Answer and Discussion
by Rob Leeper, MD, FRCSC
The subcostal 4 chamber view (SC4C) shows a massive pericardial effusion with signs of right atrial and ventricular collapse. Pressure effects on the right ventricle by this large effusion are further evidenced on the parasternal short axis (PSSAX) and apical 4 chamber (A4C) view. All of these findings are indicative of the physiology of cardiac tamponade. Ultimately, it was the patient’s shock state in conjunction with the pericardial effusion that confirmed this clinical diagnosis.
Although not all features are clearly present in this series of clips the principle echocardiographic signs of cardiac tamponade include1:
– presence of pericardial effusion
– diastolic collapse of right atrium +/- ventricle
– IVC dilatation and loss of respiratory variations
– respiratory increase of inter-ventricular dependence
– respiratory variations > 25% in mitral, aortic and/or tricuspid flow
The clinical syndrome of cardiac tamponade represents a medical emergency. In this patient, the cause was felt to be the sub-acute accumulation of malignant pericardial fluid related to his recurrent thoracic malignancy. The insidious nature of this type of neoplastic process has lead to it being coined “medical tamponade” to cast in in stark contrast to “surgical tamponade” resulting from rapid, acute accumulation of pericardial fluid, typically blood related to trauma, surgery, or catheter related interventions.
Treatment of tamponade can be divided between surgical and non-surgical interventions. Surgery has traditionally involved the creation of pericardial windows, pericardio-pleural fistulae, or formal pericardectomies2. However, with the notable exception of penetrating cardiac trauma, the past two decades have seen the standard of care for cardiac tamponade shifted to non-surgical techniques.
The foundational study on US guided pericardiocentesis was published out of the Mayo Clinic Rochester and includes data on over 1,000 patients spanning 21 years3. Several salient points merit discussion from this seminal work:
a) Success of US guided Pericardiocentesis – greater than 97% of all patients presenting with symptomatic effusions were able to achieve satisfactory drainage utilizing US guided techniques.
b) Complications – although dreaded complications do occur with this, as with any invasive procedure, the Mayo series reflects a 1.2% risk of major complications including cardiac perforation resulting in death or immediate cardiac surgical intervention, pneumothorax, and intercostal artery laceration. A further 3.5% of patients are subjected to minor morbidity such as transient chamber penetrations and supraventricular tachyarrhythmias.
c) Trends over time – the Mayo study divided the 21 year study period into thirds and showed a significant trend toward more overall procedures (181 vs 441) in the modern versus historical cohort. Additionally, more drains are being left in situ for chronic drainage (23 vs 75% of procedures) and as a result fewer patients are going on to require surgical intervention down the road (12% vs 3%). Finally, the indications for US guided drainage are shifting away from malignancy (41 vs 25%) and towards post operative and catheter related misadventure (4 vs 14%).
The technique of US guided Pericardiocentesis is not strictly defined or standardized. Windows for access include the subcostal, apical, and parasternal approaches. Real time/in line echocardiographic guidance of the needle is possible but challenging. A two person technique with one sonographer working from the apex while the other physician performs the procedure via a subcostal approach has also been described. In clinical practice this is often more of an “US informed” than truly ultrasound guided procedure.
A fairly accurate video tutorial on this technique is available online via the NEJM here. Fair warning that this video is ultra high resolution and adjustments to your screen settings may be required to optimize your viewing experience.
Regarding the performance of this procedure under US guidance, a few points merit discussion:
- Subcostal approach is by far the most common and often the easiest approach in the vast majority of patients. The location of needle entry should, however, be guided by the largest pocket of fluid (providing the greatest room for safety to avoid cardiac injury).
- The use of pericardial drains is likely pertinent in essentially all cases of tamponade. Recurrence rates without drains have been proved to be unacceptably high and risks for bacterial infection of the pericardial space have been traditionally overstated.
- The use of Agitated Saline to confirm location within the pericardial space is crucial prior to dilating the tract and inserting a formal Pericardiocentesis drain. Using a three way stop cock or simply by shaking up the first few cc’s of effluent and re administering it one can obtain an echocardiographic view of turbulent flow in the pericardial space which confirms location. Visualization of iatrogenically inserted bubbles in the LV cavity should inspire a reconsideration of the insertion angle as well as a switft communication with the CMPA (see videos posted below…)
Well performed pericardiocentesis
In this patient’s case an urgent call to cardiology was placed and an US guided pericardial drain was inserted with the immediate drainage of 1.3 litres of bloody, malignant appearing effusion. The patient’s blood pressure rose rapidly from 90 to 150 systolic over the first 30 seconds of drainage and his prior shortness of breath was entirely resolved.
Subcostal 4 chamber view after pericardiocentesis in our case:
2. Allen KB, Faber LP, Warren WH, Shaar CJ. Pericardial effusion: subxiphoid pericardiostomy versus percutaneous catheter drainage. Ann Thorac Surg. Feb 1999;67(2):437-40.
3. Tsang TS, Enriquez-Sarano M, Freeman WK, Barnes ME, Sinak LJ, Gersh BJ, Bailey KR, Seward JB. Consecutive 1127 therapeutic echocardiographically guided pericardiocenteses: clinical profile, practice patterns, and outcomes spanning 21 years. Mayo Clin Proc. 2002 May;77(5):429-36.