Chapter 12: Heart Flashcards
What are Lambl excrescences?
-filiform projections on the closure lines of aortic and mitral valves, probably related to fibrosed thrombi
Main mechanisms of cardiac dysfunction
- pump failure
- outflow obstruction
- regurgitation
- rupture of heart or a major vessels
- conduction abnormalities
- shunts
What is the main dysfunction in congestive heart failure?
-the heart is not able to pump at a rate sufficient to keep up with metabolic demand; or does so at the expense of increased filling pressure
What is the Frank-Starling mechanism?
-mechanism to maintain arterial pressure and perfusion by which increased filling volumes dilate the heart, increase functional cross-bridges between sarcomeres, and thereby increase contractility
What happens to hypertrophied myocytes?
- a response to pressure or volume overload or other trophic signals
- increased protein synthesis permitting assembly of more sarcomeres
- increased mitochondrial
- enlarged nuclei
- not accompanied by a sufficient increase in capillary synthesis such that oxygen supply is more tenuous than in the normal heart
- increased metabolic demands make the hypertrophied heart more vulnerable to decompensation
Morphology of pressure overload hypertrophy?
- concentric wall thickening
- due to sarcomeres assembled parallel to the long axes of cells
Morphology of volume overload hypertrophy?
-chamber dilatation due to sarcomeres arranged in series to existing ones
Main causes of left sided heart failure
- ischemic heart disease
- mitral and aortic valvular diseases
- myocardial disease
- hypertension
Consequences of left heart failure
- pulmonary congestion
- stasis of blood in left side of heart
- decreased perfusion of organs leading to their dysfunction
Diastolic failure
- relatively preserved pump function but failure of heart to relax due to stiff ventricle
- heart unable to increase its output in response to increased demand
- can cause flash pulmonary edema
- most common cause: hypertension
Morphologic features of right sided heart failure
-hypertrophy and dilatation of right atrium and ventricle
Most common congenital cardiac malformations
-VSD>ASD>pulmonary stenosis>PDA
What are the main categories of cardiac congenital anomalies
- right to left shunts
- left to right shunts
- obstructions
What are secundum ASDs?
- most common type
- occur near the centre of the atrial septum
- usually not associated with other abnormalities
What are sinus venosus ASDs?
- less common type
- located near opening of SVC
- may be associated with anomalous pulmonary venous return
What causes persistent truncus arteriosus?
Failure of the truncus to separate into the aorta and pulmonary artery resulting in a single artery receiving bilateral blood flow and giving flow to systemic, pulmonary and coronary circulations
-associated with VSD
Which gender more often gets coarctation?
-males, but females with Turner syndrome are at high risk
Four clinical syndromes by which IHD presents
- myocardial infarction
- angina pectoris
- sudden death
- chronic IHD with heart failure
What is the primary cause of IHD syndromes?
-insufficient coronary perfusion for myocardial demand due to chronic, progressive atherosclerotic narrowing of the coronary arteries
What event generally precipitates acute coronary syndromes?
-change from a stable plaque to an unstable plaque through rupture, erosion or hemorrhage
Describe Prinzmetal angina
- caused by coronary spasm
- symptoms unrelated to exercise
- may coexist with coronary atherosclerosis
What are causes of transmural MI in the absence of the usual coronary artery pathology?
- vasospasm (sometimes in connection with cocaine)
- emboli from the left atrium or paradoxical emboli from the right heart
- disorders of small vessels in the heart such as due to vasculitis
What is a subendocardial infarct?
- involves the inner 1/3 of the myocardium
- least perfused area of the myocardium
- possible causes include a thrombus that becomes lysed before causing more damage (in the territory of that thrombus), systemic hypoperfusion
Potential causes of infarct extension
- retrograde propagation of a thrombus
- proximal vasospasm
- impaired contractility rendering flow through stenoses inadequate
- arrhythmia
Gross and microscopic appearance of a reperfused infarct?
Gross: hemorrhagic
Micro: irreversibly injured myocytes contain contraction bands
Complications of acute MI
- arrhythmia
- pericarditis (Dressler syndrome; fibrinohemorrhagic)
- contractile dysfunction (heart failure; cardiogenic shock)
- myocardial rupture (VSD, free wall, papillary muscle rupture)
- RV infarction
- infarct extension
- infarct expansion
- ventricular aneurysm
- papillary muscle dysfunction
- mural thrombus
Microscopic features of chronic IHD
- patchy myocardial fibrosis, sometimes with distinct old infarcts
- subendocardial vacuolar change
- mural thrombi
- myocyte hypertrophy
Non-atherosclerotic causes of sudden cardiac death?
- congenital structural or coronary artery anomalies
- aortic stenosis
- mitral valve prolapse
- dilated/hypertrophic cardiomyopathy
- pulmonary hypertension
- congenital or acquired arrhythmias
- cardiac hypertrophy of any cause (e.g. hypertension)
- drugs of abuse (cocaine, methamphetamine)
- metabolic/catecholamine causes
What electric abnormalities of the heart predispose to sudden cardiac death?
- long QT syndrome
- Brugada syndrome
- short QT syndrome
- Wolff-Parkinson-White
- congenital sick sinus syndrome
- catecholaminergic polymorphic ventricular tachycardia
- isolated cardiac conduction disease
What are channelopathies?
- mostly autosomal dominant mutations in genes for normal channel function
- e.g. genes encoding K, Na or Ca channels, or accessory proteins
- e.g. long QT syndrome
4 main categories of disorders predisposing to cor pulmonale (not including left heart failure)
- primary pulmonary disorders (e.g. fibrosing, COPD, etc)
- pulmonary vascular disorders (e.g. recurrent PE, primary pulmonary HTN)
- chest wall abnormalities (e.g. kyphoscoliosis, obesity/sleep apnea)
- disorders inducing pulmonary arterial vasoconstriction (metabolic acidosis, obstruction of large airways, etc)
Pathologic features of cor pulmonale
- RV hypertrophy, sometimes isolated to the outflow tract or moderator band thickening (connects ventricular septum to anterior RV papillary muscle)
- fibrous thickening of tricuspid valve
- myocytes appear more concentrically arranged compared to their usual more haphazard arranged
- RV dilatation
What is functional valve regurgitation?
-regurgitation resulting from instability of one of its support structures, e.g. ventricular dilatation pulling the valve muscles downwards and causing regurg
Commonest causes of aortic stenosis?
-calcification of normal or bicuspid valves
Commonest cause of aortic regurg?
-dilatation of ascending aorta, usually related to htn and age
Commonest cause of mitral regurg?
-MVP (myxomatous degeneration)
Commonest cause of mitral stenosis?
Rheumatic heart disease (post inflammatory scarring)
Acquired aortic stenosis
- most common valvular disorders
- age related wear-and-tear of normal or bicuspid valves
- may have relation to atherosclerosis but differs in morphology with valves having osteoblastic cells that synthesize bone matrix proteins and deposit calcium salts
Morphology of acquired aortic stenosis
- heaped up calcific masses protruding through outflow tracts into the sinuses of Valsalva, preventing valve opening
- usually does not involve the free edges of the valve cusps
- unlike rheumatic and congenital causes, no commissural fusion is seen
- unlike rheumatic disease, mitral valve is usually normal
- eventually associated with LV hypertrophy, ischemic damage, and heart failure
What is the most frequent cardiovascular anomaly in humans and what is its prevalence?
- bicuspid aortic valve
- 1% prevalence
What is the morphology of a bicuspid aortic valve?
- two cusps, usually of unequal size, with the larger cusp having a midline raphe
- raphe is a major site for calcific deposits
- mitral valve usually normal in these patients
Mitral annular calcification
- calcific deposits around the annulus, most common in elderly women
- usually does not affect valve function but may rarely lead to regurg or stenosis
Mitral valve prolapse
- ballooning of the mitral leaflets, which are enlarged, redundant, thickened and rubbery
- attenuation of the collagenous fibrosa layer with thickening of the spongiosa and deposition of mucoid (myxomatous) material
- secondary changes include fibrous thickening of the valve leaflets where the contact, linear thickening of the LV endocardium where the valves contact it, thrombi and calcifications
Causes of mitral valve prolapse
- unknown in most
- Marfan syndrome
Clinical features of MVP
- most asymptomatic
- mid-systolic click
- complications include: infective endocarditis, mitral regurg, stroke or infarct from embolism of leaflet thrombi, arrhythmia
What is an Aschoff body?
- cardiac lesion in acute rheumatic fever
- T cells, plasma cells and Anitschkow cells (activated macrophages)
- may be present in any layer of the heart (endocardium, myocardium, pericardium = pancarditis)
What acute valvular lesion occurs in rheumatic fever?
-small verrucous deposits along lines of closure, overlying necrotic foci in valves
What are MacCallum plaques?
-subendocardial plaques, most often in left atrium, seen in rheumatic fever caused by regurgitant jets
Mitral valve changes in chronic rheumatic heart disease?
- leaflet thickening
- commissural fusion and shortening
- thickening and fusion of tendinous cords
- mitral valve always involved, with aortic valve in 25% of cases, and occasional involvement of tricuspid and pulmonic valves
What is the pathogenesis of rheumatic fever?
- antibodies against the M protein of group A strep cross-reacts with cardiac proteins
- T cells specific for M protein also react with self-proteins in the heart
- therefore, a combination of antibody and cell-mediated immunity
5 major manifestations of rheumatic fever?
- sydenham chorea
- erythema marginatum
- pancarditis
- migratory polyarthritis
- subcutaneous nodules
Major organisms responsible for endocarditis
- Strep viridans
- Staph aureus (especially IVDU)
- enterococci
- HACEK
- Staph epidermidis (most often in prosthetic valves)
Clinical features in infective endocarditis
- fever
- murmur
- splinter hemorrhages
- Janeway lesions (erythematous non-tender, palms and soles)
- Osler nodes (subcutaneous in pulp of digits)
- Roth spots (retinal hemorrhages)
What are the Duke criteria?
- criteria for diagnosing infective endocarditis
- clinical and pathologic criteria
Nonbacterial thrombotic endocarditis
- small sterile vegetations along lines of closure
- non-infective/invasive, but may embolize
- often in debilitated patients (cancer, sepsis, aka marantic endocarditis), and may be associated with DVT, PE, etc
- may be associated with endocardial trauma
What part of the heart is most often involved by carcinoid heart disease?
-right heart valves and endocardium
What are the gross features of carcinoid heart disease?
- plaque like fibrous thickening in right heart
- microscopically, smooth muscle, collagen and mucopolysaccharides
Most common clinical manifestation of carcinoid heart disease?
Tricuspid insufficiency>Pulmonic insufficiency
Complications of artificial valves
- thromboembolic complications (main problem with mechanical valves)
- infective endocarditis
- structural deterioration (bioprosthetics»mechanical)
What is the fundamental dysfunction in each type of cardiomyopathy
Dilated: contractile dysfunction
Restrictive and hypertrophic: diastolic dysfunction
Pathologic features of hypertrophic cardiomyopathy
- disproportionate septal hypertrophy (free wall:septum=1:3) with septal thickening most prominent in the subaortic region
- banana shaped ventricle
- endocardial thickening/mural plaque formation of outflow tract with anterior mitral valve leaflet thickening
Histologic features of hypertrophic cardiomyopathy
- myocyte disarray
- increased myocyte diameter (40 microns)
- interstitial fibrosis
Genetic defects in hypertrophic cardiomyopathy
- genes encoding sarcomeric proteins
- most commonly autosomal dominant with variable penetrance
Causes of restrictive cardiomyopathy
- idiopathic
- radiation fibrosis
- amyloidosis
- sarcoidosis
- metastatic tumors
- inborn errors of metabolism with metabolite accumulation
Gross features of restrictive cardiomyopathy
- normal ventricular size and thickness
- often biatrial dilatation
Etiologies of myocarditis
- viral (most common, coxsackie and enterovirus)
- parasitic (chagas disease, toxo)
- bacteria (diphtheria)
- hypersensitivity (e.g. to drug)
- connective tissue disease (e.g. lupus)
- sarcoid
- poststrep
basically: infectious, immune, other
Most common chemotherapeutic drugs to the heart
-doxorubicin and danorubicin (anthracyclines): often lead to dilated cardiomyopathy; dose dependent
Cardiac effects of iron overload
- systolic dysfunction, possibly due to ROS generation
- perinuclear deposition of iron
- rust brown heart resembling dilated cardiomyopathY
Cardiac effects of thyroid disease
Hyperthyroidism: nonspecific hypertrophy with ischemic foci
Hypothyroidism (myxedema heart): flabby, dilated heart with interstitial mucopolysaccharides
Three categories of causes of pericarditis
Infectious
Immune-mediated
Other
Causes of serous pericarditis
- usually non-infectious immune mediated
- lupus
- scleroderma
- tumors
- uremia
Causes of fibrinous pericarditis
- post MI
- lupus
- radiation
- trauma
- uremia
- rheumatic fever
Most common cardiac tumors
- myxoma
- fibroma
- lipoma
- papillary fibroelastoma
- rhabdomyoma
- angiosarcoma
- other sarcomas
Chromosomal abnormalities in cardiac myxoma
-abnormalities of chr 12 or 17
Clinical manifestation of cardiac myxomas
- obstruction
- embolization
- generalized fatigue, malaise due to elaboration of cytokines by the tumor
Carney complex
- autosomal dominant mutation of PRKAR1, chr 17 (acts as a tumor suppressor)
- cardiac and cutaneous myxomas
- pigmented skin lesions
- endocrine hyperactivity
What is graft arteriopathy?
- diffuse stenosing intimal proliferation of coronary arteries in cardiac transplants
- major cause of graft failure
- may be related to low-level chronic rejection
- may result in silent MI because the transplanted heart is denervated
