Patho week 6

What coronary artery is most often involved in myocardial infarction and which area of the heart does it supply blood to?

left anterior descending artery supplies the left ventricle

What artery is most commonly involved in MI?

left anterior descending artery

Layers of the heart: very thin, three layered membrane that lines the interior heart and covers the valves

endocardium

Layers of the heart: heart’s muscular layer that contracts, and it is controlled by the autonomic nervous system.

myocardium

Layers of the heart: outermost layer, covers the heart and great vessels and folds over to form the double-walled pericardium which has two layers off visceral and parietal membrane. Between the layers is serous fluid which acts as a lubricant to minimize the friction as the heart contracts and relaxes.

epicardium including pericardium

Electrical currents caused by the movement of positive and negative ions in and out of the cardiac cell membrane

action potentials

Stage 0 of action potential: AP rises in voltage and causes ________ when ______ enters the cell

depolarization, sodium

Stage 1 of action potential: AP reaches a _____ point and slightly ________ in voltage

maximal, decreases

Stage 2 of action potential: long ______ when _______ enters the cell

plateau, calcium

Stage 3 of action potential: rapid ______ when ______ exits

repolarization, potassium

Action potential: Returns to baseline at the resting membrane potential

stage 4

A recording of the electrical activity of the heart that can be measured from certain points on the body. Electrodes can be placed on the skin, and electrical current will project a pattern on a graph depicting the phases of resting potential, depolarization, plateau, and repolarization of the heart.

ECG

P wave represents

SA node and atrial depolarization

QRS represents

ventricular depolarization

T wave represents

ventricular repolarization

Squeezing pain in the chest that occurs when there is lack of blood flow to the myocardium

angina pectoris

Chronic chest pain that the patient has experience in the past and feels similar to past episodes→ The patients has a prescribed mediation for episodes of stable angina and self-medicates for treatment

Stable angina

* Chest pain that is occurring for the first time by a patient, a sudden pain in the chest that is caused by myocardial ischemia.
* New or changing chest pain caused by ischemia

unstable angina

Emergency protocols for unstable angina or MI:

Morphine, Oxygen, Nitroglycerin, Anti-coagulants

Non-ST segment elevation myocardial infarction

* MI is subendocardial and not completely through the heart wall

NSTEMI

ST-segment elevation myocardial infarction

* MI indicates that the infarction is completely through the heart wall
* More severe
* tombstones

STEMI

Most common cause of myocardial ischemia

coronary thrombosis

Causes of myocardial ischemia

* A coronary artery can be blocked by a thrombus (blood clot) that obstructs blood flow to the heart muscle, called a coronary thrombosis
* A coronary thrombosis is a consequence of endothelial injury and platelet aggregation
* If the coronary artery diameter is blocked by 50% to 70 %, an inadequate amount of blood flows past the blockage and ischemia results

coronary thrombosis

Causes of myocardial ischemia

* Another more common cause of myocardial ischemia is accumulation of hardened _______ ______ in a coronary artery 
* A piece of calcified plaque often breaks off, embolizes (travels) downstream, and lodges in a small diameter arteriole
* After lodging in the arteriole, the piece of plaque obstructs blood flow to the distal myocardial tissue

arteriosclerotic plaque

Causes of myocardial ischemia

* A third and less common way that myocardial ischemia can occur is by ____ ____ ______
* Prinzmetal or variant angina is caused by a ____ ____ ______
* The vascular spasm obstructs blood flow through the coronary artery, creating ischemia in the surrounding myocardial tissue
* When the artery relaxes, circulation is returned to the myocardium

coronary artery vasospasm

Causes of myocardial ischemia

* The least common pathophysiological process that can cause angina is related to _______
* In ______, the respiratory and circulatory systems are working properly, but there are not enough RBCs or hemoglobin to carry the oxygen to the heart
* The blood itself has a deficit of oxygen

anemia

* Patients report retrosternal chest discomfort and use terms such as pressure, choking, squeezing, or heaviness on the chest to describe the sensation.
* Can be a crushing sensation felt on the left side of the chest radiating to the left shoulder down the left arm
* Alternatively, cardiac pain can radiate to the jaw, back, neck, right arm, or epigastric
* The individual may become pale, dyspneic, and diaphoretic region

classic cardiac chest pain

Levine’s sign is an indicator of:

classic cardiac chest pain

Symptoms referred to as an anginal equivalent may occur instead of classic angina symptoms

* Often occur in women with symptoms of:
* episodic dyspnea
* Dizziness
* Lightheadedness
* pain of the jaw, epigastric region, or back in response to exertion or stress

anginal equivalent

Three factors that affect the severity of damage caused by an MI:

* ________ of occlusion in the coronary artery
* Length of _______ that the coronary artery has been occluded
* Heart’s ________ of collateral circulation

location, time, availability

How often is a cardiac troponin test normally ordered?

8-12 hours for 1-2 days after I

What do the levels of the cardiac troponin indicate?

indicated extent of myocardial cell death

Major cause of death because of MI

delay in care, you have 30 min

What is a PVC

premature ventricular contraction

When does a PVC occur?

ectopic pacemaker initiates a contraction

* Several PVCs in a row lead to _______ _____where the ventricle is beating _______ without waiting for the completion of each action potential. This can lead to _______ ____, where the heart is beating so rapidly that the ventricle is actually quivering and ___ ejecting any blood.
* The lack of a ______ _____ causes the ___ ___ to fire and a rapid repetitive sequence of VT occurs causing the ventricles to quiver and go into VF. Blood is not effectively being pumped and ________ occur

ventricular tachycardia, independently, ventricular fibrillation, refractory period, AV node, tombstones

An inflammatory disease of the myocardium (muscle layer of the heart) that can range from a mild disorder to a lethal condition

* Inflammation with degeneration and necrosis of cardiac myocytes. 
* Conduction disruption is common.

myocarditis

What is the most common cause of myocarditis?

viruses

When the pericardium undergoes inflammation, and fluid accumulates in the pericardial space

* The fluid is called a pericardial effusion and it surround the hearts

pericarditis

Complication of pericarditis when the fluid accumulates to high levels of 200mL or greater, it can compress the heart, which causes a _____ _______

* This causes the heart chambers to become restricted by the surrounding pericardial fluid so they cannot stretch and fill with blood

Cardiac Tamponade

Common cause of infectious endocarditis:

staph aureus

Important sign of infectious endocarditis

new heart murmurs

Treatment of infectious endocarditis

IV antibiotics for 6 weeks

* Risk factors 
* Prosthetic valves, pacemakers, intravascular devices, IV drug usage
* Pneumonia, pyelonephritis, dental procedures can be a source of microorganisms
* Vegetation develops on the valve
* Vegetation fragments can break off and enter bloodstream (septic emboli)
* Acute or subacute infection
* Diagnosis based on labs and echocardiographic findings (Duke Criteria)
* 3 blood cultures drawn 12 hours apart is the preferred method

infectious endocarditis

MI Classification:

MI occurring spontaneously due to atherosclerotic plaque rupture and thrombotic obstruction of a coronary artery

Type 1

MI Classification

occurring due to lack of oxygen availability for the cardiac muscle, leading to ischemia and infarction

Type 2

MI Classification

resulting in death without biomarkers

Type 3

MI Classification

MI due to stent insertion

Type 4

MI Classification

MI due to CABG

Type 5

Arterial Wall

* The inner lining of endothelial cells
* Damage may lead to arteriosclerosis and atherosclerosis

tunica intima

Arterial Wall

* Smooth muscle
* Regulates blood flow
* vasoconstriction (Alpha-adrenergic nerve fibers)
* Vasodilation (beta-adrenergic nerve fibers)
* Calcium: vasoconstriction
* Calcium channel blockers: vessel relaxation

tunica media

Arterial wall

* outer covering

tunica externa (adventitia)

Substances released by the endothelium:

* responsible for vessel dilation

nitric oxide

Substances released by the endothelium:

* responsible for vessel constriction

endothelin

Substances released by the endothelium:

* responsible for angiogenesis

VEGF

Substances released by the endothelium:

* responsible for diuresis

C-type natriuretic peptide

Substances released by the endothelium:

* responsible for clot prevention

prostacyclin

Substances released by the endothelium:

* responsible for clot formation

thromboxane A2

Systole

contraction

diastole

relaxation

Role of ________

* Immediate changes in blood pressure
* Short-term regulation of BP changes
* Example: lying down to standing

baroreceptors

When BP is too high, the baroreceptors:

* activate ___
* ______ heart rate
* ______ contractility
* decrease _________

PNS, decrease, vasoconstriction

When BP is too low, the baroreceptors:

* activate ___
* ______ heart rate
* ______ contractility
* increase _________

SNS, increase, vasoconstriction

Normal BP

less than 120/ less than 80

elevated BP

120-129/ less than 80

Stage 1 Hypertension

130-139/80-89

Stage 2 Hypertension

140 or higher/ 90 or higher

Hypertensive crisis

higher than 180/higher than 20

Risk factors for _________ include:

* Age
* African American ethnicity
* Obesity
* Family history
* Diabetes mellitus
* Tobacco use
* Stress
* Excessive alcohol intake
* Hypersensitivity to angiotensin II
* High renin secretor

hypertension

Ideal environment for a blood pressure:

* Seated for __ minutes
* No caffeine, exercise, smoking within prior ___ minutes
* 2 measurements: use average
* HTN: 2 _______ measurements of elevated BP on separate days
* Ambulatory BP monitoring may be used

5, 30, separate

Creates a high shearing force against all arterial vessel walls, which causes weakening and injury of the endothelium

Hypertension

Effects of HTN on the heart:

* causes left ventricular hypertrophy, which then requires extra coronary artery blood flow because of the increased energy needs of the enlarged muscle. But there is no extra supply of coronary artery blood so the left ventricle is more susceptible to:

ischemia and infarction

Effects of HTN on the eyes:

* can lead to:

blindness

Effects of HTN on kidneys:

* injured renal arteries that lead to renal:

failure

Effects of HTN on brain

* damaged cerebral arteries that lead to

hemorrhagic stroke

Effects of HTN on extremities:

* _______ in the lower limbs

ischemia

Treatments for HTN:

* DASH diet:

dietary approaches to stop hypertension

DASH diet is made up of:

low sodium, low fat, fruit, veg, whole grains

Treatment of HTN also includes:

* _____ reduction
* _____ activity
* smoking ______

stress, physical, cessation

Treatment for HTN:

* diuretics
* renin ______
* ____ inhibitors
* beta-blockers

inhibitors, ACE

Glucose ______ endothelial cells

injures

Atherosclerotic plaque:

* Endothelial ______ occurs
* WBCs are ______ to the injury site
* Macrophages eat LDLs→______ cells
* Foam cells store ______ until they undergo ______ and release lipids into the tunica media layer
* Inflammatory cytokines attract ______
* Fatty streaks form leading to ______
* The arterial wall becomes less ______
* Plaques calcify and are covered with fibrous ______ cap

injury, attracted, foam, cholesterol, apoptosis, fibroblasts, plaques, elastic, platelet

Why does inflammation in the endothelium increase the risk of a blood clot?

* Plaques _____ causes bleeding
* Plaque can break loose and travel to area and _____ blood flow

rupture, obstruct

Bad cholesterol as involved in plaque formation

LDL/low density lipoprotein

Good cholesterol as it helps excrete cholesterol from the body→ reverses cholesterol transport

HDL/high density lipoprotein

Average ASCVD risk patient levels:

* total cholesterol

less than 150

Average ASCVD risk patient levels:

* LDL

less than 70

Average ASCVD risk patient levels:

* HDL

greater than 60

Average ASCVD risk patient levels:

* triglycerides

less than 150

Lifestyle modifications for hyperlipidemia and atherosclerosis:

* Dietary cholesterol less than ____ mg/day
* Limit ______ fats\*
* ______ physical activity

300, saturated, regular

a widely used technique to diagnose coronary arteriosclerosis.

cardiac catheterization

Primary sign of PAD

intermittent claudication

Symptoms of PAD:

pain, pallor, paresthesia, pulse, sensation distal to proximal

ABI: ankle brachial index used to diagnose:

PAD

Weakening of arterial wall causing bulging or dilation

aneurysm

Berry aneurysms, normally silent

* If ruptures-→subarachnoid hemorrhage

cerebral artery hemorrhage

Most common aneurysm

* May compress organs causing nausea and vomiting
* In thin patient, may see pulsatile mass
* Deep palpation should not be performed
* Bruit may be present

aortic aneurysm

Aneurysm are caused by

arteriosclerotic damage

Tear in lining between tunica intima and media of aorta leading to a splitting of layers

* Blood flows between layers


* Can be lethal
* Symptom onset is sudden
* Patient hears ripping or tearing sound
* Pallor, tachycardia, BP presentation may be variable depending on dissection location 
* Signs:
* Bounding pulse, wide pulse pressure, diastolic murmur, and signs of heart failure
* Treatment=surgery

aortic dissection

Inflammation of arterial walls, autoimmune

vasculitis