Pathophysiology of Pericardial DiseaseIMS 350

Pericardium - AnatomyNormal pericardium is a fibro-serous sac which surrounds the heart and adjoining portions of the great vessels. The inner visceral layer, also known as the epicardium, consists of a thin layer of mesothelial cells closely adherent to the surface of the heart. The epicardium is reflected onto the surface of the outer fibrous layer with which it forms the parietal pericardium.The parietal pericardium consists of collagenous fibrous tissue and elastic fibrils. Between the two layers lies the pericardial space, which contains approximately 10-50ml of fluid, which is an ultrafiltrate of plasma.Drainage of pericardial fluid is via right lymphatic duct and thoracic duct.

Pericardium: AnatomyPericardial Layers: Visceral layer Parietal layer Fibrous pericardium

Function of the Pericardium1. Stabilization of the heart within the thoracic cavity by virtue of its ligamentous attachments -- limiting the hearts motion.

2. Protection of the heart from mechanical trauma and infection from adjoining structures.

3. The pericardial fluid functions as a lubricant and decreases friction of cardiac surface during systole and diastole.

4. Prevention of excessive dilation of heart especially during sudden rise in intra-cardiac volume (e.g. acute aortic or mitral regurgitation).

Etiologies of PericarditisI. INFECTIVE1. VIRAL - Coxsackie A and B, Influenza, adenovirus, HIV, etc.2. BACTERIAL - Staphylococcus, pneumococcus, tuberculosis, etc.3. FUNGAL - Candida4. PARASITIC - Amoeba, candida, etc.II. AUTOIMMUNE DISORDERS1. Systemic lupus erythematosus (SLE)2. Drug-Induced lupus (e.g. Hydralazine, Procainamide)3. Rheumatoid Arthritis4. Post Cardiac Injury Syndromes i.e. postmyocardial Infarction (Dressler's) Syndrome, postcardiotomy syndrome, etc.III. NEOPLASM1. Primary mesothelioma2. Secondary, metastatic3. Direct extension from adjoining tumorIV. RADIATION PERICARDITISV. RENAL FAILURE (uremia)VI. TRAUMATIC CARDIAC INJURY1. Penetrating - stab wound, bullet wound2. Blunt non-penetrating - automobile steering wheel accidentVII. IDIOPATHIC

Pathogenesis1) Vasodilation: transudation of fluid2) Increased vascular permeability leakage of protein3) Leukocyte exudationneutrophils and mononuclear cells Pathologydepends on underlying cause and severity of inflammationserous pericarditisserofibrinous pericarditissuppurative (purulent) pericarditishemorrhagic pericarditis

Clinical Features of Acute PericarditisIdiopathic/viral* Pleuritic Chest pain* Fever* Pericardial Friction Rub3 component:a) atrial or pre-systolic componentb) ventricular systolic component (loudest)c) ventricular diastolic component* EKG: diffuse ST elevation PR segment depression

EKG findings in Pericarditis

Diagnostic TestsEchocardiogram: Pericardial effusion N.B.: absence does not rule out pericarditis N.B.: Pericarditis is a clinical diagnosis, not an Echo diagnosis!

Blood tests: PPD, RF, ANA Viral titers

Search for malignancy

Pericardiocentesis:low diagnostic yielddone therapeutically

TreatmentPain reliefanalgesics and anti-inflammatoryASA/NSAIDs

Steroids for recurring pericarditis

Antibiotics/drainage for purulent pericarditis

Dialysis for uremic pericarditis

Neoplastic: XRT, chemotherapy

Pericardial EffusionNormal 15-50 ml of fluidETIOLOGY1. Inflammation from infection, immunologic process.2. Trauma causing bleeding in pericardial space.3. Noninfectious conditions such as:a. increase in pulmonary hydrostatic pressure e.g. congestive heart failure.b. increase in capillary permeability e.g. hypothyroidismc. decrease in plasma oncotic pressure e.g. cirrhosis.4. Decreased drainage of pericardial fluid due to obstruction of thoracic duct as a result of malignancy or damage during surgery.

Effusion may be serous, serofibrinous, suppurative, chylous, or hemorrhagic depending on the etiology. Viral effusions are usually serous or serofibrinous Malignant effusions are usually hemorrhagic.

PathophysiologyPericardium relatively stiffSymptoms of cardiac compression dependant on:1. Volume of fluid2. Rate of fluid accumulation3. Compliance characteristics of the pericardium

A. Sudden increase of small amount of fluid (e.g. trauma)B. Slow accumulation of large amount of fluid (e.g. CHF)

Clinical featuresSmall effusions do not produce hemodynamic abnormalities.

Large effusions, in addition to causing hemodynamic compromise, may lead to compression of adjoining structures and produce symptoms of:dysphagia (compression of esophagus)hoarseness (recurrent laryngeal nerve compression)hiccups (diaphragmatic stimulation)dyspnea (pleural inflammation/effusion)

Physical FindingsPhysical Findings:Muffled heart soundsParadoxically reduced intensity of rubEwart's sign:Compression of lung leading to an area of consolidation in the left infrascapular region (atalectasis, detected as dullness to percussion and bronchial breathing)

Diagnostic studiesCXR: water bottle shaped heart

EKG: low voltage electrical alternans

Echocardiogram

Cardiac TamponadeFluid under high pressure compresses the cardiac chambers:acute: trauma, LV rupture may not be very largegradual: large effusion, due to any etiology of acute pericarditis

CardiacTamponade -- PathophysiologyAccumulation of fluid under high pressure: compresses cardiac chambers & impairs diastolic filling of both ventricles

SVvenous pressures

COsystemic pulmonary congestion

Hypotension/shockJVD ralesReflex tachycardiahepatomegalyascitesperipheral edema

Tamponade-- Clinical FeaturesSymptoms:Acute: (trauma, LV rupture)profound hypotensionconfusion/agitationSlow/Progressive large effusion (weeks)Fatigue (CO)DyspneaJVDSigns:TachycardiaHypotensionrales/edema/ascitesmuffled heart soundspulsus paradoxus

Pulsus ParadoxusIntrapericardial pressure (IPP) tracks intrathoracic pressure. Inspiration: negative intrathoracic pressure is transmitted to the pericardial space IPP blood return to the right ventricle jugular venous and right atrial pressures right ventricular volume interventricular septum shifts towards the left ventricle left ventricular volume LV stroke volume blood pressure (

Pulsus ParadoxusExaggeration of normal physiology> 10 mm Hg drop in BPwith inspiration

Tamponade -- Diagnosis

EKG: low voltage, sinus tachycardia,electrical alternans

Echocardiographypericardial effusion (r/o other etiologies in dif dx)RA and RV diastolic collapse

Right Heart CatheterizationCatheterization Findings:

Elevated RA and RV diastolic pressuresEqualized diastolic pressuresBlunted y descent in RA tracingy descent: early diastolic filling (atrial emptying) BP and Pulsus paradoxusPericardial pressure = RA pressure

Jugular venous pressure wavesNormal JVP contours(1) A-wave 1) results from ATRIAL contraction2) Timing - PRESYSTOLIC3) Peak of the a-wave near S1(2) V-wave 1) results from PASSIVE filling of the right atrium while the tricuspid valve is closed during ventricular systole (Remember the V-wave is a "V"ILLING WAVE)2) Large V-waves on the left side of the heart may be seen with mitral regurgitation, atrial septal defect, ventricular septal defect. The v-wave in the jugular venous pulse reflects right atrial events. To see the v-wave on the left side of the heart Swan-Ganz monitoring is needed3) timing - peaks just after S2(3) X-descent 1) results from ATRIAL RELAXATION2) timing - occurs during ventricular systole, at the same time as the carotid pulse occurs(4) Y-descent 1) results from a FALL in right atrial pressure associated with opening of the tricuspid valve2) timing - occurs during ventricular diastole(5) Generalizations 1) the A-wave in a normal individual is always larger than the V-wave2) the X-descent is MORE PROMINENT than the Y-descent

RA Pressure Tracinga wave: atrial contraction

v wave: passive filling of atria during ventricular systole with mv/tv closed

y descent: early atrial emptying with mv/tv open (early passive filling of ventricle)

Tamponade:blunted y descent (impaired rapid ventricular filling due to compression by high pericardial pressure)

Tamponade

Tamponade -- TreatmentPericardiocentesis

Pericardial Window

Balloon PericardiotomyPre-pericardiocentisisPost-pericardiocentesis

Constrictive PericarditisLate complication of pericardial diseaseFibrous scar formationFusion of pericardial layersCalcification further stiffens pericardiumEtiologies:any cause of pericarditisidiopathicpost-surgerytuberculosisradiationneoplasm

PathophysiologyRigid, scarred pericardium encircles heart: Systolic contraction normal Inhibits diastolic filling of both ventricles

SVvenous pressures

COsystemic pulmonary congestion

Hypotension/shockJVD ralesReflex tachycardiahepatomegalyascitesperipheral edema

Physical examHR, BP

ascites, edema, hepatomegaly

early diastolic knockafter S2sudden cessation of ventricular diastolic filling imposedby rigid pericardial sac

Kussmauls sign

Kussmauls Signinspiration: intrathoracic pressure, venous return to thorax intrathoracic pressure not transmitted though to RV no pulsus paradoxus! no inspiratory augmentation of RV filling (rigid pericardium) intrathoracic systemic veins become distended JVP rises with inspiration (normally falls)

DiagnosisCXR: calcified cardiac silhouetteEKG: non-specificCT or MRI: pericardial thickening

Cardiac CatheterizationProminent y descent: dip and plateau:rapid atrial emptying rapid ventricular fillingthen abrupt cessation of blood flow due to rigid pericardiumElevated and equalized diastolic pressures (RA=RVEDP=PAD=PCW)

Constriction vs. RestrictionSimilar presentation and physiology, important to differentiate asconstriction is treatable by pericardiectomyMajority of diseases causing restriction are not treatable

Constrictive PericarditisKussmaulsRV=LV,dip & plateauEqualized diastolic pressuresTachycardia, low voltageThickened pericardiumThickened pericardium

Constriction vs. Tamponade SummaryTAMPONADELow cardiac output stateJVD presentNO Kussmauls signEqualized diastolic pressures RA: blunted y descentDecreased heart sounds

CONSTRICTIONLow cardiac output stateJVD presentKussmauls signEqualized diastolic pressuresRA: rapid y descentPericardial knock

Constriction vs. Tamponade SummaryTAMPONADEPulsus paradoxus:PresentEcho/MRI:Normal systolic function Large effusion RA & RV compressionTreatment: PericardiocentesisCONSTRICTIONPulsus paradoxus:AbsentEcho/MRI:Normal systolic functionNo effusion Pericardial thickeningTreatment:Pericardial stripping