Feasibility and early outcomes of robotic-assisted pericardial window creation

Introduction

Background

Pericardial effusion is defined as an accumulation of greater than 50 milliliters of fluid in the pericardial sac (1,2). Clinical presentation varies depending on the rate and volume of fluid accumulation, leading to variable hemodynamic impacts (3). Pericardial effusion is a common clinical finding, with studies reporting a prevalence of 3–9% of patients undergoing echocardiography and approximately 20% of high-risk emergency department cases (4). The condition can arise from a wide range of etiologies, generally classified into inflammatory versus non-inflammatory (3). Most cases of pericardial effusions are idiopathic, with the remaining cases typically stemming from infection, malignancy, and autoimmune processes. If left untreated, pericardial effusion can progress to cardiac tamponade and hemodynamic collapse. To determine the most appropriate treatment option, it is essential to evaluate clinical symptoms, hemodynamic status, echocardiographic findings, response to treatment of the underlying cause, and the necessity for concurrent procedural intervention (5).

Various surgical techniques have historically been employed for pericardial window creation. The most common open approach employs a subxiphoid incision to access the pericardium without requiring the traditional sternotomy or thoracotomy incision. The subxiphoid approach is limited by the resultant difficulty visualizing cardiac structures located above the apex, as well as the potential for late constriction (6-9). The first minimally invasive technique employed for pericardial window creation utilized video-assisted thoracoscopic surgery (VATS). This approach offers several advantages over the traditional, more invasive approaches, including reduced incisional morbidity, enhanced visualization of intrapericardial structures, opportunity to drain pericardial fluid into the pleural space, and the ability to perform intrathoracic tissue sampling or biopsies, which is particularly important in cases with suspected malignant etiology (10,11).

Rationale and knowledge gap

The introduction of robotic-assisted thoracoscopic surgery (RATS) has contributed to substantial advancements in the field of cardiothoracic surgery. While the adoption of the robotic platform in cardiac surgery has trailed general thoracic surgery over the last two decades, utilization in cardiac procedures has been steadily increasing (6,12-16). While VATS is an effective procedure with favorable results, the platform is limited by decreased dexterity with thoracoscopic instruments (10,17). Benefits of the robotic platform include enhanced dexterity and visualization, increased precision, shorter hospital length of stay (LOS), and reduced incidence of postoperative cardiac complications (12,18-20). The existing literature detailing RATS utilization for pericardial disease describes pericardiectomy in the setting of chronic pericarditis (17,21). However, outcomes of robotic-assisted pericardial window creation have not been robustly reported.

Objective

We aimed to examine and report our institutional experience and associated outcomes of robotic-assisted pericardial window creation and present this article in accordance with the STROBE reporting checklist (available at https://asj.amegroups.com/article/view/10.21037/asj-25-43/rc).

Methods

We performed a single-center, retrospective review of patients of 18 years of age or older who underwent robotic-assisted pericardial window creation between September 2020 and March 2024. All patients included in the analysis had undergone a preoperative echocardiogram to assess the size and characteristics of the effusion, underlying cardiac function, and signs of impending tamponade. Effusion size was defined using Weitzman’s criteria with large (>20 mm echo-free pericardial space), moderate (10–20 mm), or small (<10 mm) effusions classified based on end-diastolic echocardiography (22,23). Preoperative pericardiocentesis was performed at the discretion of the multidisciplinary treatment team. All operations were carried out under general anesthesia utilizing single-lung ventilation by a surgeon experienced with the robotic platform, having performed greater than 1,000 prior robotic cases throughout their career. The presence of a concomitant intervenable pathology, such as significant pleural effusion in a specific hemithorax, dictated the surgical approach from the ipsilateral side; otherwise, the choice of laterality was determined by surgeon preference.

The da Vinci Xi Robotic Surgical System (Intuitive Surgical, Inc., Sunnyvale, CA, USA) was employed. Patients were intubated with double-lumen endotracheal tubes and positioned in either the right (n=14) or left (n=8) lateral decubitus position. An 8 mm trocar was placed in the 7th or 8th intercostal space near the midaxillary line for intrathoracic visualization to guide remaining port placement. Moving posteriorly, two additional 8 mm ports were then placed at the approximate levels of the 7th or 8th intercostal levels, spaced approximately 9 cm apart to appropriately target the pericardium. When performing a left-sided approach, an additional 8 mm port was placed approximately 10 cm further posteriorly in the 7th or 8th intercostal space to facilitate retraction of the lingula for adequate exposure. A 12 mm AirSeal access port (AirSeal^®, ConMed, Utica, NY, USA) was then placed approximately two intercostal spaces below the above working ports and between the two most anterior superiorly placed ports to serve as an access port for the bedside assistant. Port placement was typically performed in a similar configuration to that utilized for a classic complete portal robotic lobectomy with four arms (CPRL-4) (24). Typical port placement for this procedure is highlighted in Figure 1. Upon entry into the chest, the thoracic cavity was inspected, and adhesions to the pericardium were carefully lysed using electrocautery. After exposure of the pericardium, the phrenic nerve was identified, and a pericardiotomy was created posterior and parallel to its location (Video 1). If the effusion etiology was unknown, pericardial fluid was collected for gram stain, culture, and cytologic analysis. The window was enlarged to two to three centimeters using bipolar electrocautery or scissors, and the portion of involved pericardium was excised and processed for histologic review. Loculations were disrupted using gentle blunt dissection, and accessible fibrinous debris was removed (Video 1). The robotic suction irrigator was used for drainage of the pericardial fluid and removal of debris. Indicated concomitant procedures were performed, and a 24-French Blake tube thoracostomy was placed and immediately connected to the water seal. The lung was reinflated, and the patients were extubated and transferred to the recovery room. Removal of thoracostomy tubes was planned for post-operative day one following chest X-ray (CXR) demonstrating absence of significant pneumothorax and confirmation of minimal drainage from the tube.

Figure 1 Schematic for robotic pericardial window port placement. The superior working and camera ports are placed in the 7th or 8th intercostal spaces, and the inferior access port is placed approximately two intercostal spaces inferiorly. The dashed line denotes the midaxillary line. Camera port represented by the “x” symbol. Additional working ports used for both right- and left-sided approaches are represented by solid circles. Additional posterior working port utilized for left-sided approach represented by hollow circle. Access port represented by a star symbol. This schematic was created using an open-access background image from TogoTV, licensed under the Creative Commons Attribution 4.0 International License (© 2016 DBCLS TogoTV, CC-BY-4.0 https://creativecommons.org/licenses/by/4.0/), and has been adapted with markings to indicate port placement. The source permits reuse and adaptations and does not require additional permissions.

At two-week postoperative follow-up, patients underwent echocardiography to evaluate for recurrent or residual pericardial effusion. The primary outcome was resolution of pericardial effusion with absence of detectable pericardial fluid on echocardiogram. Secondary outcomes investigated included operative duration, as defined as time elapsed from skin incision to skin closure, need for platform conversion, intraoperative bleeding requiring transfusion, intraoperative damage to surrounding structures, intraoperative hemodynamic instability, hospital LOS, and post-operative complications, including arrhythmia, bleeding requiring transfusion, development of pleural effusion or pneumothorax, surgical site infection, 90-day readmission, 90-day reintervention, and mortality prior to discharge. Data were collected through a systematic chart review.

Statistical analysis

Descriptive statistics were employed via Microsoft Excel version 2024 (Microsoft, Redmond, WA, USA), with categorical variables presented as frequencies (percentages) and continuous variables reported as mean ± standard deviations or medians [interquartile range (IQR)] based on assessment of data normality.

Ethical considerations

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Medical College of Wisconsin Institutional Review Board #5 (PRO00048940), and individual consent for this retrospective analysis was waived.

Results

Twenty-two patients met the inclusion criteria for the study. Of these patients, 10 (45.5%) were male with a median age of 66.5 years (IQR 58.5–77 years) and a mean BMI of 28.7±6.2 kg/m² (Table 1). Fourteen (63.6%) patients in the study cohort had undergone prior pericardiocentesis before operative intervention. Effusion etiologies included idiopathic (31.8%), autoimmune (27.3%), malignant (18.2%), secondary to congestive heart failure (CHF) (9.1%), infectious (4.5%), graft versus host disease (GVHD) (4.5%), or renal failure (4.5%) (Table 1). Preoperative echocardiogram indicated signs of impending tamponade in seven patients (31.8%) as evidenced by diastolic ventricular or atrial compression and high respiratory phasic variation in flow velocities; however, all patients were able to safely undergo operative intervention without development of tamponade. Based on end-diastolic echocardiography, 17 patients were found to have large effusions (>20 mm), four patients had moderate effusions (10–20 mm), and one patient had a small effusion (<10 mm). All patients were hemodynamically stable at the start of operative intervention following induction of general anesthesia.

Intraoperative and postoperative outcomes are summarized in Table 2. Based on preoperative indication for procedure, four patients (18.2%) underwent concomitant procedures at the time of pericardial window, including left atrial appendage exclusion, tunneled pleural catheter placement, pulmonary wedge resection, and percutaneous endoscopic gastrostomy tube placement. The average procedure duration was 54.7±17.8 minutes for patients undergoing isolated pericardial window and 60.3±17.0 minutes for patients undergoing pericardial window with an additional procedure. A left-sided approach was utilized in 14 cases, while the remaining 8 cases were via a right-sided approach. Notably, none of the procedures required conversion to an open operation, and no patients developed intraoperative hemodynamic collapse, intraoperative or post-operative bleeding requiring transfusion, or post-operative arrhythmia. The median LOS was 6 days (IQR 4–8 days). Postoperatively, 3 patients developed ipsilateral pleural effusions requiring drainage. Six patients were readmitted within 90 days secondary to heart failure exacerbation (n=3), gastrointestinal bleeding (n=1), recurrent pericardial effusion requiring reoperation (n=1), and injuries related to motor vehicle collision (n=1). The one patient who required reoperation had effusion secondary to bacterial pericarditis (Streptococcus constellatus) and required creation of an additional window on the right side of the pericardium due to loculations that were not accessible during the initial left-sided approach. No patients developed post-operative surgical site infections. All patients survived to hospital discharge. Two-week post-operative echocardiogram was performed for 21 of the 22 patients and revealed no detectable or trace pericardial effusion in 14 patients, residual small effusion in five patients, and residual moderate effusion in two patients. Twenty of the 22 patients (90.9%) had improvement in effusion on post-operative echocardiogram in comparison to pre-operative echocardiogram, as defined by reduction by at least one predefined effusion size category. Of the 7 patients with detectable effusions greater than trace in size, four patients’ effusions decreased in size from large to small, one effusion decreased in size from moderate to small, one patient had a persistent moderate effusion, and one patient had a persistent small effusion. For the one patient who did not undergo a two-week post-operative echocardiogram, an echocardiogram performed three months post-operatively revealed trace effusion.

Discussion

Pericardial effusions have varying degrees of clinical significance, requiring a range of treatment modalities (3). While pericardial effusion can result from a variety of etiologies, including malignancy, autoimmune disease, renal disease, or infection, 40–85% of cases are idiopathic (23,25). When medical management of pericardial effusion is ineffective, surgical intervention may be indicated. Traditional surgical approaches include open procedures via subxiphoid or thoracotomy incisions (6,8). However, with a rise in the prevalence of minimally invasive approaches to complex pathologies, ongoing investigation of the benefits of minimally invasive platforms is essential. Though video-assisted pericardial window has been shown to be an effective procedure with low operative morbidity, the utility of robotic-assisted pericardial window has not been robustly described. In this study, we report short-term outcomes for 22 patients who underwent robotic-assisted pericardial window creation at our institution. Of these patients, 15 patients (68.1%) demonstrated complete or near-complete resolution of effusion on post-operative echocardiogram. Postoperatively, one patient required reoperation for concomitant recurrent pericardial effusion.

The study cohort consisted of medically complex patients with multiple comorbidities and several patients of advanced age. Prior reviews of pericardial window procedures typically report a mean patient age of over 50 years old with multiple comorbidities and a similarly diverse range of effusion etiologies (10,11,26-28). According to the prospective study performed by Muhammad et al., patients undergoing video-assisted pericardial window creation at their institution had a mean LOS of 10.2±12.1 days with a mean operative duration of 111.3±30.7 minutes (11). Similarly, Georghiou et al. reported an average LOS of 6.4 days and a mean operative duration of 46 minutes for management of pericardial effusion via VATS (10). We report an average LOS of 8.6 days and a mean operative time of 55.7 minutes in our small patient cohort undergoing robotic-assisted pericardial window creation, outcomes that are comparable to those reported for the VATS approach.

While VATS-specific pericardial window creation readmission rates have not been reported, a study utilizing the 2016–2019 Nationwide Readmissions Database utilized to compared outcomes of pericardiocentesis and surgical pericardial effusion drainage, reporting a 30-day non-elective readmission rate of 20.1% for all surgical drainage procedures (29). Further, reintervention rates after surgical window creation reportedly range from 0 to 33% (27,28,30,31). We report a readmission rate of 27% and reintervention rate of 4.5% in our small patient cohort, with the previously described patient who required readmission and reoperation having cultures positive for Streptococcus constellatus and developing loculations related to endocarditis. Thus, it is difficult to discern if effusion recurrence was related to initial incomplete drainage of inaccessible loculations or ongoing endocarditis contributing to reaccumulation of fluid. Despite this, our reported reintervention rate is comparable to those reported in existing literature.

In regard to operative technique, the robotic platform offers greater intraoperative dexterity and visualization of the thoracic cavity while facilitating the performance of necessary concomitant procedures (13). Similar to a VATS approach, RATS requires single lung ventilation to allow for sufficient exposure in the thoracic cavity and therefore requires careful patient selection for platform use. Given this, a robotic-assisted approach to pericardial window may not always be feasible, particularly in patients with effusions causing hemodynamic instability secondary to cardiac tamponade.

This study is limited by its retrospective nature as well as its review of a small patient cohort at a single institution with short-term postoperative follow-up data. Further investigation of robotic-assisted pericardial window is warranted to assess long-term and patient-reported outcomes. Additionally, in order to better elicit patient characteristics independently associated with worse outcomes, as well as the outcome differences for video-assisted and robotic-assisted approaches to pericardial window creation specifically, future studies with matched comparison groups in larger patient cohorts may be helpful to identify which patients would be best suited for the robotic approach.

Conclusions

Our findings suggest that robotic-assisted pericardial window creation is a safe and effective procedure for the management of pericardial effusion when performed by experienced surgeons at well-equipped institutions. The enhanced dexterity and improved visualization of the pericardium and thoracic cavity provided by the robotic platform may enable patients with complex anatomy to undergo the operation while facilitating the ability to complete concomitant operations simultaneously. Future comparative studies will be valuable in further exploring the advantages of the robotic-assisted approach for pericardial window procedures.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://asj.amegroups.com/article/view/10.21037/asj-25-43/rc

Data Sharing Statement: Available at https://asj.amegroups.com/article/view/10.21037/asj-25-43/dss

Peer Review File: Available at https://asj.amegroups.com/article/view/10.21037/asj-25-43/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://asj.amegroups.com/article/view/10.21037/asj-25-43/coif). P.L.L. serves as an unpaid editorial board member of AME Surgical Journal from November 2024 to December 2026. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Medical College of Wisconsin Institutional Review Board #5 (PRO00048940) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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