The National Heart Centre Singapore (NHCS) has introduced a new, smaller and lighter mechanical heart pump for advanced heart failure patients that will allow them to enjoy a better quality of life and functional capacity while waiting for a heart transplant. The new heart pump, known as HeartWare ventricular assist device (HVAD), is the third generation of mechanical heart devices. The golf ball-sized device fits entirely in the pericardial space above the diaphragm in the patient. The previous generation of such devices required a small pocket to be surgically created below the heart to fit the mechanical pump.

Madam Helen Tan, 57, was the first patient in Singapore to be implanted with the HVAD on 26 September 2012. The NHCS surgical team led by Associate Professor Lim Chong Hee, Senior Consultant, Department of Cardiothoracic Surgery and Director, Heart and Lung Transplant Programme, NHCS performed the 4-hour open heart surgery. Madam Tan was discharged well after 19 days of hospitalisation on 15 October 2012.

“Before I had the HVAD pump implanted, I was always out of breath, tired and so weak that I could hardly walk and go about with my daily life,” recounted Madam Tan who has been living with heart failure since 2006, “Now that I have this heart pump, I can get back to my normal routine and help look after my grandchildren.” Madam Tan has dilated cardiomyopathy where her heart becomes weakened and enlarged and is unable to pump enough blood to the rest of the body. Her heart was functioning at only about 25 to 30 per cent. A normal heart functions between 55 and 70 per cent. 

“The new HVAD pump’s miniature size allows it to be implanted at the apex of the heart’s left ventricle within the lining sac which envelopes the heart, also known as the pericardium,” said Associate Professor Lim, “This removes the need for creation of a pocket below the heart for placement of older devices.”

Results of the use of HVAD as a bridge to heart transplantation in patients with advanced heart failure were shown in a major US clinical trial (ADVANCE trial). The study compared 140 HVAD patients at 30 US hospitals with 499 patients on other left ventricular assist devices and registered in the INTERMACS (Interagency Registry for Mechanical Assisted Circulatory Support) system from August 2008 to February 2010. The overall 180-day success and survival rates for both groups are comparable at around 90 per cent. The HVAD group showed improvements in quality of life and functional capacity similar to that seen in patients with heart transplantations. It also had a favourable adverse event profile. Key adverse events included bleeding, infection and stroke.

“The HVAD was first implanted worldwide in Austria in March 2006, and clinical trials have proven its viability as a bridge to transplant or recovery for advanced heart failure patients,” said Dr C Sivathasan, Co-Director, Heart and Lung Transplant Programme, NHCS, “To date, more than 2,500 patients have been implanted with the HVAD pump and, based on its promising track record, we decided to offer it as an alternative option to our patients at NHCS

who are waiting for a heart transplant.”

Weighing just 160g, the HVAD pump is made of titanium composite materials and runs on a virtually frictionless system with no points of mechanical contact. Blood is pumped through the heart, from the left ventricle to the aorta, in a continuous flow via an electromagnetically suspended impeller that spins without the help of any ball bearings.

Madam Tan now wears equipment weighing about 2.5 kilograms to sustain her heart function: a controller and two batteries connected to the heart pump with a driveline cable which exits her body near the abdomen, as well as two spare batteries.

According to Dr David Sim, Consultant, Department of Cardiology, and Co-Director, Heart Failure Programme, NHCS, heart failure is the one of the most common cardiac conditions.

“Heart failure accounts for about 5,000 hospital admissions a year,” said Dr Sim, “At NHCS, we receive an average of 23 referrals a year for heart transplant. The lack of suitable donors is a key challenge. As a result, about one third of these cases require device implantation as a bridge to heart transplant”.

NHCS performs an average of three heart transplants yearly. To help bridge the gap to the limited donor pool, NHCS set up the Mechanical Heart Device Programme in 2001 to provide patients with advanced heart failure a means to prolong and improve their quality of life while waiting for a suitable donor heart. It is through the programme that new technology, such as the miniature HVAD pump, are made available as treatment options for these patients. To date, NHCS has performed 63 mechanical heart device implantations.

 

The National Heart Centre Singapore (新加坡国家心脏中心) is a 185-bed national and regional referral centre for cardiovascular diseases. It provides one-stop comprehensive preventive, diagnostic, therapeutic and rehabilitative cardiac services for heart patients.