Pericardial window is used diagnostically and, more often, therapeutically for drainage of accumulated pericardial fluid (a condition that most often occurs after cardiac surgery but has many other possible causes). The pericardium envelops the heart like a cocoon; its cardiac filling can be impaired when this cavity fills with excess fluid. When the limited space between the noncompliant pericardium and heart is acutely filled with blood or fluid, cardiac compression and tamponade may result. Pericardial window in combination with systemic chemotherapy may also prevent accumulation of large fluid volumes in patients with neoplastic pericardial disease. [1, 2]
Pericardial window involves the excision of a portion of the pericardium, which allows the effusion to drain continuously into the peritoneum or chest.  The fluid can be drained in any of 3 ways: via a small subxiphoid incision, thoracoscopically,  or via a thoracotomy. 
The following are indications for a pericardial window  :
Symptomatic pericardial effusions
Asymptomatic pericardial effusions that warrant a pericardial window for diagnosis
Hemodynamically stable patients with an undiagnosed pericardial effusion (a thoracoscopic approach is ideal)
Coexisting pericardial, pleural, or pulmonary pathology that requires diagnosis or therapy (a thoracoscopic approach is ideal)
Known benign effusions that reaccumulate after aspiration
Drainage of a purulent pericardial effusion
Early fungal or tuberculous pericarditis in which resection of the pericardium is required to prevent future pericardial constriction
Use as part of the mediastinal debridement, in patients with descending mediastinitis
Loculated effusions situated unilaterally or posteriorly (more easily approached thoracoscopically)
Chylopericardium (thoracoscopic window and ligation of the thoracic duct)
Delayed hemopericardium or effusions after cardiac surgery (usually treated via a subxiphoid approach, but a thoracoscopic approach is also used)
An effusion in a patient with a substernal gastric or colonic conduit in whom a subxiphoid approach is not possible (an unusual indication for a thoracoscopic pericardial window)
The following is a contraindication for a pericardial window  :
Concomitant cardiac surgery necessitating a sternotomy for which a full pericardiotomy would be performed
The following technical points may improve the performance of pericardial window procedures:
If the patient is unstable, employ the subxiphoid approach
Use the Allis clamp to grasp the pericardium
Resect an adequate area of pericardium
Ensure that no undrained areas of the pericardial space remain by using a sucker to explore all areas
Equipment required for the subxiphoid and thoracotomy approaches includes standard thoracic instrumentation, along with the following:
Long curved Allis clamp
Aspirating needle used for mediastinoscopy
Endoscopic gastrointestinal anastomosis (GIA) stapler with vascular staple load
Peanut dissector and tonsil sponge
External defibrillator pads
Equipment required for the thoracoscopic approach includes all of the above, along with the following:
Patient preparation includes adequate anesthesia and proper positioning.
For the subxiphoid approach, general anesthesia is preferred and optimal. Arterial and central venous pressure monitoring may be needed intraoperatively, as well as in the postoperative period, to guide hemodynamic management. External defibrillator pads may be applied to the chest and back before preparation and may be connected to a defibrillator in case an arrhythmia develops during surgery.
For the thoracotomy and thoracoscopic approaches, general anesthesia with single-lung ventilation is required. As with the subxiphoid approach, arterial and central venous pressure monitoring may be needed, and external defibrillator pads may be used.
For the subxiphoid approach, the patient is placed in the supine position.
For the thoracotomy and thoracoscopic approaches, the patient is placed in a posterolateral or anterolateral thoracotomy position, depending on the approach and exposure of the pericardium. If doubt exists about the patient’s hemodynamic stability or ability to tolerate single-lung anesthesia, he or she can be placed supine and the side to be approached elevated with a pressure bag or jelly roll to allow access to that side. If the patient becomes unstable, a quick conversion to a subxiphoid window can be performed without repositioning. 
A short vertical incision (about 5-8 cm long) is made over the xiphoid, extending onto the midline of the abdomen (see the video below). The linea alba is incised, and the xiphoid is often completely removed. The retrosternal space is entered by means of finger dissection. With upward retraction, the diaphragmatic aspect of the pericardium is visualized.
The pericardium is grasped with the hook or an Adson or Allis clamp; alternatively, it may be incised directly. The opening in the pericardium is enlarged by sharply incising the pericardium. A sucker is inserted into the pericardial space and the fluid aspirated. Often, this sucker or a finger is used for further dissection of any adhesions.
A biopsy specimen is also taken from the pericardium. After all the fluid has been aspirated, the epicardium is inspected. A finger is introduced into the pericardial space to determine if any additional adhesions exist and if any nodules are in the pericardium. Finally, through a separate stab wound, a tube is inserted into the pericardial space and connected; the incision is closed in layers. 
A small anterior thoracotomy is made in the fourth or fifth intercostal space. An inframammary skin incision (6-8 cm long) allows division of the pectoralis muscle to expose the chosen intercostal space. The intercostal space is opened over the superior margin of the rib to allow entry into the pleural cavity. A retractor is placed, and the pericardium is visualized.
The pericardium is incised anterior to the phrenic nerve with a scalpel or scissors. A generous window is created, the pericardium is sent for pathologic inspection, and samples of the pleural effusion are obtained. The adjacent lung is palpated and a biopsy is easily performed if indicated. A chest tube is placed within the pericardium or the pleura and placed on water seal or suction. The incision is closed in layers. 
The thoracoscope is introduced in the seventh intercostal space in the midaxillary line or in line with the anterior superior iliac spine on the right (see the video below). On the left, the incision is placed just posterior to this line. The working incision is placed in the posterior axillary line in the fifth intercostal space or, alternatively, peristernally immediately above the pericardium. With the lung collapsed, the phrenic nerve is identified running vertically down along the pericardium; this nerve should be visualized throughout the operation.
On the left, the nerve runs through the middle of the lateral surface of the pericardium and should be sharply mobilized off the pericardium to allow tension-free retraction and wider access to the pericardial surface. Alternatively, the pericardium may be divided anterior and posterior to the phrenic nerve, so that it is left on an island of pericardium. This is done when a left-side pericardiectomy is to be performed.
On the right, the phrenic nerve is just anterior to the hilum of the lung and does not interfere with pericardial resection. If the posterior pericardium is to be incised, the pulmonary ligament is mobilized with an electrocautery after the lower lobe is grasped and retracted superiorly. This allows greater exposure of the pericardium and allows the lower lobe to be retracted out of the operative field.
If the posterior pericardial space is to be accessed, the posterior mediastinal pleura is opened from the level of the inferior pulmonary vein to the mainstem bronchus. On the right, the esophagus must be mobilized to improve the exposure. Blunt dissection with a tonsil sponge stick allows the pericardium to be separated from the surrounding soft tissue.
Alternatively, the anterior pericardium may incised, which makes these steps unnecessary. Often, the pericardium is distended or thickened, and the easiest approach is to grasp it with a long Allis clamp or ring forceps introduced through the working incision at a point anterior to where the initial incision is to be made, then retract it anteriorly or laterally to tent the pericardium. If the pericardium is too distended to allow this, the effusion is aspirated via a spinal needle introduced through the chest wall under thoracoscopic vision.
A scissors or electrocautery is used to open the pericardium. If the pericardium is very thickened or vascular, an endoscopic gastrointestinal anastomosis (GIA) vascular stapler can be used to extend the incision after the initial pericardial opening is made.
Adhesions between the heart and the pericardium may be dissected sharply with scissors or bluntly with a peanut dissector or Yankauer sucker, depending on the density or tenacity of the adhesion. The substernal plane can be dissected with an electrocautery across the midline or to the contralateral chest, depending on the size of the window to be created and on whether a pericardiectomy is to be performed. The opening in the pericardium should be a minimum of about 4 × 4 cm to ensure that the pericardial space will be adequately drained.
Once the window has been created, a Yankauer sucker is used to probe the pericardial space so as to ensure complete drainage of the effusion and break down fibrous septa that may prevent complete drainage. A 28-French chest tube or a No. 19 Blake drain is placed in the pericardiopleural or pleural space and brought out through the camera port incision. 
Pericardial effusions can be managed by means of either percutaneous pericardiocentesis or surgery. Pericardiocentesis is associated with high rates of early recurrence and, therefore, is used less often than pericardial window. 
In one series, the long-term results in 64 consecutive patients who underwent subxiphoid pericardial window over 11 years indicated that 18% of patients had a recurrence, with 50% of these requiring reoperation. Others observed an overall recurrence rate of 3.7% for pericardial effusion following pericardial window. In the literature, recurrence rates range from 0% to 33%.
Other complications include bleeding, infection, arrhythmia, myocardial infarction, cardiac arrest, and mortality.  Hemodynamic collapse following subxiphoid pericardial window has been reported,  as has a case of biventricular failure following pericardial window for a large pericardial effusion. 
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Dale K Mueller, MD Co-Medical Director of Thoracic Center of Excellence, Chairman, Department of Cardiovascular Medicine and Surgery, OSF Saint Francis Medical Center; Cardiovascular and Thoracic Surgeon, HeartCare Midwest, Ltd, A Subsidiary of OSF Saint Francis Medical Center; Section Chief, Department of Surgery, University of Illinois at Peoria College of Medicine
Dale K Mueller, MD is a member of the following medical societies: American College of Chest Physicians, American College of Surgeons, American Medical Association, Chicago Medical Society, Illinois State Medical Society, International Society for Heart and Lung Transplantation, Society of Thoracic Surgeons, Rush Surgical Society
Disclosure: Received consulting fee from Provation Medical for writing.
Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Nothing to disclose.
Richard A Lange, MD, MBA President, Texas Tech University Health Sciences Center, Dean, Paul L Foster School of Medicine
Disclosure: Nothing to disclose.
Eric H Yang, MD Associate Professor of Medicine, Director of Cardiac Catherization Laboratory and Interventional Cardiology, Mayo Clinic Arizona
Eric H Yang, MD is a member of the following medical societies: Alpha Omega Alpha
Disclosure: Nothing to disclose.
Medscape Drugs & Diseases thanks Dale K Mueller, MD, Clinical Associate Professor of Surgery, Section Chief, Department of Surgery, University of Illinois College of Medicine; Co-Medical Director, Thoracic Center of Excellence, Vice-Chair, Department of Cardiovascular Medicine and Surgery, OSF St Francis Medical Center; Director, Adult ECMO, Cardiovascular and Thoracic Surgeon, HeartCare Midwest, SC, for assistance with the video contribution to this article.
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