Cardiac
Cardiac Tumors
Cardiac Tumors •
Rare
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Usually benign and pedunculated
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Three types: –
Cardiac myxomas
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Rhabdomyomas
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Metastatic tumors
Right atrial
With stalk
Cardiac Myxomas •
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The most common primary adult tumor (35-50%) Most arise from the left atrium (90%) Complications: –
“Ball-valve” effect may obstruct the mitral valve orifice in over half half of patients patients with with myxomas myxomas of the left atrium •
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Blocks diastolic filling of the ventricle, stimulating mitral valve valve stenos stenosis is -> may cause cause syncop syncopal al episodes episodes
One third of these patients die of embolization of embolization of the tumor to the brain
Dx: transe transesopha sophageal geal ultrasoun ultrasound d
Stellate Stellate cells and and fibroblas fibroblasts ts
Amorphous extracellular matrix
Histology of Cardiac Myxomas •
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Loose Loose myxoid yxoid matrix matrix Abundan Abundantt prot proteog eogly lycan canss with with ste stella llate te cells cells within the matrix
Grossly
Striated Striated muscle (“Spider”) (“Spider” ) cells
Rhabdomyomas •
Most common primary cardiac tumor in infan infants ts and children –
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Forms Forms hamartomas hamartomas in the myocar myocardium dium Almost all are multiple –
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Involve Involve both the left and right ventricles, and the atria in 1/3 of cases Projects into the cardiac chamber in ½ of cases
Grossly: –
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Major association with tuberous sclerosis
Pale gray masses, up to several centimeters
Histologically: –
Derived from striated muscle cells with abundant glycogen
Metastatic Metastatic Breast Cancer
Metastatic Melanoma to the Heart
Metastatic Tumors to the Heart •
Metastasis is more common than primary tumors –
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The pericardium is the most common site for metastasis –
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Derived from cancers of the lungs, breast, GI tract, lymphomas, leukemias, malignant melanomas
Leads Leads to pericarditi pericarditiss and effusio effusions ns
Metastatic cancers of the myocardium ma result in manifestations of restrictive cardiomyopathy
Heart Emboli
Types of Emboli •
Thromboemboli –
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Liquid Emboli –
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Fat emboli Amniotic fluid emboli
Gas Emboli –
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Fragments of thrombi Most common Infected thrombi give rise to septic emboli
Air emboli Decompression Decompression sickness
Solid Particle Emboli –
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Cholesterol crystals from atherosclerotic plaques Tumor cells Bone marrow emboli Bullets
Classification of Emboli •
Venous emboli –
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Originate in the heart, aorta, and major arteries Cause infar infarction ction
Paradoxical Emboli –
Sources of Venous Emboli
Typically lodge in pulmonary artery and branches -> pulmonary embolism
Arterial emboli –
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Originate in veins
Venous emboli that reach the arterial circulation through an atrial septal defect
Pulmonary Embolism •
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Pulmonary Saddle Embolus
Most important complication of venous of venous emboli Saddle emboli @ entry of main pulmonary artery –
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Wedge-shaped pulmonary infarct
Often lethal
Smaller emboli lodge in minor branches and cause wedge-shaped infarcts
Arterial Emboli •
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Most originate from endocardium, valvular thrombi, ulcerated atherosclerotic plaques Tend to lodge lo dge in mediumsized and smaller arteries Lodge in: Brain (middle cerebral artery) Spleen Kidneys Intestines –
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Sources of Arterial Emboli
Fat Embolism •
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Following fractures of long bones -> platelets adhere to fat globules -> thrombocytopenia Fat Embolism Syndrome appears 1-3 days after injury –
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Respiratory symptoms: ARDS Neurologic symptoms: mental changes
Amniotic Fluid Embolism •
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Entry of amniotic fluid into the maternal circulation Usually occurs @ the end of labor Histology: fet fetal al squamous cells within pulmonary vasculature vasculature Clinical presentation: presentation: –
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Fetal Epithelial Squames
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Sudden severe dyspnea Cyanosis Hypotensive shock Seizures and coma Pulmonary edema DIC
Bone Marrow Embolism •
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Usually after cardiac resuscitation No symptoms
Decompression Decompression Sickness •
Form of gas embolism
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Seen in scuba divers divers
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Nitrogen gas released from solution during rapid ascent -> obstructing blood flow
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Commonly known as the “bends”
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Temporary muscle, joint pain
Caisson Disease •
Chronic decompression sickness where vascular obstruction causes avascular necrosis of bone, bone, primarily affecting head of the femur, tibia, and humerus
Hyperemia •
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Accumulation of blood in the peripheral circulation Active hyperemia: dilatation of the arterioles mediated by neural signals Passive congestive: increased venous back pressure Consequence of CHF Associated with pulmonary edema with L heart failure failure RBC’s taken up by alveolar macrophages = hemosiderin-laden macrophages (heart failur failure e cells) Associated with passive liver congestion (Nutmeg liver) with R heart failure –
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Hemosiderin-Laden Macrophages
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Hemorrhage •
Cardiac –
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Trauma, aortic aneurysm dilation, dissection
Arterial –
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Often fatal
Aortic –
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Resulting from a stab wound, or a softened heart muscle from a MI can result in ventricular rupture -> pericardial tamponade
Penetrating wounds, fractured bones Usually fatal
Venous –
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Usually traumatic; blood flows out of the body -> hypovolemia May fill body cavities and form hematomas
Petechiae, purpura, and ecchymosis •
Petechiae –
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Purpura –
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Small hemorrhages into skin, mucosa < 1mm in diameter Measure 1mm to 1cm
Ecchymoses –
Larger blotchy areas under the skin due to trauma
Fate of the Thrombi •
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Small thrombi are lysed or dissolved Larger thrombi stimulate inflammatory inflammatory cells -> granulation tissue deposition (organization organization); ); inflammatory cells of granulation tissue dissolve the thrombus & replaced with collagen Occlusive thrombi may be recanalized If thrombus cannot be organized or dissolved, may embolize
Thrombus Classification By Location •
Intramural –
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Attached to the arterial wall; typically cover ulcerated atheromas
Venous –
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May embolize
Arterial –
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Attached to mural endocardium; commonly found overlying a MI
Usually found in dilated veins Long-standing are organized by granulation tissue
Microvascular –
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Found in arterioles, capillaries, and venules Typical of Disseminated Intravascular Coagulation
Thrombus Classification Pathologically •
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Red Thrombi –
RBC’s and fibrin
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Thrombi in small vessels
Layered Thrombi –
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Lines of Zahn
Lines of Zahn: alternating white (fibrin) and red (RBC) lines Thrombi in larger arteries, veins, mural thrombi
Infarction •
Classified as red or white
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White infarcts –
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Red infarct of the intestine
Typical or arterial occlusion in solid organs (heart, kidneys) Paler than surrounding tissue; often rimmed by a thin red zone with extravasated blood
Red infarcts –
Typical of venous of venous obstruction involving intestines, or testes
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Also typical of organs with a dual blood supply, supply, i.e. liver l iver,, lungs
Septic infarcts –
Infarcts caused by infected thrombi, emboli
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Show signs of inflammation; may transform into an abscess
Shock •
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State of hypoperfusion of hypoperfusion of tissues -> hypoxia -> multiple organ failure Hypoxia -> shift from aerobic to anaerobic metabolism -> lactic acidosis Three mechanisms: –
Cardiogenic shock •
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Hypovolemic shock •
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Loss of circulatory volume, due to hemorrhage or water loss
Septic shock •
Pathogenesis of Septic Shock
Pump failure of the heart, often secondary to a MI
Most often due to endotoxin(LPS)-producing gram negative bacteria such as E.coli
3 Stages of Shock •
Nonprogressive –
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Progressive –
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Characterized Characterized by tissue hypoperfusion, and development of metabolic imbalances (acidosis) Metabolic acidosis -> dilates arterioles -> worsens CO -> stagnation of blood in pulmonary circulation -> favors ARDS (shock lungs) Urinary output falls due to constriction of the renal cortical vessels marking transition between reversible and irreversible stage
Irreversible –
Survival is not possible
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Multiple organ failure is usually present
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DIC is common
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Compilations of Shock
Initial phase when reflex compensatory mechanisms maintain perfusion of vital organs
Patients have marked hypotension, respiratory distress, acidosis, and anuria
ARDS with hyaline membranes •
In shock, alveolar capillaries in the lungs may necrotize and slough off to be covered and lined by fibrin (hyaline (hyaline membranes)) membranes
