Clinical course and outcome after treatment with ventricular assist devices in paediatric patients: A single-centre experience.

BACKGROUND: Heart failure is a rare condition in the paediatric population, associated with high morbidity and mortality. When medical therapy is no longer sufficient, mechanical circulatory support such as a ventricular assist device can be used to bridge these children to transplant or recovery. Coagulation-related complications such as thrombi, embolism and bleeding events represent the greatest challenge in paediatric patients on mechanical support. We aimed to describe the outcomes and coagulation-related complications in this patient population at our institution. METHODS: A total of 20 patients with either Berlin Heart EXCOR® or HeartWare® implantation were reviewed in this retrospective study. Study endpoints were survival to heart transplant, weaning due to recovery or death. Thrombotic events were defined as thrombus formation in the device or in the patient, or cardioembolic strokes. Bleeding events were defined as events requiring interventional surgery or transfusion of red blood cells. RESULTS: The aetiology of heart failure included cardiomyopathy (n = 12), end-stage congenital heart disease (n = 6) and myocarditis (n = 2). Of the 20 patients, 12 were bridged to transplant, 7 recovered and could be weaned and 1 died. The median duration of mechanical support was 84 days (range: 20-524 days). At least one major or minor bleeding event occurred in 45% of the patients. Thrombotic events occurred 21 times in 10 patients. Four of the patients (20%) had no bleeding or thromboembolic event. CONCLUSION: In all, 95% of the patients were successfully bridged to transplant or recovery. Bleeding events and thrombotic events were common.

Durable circulatory support with a paracorporeal device as an option for pediatric and adult heart failure patients.

OBJECTIVES: Not all patients in need of durable mechanical circulatory support are suitable for a continuous-flow left ventricular assist device. We describe patient populations who were treated with the paracorporeal EXCOR, including children with small body sizes, adolescents with complex congenital heart diseases, and adults with biventricular failure. METHODS: Information on clinical data, echocardiography, invasive hemodynamic measurements, and surgical procedures were collected retrospectively. Differences between various groups were compared. RESULTS: Between 2008 and 2018, a total of 50 patients (21 children and 29 adults) received an EXCOR as bridge to heart transplantation or myocardial recovery. The majority of patients had heart failure compatible with Interagency Registry for Mechanically Assisted Circulatory Support profile 1. At year 5, the overall survival probability for children was 90%, and for adults 75% (P = .3). After we pooled data from children and adults, the survival probability between patients supported by a biventricular assist device was similar to those treated with a left ventricular assist device/ right ventricular assist device (94% vs 75%, respectively, P = .2). Patients with dilated cardiomyopathy had a trend toward better survival than those with other heart failure etiologies (92% vs 70%, P = .05) and a greater survival free from stroke (92% vs 64%, P = .01). Pump house exchange was performed in nine patients due to chamber thrombosis (n = 7) and partial membrane rupture (n = 2). There were 14 cases of stroke in eleven patients. CONCLUSIONS: Despite severe illness, patient survival on EXCOR was high, and the long-term overall survival probability following heart transplantation and recovery was advantageous. Treatment safety was satisfactory, although still hampered by thromboembolism, mechanical problems, and infections.

Clinical Durability of the CARMEDA BioActive Surface in EXCOR Ventricular Assist Device Pumps.

The durability of CBAS Heparin Surface on EXCOR pumps retrieved after clinical use for varying periods of time was studied by analyzing samples for surface heparin density and bioactivity. The mean time of clinical use of the investigated 14 EXCOR pumps was 178 days (range, 15-461 days). Mean heparin density was 3.1 ± 0.6 µg/cm² (range, 2.2-4.8 µg/cm²), and the measured mean heparin bioactivity was 14 ± 5 ρmol/cm² (range: 7-27 ρmol/cm²). There was no detectable degradation or loss of function of CBAS Heparin Surface over time. Samples from the housing and the membrane of the EXCOR pump showed no significant difference in heparin bioactivity or density. The CBAS Heparin Surface stays on the surface and remains bioactive on the EXCOR pump at least up until 1 year. This is an important demonstration of coating durability and supports the mid-term and long-term clinical use as bridge-to-heart transplantation or to myocardial recovery.

Minimally invasive insertion of an equine stented pulmonary valve with a built-in sinus portion in a sheep model.

OBJECTIVES: This study evaluated the feasibility of inserting a new equine stented-valve with a sinus portion in a lamb survival model, through a minimally invasive thoracotomy with right ventricular access without cardiopulmonary bypass. BACKGROUND: Extant surgical or percutaneous methods for inserting biological valves in the right outflow tract have drawbacks and limitations. METHODS: A decellularized equine valved jugular vein, sutured to a self-expanding stent with a sinus portion, was placed through a minimal right thoracotomy using a newly developed flexible hydraulic release device in seven lambs. The approach through the right ventricle into the pulmonary valve position is achieved on a beating heart. RESULTS: The stented valves were correctly positioned in the right outflow tract, were competent up to 6 months as confirmed by angiography and echocardiography, and were well-tolerated by the animals, with endothelialization of the valve demonstrated at 6 months. CONCLUSIONS: The newly developed hydraulic release system allowed for safe and reliable insertion of an equine stented-valve with a sinus portion, through a right transventricular approach on a beating heart, in a sheep survival model.

A study of the physiological consequences of sympathetic denervation of the heart caused by the arterial switch procedure.

BACKGROUND: The arterial switch operation is the corrective operation for transposition of the great arteries, defined as the combination of concordant atrioventricular and discordant ventriculo-arterial connections, but there have been concerns about silent subendocardial ischaemia on exercise and coronary artery growth. The arterial switch divides the majority of the sympathetic nerves entering the heart; we have studied the effects of coronary flow and sensitivity to catecholamine stimulation in an animal model. METHODS: A total of 10 piglets were operated on cardiopulmonary bypass with section and resuturing of aortic trunk, pulmonary artery and both coronary arteries, with 13 sham-operated controls. After 5-7 weeks of recovery, seven simulated switch survivors and 13 controls were studied. RESULTS: Basal heart rate was significantly higher in switch piglets: in vivo mean (standard deviation) 112 (12) versus sham 100 (10) beats per minute, (p = 0.042); in vitro (Langendorff preparation): 89 (9) versus sham 73 (8) beats per minute (p = 0.0056). In vivo maximal heart rate in response to epinephrine was increased in switch piglets, 209 (13) versus 190 (17) beats per minute (p = 0.044). In vitro dose-response curves to norepinephrine were shifted leftward and upwards (p = 0.0014), with an 80% increase in heart rate induced by 0.095 (0.053) norepinephrine micromole per litre perfusate in switch hearts versus 0.180 (0.035) norepinephrine micromole per litre (p = 0.023). Increase in coronary flow on norepinephrine stimulation and maximal coronary flow were significantly reduced in switch hearts: 0.3 (0.2) versus 0.8 (0.4) millilitre per gram heart weight (p = 0.045) and 2.5 (0.4) versus 3.1 (0.4) millilitre per gram heart (p = 0.030), respectively. CONCLUSIONS: A combination of increased intrinsic heart rate, increased sensitivity to chronotropic actions of norepinephrine, and a decreased maximal coronary flow creates potential for a mismatch between perfusion and energy demands.

Airway oximetry improves monitoring of dopamine effects in pediatric cardiac patients.

OBJECTIVE: Simple, preferably noninvasive measurements of cardiac output are useful in pediatric patients receiving inotropic support. Oxygen saturation in pulmonary artery (Svo(2)) gives information about oxygen delivery and demand. Many inotropic drugs influence oxygen consumption. When effects on Svo(2) are studied, after a change in inotropic drug dosage, a change in oxygen consumption needs to be considered to accurately estimate the change in cardiac output. The aim of this investigation was to study whether information on inspired to end-tidal oxygen concentration difference (Fi-eto(2)) in addition to Svo(2) would improve estimation of changes in cardiac output. DESIGN: Prospective observational study of Fi-eto(2), Svo(2), and oxygen saturation from central vein (Scvco(2)) for measurements of circulatory and metabolic effects of changes in dopamine dosage. SETTING: Intensive care unit in a children's hospital. PATIENTS: Twenty patients (age 4 days to 98 months) were studied after cardiac surgery. INTERVENTIONS: Dopamine was administered in doses of 5, 10, 0, and 5 microg x kg(-1) x min(-1), 20 mins on each level. MEASUREMENTS AND MAIN RESULTS: Cardiac output, measured with thermodilution, oxygen saturation from systemic artery (Sao(2)), Svo(2), and Scvco(2) were measured at 15 mins on each dopamine dose. Oxygen consumption was calculated by using the Fick equation. Fi-eto(2) was measured continuously with a paramagnetic oxygen analyzer. Both cardiac output and oxygen consumption were affected by changes in dopamine dosage. Relative changes in cardiac output were poorly correlated to the change in 1/Sa-vo(2) (r(2) =.54). Using Fi-eto(2) improved correlation between changes in cardiac output and changes in Fi-eto(2)/Sa-vo(2) (r(2) =.72). When Svo(2) was replaced by Scvco(2), the correlation between changes in cardiac output and changes in Fi-eto(2)/Sa-cvco(2) was only slightly altered (r(2) =.69). CONCLUSIONS: Dopamine affects oxygen consumption as well as cardiac output. The accuracy of Svo(2)-based estimations of changes in cardiac output after dopamine is enhanced if changes in Fi-eto(2) are also considered. The more easily achievable Scvco(2) gave equivalent information as Svo(2).