How to perform a pericardiocentesis
Pericardial effusion is a frequent sequela to the common pericardial diseases of small animals. Removing pericardial effusion is important from both a diagnostic and a therapeutic standpoint. When cardiac tamponade is diagnosed, pericardiocentesis should be performed as soon as possible.
With supplies and equipment found in most veterinary hospitals, performing a pericardiocentesis is actually quite simple. Even in cases in which referral to a cardiologist or other specialist is your ultimate goal, you may need to perform a pericardiocentesis to stabilize a patient first. Although the technique is similar to that of thoracocentesis, the anatomical margins are narrower, and certain complications are more likely. That being said, adhering to the following protocol will maximize the likelihood of success.
Equipment and staffingAn electrocardiograph with an oscilloscope is recommended but not required. If one is not available, it is important that someone is available to monitor cardiac rhythm throughout the procedure by palpating pulses. We also recommend placing an intravenous catheter to administer fluids and emergency drugs if needed.
The following equipment and staffing are needed to perform a pericardiocentesis:
Here we describe the technique for pericardiocentesis in dogs, but the same protocol is followed in cats by using smaller catheters.
You can perform this procedure from the right or left side of the thorax. It is easiest to perform with the patient in lateral recumbency to minimize motion. As mentioned earlier, if available, attach an electrocardiograph with an oscilloscope to the patient. If electrocardiography is not available, have an assistant monitor the cardiac rhythm by palpating the patient's pulse throughout the procedure. One assistant restrains the patient, and another helps you perform the procedure.
Pericardiocentesis can be performed using a right or left thorax approach because when marked pericardial effusion is present, pericardial distention pushes the lungs dorsally, resulting in a "cardiac notch" on the right and left side. The decision is based on your experience or if fluid accumulation is asymmetric (which rarely occurs). We prefer the left-sided approach for the following reasons:
1. It is easier to recognize iatrogenic puncture of the left ventricle than of the right ventricle. The oxygenated blood in the left ventricle is bright red. Both right ventricular blood and pleural effusion are dark red.
2. The high left ventricular pressure usually results in a pulsatile, high-velocity flashback into the catheter, making it obvious if you have penetrated the left ventricle.
3. The right ventricular wall is much thinner than the left ventricular wall, so it is easier to penetrate it unknowingly as you advance the needle and catheter.
Some practitioners, nonetheless, prefer approaching the pericardial sac from the right. Although we describe a left-sided approach here and in the photographs, a right-sided approach can be performed using the same landmarks. Many people prefer performing pericardiocentesis from the right side since there is a "cardiac notch" between the right cranial and caudal lung lobes where the risk of lung puncture is diminished. Furthermore, it is thought that there are fewer coronary vessels on the right side of the heart as it sits in the thoracic cavity. As there are major coronary and thoracic vessels on both sides of the thoracic cavity, whether a right-sided approach translates to a significant reduction in risk of side effects has not, to our knowledge, been documented.