Manufacturers of automated external defibrillators, especially those designated specifically for home use, were hit with negative study findings early this month, with a report that AEDs used at home provided no particular increase in surviving a heart attack of the sudden cardiac arrest (SCA) type.

According to an April 1 statement at the website for the National Institutes of Health, the recently completed Home Automated External Defibrillator Trial (HAT) — underwritten in part by NIH's National Heart, Lung and Blood Institute (NHLBI) — indicates that those at risk for SCA were as likely to survive when AEDs were not available at home as when they are.

NIH said that the HAT study "followed 7,001 heart attack patients at moderate risk of sudden cardiac arrest who had a spouse or other live-in companion." To enroll the patient, that spouse or companion had to agree to either deploy the AED or perform CPR in the event of cardiac arrest. After three years of follow-up, "researchers found that survival rates were about the same" between the two groups.

However, the NIH report says that "there were relatively few sudden cardiac arrests, and only 39% of those events were witnessed at home."

According to NIH, "at least 95% of cases [of sudden cardiac arrest] end in death within a few minutes," with 75% of such incidents taking place at home.

Of the study participants, all of whom had suffered a cardiac arrest previously, 450 died during the course of the study, an almost even split between the control group (228) and the AED group (222). However, only 160 of those deaths were due to sudden cardiac arrest. Unfortunately, about half (59) of those events took place when the patient was alone at home.

Gus Bardy, MD, the lead researcher for HAT, said that the prevailing theory was that "the vast majority of sudden cardiac arrests would happen at home, but we didn't expect that so few would be witnessed by a spouse or other member of the household." Bardy acknowledged that this "dramatically limits the chance that someone would be there to use an AED or to perform CPR."

The study also indicates that AED use in the home is perhaps less than optimal — a finding that runs counter to some studies showing that "bystanders" and those generally untrained in AED use, are able to operate the devices according to instructions and get good results. According to study co-author Eleanor Schron, PhD, co-author of the HAT study, instead cited a study that she said indicated that nearly twice as many patients survived cardiac arrest in communities where volunteers were trained in AED use, compared to communities where only CPR training took place.

Schron said that similar finding in HAT indicates that "AEDs were under-used in the home."

Volcano's s5 options offer integration of IVUS and FFR

Intravascular imaging of coronary arteries continues to be refined, allowing physicians to more accurately assess lesion severity and confirm proper stent placement. Although intravascular ultrasound (IVUS) and fractional flow reserve (FFR), both technologies that aid in this process, have long been available to augment angiography, systems were cumbersome and very few physicians had access. Volcano Therapeutics (San Diego) last month reported U.S. and European launch of the s5-Revo and s5-FFR options for its s5i integrated imaging platform, new product options that enable rotational IVUS and FFR to operate on the same integrated system.

FDA-approved in February, these options are intended to make the physician's job easier, and diagnosis and treatment more accurate.

"IVUS or FFR confirm that you need to treat in the first place," Volcano's Vince Burgess, executive VP of marketing and business development told Cardiovascular Devices & Drugs, saying that practitioners have been misled by using angiography alone to assess lesion severity and to confirm proper stent placement. "Right now with angiogram, some lesions are clearly obstructed, or not. I would estimate half of images on angiograms are equivocal or questionable. With IVUS or FFR, you can intervene, and use the wire or catheter to determine extent of disease with much greater accuracy."

Burgess said, "Previously, to get an FFR measurement you needed a dedicated box and proprietary software. Although the technology and data you get is well documented as being helpful, the use of this technology has been low around the world."

Volcano's combined technology does have a price barrier, with a price range of $75,000 to $125,000 per cath lab suite, suggesting it might take awhile to populate all interventional labs.

"IVUS use in the last two to three years has doubled from 7% to almost 15%," he said. "A key driver is the fact that all IVUS products — ours and our competitor's — are getting easier to use."

Boston Scientific's (Natick, Massachusetts) iLab Ultrasound Imaging System is Volcano's only competitor, Burgess said.

Earlier generation consoles included only one of the three technologies now available on the s5i. If a hospital wanted to equip a new lab with all three technologies, it would have to acquire three separate consoles, each with a different measurement modality, training requirements and data storage protocols.

Volcano reports that the s5i Imaging System has been tested in cooperation with GE Healthcare (Waukesha, Wisconsin), Philips Medical Systems (Andover, Massachusetts), Siemens (Munich, Germany) and Toshiba America Medical Systems (Tustin, California) for safety and compatibility when used with their current lines of X-ray systems and equipment.

Fresher blood found related to fewer cardiac surgical complications

A new study has found that cardiac surgery patients who received transfusions of blood that had been stored for two weeks or less had lower rates of complications and death than those who received blood that was older. The study is the work of researchers based at the Cleveland Clinic Foundation and published in the March 20 issue of the New England Journal of Medicine (NEJM).

The investigators compared 2,872 cardiac surgery patients who received transfusion blood that had been donated within the previous two weeks with 3,130 cardiac surgery patients who received transfusion blood that had been donated more than two weeks earlier.

They found that the patients who were given older blood had a higher risk of dying in hospital than their newer blood counterparts (2.8% vs. 1.7%), and they were significantly more likely to need prolonged ventilation support, have kidney failure or multiple organ failure.

Clinic investigators also discovered a direct "dose response" relationship between days of storage and the chances of a combination of serious complications or adverse events. After eliminating potential confounding factors, an analysis revealed that patients who had received older blood had a significantly higher rate of combined serious adverse events than those who received newer blood. Also, they found that patients who received newer blood had a higher chance of surviving the first year after surgery than those who received older blood 92.6% versus 89%).

A number of explanations have been offered to explain why older blood raises risks to patients. One is that stored blood loses nitric oxide, an important agent in the delivery of oxygen to tissue cells, and another is that red blood cells become more rigid and sticky as they age, making it difficult for them to squeeze through narrow blood vessels and raising the risk of a clot.

Editor-in chiefof Journal Watch (published by NEJM), Dr Harlan Krumholz, Harold Hines Jr, professor of medicine in the Section of Cardiovascular Medicine at the Yale University School of Medicine (location), said that the study raised important questions about usage of old blood for use in cardiac surgery transfusions.

"With a blood supply in constant demand, finding a solution to this problem will not be easy," he said. He added: "For now, it seems reasonable to try to ensure that patients needing transfusions who are at the highest risk for adverse events receive blood that is as fresh as possible."

Previous, smaller studies have raised questions about the shelf life of donated blood and risks to patients. And some hospitals have developed new procedures to minimize the use of donated blood during cardiac surgery, such as reducing anemia before surgery, using drugs to stop bleeding during and after surgery, increasing the use of "scavanged blood" where blood lost by the patient is saved and reused, and even discharging patients with a lower than normal red cell count, according to a report by the Los Angeles Times.

The paper reports that the Cleveland Clinic researchers are planning to conduct a prospective, blinded, radomized controlled study to confirm the findings.

Magnetically shielded room enables new research on stroke

Researchers from the Physikalisch-Technische Bundesanstalt (PTB; Braunschweig, Germany) have reported that they working on experiments in neurovascular coupling to understand the preliminary events in the brain leading to stroke.

They are researching the temporal correlation between the oxygen requirement of the nerve cells and the oxygen supply through the blood. They says they have succeeded for the first time in vivo with a temporal resolution of 100 ms.

To achieve this the neuronal activity (brain current) was measured simultaneously with the accompanying vascular signal changes (blood volume and oxygenation) during sequences of finger movement.

This combined study is only possible within the magnetically shielded room at PTB (BMSR-2) as this room offers a unique environment for DC-magnetoencephalography, a measure of neuronal activity. The concentration changes of oxygenated and deoxygenated hemoglobin are assessed optically using another advanced technique, time resolved near infrared spectroscopy, which is compatible with DC- magnetoencephalography.

The results show cthat the instantaneous change in neuronal activity is followed by a slower change on the scale of seconds in the blood supply. This temporal relation might be altered in stroke patients with possible new diagnostical insights.

The quantitative characterization of neuro-vascular coupling has another important application: Functional magnetic resonance imaging (fMRI) relies on vascular changes, whereas electro- and magnetoencephalography (EEG, MEG) are direct measures of neuronal activity. The experiments are designed to be able to relate one type of measurement to the other.

Texas physicians exploring mesenchymal 'precursor' stem cells for CHF

Physician scientists at the Texas Heart Institute (THI) at St. Luke's Episcopal Hospital (Houston) have reported beginning what they said is the world's first clinical trial to treat heart attack patients with a type of stem cell to promote better healing and to prevent congestive heart failure, which often develops following heart attack.

The stem cells used in this study, known as mesenchymal precursor stem cells, are allogenic, that is, taken from the bone marrow of a healthy donor and grown in cultures. The cells are injected directly into the heart with a catheter, and the researchers say they appear not to provoke rejection by the recipient or cause inflammation.

The first patient treated was a a 65-year-old man, who, following a heart attack was treated with angioplasty and stenting. The stem cell procedure was done in the cath lab 10 days after the heart attack and he was discharged two days later.

Emerson Perin, MD, PhD, director of the Stem Cell Center of THI and recently appointed director of clinical research for cardiovascular medicine at THI, said that preclinical trials "established that 10 days after the heart attack is the optimal time to give this treatment. The heart is still inflamed in the days just after a heart attack. If we wait too late, the heart will have too much scar tissue and its ability to pump will already be compromised."

The randomized Phase I trial will include 25 patients in three phases in which the patient receives 25, 75 or 150 million stem cells. 3-D imaging is used to map the electrical and mechanical function of the left ventricle, and the stem cells are injected into damaged but still viable areas of the heart muscle.

The study is sponsored by Angioblast Systems (), provider of the cells, a provider of the cells.

"This is a major milestone in the adult stem cell research we began eight years ago. Our challenge remains to identify the very best types of stem cells, refine our delivery techniques, and establish the most effective doses of stem cells. We also have much work to do in understanding the molecular mechanisms by which stem cells differentiate into specific organs and tissue," said James Willerson, MD, president-elect and medical director of THI at St. Luke's and president of The University of Texas Health Science Center at Houston.

Willerson noted that we all have stems cells, "just not in sufficient numbers to perform the healing we need. I believe we were meant to learn of the powerful potential of stem cells and build on it... . . Ultimately, stem cell research could give us the ability to regenerate whole hearts," said Willerson.

Perin and Willerson and their team have developed a network of several hospitals to identify patients who may fit the criteria to be enrolled in this trial."We're already seeing promising results from treating patients with severe heart failure with their own stem cells.... [W]e hope to find a way to help patients before they get so sick," said Perin.