PERICARDIUM

Dr Ramachandra

Enclosed lubricated space for the beating heart/ fix it in chest

Rule of Two’s

Double-layered: visceral=epicardium & parietal Thickness=2 mm Fibroblastic Parietal =Meshwork of 2 fibres collagen (types I and III) and elastic. Pericardial fluid volume=2x10 ml=20-30ml Two sinuses=Oblique(4PV AND IVC-SVC) & Transverse=AO and PA Pressure in pericardium 2mmHg lower than

intrathoracic pressure. Innervation :2=ANS(parasympathetic (

vagus)/sympathetic ( stellate ganglia) and somatic= the phrenic nerve.

Embryology

From mesoderm (the pleuropericardial membranes) that divide the primitive thoracic cavity of the intraembryonic coelom into pericardial and pleural compartments. The endocardial heart tube invaginates into the developing pericardial cavity, whereby the innermost serosal layer adheres to the myocardium and then folds back onto itself to create visceral and parietal layers.This process of invagination eventually results in suspending the adult heart within the developing pericardial cavity by blood vessels at its cranial and caudal attachments.The pericardium receives its blood supply via the internal mammary artery. Phrenic nerves are enveloped in the pleuropericardial membranes, and in the adult, reach the diaphragm by traveling through the fibrous pericardium .

Physiology

Pericardial fluid act as lubricant between visceral and parietal layers to facilitate frictionless beating of the heart. The intrapericardial fluid function as a reservoir of paracrine modulators, notably compounds such as prostanoids, natriuretic peptides, and endothelins, that may regulate sympathetic tone, coronary vasomotor tone, heart rate, and bloodpressure, but also immunologically active moieties, such as complement factors. Pericardial fluid is in equilibrium with pleural fluid, as there is hydraulic conductance across the parietal pericardium when intrapericardial pressures exceed pleural pressures.Numerous attachments from the pericardium to other thoracic structures secure the heart in place within the chest cavity. Cranially, the reflections on great vessels interdigitate with vascular adventitia to fasten the superior borders of the pericardium; a diaphragmatic tendon anchors the caudal end.Ventrally the pericardium connects with the interior of the sternum (superior and inferior pericaridosternal ligaments), and dorsally it affixes to the esophagus and spine.

Contd

The fibrous nature of the pericardium likely also serves as a barrier to insulate the heart from exogenous tumors and spread of infections.Despite its fibrous character, the pericardium rests at slightly lower pressures (_3 to _6 mm Hg) compared to the rest of the intrathoracic cavity and is able to transmit hanges in intrathoracic pressures with respiration.Intact pericardium is rather nondistensible and provides a strong mechanical constraint on overall heart volume and chamber enlargement. Important consequences of nondistensibility are equalizing compliance of right and left ventricles as well as interdependence of the cardiac chambers.Interdependence occurs because total intrapercardial volume (namely pericardial cavity and cardiac chamber volume) is fixed in the short term, and expansion of 1 chamber necessarily impedes expansion of another.

Contd.......

Especially as regards ventricular interdependence,acute expansion of either right or left ventricular volume will impair filling of the other chamber, at the limit resulting in signs such as the pulsus paradoxus. The same principles apply in acute pericardial effusion and tamponade physiology, because there is very little reserve volume for expansion in the pericardial space before intrapericardial pressure rises Sharply. In situations where pericardial effusion develops gradually,pericardial compliance can increase to accommodate significant fluid volumes, often a liter or more. Efferent painful stimuli (eg, inflammation, distention) are carried via phrenic nerves and stellate ganglion; however, not every surface of the pericardium is innervated. The pericardium appears insensate to temperature and vibration.

Contd

Interdependence occurs because total intrapercardial volume (namely pericardial cavity and cardiac chamber volume) is fixed in the short term, and expansion of 1 chamber necessarily impedes expansion of another. Especially as regards ventricular interdependence,acute expansion of either right or left ventricular volume will impair filling of the other chamber, at the limit resulting in signs such as the pulsus paradoxus. The same principles apply in acute pericardial effusion and tamponade physiology, because there is very little reserve volume for expansion in the pericardial space before intrapericardial pressure rises Sharply. In situations where pericardial effusion develops gradually,pericardial compliance can increase to accommodate significant fluid volumes, often a liter or more. Efferent painful stimuli (eg, inflammation, distention) are carried via phrenic nerves and stellate ganglion; however, not every surface of the pericardium is innervated. The pericardium appears insensate to temperature and vibration.

Congenital defects

Absence:“stabbing” chest pains with “heart shifting

RBBB/Clockwise loop, levoposition and posterior rotation,of the cardiac apex, as well as pathognomonic interdigitation of lung tissue between the inferior heart surface and diaphragm as well as between the aorta and pulmonary artery. “teardrop” shaped, because of atrial elongation and ventricle widening in the absence of typical pericardial tethering.

Pericardial Masses(embryonic coelomic cavity.)

Epicardial Fat

The closest D/D of pericardial effusion

Pericardial tumors

Pericardial collection

Pericardial Effusions

Mild:<5mm Moerate:5-10mm Severe(Tamponade)>10mm In acute situation even mild may cause

tamponade

Pericarditis

Infiltration is the sine qua non of pericarditis

self-limited(mostly) 80-90% of cases are idiopathic, “bread-and-butter

pericardium”=supporation Peri-infarction - 5%(TLT+) vs 10-20%

(TLT-Ve), Dressler’s < 1% Dx:At least 2 of 4 cardinal features

Contd.......

Unique pain radiation to the trapezius ridge

The pericardial friction rub

A triphasic(50%) cadence with a discrete “sandpaper” sound occurring with atrial systole, ventricular systole, and early ventricular diastole. 100% specific but evanescent ,less sensitive.

EKG changes in acute pericarditis

STAGE-I

Recurrent or Relapsing Pericarditis Latent periods of up to 6 weeks 12 weeks of therapy of NSAID in tappering CORE trial:Colchicine (1-2 mg followed by 0.5 mg daily or twice

daily for 6 months; addition to high-dose aspirin therapy for first recurrence of idiopathic,viral, or autoimmune pericarditis,24% recurrence at 18 months as compared to 51% in the control, a two-thirds reduction (10% vs 31%) in symptoms at 72 hours(CLASS I-EHA)

Steroid for auto immuno causes-0.5mg-1mg/Kg Intrapericardial corticosteroids(A single instillation of

triamcinolone (300mg/m2 to 600 mg/m2 in 100 mL isotonic saline) over 24 hours on

thebackground of maintenance colchicine therapy prevented 84%

recurrencesat 1 year Immunosuppresants:Cyclosporine /Azathioprine, remains

investigational.

Hemodynamic Consequences

Claude Schaeffer Beck (1894 – 1971) was a pioneer American cardiac surgeon, famous for innovating various cardiac surgery techniques, and performing the first defibrillation in 1947.[ He was the first American professor of cardiovascular surgery, from 1952 through 1965.

1930

Tamponade physiology

Resting intrapericardial pressure is 3 to 6 mm Hg less than the diastolic pressures in the cardiac chambers and thus does not affect intracardiac blood flows with 2-4 mmHg respiratory variation.

Pericardial pressure at which the point where cardiac filling is compromised.

Pericardial fluid becomes like a fifth cardiac chamber, occupying space within the pericardium and thus limiting the ability of atria and ventricles to expand and fill appropriately ( impaired diastolic compliance).

May be slow or fast

Contd........

Chamber-filling pressure is the ∆ between intracardiac and intrapericardial pressures

Mean diastolic pressures equalize across cardiac chambers as they need to exceed the increased pressures in the intrapericardial space

Physiologicalventricular interdependence becomes magnified due to isolation of the heart from normal respiratory ∆

Inspiration will increase right-sided flows at the expense of the left-sided chambers, thus reducing left-sided flow

Contd.......

Contd....

Left- and right-ventricular filling pressures are usually elevated at 15-20 mm Hg in tamponade. However, so-called low-pressure tamponade with much lower ventricular filling pressures can occur in patients with reduced blood volume, eg, dehydration, overdiuresis, or hemorrhage.

A pulsus paradoxus ≥10 mm Hg a likelihood ratio of 3.3 for the presence of tamponade

Value ≤10 confers a negative likelihood ratio of

0.03 PP= 20 mm Hg ≥75% Tamponade Palpable pulsus (or “total paradox”) in

almost 20%

DX of pulsus paradoxus

Pulsus suppression

RV or LV are markedly noncompliant= severe left ventricular (LV) failure, right ventricular hypertrophy, left ventricular hypertrophy, acute myocardial infarction,severe aortic insufficiency (elevated left ventricular end diastolicpressure and damping of respiratory variation), or in uremia, atrial septal defect (as venous return is offset by right to left shunting), and pericardial adhesions

QRS alternans

QRS alternans is present in 20% and total

alternans (of P, QRS, and T waves) in 8% of patients.

Low voltage complex

Echocardiographic signs of tamponade

ROVT collapse is quite consistent

Inflow and out flow doppler

Mitral 35% and aortic 25% variation and TV=80%

Pericardial Constriction

≥ 5mm echo and ≥4mm CT(N=1-2mm,<4mm)

CP Physiology with non thickened 20% Kussmaul’s sign(JVP distension in

inspiration) pericardial knock≥frequency than S3 Friedrich’s sign=Rapid Y descent of early

diastolic suction “square-root”=sign of no further filling

occurs after early diastole Equalized diastolic in all 4 chambers

Hemodynamic=CATH/ECHO

diastolic function are load-dependent

Echo Doppler

CT Scan

CT is the best imaging ≥4 mm diagnostic sigmoid-shaped ventricular septum Persistent concordance of tagged signals

between the pericardium and the myocardium during both systolic and the diastolic phases is a sign of pericardial adhesions and is a reliable sign of pericardial constriction.

CMRI+CE T1 Weighted

More soft tissue clarification at more cost

Pericardial biopsy

Add diagnostic yield only 5-6%, add 29-54% in in tamponade

Thanks, you came so long with me.....