Cardiac Tamponade Flashcards
(21 cards)
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 (the aorta, pulmonary artery, pulmonary vein and the superior and inferior vena cava).
The pericardium is made up of two main layers – a tough external layer known as the fibrous pericardium, and a thin, internal layer known as the serous pericardium
The serous pericardium is itself divided into two layers – 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). Each layer is made up of a single sheet of epithelial cells, known as mesothelium.
Found between the outer and inner serous layers, is the pericardial cavity, which contains a small amount of lubricating serous fluid.
normal amount of fluid in the pericardial sac?
15-30ml to reduce friction
what causes a pericardial effusion?
the fibrous pericardium is not extensible - hence if there is fluid accumulation of fluid, the heart takes the toll of the increases pressure and hence compromises cardiac output
what is a tamponade ?
pressure from intra-pericardial fluid accumulates, compresses the heart and decreases cardiac output
—> when pericardial compliance is reached pressure increases and dialyses with RV diastolic and then left
—> CO decreases hence HR increases to compensate
stages leading to a tamponade
- fluid fills the pericardium recesses
- fluid rate is faster than stretch ability
- blood volume increase cannot support the TV 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.
why is rapid fluid accumulation bad?
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 a tamponade
traumatic vs non-traumatic
NON-TRAUMATIC
- Malignancy
- Uremia/ESRF
- Radiation
- Drug reaction
- Autoimmune disorders
- TB
- Iatrogenic
- Aortic dissection
- Idiopathic
symptoms of a tamponade
> dyspnea
chest pain and palpitations
> nausea and abdominal pain
dysphagia
> weakness and fatigue
> fever
cough
clinical findings in tamponade
- increased JVP
- tachycardia and tachypnea
- muffled heart sounds and absent apex
- pulsus paradoxus
- hypotension
Triad associated
BECKS
1) hypotension
2) increased JVP - increased distension on inspiration ( paradox )
3) diminished heart sounds
33% have all three
sensitivity of pulsus paradoxus and patho
82%
Negative intrathoracic pressure with inspiration increases venous return to the right heart and causes increased filling of RV.
This overfilled RV bulges into the LV, decreasing its available volume.
Decreased left sided stroke volume means decreased cardiac output and decreased blood pressure with inhalation.
This ventricular interdependence happens normally.
The opposite occurs with exhalation. Increased pressures in the chest decreases right heart filling allowing more space for the left ventricle to fill and thus increased cardiac output. So, exhalation means higher blood pressures.
Exaggerated decrease in systolic blood pressure (>10 mm Hg) with inspiration
Also occurs with asthma, constrictive pericarditis, pulmonary embolism, and COPD
Ddx for tamponade
Massive PE
Tension Pneumothorax
SVC obstruction
Chronic constrictive pericarditis
Air embolism
RV Infarct
Severe CCF/cardiogenic shock
Extrapericardial compression: haematoma, tumour
tamponade on CXR
may have normal cardiac silhouette
200-250ml of fluid needed to actually cause cardiomegaly = bottle shape
possible ECG findings for tamponade
Sinus tachycardia
Decreased QRS voltage
Electrical alternans = alternating QRS amplitude
echo findings in tamponade
Pericardial effusion (Fluid around the heart will show up as a black stripe)
Collapse of the right atrium in late diastole
Collapse of the right ventricle free wall in early diastole
Left atrial collapse is highly sensitive for tamponade
A small, slit-like, hyperdynamic LV
Swinging to and fro of the heart within the pericardial fluid
IVC plethora (Dilation of the IVC and hepatic veins)
main echo finding in tamponade
left atrial collapse
how to treat a tamponade?
> drain pericardial fluid
ABCs
fluids: increase right sided filling pressures (Indicated in patients with signs of hypovolemia; May increase cardiac size and pericardial pressure and be harmful in euvolemic or hypervolemic patients
what should he avoided when treating tamponade?
Avoid PPV (positive pressure ventilation) – positive intrathoracic pressure will further decrease venous return and blood pressure – leads to impaired cardiac filling and worsen tamponade
when is pericardiocentesis indicated?
- hemodynamically unstable
- Tamponade
- Cancer patients to determine malignant vs. post-radiation vs. infectious pericarditis
- Failure to respond to treatment
- Suspected bacterial infection
when is a thoracotomy indicated?
Posttraumatic tamponade
Dissecting thoracic aorta aneurysm
Rupture of the myocardium
Pericardiocentesis is often unsuccessful in patients with haemorrhagic tamponade
pericardiocentesis complications
Dysrhythmia
Pneumothorax
Perforated myocardium
Coronary artery laceration
Mammary artery laceration
Liver laceration
