A pilot clinical study has shown that a new noninvasive technique is equally as effective at measuring arterial wall thickness, noncalcified plaque and degree of stenosis as traditional methods.
The method involves using a voxel analysis technique in combination with multidetector computed tomography angiography (MDCTA) to quantify the volume of noncalcified plaque within a blood vessel.
“The importance of quantifying plaque is critical because total plaque burden is considered the most important predictor of coronary events,” explains the study’s senior author Melvin Clouse. “Furthermore, the rupture of soft noncalcified plaque has been implicated as the cause of heart attack.”
Standard techniques used to diagnose atherosclerosis include exercise stress testing and coronary angiography, but both of these methods work by visualizing the lumen, which also increases in size as plaque progresses.
“Because soft plaque buildup may not significantly narrow the lumen, conventional angiography and stress tests fail to provide a complete picture of plaque accumulation,” continued Clouse.
MDCTA is a noninvasive CT scanning method that provides a detailed cross-sectional view of the blood vessel wall based on the amount and volume of blockage present. They also used voxel analysis; within the selected volume, the number of voxels having a density within the range of plaque is established, from which the volume of plaque is then estimated.
The researchers analyzed 41 normal and eight abnormal arterial cross sections with noncalcified plaque selected from ten patients undergoing MDCTA for percentage of stenosis and plaque volume using a voxel analysis technique.
“By plotting a voxel histogram across the arterial wall, we were able to measure the amount of plaque, as well as the narrowing of the artery,” explains Clouse.
“Using this new method, we hope to be able to be able to better assess the effects of medication treatment and lifestyle interventions in treating atherosclerosis,” he concluded.
The study has shown the technique to be accurate and highlights its potential value in future investigations.
Sources: www.bidmc.harvard.edu Clouse ME, Sabir A, Yam C-S et al. Measuring noncalcified coronary atherosclerotic plaque using voxel analysis with MDCT angiography: a pilot clinical study. Am. J. Roentgenol. 190, 1553–1560 (2008).
Taser shock restores a man’s heart rhythm to normal
A recent case study has reported on a patient receiving a shock from a neuromuscular incapacitating device leading to a positive clinical outcome.
A 28-year-old man with a medical history of depression, anxiety and bipolar disorder presented to the emergency department after fleeing from the police, hiding in a lake for approximately 40 min and then eventually being detained.
Owing to concerns of hypothermia, the patient was brought to the emergency department and was found to have a rapid and irregular pulse rate of up to 145 bpm and observed to be in atrial fibrillation. The patient became agitated, began ripping off his monitoring electrodes and attempted to pull out his intravenous line. Security helped to control the patient and he became threatening to the hospital staff and the police officer who accompanied him. The patient received a shock from the Taser, delivered by the police officer. His pulse was immediately checked and he was found to have a rapid but regular rhythm. An ECG was performed immediately showing sinus tachycardia and a pulse rate of 120 bpm.
“This is the first report of a patient receiving a shock of this kind and having a positive outcome,” said the study author, Dr Kyle A Richards, “In this instance, the patient received a very low dose of electrical current, but it was still enough to restore him to regular heart rhythm. ”
Many have reported on the potentially harmful effects of neuromuscular incapacitating devices. While this report does not prove that the Taser was responsible for the cardioversion, it emphasizes the need for further research.
Sources: www.acep.org/pressroom.aspx?id=25188, Richards KA, Kleuser LP, Kluger J. Fortuitous therapeutic effect of taser shock for a patient in atrial fibrillation. Ann. Emerg. Med. PMID: 18514367 (2008) (Epub ahead of print).
Flavanol-containing cocoa reverses vascular dysfunction in diabetes
A new study in which diabetic patients drank specially formulated high-flavanol cocoa has shown a significant improvement in their blood vessel function, from severely impaired to normal.
Flavanols are naturally occurring compounds with antioxidant properties that are found in cocoa, tea, red wine, and some fruit and vegetables. The aim of the study was to test the feasibility and efficacy of dietary intervention of a daily intake of flavanol-containing cocoa to improve the vascular function of medicated diabetic patients. Even in fully medicated diabetic patients, the overall prognosis is unfavorable due to deteriorated cardiovascular function but, based on epidemiological data, it is known that diets rich in flavanols are associated with a reduced cardiovascular risk.
“Medical treatments alone often do not prevent complications of diabetes that are associated with atherosclerosis and cardiovascular disease,” said Malte Kelm, a Professor and Chairman of Cardiology, Pulmonology and Vascular Medicine (University Hospital Aachen and the Technical University Aachen, Aachen, Germany). “Physicians should be increasingly looking to lifestyle changes and new approaches to help in addressing the cardiovascular risks associated with diabetes.”
Dr Kelm and colleagues first tested the feasibility of using high-flavanol cocoa to improve cardiovascular function in ten patients with Type 2 diabetes; they observed the effects and tolerability of acute single-dose ingestions of cocoa with increasing concentrations of flavanols on vascular function. The team then investigated the effectiveness of long-term (30-day), thrice-daily dietary intervention with either high-flavanol cocoa (321 mg flavanols per dose) or nutrient-matched, low-flavanol cocoa (25 mg per dose) as a control in 41 patients with Type 2 diabetes. The study was randomized and performed in a double-blind fashion so that neither the patients nor the investigators knew which type of cocoa each patient had been assigned to drink. Blood vessel function was assessed on day 1 before cocoa consumption and then 2 h afterwards; this was repeated on day 8 and day 30.
Vascular function was measured using flow-mediated dilation (FMD), which assesses the ability of the arteries to dilate in response to an increase in demand for blood, oxygen and nutrients. The FMD test involves measuring the diameter of the brachial artery in the upper arm using ultrasound, then inflating a blood pressure cuff on the forearm for several minutes. The squeezing of the cuff temporarily starves the forearm muscles of blood and oxygen, causing the body to increase blood flow to those muscles. In healthy people, the increased blood flow is detected and the arteries expand. In Kelm’s laboratory, the average normal FMD response among healthy people the same age as those participating in the study is a 5.2% expansion in arterial diameter.
This study found that patients with Type 2 diabetes had a severely impaired FMD response at the beginning of the study; before cocoa consumption the brachial artery expanded by only 3.3%, on average. At 2 h after drinking the high-flavanol cocoa, the FMD response had risen to 4.8%.
After patients drank high-flavanol cocoa three-times daily for 8 days, the average FMD response improved to 4.1% at baseline and 5.7% 2 h after cocoa ingestion. By day 30, the FMD response had improved to 4.3% at baseline and 5.8% after cocoa ingestion. All of the improvements were highly statistically significant. The improvement was as large as has been observed with exercise and many common diabetic medications, the researchers noted.
Among patients who consumed the low-flavanol cocoa, there were no significant differences in baseline FMD response over time, or in FMD response after cocoa ingestion on days 8 and 30.
Kelm speculated that cocoa flavanols improve FMD response by increasing the production of nitric oxide, the chemical signal that tells arteries to relax and widen in response to increased blood flow. Relaxation of the arteries takes stress off of the heart and blood vessels.
The high-flavanol cocoa used in this study had a much higher concentration of flavanols than the typical dietary intake of 20 to 100 mg daily, and is not sold in the supermarket. Kelm cautioned that the take-home message of the study is not that people with diabetes should consume lots of cocoa, but rather, that dietary flavanols hold promise as a way to prevent heart disease.
Sources: www.acc.org Balzer J, Rassaf T, Kelm M et al. Sustained benefits in vascular function through flavanol-containing cocoa in medicated diabetic patients: a double-masked, randomized, controlled trial. J. Am. Coll. Cardiol. 51, 2141–2149 (2008).
Study shows that long-term cognitive decline in bypass patients is not due to surgery
There have been concerns, due to some studies, that coronary artery bypass grafting should not be chosen as an intervention for coronary artery disease due to its implication in postoperative cognitive decline. A new study, led by Ola A Selnes and Guy M McKhann of the Johns Hopkins University School of Medicine, has found that there is no evidence that patients who have undergone coronary bypass surgery have a greater risk of long-term cognitive decline.
The study involved 152 patients with coronary artery disease who had bypass surgery and 92 patients with coronary artery disease without surgical intervention. Patients underwent a series of memory and other cognitive tests at the beginning of the study period and after 3, 12, 36 and 72 months. The results showed that there were no significant differences in cognitive scores between the two groups at the beginning of the study. Both groups showed modest decline in cognitive performance during the study period, but there were no significant differences in the degree of decline between the groups after 6 years.
While studies have been done previously to investigate cognitive decline after coronary bypass surgery, these studies had been performed without appropriate control subjects; this is the first prospective long-term study comparing cognitive outcomes of bypass patients to cardiac patients who did not have surgery.
The authors note that it is likely that the cognitive decline is related either to normal aging in the context of cardiovascular disease or to progression of the underlying vascular disease over time. More studies are needed, however, to determine if better control of risk factors, such as risk factors for vascular disease and markers of atherosclerosis, would lessen the degree of cognitive decline in patients with coronary artery disease. They also note that the study emphasizes the importance of including control subjects when studying long-term cognitive outcomes after surgical procedures. From this study, it can be concluded that the risk of late cognitive decline should not be a consideration when choosing between types of intervention for cor-onary artery disease.
Sources: www.blackwellpublishing.com/press/default.asp Selnes OA, Grega MA, Bailey MM et al. Cognition 6 years after surgical or medical therapy for coronary artery disease. Ann. Neurol. 63, 581–590 (2008).