Biomedical subjects

Leonidas Diamantopoulos

Publications and source records attributed to Leonidas Diamantopoulos.

4 recordsLinked to original sources

PubMed2003

The effect of reduced blood-flow on the coronary wall temperature. Are significant lesions suitable for intravascular thermography?

AIMS: The purpose of this study was to investigate the relation between acute coronary flow reduction and arterial wall temperature. METHODS AND RESULTS: Five pigs with normal coronary arteries were catheterized. Arterial wall temperature was studied with a thermographic system that uses a 4-thermistor sensor tip. Flow velocity was studied at the same time and place with the temperature measurements, using a Doppler wire. In order to modify the coronary flow, a balloon was gradually inflated proximally to the thermographic sensors. Temperature differences and flow velocities were simultaneously recorded. Flow velocities above an average peak velocity (APV) of 9 cm/s were associated with unaffected temperature measurements. At flow velocities around 4 cm/s, the wall temperature was increased (deltaT=0.015+/-0.005 degrees C, P approximately 0.05), following the heart-rate. When flow velocity dropped further below this value, the local wall temperature was logarithmically increased to a maximum value observed at total vessel occlusion (deltaT=0.188+/-0.023 degrees C, P<0.001). CONCLUSION: The reduction of coronary flow has an effect on the arterial wall temperature. This effect however, appears only below a critical threshold of APV and in a logarithmic fashion. Above this threshold, temperature measurements should be unaffected from flow reductions and related to the regional temperature heterogeneity.

Animals↗

PubMed2003

Arterial wall thermography.

An atherosclerotic plaque is considered vulnerable when it is at higher risk of inducing acute cardiac events. The early detection and follow-up of the vulnerable plaque are crucial to prevent these events from happening. To date there are no proven techniques to detect such a plaque. Arterial wall thermography, tracing the heat signature of the activated macrophages, is a new and promising method in this direction. However, the difficulties of applying such a method in vivo should not be neglected. Current science proposes several potential thermographic methods. They can be generally categorized as noninvasive and invasive. Magnetic resonance thermometry (MRT) is the most important noninvasive method. It is novel, accurate, and reproducible, but is unfortunately hampered by resolution limitations due to the size and motion of the target vessels. The "infrared" and the "contact-sensor" are the most important invasive thermographic methods. Mainly due to the difficulties of infrared radiation in penetrating the flowing blood, the contact thermographic methods seem to be the most feasible at present. The superiority of thermal mapping of the arterial wall versus the localized temperature measurements is clear. The use of multiple thermal sensors arranged around the vessel's circumference and the application of motorized catheter pullback, not only ensure a large area of coverage, but also enable us to build thermal maps and vascular thermoanatomical reconstructions by using modern computer technology. It is expected that arterial thermography will undoubtedly initiate debate, mainly concerning the most appropriate therapy for the vulnerable plaque. Data collection and correct interpretation are expected to lead us into making wise decisions.

Arteries↗

PubMed2003

Arterial wall temperature following coronary stent implantation in pigs: the role of post-stent inflammation.

BACKGROUND: The purpose of this study was to investigate in vivo the arterial wall temperature after coronary stent implantation in pigs. METHODS: We performed cardiac catheterization in 20 pigs with normal coronary arteries. Arterial wall temperature was studied with a thermography system that uses a 4-thermistor sensor tip. A segment was selected in the proximal right coronary artery. Temperature was mapped in this segment by means of a continuous catheter pullback. A stent was then implanted in the middle of this area, and the temperature scan was repeated. Pigs were randomized in two groups (10 + 10 pigs) for arterial temperature scanning: group A to be re-scanned after 5 days and then sacrificed, and group B to be re-scanned after 8 days and then sacrificed. RESULTS: The temperature of the arterial wall before stent implantation was equal to the adjacent areas. Immediately after stent implantation, the stented area had lower temperature than the adjacent areas (p < 0.001). Five days after implantation, the stented area was significantly warmer than the adjacent areas (p < 0.001); histopathology showed the highest macrophage population at the place of the stent. Eight days after implantation, the temperature differences were reduced to non-significant levels (p = NS) and the macrophage population was significantly lower. CONCLUSION: Stent implantation results in an immediate temperature decrease at the stented arterial segment, followed by a significant temperature increase around day 5 after stent implantation. These findings can be correlated with the peri-strut inflammation that follows the stent implantation.

Animals↗

PubMed2002

Imaging of atherosclerosis. Intravascular imaging of the vulnerable atherosclerotic plaque: spotlight on temperature measurement.

The vulnerable atherosclerotic plaque is associated with an increased number of acute coronary syndromes. Current techniques such as coronary angiography are unable to detect and prospectively evaluate these lesions. Recently, other techniques, both invasive and noninvasive, are being developed trying to detect the plaque that is at increased risk for rupture eventually resulting in increased thrombosis. This review describes briefly evolving techniques for imaging of vulnerable plaques and describes in detail intravascular thermography.

Animals↗