Aortic valve replacement with minimal extracorporeal circulation versus standard cardiopulmonary bypass

Minimally invasive versus standard extracorporeal circulation system in minimally invasive aortic valve surgery: a propensity score-matched study

OBJECTIVES

The impact of minimally invasive extracorporeal circulation (MiECC) systems on the clinical outcomes of patients undergoing minimally invasive aortic valve replacement (MI-AVR) has still to be defined. This study compared in-hospital and 1 year outcomes of MI-AVR interventions using MiECC systems versus conventional extracorporeal circulation (c-ECC).

METHODS

Data from 288 consecutive patients undergoing primary isolated MI-AVR using MiECC (n = 102) or c-ECC (n = 186) were prospectively collected. Treatment selection bias was addressed by the use of propensity score matching (MiECC vs c-ECC). After propensity score matching, 2 groups of 93 patients each were created.

RESULTS

Compared with c-ECC, MiECC was associated with a higher rate of autologous priming (82.4% vs 0%; P < 0.001) and a greater nadir haemoglobin (9.3 vs 8.7 g/dl; P = 0.021) level and haematocrit (27.9% vs 26.4%; P = 0.023). Patients who had MiECC were more likely to receive ultra-fast-track management (60.8% vs 26.9%; P < 0.001) and less likely to receive blood transfusions (32.7% vs 44%; P = 0.04). The in-hospital mortality rate was 1.1% in the MiECC group and 0% in the c-ECC group (P = 0.5). Those in the MiECC group had reduced rates of bleeding requiring revision (0% vs 5.3%; P = 0.031) and postoperative atrial fibrillation (AF) (30.1% vs 44.1%; P = 0.034). The 1-year survival rate was 96.8% and 97.5% for MiECC and c-ECC patients, respectively (P = 0.4).

CONCLUSIONS

MiECC systems were a safe and effective tool in patients who had MI-AVR. Compared with c-ECC, MiECC promotes ultra-fast-track management and provides better clinical outcomes as regards bleeding, blood transfusions and postoperative AF. Thus, by reducing surgical injury and promoting faster recovery, MiECC may further validate MI-AVR interventions.

Minimized extracorporeal circulation in non-coronary surgery

Minimally invasive extracorporeal circulation (MiECC) technology is characterized by improved biocompatibility due to closed-loop design, minimized priming, and markedly reduced artificial surface. Despite well-evidenced clinical advantages in coronary surgery, MiECC penetration in complex open-heart surgery is low. Concerns have been raised by surgeons and perfusionist regarding safety of perfusion in situations when the heart is opened and air is entering the closed system. Moreover, issues of blood and volume management are deemed impractical without having a reservoir. In the evolution of MiECC safety aspects as well as means of air and volume management have been addressed. The integration of active air removal devices, and the possibility of venting and volume buffering made MiECC suitable for valvular or even more complex surgery. However, typical clinical benefits found with MiECC in coronary artery bypass grafting (CABG) surgery, in particular blood sparing effects, were not reproducible. Air handling and blood management remain the main issues of MiECC in non-coronary surgery. With the introduction of modular (type IV) MiECC systems containing a second, accessory circuit for immediate conversion to open cardiopulmonary bypass (CPB), the last obstacles seem to be cleared away. The first reports using this latest development in MiECC technology sound promising. It is now up to the cardiac surgical community to adopt this technology and produce data helping to answer the question whether MiECC is the best perfusion strategy for all comer's cardiac surgery.

Aortic valve replacement with or without myocardial revascularization in octogenarians. Can minimally invasive extracorporeal circuits improve the outcome?

OBJECTIVE

The positive impact of minimally invasive extracorporeal circuits (MiECC) on patient outcome is expected to be most evident in patients with limited physiologic reserves. Nevertheless, most studies have limited their use to low-risk patients undergoing myocardial revascularization. As such, there is little evidence to their benefit outside this patient population. We, therefore, set out to explore their potential benefit in octogenarians undergoing aortic valve replacement (AVR) with or without concomitant myocardial revascularization.

METHODS

Based on the type of the utilized ECC, we performed a retrospective propensity score-matched comparison among all octogenarians (n = 218) who received a primary AVR with or without concomitant coronary artery bypass grafting in our institution between 2003 and 2010.

RESULTS

A MiECC was utilized in 32% of the patients. The propensity score matching yielded 52 matched pairs. The 30-day postoperative mortality (2% vs. 10%; p=0.2), the incidence of low cardiac output (0% vs. 6%; p=0.2) and the Intensive Care Unit (ICU) stay (2.5 ± 2.6 vs. 3.8 ± 4.7 days; p=0.06) were all in favour of the MiECC group, but failed to reach statistical significance while the 90-day postoperative mortality did (2% vs. 16%; p=0.02).

CONCLUSION

MiECCs have a positive influence on the outcome of octogenarians undergoing AVR with or without concomitant coronary artery bypass grafting. Their use should, therefore, be extended beyond isolated coronary artery bypass graft (CABG) surgery.

A comparison between minimized extracorporeal circuits and conventional extracorporeal circuits in patients undergoing aortic valve surgery: is 'minimally invasive extracorporeal circulation' just low prime or closed loop perfusion ?

INTRODUCTION

Even though results have been encouraging, an unequivocal conclusion on the beneficial effect of minimally invasive extracorporeal circulation (MiECC) in patients undergoing aortic valve surgery cannot be derived from previous publications. Long-term outcomes are rarely reported and a significant decrease in operative mortality has not been shown. Most studies have a limited number of patients and are underpowered. They merely report on short-term results of a heterogeneous intraoperative group using different types of ECC system in aortic valve surgery. The aim of the present study was to determine whether MiECC systems are more beneficial than conventional extracorporeal systems (CECC) with regard to mortality, hospital stay and inflammation and with only haemodilution and blood-air interface as differences.

METHODS

We retrospectively analysed data regarding mortality, hospital stay and inflammation in patients undergoing isolated aortic valve surgery. Forty patients were divided into two groups based on the type of extracorporeal system used; conventional (n=20) or MiECC (n=20).

RESULTS

Perioperative blood product requirements were significantly lower in the MiECC group (MiECC: 0.2±0.5 units vs CECC: 0.9±1.2 units, p=0.004). No differences were seen postoperatively regarding mortality (5% vs 5%, p=0.99), total length of hospital stay (10.6±7.2 days (MiECC) vs 12.1±5.9 days (CECC), p=0.39) or inflammation markers (CRP: MiECC: 7.09±13.62 mg/L vs CECC: 3.4±3.2 mg/L, p=0.89).

CONCLUSION

MiECC provides circulatory support that is equally safe and feasible as conventional extracorporeal circuits. No differences in mortality, hospital stay or inflammation markers were observed.

A Meta-Analysis of Miniaturized Versus Conventional Extracorporeal Circulation in Valve Surgery

The effects of miniaturized extracorporeal circulation in patients operated on for heart valve surgery are still inconsistent. We performed a meta-analysis of eight studies involving 1,011 patients to evaluate the comprehensive effects of miniaturized extracorporeal circulation. The results suggested its application significantly reduced the length of stay in the intensive care unit and total hospital stay after heart valve surgery, but no significant effects on reducing postoperative morbidity and mortality were observed. Further studies with long-term follow-up are needed to confirm our results.

Correlation of Preoperative Renal Insufficiency With Mortality and Morbidity After Aortic Valve Replacement: A Propensity Score Matching Analysis

Preoperative end-stage renal disease carries a high mortality and morbidity risk after aortic valve replacement (AVR), but the effect of renal insufficiency remains to be clarified. Through propensity score analysis, we compared the preoperative demographics, perioperative profiles, and outcomes between patients with and without renal insufficiency. From August 2005 to November 2014, 770 adult patients underwent AVR in a single institution. Patients were classified according to their estimated glomerular infiltration rate (eGFR) as renal insufficiency (eGFR: 30-89 mL/min/1.73 m) or normal (eGFR, ≥90 mL/min/1.73 m). Propensity scoring was performed with a 1:1 ratio, resulting in a matched cohort of 88 patients per group. Demographics, comorbidities, and surgical procedures were well balanced between the 2 groups, except for diabetes mellitus and eGFR. Patients with renal insufficiency had higher in-hospital mortality (19.3% versus 3.4%, P < 0.001), a greater need for postoperative hemodialysis (14.8% versus 3.1%, P = 0.009), and prolonged intubation times (>72 hour; 25% versus 9.1%, P = .008), intensive care unit stays (8.9 ± 9.9 versus 4.9 ± 7.5 days, P = .046), and hospital stays (35.3 ± 31.7 versus 24.1 ± 20.3 days, P = .008), compared with those with normal renal function. Multivariate analysis confirmed that preoperative renal insufficiency was an in-hospital mortality predictor (odds ratio, 2.33; 95% confidence interval, 1.343-4.043; P = .003), as were prolonged cardiopulmonary bypass time, intraaortic balloon pump support, and postoperative hemodialysis. The 1-year survival significantly differed between the 2 groups including (normal 87.5% versus renal insufficiency 67.9%, P < .001) or excluding in-hospital mortality (normal 90.7% versus renal insufficiency 82.1%, P = .05). Patients with preoperative renal insufficiency who underwent AVR had higher in-hospital mortality rates and increased morbidities, especially those associated with hemodynamic instabilities requiring intraaortic balloon pump support or hemodialysis. Earlier surgical intervention for severe aortic valve disease should be considered in patients who show deteriorating renal function during follow-up.

Impact of closed minimal extracorporeal circulation on microvascular tissue perfusion during surgical aortic valve replacement: intravital imaging in a prospective randomized study

OBJECTIVES

Closed minimal extracorporeal circulation (MECC) systems currently do not represent the standard of surgical care for open-heart surgery. Yet, considering the beneficial results reported for coronary artery bypass graft (CABG) surgery, we used an MECC system in aortic valve replacement (AVR) and analysed the effects on intraoperative microvascular perfusion in comparison with conventional open extracorporeal circulation (CECC).

METHODS

In the current study, we analysed alterations in microvascular perfusion at 4 predefined time points (T1-T4) during surgical AVR utilizing orthogonal polarization spectral (OPS) imaging. Twenty patients were randomized for being operated on utilizing either MECC or CECC. Changes in functional capillary density (FCD, cm/cm(2)), mircovascular blood flow velocity (mm/s) and vessel diameter (μm) were analysed by a blinded investigator.

RESULTS

After the start of extracorporeal circulation and aortic cross-clamping (T2), both groups showed a significant drop in FCD, but with a significantly higher FCD in the MECC group (153.1 ± 15.0 cm/cm² in the CECC group vs 160.8 ± 12.2 cm/cm² in the MECC group, P = 0.034). During the late phase of the cardiopulmonary bypass (CPB) (T3), the FCD was still significantly depressed in both treatment groups (153.5 ± 14.6 cm/cm² in the CECC group, P <0.05 vs 'T1'; 159.5 ± 12.4 cm/cm² in the MECC group, P <0.05 versus 'T1'). After termination of CPB (T4), the FCD recovered in both groups to baseline values. Microvascular blood flow velocity tended to remain at a higher level in the MECC group, whereas haemodilution during CPB was significantly reduced in the MECC group.

CONCLUSIONS

The use of MECC in AVR did not affect procedural safety and, resulted in beneficial preservation of microvascular blood flow velocity and significantly reduced haemodilution during CPB. In contrast to CABG surgery, the use of MECC did not improve FCD during surgical AVR. Clinical advantages possibly resulting from attenuated haemodilution and preservation of microvascular blood flow velocity require further validation in larger patient cohorts.

Feasibility and safety of minimized cardiopulmonary bypass in major aortic surgery

OBJECTIVES

Conventional cardiopulmonary bypass causes haemodilution and is a trigger of systemic inflammatory reactions, coagulopathy and organ failure. Miniaturized cardiopulmonary bypass has been proposed as a way to reduce these deleterious effects of conventional cardiopulmonary bypass and to promote a more physiological state. The use of miniaturized cardiopulmonary bypass has been reported in low-risk patients undergoing valve and coronary artery bypass graft (CABG) surgery. However, little is known about its application in major aortic surgery.

METHODS

From February 2007 to September 2010, 49 patients underwent major aortic surgery using the Hammersmith miniaturized cardiopulmonary bypass (ECCO, Sorin). Data were extracted from medical records to characterize preoperative comorbidities (EuroSCORE), perioperative complications and the use of blood products. The same data were collected and described for 328 consecutive patients having similar surgery with conventional cardiopulmonary bypass at the Bristol Heart Institute, our twinned centre, during the same period.

RESULTS

The miniaturized cardiopulmonary bypass group had a median EuroSCORE of 8 [inter-quartile range (IQR): 5-11], 13% had preoperative renal dysfunction and 20% of operations were classified as emergency or salvage. Thirty-day mortalities were 6.4; and 69, 67 and 74% had ≥ 1 unit of red cells, fresh frozen plasma (FFP) and platelets transfused, respectively. Eight percent of patients experienced a renal complication, and 8% a neurological complication. The conventional cardiopulmonary bypass group was similar, with a EuroSCORE of 8 (IQR: 6-10); 30-day mortalities were 9.4; and 68, 62 and 74% had ≥ 1 unit of red cells, FFP and platelets transfused, respectively. The proportions experiencing renal and neurological complications were 14 and 5%.

CONCLUSIONS

Our experience suggests that miniaturized cardiopulmonary bypass is safe and feasible for use in major aortic cardiac surgery. A randomized trial is needed to evaluate miniaturized cardiopulmonary bypass formally.

Minimal access aortic valve replacement using minimal extracorporeal circuit

A minimal extracorporeal circuit has been shown to decrease the transfusion rate, cardiac and neurological damage in coronary surgery. We describe in detail a technique for minimal-access aortic valve replacement using a minimal extra-corporeal circuit, and provide surgical and perfusion tips to maintain antegrade perfusion and a clear surgical field.