Pericardiocentesis – A Review

Deena Relucio, DVM, summarizes how to recognize a patient in need of pericardiocentesis and the technical approach to the procedure.

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Pericardiocentesis is a potentially life-saving therapeutic procedure commonly performed on the ER floor. Although considered relatively safe, this invasive procedure may be associated with serious complications. If left untreated, increased intrapericardial pressure can lead to compression of the atria and ventricles (cardiac tamponade) resulting in decreased cardiac output and hemodynamic compromise to the patient.  Pericardiocentesis is often an emergent procedure and it is essential to efficiently and effectively communicate the suspected diagnosis, prognosis and goals of the pericardiocentesis to the client. In addition, it is important to prepare them for the potential complications, the immediate costs associated with the procedure, and financial investment ahead.  This review aims to summarize how to recognize a patient in need of pericardiocentesis and the technical approach to the procedure.

 

CLINICAL FINDINGS

A typical history may be reported as acute collapse, exercise intolerance and weakness. Patients may present in cardiac arrest or already deceased with a client-reported history of peracute onset of clinical signs. The physical exam may reveal a prolonged capillary refill time, pale mucous membranes, muffled heart sounds, tachycardia, tachypnea, dyspnea, weak pulses or pulses paradoxus (weaker pulse during inspiration with cardiac tamponade), jugular distention or abdominal distention (cranial organomegaly, ascites). Only a few of these may be present on physical exam.

 

DIAGNOSTICS

A brief ultrasound scan provides definitive diagnosis for pericardial effusion. A minimum of 15ml of fluid is required to visualize on ultrasound. Sonographically, pericardial effusion appears as a hyperechoic pericardium surrounding an anechoic rim of fluid, which is normally evenly distributed around the heart. Diagnosis can be complicated by the presence of pleural effusion as in some cases of large volumes of pleural effusion can mimic pericardial effusion. It can be helpful to look for an anechoic effusion surrounding the “floating” auricular appendage, which is indicative of fluid around the pericardium. 

On ECG, there may be sinus tachycardia, ventricular premature complexes, ventricular tachycardia, or electrical alternans (alternating variation in the amplitude of QRS complexes with every other beat as the heart swings inside a voluminous pericardial sac).

Thoracic radiographs will be distinct and demonstrate a globoid cardiac silhouette with well-defined margins and distended caudal vena cava on all views. The films may also show pleural effusion and ascites in the cranial abdomen. If only a small amount of pericardial effusion is present, it may be difficult to differentiate pericardial effusion with various other cardiovascular diseases on radiographs alone.  However, radiography is an important tool if your practice does not have ultrasound capabilities. The films can be used as a guide for the proposed pericardiocentesis site. On the VD/DV view take notice which rib space has the most contact with the cardiac silhouette. A post procedural radiograph may be helpful in identifying underlying pathology (pulmonary nodules, mediastinal mass), or pneumothorax once the majority of the fluid has been removed. 

Bloodwork that includes complete blood count and chemistries may be non-specific, but may show anemia, hypoproteinemia, leukocytosis, possible liver enzyme elevation, or azotemia. If time allows, a coagulation profile may be performed to check PT/aPTT in-house. This can be valuable information prior to pericardiocentesis.

Considerations: Physical and diagnostic findings will be dependent on volume of pericardial effusion, speed of accumulation, and underlying pathology. The severity of intrapericardial pressure is greater with acute and large volumes of fluid. In chronic cases, the pericardium can stretch to accommodate even large volumes without decompensating. If the patient is relatively stable and has minimal pericardial effusion based on diagnostics, it will be beneficial to have an echocardiogram performed by a cardiologist or trained sonographer as a small quantity of pericardial fluid allows for greater visualization of auricular masses. This can provide valuable prognostic information for the owner.

 

PREPARING YOUR PATIENT and SETUP

Place an IV catheter in the event that emergency medications need to be administered. ECG leads should be placed to monitor and track cardiac activity during and after the pericardial tap. If possible, 2-3 people should be recruited for the procedure - the clinician that performs the actual tap, an assistant that restrains the patient, and another assistant that controls the suction under the direction of the clinician.

 

EQUIPMENT

  • Sterile prep – clippers, scrub, sterile gloves
  • IV catheter, depending on size of patient
    • 18-14 g peripheral IV catheter or abbocath catheters for larger or obese dogs
  • 3 – way stopcock
  • Extension set
  • Syringe – 20, 35, or 60 ml
  • Collection bowl
  • Red top tube and lavender top tube

 

ANALGESICS and EMERGENCY DRUGS

The majority of patients may be very weak and will be more receptive to handling. If necessary a light sedation may be given such as butorphanol (0.1-0.3 mg/kg). Lidocaine may be used as a local anesthetic at the proposed site at 0.5-1ml/site into the subcutaneous space and intercostal muscle layers. Anesthetize the proposed site cranial to the rib, avoiding the neuromuscular bundle and vessels caudal to the rib. Be prepared to intubate in case of cardiac arrest.

  • Lidocaine should be drawn and ready in the event of ventricular tachycardia
    • 2mg/kg (dogs), 0.25-0.5 mg/kg (cats)
  • Epinephrine: high dose (0.1 – 0.2 mg/kg) and low dose (0.01 – 0.02 mg/kg) IV

 

PROCEDURE

The patient can be placed in either sternal or left lateral recumbency depending on patient stability and comfort. Oxygen supplementation should be provided. The right hemithorax is the preferred site as this approach lessens the chance of coronary artery laceration. Additionally, the cardiac notch is larger on the right lung lobes, which reduces accidental puncture of lung parenchyma.  This procedure is not without risk. However, theoretically it is possible to puncture the thin-walled right ventricle with this approach. The deoxygenated blood can have the same port wine color as typical pericardial effusion but the clinician will generally feel movement or “bounce” through the needle and the ECG will reveal disturbances in cardiac activity so it is unlikely to go unnoticed.

Clip and surgically scrub the proposed site from the 2nd to the 7th intercostal space (ICS) from the sternum to the mid-thorax. Some clinicians prefer fenestrating the catheter to allow for better drainage however this may compromise the integrity of the catheter and increase the risk for breakage while inside the pericardium. If desired, two to three small 1-2 mm fenestrations at the distal end of the catheter can be made with a #11 blade while the needle is still in place. Do not burr the catheter or allow the fenestrations to exceed 40% of the diameter of the catheter. In veterinary medicine, pericardiocentesis is often performed blindly once the projected site is established via ultrasound. Use radiographs to determine the point at which the cardiac silhouette is closest to the body wall if ultrasound is not available. While monitoring the ECG, palpate for the point of maximum intensity (PMI), typically at ICS-5. Insert the catheter perpendicularly at the locally anesthetized site cranial to the rib and apply light suction. A light pop may be felt once the pleural space is entered. Fluid may be obtained if pleural effusion is present. While monitoring the ECG, slowly advance the catheter further until the needle encounters the pericardial sac. Some clinicians report feeling a “scratching” sensation, then advance another 3-4 mm until pericardial fluid is obtained. The stylet can be removed once the correct location is achieved. Hold the catheter steady, and then connect to an extension set, 3-way stopcock and syringe. The assistant can control the syringe and suction under the guidance of the clinician. It will be important to communicate if any complications are encountered, as the majority of the adverse events occur during the active pericardial tap.  Slight adjustments in catheter positioning can be made if the patient develops arrhythmias or negative pressure is encountered. Progress may be checked intermittently with ultrasound. Withdraw the catheter under light suction once negative pressure is obtained or if only a small amount of fluid remains. It will not be possible to remove all pericardial fluid. In most cases the puncture left behind into the pericardial sac will continue to leak out into the larger pleural space. The patient’s vital signs usually improve rapidly and dramatically due to the decreased intrapericardial pressure and increased cardiac output. Compare the aspirated effusion with peripheral blood PCV and total protein. Generally speaking, if the blood does not clot, it is likely effusion. Blood may also not clot in cases of actively bleeding tumors, atrial tears, and coagulopathy. If the fluid removed clots in 1-2 minutes, it is suspicious for ventricular blood. Effusion generally has a lower PCV than peripheral blood with xanthrochromic (yellow) supernatant once spun down. Pericardial fluid can be submitted for cytologic analysis (+/- culture), but it is typically not highly diagnostic for the cause of the effusion.

Considerations:

Cats are at higher risk for complications during pericardiocentesis due to size and smaller volumes of effusion. Most respond well to medical therapy as pericardial effusion is often associated with congestive heart failure. This procedure is generally reserved for patients with severe tamponade and who are quite hemodynamically unstable. A smaller peripheral or butterfly catheter may be used in lieu of a larger gauge catheter if attempted. All the same preparations apply, but almost all cats will require more tranquilization for this procedure than dogs.

 

COMPLICATIONS

Statistically, pericardiocentesis carries a low rate of complication in the canine patient.  It is important to classify between procedural complications from progression or effects of underlying disease.  In most cases, it may not be possible to distinguish the difference. Most complications associated with pericardiocentesis occur during or shortly after the procedure (<1 hour). Arrhythmias are the most common and may be attributable with underlying disease, needle contact with the epicardium or reperfusion syndrome. Ventricular tachycardia will often require lidocaine therapy. Other less common complications include hemorrhage, pneumonthorax, and cardiac arrest. Ideally, the patient should be monitored the next 24 hours for cardiac arrhythmias and serial ultrasound scans to check for refilling of the pericardium. Requirement for a second pericardiocentesis within a short window is a poor prognostic indicator but may be necessary if cardiac tamponade recurs.

 

PROGNOSIS

Prognosis is generally poor to guarded depending on underlying cause. (Table 1). The majority of pericardial effusion seen in the emergency setting is often attributed to neoplasia in the dog.

Table 1:

Type of Pericardial Effusion

Differential Diagnosis

Key features

Hemorrhagic

Heart based tumors

Right atrial Hemangiosarcoma

Metastatic Neoplasia (lymphoma)

Idiopathic

Trauma

Left atrial rupture

Older brachycephalic breed dogs

Non clotting blood

Older large breed dogs

Middle aged, large breed

 

Older dogs with valvular disesae

Transudate

Coagulopathy (rodenticide, other)

Congestive heart failure

Hypoproteinemia

Sequela after repair of PPDH

 

Exudate

Infectious pericarditis

 

Suppurative pericarditis

Coccidioidomycosis, Actinomyces, Nocardia

Foreign body, Hematogenous

CONCLUSION

When performed correctly, pericardiocentesis can be a relatively safe procedure that carries a low rate of complication and provides valuable prognostic information for the client. Effective and efficient communication with client regarding the pet’s condition as well as the cost and potential risks of pericardiocentesis are key in gaining owner consent for this potentially life-saving intervention.  Quickly identifying a patient in cardiac tamponade and providing potentially life saving treatment is crucial. A good understanding of the pericardiocentesis procedure and anticipating complications can increase clinician preparedness and satisfactory outcomes in this often-emergent situation.

 

REFERENCES

1. Beardow, A. The Diagnostic and Therapeutic Approach to the Patient in Acute Congestive Heart Failure. Clinical Techniques in SmallAmmal Practice, Vol 15, No 2 (May), 2000. pp 70-75

2. Gildlewski, J & Petrie, JP. Pericardiocentesis and Principles of Echocardiographic Imaging in the Patient with Cardiac Neoplasia. Clinical Techniques in Small Animal Practice, Vol 18, No 2 (May), 2003: pp 31-134

3. Humm, K, et al. Adverse events associated with pericardiocentesis in dogs: 85 cases (1999-2006) . Journal of Veterinary Emergency and Critical Care 19(4) 2009, pp 352–356

4. Scansen, B. Interventional cardiology for the criticalist. Journal of Veterinary Emergency and Critical Care 21(2) 2011, pp 123–136

5. Silverstein, D & Hopper, K. Small Animal Critical Care, 2e. 2014

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