Fluorescence spectroscopy guidance of laser ablation of atherosclerotic plague

Laser-induced fluorescence (LIF) spectroscopy can only be used for laser angioplasty guidance if high-power laser ablation does not significantly alter the pattern of tissue fluorescence. Although the spectra of normal and atherosclerotic arteries differ, the change in fluorescence spectra following laser angioplasty has not been well studied. Therefore, the purpose of this study was to assess whether laser-induced fluorescence spectroscopy could guide selective laser ablation of atherosclerotic plaque and, if so, to develop a quantitative LIF score that could be used to control a "smart" laser angioplasty system. Baseline LIF spectroscopy of 50 normal and 50 atherosclerotic human aortic specimens was performed using an optical fiber coupled to a He-Cd laser and optical multichannel analyzer. LIF was then serially recorded during erbium:YAG laser ablation of 27 atherosclerotic specimens. Laser ablation was terminated when the arterial LIF spectrum visually appeared normal. Histologic analysis revealed a mean initial plaque thickness of 1,228 +/- 54 microns and mean residual plaque thickness of 198 +/- 27 microns. Ablation of the media occurred in only three specimens. A discriminant function was derived to discriminate atherosclerotic from normal tissue for computer guidance of laser angioplasty. The LIF score, derived from stepwise multivariate linear regression analysis of the LIF spectra, correctly classified 93% of aortic specimens. The spectra obtained from the atherosclerotic specimens subjected to fluorescence-guided laser revealed a change in score from "atherosclerotic" to "normal" following plaque ablation. Seven atherosclerotic specimens were subjected to laser angioplasty with on-line computer control using the LIF score. Mean initial plaque thickness was 1,014 +/- 86 microns, and mean residual plaque thickness was 78 +/- 29 microns. There was no evidence of ablation of the media. Therefore, LIF guidance of laser ablation resulted in minimal residual plaque without arterial perforation. These findings support the feasibility of an LIF-guided laser angioplasty system for selective atherosclerotic plaque ablation.     

Anaesthetic experience with paediatric interventional cardiology

Anaesthetic and sedation techniques, complications and outcomes were reviewed in 176 children undergoing 184 interventional cardiologic procedures. Techniques included sedation only, and ketamine, inhalational or narcotic anaesthesia. Ketamine infusion was the technique most frequently used. Ketamine was associated with a higher incidence of respiratory complications (P < 0.05) than the other techniques. The higher incidence of hypercarbia (15.6 per cent), which did not affect outcome, may be attributable to the use of supplemental sedatives. The incidence of upper airway obstruction (7.8 per cent) was similar to that of previous studies. Vascular compromise resulted from the procedure in 33 patients, necessitating surgical correction in 16. Cardiac perforation occurred in four cases, causing one death. Pulmonary valve stenosis was most amenable to balloon dilatation and aortic valve stenosis least amenable. Ketamine was the anaesthetic agent preferred by cardiologists for use in the catheterisation suite when general anaesthesia was required. Vigilant monitoring by anaesthetic staff is necessary during the procedure, and avoidance of concomitant narcotics is recommended if a ketamine technique with spontaneous ventilation is used. Les techniques anesthésiques et de sédation ainsi que les complications et les issues ont été revues chez 176 enfants subissant 184 procedures cardiaques. Les techniques ont inctu soil la sédation seulement, soit l’anesthésie à la kétamine, aux agents d’inhalation ou aux narcotiques. La perfusion de kétamine était la technique la plus fréquemment utilisée. La ketamine était associée à une plus grande incidence de complication respiratoire (P < 0.05) comparativement aux autres techniques. La plus grande incidence d’hypercarbie (15.6 pour cent), n’ayant pas affecté l’issue, pourrait être attribuée à l’utilisation additionnelle de sédatifs. L’incidence d’obstruction des voies aériennes supérieures (7.8 pour cent) était similaire aux études préalables. Un problème vasculaire suite à la procédure fut observé chez 33 patients dont 16 ont requis une correction chirurgicale. Une perforation cardiaque est survenue dans quatre cas provoquant le décès d’un seul patient. La sténose de la valve pulmonaire était la procédure la plus susceptible d’être dilatée et la sténose de la valve aortique la moins susceptible. La kétamine était l’agent anesthésique préféré par les cardiologistes lors des cathétérisations quand une anesthésie générate était requise. Une surveillance vigilante par une équipe anesthésique fut nécessaire durant la procedure. Il faut aussi éviter l’administration de narcotiques si la kétamine est administrée en respiration spontanée.

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Presented in part at the Canadian Anaesthetists’ Society annual meeting in Halifax, June 1988.     

Character and frequency of pathological changes in the solitary rat kidney after removal of the other kidney in old age

One kidney was removed from male rats weighing 500–850 g; the remaining kidney underwent compensatory hypertrophy and, after 1–2 months, it was larger (index of hypertrophy 70–92%) in rats weighing 700–850 g than in animals weighing 500–600 g (56–58%). Histological investigation showed that this marked hypertrophy of the solitary kidney in old rats was not the result of disease of the organ, for pathological changes such as are sometimes found in intact and hypertrophied kidneys were found in only 38 of 223 animals. The results suggest that the ability of the kidneys to undergo, compensation and regeneration is not reduced in old age.Laboratory of Growth and Development, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 9, pp. 362–366, September, 1977.     

强力霉素影响基质金属蛋白酶活性和血管重构的实验研究

目的：观察强力霉素对损伤动脉组织中基质金属蛋白酶（MMP）活性的抑制作用，并探讨强力霉素对血管平滑肌细胞增殖、动脉内膜增生、管腔重构的影响。方法:球囊导管扩张动脉的方法建立大鼠颈总动脉损伤模型。治疗组用强力霉素30 mg·kg^-1·d^-1干预。明胶酶谱法测定损伤动脉组织中MMPs的活性。用HE染色、VVG染色、免疫组化标记α-actin和增殖细胞核抗原的方法观察损伤动脉内膜厚度、管腔重构及平滑肌细胞增殖的情况。结果:①强力霉素治疗组MMP-9活性在术后24 h、3 d分别比对照组低26.3％、34.5％（P<0.01）；MMP-2活性在术后7 d比对照组低40.0％（P<0.01）。②强力霉素治疗使术后7 d内膜平滑肌细胞增殖率（43.23％±1.06％）显著低于对照组（62.76％±1.02％）（P<0.01）；使术后14 d、28 d新生内膜厚度比对照组分别少32.0％、38.8％（P<0.01），而管腔面积比对照组多58.0％、90.4％（P<0.01） 。结论：强力霉素可以显著降低血管损伤后MMPs活性，抑制内膜平滑肌细胞的增殖、新生内膜增生以及管腔重构，提示它可能具有防治PTCA术后再狭窄的作用。     

经皮血管腔内成形术在布-加综合征中的应用

我们自1991年11月～1996年12月为32例布-加综合征患进行经皮血管腔内成形术治疗，其中膜型阻塞或狭窄21例，采用大球囊一次性扩张；段型11例，采用内支架植入术。其中28例随访2～60个月，疗效满意；管腔通畅，无严重并发症，无死亡。我们认为该技术安全，简单，对布-加氏综合征治疗有效，尤适合于肝段下腔静脉膜型阻塞的患。     

Influence of vascular parameters on the effectiveness of intra-aortic balloon pumping: A model study

The intra-aortic balloon pump has been widely used as a temporary heart-assist device. In this investigation, a nonlinear mathematical model of the arterial system and intra-aortic balloon pump was studied analytically. Thus, the influences of a number of vascular parameters on the effectiveness of intra-aortic balloon pumping (IABP) were determined. The effects of changes in vascular parameters of the model on a number of performance indexes were investigated. These performance indexes (aortic mean diastolic pressure, aortic end diastolic pressure, cardiac output, coronary flow and phase differences between the fundamental Fourier components of aortic root pressure and flow) were used as the criterion for an evaluation of the effectiveness of the assist pump. The following vascular parameters were perturbed by four steps (±10%, ±20%) from the values in the standard model: heart rate, peripheral resistance, left ventricular pressure, aortic elastance, aortic radius, arterial wall thickness, and aortic length. This model was evaluated for a wide range of balloon-pump phase-control settings (assisted case) and for the unassisted case (when the pump is disabled). It is concluded that changes in heart rate, peripheral resistance and left ventricular pressure cause the most significant changes in pump performance. Dr. Ohley is with the Datascope Corporation Dr. Kao is with the Technicare Corporation     

The mechanisms of coronary restenosis: insights from experimental models

Since its introduction into clinical practice, more than 20 years ago, percutaneous transluminal coronary angioplasty (PTCA) has proven to be an effective, minimally invasive alternative to coronary artery bypass grafting (CABG). During this time there have been great improvements in the design of balloon catheters, operative procedures and adjuvant drug therapy, and this has resulted in low rates of primary failure and short-term complications. However, the potential benefits of angioplasty are diminished by the high rate of recurrent disease. Up to 40% of patients undergoing angioplasty develop clinically significant restenosis within a year of the procedure. Although the deployment of endovascular stents at the time of angioplasty improves the short-term outcome, 'in-stent' stenosis remains an enduring problem. In order to gain an insight into the mechanisms of restenosis, several experimental models of angioplasty have been developed. These have been used together with the tools provided by recent advances in molecular biology and catheter design to investigate restenosis in detail. It is now possible to deliver highly specific molecular antagonists, such as antisense gene sequences, to the site of injury. The knowledge provided by these studies may ultimately lead to novel forms of intervention. The present review is a synopsis of our current understanding of the pathological mechanisms of restenosis.     

Reduction of latex-allergen content in Swedish medical catheter balloons – a survey of 3 years' production

Anaphylactic reactions after intravascular exposure to natural rubber latex (NRL) have been reported. Thus, there is an urgent need to produce medical devices with the lowest possible latex-allergen content. The latex-allergen concentration in extracts prepared from 92 lots of medical catheter (MC) balloons, manufactured by Nolato Polymer AB, Torekov, Sweden, from April 1993 to March 1996, was measured with an EAI (IgE antibody inhibition) assay. Inhibitory capacity was expressed in arbitrary units/ml (U/ml) in relation to reference NRL sap, given an arbitrary value of 1000 U. Extracts from randomly selected lots were measured for protein by the modified Lowry method. Water leaching, chlorination, and treatment with savinase were used experimentally to study reduction of the latex-allergen content. The latex-allergen content in extract from the regular MC balloons varied from 0.1 to 2.9 U/ml. All the methods used to reduce the allergen content were effective, and increased leaching stabilized the allergen content at a low level. The protein concentration of the extracts varied between 9 and 100 mg/1. No correlation was found between protein and allergen content. As a result of this study, the manufacturer has extended the stage of water leaching in the production process. This study shows that cooperation between immunologists and manufacturers may result in product development and improvement.     

冠脉内支架临床发展策略

冠脉内支架是临床上预防ＰＴＣＡ并发症的有效措施，但金属支架固有的血栓菜成原性和对血管壁组织的永久性刺激可导致院内心脏事件和再狭窄。为解决上述问题，作者提出，血管内支架联合靶向药物传输离子照射或基因治疗、基因修饰的内皮细胞的种植支架、吱物可吸收缓释药物支架材料研制为临床冠脉内支架开辟了广阔的发展前景。