Postcardiotomy left ventricular assistance device implantation in a child: brief considerations

Abstract

Mechanical circulatory support after congenital heart surgery is uncommon, but not unusual. Stunning of ischemic myocardium after cardiopulmonary bypass could occur due to many reasons. According to the literature, this complication is rare in our center, but some options about implantation of a postcardiotomy left ventricular assistance device (LVAD) in toddlers deserve attention. Furthermore, although the VAD has been a well-established therapy for larger adolescents and adult patients with advanced heart failure, current experience with the use of VAD for mechanical circulatory support in infants and young children with small body surface area is still limited.

• congenital
• left ventricle
• mechanical support
• inotropes

Introduction

Postcardiotomy myocardial stunning due to ischemia following cardiopulmonary bypass (CPB) is a rare occurrence in our center, after complex repair in congenital heart surgery; however, even in the literature, the rate of this complication is low but present. Left or biventricular failure after a major congenital heart surgery is a clear indication to implant a left ventricular assistance device (LVAD) in pediatric patients requiring hard ventricular support where inotropic drugs are not sufficient.

In the experience herein reported, we have implanted an LVAD in an 18-month-old female baby discharged after 3 h from ICU postoperatively, who had a cardiac arrest in the operation theatre (requiring going back for bypass after intervention) and in ICU, following a repair of partial atrioventricular canal with a long cleft of mitral valve and an atrial septal defect ostium primum, with a huge dislocation between the interatrial and interventricular septa plus an evident deformation of ventricular outflow tract. Indication for implantation has been a clear left ventricular failure by echocardiography, with severe heart insufficiency, requiring fast hemodynamic support 1–4.

Implantation technique

Through median sternotomy, we implanted a Rotaflow (Rotaflow MAQUET Cardiopulmonary AG, Hirrlingen, Germany) LVAD centrifugal pump between the ascending aorta and the upper superior right pulmonary vein. The choice 5 of cannulas has been a 90° right-oriented ‘Pacifico’ metal cannula of 20 Fr for the venous drainage and a Medtronic (Medtronic, Inc., Minneapolis, USA) DPL 12 Fr cannula for aortic inflow (Figs. 1–3). Cannulas were ensured on sites with self-holding tourniquet technique (by a tip handmade with a small piece of the tourniquet) and placed outside the mediastinum through previous sternotomy and covered with a surgical sternal membrane, to avoid hemodynamical breakdown by compression of sternum itself upon the myocardial anterior wall during LVAD. Duration of LVAD has been 136 h, and the recovery of the patient was complete and adequate postoperatively due to the surgery. The patient was taken off respiratory support at day 9 after surgery (day 3 after stopping LVAD) (Fig. 4). Neurological signs at brain computed tomography scan were absent.

Fig. 1.  aortic and left atrium access for LVAD on site.

Fig. 2.  External Membrane Skin closure with open chest during LVAD.

Fig. 3.  Chest XRays during LVAD.

Fig. 4.  Chest Xrays after weaning from LVAd and sternal closure.

Surgical procedure

Management of LVAD in ICU is never easy and needs a multidisciplinary approach for a successful outcome and often a dedicated team working in the same discipline 3. Adverse events are not rare and they need continuous monitoring (Tables 1 and 2).

Table 1.  Mechanical and patient related complications for respiratory population

	Neonatal	Pediatric	Adult
Mechanical
Oxygenator failure	5.7 (55)	13.8 (44)	18.2 (43)
Tubing rupture	0.7 (74)	3.8 (47)	4.0 (30)
Pump malfunction	1.8 (68)	3.1 (47)	4.1 (37)
Cannula problems	11.1 (70)	14.2 (48)	10.7 (42)
Patient related
Gl hemorrhage	1.7 (46)	4.0 (25)	4.3 (26)
Cannula site bleeding	6.1 (68)	9.2 (60)	11.5 (47)
Surgical site bleeding	6.1 (46)	16.0 (47)	22.4 (35)
Hemolysis	12.2 (68)	8.8 (42)	5.3 (28)
Brain death	1.0 (0)	6.0 (0)	3.8 (0)
Seizures: clinically determined	10.9 (62)	7.3 (35)	2.0 (45)

Table entries are in percentage reported (% survival). Gl, gastrointestinal.

Table 2.  Mechanical and patient related complications for cardiac population

	0–30 days	31 days and <1 year	1 year and <16 years	>16 years
Mechanical
Oxygenator failure	7.2 (23)	7.2 (28)	9.1 (37)	16.4 (27)
Tubing rupture	0.7 (31)	1.1 (24)	2.0 (30)	0.9 (20)
Pump malfunction	1.3 (32)	1.9 (26)	2.2 (42)	1.8 (36)
Cannula problems	6.7 (33)	5.9 (35)	6.4 (31)	6.8 (32)
Patient related
Gl hemorrhage	0.9 (5)	1.8(14)	2.8 (23)	2.4 (1 5)
Cannula site bleeding	6.8 (27)	6.7 (23)	10.7 (44)	12.9 (30)
Surgical site bleeding	31.0 (29)	33.9 (36)	31.3 (42)	31.9 (27)
Hemolysis	10.8 (24)	9.9 (33)	8.5 (35)	8.1 (34)
Brain death	1.3 (0)	5.1 (0)	9.5 (0)	7.9 (0)
Seizures: clinically determined	9.7 (29)	11.0 (24)	6.8 (21)	4.8 (12)

Gl, gastrointestinal.

From our perspective, we were required to manage a clear left ventricle failure after CPB surgery for a congenital heart disease in an 18-month-old baby, weighing 10 kg. We decided to perform a planned LVAD implantation between the ascending aorta and the left atrium via right upper pulmonary vein. We had preferred this approach to avoid handling the injured ventricle as a result of ischemia after bypass and also to avoid high perfusion pressures in case of use of left apical access during the course of LVAD, on the drainage cannula, especially during the weaning from machine and restoring of contraction.

Blood flow at the start of VAD (Fig. 5) was around 800–900 ml (over 1 L estimated flow) per hour with atrial left pressure of 4–6 mm Hg. We considered it to be an acceptable pitfall due, possibly, to a right ventricle failure associated with the left ventricle insufficiency in the early stages of LVAD. The duration of assistance was 136 h, and the ejection fraction of left and right ventricles was monitored every 8 h 2. We observed a decrease in enzyme amount during LVAD (Fig. 6), with a progressive recovery of ventricular function associated with a necessity to decrease LVAD flows step by step. Bleeding from cannula sites was not significant, and the total amount of bleeding from chest drainages was scarce. Adverse clotting events during circulation were not noticed, and anticoagulation range was maintained between 145 and 200 s activated clotting time and 70 and 90 s activated partial thromboplastin time.

Fig. 5.  Flow chart of VAD range during assistance.

Fig. 6.  Enzyme decrease during VAD

Anesthesiological and pharmacological procedure

Management and monitoring of inotropes are fundamental during the implantation of LVAD to support the circulation and function of right and left ventricles during the recovery. In the early phases of LVAD, we observed a decrease in right ventricular contraction, probably subsequent to a poor left ventricle functioning. Administration of NO (20 ppm), adrenaline, and noradrenalin up to 0.2 ɣ/kg/min was started at this time to ameliorate pulmonary resistances and support right venous blood flow back through the right ventricle. With continuation of LVAD, NO was progressively weaned and noradrenaline stopped at 40th hour of assistance. Drugs of choice in this phase were adrenaline, 0.1 ɣ/kg/min, sildenafil and milrinone, 0.70 ɣ/kg/min, until the patient reacquired a sinus rhythm (100th hour of VAD), and until a complete weaning and stopping of mechanical support were achieved. After that, adrenaline was stopped and milrinone infused at low dosage. So we could consider almost satisfactorily the pharmacological support of right ventricle, to let it join the left one until a complete recovery of the heart.

In 36th hour of assistance, a severe platelet loss occurred as a main adverse event. A platelet value of 11×10⁻³/µl, started with hemofiltration, was infused, but no blood loss was observed as a result of this. Heparin infusion was decreased to 20–30 UI/kg/H and platelet transfusion delayed to the 112th hour to manage a mild blood effusion from the sternum. Subsequently, bleeding continued to be not significant until LVAD was discontinued. Hemofiltration was targeted to 50 mL/h, despite spontaneous renal function was not deteriorating, with creatinine value in normal range. In our view, a novel event that we came across in this case management was the complete absence of curarization during LVAD.

Comments

Postcardiotomy extracorporeal circulation life support is a rare occurrence in our surgical practice for congenital diseases. LVAD is preferred over ECMO in terms of compliance due to bleeding or other events, like the survival for critical status of illness of ventricular myocardium, and centrifugal temporary pump 6 7 seems to add more advantages rather than pulsatile where single ventricular failure occurs 3 4 8 6.

Planned LVAD has showed, in our case, a successful course after myocardial ischemia following cardiotomy during CPB. We consider that it is appropriate to analyse the reasons leading to this kind of event to decide as fast as possible. The outcome of the toddler was complete, and weaning from LVAD was performed in association with monitoring of main parameters, such as SVO₂, ejection fraction of left ventricle, cardiac rhythm, arterial pressure, and venous left atrial pressure peak measurement for CO value; recovery was accomplished by achieving a decrease in cardiac enzymes and metabolic balance of the patient. Neither infection of the site nor general septic status was present. In our experience, the main pitfall of the procedure was the platelet count, which decreased at the 2nd day of the procedure, probably due to hemofiltration 9, but not leading to blood loss or other adverse events. Apical drainage of left ventricle could be advantageous in managing the right ventricular failure, but from the other side, handling a stunned and ischemic myocardium for cannula insertion could lead to further damages, and a higher pressure in the ventricle during the weaning from the VAD could lead to an excessive risk of bleeding at the site of insertion.

At that moment, the general status of the baby was compatible with a good postoperative recovery. Hypotony and hyporeflexia of left arm were present, and magnetic resonance neurography examination of brain showed a left temporal–occipital ischemic focus that configured a pattern of pediatric hypoxic–ischemic brain injury 10. On the other hand, we observed on day 8 after LVAD was discontinued, a 50% recovery of left arm and leg motion, with a progressive enhancement of neurological status in the following days. At 1-month follow-up, the recovery of the patient was complete and satisfactory from a neurological point of view.

In conclusion, the objective of LVAD implantation after myocardial injury following CBP is to consider the restoration of the left ventricle as fast as possible. Associated complications such as infections and brain injuries can occur 11, but accurate monitoring of coagulative status 12 and antibiotic therapy can prevent them. Plenty of options must be explored for brain injuries to be avoided as the next steps for a complete knowledge management.

Conflict of interest and funding

There is no conflict of interest in the present study for any of the authors.