Cardiac tamponade: the compression of the cardiac cavities due to exerted pressure on the heart, by increasing the volume and pressure of pericardial fluid.
● as the fluid builds up, the pressure affects compliance created and it is sent transmurally to the cardiac wall, consequently increasing the interventricular pressure. This leads to decreased ventricular filling pressure and reduces the cardiac output by reducing the ejected volume.
● the compensatory mechanisms in case of cardiac tamponade are: increased peripheral resistance, increased central venous pressure and increased heart rate. All these mechanisms are designed to increase myocardial oxygen availability when the cardiac perfusion is limited.
● in some patients, paradoxical pulse and balancing pressures may be missing
● in patients with left ventricular diastolic pressure increased (as in chronic hypertension), the ventricular filling resistance is constant. During the cardiac cycle, balance between the pressures in these patients may be present only in the right heart cavities and the pressures in the left ventricle are higher than those of right ventricle.
● the absence of paradoxical pulse and hemodynamic signs not exclude classic tamponade.
Signs and symptoms of cardiac tamponade
● Beck’s triad – deafened heart sounds, hypotension, jugular venous distension
● The most common complaints are minimal effort intolerance and dyspnea. In advanced stages, agitation, CNS depression, coma and cardiac arrest may appear
● Decreased systolic arterial pressure
● Decreased pulse pressure
● Paradoxical pulse – more than 15mmHg decrease in systolic blood pressure between inspiration and expiration
● The veins of the neck may be distended and there is a rapid systolic slope and the attenuation or absence of the diastolic slope
● tachycardia – a compensatory mechanism to maintain cardiac output
● Sensitivity in upper right abdominal quadrant due to liver congestion
● Enlarged area of cardiac dullness beyond the area of the maximum apical pulse
Cardiac Tamponade Causes
● Neoplasm – breast cancer, lung, lymphoma, leukemia
● Post myocardial infarction (Dressler)
● Postoperative – up to 30% after pericardiotomy
● Symptomatic HIV Infection
● Other viral infections – Coxsackie B, influenza virus, echo, herpes
● Bacterial infections – S. aureus, M. tuberculosis, S. pneumonia (rarely)
● Fungal infections – M. capsulatum
● Lupus and rheumatologic diseases
● Placing a catheter to determine central venous pressure, pacemaker devices
Risk factors: cardiac tamponade should be suspected in hemodynamically unstable patient:
● With known pericarditis
● Non-penetrative or penetrating trauma to the chest
● Following open heart surgery or cardiac catheterization
● In the presence of known or suspected intrathoracic neoplasm
● When it is suspected a dissecting aneurysm of the aorta
● In the presence of renal failure treated through dialysis
Cardiac Tamponade Treatment – General measures
● Maintain hemodynamic stability to correct pericardial tamponade
● Monitoring of patients is mandatory – every 15 minutes to determine blood pressure, heart rate and at least a determination of CVP (central venous pressure). Special attention should be paid to the placement of a Swan-Ganz catheter if time permits
● Liquids can provide a temporary benefit, but increased filling pressures may additionally compromise the coronary perfusion
Treatment – Surgical steps
○ Directions – when hemodynamic function deteriorates rapidly, when the surgical procedure for effusion is delayed, or for diagnostic purposes
○ If rapid re-accumulation of fluid is anticipated (in malignant processes), the insertion of a catheter to drain on the long term may be helpful. You can also consider instillation of sclerosing agents.
○ The surgical procedure should be performed under the best possible conditions in relation to the patient’s condition
○ Blind pericardiocentesis should be performed only in case of life-threatening emergencies
○ Ideally, echocardiography should be performed at the bedside to assist needle placement and progression of fluid removal
○ invasive monitoring is also helpful to track the pericardial pressure
○ Fluoroscopy can be used
○ orientation using ECG through precordial leads in order to avoid contact with the epicardium may be useful
○ In 20% of patients with tamponade, the puncture is negative because the pericardial sac contains coagulated material. Hemorrhagic pericardial effusions generally do not coagulate.
Evolution / Prognosis: by applying appropriate treatment, the evolution is favorable.