ch. 27: disorders of cardiac function, heart failure, and circulatory shock -

what makes up the systemic circulation that delivers oxygen-rich blood to the myocardium?

the coronary arteries

what does the L coronary artery divide into?

• the left anterior descending or inter ventricular artery

• left circumflex artery

what does the R coronary artery divide into?

• right marginal artery

• posterior inter ventricular artery

what is coronary artery disease (CAD)?

atherosclerotic plaques have built up in the coronary arteries —> a narrowed lumen —> reduced blood flow to heart muscle

does coronary artery disease (CAD) have an immediate onset

not necessarily, can remain silent for years until blood is significantly reduced

what are possible manifestations of CAD?

• angina attacks

• myocardial infarction

• arrhythmias

• heart failure

• sudden death

what are 2 catergories of CAD?

• chronic ischemic heart disease

• acute coronary syndrome

what are manifestations of chronic ischemic heart disease (CIHD)?

• stable angina

• variant angina

• silent myocardial ischemia

what are manifestations of acute coronary syndrome?

• more severe

• periods of no ST-segment elevation, causing:

  • unstable angina

  • non-ST-segment AMI (acute myocardial infarction)

• ST-segment elevation can lead to ST-segment elevation, causing:

  • Q-wave AMI

  • non-ST-segment AMI (acute myocardial infarction)

when does chronic ischemic heart disease (CIHD) occur?

when there is a deficit of oxygen supply to meet myocardial needs

what is a classic symptom of CIHD?

• angina

  • recurrent episodes of substernal chest pain

  • triggered by emotional or physical stress

how is CIHD classified?

by the kind of angina occurring

what is stable angina?

angina triggered by physical exertion or emotional stress (when O2 demand increases)

what is variant angina?

cyclical spasms in coronary arteries without an increased workload

• pain occurs at rest, often in early morning or at night

what is unstable angina?

• attacks last longer than in stable angina

• less responsive to medication

• prolonged pain at rest may precede acute coronary syndrome

what is silent myocardial ischemia?

• reduced blood flow & oxygen supply to the heart, without noticeable symptoms

• occurs with no pain

where does angina frequently occur?

• chest

• upper abdomen

• back

• beck

• jack

• left shoulder & arm

what does screening for CIHD do?

hopefully identifies asymptomatic stages to reduce risk of complications

what does a stress test monitor?

heart activity & coronary perfusion during exercise

how do you treat an angina attack?

• rest, stopping the activity

• sublingual nitroglycerin

  • dilates coronary arteries —> improves blood flow to myocardium

what causes acute coronary syndrome?

sudden, severe reduction in blood flow to myocardium because of severe narrowing or complete blockage

what is the most common cause of acute coronary syndrome?

atherosclerosis with a plaque rupture

• thrombus at site of ruptured plaque —> blockage

what are manifestations of acute coronary syndrome?

• chest pain at rest

• chest pain is not relieved by vasodilators

• substernal, crushing, radiating, pressure, burning pain in chest

• sudden SoB

what is ST elevation associated with?

• complete arterial blockage

• requires immediate surgery

how does ischemia affect an ECG?

inadequate blood supply alters electrical activity of myocardial cell

what should you assess in an ECG?

the ST segment

• when the ventricles are fully depolarized and contracting to eject blood

• any ECG changes in this segment indicate high probability of MI

what does ST-segment elevation (STEMI) indicate?

likely that a coronary thrombus occluding artery

what do abnormal Q waves indicate?

no depolarizing current conducting from necrotic tissue

what are ECG changes that indicate intermediate or low probability of MI?

• an NSTEMI

• T-wave inversion

what does an NSTEMI indicate?

• lack of ST segment elevation

• clot only partly occludes coronary artery

what does a T-wave inversion indicate?

repolarization of ventricle altered because of myocardial ischemia or MI

how do you treat a STEMI?

• medical emergency to prevent irreversible damage

• percutaneous coronary intervention (PCI)

  • balloon angioplasty to widen arteries

  • stent placement to keep artery open

• thrombolytics

  • dissolve blood clots

• anticoagulants

how do you treat a NSTEMI?

• pharm treatment to reduce myocardial workload

  • beta blockers

• anticoagulants

  • heparin

• monitor ECG & check serum markers

• angioplasty if not stable

what defines a myocardial infarction?

• evidence of myocardial necrosis caused by acute myocardial ischemia

what is the time limit in which irreversible damage and necrosis can occur with a severe coronary artery occlusion?

within 20-40 mins

what are cardiac markers of myocardial infarction?

blood levels of cardiac troponin increase

why is troponin I a preferred cardiac market?

• highly sensitive & specific

• may rise within 3-6 hours after symptom onset

when does myoglobin rise after a myocardial injury is sustained?

• within 2 hours

• not specific to heart though, also in skeleton muscle

when does creatine kinase-MB rise after a myocardial injury is sustained?

6-8 hours afterwards

what are complications of MI?

• sudden death

• cardiogenic shock

• cardiac tamponade

• thromboembolism

• ventricular aneurysm

  • bulging of weakened ventricular wall

what is cardiac tamponade?

a rupture of necrotic heart tissue with blood accumulation in the pericardium

what is the cardiac cycle?

the events occurring in one complete contraction and relaxation of the heart

define cardiac output (CO):

amount of blood pumped by one ventricle in one minute

what’s the average CO for an adult?

5 L/min

define stroke volume (SV):

amount of blood ejected by one ventricle during each contraction

what’s the average SV for an adult?

70 mL

define preload:

the initial stretching of cardiac muscle inside the ventricles at the end of diastole, just before systole

• increased preload = increased SV

define afterload:

resistance the ventricles must overcome to eject blood during contraction

• determined by arterial pressure & peripheral vascular resistance

  • increased afterload —> decreases SV

what is an ejection fraction (EF)?

percentage of blood that is pumped by the L ventricle with each heart beat/contraction

what is cardiac reserve?

the ability to increase CO in order to meet body’s increased demands during physical activity or stress

what is heart failure (HR)?

clinical condition in which heart cannot pump our sufficient blood to meet metabolic needs for O2 and nutrients

• usually complication of another cardiopulmonary condition

what happens when heart cannot maintain pumping capability during heart failure?

• CO or SV decreases

• less blood reaches organs

• mild acidosis develops

• backup and congestion in the affected side of heart since output is less than inflow

what are the 2 ways heart failure is classified?

• functional problem

  • systolic or diastolic

• side of heart affected

  • left or right

what is systolic heart failure?

heart has difficulty contracting & ejecting blood because of weakness and dilation of a ventricle

what is diastolic heart failure?

heart cannot relax & fill with blood because of stiffness or hypertrophy of a ventricle

what is left-sided heart failure?

left ventricle cannot pump blood effectively into systemic circulation

what is right-sided heart failure?

right ventricle cannot pump blood effectively into pulmonary circulation

describe the pathophysiology of left-sided heart failure:

left ventricle weakens, cannot empty —> decreased CO to body —> decreased renal blood flow, activates RAAS system —> blood backs up in the pulmonary vein —> high pressure in pulmonary capillaries —> pulmonary congestion or edema

describe the pathophysiology of right-sided heart failure:

right ventricle weakens & cannot empty —> decreased CO to body —> decreased renal blood flow, activates RAAS system —> blood backs up into systemic circulation (in the vena cava) —> increased venous pressure —> edema in legs, liver, and abdominal organs —> neck vein distention & cerebral edema

define the forward effects of HF:

• the consequences of reduced blood flow from the heart to the body’s tissues

  • similar in left and right sided HF

what are the forward effects of HF?

• reduced oxygen supply

  • cells receive insufficient oxygen to meet their metabolic needs

    • dyspnea

    • shortness of breath

• impaired cellular function

  • reduced oxygen availability decreases cellular energy production

    • fatigue

    • weakness

define compensatory mechanisms?

events activated to maintain BP and blood flow in the event of HF

what are compensatory mechanisms of HF?

• tachycardia

  • trying to maintain systemic blood flow

  • heart muscle begins working much harder, increasing its own oxygen demand

    • more oxygen is delivered during diastole, which is now shortened, so the heart ends up starving itself of oxygen

• RAAS activation

  • due to decreased kidney perfusion

  • triggers cellular stress, inflammation, and cell death

  • stiffens heart walls, impairs relaxation, and dilates chambers

what are backup effects of left-sided heart failure?

• pulmonary congestion

  • because blood backs up in pulmonary circulation

what are clinical manifestations of backup effects of left-sided heart failure?

• dyspnea

• orthopnea

• apnea

• lung crackles

• cough

  • pink, frothy sputum (severe cases)

what are backup effects of right-sided heart failure?

• edema

  • blood backs up in systemic circulation, increasing hydrostatic pressure, and forcing fluid into tissues

what are clinical manifestations of backup effects of right-sided heart failure?

• dependent edema in feet, ankles

• jugular venous distention

• hepatomegaly

• splenomegaly

• ascites

what causes left-sided HF?

• infarction of left ventricle

• aortic valve stenosis

• hypertension

• hyperthyroidism

what causes right-sided HF?

• infarction of right ventricle

• pulmonary valve stenosis

• pulmonary disease

what are basic effects of left-sided HF?

• pulmonary congestion

• decreased CO

what are basic effects of right-sided HF?

• systemic congestion

• edema of legs & abdomen

• decreased CO

what are forward effects of left-sided HF?

• fatigue

• weakness

• dyspnea

• exercise intolerance

• cold intolerance

what are compensations effects of left-sided HF?

• tachycardia

• pallor

• secondary polycythemia

• daytime oliguria (low urine output)

what are compensations effects of right-sided HF?

• same as with the L side

  • tachycardia

  • pallor

  • secondary polycythemia

  • daytime oliguria (low urine output)

what are forward effects of left-sided HF?

• same as with L side

  • fatigue

  • weakness

  • dyspnea

  • exercise intolerance

  • cold intolerance

what are congenital heart diseases?

structural defects of the heart that develop during the first 8 weeks of embryonic development

what are valvular congenital heart defects?

abnormality in 1 or more of heart’s 4 valves, disrupting normal blood flow

what are septal congenital heart defects?

defect in septum

what are blood vessel congenital heart defects?

abnormality in large arteries

what are cyanotic congenital heart defects?

cyanosis caused by structural defect that reduces O2 in blood

what are acyanotic congenital heart defects?

heart problems present at birth that do not interfere with the amount of O2 in the blood or cause cyanosis

what are common manifestations of congenital heart disease (CHD)?

• pallow

• cyanosis

• tachycardia

• heart murmurs

what is the risk of leaving a child with CHD untreated?

child can develop heart failure

what are commonly affected valves in valvular heart defects?

aortic & mitral

what are the classifications of valvular defects?

• stenosis

• valvular incompetence

• valve prolapsa

what is stenosis? what does this cause, and what causes the murmur?

• narrowing

• cause: harder for blood to flow through

• murmur: blood forced throw narrow opening = whooshing sound

nutshell: less blood flows through, but there is no backflow

what is valvular incompetence? what does this cause, and what causes the murmur?

• regurgitation

• cause: valve leaks when it should be closed

• murmur: abnormal heart sound caused by blood leaking backward through the valve

nutshell: blood flows freely forward, but blood regurgitates backwards through the leaky valve

what is valve prolapse?

floppy valve

• one or more of the leaflets bulge backward into the preceding chamber

what are the structural defects in tetralogy of fallot?

a R —> L shunt congenital heart condition

what are the hemodynamic alterations in tetralogy of fallot?

• shunt bypasses pulmonary circulation —> cyanosis

• pressure in heart changes —> alters blood flow

• right heart —> lungs, but less blood traveling here —> deoxygenated blood goes to the left heart —> deoxygenated blood goes to the body —> back to the right heart

what are the 4 structural abnormalities in tetralogy of fallot?

• pulmonary stenosis

  • narrowed pulmonary valve

• ventricular septal defect (VSD)

  • hole in the ventricular septum

• dextroposition of the aorta

  • aorta positioned over the VSD

• right ventricular hypertrophy

  • thickened wall of right ventricle because of increased workload

define pericarditis:

inflammation of pericardium, the double layered membrane surrounding the heart

what is pericarditis usually a result of?

secondary to another condition or injury

• open heart surgery

• MI

• rheumatic fever

• SLE

• cancer

what are signs and symptoms of pericarditis?

• distended neck veins

• faint heart sounds

  • fluid surrounding heart muffles sounds

• cardiac tamponade

  • pressure around heart limits ability to fill with blood

describe the pathogenesis of pericarditis:

fluid around heart compresses heart wall —> heart cannot expand to fill —> blood backs up into systemic circulation —> decreased blood flow to lungs —> decreased output to body

define chronic pericarditis:

long-term inflammation of pericardium

describe pathologic changes associated with chronic pericarditis:

long-term inflammation of pericardium —> formation of adhesions in the pericardial cavity —> adhesions restrict heart’s movement —> reduced CO

what are symptoms of chronic pericarditis?

• symptoms associated with systemic venous congestion & decreased CO

  • SoB

  • edema

  • ascites

what is rheumatic fever?

an acute systemic inflammatory condition from an abnormal immune reaction after an untreated infection of group A beta-hemolytic streptococcus

within what age group is rheumatic fever most common?

5-15 y/o