Vacuum-assisted venous drainage in extrathoracic cardiopulmonary bypass management during minimally invasive cardiac surgery

A novel versatile concept of cardioplegia delivery in cardiac surgery: The ReverseTWO cardioplegia circuit system

Nowadays, the necessity of having a cardioplegia circuit capable of being adapted in order to administer different types of cardioplegia is strategically fundamental, both for the perfusionist and for the cardiac surgeon. This allows to avoid cutting tubes, guarantees sterility and, most of all, limits the number of cardioplegia circuits for the different strategies of cardiac arrest. The novel "ReverseTWO cardioplegia circuit system" is the development of the precedent "Reverse system" where mainly the 4:1 and crystalloid cardioplegia were used, It has the advantage of allowing immediate change of cardioplegia set-up versus four types of cardioplegia technique, when the strategy is unexpectedly changed before the beginning of cardiopulmonary bypass (CPB), is safe and enables the perfusionist to use one single custom pack of cardioplegia. Two pediatric roller pumps are usually used in our centre for cardioplegia administration; they have a standardized calibration (the leading with ¼ inch and the follower with 1/8 inch) and the circuit consequently has two different tube diameters for the two different pumps. The presence in the circuit of two different shunts coupled with two different coloured clamps allows the immediate set-up for different cardioplegia administration techniques utilizing a colour-coding mechanism The aim of this manuscript is to present the new ReverseTWO Circuit. This novel system allows to administer four different cardioplegic solutions (4:1, 1:4, crystalloid, ematic) based on multiple tubes, which can be selectively clamped, identified through a color-coding method. The specificity of this circuit is the great versatility, which leads to numerous advantages, such as reduced risk of perfusion accident and reduced costs related not only to the purchase of different cardioplegia kits but also to the storage. https://youtu.be/ovJBE4ok2Ds.

Vacuum assisted and gravitational venous drainage in aortic valve surgery: A propensity-match study

INTRODUCTION

Vacuum assisted venous drainage (VAVD) is widely adopted in minimally invasive cardiac surgery. VAVD enables the advantage of using smaller cannulae in a reduced surgical field while allowing satisfactory drainage and pump flow. The production of gaseous micro-emboli is a recognized risk associated with VAVD, however no difference in clinical endpoints have been reported between patients operated on with gravity venous drainage (GVD) or with VAVD. Due to the paucity of data on selected surgical populations, we sought to evaluate the early outcomes of patients undergoing isolated aortic valve replacement using VAVD or GVD.

METHODS

Data on 521 patients between 09/2016 and 09/2022 were retrieved from our internal database. Patients were divided into two groups according to use VAVD or GVD. A propensity match analysis was performed to account for difference between the two groups.

RESULTS

The propensity match provided two well balanced cohorts with 129 patients each. A minimally invasive access was used in 97% of the cases in VAVD group vs 98% in GVD group (p = .68). Mean cardiopulmonary by-pass (CPB) time was 71 vs 73 min (p = .74), respectively. There was no difference in lactates peak (p = .19) and urine output during CPB (p = .74). We registered two in-hospital deaths in VAVD cohort (1.6%) vs. no mortality in GVD group (p = .5). Postoperative cerebral stroke occurred in 1 patient in GVD cohort vs. 0 in VAVD (p = 1). Severe postoperative acute kidney injury complicated the course in 16 patients in GVD group and in 5 patients who had VAVD (p = .012). VAVD was associated with a higher number of patients with elevated postoperative AST (p = .07) and Troponin I (p = .01) values.

CONCLUSIONS

The use of VAVD during isolated aortic valve replacement was not associated with increased risks of postoperative complications and in-hospital mortality with results that were at least similar to those registered in a matched cohort of patients operated on with GVD.

Virtually Wall-Less versus Standard Thin-Wall Venous Cannula in the Minimally Invasive Mitral Valve Surgery: Single-Center Experience

Background and Objectives: Minimally invasive cardiac surgery (MICS) has been developing since 1996. Peripheral cannulation is required to perform MICS, and good venous drainage and a bloodless field are crucial for the success of this procedure. We assessed the benefits of using a virtually wall-less cannula in comparison with the standard thin-wall cannula in clinical practice. Materials and Methods: Between January 2021 and December 2022, we evaluated 65 elective patients, who underwent isolated minimally invasive mitral valve surgery. Both the virtually wall-less and the thin-wall cannulas were placed through a surgical cut-down. Patients' characteristics at baseline were similar in the two groups, except for the body surface area (BSA), which was greater in the virtually wall-less group compared to the thin-wall one. In the standard group, the size of the cannula was chosen depending on the patient's BSA, and the choice of the Smartcannula was based on their height. Results: There were no significant differences between the two groups in terms of negative pressure applied, target flow achieved, hemolysis, the need for blood transfusion, and the post-operative increases in liver and renal enzymes. However, in all the patients, the estimated target flow was achieved, thereby showing the better hemodynamic performance of the virtually wall-less cannula, since, in this group, the patients' BSA was significantly greater compared to the thin-wall group. Ultimately, the mean cross-clamp time, as an indirect index of the effectiveness of the venous drainage, is shorter in the virtually wall-less group compared with the thin-wall group. Conclusions: The virtually wall-less cannula should be preferred in minimally invasive mitral valve surgery due to its superior performance in terms of venous drainage compared with the standard thin-wall cannula.

Development of a cannula device for gas fraction removal in surgical drains

The development of low-traumatic surgical drains aimed at maximum possible separation of blood and air, is an important trend in modern medicine. The objective of this work is to create an inexpensive, user-friendly and low-traumatic dynamic blood aspiration system (DBAS). The system allows effective separation of blood and air when drawing blood from a wound under vacuum conditions required for blood aspiration. The operating principle of the system is to separate liquid and gas fractions of the blood-air mixture by modifying the blood intake cannula. The effect is achieved by applying the principles of centrifugal forces of a rotating blood-air flow combined with Archimedes lift forces.

Direct Cannulation in Minimally Invasive Cardiac Surgery With Limited Resources

BACKGROUND

With increasing patient interest in minimally invasive procedures, it is more important than ever for surgeons to be current on the most common minimally invasive techniques in cardiac surgery. As minimally invasive cardiac surgery has evolved, the strategies and approaches to cardiopulmonary bypass access have evolved. Peripheral cannulation is convenient but carries a risk of retrograde dissection, embolization, stroke, and ipsilateral limb ischemia, whereas central aortic cannulation has the advantage of antegrade flow.

METHODS

We report our experience with direct arterial and venous cannulation through a thoracotomy approach without compromising the results. From January 2017 to December 2018, 140 consecutive patients were studied. Mean age was 26 ± 18 years (range, 11 months to 83 years), with 46 patients (32.8%) younger than 12 years and 12 patients weighing less than 10 kg. Spectrum of procedures include atrial septal defect closure (53%), mitral valve repair (14%), ventricular septal defect closure (9%), aortic valve replacement (10%), mitral valve replacement (6%), repair of partial anomalous pulmonary venous drainage (9%), myxoma excision (1%), and ventricular septal defect closure with pulmonary valvotomy (1%).

RESULTS

None of the patients was converted from a minimally invasive to standard median sternotomy. One patient with ventricular septal defect died due to pulmonary hypertensive crises. No patient required reexploration for bleeding, and none had stroke or renal failure. There were no myocardial infarctions or aortic dissections.

CONCLUSIONS

In our experience this approach is a reliable platform for a variety of minimally invasive cardiac surgical procedures and has resulted in low complication rates. The technique can be applied safely to both pediatric and adult populations. Also, it is very cost-effective because regular instruments and cannulas are used.

Minimally invasive aortic valve replacement techniques using endoscopic surgery: 'must dos' and 'preferences'

Aortic valve replacement via a full sternotomy remains the gold standard for aortic stenosis treatment; however, minimally invasive techniques have grown in popularity and continue to evolve. A recent evolution of minimally invasive aortic valve replacement is endoscopic surgical aortic valve replacement: a miniaturized surgical approach under video guidance. To ensure a safe and reproducible procedure, we have developed 'must dos' and 'preferences' for endoscopic surgical aortic valve replacement. These include specific endoscopic surgical skills to avoid severe adverse events or an emergency conversion to a full sternotomy.

Two-Incision Totally Thoracoscopic Approach for Mitral Valve Replacement

Totally thoracosopic mitral valve replacement (MVR) has been applied to mitral stenosis for many years. Three working ports are usually necessary, among which the longest port ranges from 6 to 8 cm. This study aimed to determine the safety and feasibility of the two-incision totally thoracoscopic approach for MVR, with the longest incision of 3 cm.From January 2014 to February 2016, 90 patients with mitral valve stenosis were retrospectively analyzed. Thirty-six (40%) patients were included in the two-incision group and 54 patients were operated on using the sternotomy approach. Perioperative variables and postoperative 3-month follow-up data were analyzed.All patients underwent MVR. Tricuspid valvuloplasty was performed in 23 (25.5%) patients with the Kay technique. The mean total surgery time, cardiopulmonary bypass, and cross-clamp times were longer in the two-incision group (266 ± 42 versus 200 ± 38 minutes; 156 ± 23 versus 121 ± 21 minutes; 100 ± 17 versus 80 ± 17 minutes, respectively) (P < 0.05). The mean postoperative mechanical ventilation time was shorter in the two-incision group (8.6 ± 2.5 versus 11.2 ± 2.6 hours, respectively) (P < 0.05). The mean volume of blood drainage was less in the two-incision group (497 ± 120 versus 730 ± 198 mL, respectively) (P < 0.05). Reopening occurred in one (sternotomy group, 1.8%) patient. No deaths, perivalvular leakage, infectious endocarditis, atelectasis of the lungs, or moderate tricuspid regurgitation were found at the 3-month follow-up.The two-incision totally thoracoscopic approach for MVR is safe and feasible. Concomitant tricuspid valvuloplasty can be conveniently performed. However, further clinical data are needed in future studies.

New, Virtually Wall-Less Cannulas Designed for Augmented Venous Drainage in Minimally Invasive Cardiac Surgery

Objective

Inadequate venous drainage during minimally invasive cardiac surgery becomes most evident when the blood trapped in the pulmonary circulation floods the surgical field. The present study was designed to assess the in vivo performance of new, thinner, virtually wall-less, venous cannulas designed for augmented venous drainage in comparison to traditional thin-wall cannulas.

Methods

Remote cannulation was realized in 5 bovine experiments (74.0 ± 2.4 kg) with percutaneous venous access over the wire, serial dilation up to 18 F and insertion of either traditional 19 F thin wall, wire-wound cannulas, or through the same access channel, new, thinner, virtually wall-less, braided cannulas designed for augmented venous drainage. A standard minimal extracorporeal circuit set with a centrifugal pump and a hollow fiber membrane oxygenator, but no inline reservoir was used. One hundred fifty pairs of pump-flow and required pump inlet pressure values were recorded with calibrated pressure transducers and a flowmeter calibrated by a volumetric tank and timer at increasing pump speed from 1500 RPM to 3500 RPM (500-RPM increments).

Results

Pump flow accounted for 1.73 ± 0.85 l/min for wall-less versus 1.17 ± 0.45 l/min for thin wall at 1500 RPM, 3.91 ± 0.86 versus 3.23 ± 0.66 at 2500 RPM, 5.82 ± 1.05 versus 4.96 ± 0.81 at 3500 RPM. Pump inlet pressure accounted for 9.6 ± 9.7 mm Hg versus 4.2 ± 18.8 mm Hg for 1500 RPM, −42.4 ± 26.7 versus −123 ± 51.1 at 2500 RPM, and −126.7 ± 55.3 versus −313 ±116.7 for 3500 RPM.

Conclusions

At the well-accepted pump inlet pressure of −80 mm Hg, the new, thinner, virtually wall-less, braided cannulas provide unmatched venous drainage in vivo. Early clinical analyses have confirmed these findings.

Short-Term Effects and Safety Analysis of Retrograde Autologous Blood Priming for Cardiopulmonary Bypass in Patients with Cardiac Valve Replacement Surgery

This randomized, double-blind study evaluated the short-term effects and safety of perioperative retrograde autologous priming (RAP) for cardiopulmonary bypass (CPB) in patients with cardiac replacement surgery to determine if this approach is a better substitute for crystal liquids priming in patients with valvular heart disease. We observed that RAP significantly decreased the actual priming volume, preserved the hematocrit and hemoglobin level during CPB to a certain degree, and decreased lactate accumulation in CPB period. Moreover, RAP lowered the volume of transfusion and dosage blood products. Thus, our results showed that RAP approach effectively improved tissue perfusion and lowered intraoperative Lac levels, by reducing the hemodilution, which safely and reliably improve the microcirculation perfusion.

Cannulation Strategies and Pitfalls in Minimally Invasive Cardiac Surgery

For any given cardiac surgery, there are two invasive components: the surgical approach and the cardiopulmonary bypass circuit. The standard approach for cardiac surgery is the median sternotomy, which offers unrestricted access to the thoracic organs-the heart, lung, and major vessels. However, it carries a long list of potential complications such as wound infection, brachial plexus palsies, respiratory dysfunction, and an unpleasant-looking scar. The cardiopulmonary bypass component also carries potential complications such as end-organ dysfunction, coagulopathy, hemodilution, bleeding, and blood transfusion requirement. Furthermore, the aortic manipulation during cannulation and cross clamping increases the risk of dissection, arterial embolization, and stroke. Minimally invasive cardiac surgery is an iconic event in the history of cardiothoracic medicine and has become a widely adapted approach as it minimizes many of the inconvenient side effects associated with the median sternotomy and bypass circuit placement. This type of surgery requires the use of novel perfusion strategies, especially in patients who hold the highest potential for postoperative morbidity. Cannulation techniques are a fundamental element in minimally invasive cardiac surgery, and there are numerous cannulation procedures for each type of minimally invasive operation. In this review, we will highlight the strategies and pitfalls associated with a minimally invasive cannulation.

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.

Percutaneous superior vena cava drainage during minimally invasive mitral valve surgery: a randomized, crossover study

OBJECTIVE

Minimally invasive techniques commonly are applied to mitral valve surgery; however, there has been little research investigating the optimal methods of cardiopulmonary bypass for the right minithoracotomy approach. Controversy exists as to whether a percutaneous superior vena cava drainage cannula (PSVC) is necessary during these operations. The authors, therefore, sought to determine the effect of using a percutaneous superior vena cava catheter on brain near-infrared spectroscopy, blood lactate levels, hemodynamics and surgical parameters.

DESIGN

Randomized, blinded, crossover trial.

SETTING

Tertiary care university hospital.

PARTICIPANTS

Patients undergoing minimally invasive mitral valve surgery via a right minithoracotomy.

INTERVENTIONS

Twenty minutes of either clamped or unclamped percutaneous superior vena cava neck catheter drainage, during mitral valve repair.

MEASUREMENT AND MAIN RESULTS

For the primary outcome of brain near-infrared spectroscopy, there were no differences between the two groups (percutaneous superior vena cava clamped 55.0%±11.6% versus unclamped 56.1%±10.2%) (p = 0.283). For the secondary outcomes pH (clamped 7.35±0.05 versus unclamped 7.37±0.05 p = 0.015), surgical score (clamped 1.96±1.14 versus unclamped 1.22±0.51 p = 0.002) and CVP (clamped 11.6 mmHg±4.8 mmHg versus unclamped 6.1 mmHg±6.1 mmHg p<0.001) were significantly different.

CONCLUSIONS

The use of a percutaneous superior vena cava drainage improved surgical visualization and lowered CVP, but had no effect on brain near infrared spectroscopy during minimally invasive mitral valve surgery. (ClinicalTrials.gov Identifier: NCT01166841).

Perfusion techniques for minimally invasive valve procedures

In this paper, we present, in detail, the simplified perfusion technique that we have adopted since January 2009 and that we have utilized in 200 cases for cardiac minimally invasive valvular procedures that were performed through a right lateral mini-thoracotomy in the 3(rd)-4(th) intercostal space. Cardiopulmonary bypass was achieved by means of the direct cannulation of the ascending aorta and the insertion of a percutaneous venous cannula in the femoral vein. A flexible aortic cross-clamp was applied through the skin incision and cardioplegic arrest was obtained with the antegrade delivery of a crystalloid solution. Gravity drainage was enhanced by vacuum-assisted aspiration. There were no technical complications related to this perfusion technique that we have adopted in minimally invasive surgical procedures.

Superior vena cava drainage during thoracoscopic cardiac surgery: bilateral internal jugular vein sheaths versus one percutaneous superior vena cava cannula

OBJECTIVE

To evaluate bilateral internal jugular vein sheaths as a replacement of one percutaneous superior vena cava cannula for superior vena cava drainage during thoracoscopic cardiac surgery.

DESIGN

A prospective and randomized study.

SETTING

Single cardiovascular institute.

PARTICIPANTS

Adults undergoing thoracoscopic cardiac surgery.

INTERVENTIONS

Patients were randomized into a percutaneous superior vena cava cannula group and a bilateral internal jugular vein sheaths group. The superior vena cava drainage for cardiopulmonary bypass was performed with one percutaneous superior vena cava cannula (14-18 Fr) or the bilateral internal jugular vein sheaths (8 Fr).

MEASUREMENTS AND MAIN RESULTS

Both interventions reached theoretic flow rate in all patients. In patients weighing<50 kg (n=38) and 50-70 kg (n=64), the average central venous pressure values during cardiopulmonary bypass of both groups showed no significant differences. The patients weighing>70 kg (n=15) in the bilateral internal jugular vein sheaths group had a normal average central venous pressure value, but it was significantly higher than that of percutaneous superior vena cava cannula group ([10.5±3.1] mmHg vs. [4.5±4.4] mmHg, p=0.013). The patient satisfaction scale scores for the cervical incisions were significantly higher in the bilateral internal jugular vein sheaths group than in the percutaneous superior vena cava cannula group ([2.6±0.9] vs. [2.1±0.8], p=0.002).

CONCLUSIONS

The bilateral internal jugular vein sheaths were a feasible and effective option to replace one percutaneous superior vena cava cannula during thoracoscopic cardiac surgery, with better patient satisfaction.

Experimental treatment of superior venous congestion during cardiopulmonary bypass

OBJECTIVES

Superior venous outflow obstruction affects cerebral perfusion negatively by reducing cerebral perfusion pressure (CPP). We present a randomized study designed to compare two alternative strategies to preserve the CPP during superior vena cava (SVC) congestion and cardiopulmonary bypass (CPB).

METHODS

Fourteen pigs on bi-caval CPB were subjected to 75% occlusion of the SVC flow. CPP was restored either by vasopressor treatment (VP, n = 7) or by partial relief (PR) of the congestion (n = 7). The cerebral effects of the interventions were studied for 60 min with intracranial pressure (ICP) monitoring, cerebral blood flow measurement, the near-infrared light spectroscopy tissue oxygen saturation index (StO2), arterial and venous blood gas analyses and serial measurements of the glial cell damage marker protein S100β.

RESULTS

Both strategies restored the CPP to baseline levels and no signs of severe ischaemia were observed. In the PR group, the venous and ICPs were normalized in response to the intervention, while in the VP group those parameters remained elevated throughout the experiment. The haemoglobin oxygen saturation in the sagittal sinus (SsagO2) was increased by both VP and PR, while significant improvement in the StO2 was observed only in the PR group. The S100β concentrations were similar in the two groups.

CONCLUSIONS

Experimental SVC obstruction during CPB may reduce the CPP, resulting in impaired cerebral perfusion. Both vasopressor treatment and improved venous drainage can, in the short term, individually restore the CPP during these circumstances.

2011 update to the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists blood conservation clinical practice guidelines

BACKGROUND

Practice guidelines reflect published literature. Because of the ever changing literature base, it is necessary to update and revise guideline recommendations from time to time. The Society of Thoracic Surgeons recommends review and possible update of previously published guidelines at least every three years. This summary is an update of the blood conservation guideline published in 2007.

METHODS

The search methods used in the current version differ compared to the previously published guideline. Literature searches were conducted using standardized MeSH terms from the National Library of Medicine PUBMED database list of search terms. The following terms comprised the standard baseline search terms for all topics and were connected with the logical 'OR' connector--Extracorporeal circulation (MeSH number E04.292), cardiovascular surgical procedures (MeSH number E04.100), and vascular diseases (MeSH number C14.907). Use of these broad search terms allowed specific topics to be added to the search with the logical 'AND' connector.

RESULTS

In this 2011 guideline update, areas of major revision include: 1) management of dual anti-platelet therapy before operation, 2) use of drugs that augment red blood cell volume or limit blood loss, 3) use of blood derivatives including fresh frozen plasma, Factor XIII, leukoreduced red blood cells, platelet plasmapheresis, recombinant Factor VII, antithrombin III, and Factor IX concentrates, 4) changes in management of blood salvage, 5) use of minimally invasive procedures to limit perioperative bleeding and blood transfusion, 6) recommendations for blood conservation related to extracorporeal membrane oxygenation and cardiopulmonary perfusion, 7) use of topical hemostatic agents, and 8) new insights into the value of team interventions in blood management.

CONCLUSIONS

Much has changed since the previously published 2007 STS blood management guidelines and this document contains new and revised recommendations.

Effect of Subzero-Balanced Ultrafiltration on Lung Gas Exchange Capacity after Cardiopulmonary Bypass in Adult Patients with Heart Valve Disease

Objectives: This study was conducted to evaluate the effect of a new ultrafiltration techniquethe subzerobalanced ultrafiltration (SBUF)on lung gas exchange capacity after cardiopulmonary bypass (CPB) in adult patients with heart valve disease.Background: Attenuation of lung gas exchange capacity is one of the most common manifestations of an inflammatory response after CPB.Methods: Ninety-four patients who required CPB for cardiac surgery were randomized into 2 groups according to whether they received SBUF. Gas exchange capacity expressed as the oxygen index (OI), the respiratory index (RI), and the alveolar-arterial oxygen pressure difference (P(A-a)O2) were measured after intubation (T1), at the termination of CPB (T2), on admission to the intensive care unit (ICU) (T3), at postoperative hour 6 (T4), and at postoperative hour 12 (T5).Results: There were no significant differences in gas exchange capacity between the 2 groups at T1, T4, and T5. CPB produced significant changes in OI, RI, and P(A-a)O2 in the control group, whereas these changes were not significantly different in the study group. The OI in the study group was significantly higher at T2, and RI and P(A-a)O2 were significantly lower at T2 and T3. In the study group, the intubation time was shorter, and the transfusion volume within 24 hours postoperatively was less. The 2 groups were comparable with respect to the incidence of respiratory complications, length of stay in the ICU, duration of hospital stay, need for infusions of inotropic agents, and drainage volumes within 24 hours postoperatively.Conclusions: SBUF during CPB can produce an immediate improvement in lung gas exchange capacity, which may effectively minimize pulmonary dysfunction in adult patients undergoing cardiac surgery.

Effect of subzero-balanced ultrafiltration on postoperative outcome of patients after cardiopulmonary bypass

OBJECTIVE

To evaluate the effect of a new ultrafiltration technique - subzero-balanced ultrafiltration technique - on early postoperative outcomes of adult patients undergoing cardiac operations with cardiopulmonary bypass.

METHODS

A total of 120 patients who required cardiopulmonary bypass for cardiac surgery were randomized into two groups, 60 in each group. Patients in the treatment group received subzero-balanced ultrafiltration during cardiopulmonary bypass, while patients in the control group received routine cardiopulmonary bypass. Postoperative outcomes, including hospital mortality and morbidity of the two groups, were analyzed.

RESULTS

Hospital mortality was 0% (0 of 60) in the treatment group versus 1.8% (1 of 60) in the control group (P=1.000). Total hospital complications was lower in the treated patients (11 of 60 [18.3%] versus 22 of 60 [36.7%], P=0.025). Duration of intubation time was shorter and transfusion volume within 24 hours postoperatively was less in patients having received subzero-balanced ultrafiltration during cardiopulmonary bypass (14.35 + or - 1.66 versus 18.64 + or - 1.57 h, P=0.036 and 1.54 + or - 1.56 versus 3.64 + or - 2.67 U/patient, P=0.032). Length of stay on the intensive care unit, duration of hospital stay, need for infusion of inotropic agent and drainage volumes within 24 h postoperatively between the two groups were comparable.

CONCLUSIONS

Subzero-balanced ultrafiltration during cardiopulmonary bypass can effectively decrease the patients' hospital morbidity and the volume of blood transfusion: it also may promote early postoperative recovery of patients. Routine application of subzero-balanced ultrafiltration during adult cardiac operations should not be necessary, but the technique should be compared to other techniques, e.g. MUF, in further studies.

Assisted venous drainage on cardiopulmonary bypass for minimally invasive aortic valve replacement: is it necessary, useful or desirable?

Assisted venous drainage (AVD) is considered an essential component of the cardiopulmonary bypass (CPB) circuit for minimal access aortic valve replacement (mAVR). The rationale/necessity for AVD in every patient has not been fully elucidated. Data from consecutive patients undergoing isolated first-time mAVR by a single surgeon from March 2006 to October 2008 was prospectively collected. All cases were cannulated centrally. Venous drainage was by a three-stage cannula (Medtronic MC2X) via the right atrial appendage. AVD was utilised intraoperatively at the discretion of the perfusionist and/or surgeon to maintain the required flow rate. Pre- and perioperative data were compared between the two groups. Fifty-seven patients underwent mAVR. Twenty-nine did not require assistance (AVD-), 28 did (AVD+). There were no significant differences between the two groups' age, sex distribution, body mass index and risk stratification data. Patients who required AVD had significantly higher body surface areas (BSAs) [1.93 m(2) (1.56-2.46) vs. 1.79 m(2) (1.41-2.26), P=0.03] and consequent higher CPB flow required [4.62 l/min (3.74-5.90) vs. 4.29 l/min (3.38-5.42), P=0.03]. Patients who required AVD tended to have longer ischaemic times [79.5 min (48-135) vs. 69 min (47-126), P=0.06]. AVD during mAVR is not necessary in every patient. We found it to be necessary in patients with higher BSA (consequently requiring a higher flow rate on CPB).

A cardioplegia circuit with versatility: the 'ReVerse' system. How to do it

Various methods of cardioplegia administration have been used in cardiac surgery: crystalloid, blood and mixed crystalloid/blood. Each of these types of cardioplegia administration typically needs a different circuit. This may correspond to an increase in cost and the time needed to change the circuit if required. When various modifications are performed on the circuit, this also increases the risk of contamination. In order to simplify the management of differing cardioplegia circuits, we devised one circuit for all solutions in all situations by adding one modification. The ReVerse cardioplegia circuit system is a description of a two-pump cardioplegia circuit which is adaptable to either blood or crystalloid cardioplegia. The change from one mode to another requires a manoeuvre of two clamps, allowing the blood solution to travel through shunt tubing into the apposite pumphead. In our experience the versatility of this circuit is a fast, safe method to administrate all types of cardioplegia solution, saving the space taken up by storing multiple circuits.