Several studies have identified the degree of aortic valve calcification as a strong predictor both for the progression and
outcome of aortic stenosis. In industrialized countries, aortic valve stenosis is most frequently caused by progressive
calcification and degeneration of aortic cusps. However, there are no accurate methods to quantify the extent of aortic
valve calcification. To provide a non-invasive alternative to biopsy, a range of optical methods have been investigated,
including Raman and reflectance spectroscopy. A Raman spectrum can be used to access the molecular constitution of a
particular tissue and classify it. Raman spectroscopy is largely used in the quantification and evaluation of human
atherosclerosis, being a powerful technique for performing biochemical analysis without tissue removal. Nevertheless,
increased thickness and disorganization of the collagen fibre network and extracellular matrix are known to affect the
diffuse spectral reflectance of the tissue. A catheter with the "6 around 1" configuration, the central fiber transmit laser
radiation to the sample and the scattered light is collected by the other six surrounding fibers, was used both for Raman
and reflectance spectroscopy. A white light (krypton lamp, flashtube Model FX 1160 Perkin Elmer, USA) excitation was
used for reflectance measurements. A Ti-sapphire (785nm, Spectra Physics, model 3900S, USA) laser, pumped by an
argon laser (Spectra Physics, model Stabilite 2017, USA) was used as the near infrared Raman set up. Several ex-vivo
spectra of aortic valve samples were analyzed. The results show a promising way to differentiate normal, fibrous and
calcified tissue in aortic valve.
Comparative studies were carried out on the Al- phthalocyanine and Zn-phthalocyanine uptake in iliac artery wall of rabbit, through transadventitial fluorescence measurements. Two 3.5 Kg Norfolk make rabbit were used. The iliac artery was dissected, isolated and clamped at two points, 1.5 cm apart. The experiment comprised three steps, collecting fluorescence spectra at several point inside and outside of the clamped region of the artery. The excitation source was a 488 nm Argon Laser. Firstly, it was measured the pre and post clamping transadventitial fluorescence without the photosensitizer. After that, 50 (mu) L of AlPc or ZnPc solutions in Cremiphor EL, 2.5 (mu) M, were injected locally into the artery clamped region of each rabbit and fluorescence spectra were collected at t equals 0 and 15 min. Finally, elapsed 30 min. Temporal evolution of the drug uptake by the artery wall was studied analyzing the intensities of the fluorescence peaks at 682 and 678 nm for AlPc and ZnPc, respectively. It was found that AlPc is more absorbed and remains for a longer time in the iliac artery wall than the ZnPc.
A growing number of studies have demonstrated that autofluorescence and induced fluorescence spectroscopy can be used to distinguish normal and abnormal tissues in vivo. Through photochemical accumulation in atherosclerotic lesions it is possible to obtain induced fluorescence, this accumulation has been demonstrated in many researches. The aim of this study was to diagnose, by aluminum phthalocyanine transadventitial fluorescence, atherosclerotic plaques in artery wall of rabbits. Five male Norfolk rabbits were submitted to a high level cholesterol diet for 9 weeks. When the blood cholesterol level reached around 1000 mg/dl three of these animals were injected intravenously 50(M/50(l of aluminum phthalocyanine (AlPc). After 24 hours these animals were submitted to a surgery to expose the iliac artery. The transadventitial fluorescence spectra were acquired in several points over the artery. Characteristic peaks of the collagen, the porphyrin and the induced by AlPc were observed.
The aim of this work was to verify the Al-Phthalocyanine (AlPc) absorption in iliac artery wall of a rabbit, through transadventitial fluorescence measurement. Two Norfolk male rabbits, weighing 3.5 kg were used. The iliac artery was dissected and isolated. The artery was then clamped in two points with simple ligatures spaced 1.5 cm. The experiment was made in three phases, with acquisition of several fluorescence spectra in different points of the iliac artery. Firstly was measured the pre and post clamping transadventitial fluorescence without the presence of the photosensitizer. On the second phase, the AlPc, 2.5 (mu) M in 50 (mu) L solution, was injected locally into the clamped region and fluorescence spectra were collected in t=0 minutes and t=15 minutes. Finally, 30 minutes from the beginning of the experiment the clamping was removed, the blood flow restarted into the artery, and the fluorescence spectra was collected in t=5 minutes and t=10 minutes. The excitation was made using an Argon Laser (Stabilite 2017-Spectra Physics), operating in 488nm with 7mW optical power measured at the distal fiber tip. A unique peak, centered in 682nm, identifies the AlPc presence on the analyzed tissue.