Safety and utility of modified ultrafiltration in pediatric cardiac surgery

Introduction: Modified ultrafiltration (MUF) is employed at the termination of cardiopulmonary bypass (CPB) in pediatric and neonatal patients undergoing congenital heart surgery to reduce the accumulation of total body water thus increasing the concentration of red blood cells and the other formed elements in the circulation. Modified ultrafiltration has been reported to remove circulating pro-inflammatory mediators that result in systemic inflammatory response syndrome (SIRS) postoperatively. Methods: Four hundred patients undergoing cardiac surgery requiring cardiopulmonary bypass and weighing less than or equal to 12 kg were retrospectively evaluated for the effectiveness of MUF. After the termination of CPB, blood was withdrawn through the aortic cannula and passed through a hemoconcentrator attached to the blood cardioplegia set and returned to the patient through the venous cannula. The entire CPB circuit volume in addition to the patient’s circulating blood volume were concentrated until the hematocrit value displayed on the CDI cuvette within the MUF circuit reached 45% or there was no more volume to safely remove. At the same time a full unit of FFP can be infused as water is being removed, thus maintaining euvolemia. Results: MUF was performed in all 400 patients with no MUF-related complications. Following the conclusion of MUF, anecdotal observations included improved surgical hemostasis, improved hemodynamic parameters, decreased transfusion requirements, and decreased ventilator times. Conclusions: Complete MUF enables the clinician to safely raise the post-CPB hematocrit to at least 40% while potentially removing mediators that could result in SIRS. In addition a full unit of FFP can be administered while maintaining euvolemia.

Central Aortic Cannula Disruption Following Left Atrial Myxoma Excision

Background Central aortic cannulation is used to give oxygenated blood to the patient through a heart-lung machine. Major surgical intraoperative bleeding during cardiac surgery is a dreaded complication, resulting in significant morbidity and mortality. Central Aortic cannula disruption during Cardiopulmonary bypass (CPB) is a rare complication which needs prompt management. Case Presentation We are reporting a case of central aortic cannula disruption during LA myxoma excision in which the Metal tip part of the cannula detached from its body, resulting in massive blood loss. Intraoperative blood salvage technique was used to maintain hemodynamics during surgery.Conclusion Aortic cannula disruption is a rare complication and can be lethal to the patient, if not managed timely. Before cannulation, proper visual inspection of all cannulae by team members is very important to eliminate this type of complication.

Directing a dispersion cannula tip toward the aortic root during thoracic aortic arch surgery does not adversely affect cardiac function

Introduction: Neurologic complications of open thoracic aortic surgery are devastating problems in patients with severely diseased aortas. This study aimed to clarify whether directing the aortic cannula tip toward the aortic root affects the postoperative cardiac function in patients undergoing open thoracic aortic surgery. Methods: A total of 16 patients who underwent total or partial arch replacement between January 2014 and April 2019 were enrolled and divided into two groups. Ascending aorta perfusion was performed by placing the cannula tip toward the aortic root (reversed direction group, seven patients) or toward the aortic arch (standard direction group, nine patients). Intraoperative and perioperative data, including mortality, morbidity, and postoperative cardiac function, were compared between the groups. Results: There were no hospital deaths or stroke events in either group. The aortic cross-clamping time was 102.4 ± 20.3 minutes in the reversed direction group and 87.1 ± 9.9 minutes in the standard direction group (p = 0.049). Furthermore, the intubation time was 28.4 ± 12.9 hours in the reversed direction group and 12.4 ± 6.8 hours in the standard direction group (p = 0.022). Both times were significantly longer in the reverse direction group. Postoperative serum creatine kinase-MB levels were significantly lower in the reversed direction group (6.2 ± 3.3 U/L vs 13.3 ± 4.8 U/L, respectively, p = 0.006). The cardiac output and cardiac index did not significantly differ. Conclusions: Directing the aortic cannula tip toward the aortic root does not adversely affect the postoperative cardiac function after aortic arch surgery.

Development of a Custom Extracorporeal Circuit for Endovascular Resuscitation Research

Background: To demonstrate the utility and applicability of in vitro extracorporeal circuits in endovascular resuscitation research. Methods: The method for building an inexpensive in vitro extracorporeal circuit for endovascular resuscitation research is described. In this study, aortic cannulas and pump combinations were evaluated in the in vitro extracorporeal circuit. Then one aortic cannula and pump set up was evaluated in a post-mortem swine model. Flow data was collected and compared among groups. Results: The peristaltic pump generated the highest flow as compared to the other pump combinations at any given catheter size. The peristaltic pump combined with the 10 Fr cannula produced the highest flow overall at 2304 mL/min. This same combination produced a peak flow of 886 ml/min at the aortic root in the swine model. Conclusions: The flow generated in the swine model was less than half of that generated in the in vitro model. However, all flow was channeled through one outflow tract in the in vitro model whereas the swine aorta has several branches of outflow. As such, a 50% reduction in flow or greater is anticipated at the level of the aortic root. An in vitro extracorporeal circuit for endovascular research can be built for less than $10,000, with most of the materials being reusable, and can be used to generate representative data that may be anticipated in a swine model.

Aortic Cannulation around Grade 5 Aortic Arch Atheroma Utilizing Transesophageal Echocardiography

A 61-year-old male with severe aortic valve stenosis was scheduled for a minimally invasive bioprosthetic aortic valve replacement. Intraoperative transesophageal echocardiography (TEE) showed a unicuspid aortic valve and extensive aortic atheromatous disease. A large atheroma with mobile components existed near the distal aortic arch. A 17-French aortic cannula was successfully placed using TEE guidance with the tip proximal to the mobile atheroma to avoid inadvertent disruption and subsequent embolic sequelae. The patient had no evidence of perioperative stroke or other complications postoperatively. This case demonstrates one strategy to manage severe atheromatous disease intraoperatively. We also review additional management options.

Clinical evaluation of a new dispersive aortic cannula

Introduction: Cerebral injury is a serious complication in open-heart surgery. Once it occurs, it causes significant disability and death. We developed a novel dispersive aortic cannula named the Stealth Flow cannula and used it as a standard aortic cannula in cardiopulmonary bypass. The aim of this study was to evaluate the efficiency of this aortic cannula. Methods: A total of 182 consecutive patients undergoing cardiac surgery using cardiopulmonary bypass were studied. The patients were divided into two groups: the Soft-Flow cannula group (n = 89) and the Stealth Flow cannula group (n = 93). Patients with a shaggy aortic arch were excluded from this study because the cannulae were inserted at the ascending aorta with a cannula tip directed toward the aortic root in these cases. Patients with multiple arterial perfusion sites were also excluded. Complications including early mortality, perioperative stroke, and intraoperative aortic injury were compared between the two groups. Results: Age, operative procedure, cardiopulmonary bypass time, and the Japan SCORE were not significantly different between the groups. In comparisons between the Stealth Flow and Soft-Flow groups, the incidences of early mortality, perioperative stroke, intraoperative aortic dissection, and all complications were 1.08% versus 1.12% (p = 0.98), 1.1% versus 2.2% (p = 0.53), 0% versus 1.1% (p = 0.33), and 1.1% versus 3.4% (p = 0.29), respectively. The incidence of major cardiovascular events, including early death, perioperative stroke, and aortic dissection, was not different. Conclusions: The Stealth Flow cannula, which was designed based on our previous experimental study, contributed to reducing cerebral and aortic events as much as the Soft-Flow cannula in the present clinical study.