Pericardial Tamponade Flashcards
great vessels of the heart
the aorta, pulmonary artery, pulmonary vein and the superior and inferior vena cava
what is the pericardium
The pericardium is a fibro-serous, fluid filled sack that surrounds the muscular body of the heart and the roots of the great vessels
layers of the pericardium
a tough external layer known as the fibrous pericardium, and a thin, internal layer known as the serous pericardium
layers of the serous pericardium
the outer parietal layer which lines the internal surface of the fibrous pericardium and the internal visceral layer which forms the outer layer of the heart (also known as the epicardium).
cells of the serous pericardium
single sheet of epithelial cells, known as mesothelium.
pericardial cavity
Found between the outer and inner serous layers, is the pericardial cavity, which contains a small amount of lubricating serous fluid.
fluid in the pericardial space
Normally there is 15-30 ml of fluid in the pericardial space between the parietal and visceral pericardium. This fluid serves to minimize the friction generated by the heart as it contracts and moves about within the thoracic cavity.
pathophysiology of tamponade
The fibrous pericardium is relatively inextensible and can pose a problem when there is an accumulation of fluid, known as pericardial effusion, within the pericardial cavity.
This rigidity means that the heart is subject to the resulting increased pressure. The chambers can become compressed, thus compromising cardiac output.
Tamponade is the physiologic state when the pressure from intra-pericardial fluid accumulation increases, compressing the heart and causing decreased cardiac output.
Once you’ve reached the limit of the pericardial compliance, pressure finally does start to increase, first equalizing with RV diastolic pressure then the left. Cardiac output (CO) drops, so contractility and rate increase to compensate.
stages of tamponade
- Fluid filling the recesses of the parietal pericardium
- Fluid accumulating faster than the rate of the parietal pericardium’s ability to stretch
- Accumulation that exceeds the body’s ability to increase blood volume to support RV filling pressure
With slow accumulation of fluid, the compliant parietal pericardium stretches without much change in pressure. Gradual accumulation of fluid is well tolerated as some dialysis patients chronically have up to one litre of pericardial effusion. Lower-right-sided pressures result in evidence of compressive effects on the right heart first.
Rapid accumulation is bad. The pericardium doesn’t stretch and the CO drops dramatically. Rapid pericardial fluid accumulation leads to elevated intra-pericardial pressure and myocardial compression. The rate of accumulation rather than volume is responsible for hemodynamic instability.
causes of tamponade
Whatever can cause an effusion can cause tamponade
Classified as Traumatic vs Non-traumatic
non- traumatic causes
Malignancy
Uremia/ESRF
Radiation
Drug reaction
Autoimmune disorders
TB
Iatrogenic
Aortic dissection
Idiopathic
symptoms of pericardial tamponade
*dyspnea (most common, 87-88% sensitivity)
*chest pain, fullness, palpitations
*nausea, abdo pain (hepatic/ visceral congestion), anorexia
*dysphagia
*lethargy, weakness, fatigue (decreased CO)
*fever
*cough
clinical findings
*distended neck veins
*muffled heart sounds
*hypotension
*tachycardia (77% sensitivity)
*pulsus paradoxus
*absent apex beat
*tachypnoea
Chest pain, cough, fever, lethargy, palpitations occurrence
<25%
beck triad
Hypotension
Jugular venous distension
Diminished heart sounds
Only 33% of patients have all three