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Biomedical subjects

H Geschwind

Publications and source records attributed to H Geschwind.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Results of pulsed laser angioplasty of peripheral arteries guided by spectroscopy].

Seventy-six patients with complete occlusion of the iliac, femoropopliteal or distal arteries underwent laser angioplasty after failure of attempted mechanical recanalization by conventional angioplasty. The energy source was a dye pulsed laser emitting at 480 nm, 2 microseconds, 35 to 50 mJ/pulse and 5 Hz. The laser was coupled with an optical fiber of 200 microns diameter covered by a metallic spring. In order to center the laser in the arterial lumen, the fibre optic was introduced with a balloon catheter or a modified Van Andel catheter with a tapered and curved distal end with controlled torsion to direct the laser towards the lesion to be treated. The therapeutic laser was connected to a diagnostic Helium-Cadmium laser emitting at 325 nm, 50 ms and 5 mW, for the induction of tissue fluorescence analysed by a multichannel detector, itself connected to a computer programmed to differentiate atheromatous from normal tissues. The therapeutic laser was only activated when atheromatous tissue was in contact with the distal tip of the fiber optic. After vaporizing a narrow pilot channel conventional balloon angioplasty was performed. The immediate success rate was 83%; it was higher in iliac than in femoral arteries. This was less dependent on the length of occlusion than on the presence of calcification which was a common cause of failure. The complications were immediate reocclusion, perforation due to the sharp tip of the fibre and dissections without major clinical consequences. After 18 months, 64% of the arteries remained patent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Laser and arterial recanalization].

Interventional cardiorhythmology was born with the invention of electrical catheter ablation of the common atrioventricular bundle of His as a palliative treatment of supraventricular arrhythmias refractory to medicinal treatment. This method is now used as a curative treatment. In Wolff-Parkinson-White syndrome, all accessory pathways, whatever their location, can be destroyed with a very high success rate (96 p. 100) and very low morbidity and mortality rates. Reentrant nodal tachycardias can also be treated by catheter ablation with, however, a low risk of atrioventricular block which, for the moment, limits its indications. In intractable ventricular tachycardias, its indications will certainly be extended and its efficacy will increase since numerous recent studies have identified a limited, slow-conduction area (arrhythmogenic substrate) as being the real target for ablation. Other sources of energy are also used for the same purposes, including radiofrequency currents with results that are promising but vary according to the type of arrhythmia treated. Thus, interventional cardiorhythmology is progressively replacing surgery.

Angioplasty, Laser↗
PubMed1990

Prophylactic intraventricular pumping in high-risk coronary angioplasty.

The 'Hemopump', an axial flow pump, when inserted in the left ventricle brings about mechanical unloading of the ventricle, thus reducing the risk of cardiac arrest during coronary angioplasty. In this study eight very ill patients with unstable myocardial ischaemia and various contraindications for coronary artery surgery were selected for coronary angioplasty with insertion of the hemopump. Anatomical difficulties prevented insertion in three patients, but coronary angioplasty was carried out successfully with the pump in place in the other five. When the pump was working the cardiac index rose by an average of 23% (8-50%) and the pulmonary capillary wedge pressure fell by 17% (0-22%). Though electrocardiographic monitoring showed temporary rhythm instability during angioplasty in four of the five patients, there was no clinical deterioration. Four of the five patients are symptom-free on medical treatment and the other is well after surgical revascularisation.

Aged↗
PubMed1990

[The intracardial hemopump. A new technique of left ventricle assist device].

A new left ventricular assist device consisting of a canula containing a turbine introduced by retrograde catheterisation was evaluated in the prevention of complications in 9 patients undergoing high risk coronary angioplasty. The good clinical and hemodynamic status during and after coronary dilatation confirmed the system's innocuity and its efficacy each time it could be correctly positioned in the ventricle (6 patients). These extremely encouraging preliminary results suggest that an additional simplification but reducing the size of the canula and increasing turbine flow, allowing percutaneously introduction would constitute a significant development.

Aged↗
PubMed1989

[Early angioplasty in unstable angina. Results apropos of 60 consecutive patients].

Transluminal coronary angioplasty (TCA) is an attractive means of suppressing ischaemia in patients (pts) with unstable angina. Sixty consecutive pts underwent TCA 6 +/- 2.5 days on average after their admission. Only the ischaemic vessel was dilated (mean stenosis 79 p. 100). Primary success was obtained in 53 pts (88 p. 100) with 31 p. 100 of residual stenosis after TCA. Two pts underwent emergency surgery for extensive dissection; failure of traversing the stenotic segment occurred in 2 pts; 3 pts had myocardial infarction (MI) less than 1 h after TCA, 2 arteries have been recanalized by intracoronary streptokinase with persistence of a satisfactory result of TCA, the 3rd patient had occlusion of a secondary side branch. During their stay in hospital, 2 pts had coronary bypass for recurrent angina. After a follow-up period of 6 to 16 months (mean 10 months) early recurrence of angina was observed in a number of cases (before the sixth month in 7 pts). One pt developed MI during the fourth month. At six month, 10 or the initial 60 pts had undergone coronary bypass, 1 undilated pt was asymptomatic; out of 49 dilated pts (47 with one single TCA), 39 were symptom-free but 6 had a positive exercise test, 7 pts were in class II and one in class IV. At control coronary arteriography (46 pts) restenosis was present in 39 p. 100: 5 new TCA and 2 aorto-coronary bypasses were performed. At one year 28 pts had been followed up: 1 was in class IV and 1 in class II, the others being asymptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[6 months' results of coronary angioplasty after thrombolysis of myocardial infarction].

Transluminal coronary angioplasty (TCA) has become the treatment of choice of residual stenosis after thrombolysis for myocardial infarction, but the long-term results of TCA are imperfectly evaluated. Seventy patients underwent TCA after thrombolysis on account of a significant (greater than 50 p. 100) residual stenosis of the artery responsible for the infarction. TCA was performed less than 6 hours after the onset of symptoms in 15 patients who had neither clinical nor electrocardiographic evidence of reperfusion; 4 of these patients were in a state of cardiogenic shock. In the remaining patients TCA was performed 1 to 10 days (mean 3.2 days) after thrombolysis. A primary success was obtained in 64 patients (91 p. 100). Two patients had emergency aorto-coronary bypass. During their stay in hospital, 5 patients presented with symptoms of reocclusion which in 4 of them occurred less than 24 hours after TAC, and 2 of these 4 patients had to be reoperated upon; 2 patients died suddenly. During a 6 to 18 months' follow-up period (mean 10.5 months), the infarction recurred in 3 patients; the recurrence took place during the 3rd month in 2 of them (1 had another thrombolysis and later TAC) and during the 6th month in the third one. At 6 months, 4 patients were suffering from exertion angina and 2 asymptomatic patients had a positive exercise test. Fifty-two control coronary arteriographies were performed at 6 months. Thirteen patients (25 p. 100) had an occluded artery which was clinically silent in 11; 39 patients had a patent artery with restenosis in 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Percutaneous angioplasty using spectroscopy-guided pulsed laser].

Percutaneous laser angioplasty was performed in 19 patients with calcified and non-calcified occlusions (4-25 cm long) of the superficial femoral artery, using a pulsed dye laser at 480 nm and a pulse duration of 2 microseconds per pulse. The treatment laser was guided by a 325 nm diagnostic laser that induced tissue fluorescence. The laser system operated through a single 200 microns optical fiber. Computer spectral analysis of the tissue fluorescence located at the distal end of the fiber tip directed emission of the treatment laser only at the atheroma without affecting the arterial wall. A successful primary laser recanalization was obtained in all cases and was followed by balloon dilation in all but one patient. One mechanical perforation and 2 mechanical arterial dissections by the fiber, and 1 perforation and 1 dissection by the guide wire occurred, but no complications due to the treatment or diagnostic laser were observed. The safety of the procedure seemed to be enhanced by the spectroscopic guidance system which enabled plaque recognition. The pulsed dye treatment laser was well tolerated and effective even in heavily calcified arteries.

Adult↗
PubMed1989

[Laser angioplasty].

Laser energy is capable of breaking up plaques of atheroma to clear obstructed arteries. Laser rays are transmitted by optic fibers, fine and flexible, or bundles of fibers. In order to avoid perforation of the arterial wall, major difficulty and pitfall of this technique, a centering balloon is used or an absorption gradient between plaque and normal tissue, or improved guiding devices such as angioscopy, ultrasounds or detection of the atheroma by spectroscopy. The laser energy may also be transformed into heat, procedure carried out by thermoplasty. In order to avoid the drawbacks of the cutting end of the bare optic fibers, it may be covered with sapphire optics which conducts well laser energy. Arterial and coronary disobstructions were performed by so called continuous lasers, such as Argon, YAG of pulsed laser such as Excimer or color lasers. These are selectively absorbed by the atheroma and operate according to a computerized system after detection of atheromatous plaques by spectroscopy. Excellent results have recently been obtained with such a system on short and long term complete peripheral arterial obstructions.

Arterial Occlusive Diseases↗
PubMed1989

[Myocardial protection by coronary autotransfusion during angioplasty].

Coronary autologous blood perfusion may protect the myocardium against ischemia during arterial occlusion due to balloon inflation. During balloon inflation, arterial blood was perfused via the balloon catheter in 19 patients with single proximal severe left anterior descending artery stenosis and normal left ventricular function. Blood was perfused using a contrast medium injector at a flow rate of 40 ml/min. The balloon was maintained inflated for 60 seconds at 6 atmospheres. Two inflations were performed with perfusion and 2 without. Myocardial ischemia was assessed by ST elevations on both the peripheral and intracoronary ECGs, changes in left ventricular systolic and end diastolic pressures and peak positive and negative dP/dt. A positive response was obtained in 11 patients. In 5 patients, the myocardial ischemia induced by dilatation was not alleviated by the perfusion and in 3 patients ischemia was increased by perfusion. In conclusion, ischemia is inconsistently reduced by autologous blood perfusion and its adverse effect in some patients could limit its use.

Aged↗
PubMed1986

Histopathology after Nd-YAG laser percutaneous transluminal angioplasty of peripheral arteries.

Laser recanalization of occluded femoral or popliteal arteries was performed in 12 patients using a continuous wave neodymium yttrium aluminum garnet (Nd-YAG) laser. The histologic findings of the laser-irradiated arterial segments in two of these patients are reported. The specimens were obtained 2 and 4 weeks after the laser procedure. The laser-irradiated vessel in Patient 1 had been partially recanalized with reduction of the atherosclerotic occlusion from 3 to 1 cm. The lased arterial lumen manifested thermal injury to the inner quarter of the arterial wall with vacuolization and a rim of carbonization occupying 10% of the width of the arterial wall, but without thrombus formation. Histologic examination in Patient 2 revealed no fibrin deposits, atherosclerotic debris or thrombi at the intimal arterial edge. At the crater site, thermal injury was apparent with vacuolization of the intimal fibrous tissue. The histologic sections obtained 4 weeks after the procedure revealed new fibrous intimal tissue without endothelialization in some of the heavily calcified tissue sections. Where the plaques were noncalcified, reendothelialization was noted with only minimal damage to the surrounding tissue. No medial or elastic fiber disruption was seen, and no aneurysmal dilation had occurred. Intimal splitting with a cleft between the tunica media and the intima was noted at the site of previous balloon angioplasty. In conclusion, the follow-up histologic findings 2 and 4 weeks after laser angioplasty in two patients using a specially designed catheter delivery system and cooling blood perfusate revealed thermal injury to the inner quarter of the arterial vessel wall and no evidence of thrombus formation.

Aged↗
PubMed1986

[Arterial recanalization using the laser. A technic for the future?].

On the basis of two years' experience, a technique for the use of percutaneous endoluminal continuous emission Nd-YAG laser has been developed for arterial recanalisation. The effectiveness of this type of laser has been demonstrated in a large number of clots and atheromatous plaques, including calcified plaques. A balloon catheter gives a coaxial position of the fiber in center of the artery. Infusion of a blood solution containing 3 g of haemoglobin/100 ml at a rate of 20 ml/minute limits the thermal parietal lesions, improves the conditions of laser treatment and eliminates any risk of arterial perforation. No embolic debris is collected down-stream. Recanalisation of long arterial segments in amputated legs was performed prior to the human application. Ten patients have been treated with no mortality and virtually no morbidity. The narrowness of the reformed arterial lumina resulted in early re-thrombosis in the first 5 cases, requiring balloon modelling to ensure patency with a follow-up of 1 to 3 months in the 5 following patients.

Aged↗
PubMed1985

[Arterial disobliteration by the laser].

In order to determine the optimal conditions for disobliteration of occluded arteries without damaging the arterial wall, the effects of a Nd-YAG laser connected to a 0.2 mm diameter fibre optic system were studied on post-mortem coronary arteries and popliteal and tibial arteries of amputated limbs. Vaporisation of atheromatous plaques was consistently obtained with energies of 300 to 600 joules associated with perfusion of the vessel with dilated blood (3 g/100 ml of haemoglobin) at a flow rate of 20 ml/min. Protection of the arterial wall was ensured by introducing the fibre aortic system through a balloon catheter and by cooling with the perfusion liquid. The reproducibity of these results in the absence of major arterial wall damage, and the facility of manipulation of the fibre optic system due to its flexibility and narrow diameter, encouraged us to use this method clinically. The first three applications on peripheral arteries (femoral and popliteal arteries) confirmed that this method of arterial disobliteration can be used with a certain degree of efficacy with only a slight risk of arterial perforation. Further studies are essential to improve the degree of laser penetration of the arterial obstruction and to increase the diameter of the tunnel of recanalisation.

Arterial Occlusive Diseases↗