*3.7.1 'Blind'*

In emergency situations at high risk of immediate patient demise, percutaneous pericardiocentesis may need to be performed 'blind'. In such cases, ECG monitoring and continuous needle aspiration during insertion should be utilised to confirm pericardial space entry. The commencement of fluid drainage from the inserted needle is suggestive of entry. However, a sanguineous aspirate may pose a dilemma for the clinician as it may be unclear whether this is due to a haemorrhagic pericardial effusion or myocardial puncture. The development of ST segment elevation on continuous ECG monitoring is suggestive of needle over-advancement leading to myocardial injury [19].

### **3.8 Echocardiography**

Since the development of echocardiography-guided pericardiocentesis in 1979, the technique has rapidly become standard of care [17]. The approach can either be performed under continuous echocardiographic surveillance, in which the needle tip is visualised throughout its trajectory from skin to pericardial space [20], or via the echocardiography assisted technique, in which the probe is used only to confirm entry into the space post insertion [17].

Regardless of approach subtype, correct position can be determined by injecting 5–10 mL of agitated saline through the needle and visualising bubbles arriving into the pericardial space. The presence of bubbles within the cardiac chambers is suggestive of needle over-advancement into the myocardium and should alert the clinician to withdraw. Inability to visualise bubbles can either be due to extra-cardiac position of the needle tip or presence of a very large pericardial effusion which hampers

visualisation. To distinguish between the two potential aetiologies more agitated saline should be injected and the pericardial space visualised from an alternative echocardiographic window.

#### **3.9 Fluoroscopy**

Fluoroscopy guided pericardiocentesis is performed in the catheterisation laboratory - most commonly for iatrogenic pericardial effusions that occur during interventional procedures or cardiac surgery [21, 22]. Injection of contrast through the needle tip followed by radiographic imaging can be used to assess needle tip position relative to the pericardial space. Should the position be correct, contrast will pool in the dependent portion of the pericardial space. Alternatively, a 0.035-inch J-wire can be inserted through the needle. It should be seen to curl around the heart silhouette on radiographic imaging if the needle tip is in the pericardial space. Guidewire position should be confirmed in two orthogonal planes (e.g., lateral and antero-posterior). Passage outside of this silhouette indicates an extra-pericardial location.

Fluoroscopy guidance is limited by radiation exposure to both patient and clinician along with the requirement to be performed in the catheterisation laboratory.

#### **3.10 Computed tomography (CT)**

In recent years computed tomography (CT) guided pericardiocentesis has emerged as a viable alternative technique for select indications such as cardiac effusions which are often posteriorly located and difficult to visualise with echocardiography [23]. The procedure involves a planning CT scan to delineate pericardial anatomy, subsequent needle insertion through the marked trajectory followed by a single CT scan post procedure to confirm needle entry. This technique is not performed under continuous CT imaging.

There are clear drawbacks to CT guided pericardiocentesis – lack of continuous imaging during insertion, radiation exposure and prolonged procedure time (median time is 65 minutes per procedure in one study [24]). However, despite these shortcomings, CT guidance does have clinical utility. It is particularly useful for cases of difficult-to-access loculated pericardial effusions or for access to 'dry' pericardial spaces (i.e., do not contain an effusion) for interventional procedures.

#### *3.10.1 Drainage catheter placement*

The drainage catheter is inserted via Seldinger-technique. A 0.035-inch J wire is inserted through the needle into the pericardial space. If resistance to insertion is encountered, the J-wire should not be forced. Instead troubleshooting should begin to identify the source of resistance. Once the J-wire is correctly and securely positioned, the insertion needle can be removed. A 6–8 Fr dilator is then inserted over the wire to dilate the entry tract for subsequent placement of the 6–8 Fr pigtail drainage catheter. Appropriate positioning of the drainage catheter can be proven via the various techniques outlined above.

The end of the 6–8 Fr pigtail drainage catheter is connected to a three-way tap so that pericardial fluid can be initially drained into a 50 mL Leur-lock syringe and subsequently transferred into the drainage bag. The drain is usually sutured to the skin to prevent dislodgement – particularly in cases of likely prolonged drainage time.
