HeartMate 3 Left Ventricular Assist Device Implantation in a Pediatric Patient With Limb-Girdle Muscular Dystrophy

CASE REPORT

A 16-year-old male with muscular dystrophy and 2 years of known cardiomyopathy presented to another facility with decompensated heart failure. The presentation was his second heart failure admission in 3 months despite optimal medical therapy as an outpatient, including home losartan (50 mg daily), furosemide (20 mg daily), carvedilol (6.25 mg twice daily), and aspirin (81 mg daily). He had experienced progressive dyspnea and fatigue for a few weeks. Based on echocardiography, the patient's ejection fraction had declined from 25% to 30% 3 months prior to approximately 10%. He was treated with inotropic support with milrinone and aggressive diuresis with intravenous furosemide, resulting in a 9 kg weight loss over the course of 1 week prior to transfer to our facility for consideration of advanced therapies including an LVAD.

The patient was evaluated by our pediatric advanced heart failure team that includes a social worker, psychologist, physical and occupational therapist, nutritionist, and palliative medicine physician. Given the patient's LGMD, Pediatric Neurology, Pulmonology, Genetics, and Physical Medicine and Rehabilitation were also consulted. Our Neurology and Genetics colleagues provided important evaluation and prognostic information regarding the patient's LGMD, Pulmonology assessed his baseline respiratory function and provided recommendations to maximize his respiratory function, and Physical Medicine and Rehabilitation formulated and implemented a rigorous rehabilitation program.

The most important factors to determine prior to considering the patient's suitability for implantation of a durable VAD were his long-term prognosis related to progression of the LGMD and the severity of his current levels of impaired mobility and respiratory function. During the prior year, the patient had experienced progressive limitations in mobility, necessitating the use of a walker and frequent use of a wheelchair for daily activities. His respiratory symptoms were confounded by his severe heart failure, but he had not required positive pressure ventilation, and his pulmonary function tests demonstrated a moderately restrictive pattern. No question existed regarding the short-term benefits the patient would receive from a VAD, but it was important to determine that a reasonable expectation existed for a legitimate long-term benefit. In the short term, the patient was not considered a candidate for cardiac transplant primarily because of the degree of his mobility impairment and the rate of progression. The possibility for assessment for transplant candidacy would remain open in the future once the patient was well enough and an assessment of his limits related to muscular dystrophy could be more clearly distinguished from the sequelae of his heart failure.

The multidisciplinary team decided to proceed with LVAD implantation as the device would increase the patient's cardiorespiratory function and improve his quality of life. The implant would be performed as a bridge to decision for cardiac transplant. A comprehensive postoperative rehabilitation plan was prepared.

Cardiac catheterization was performed prior to implantation to further assess the severity of the patient's at-least-moderate right ventricular dysfunction that was demonstrated on echocardiogram. Echocardiogram demonstrated normal valvular structures with moderate mitral insufficiency. At the time of catheterization, the patient was administered 0.5 μg/kg/min of milrinone and 0.02 μg/kg/min of epinephrine. His heart rate was 124 beats per minute, and his blood pressure was 125/78 mm Hg. The catheterization demonstrated dilated cardiomyopathy with low cardiac output and moderate pulmonary hypertension but indicated a low risk for the necessity of temporary right ventricular support as detailed by the following hemodynamic data: cardiac index 1.8 L/min/m² (body surface area 1.56 m²; weight 46.8 kg); cardiac output 2.8 L/min; right atrial pressure 12 mm Hg; right ventricular pressure 62/12 mm Hg; pulmonary artery pulsatility index 4.2; right ventricular stroke work index 6.35 g/m/beat/m²; pulmonary artery pressure 62/34 mm Hg (mean 44 mm Hg); pulmonary capillary wedge pressure 38 mm Hg; and pulmonary vascular resistance of 3 Wood units. A CardioMEMS device (Abbott Cardiovascular) was placed at the time of cardiac catheterization to allow outpatient monitoring of the patient's pulmonary pressures and help fine-tune his VAD settings and diuretic regimen postoperatively.

The patient was determined to be an appropriate surgical candidate, and on hospital day 5, he underwent implantation of a HeartMate 3 LVAD (Abbott Cardiovascular). The operation was uncomplicated, and the patient was weaned from bypass on typical inotropic support and inhaled nitric oxide for right ventricular support. His postoperative course was unremarkable. He was extubated on postoperative day 1 and did quite well with the expected additional support needed from Physical and Occupational Therapy that worked aggressively to mobilize him early and often with inpatient physical rehabilitation. He was weaned from all inotropic and inhaled nitric oxide support by postoperative day 4. Echocardiogram demonstrated normal right ventricular size with moderately decreased systolic function. He was discharged on postoperative day 16 in substantially improved cardiorespiratory condition, although he was still using a walker and wheelchair as he had been prior to surgery.

Upon discharge, the patient was enrolled in cardiac rehabilitation and outpatient physical and occupational therapy, and he was scheduled for regular clinic visits. At follow-up 3 months after discharge, he reported substantially increased endurance. He was able to complete activities of daily living independently and was no longer using the wheelchair.