heart 1 Flashcards
Myocardium histology includes
intercalated discs
Valve histology
(ventricularis* [v], spongiosa [s], and fibrosa [f]).
Pulmonary valve histology is similar but the atrioventricular valves will be thinner and have an atrialis, instead of a ventricularis, layer.
Chambers in the aging heart
Increased left atrial cavity size
Decreased left ventricular cavity size
** Sigmoid-shaped ventricular septum
Valves in the aging heart
** Aortic valve calcific deposits
**Mitral valve annular calcific deposits
Fibrous thickening of leaflets
Buckling of mitral leaflets toward the left atrium
Lambl excrescences
epicardial coronary arteries in the aging heart
** Tortuosity
Diminished compliance
Calcific deposits
** Atherosclerotic plaque
Myocardium in the aging heart
Decreased mass Increased subepicardial fat ** Brown atrophy ** Lipofuscin deposition (aging pigment) ** Basophilic degeneration (glycogen breakdown) ** Amyloid deposits
the aging aorta
** Dilated ascending aorta with rightward shift
Elongated (tortuous) thoracic aorta
Sinotubular junction calcific deposits
Elastic fragmentation and collagen accumulation
atherosclerotic plaque
cardiac death statistics– what have gone up?
↑ Congenital heart disease deaths
↑ Hypertensive heart disease deaths
Normal Cardiac Function and Cardiac Reserve
Cardiac output is ~10-20% of maximum at rest in normal adults
“Cardiac Reserve” 5-fold margin for increased output
Have lost 70-80% of cardiac function by the time patient is symptomatic!
Heart disease is predominantly a long-term chronic disease with superimposed acute episodes
Cardiac Dysfunction Six Basic Causes
Pump failure - diminished myocardial contractility
Primary cardiomyopathy; ischemic cardiac disease
Obstruction to blood flow through the heart
Stenotic valvular disease; hypertensive disease
Regurgitant flow
Valvular disease with incompetence
Shunted flow- Congenital heart diseases
Disorders of cardiac conduction- Atrial fibrillation; ventricular tachycardia
Disruption of continuity of the circulatory system- Gunshot wound; ventricular rupture; ruptured aneurysm
Cardiac Compensation
Activation of neurohumoral systems
- Norepinephrine from adrenergic nerves
- Renin-angiotensin-aldosterone system
- Natriuretic peptides
Myocardial adaptations - ventricular remodeling
Frank-Starling mechanism - enhance contractility and stroke volume
Natriuretic Peptides
A-type natriuretic peptide produced by specialized atrial myocytes with specific atrial granules and released with atrial distension
B-type natriuretic peptide (BNP) produced by ventricles (2ry to increased pressure) and is used for determination of CHF
C-type produced by endothelial cells (secondary to shear stress)
** Cause vasodilation, natriuresis and diuresis
Antithesis of renin-angiotensin-aldosterone system
causes and consequences of cardiac hypertrophy
pressure overload/ volume overload (Hypertension, valve disease, MI) –> increased work and wall stress and cell stretch –> hypertrophy and/ or dilation
“Congestive Heart Failure” (CHF)
When dysfunction is chronic and symptomatic
Cardiac Hypertrophy Pathophysiology
Increased physiologic need by a normal heart (aerobic exercise)
Cardiac failure increases workload per myocyte due to overall decreased intrinsic myocardial contractility (ischemia, etc.)
Myocyte hypertrophy - Response available for increased cardiac
workload per myocardial fiber
(Myocyte hyperplasia does not occur in adult ventricle)
Cardiac hypertrophy – increase in ventricular thickness or weight
Cardiomegaly - increase in heart size or weight
heart: weight in grams for normal and abnormal
Normal: Male 300-350 gm; Female 250-300 gm
350-600 gm: Pulmonary HTN, IHD
400-800 gm: Systemic HTN, aortic stenosis, mitral regurgitation, dilated cardiomyopathy
600-1000 gm: Aortic regurgitation, hypertrophic cardiomyopathy
Cardiac Hypertrophy Pathologic Findings
“Pressure Overload” Hypertrophy = Concentric Hypertrophy
-increase in the thickness of wall subjected to the increased workload
Left ventricle: systemic hypertension or aortic stenosis
Right ventricle: cor pulmonale
“Volume Overload” Hypertrophy = Eccentric Hypertrophy
- chamber dilatation caused by volume overload stimulus
Overall cardiac muscle mass is increased
Ventricular wall thickness is near normal
Can be seen with ischemia, valve disorders, congenital heart disease, etc.
Congestive Heart Failure (CHF)
Cardiac Failure due to insufficient pump rate to meet metabolic demands and/or pump can marginally meet demands with elevated filling pressure
Forward and Backward failure in CHF
Forward failure - Diminished cardiac output
Systolic dysfunction - progressive deterioration of myocardial contractility
Diastolic dysfunction - Inability heart chambers to relax (distend) sufficiently to fill during diastole
Backward failure - Damming of blood in the venous system
Left-side failure leads to accumulation of fluid within the lungs and pleural cavities
Right-side failure leads to accumulation of fluid in all other body sites and all body cavities
Left-Sided Heart Failure
Chronic: Slowly progressive failure (insidious onset) which may over time develop sufficient severity to cause right sided heart failure
Acute: Rapidly progressive fatal course (with acute pulmonary edema) – Medical Emergency with 50% mortality
Most commonly caused by Ischemic heart disease Hypertensive heart disease Aortic and mitral valvular disease Primary nonischemic myocardial disease (cardiomyopathy)
Lab testing for left-sided heart failure
Laboratory testing : B-type natriuretic peptide produced by ventricles (2ry to increased pressure); BNP and NT pro-BNP tests available
BNP >500 pg/mL are most consistent with CHF
BNP less than 100 pg/mL unlikely to be CHF
Left-Sided Heart Failure Cardiovascular Pathologic Findings
Cardiomegaly: Hypertrophy +/- chamber dilatation
Secondary enlargement of the left atrium (eccentric hypertrophy)
Can lead to mitral valve regurgitation and atrial fibrillation
Tachycardia – increased adrenergic activity
Third heart sound (S3 gallup) - occurs during ventricular filling (diastole)
Systolic murmur - if develop mitral regurgitation
Hepatojugular reflux - distention of the jugular vein induced by applying manual pressure over the liver (elevated filling pressure in left-sided heart failure)
Left-Sided Heart Failure Extracardiac Effects
Lung pathology: pulmonary basilar crackles (rales) +/- pleural effusions
Flash pulmonary edema
siderophages (heart failure cells)- long-term
Dyspnea
Orthopnea
Paroxysmal nocturnal dyspnea
Kidney- renal hypoperfusion
Brain- hypoxic encephalopathy
Right-Sided Heart Failure
Most commonly a consequence of left-sided heart failure
↑ pressure in the pulmonary circulation →↑workload right ventricle →right-sided heart failure
“Pure” or isolated (no left-sided dysfunction) right-sided failure
- Uncommon
- Cardiac hypertrophy and dilatation confined to the right atrium and ventricle
- Sequela of severe chronic pulmonary hypertension
- ** Cor Pulmonale = Heart disease secondary to lung disease