and fungi; heart loses its ability to pump efficiently, resulting in MI if severe

Pericarditis

swelling and inflammation of a two-layer membrane surrounding the heart (acute or chronic); Chest pain is the cardinal symptom

blood culture

Endo-myo-peri-carditis diagnosis dealing with inflammation due to infection results to

EBV, CMV, or other antibody titers

Endo-myo-peri-carditis diagnosis dealing with condition due to past infection