Approximately 3–5% cardiovascular surgical patients developed postoperative myocardial dysfunction, which require inotropic and/or vasoactive agents as first-line treatment. However, preliminary evidence suggested that administration of inotropic and/or vasoactive agents might be associated with increased morbidity and mortality [1].

Besides that, in some patients whose cardiac function are severely impaired, inotropic and vasoactive agents alone are often ineffective in maintaining stable hemodynamics, which necessitates additional mechanical circulatory support [2, 3]. Intra-aortic balloon counter pulsation (IABP), extracorporeal membrane oxygenation (ECMO) and ventricular assist device (VAD) are three most-commonly used mechanical circulatory support modalities [4]. IABP which can improve coronary perfusion pressure, is the first-line mechanical circulatory support modality for adult patients undergoing cardiovascular surgery [5]. ECMO is capable of providing circulatory and pulmonary support for patients who is refractory to conventional therapy, by means of veno-venous cannulation (V-V ECMO) or veno-arterial cannulation (V-A ECMO) [6]. VAD is reserved for patients with end-stage congestive heart failure who are refractory to conventional therapy as (1) a bridge-to-transplantation (BTT), (2) a bridge-to-recovery (BTR), (3) a bridge to decision (BTD), (4) a destination therapy (DT) [7]. For patients with different types of heart failure, VAD can be classified as left ventricular assist device (LVAD), right ventricular assist device (RVAD) and biventricular assisted device (BiVAD).

Great variance exists among different cardiovascular centers when utilizing these mechanical circulatory support modalities, due to device availability, clinical experience and cost effectiveness issues. Fuwai Hospital is the National Center for Cardiovascular Diseases (NCCD) of China, and one of the largest cardiovascular centers in the world. First clinical application of IABP, ECMO and VAD at Fuwai Hospital was in 1972 [8], 1990 [9] and 1995 [10], respectively. The present study aimed to summarize the single center experience of utilizing IABP, ECMO and VAD in cardiovascular surgical patients.

Patients with cardiogenic shock are conservatively managed using high-dose vasoactive medications for hemodynamic support [11]. However, there are still a large number of patients who die due to circulatory collapse. Mechanical circulatory support had become a necessary means of life support [12]. In recent years, the utilization rate of mechanical circulatory support is increasing. About 3%–8% of the patients undergoing cardiovascular surgery require mechanical circulatory assist devices.

IABP is the most widely used mechanical circulatory support device. IABP can reduce left ventricular afterload and increase coronary artery blood flow, so it is widely used in low cardiac output and failure of weaning off CPB patients. Due to its low complication rate, fast manner of insertion, convenience and lower medical costs, when the patient exceeded the limit dose of vasoactive drugs and had the indications for IABP, the attending physician would be highly motivated to use IABP.

However, IABP with such an excellent advantages also has its limitations. Over the past decade, the appropriate using of IABP has been subject to hevey controversy, the focuses on the automatic regulation of coronary blood flow [13]. Autoregulation of coronary blood flow is based on the premise that myocardial metabolism remains constant. Under normal physiologic circumstances, myocardial blood flow remains arterioles constrict or dilate over a wide range of aortic pressures 45–120 mmHg [14]. This is known as coronary autoregulation. For coronary arteries with automatic adjustment function, IABP implantation is of little significance. Therefore, when IABP was inserted, we should choose the condition of coronary artery autoregulation failure. When coronary blood flow directly depends on perfusion pressure, IABP can improve coronary blood flow [15]. This can only be expected with exhausted coronary autoregulation, typical in acute myocardial infarction complicated by persistent ischemia. In this situation, augmented diastolic pressure was expected to increase myocardial oxygenation [16]. The concept was further corroborated by a sub-study of the CRISP AMI study. Retrospective studies had shown that patients with large ST-elevation myocardial infarction (STEMI) who were treated with IABP had significantly improved survival rate [17, 18]. In persistent ischemia situation, myocardial blood flow was proportional to perfusion pressure. The inflation of IABP during diastole could increase coronary artery perfusion pressure, thereby increasing coronary blood flow and increasing myocardial oxygen supply, which was of great help to the recovery of damaged myocardium [19, 20].

Should IABP be implanted in all patients with cardiogenic shock? The IABP-SHOCK II Trial showed that there was no significant difference in short-term and long-term survival of patients with cardiogenic shock complicating acute myocardial infarction with or without IABP implantation [21, 22]. Thanks to these studies, IABP had become a lower priority, avoiding unnecessary complications and reducing the financial burden on patients. We also believe that IABP was not a routine treatment for all patients with cardiogen Mechanical circulatory support should be considered only if medication and other treatments were difficult to maintain hemodynamic stabilization. This required clinicians to have rich clinical experience, strictly control indications, weigh the advantages and disadvantages of all parties in the face of critically ill patients, and finally formed the most beneficial treatment plan for patients.

In recent years, with the development of cardiovascular surgery, the use of ECMO was also increasing. ECMO played an important role in the treatment of severe cardiopulmonary failure, malignant arrhythmia, postoperative refractory low cardiac output, and failure to escape from cardiopulmonary bypass [23, 24, 25]. ECMO can also be an important adjunctive tool in the management of patients awaiting heart transplantation [26, 27]. In addition, ECMO is often used as an adjunct in cardiopulmonary resuscitation and high-risk coronary interventions, making it an attractive first choice in refractory cardiogenic shock [28]. Although ECMO provides circulatory support with rapid application, it causes an addition increases in afterload and decreases the blood flow in coronary arteries due to retrograde blood flow, which potentially deteriorates cardiac function, increases pulmonary congestion, and an increased need for vasoactive medications.

ECMO was regularly used at Fuwai Hospital for patients with acute cardiogenic shock, The utilization rate of ECMO was increased year by year. However, under the circumstance of COVID-19, the surgical volume and the patients using ECMO decreased in 2020. This could be known form the annual outcomes of cardiovascular surgery of Fuwai Hospital [29]. ECMO and IABP used in combination was routinely used for short-term ventricular assistance. In 2019, the combined use of the two accounted for 54.5% of the total Both applications have achieved excellent outcomes [30]. This result was consistent with Professor Berg’s research [31].

Given the increasing incidence of end stage heart failure and the persistently inadequate supply of donor organs, LVAD was developed to support patients on the wait-list for heart transplantation [32]. LVAD is an important life support equipment, it could prolong the patient’s life and Wait for further treatment. LVAD technology continues improve, as a result, more patients with LVADs could wait longer until getting orthotopic heart transplantation [33]. In the United States, the annual use of LVAD devices had exceeded 2500 annually [34, 35]. The third generation of VAD, featuring magnetic levitation and contactless bearings, is one of the most advanced artificial hearts in the world. CH-VAD was the first-generation of magnetic levitation blood pump with completely independent intellectual property rights in China. It was launched by Professor Shengshou Hu and his artificial heart team in June 2017. By the end of 2020, a total of 42 patients were implanted with LVAD, 40 patients were discharged alive with LVAD device, and 2 patients died perioperative. The device was withdrawn in 1 patient with cardiac function recovery, 3 patients received heart transplantation, the remaining 38 patients were follow up for 363–1073 days. One of these patients had been living with the device for more than 40 months and was the longest in China. The 1-year and 2-year survival rates were 100% and 85%, respectively. According to current clinical results, in addition to heart transplantation, LVAD implantation is gradually becoming the most effective surgical treatment for end-stage heart failure in China [29]. Although LVADs offered a way for patients with end-stage heart disease to extend life, patients with severe comorbidities and some specific cardiomyopathies may be not suitable to implante LVAD, such as dilated cardiomyopathy secondary to KSS, thasthyretin amyloidosis, etc. [36, 37, 38, 39]. In addition, low body surface area, prior aortic valve replacement, coagulopathy, primary right ventricular dysfunction, and sociocultural issues were important factors limiting the use of LAVD [40].

Mechanical circulation support saved people’s lives, while there were also many complications threatening patients’ survival, among which the three most important complications are acute renal failure, bleeding, and infection [41, 42].

Acute kidney injury (AKI) was a common complication after cardiac surgery, with an incidence between 7% and 40% had been reported depending on the definition used [43]. At Fuwai Hospital, the incidence of AKI in patients was 9.1% with IABP implantation and 6.5% with LVAD implantation. Compared to the use of IABP, the use of ECMO had higher incidence of complications. The incidence of AKI was 29.6% in patients treated with ECMO and 34.5% in patients treated with ECMO+IABP. This was an interesting result. Studies had confirmed that compared with continuous flow, pulsatile blood flow was more beneficial to the viscera perfusion [44]. IABP implantation could increase coronary blood flow, reduce myocardial afterload, stabilize hemodynamics, and decrease the use of vasoactive drugs [45], so as to increase renal perfusion and reduce renal toxicity caused by drugs. Patients with LVAD implantation also had a lower incidence of AKI, which may be related to LVAD placement providing better circulation support and ensuring organ perfusion, but the data bias caused by sample size cannot be excluded.

In this study, it was found that ECMO and ECMO+IABP groups had the highest incidence of AKI, which was largely related to the baseline characteristics of patients using ECMO. Poor basic conditions of patients may be one of the reasons for the high incidence of kidney injury. At Fuwai Hospital, ECMO was mainly used to treat patients with acute cardiogenic shock, and postoperative users accounted for 65.9% (29/44) [30]. Impaired cardiac output directly affected renal perfusion, and even with the assistance of ECMO, the incidence of acute kidney injury also was high.

Both coagulant factors and anticoagulant factors were activated when mechanical circulation support was implanted. “Thrombus or hemorrhage?” was a lot depends on the relative balance of the two. The embolization was the result of an abiotic device in contact with the blood. ECMO was a cardiopulmonary bypass device, when blood came into contact with the tube, coagulation factors and platelets were activated and thrombus was easily formed. Therefore, anticoagulant therapy was required if the ECMO was running. At Fuwai Hospital, the anticoagulant measures implemented in ECMO were mainly intravenous injection of ordinary heparin and maintained the ACT 120–200 s. The incidence of bleeding complications in ECMO patients was 35.9%. Bleeding was one of the most common complications in the use of ECMO. In the 2016 Extracorporeal Life Support Organization (ELSO) registry report, the incidence of bleeding with VA-ECMO described was 44% in adult [46] The high bleeding rate of ECMO was closely related to the use of anticoagulant drugs and the stress response. In addition, ECMO was often used in critically ill or post-operative patients, which were high risk factors for bleeding complications.

Hemorrhage complications also represented the most common cause of hospital admission during the course of LVAD patients. Mucosal bleeding was a frequent and morbid complication observed in 20% to 81% of patients depending on age and presence of other important risk factors [33, 47]. At Fuwai Hospital, the bleeding complications of LVAD patients observed in 14.5%. In the European TRACE study, the authors concluded that avoiding antiplatelet therapy might have lowered the risk of bleeding, whilst maintaining stroke and pump thrombosis rates similar to previous trials [48].

Infections were also common complications of mechanical circulatory support therapy. The incidence of using IABP, ECMO and LVAD was 3.7%, 12.7% and 9.7%, respectively. In a study of 74 patients who received LVAD implants after heart transplantation from 2008 to 2017, in Department of Medicine, Stanford University, twenty-one patients (28.3%) developed an infection while supported by an LVAD [49]. A recent analysis by the International Society of Heart and Lung Transplantation Registry for Mechanically Assisted Circulatory Support also showed that infection was the most common complication (37%) [50]. Until 2010, there were 6 cases (9.7%) developed infection while using LVAD at Fuwai Hospital. In the 42 patients implanted with CH-VAD between 2017 and 2020, the incidence of infections were 13%, lower than the reported [30]. Compared with IABP and ECMO, more attention had been paid to LVAD-induced infections. That was because that the use of LVAD was closely related to heart transplantation. Professor Sohail and his team found that patients with device infection before transplantation did increase the postoperative recovery time compared with those without infection, but no significant difference was observed in the survival after transplantation. Therefore, when severe or refractory LVAD device infection cannot be cured, infection suppression can be selected to wait for the donor [51].

In China, although the basic social medical insurance can reimburse part of the cost, mechanical assistance is still too expensive for most patients. The high cost limits the use of mechanical assistance facilities, and various complications during the use of mechanical assistance undoubtedly aggravate the financial burden of patients. The decision should consider the balance of cost, risk and benefit, thefore, all kinds of mechanical assistance support complications and the use of safety research are very beneficial.

The present study suggested that, IABP, ECMO and VAD, either alone or in combination, are effective and safe mechanical circulation support when managing cardiovascular surgical patients with severe hemodynamic instability at Fuwai Hospital.

YTY conceived the idea and edited. XH performed the research and wrote the draft. XH and YTY edited the final version of the manuscript. Both authors read and approved the final manuscript.

Not applicable.

We would like to express our gratitude to all those who helped us during the writing of this manuscript. Thanks to all the peer reviewers for their opinions and suggestions.

This research received no external funding.

The authors declare no conflict of interest.