Temporary mechanical circulatory support: insights and evolving strategies

Abstract

Purpose

The goal of this study is to evaluate the utilization and outcomes of temporary mechanical circulatory support (MCS) among patients listed for cardiac transplantation (CT). There is a constant threat of sudden clinical deterioration in these patients that could necessitate emergent MCS. All advanced heart failure and transplant centers in India are plagued by issues of late referrals, low organ donation rates, and financial constraints. Here, we share our experience and explain our evolving strategies tailored to improve outcomes.

Methods

Single-center retrospective analysis of temporary MCS implanted in patients listed for CT from January 1, 2015, to December 31, 2019.

Results

A total of 35 patients had 41 MCS implantations. Twenty-four cases were pre-transplant and 11 cases were post-transplant. Veno-arterial extracorporeal membrane oxygenator was the most commonly (20 cases, 44.4%) used MCS modality. Primary outcome of in-hospital mortality was noted in 17 patients (48.5%) in this high-risk profile. All but 2 of the 12 patients that underwent pre-transplant MCS, and were bridged to cardiac transplant, survived the index hospitalization accounting for 90% survival in this subset of patients. The secondary outcome of MCS-related vascular injury was observed in 9 patients (25.7%).

Conclusion

This single-center observational study demonstrates that early planning and timely institution of MCS improves outcomes in high-risk MCS patients bridged to cardiac transplant. The incidence of MCS-related vascular complications can be improved with development of standard operating protocols.

Aim

This study aims to evaluate the utilization and outcomes of temporary mechanical circulatory support (MCS) among patients listed for cardiac transplantation. We also share our experience and explain our evolving strategies pertaining to MCS tailored to improve the outcomes.

Introduction

Heart failure (HF) is a continuous spectrum of changes, ranging from the subtle loss of normal cardiac function, without any symptoms, to symptoms refractory to medical therapy. A patient with cardiomyopathy may maintain normal ventricular function, while some will show unpredictable sudden deterioration.

In decompensated heart failure, signs and symptoms of HF persist, despite maximal pharmacological therapy, and are refractory to adjustments in oral medications [1].

The HF clinic has been established with the intent to identify such patients with advanced HF that may need a cardiac transplant or long-term MCS. With the help of serial follow-up and monitoring, the HF clinic also detects such patients at an earlier stage, before they deteriorate to Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) level < 4 [2].

Over time, despite the body’s physiological compensatory mechanisms, and adequate pharmacotherapy, the patients on the waitlist for transplantation may experience a deterioration in vital organs such as the lungs, liver, kidneys, and brain. This deterioration could be a result of a chronic state of inadequate perfusion or secondary to passive volume congestion.

Considering the low rate of organ donation in India, it is of utmost importance to preserve these vital organs, by either pharmacological optimization and/or MCS and keeping the recipient worthy of cardiac transplant.

Here, we describe our experience and outcomes of MCS at an advanced heart failure and cardiac transplant program in Mumbai, India, from January 2015 to December 2019. Furthermore, we describe the valuable lessons learned over the years and our evolving perspectives keeping in view the MCS options that were readily available to us.

Methods

Study design

This single-center retrospective analysis was conducted at the advanced heart failure and cardiac transplant center in a quaternary care hospital in Mumbai, India. Patient baseline data and follow-up data were collected in a retrospective manner by review of medical records and stored in a central database. The institutional review board approved the study.

Patient selection

All patients implanted with temporary MCS devices including intra-aortic balloon pump (IABP), extracorporeal membrane oxygenator (ECMO), temporary left ventricular assist device (LVAD), temporary right ventricular assist device (RVAD), and Koji-VAD (ventricular assist device with a membrane oxygenator) between January 1, 2015, and December 31, 2019, and listed for cardiac transplant, were included in the study. Any patient who had MCS, but not listed for transplant, was excluded.

Outcomes

The primary outcome of this study was to analyze in-hospital mortality, which was defined as death during the index admission involving MCS.

The secondary outcomes were considered to scrutinize the complications and morbidity associated with MCS and to improvise the protocols to improve the outcomes. The following secondary outcomes were considered:

1. MCS-related limb ischemia or peripheral vascular injury, which was defined as any injury to peripheral blood vessels during cannulation requiring repair or any manifestation of limb ischemia, including loss of pulses on vascular doppler.

2. North-south (Harlequin) syndrome, pulmonary edema, and hemorrhage.

3. Mechanical pump or circuit dysfunction which was defined as any instance of mechanical pump dysfunction requiring replacement of pump or circuit components.

Statistical methods

The numeric continuous data were summarized by descriptive analysis like mean, maximum, and minimum. Categorical variables were expressed as a percentage. For the statistical significance of numeric data, the Fisher exact test was used. The value of p < 0.05 was considered significant.

MCS and implantation techniques

IABP and ECMO were the readily available MCS options in this transplant program since the time of its inception in 2015. Later, in early 2017, the program procured a CentriMag® pump.

All the MCS implantations were performed under transesophageal echocardiography (TEE) guidance. An ultrasound vascular study of the femoral, subclavian, and axillary vessels was also performed, pre-MCS implantation, to aid in deciding optimal cannulation strategy.

IABP was inserted with standard Seldinger technique, either at the bedside or in the operating room.

Veno-arterial (VA)-ECMO

The femoral vein was the preferred inflow (venous) cannulation site and either the femoral or axillary artery was the preferred outflow (arterial) site of cannulation. In patients who had axillary artery cannulation, an 8-mm Dacron graft (Terumo^R Vascutek) was used (Fig. 1). Direct femoral artery cannulation was done using either open or ultrasound-guided percutaneous Seldinger technique with distal perfusion cannula.

Fig. 1.

Koji-VAD cannulation via lateral thoracotomy in a non-ischemic cardiomyopathy patient with severe acute biventricular failure (INTERMACS 1 profile): 1, axillary artery outflow cannula; 2, left ventricular apical inflow cannula; 3, Romovac® suction drain; 4, femoral venous inflow cannula; 5, intra-aortic balloon pump; 6, left femoral venous sheath for temporary pacing; 7, tube clamp on the LV cannula to regulate left ventricular unloading; 8, Y-connector joining the 2 inflow cannulae to the CentriMag® pump

In the setting of ongoing cardiac arrest during MCS implantation (eCPR, ECMO-aided cardiopulmonary resuscitation), the femoral artery and vein were chosen as outflow and inflow sites, respectively. To expedite the procedure, venous and arterial cannulations were performed by two teams on both extremities simultaneously. ECMO circuit consisted of a hollow fibre oxygenator with a centrifugal pump (Macquet, Medos, or CentriMag®) and an integrated heat exchanger. Intravenous unfractionated heparin was used for anticoagulation with goal activated clotting time (ACT) of 180 to 220 s.

Temporary LVAD

The temporary LVADs were placed using the standard surgical technique via a median sternotomy, without utilizing cardiopulmonary bypass. The inflow cannula was inserted via the left ventricular (LV) apex in all but one patient, where the cannula was placed in the left atrium due to the relatively small size of the left ventricle. The inflow cannula was inserted in the LV apex under TEE guidance confirming the site and direction of the cannula toward the mitral valve and away from the interventricular septum. The outflow LVAD cannula was placed directly in the ascending aorta. In two patients who were already on peripheral VA-ECMO support with axillary artery cannulation, ECMO was converted into temporary LVAD by placing a LV apical cannula via left thoracotomy. The LVAD inflow and outflow cannulae were connected via a CentriMag® pump with magnetic levitation technology. Intravenous unfractionated heparin was used for anticoagulation with goal ACT of 180 to 200 s. For the purpose of assessing native cardiac function recovery, the pump speeds were reduced gradually followed by close monitoring of echocardiographic, hemodynamic, and clinical parameters. Only one temporary LVAD patient, who recovered enough native LV function, was gradually weaned off the CentriMag® pump over days and then eventually decannulated under TEE guidance. The remaining LVAD patients were bridged to cardiac transplant and had their decannulations performed at the time of native heart explant.

Temporary RVAD

The temporary RVADs were centrally placed, post-cardiac transplant, while weaning off cardiopulmonary bypass. The RVAD inflow cannula was directly placed in the right atrium and outflow cannula was placed in the main pulmonary artery using 8-mm Dacron graft (Terumo^R Vascutek). The circuit was supported with a CentriMag® pump. Intravenous unfractionated heparin was used for anticoagulation with goal ACT of 180 to 200 s. The weaning protocol for RVAD was similar to the LVAD weaning protocol as mentioned above. The RVAD was gradually weaned over days under TEE guidance and then eventual decannulation was performed in the operating theater.

VAD with oxygenator (Koji-VAD)

This modality of MCS was performed as per the method described first by Takeda et al. [3]. Koji-VAD was performed on patients who were already on ECMO. The femoral venous and LV apical cannulae were connected with Y connector as an inflow of the circuit and an oxygenator was added, as in ECMO. Axillary artery cannulation was used as an outflow of the circuit. This circuit was supported with the CentriMag® pump (Fig. 1). To achieve graded unloading of the LV and right ventricle (RV), a tube clamp was applied (as seen in Fig. 1) on the inflow cannulae to regulate the flows. Furthermore, flow probes used to measure flow in individual cannulae and TEE imaging to assess central position of the interventicular septum were used to ensure ideal unloading of the LV and RV. The goal of the additional LV apical cannula was to ensure adequate unloading of LV, with maintenance of minimal pulsatility (aortic valve opening partially at least in every other beat). Depending on the severity of native LV and RV dysfunction and the degree of elevation of filling pressures on each side, the degree of clamping of the inflow cannulae and the consequent flow estimated by flow probes differed in each case. Intravenous unfractionated heparin was used for anticoagulation with goal ACT of 180 to 200 s.

Results

We analyzed 41 cases of MCS involving 35 patients from January 2015 to December 2019. All 35 patients were listed for cardiac transplantation. The mean age for the total cohort was 44 years with the majority of them being males (n = 26; 80%). Out of the total cohort of 35 patients, 20 had non-ischemic cardiomyopathy, 10 had ischemic cardiomyopathy, 4 had acute viral myocarditis, and 1 had hypertrophic cardiomyopathy.

The demographics, etiology of cardiomyopathy, details of the MCS configuration, and the timing of MCS institution relative to cardiac transplant are shown in Table 1. There were six patients who required more than one MCS device, either simultaneously or at separate times, during their index hospitalization. Details of these six patients are provided in Table 2. VA-ECMO was the most commonly utilized modality of temporary MCS (20 cases, 48.7%) followed by IABP (9 cases, 21.4%) and CentriMag® LVAD (6 cases, 14.2%).

Table 1.

Patient demographics and timing of MCS institution relative to cardiac transplant

	Total patients	IABP cases	VA ECMO cases	LVAD cases	RVAD cases	Koji-VAD with oxygenator cases
Total (n)	35	9	20	6	2	4
Age, years (mean)	44	47	37	31	9	45
Gender, M:F (n)	26:9	5:4	14:6	6:0	2:0	4:0
Etiology of cardiomyopathy
Ischemic	10	6	6	0	0	2
Non-ischemic	20	3	11	4	2	2
Myocarditis	4	0	3	1	0	0
Hypertrophic	1	0	0	1	0	0
Timing of MCS institution relative to transplant
Pre-transplant MCS: bridged to transplant	13	3	6	4	0	3
Pre-transplant MCS: deceased on waitlist	8	2	6	1	0	1
Pre-transplant MCS: recovered without a transplant	3	0	2	1	0	0
Post-transplant MCS	11	4	6	0	2	0

IABP, intra-aortic balloon pump; Koji-VAD, Koji ventricular assist device; ECMO, extracorporeal membrane oxygenation; LVAD, left ventricular assist device; RVAD, right ventricular assist device

Table 2.

Patients who required more than one mechanical circulatory support device

	Etiology of cardiomyopathy	MCS devices	Explanation
Patient 1	Ischemic (remote history of CABG)	IABP + Koji-VAD via lateral thoracotomy	IABP placed at outside center not providing sufficient hemodynamic support
Patient 2	Non-ischemic	ECMO ➔ CentriMag LVAD via lateral thoracotomy	Pulmonary edema due to high LV afterload on ECMO
Patient 3	Ischemic (recent history of CABG)	IABP ➔ Koji-VAD via median sternotomy	IABP not providing sufficient hemodynamic support for biventricular failure
Patient 4	Ischemic	IABP + ECMO	Reduce LV afterload on ECMO
Patient 5	Non-ischemic	ECMO ➔ Koji-VAD ➔ RVAD	Pulmonary edema due to high LV afterload on ECMO switched to Koji-VAD bridged to transplant. Post-transplant RV dysfunction requiring RVAD support.
Case 6	Non-ischemic	ECMO ➔ LVAD	Pulmonary edema due to high LV afterload on ECMO

CABG, coronary artery bypass grafting; IABP, intra-aortic balloon pump; Koji-VAD, Koji ventricular assist device; ECMO, extra corporeal membrane oxygenation; LVAD, left ventricular assist device; RVAD, right ventricular assist device; LV, left ventricle; RV, right ventricle

IABP was utilized mainly in ischemic cardiomyopathy patients (7 out of 9 cases). Of the total 9 cases, 5 were instituted pre-transplant and of these 2 cases did not survive cardiac transplant. Of note, there were 2 cases of IABP being used in combination with VA-ECMO, to aid in afterload reduction to the left ventricle. The remaining 4 IABP cases were inserted post-transplant for primary graft dysfunction/metabolic hemodynamic instability, out of which 2 survived.

Out of the 20 cases of VA-ECMO, 14 were pre-transplant and the remaining 6 post-transplant. Out of the 14 pre-transplant initiated cases, 6 cases were successfully bridged to cardiac transplantation and 2 cases recovered enough cardiac function to be weaned off MCS. The remaining 6 cases of pre-transplant ECMO did not survive until cardiac transplantation, despite remaining on ECMO support for 8 to 16 days. Their deaths were due to adverse events such as bleeding, infections, pulmonary edema, and disseminated intravascular coagulopathy (DIC).

Temporary LVAD was utilized solely as a pre-transplant strategy. Out of the total 6 cases with LVAD, 4 were successfully bridged to cardiac transplantation and 1 recovered cardiac function and was subsequently weaned off LVAD support. The only case of pre-transplant LVAD that died was a case of hypertrophic cardiomyopathy with a relatively small LV size, where the inflow cannula was placed in the right superior pulmonary vein, instead of LV apex, and outflow cannula in the ascending aorta. This 1 case eventually succumbed pre-transplant, with multisystem organ dysfunction.

A total of 2 patients required post-transplant isolated temporary RVAD support due to right ventricular primary graft dysfunction. Both patients were successfully weaned off the RVAD within 10 days of implantation.

A VAD with a membrane oxygenator in a Koji-VAD configuration was utilized in 4 cases. The Koji-VAD was utilized pre-transplant in all the 4 cases. Of the total 4, one died pre-transplant due to septic shock.

Primary outcome

Of the total cohort of 35 patients, 17 patients (48.5%) encountered the primary endpoint of in-hospital mortality. Out of these total 17 mortalities in this study group, 10 patients had MCS instituted pre-transplant and 6 had post-transplant, while one patient had both. Out of these 10 pre-transplant MCS-related mortalities, 9 patients (81.8%) died on the waiting list, while 1 patient died despite being bridged to cardiac transplant. Of 11 patients who had post-transplant MCS, 6 (54%) died. Two patients required MCS, pre- and post-transplant, of which one had in-hospital mortality.

Furthermore, to analyze our outcomes in the context of the severity of the presenting illness, we also stratified our cohort based on the patient’s INTERMACS profile [2], at the time of index admission for MCS (Fig. 2). As anticipated, a majority of our patients were INTERMACS profile 1 (16 out of 35, 45.7%) and INTERMACS profile 2 (9 out of 35, 25.7%) on the first presentation for transplant. Among the 17 mortalities, the majority belonged to INTERMACS profile 1 (9 out of 17) and profile 2 (4 out of 17) (Fig. 3).

Fig. 2.

Stratification of the total cohort of 35 patients according to INTERMACS profile at the time of first presentation

Fig. 3.

Outcomes-based on INTERMACS profile at the time of admission

Secondary outcomes

MCS-related vascular injury or limb ischemia, as defined above, was observed in 9 out of the total of 35 patients (25.7%). Two of these patients required femoral artery repair. None of the patients required amputation or fasciotomy. Between 2015 and early 2017, we had observed 2 instances of MCS-related peripheral vascular injury, resulting in severe hemorrhagic shock, eventually leading to death. Both these patients developed external iliac artery rupture during arterial cannulation for MCS, leading to large retroperitoneal hematoma. Both these patients had atheromatous iliac arteries, which would have been noted on vascular ultrasound study. With the incorporation of routine vascular ultrasound screening, these vascular injuries were no longer encountered. No instance of stroke/transient ischemic attack or mechanical pump or circuit dysfunction was observed.

Furthermore, 4 out of the 35 patients (11%) developed pulmonary edema or hemorrhage on the VA-ECMO circuit. One of these patients underwent atrial septostomy to vent the left heart while the other 3 patients on VA-ECMO were converted to a Koji-VAD configuration by the addition of a LV apical vent, via lateral thoracotomy approach. One patient on temporary LVAD had severe right heart failure and was converted to Koji-VAD by central cannulation of the right atrium.

Discussion

There are no major guidelines about temporary MCS implantation in the setting of acute cardiogenic shock. Over time, all the advanced heart failure and cardiac transplant centers have developed their protocols, based on their own anecdotal experiences and results from registry-based publications [2, 4]. Furthermore, there is a dearth of publications on the clinical outcomes of temporary MCS from outside the Western world.

This single-center, retrospective study demonstrates a 48.5% in-hospital mortality in patients with advanced heart failure listed for cardiac transplant and requiring MCS. Moreover, the in-hospital mortality was markedly better in patients that eventually received a cardiac transplant, thus demonstrating how astute MCS implementation has improved waitlist mortality. We also noted a reduction in MCS-related peripheral vascular complications, as we refined our protocols over the years, and developed standard operating practices at our institute.

Low organ donation rates, late referrals for heart transplant, and sudden deterioration to INTERMACS profiles 1 or 2 in these patients edified us to prepare for MCS at any time.

Selected patients in INTERMACS profiles 3 and 4 with marginally high pulmonary vascular resistance (PVR) were managed with home-based Milrinone infusion, to reduce repeated hospitalizations, to decrease pulmonary vascular resistance, and to further reduce sudden decompensation needing MCS before transplant.

In the initial stages of the program, until early 2017, we observed high waitlist mortality. This was largely due to late referrals and a limited variety of MCS devices at our disposal. After procuring the CentriMag® pump, the number of MCS implantations increased, vis a vis a reduction in the total mortality (Fig. 4). Furthermore, with axillary artery cannulation and CentriMag®, we were able to maintain clinical stability for a longer duration, with lesser complications and early mobilization.

Fig. 4.

Year-wise mechanical circulatory support (MCS) and related mortality

All the 24 patients, who had pre-transplant MCS, belonged to INTERMACS 1 or 2 profiles. Among these 24 patients, 12 were bridged to transplant. All but 2 of these 12 patients survived the index hospitalization, thus accounting for a 90% survival among this selective high-risk cohort. The remaining 12 out of the 24 patients could not be bridged to transplant. Non-availability of donor organ in time, continuous deterioration of patients on MCS, sepsis, DIC, gastrointestinal bleed, and intrapulmonary hemorrhage were major causes of mortality in these patients. The difference in mortality among the patients on pre-transplant temporary MCS, who got transplanted and those who could not, is significant (p = 0.0379) (Fig. 5).

Fig. 5.

Survival of mechanical circulatory support (MCS) bridged to transplant vs. no transplant

VA-ECMO was used in a total of 20 cases (57%) (Table 1). It has been the mainstay modality of treatment in our program. ECMO is easily available, quick to implement, provides biventricular support and oxygenation, and allows easy transportation.

IABP is used in selected ischemic cardiomyopathy patients as an emergency assist device. Patients with increased preload, high pulmonary vascular resistance, biventricular decompensation, and renal failure did not improve with IABP alone. Additional MCS was then needed, in the form of ECMO or Koji-VAD (Table 2). In post-transplant patients with significant primary graft dysfunction, while weaning off cardiopulmonary bypass (CPB), IABP was used as a bridge to decision or bridge to recovery.

Bridge to recovery often happens when the insult is acute in a previously normal heart. This small cohort of patients, who recovered enough native cardiac function, had acute myocarditis or peripartum acute myocardial dysfunction. In such a subset of patients, it is desirable to institute MCS earlier or “on time” to get the best outcome as temporary MCS often aids in completely recovery by unloading the struggling ventricle.

Timing of intervention

The timing of temporary MCS and appropriate patient selection are the keys to the success of any MCS program. Although pharmacotherapy allows optimization of hemodynamics and decongestion of the lungs, liver, and kidneys, attempts at optimization should not further delay institution of temporary MCS. MCS has limited ability to change outcomes if initiated when multiorgan dysfunction has already developed. MCS should not be considered the treatment of last resort, but should probably be initiated earlier in the cardiogenic shock spectrum (INTERMACS 2 instead of INTERMACS 1).

Choosing MCS devices

In the last two decades, there are many temporary MCS devices available with various options for treating HF patients presenting in various settings [4]. These devices vary significantly in their primary hemodynamic support and secondary responses, as illustrated in Table 3. The ideal device should be able to provide hemodynamic support to all vital organs. It should unload the critically damaged ventricle by either afterload or preload reduction. Also, a percutaneous approach is preferable to provide for quick and easy deployment in emergent “crash” situations. Besides, the device should be associated with a low complication rate [5, 6].

Table 3.

Mechanical circulatory support devices and their hemodynamic effects

	IABP	ECMO	LVAD
Afterload	↓	↑↑	↑
LVEDP	↓	↑	↓↓
LVESV	↓↓	↑	↓↓
PCWP	↓	↑	↓↓

IABP, intra-aortic balloon pump; ECMO, extracorporeal membrane oxygenator; LVAD, left ventricular assist device; LVEDP, left ventricular end diastolic pressure; LVESV, left ventricular end systolic volume; PCWP, pulmonary capillary wedge pressure

Major prime drivers in the selection of the type of temporary MCS in any setup are hemodynamics of critical patients, state of vital organs, availability of MCS devices, circumstances at the time of institution, and economic feasibility. The modality should be point driven to support all hemodynamic parameters, is easy to institute in any given circumstance, is cost-effective, and aids easy conversions (if needed) to other modalities of MCS, to support changing hemodynamics (Fig. 5). The rates of device-related complications such as limb ischemia, access site bleeding, hemolysis, and infection can be reduced by appropriate planning in all waitlist patients. The choice of device is of great importance, as it may modify the systemic response to the primary cardiac injury and thus reduce multiorgan dysfunction [7].

The utility of transoesophageal echocardiography

All the patients, who had MCS inserted at our center, had intraprocedural TEE and ultrasound-assisted percutaneous cannulation. TEE is a frontline modality during the implantation of MCS. Pre-procedural assessment of biventricular function; the aortic, mitral, and tricuspid valves; intracardiac shunt; the ascending aorta; the interatrial and interventricular septa; and intracardiac thrombus/clots helps in deciding MCS device. During the surgical procedure, it enables accurate location and positioning of the guidewire and cannulae. In temporary LVAD, the positioning and direction of the LV apical cannula are very important and are guided by TEE [8]. As described earlier in the Methods section, TEE is extremely useful during MCS weaning when the pump speeds are gradually reduced and imaging is performed to evaluate native LV/RV function and severity of mitral/tricuspid regurgitation.

Reducing MCS-related vascular injury

Initially, we had few vascular complications while instituting ECMO, which manifested in developing a standard operating protocol for all patients being registered for transplant. Since mid-2017, detailed peripheral ultrasound vascular study, during the pre-transplant period, facilitated us in advance planning in the judicious selection of cannulation sites and sizes of the cannula. This eased the insertion of MCS cannula during eCPR of these waitlist patients. Additionally, in peripheral VA-ECMO, a distal perfusion cannula is always used. We have seen a decreasing trend in the incidence of accidental vascular injuries and limb ischemia, as mentioned above in the section on secondary outcomes [9, 10].

Over the years, our ECMO cannulation policies have evolved. At the beginning of the program, all ECMO cannulations were femoral artery–femoral vein, in the same or different leg. Now, we use that approach for cannulation only in eCPR or ECMO at the peripheral center before transportation. Whenever the patient is relatively stable to institute ECMO in the operating room at our center, we now prefer axillary artery outflow cannulation. Axillary artery cannulation is thought to blunt the afterload increasing effect, expected with femoral outflow cannulation, thus avoiding complications like pulmonary edema and hemorrhage on VA-ECMO [3, 11]. Axillary artery cannulation also helps ensure oxygenated perfusion of the upper limbs, thus reducing the chances of developing north-south syndrome/Harlequin syndrome. With axillary artery cannulation and the versatility of the CentriMag® pump, conversion from one MCS modality to another is quick and life-saving, and is done through a small left thoracotomy (Fig. 6) [12]. The same axillary cannula can then be used as an arterial line at the time of transplant.

Fig. 6.

Demonstrating modality, device, cannulation site, which device, and when. eCPR, extracorporeal membrane oxygenator during cardiopulmonary resuscitation; RV, right ventricle; LV, left ventricle; ECMO, extracorporeal membrane oxygenator; PVR, pulmonary vascular resistance; VAD, ventricular assist device; LVAD, left ventricular assist device

In patients with primary LV dysfunction, without significant RV impairment needing MCS, temporary LVAD is a better choice, if the patient is stable to plan the procedure. It allows a longer duration of support and avoids complications of membrane oxygenator. Temporary CentriMag® LVAD with axillary cannulation also allows for faster mobilization as shown in Table 4. Usage of CentriMag® RVAD in cases of post-transplant primary graft dysfunction was also successful in saving the lives of transplanted patients, as a bridge to recovery. The CentriMag® pump is designed to decrease hemolysis and thrombus formation by employing magnetic levitation and bearing-less technology. This allows minimal friction and thermal energy generation during operation. It also provides higher flows at fewer revolutions [12, 13].

Table 4.

Comparison of mechanical circulatory support devices

Type of MCS	Primary ventricle		LV unloading	Mobilization on support	Duration of support+
	LV	RV
IABP	++	–	Yes	No*/limited	10–15 days
ECMO	+	+++	No	No*/limited	2–3 weeks
LVAD	++++	+	Yes	Yes	4–6 weeks

*Femoral cannulation

+ Experience of the center

MCS, mechanical circulatory support; IABP, intra-aortic balloon pump; ECMO, extracorporeal membrane oxygenator; LVAD, left ventricular assist device; LV, left ventricle; RV, right ventricle

Limitations

The study has limitations given the small size and retrospective design, and represents a single-center experience. The study results reflect the patient referral patterns, scarcity of deceased organ donors, and community acceptance of MCS and transplant in western India. However, designing a randomized, controlled study in such a cohort of patients may be considered unethical. Furthermore, collating multicenter experience may be subjected to bias given technical expertise of the team at each center.

Conclusion

The timely introduction of temporary MCS in high-risk HF patients, bridged to cardiac transplant, can change the outcomes in these unpredictable patients. Routine pre-transplant thorough vascular ultrasound assessment can help in advance planning of MCS cannulation strategies, thereby reducing incidence of MCS-related vascular complications. CentriMag® LVAD offers flexibility, options, and prolonged duration of support in pre- and post-heart transplant patients.

Funding

No funding was required for the study.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Informed consent

Consent waiver was obtained from the ethics committee in view of retrospective nature of study.

Statement on welfare of humans

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Statement on welfare of animals

This article does not contain any studies with animals performed by any of the authors.

Ethics committee approval

Approval from the ethics committee has been obtained.