Vacuum assisted cardiopulmonary bypass in minimally invasive cardiac surgery: its feasibility and effects on hemolysis

Single-Center Experience With a Self-Expandable Venous Cannula During Minimally Invasive Cardiac Surgery

OBJECTIVE

Venous drainage is often problematic in minimally invasive cardiac surgery (MICS). Here, we describe our experience with a self-expandable stent cannula designed to optimize venous drainage.

METHODS

The smart canula^® was used in 58 consecutive patients undergoing MICS for mitral valve disease (n = 40), left atrial myxoma (n = 3), left ventricular outflow tract obstruction (n = 1), and aortic valve replacement via a right anterior minithoracotomy (n = 14) procedures. The venous cannula was placed under transesophageal echocardiography guidance to reach the superior vena cava. Vacuum-assisted venous drainage (between -20 and -35 mm Hg) was used to reach a target flow index of 2.2 L/min/m² at a core temperature of 34 °C using a goal-directed perfusion strategy aimed at a minimum DO₂ of 272 mL/min/m². Cardiopulmonary bypass (CPB) parameters were recorded, and hemolysis-related parameters were analyzed on postoperative days 1 to 7.

RESULTS

Mean body surface area and median body mass index were 1.9 ± 0.2 m² and 25.2 (23.4, 30.2) kg/m². Mean CPB and median cross-clamping times were 107.7 ± 24.4 min and 64.5 (53, 75.8) min, and median CPB flow during cardioplegic arrest was 4 (3.6, 4.2) L/min (median cardiac index 2.1 [2, 2.2] L/min/m²). Venous drainage was considered sufficient by the surgeon in all cases, and insertion and removal were uncomplicated. Mean SvO₂ during CPB was 80.2% ± 5.5%, and median peak lactate was 10 (8, 14) mg/dL, indicating sufficient perfusion. Mean venous negative drainage pressure during cross-clamping was 27.2 ± 12.3 mm Hg. Platelets dropped by 73.6 ± 37.5 K/µL, lactate dehydrogenase rose by 81.5 (44.3, 140.8) U/L, and leukocytes rose by 3.4 (2.2, 7.2) K/µL on postoperative day 1.

CONCLUSIONS

The venous smart canula^® allows for optimal venous drainage at low negative drainage pressures, facilitating sufficient perfusion in MICS.

Technical implementation of percutaneous thrombus aspiration using the AngioVac system

OBJECTIVES

The AngioVac system (AngioDynamics, Latham, NY, USA) provides a method for the minimally invasive, percutaneous aspiration of thrombus formations originating from the central venous system as well as solid matter such as lead vegetations and right atrial thrombi.

METHODS

This retrospective, observational study describes the initial experience in 52 adult patients with the AngioVac system, focusing mainly on the development of the extracorporeal circuit to improve usability and safety.

RESULTS

The mean patient age was 62.9 years (range 23-86 years). 22 patients were female and 30 were male. Indications for percutaneous aspiration were lead vegetations (n = 36; 69.2%), right atrial thrombi (n = 9; 17.3%), central venous thrombi (n = 5; 9.6%) and pulmonary embolisms (n = 2; 3.8%). Successful aspiration was performed in 44 cases (84.6%) and partial success was achieved in five patients (9.6%), while failure to remove thrombi or vegetations occurred in three cases (5.8%). Our practical experience led to the installation of a shunt line for recirculation and the implementation of safety features concerning air handling, which are also employed in minimally invasive extracorporeal bypass circuits. Initial tests monitored the level of negative pressure according to differences in flow and access sites but these still have to be validated on a larger scale.

CONCLUSION

In this initial experience, the AngioVac system appeared to be safe regarding the extracorporeal circulation and the elimination of thrombi and lead vegetations.

The impact of roller pump-assisted cardiotomy suction unit on hemolysis

Hemolysis in cardiac surgery is often related to the contact of blood with air or artificial surfaces. Variations of negative pressure in the suction cannulas may represent an additional factor. Limited data exist on the contribution of a roller pump-assisted (RPA) cardiotomy suction unit to hemolysis. Elevation of free hemoglobin (fHb) following air suction (AS) or suction tip occlusion (STO) events of a pump-assisted cardiotomy suction unit was investigated in a mock circuit filled with blood from slaughtered domestic pigs. AS-associated hemolysis was measured over 240 minutes with 2 minutes of AS occurring every 10 minutes. STO-associated hemolysis was analyzed over 80-minute periods: configuration 1 (c1) comprised a cycle of 20 minutes (min) occlusion and 60 minutes RPA flow (20/60 minutes); c2 comprised 20 cycles of 1/3 minutes; c3 comprised 40 cycles of 0.5/1.5 minutes; and c4 comprised 80 cycles of 0.25/0.75 minutes. The AS setup did not lead to significant hemolysis after 2 (P = .97), 3 (P = .40) or 4 (P = .11) hours. The STO setup showed the greatest hemolysis (ΔfHb of 30 mg/dL) in c1 after 20 minutes. ΔfHb was different in c1 from all other configurations at 20 minutes (P < .0001) and 80 minutes (P < .05). Ex vivo generation of large negative pressures by STO events is the main cause of cardiotomy suction-associated hemolysis. The clinical relevance of this mechanism needs further investigations.

Minimally invasive cardiac surgery in Japan: history and current status

This review examines the historical and current status of minimally invasive cardiac surgery (MICS) in Japan, based on reports that have been published in English. Although enthusiasm for MICS in Japan increased during the 1990s, it waned during the early 2000s because of various limitations. However, the introduction of minimally invasive mitral valve surgery, aortic valve replacement, atrial septal defect closure, and coronary artery bypass has led to the resurgence of MICS in Japan during recent years. Academic societies and a national registry system will play an important role in ensuring that this new wave of MICS is implemented safely and effectively. Off-the-job training and team building are also key factors for implementing a successful MICS program.

Hemolysis During Open-Heart Surgery With Vacuum-Assisted Venous Drainage at Different Negative Pressures in Pediatric Patients Weighing Less Than 10 kilograms

BACKGROUND

This study examined the degree of hemolysis during vacuum-assisted venous drainage at different negative pressures to identify an adequate negative pressure that provides effective venous drainage without significant hemolysis in open-heart surgery in children weighing less than 10 kg.

METHODS

Patients weighing less than 10 kg who underwent surgery for ventricular septal defect or atrial septal defect from 2011 to 2014 were enrolled. We used one of four negative pressures (20, 30, 40, or 60 mm Hg) for each patient. We measured haptoglobin, plasma hemoglobin, aspartate aminotransferase, and lactate dehydrogenase levels in the patients' blood three times perioperatively and determined the potential correlation between the change in each parameter with the level of negative pressure.

RESULTS

Forty-six patients were enrolled in this study (mean age: 7.1 ± 7.0 months, mean body weight: 6.1 ± 1.8 kg). There were no significant differences according to the degree of negative pressure with respect to patient age, body weight, cardiopulmonary bypass (CPB) time, aorta cross-clamping time, blood flow during CPB, or lowest body temperature. All parameters that we measured reflected progression of hemolysis during CPB; however, the degree of change in the parameters did not correlate with negative pressure.

CONCLUSION

In pediatric patients weighing less than 10 kg, the change in the degree of hemolysis did not differ with the amount of negative pressure. We may apply negative pressures up to 60 mm Hg without increasing the risk of hemolysis, with almost same the level of hemolysis using negative pressures of 20, 30, and 40 mm Hg for effective venous drainage and an ideal operative field during open-heart surgery.

A new top-loading venous bag provides vacuum-assisted venous drainage

A new venous bag has been developed, prototyped, and tested. The new bag has its inlet, outlet purge, and infusion tubes extending upward from the top of the bag, and are threaded through, bonded to, and sealed within a flat rigid top plate. This design allows the bag to be hung from its top plate by its tubes. It also allows the bag to be: 1) dropped into or removed from its holder, as is done with existing hard-shell reservoirs so that its weight pulls it into the holder without the need for eyelets and hooks and 2) placed closer to the floor so that gravity drainage is facilitated. The V-Bag® (VB) is easily sealed within an accompanying rigid housing. Once sealed, vacuum applied to the housing is transmitted across the flexible walls of the bag to the venous blood. Thus, vacuum-assisted venous drainage (VAVD) is obtained as it is with a hard-shell reservoir, but without any contact of air with the blood. Bench tests, using a circuit that simulated the venous side of the cardiopulmonary bypass (CPB) circuit, showed that applying suction to the housing increased venous flow, and the fractional increase in flow was not a function of the venous cannula, but of the level of vacuum applied. In the gravity drainage mode, the bubble counts at the outlet of the V-Bag compared to two other bags were lower at any pumping condition. When used in the VAVD mode, bubble counts were two orders of magnitude lower than when using kinetically assisted venous drainage (KAVD) with a centrifugal pump. Results obtained with the VB suggest its clinical usefulness.

Vacuum-assisted drainage in cardiopulmonary bypass: advantages and disadvantages

Systematic review of vacuum assisted drainage in cardiopulmonary bypass, demonstrating its advantages and disadvantages, by case reports and evidence about its effects on microcirculation. We conducted a systematic search on the period 1997-2012, in the databases PubMed, Medline, Lilacs and SciELO. Of the 70 selected articles, 26 were included in the review. Although the vacuum assisted drainage has significant potential for complications and requires appropriate technology and professionalism, prevailed in literature reviewed the concept that vacuum assisted drainage contributed in reducing the rate of transfusions, hemodilutions, better operative field, no significant increase in hemolysis, reduced complications surgical, use of lower prime and of smaller diameter cannulas.

Perioperative intravenous acetaminophen attenuates lipid peroxidation in adults undergoing cardiopulmonary bypass: a randomized clinical trial

BACKGROUND

Cardiopulmonary bypass (CPB) lyses erythrocytes and induces lipid peroxidation, indicated by increasing plasma concentrations of free hemoglobin, F2-isoprostanes, and isofurans. Acetaminophen attenuates hemeprotein-mediated lipid peroxidation, reduces plasma and urine concentrations of F2-isoprostanes, and preserves kidney function in an animal model of rhabdomyolysis. Acetaminophen also attenuates plasma concentrations of isofurans in children undergoing CPB. The effect of acetaminophen on lipid peroxidation in adults has not been studied. This was a pilot study designed to test the hypothesis that acetaminophen attenuates lipid peroxidation in adults undergoing CPB and to generate data for a clinical trial aimed to reduce acute kidney injury following cardiac surgery.

METHODS AND RESULTS

In a prospective double-blind placebo-controlled clinical trial, sixty adult patients were randomized to receive intravenous acetaminophen or placebo starting prior to initiation of CPB and for every 6 hours for 4 doses. Acetaminophen concentrations measured 30 min into CPB and post-CPB were 11.9 ± 0.6 μg/mL (78.9 ± 3.9 μM) and 8.7 ± 0.3 μg/mL (57.6 ± 2.0 μM), respectively. Plasma free hemoglobin increased more than 15-fold during CPB, and haptoglobin decreased 73%, indicating hemolysis. Plasma and urinary markers of lipid peroxidation also increased during CPB but returned to baseline by the first postoperative day. Acetaminophen reduced plasma isofuran concentrations over the duration of the study (P = 0.05), and the intraoperative plasma isofuran concentrations that corresponded to peak hemolysis were attenuated in those subjects randomized to acetaminophen (P = 0.03). Perioperative acetaminophen did not affect plasma concentrations of F2-isoprostanes or urinary markers of lipid peroxidation.

CONCLUSIONS

Intravenous acetaminophen attenuates the increase in intraoperative plasma isofuran concentrations that occurs during CPB, while urinary markers were unaffected.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01366976.

Blood transfusion and infection after cardiac surgery

Cardiac surgery is the largest consumer of blood products in medicine; although believed life saving, transfusion carries substantial adverse risks. This study characterizes the relationship between transfusion and risk of major infection after cardiac surgery. In all, 5,158 adults were prospectively enrolled to assess infections after cardiac surgery. The most common procedures were isolated coronary artery bypass graft surgery (31%) and isolated valve surgery (30%); 19% were reoperations. Infections were adjudicated by independent infectious disease experts. Multivariable Cox modeling was used to assess the independent effect of blood and platelet transfusions on major infections within 60 ± 5 days of surgery. Red blood cells (RBC) and platelets were transfused in 48% and 31% of patients, respectively. Each RBC unit transfused was associated with a 29% increase in crude risk of major infection (p < 0.001). Among RBC recipients, the most common infections were pneumonia (3.6%) and bloodstream infections (2%). Risk factors for infection included postoperative RBC units transfused, longer duration of surgery, and transplant or ventricular assist device implantation, in addition to chronic obstructive pulmonary disease, heart failure, and elevated preoperative creatinine. Platelet transfusion decreased the risk of infection (p = 0.02). Greater attention to management practices that limit RBC use, including cell salvage, small priming volumes, vacuum-assisted venous return with rapid autologous priming, and ultrafiltration, and preoperative and intraoperative measures to elevate hematocrit could potentially reduce occurrence of major postoperative infections.

Venous drainage--gravity or assisted?

Since the early start of cardiopulmonary bypass, vascular access has been recognized as a main variable for obtaining optimal blood flow during cardiopulmonary bypass. In particular, venous drainage can limit the maximum flow as the wide, low-resistance, collapsible veins are connected with smaller stiff cannulas and tubing. Due to the introduction of long venous cannulas for minimally invasive cardiac surgery and the desire to limit hemodilution during cardiopulmonary bypass, more and more centers have started using assisted venous drainage techniques. This article gives an overview of these techniques, with their respective advantages and disadvantages.

Durability improvement of polymer chamber of pulsatile extracorporeal life support system in terms of mechanical change

Twin Pulse Life Support, T-PLS has received the CE mark (2003) and Korea Food and Drug Administration (KFDA) approval (2004) for short-term application as an Extracorporeal Life Support system (ECLS). T-PLS's original intention was to apply for not only short-term but also long-term application such as Extracorporeal ventricular assist device (VAD). Hence, a long-term durability test was conducted. The 1-year reliability of the systems tested in this study did not meet the STS/ASAIO standard of 80% reliability with 60% confidence for a 1-year mission life. However, without the disposable units, which are only designed to operate for 6 h, the 1-year reliability exceeded the STS/ASAIO standard of 80% reliability with 60% confidence. In this study, by using the existing analysis methods and analyzing the root cause of the failure used by a numerical analysis. As eliminating or mitigating of the root cause of the failure, we improved the durability of blood chamber and evaluated the performance of the modified system via the hemolysis test.

Open and closed chest extrathoracic cannulation for cardiopulmonary bypass and extracorporeal life support: methods, indications, and outcomes

Extrathoracic cannulation to establish cardiopulmonary bypass has been widely applied in recent years and includes: (a) repeat surgery, (b) minimally invasive surgery, and (c) cases with diseased vessels such as porcelain, aneurysmal, and dissecting aorta. In addition, the success and relative ease of peripheral cannulation, among other technological advances, has permitted the development of closed chest extracorporeal life support, in the form of cardiopulmonary support and extracorporeal membrane oxygenation. With this development have come applications for cardiopulmonary bypass based support outside the traditional cardiac theatre setting, including emergency circulatory support for patients in cardiogenic shock and respiratory support for patients with severely impaired gas exchange. This review summarises the approach to extrathoracic cannulation for the generalist.

Insufficient filling of vacuum tubes as a cause of microhemolysis and elevated serum lactate dehydrogenase levels. Use of a data-mining technique in evaluation of questionable laboratory test results

Experienced physicians noted unexpectedly elevated concentrations of lactate dehydrogenase in some patient samples, but quality control specimens showed no bias. To evaluate this problem, we used a “latent reference individual extraction method”, designed to obtain reference intervals from a laboratory database by excluding individuals who have abnormal results for basic analytes other than the analyte in question, in this case lactate dehydrogenase. The reference interval derived for the suspected year was 264–530U/L, while that of the previous year was 248–495U/L. The only change we found was the introduction of an order entry system, which requests precise sampling volumes rather than complete filling of vacuum tubes. The effect of vacuum persistence was tested using ten freshly drawn blood samples. Compared with complete filling, 1/5 filling resulted in average elevations of lactate dehydrogenase, aspartic aminotransferase, and potassium levels of 8.0%, 3.8%, and 3.4%, respectively (all p<0.01). Microhemolysis was confirmed using a urine stick method. The length of time before centrifugation determined the degree of hemolysis, while vacuum during centrifugation did not affect it. Microhemolysis is the probable cause of the suspected pseudo-elevation noted by the physicians. Data-mining methodology represents a valuable tool for monitoring long-term bias in laboratory results.

Vacuum-Assisted Venous Drainage during Fetal Cardiopulmonary Bypass

We investigated a miniature magnetically levitated centrifugal blood pump intended to deliver 0.3-1.5 l/min of support to neonates and infants. The back clearance gap between the housing and large volume of the rotor, where the suspension and motor bearings are located, forms a continuous leakage flow path. Within the gap, flow demonstrates a very complex three-dimensional structure: the fluid adjacent to the rotating disk tends to accelerate by centrifugal force to flow radially outwards toward the outlet of the impeller against an unfavorable pressure gradient, which in turn forces blood to return along the stationary housing surfaces. Consequently, one or multiple vortices may be generated in the gap to block blood flow and cause the formation of a retrograde and antegrade leakage flow phenomenon at the gap outlet using an optimization process including extensive computational fluid dynamics (CFD) analysis of impeller refinements, we found that secondary blades located along the back or extended to the side surfaces of the rotor have the capacity to reduce and eliminate the retrograde flow in the back clearance gap. Flow visualization confirmed the CFD-predicted flow patterns. This work demonstrates the utility of CFD-based design optimization to optimize the fluid path of a miniature centrifugal pump.

Venous drainage method for cardiopulmonary bypass in single-access minimally invasive cardiac surgery: siphon and vacuum-assisted drainage

Vacuum-assisted venous drainage (VAVD) can facilitate venous drainage in single-access minimally invasive cardiac surgery (SAMICS). We retrospectively examined the use of VAVD in SAMICS in our hospital for this report. VAVD has been performed according to a VAVD protocol since 2000. Data from the 110 patients who underwent SAMICS in our institute from January 2000 to June 2002 were reviewed retrospectively. The total negative pressure was maintained at no greater than -90 mmHg. Indications for use of VAVD (protocol) were: insufficient venous return by siphon drainage alone, persistent elevation of the central venous pressure (CVP), and, insufficient venous drainage in the operative field. Of 110 patients, 97 (88.2%) underwent VAVD. The body surface area was significantly smaller in the group that did not require VAVD (the non-VAVD group) than in the group that did (VAVD group) (VAVD group versus non-VAVD group: 1.586 +/- 0.175 versus 1.408 +/- 0.153 m(2), P < 0.001). Other factors such as cardiopulmonary bypass time, aortic cross-clamp time, postoperative maximum lactate dehydrogenase, postoperative maximum creatinine, postoperative maximum blood urea nitrogen were similar in the two groups. VAVD is necessary in SAMICS except for small patients. A VAVD total negative pressure of -90 mmHg did not hinder operative procedures or cause clinical problems.

Haemolysis due to active venous drainage during cardiopulmonary bypass: comparison of two different techniques

To facilitate mini-access for cardiac surgery, two different methods of active venous drainage are used: vacuum assisted drainage and centrifugal pump aspiration on the venous line. The aim of this study was to compare the haemolysis produced using these two techniques. From June to December 1999, 50 consecutive patients were operated on using a ministernotomy. All of these patients had valvular surgery for either valve repair or valve replacement (9 MVRepair, 11 MVR, 29 AVR, 1 AVR + MVR). They were randomized into two groups: Group A, 25 patients who underwent surgery where vacuum assisted drainage was used, and Group B, 25 patients where kinetic asssisted venous drainage with centrifugal pump venous aspiration was used. Patient characteristics of both groups were similar for age, gender, body weight, body surface area, height, cardiopulmonary bypass (CPB) time, aortic crossclamp time, priming volume, cardioplegia volume, haemoglobin concentration, haematocrit, serum creatinine, bilirubin, lactate dehydrogenase (LDH), serum glutamic oxaloacetic transaminase (sGOT), serum glutamic pyruvic transaminase (sGPT), aptoglobin, reticulocytes, and platelet count. We checked all these laboratory parameters preoperatively, at the end of CPB, and 2 and 24 h after operation. We also checked haemoglobinuria at these same time points. We assessed blood loss at 6, 12, and 24 h after the operation and calculated total postoperative bleeding. There was a tendency towards a greater increase in LDH, sGOT and sGPT in Group A more than in Group B, but these data did not reach statistical significance. Platelet count was always lower in Group A and aptoglobin increased in Group A more than in Group B. More patients in Group A had haemoglobinuria. These findings indicate that haemolysis is increased more in patients treated with vacuum assisted drainage, when compared to the rise in haemolysis in those treated with centrifugal pump venous drainage. Total bleeding is also greater in Group A.