Cardiac Flashcards
What is the most common cause of ischemic heart disease?
Atherosclerosis of coronary arteries = decreases blood flow to myocardium
What is stable angina?
Chest pain that arises with exertion or emotional stress
What is the underlying cause of stable angina?
Atherosclerosis of coronary arteries w/ >70% stenosis = decreased blood flow is unable to meet metabolic demands of myocardium during exertion
Is stable angina a reversible or irreversible process? What is a hallmark finding in this kind of damage?
- Reversible injury to myocytes (no necrosis)
- Cellular swelling
What is the clinical presentation of stable angina?
Chest pain lasting <20 mins that radiates to left arm or jaw, diaphoresis, and SoB
EKG in a pt w/ stable angina would show what change? Why?
- ST-segment depression
- Subendocardial ischemia = ST-segment depression
What Rx is given to treat stable angina? How does this drug work?
- Nitroglycerin (or just relieved by rest)
- NG can vasodilate both arteries and veins; most importantly is NG’s effect on veins, which would decrease preload and therefore the stress on the heart
What is unstable angina?
Unstable angina is chest pain that occurs @ rest
What is the most common underlying cause of unstable angina?
Rupture of atherosclerotic plaque w/ thrombosis –> incomplete occlusion of a coronary artery
Is unstable angina an irreversible or reversible process?
Reversible injury to myocytes (no necrosis)
What changes would EKG show in a pt w/ unstable angina?
ST-segment depression (due to subendocardial ischemia)
What Rx is used to treat unstable angina?
Nitroglycerin
What is a complication that a patient w/ unstable angina may develop?
Myocardial infarction (pt w/ unstable angina has high risk of progression to MI)
What is Prinzmetal angina? What is it caused by?
- Episodic chest pain (unrelated to exertion)
- Coronary artery vasospasm (causes ischemia to all layers of vessel wall)
Is Prinzmetal angina a reversible or irreversible process?
Reversible injury to myocytes (no necrosis)
What EKG changes would be present in a pt w/ prinzmetal angina? Why?
- ST-segment elevation
- Transmural ischemia causes ST-segment elevation
What Rx’s can be used to treat prinzmetal angina?
- Nitroglycerin or Ca2+ channel blockers (to relieve vasospasms)
Is myocardial infarction a reversible or irreversible process?
Irreversible (necrosis of cardiac myocytes)
What is usually the underlying cause of myocardial infarction?
Rupture of an atherosclerotic plaque w/ thrombosis and complete occlusion of a coronary artery
What are 3 other possible causes for myocardial infarction aside from that involving atherosclerosis?
- Prolonged ( > 20mins) coronary artery vasospasm (e.g. Prinzmetal angina or cocaine use)
- Emboli
- Vasculitis (e.g. Kawasaki disease)
How does myocardial infarction present clinically?
Severe, crushing chest pain ( > 20 mins) that radiates to the left arm or jaw, diaphoresis, dyspnea
What part of the heart is usually affected by myocardial infarction?
- Left ventricle (RV and both atria are usually spared)
What are the 3 most common blood vessels involved in myocardial infarction?
- Left Anterior Descending (most common; 45% of cases); Right coronary artery (2nd most common); Left circumflex artery
Occlusion of the LAD in MI causes infarction in what areas of the heart?
LAD: infarction of ant. wall and ant. IV septum
Occlusion of the right coronary artery leads to infarction of what areas of the heart?
RCA: Post. wall; post. IV septum; papillary muscles of the LV
Occlusion of the LCX in MI causes infarction of what part of the heart?
LCX: Laterall wall of the LV
Where in the heart is necrosis seen in the initial phase of MI? What changes would EKG show?
- Initial phase of MI = subendocardial necrosis (involving <50% of mycardium)
- ST-segment depression
If MI persists, where in the heart is necrosis seen? What changes in the EKG would be seen?
- Transmural necrosis; involving most of the myocardial wall (this is the most common type of infarction)
- ST-segment elevation
What are 2 cardiac enzymes that are elevated in MI? Which is useful to detect reinfarction and why?
- Tropinin I (most sensitive and specific marker for MI; peaks @ 24 hrs and returns to normal 7-10 days later) and CK-MB
- CK-MB is useful for detecting reinfarction that occur days after an initial MI b/c CK-MB levels rise and peak @ 24 hrs and return to normal by 72 hrs
What are the different treatment options for MI? (Hint: limit thrombosis, minimize ischemia, vasodilate, slow HR, decrease LV dilation, open blocked vessels)
- Aspirin and/or heparin - limit thrombosis
- Supplemental O2 - minimize ischemia
Nitrates - vasodilate veins and arteries
B-blocker - slow HR (decreases O2 demand and risk of arrhythmia)
ACE Inhibitor - decrease LV dilation
Fibrinolysis or angioplasty - open blocked vessel
What are 2 complications to be concerned of when openning a blocked vessel?
- Contraction Band Necrosis (Reperfusion of irreversibly-dmg’d cells causes Ca2+ influx –> hypercontraction of myofibrils)
- Return of O2 + inflammatory cells –> free radical generation –> further dmg myocytes (Pt will present w/ rising cardiac enzymes despite opening occluded vessel)
Describe the gross changes, microscopic changes, and complications: < 4hrs from MI
Gross: none
Microscopic: non
Complications: Cardiogenic shock (if large infarct causes heart to stop beating all together), CHF, and arrhythmia
Describe the gross changes, microscopic changes, and complications: 4 - 24 hrs after MI
Gross: dark discoloration
Microscopic changes: coagulative necrosis (pyknosis –> karyorhexis –> karyolysis)
Complications: Arrhythmia (if MI dmgs conducting system)
Describe the gross changes, microscopic changes, and complications: 1 - 3 days after MI
- Gross: yellow pallor
- Microscopic: neutrophil invasion
- Complications: Fibrinous pericarditis (only if transmural infarction had occurred –> inflamm exudate extends out from the epicardium into pericardium)
Describe the gross changes, microscopic changes, and complications: 4 - 7 days after MI
Gross: yellow pallor
Microscopic: Macrophages
Complications: Rupture of ventricle –> cardiac tamponade; Rupture of IV septum –> leads to shunt; Rupture of papillary muscle –> leads to mitral insufficiency
Describe the gross changes, microscopic changes, and complications: 1 - 3 weeks after MI
Gross: red border emerges as granulation tissue enters
Microscopic: Granulation tissue w/ fibroblasts, collagen, and bv’s
Complications: none
Describe the gross changes, microscopic changes, and complications: Months after MI
Gross: white scar
Microscopic: fibrosis
Complications: Aneurysm; mural thrombus; Dressler Syndrome (Autoimmune pericarditis that happens 6-8wks after MI)
What is Dressler Syndrome? When does it occur?
Dressler Syndrome is an autoimmune pericarditis that happens 6-8 wks after MI; transmural infarction + inflamm w/n pericardium –> exposure of pericardial antigens to immune system –> pt can devo Abs agains pericardium
What is sudden cardiac death? What is usually the cause?
- Unexpected death due to cardiac disease; occurs w/o symptoms or <1 hr after symptoms arise
- Usually due to fatal ventricular arrhythmia
What is the most common etiology of sudden cardiac death? What are 3 other less cammon causes of sudden cardiac death?
- acute ischemia (90% of pts have preexisting severe atherosclerosis)
- Other less common causes: mitral valve prolapse; cardiomyopathy; cocaine abuse
What is chronic ischemic heart disease? What complication can this lead to?
- CIHD is poor myocardial fxn due to chronic ischemic dmg (w/ or w/o infarction)
- Progresses to CHF
What is the process by which pulmonary symptoms arise in CHF? What are 4 sypmtoms that can be seen?
- Pumonary congestion due to blood being back up –> leads to pulmonary edema
- Dyspnea, paroxysmal nocturnal dyspnea (due to increased venous return when lying flat; this is dyspnea that happens after lying down for a few hours); orthopnea (dyspnea that occurs after lying down for a few minutes); and crackles (due to edema)
What are “heart-failure” cells? How do they arise?
In Left-sided heart failure, small capillaries in the lungs get congested and may burst –> intraalveolar hemorrhage –> macrophages eat this up and become hemosiderin-laden macrophages = heart-failure cells
How does the RAA system exacerbate left-sided heart failure? What is therefore a mainstay Rx for left-sided heart failure?
- Decreased flow to kidneys –> activation of RAA system –> ANG II constricts arterioles (increase TPR) and facilitates release of Aldosterone (increase fluid retention) = exacerbate CHF
- ACE Inhibitors
What is the most common cause of right-sided heart failure? What are 2 other important causes of right-sided heart failure?
- Most commonly due to left-sided heart failure
- Other important causes:
1. L –> R shunt
2. Cor pulmonale (Chronic lung disease –> hypoxia –> bv in lungs constrict –> RH has to pump against this increased pressure)
What are 3 clinical features of right-sided heart failure due to congestion?
- Jugular vein distension
- Painful hepatosplenomegaly w/ characteristic “nutmeg” liver –> may lead to cardiac cirrhosis (when cirrhosis occurs due to chronic congestion of hepatic vein due to RH failure)
- Dependent pitting edema (due to increased hydrostatic pressure)
What is Eisenmenger syndrome? How does it arise?
- Eisenmenger syndrome is a reversal of a L –> R shunt into a R –> L shunt
- L –> R shunt increases flow through pulm. circulation –> results in pulm hypertrophy and pulm HTN –> increased pulm resistance reverses shunt from L –> R to R –> L
What is the most common congential heart defect? What syndrome is it closely associated with?
- Ventricular Septal Defect (VSD)
- Fetal Alcohol Syndrome
What are 3 clinical symptoms due to a reversal of shunt in Eisenmenger syndrome?
- RV hypertrophy (due to Pulm HTN)
- Polycythemia (due to EPO release from the hypoxemia)
- Clubbing of fingers (due to cyanosis)
What is the treatment of large VSD? What is treatment of small VSD?
- Surgicial closure
- Small defects may close spontaneously
What is the most common form of Atrial Septal Defect?
Ostium secundum (90%)
What syndrome is ostium primum closely assoc with?
Down Syndrome
What kind of shunting is seen in ASD?
L –> R
What is heard on auscultation of ASD? Why does this occur?
- Split S2
- Increased blood in RH delays closure of pulm valve
What is an impt complication that can arise from ASD? Give an example.
- Paradoxical emboli
- DVT embolus usually lodge into pulm circuit and cause PE, but due to ASD, it may escape into systemic circuit into an uncommon area (e.g. brain or distal extremities)
What congenital heart defect is associated w/ congenital rubella?
Patent Ductus Arteriosus (PDA)
What kind of shunt does patent ductus arteriosus cause? Between which 2 vessels?
- L –> R shunt
- Aorta and pulm artery
What is the use of ductus arteriosus in the developing fetus?
During devo, ductus arteriosus shutns blood from pulm artery to aorta in order to bypass the uninflated lungs
What characteristic murmur is heard with PDA at birht?
A continuous “machine-like” murmur can be heard
If Eisenmenger syndrome arises in PDA, what clinical symptoms arise?
Lower extremity cyanosis
Why is cyanosis only seen in lower extremities if Eisenmenger syndrome occurs in PDA?
Ductus arteriosus arises after the proximal major branches of aortic arch (which supplies upper extremities)
What is the treatment for PDA? Why?
- Indomethacin
- Indomethacin decreases PGE; elevated PGE is responsible for keeping PDA open
What are the 4 symptoms of Tetralogy of Fallot?
- Stenosis of RV outflow tract
- RV hypertrophy
- VSD
- Aorta that overrides the VSD
What kind of shunting is seen in Tetralogy of Fallot? What determines the extend of shunting?
- R –> L shunt
- Degree of RV outflow tract stenosis determines extent of shunting
In pts w/ Tetralogy of Fallot, what physical manipulation do they do to reduce cyanotic spells? Why does this alleviate cyanotic spells?
- Patients learn to squat in response to cyanotic spells
- Squatting increases arterial resistance –> decreases R -> L shunting and allows more blood to reach the lungs
What cardiac defect is classically described as having a “boot-shape” on x-ray?
Tetralogy of Fallot
What is transposition of great vessels?
Cardiac defect where pulm artery arises from LV and aorta arises from RV
What cardiac defect is assoc w/ maternal diabetes?
Transposition of great vessels
What are 2 treatments used for Transposition of Great Vessels?
- Surgical creation of shunt (in order to allow blood to mix) is required for survival
- PGE can be administered to maintain a PDA until surgical repair is performed
What changes to heart morphology is seen in Transposition of Great Vessels?
Hypertrophy of RV and Atrophy of LV
What is truncus arteriosus?
Cardiac defect where a single large vessel arises from both ventricles (truncus fails to divide durign devo)
What cardiac defect results in RV hypoplasia due to failure of devo of tricuspid valve?
Tricuspid atresia
What morphological change in heart is seen in tricuspid atresia?
RV hypoplasia
What other cardiac defect is Tricuspid Atresia assoc w/?
ASD
What is coarctation of the aorta? What are the 2 subtypes?
- Narrowing of the aorta
- Subtypes:
1. Infantile form
2. Adult form
What other cardiac defect is the infantile form of Coarctation of the Aorta assoc w/?
Infantile form is assoc w/ a PDA