Senior Staff Writer

EVAR advantages drop over time

Catheter-based endovascular repair (EVAR) has clear benefits over open surgical repair for abdominal aortic aneurysm (AAA) patients, but the survival advantage of EVAR over open repair decreases over time, according to a new study. Researchers at Beth Israel Deaconess Medical Center (BIDMC; Boston) found that EVAR is safer and provides a quicker recovery compared to open repair, but after eight years, survival rates for the two groups were virtually even. The study was published July 22 in The New England Journal of Medicine. Despite early survival benefits such as lower mortality rate at 30 days (1.6% compared to 5.2%), fewer complications, and shorter hospital stays, the researchers said aneurysm rupture occurred in 5.4% of EVAR patients who survived for eight years versus 1.4% of patients who received open repair. The authors suggested patients should come back for follow-up after endovascular surgery and undergo additional interventions, if needed, to prevent late rupture.

CDT case volume linked to better outcomes

Higher institutional case volume is associated with improved outcomes for catheter-based blood clot removal in patients with deep vein thrombosis (DVT) of the legs - also referred to as catheter-directed thrombolysis (CDT) – compared to treatment with anticoagulation alone, according to researchers at Temple University Hospital (Philadelphia). Despite its benefits, however, CDT has been shown to be associated with increased bleeding complications, the researchers said. The study was designed to find out if those increased bleeding complications were correlated with the volume of CDT procedures performed at a particular institution. They found that a higher volume of CDT cases annually was associated with lower in-hospital mortality rates and lower intracranial hemorrhage rates. The study was published online in Circulation. Centers that performed six or more CDT procedures a year were considered high volume centers.

Texas Children's revises donor wait list protocols

A team at Texas Children's Hospital (Houston) said they have cut wait times by revising the hospital's heart transplant wait list protocols to focus on donor heart size and patient severity status. Patients at Texas Children's had a median wait time of 128 days in 2013, the team reported. Before the initiative, 19 patients had already been on the wait list and had been waiting for a median of 181 days. After a change in the size parameter, a status appeal, or both, these patients only waited an additional 56 days to receive a donor heart.

Researchers develop template
for growing human heart

A new template for growing beating cardiac tissue from stem cells could serve as a model for early heart development and a drug-screening tool to make pregnancies safer. Researchers at the University of California, Berkeley (UC Berkeley) and the Gladstone Institutes (San Francisco) said they developed the template using biochemical and biophysical cues to prompts stem cells to differentiate and self-organize into micron-scale heart tissue, including microchambers. The research was published July 14 in the journal Nature Communications.

According to the researchers, this may be the first example illustrating the process of a developing human heart chamber in vitro. They said the technology could help them quickly screen for drugs likely to generate cardiac birth defects, and guide decisions about which drugs are dangerous during pregnancy.

To test the potential of the system as a drug-screening tool, the researchers exposed the differentiating cells to thalidomide, a drug known to cause severe birth defects. They found that at normal therapeutic doses, the drug led to abnormal development of microchambers, including decreased size, problems with muscle contraction and lower beat rates compared with heart tissue that had not been exposed to thalidomide.

The development comes about four months after UC Berkeley researchers debuted a system of beating human heart cells on a chip that could be used to screen for drug toxicity. However, that heart-on-a-chip device used pre-differentiated cardiac cells to mimic adult-like tissue structure, they noted. In the new study, the scientists mimicked human tissue formation by starting with stem cells genetically reprogrammed from adult skin tissue to form small chambers with beating human heart cells. Gladstone, an independent, nonprofit life science research organization affiliated with UC San Francisco, supplied the human induced pluripotent stem cells for the study. The undifferentiated stem cells were then placed onto a circular-patterned surface that served to physically regulate cell differentiation and growth. By the end of two weeks, the cells that began on a two-dimensional surface environment started taking on a 3-D structure as a pulsating microchamber, the scientists reported. Moreover, the cells had self-organized based upon whether they were positioned along the perimeter or in the middle of the colony.

The team also said there is potential to use the technology to study other organ development as well as heart tissue.

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