comple concepts in cardiac function and alterations

what are the circulatory systems

• circulates blood through a network of blood vessels (Arteries, capillaries, and veins)

  • pulmonary system (right heart)

  • systemic system (left heart)

what is the lymphatic system

• complements the circulatory systems function

  • drains ecessive interstitial fluid from tissues

  • returns fluid back into the blood stream

  • routes via internal jugular and subclavian veins

what are arteries

• thick walled structures transporting oygenated blood

  • includes the aorta (largest) and smaller arterioles (embedded in tussue)

  • composed of 3 distinct layers

what are capillaries

• sites of fluid movement and diffusion

  • echange oygen and diffusion

  • remove carbon dioide and metabolic waste

  • gas diffusion

what are veins

• return deoygenated blood to heart

  • formed by merging capillaries into venules

  • venules merge further to form larger vein

  • have valves

what is the job of the heart

• cardiovascular system:

  • deliver oygenated blood to the tissues and return deoygenated blood to heart

• heart mechanics:

  • propels blood from its left side into the aorta and sustemic circulation to provide essential oygen and nutrients to tissues

layers of the heart

• pericardium

  • tough fibrous sac encasing the heart

    • fibrous - outer

    • serous - inner (epicardium)

    • epicardium is further subdivided into the visceral and parietal layers. between these layers is »»»

  • myocardium

    • the thick middle muscular layer that contains the heart muscle

  • endocardium

    • innermost layer lining chambers and covering heart valves

coronary circulation

• arterial origin

  • coronary arteries supply arterial blood directly to the heart muscle

    • originates grom the aorta just above the aortic valve

• right coronary

  • supplies the right side of the heart (RCA)

    • SA node: provides key blood to supply to the sinoatrial node

• left coronary

  • main artery (LCA) bifurcates into 2 key branches

    • LAD: supples the anterior wall of the heart

    • circumfle: circles left to feed the lateral wall

what are cardiac cells

• capable of spontaneously initiating an electrical impulse (automaticity), repsonding to an electrical impulse (ecitability), and propagating these impulses from one cell to another (conductivity)

what is the conduction pathway

• SA node (main pacemaker) starts the heartbeat at 60-100 bpm

• signal spreads across the atria for it to contract

• pauses briefly at the AV node to allow vetricles to fill

• travels through bundle of His, bundle branches, and Purkinje fibers ventricles contract

  • backup pacemakers

    • AV node: 40-60 bpm (slower bradycardia)

    • ventricles: 30-40 bpm (very slow)

electrical activity of the heart: at rest (polarized)

• sodium outside, potassium inside

• inside of cell has a negative charge compared to outside

• a reversal of these charges occurs when the move. this is called»

electrical activity of the heart: depolarization

• soidum moves into the cell, potassium moves out

• cell becomes postiive, leading to contraction

• reverts to polarized state once complete

electrical activity of the heart: repolarization

• ions return to their normal positions

• cell goes backk to its resting state (recovery)

cardiac cycle (heart beat): diastole

• resting and filling

• atria and ventricles are relaed

• ventricles fill with blood

• AV valves are open

• pressure is low in ventricles

cardiac cycle (heart beat): atrial systole

• active filling

• atria contract

• forces remaining blood into the ventricles

• “Atrial kick”

cardiac cycle (heart beat): ventricular systole

• contraction

• ventricles contract

• pumps blood to the lungs and body

• rising pressure in the ventricles closes the AV valves, and forces rhe semilunar valves open

what is cardiac output

• amount of blood pumped by each ventricle in liters per minute (L/min)

• about 4-6 L/min but varies greatly dependinh on the metabolic needs of thr body

• function of the stroke volume and the HR, ,stroke volume is the amount of blood ejected with each heartbeat and includes both the contractility of contractility of the heart (stroke) and the amount of blood (volume). the average resting stroke bolume is about 70 mL

• cardiac output = stroke volume HR

• normal is around 4-7 per min

effect of stroke volume on cardiac output: preload

• how much the heart muscle is stretched when the ventricles fill with blood at the end of diastole

  • more blood in the ventricle > more stretch

  • more stretch > stronger contaction > more blood pumped outcalled frank-staling law of the heart

• preload is decr. by a reduction in the volume of blood returning to the ventricles

• preload is incr. by incr. the return of circulating blood volume to the venticles

• more stretch = more blood u get

• overstretch is a problem

• DIURETICS TO DECR. BLOOD VOLUME!

effect of stroke volume on cardiac output: afterload

• Afterload is the resistance the heart has to push against to pump blood out

• right side of the heart

  • pumps to lungs

  • low resistance > called ppulmonary vascular resistance (PVR)

• left side of heart

  • pumps to the body

  • high resistance > called systemic vascular resistance (SVR)

• contractility

• fluids can incr. blood volume

what is blood pressure

• force on vessel walls

• force eerted by circulating blood on blood vessel walls, measured in mmHg

• systolic pressure (higher number)

  • pressure during ventricular contraction

  • SBP = pressure when heart is contracting

• Diastolic (lower)

  • pressue during ventricular relaation

  • DBP = pressure when heart is relaed

what is cardiac cycle

• sequence of heartbeat events

• complete sequence of electrical and mechanical events in one heartbeat

• systole (contraction phase)

  • heart muscle contracts to pump blood

  • systole = heart contracts

• diastole (relaation phase)

  • heart muscle relaes and fills with blood

  • diastole = heart relaes and fills

• cardiac cycle MAKES bp

what is the lymphatic system

• lymphatic system and the cardiovascular system are closely linked

  • components: lymph, lymph vessels, lymph nodes

• colects interstitial fluid (lymph) and returns it to the cardiovascular system, helping maintain preload and volume

special considerations: aging and cardiovascular health

• as people age, the heart and blood vessels become stiffer and less fleible

  • heart muscle changes > less effective pumping

  • vessels and valves stiffen > reduced blood flow

  • fewer pacemaker cells > higher risk of arrhythmias

  • slower stress response > decreased cardiac output

special considerations: gender and bio. factors - female

• heart: smaller with smaller coronary arteries, blockages happen easier

• phys: females often have higher resting HR, stroke volume, and EF

• CAD timing: occurs ~10 urs later in gemales; estrogen may play a role

• monitoring: both sees diet at a siimilar rates; monitor lipids, BP, weight, and insulin

• normally found postmenopausal

  • losing estrogen causing the protective heart sheath to decr. creating CVD

special considerations: gender and bio. factors - transgender health

• hormone therapy (TW) may lower or not change MI risk

• may incr. risk of VTE (blood clots)

• potential to have venous clots and then causes pulmonary blood clot

what is hypertensive emergency

• acute complication of HTN, defined as a severe incr in BP (commonly >180/120), associated with potentially life threatening target organ damage

  • #1 cause of hypertensice crisis because they stopped taking their BP meds

    • bc htey feel fatigued, lower libido, etc

  • eample: MI, ischemic/hemorrhagic stroke, pulmonary edema

hypertensive emergency: causes

• nonadherence to treatment

• acute kidney failure

• brain hemorrhage or stroke

• eclampsia

• drug misuse

hypertensive emergency: risk factors

• female biologic se

• obesity

• history of CAD or HTN

• high number of prescribed drugs

• treatment nonadherence

management of hypertensive crises: protocol

• goal: you need to lower BP safely and effectively (go by your facility)

• admit to ICU, monitor BP closely, and inititate IV meds immediatly

management of hypertensive crises: arterial line use

• an arterial line is helpful for accurate monitoring but should not delay treatment

• necessary for assessment of target organ damage and precise parenteral administration

management of hypertensive crises: IV meds

• commonly used agents in IV form:

  • enalaprilat and esmolol

  • fenoldopam and hydralazine

  • labetalol and nicardipine

  • hydrochloride

nursing interventions for hypertensive crisis

• nurse observes pt closely for evidence of end organ dysfunction and recognizes that treatment within an hr is necessary to prevent end-organ damage

  • frequent vitals

  • comprehensive neuro check

  • strict I and Os, (look for decr. urine output)

  • review lab work results

  • assess for enal and cardiac compromise

• CBC, BMP, BUN, creatinine, troponin and CK-NB

  • troponin is for when there is damage to heart

what is coronary artery disease

• most common type

• nurses must understand its manifestations, assessments, prevention, and treatment

what is cardiovascular disease

• leading cause of death in the U.S. and globally

  • accounts for > 17.9 million deaths globally

  • epected to incr. to 23.6 million by 2030

what is arthersclerosis

• buildup of lipids (LDL) and fibrous tissue in arterial walls, causing narrowing and reduced blood flow to the myocardium

• repetitious inflammatory response to injury to the arterry wall

• also causes: thickening, hardening, stiffness, and loss of elasticity

artherosclerosis major cardiac disorders caused by

• coronary artery disease (CAD)

• carotid arterry disease

• hypertension

• abdominal aortic aneurysm (AAA)

• peripheral arterial disease (PAD) » most likely have CAD

what does artherosclerosis look like?

• fatty streaks: lipids depposit in intima

• early onset: can start in childhood

• endothelial injury: triggers inflammaiton (smoking, HTN)

• inflammation and clotting: macrophages, platelet attracted

• plaque development: lipids and inflammatory infiltrate narrow flow

• rupture and thrombus: sudden obstruction, major problems

non modifiable risk factors for artherosclerosis

• age: males >45, post menopausal people

• se: higher male risk under 55, equalizes after 55

• ethnicity: incr.. risk in African, meican, native, and asian american populations

• family histoy: first degree relative with premature heart disase

modifiable risk factors for artherosclerosis

• diabetes

• HTN

• smoking

• obesity

• physical inactivity

• high cholesterol

• unhealthy diet

• alcohol use

• and stress

clinical manifestations of atherosclerosis

• progression and symptoms:

  • symptoms and complications depend on arterial narrowing, thrombus formation, and blood flow obstruction to the myocardium

• cartical outcomes

  • MI

  • unstable angine

  • sudden cardiac death

  • stroke

treatment and management of atherosclerosis

• identify and ctonrol RF (HTN, DM)

• pharm therapy (meds)

• diet changes ot heart healthy

• eercise

• lifestyle modifications

coronary artery disease

• definition: CAD occurs when coronary arteries narrow from artherosclerosis, reducing blood flow to the heart

• prevalance: most common heart disease in the U.S., affecting about 1 in 20 adults age 20+

• demographics: men often decelop CAD earlier, womens risk incr. post-menopause

CAD alternative terminolofy

• Coronary heart disease (CHD)

• ischemic heart disease (IHD)

WHat is acute coronary syndrome (ACS)

• sudden dramatic reduction in blood flow

• includes unstable angina, NSTEMI, and STEMI

  • unstable angine (emergency)

    • chest pain occuring at rest, follows a worsening or unpredictable pattern

  • stable angina

    • chest pain occuring with actvity or stress

    • relieved by nitroglycerin

  • MI

    • complete or severe blockage of a coronary artery

    • leads to permenant heart muscle damage

what is angina pectoris

• chest pain or pressure caused by myocardial ischemia, which occurs when heart muscle receives insufficient oygen rich blood

• typically results from artherosclerosis narrowing the coronary arteries, preventing blood flow from meeting incr. demand during eercise, stress, or eertion

• pain may be felt in chest, jaw, shoulder, back, or arm

stable angina

• predictable pain occuring during physical activity o stress

  • short duration

  • releievd by rest

  • relieved by nitroglycerin

unstable angina

• medical emergency

• sudden unpredictable chest pain that can occur even at rest

  • lonoger duration

  • not relieved by rest

  • unpredictablel pattern

  • give 3 nitros, call 911 stat

  • can feel like unstable angina, but can also be something else