Cardiac tamponade Flashcards
Describe the pericardium
- fibro-serous, fluid-filled sack
- surrounds heart + great vessels
- 2 layers –> Fibrous Pericardium (tough external layer) + Serous Pericardium (thin, inner layer)
- serous = 2 layers –> outer parietal layer(lines fibrous pericardium) + internal visceral layer (epicardium)
- between 2 layers serous layers = pericardial cavity= serous fluid
- normally 15-30ml fluid= reduces friction caused by heart contracting and moving around thoracic cavity
What is the pathophysiology of CT?
- fibrous pericardium- inextensible = problem if accumulation fluid in pericardial space= pericardial effusion
- rigidity= heart experiences raised pressure - chambers can become compressed- CO can decrease
- CT= pressure from intra-pericardial fluid accumulates causing compression of heart causing decreased cardiac output
- once you’ve reached pericardial compliance= P starts to increase ( first equalizes with RV diastolic P then Left ). CO decreases so contractility + rate increase to compensate
Describe the stages of CT
- Fluid filling recesses of 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
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.
What are the causes of CT?
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
what are the signs and symptoms of CT?
Symptoms
- Dyspnoea
- Chest pain, fullness, palpitations
- nausea, abdo pain,( hepatic + visceral congestion), anorexia
- dysphagia
- lethargy, weakness, fatigue( decreased CO)
- fever
- cough
Signs
- distended neck veins
- muffled heart sounds
- hypotension
- tachy
- pulses paradoxus
- absent apex beat
- tachpnoea
Which symptoms make up Becks triangle?
- Hypotension
- Diminished heart sounds
- JVD
Which symptoms make up Becks triangle?
- Hypotension
- Diminished heart sounds
- JVD
What is pulses paradoxus?
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
what are the differential diagnoses for CT?
- Massive PE
- T- PT
- SVC obstruction
- chronic constrictive pericarditis
- air embolism
- R infarct
- Severe CCF/ cardiogenic shock
- ## extra-pericardial compression: haematoma, tumour
what are the special investigations done for CT?
CXR
Cardiac silhouette may appear normal
At least 200-250 ml pericardial fluid is needed for cardiomegaly to be visible on CXR? - typical bottle shape
ECG
Sinus tachycardia
Decreased QRS voltage
Electrical alternans
Echo/ bedside ultrasonography
NB: clinically significant tamponade is a clinical diagnosis and echocardiographic signs of tamponade are not in itself an indication for acute intervention
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)
CT and MRI
Not suitable in the critically ill patient!!!!!!
Sensitive and specific for detecting pericardial effusion/ an alternative to echo
Treatment of CT?
Drainage of pericardial fluid
Initial medical management steps
Optimize oxygenation
Fluids to 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
Avoid PPV (positive pressure ventilation) – positive intrathoracic pressure will further decrease venous return and blood pressure – leads to impaired cardiac filling and worsen tamponade
what are the indications of a pericardiocentesis?
Haemodynamic compromise (pre-arrest) if patient too unstable to await pericardial window in operating room
Tamponade
Cancer patients to determine malignant vs. post-radiation vs. infectious pericarditis
Failure to respond to treatment
Suspected bacterial infection
How is a blind pericardiocentesis conducted?
The standard approach is subxiphoid, with you standing on the patient’s right.
Identify landmarks
After prepping and injecting some local anesthesia, identify the left xiphocostal angle, and slide down about 1 cm, no further than approximately 2 fingerbreadths.
This will be your entry point, 30 to 45˚ to the abdominal wall, aimed at the midpoint of the left clavicle. Aspirate as you advance the needle.
The heart is quite anterior, so any angle greater than 45 degrees is too much and makes you more likely to puncture the stomach or liver.
If your first advance fails to produce any fluid, withdraw the needle to just below the skin and redirect it a little more medially.
Watch cardiac monitor for a change in the QRS morphology, or ST elevation if the needle touches the myocardium
Aspirate fluid/blood
Consider placing a catheter/pigtail
Blood stained pericardial fluid will not clot whereas intraventricular blood will
How is the ultrasound guided pericardiocentesis conducted?
The most common ultrasound-guided approach is apical
Here, you’ll want to position yourself to the patient’s left.
Find the apex via palpation (or simply with the ultrasound)
Insert the needle approximately 1 cm lateral to this, with the point directed toward the patient’s right shoulder,
Use the same insertion-aspiration technique as above, visualizing the advance of your needle point with the ultrasound.
Make sure to advance over the cephalad portion of the rib inferior to your insertion point, avoiding the neurovascular bundle below the rib above.
Direct visualization is necessary for this approach, since the lingula lies very close to the apex, meaning that you have a high risk of causing a pneumothorax.
What are the complications of a pericardiocentesis?
-dysrhythmia
- pneumothorax
- perforated myocardium
- coronary artery laceration
- mammary artery laceration
- liver laceration
