Jo Habets

In vivo evaluation of the Hydrolyser hydrodynamic thrombectomy catheter.

PURPOSE The authors evaluated a 7-F double-lumen thrombectomy catheter (Hydrolyser) in vivo. MATERIALS AND METHODS To evaluate efficacy, thrombectomy was performed 1, 4, or 8 days after local denudation in peripheral arteries (n = 18) and veins (n = 29) of nine goats. To evaluate safety, the reaction of the vessel wall to a functioning and nonfunctioning Hydrolyser catheter was evaluated in the peripheral arteries and veins of three goats 10 days after the procedure. RESULTS Reopening was achieved in all vessels with residual thrombus in 11% of arteries (two of 18) and 55% of veins (16 of 29). Slight intimal thickening was observed, but no difference was seen between the passage of a functioning versus nonfunctioning catheter. CONCLUSIONS The Hydrolyser device can remove intravascular thrombus up to 8 days after induction. There was no difference in vessel wall reaction after the passage of a functioning and nonfunctioning catheter.

Comparison of arterial wall reaction after passage of the Hydrolyser device versus a thrombectomy balloon in an animal model

PURPOSE This study was designed to compare the reaction of the vessel wall after application of the Hydrolyser hydrodynamic thrombectomy device to the reaction after use of a balloon thrombectomy catheter. The influence of the vessel inner diameter on vessel wall reaction was evaluated after passage of the Hydrolyser. MATERIALS AND METHODS After measurement of the vessel inner diameter with intravascular ultrasound (US), 102 segments of femoral and carotid arteries of goats were treated with one of the following four procedures: passage of the intravascular US catheter alone; passage of the Hydrolyser without or with an activated jet; or passage of an inflated thrombectomy balloon. Histologic evaluation was performed after 3 weeks. RESULTS Intimal thickening (more than five cell layers of neointima) 3 weeks after treatment occurred more frequently after passage of the balloon than after any of the other procedures (P < .001). For vessels with a diameter of 3-4 mm, 4-5mm, or more than 5 mm, no significant difference in vessel wall reaction was observed following Hydrolyser passage. CONCLUSION In this model, passage of the Hydrolyser device resulted in less intimal reaction compared with the thrombectomy balloon.

New biocompatible polymer surface coating for stents results in a low neointimal response

Clinical studies indicate a more pronounced endothelial response after stent implantation than after balloon inflation. This might be related to the metal surface of the stent, and therefore it is speculated that coating of the stent might partially prevent hyperplasia. One coated and one noncoated Palmaz-Schatz stent were implanted in two separate coronary arteries of seven pigs. The coating was composed of methylmethacrylate (MMA) (hydrophobic, 70 mol %) and 2-hydroxyethyl methacrylate (HEMA) (hydrophilic 30 mol %). After sacrifice (3 weeks), cross sections were made of the stented areas. Vessel wall reaction was calculated both independently and dependently of local vessel wall injury due to the stent struts. Overall, vessel wall reaction of the coated stents was lower than that of the noncoated stents. The degree of hyperplasia was linearly related to the degree of stent-induced vessel wall injury. Analyses of all the struts showed that significantly less hyperplasia occurred in the coated versus noncoated stents. In this porcine coronary artery model, the MMA/HEMA stent coating resulted in significantly reduced vessel wall response. However, it remains to be determined whether this favorable outcome will also be present in humans.

Distal Embolization during Thrombectomy with Use of the Hydrolyser (Hydrodynamic Thrombectomy Catheter): In Vitro Testing

PURPOSE To evaluate distal embolization while using the Hydrolyser (hydrodynamic thrombectomy catheter) with special attention to the severity of the stenosis and temporary distal or proximal flow obstruction. MATERIALS AND METHODS The Hydrolyser procedure was assessed in plastic tubes (5-8 mm) with a 70% or 90% diameter stenosis with or without temporary distal flow obstruction and a 72-hour-old clot proximal to the stenosis. The weight of the embolized particles was established after passage through filters of 1,000, 500, 100, and 10 microm. To evaluate the influence of the absolute inner diameter of the stenosis 1.0-, 2.1-, and 3.0-mm stenoses were compared in 10-mm tubes. RESULTS Thrombus removal was greater than 99.9% in all but one of the cases in the 5-8-mm tubes. Embolization with a weight of more than 1 mg was only found in tubes with a relative stenosis of 70% and a stenosis inner diameter of greater than 1.5 mm. There was a positive relationship between inner diameter of the stenosis and the amount of distal embolization. In the presence of a proximal or distal temporary flow obstruction during thrombectomy, no distal embolization greater than 1 mg was found. CONCLUSION In this in vitro study, the Hydrolyser thrombectomy device demonstrated minimal distal embolization. The amount of distal embolization that did occur was related to the absolute stenosis diameter and could be prevented by a severe distal stenosis and/or a temporary proximal or distal flow obstruction.

A New Stimulation Protocol for Cardiac Assist Using the Latissimus Dorsi Muscle

When treating severe cardiac failure with dynamic cordiomyoplasty, knowledge about the optimal way of stimulating the latissimus dorsi (LDJ muscie is of obvious importance. We evaluated a new stimulation protocol in/our goats using in situ electrical stimulation of the left LD muscle. Stimulation was started using a burst of two pulses with an interpulse interval of 100 msec for 50 bursts/min. The number of pulses was increased every 2 weeks concomitant with a decrease in interpulse interval. This resulted after 12 weeks in 60 bursts/min using bursts of six pulses with an interpulse interval of 20 msec after 12 weeks. Force measurements, which were done every 2 weeks, shoived an early decrease in contraction and relaxation speed as reflected in the ripple (= interstimulus amplitude/peak force amplitude measured at 10 HzJ. Fatigue resistance increased significantly within 4 weeks of conditioning as indicated by preservation of force, positive dF/dt, and negative dF/dt. Full preservation of these variables was seen even during a 1‐hour fatigue test at the end of the conditioning period. Skeletal muscle enzyme activity as an indicator of muscle domage showed a significont rise in creatine kinase enzyme activity only on the first day following the start of LD stimulation. LD muscle biopsies revealed almost complete transformation to type I muscle fibers with a significant increase in capillary/fiber ratio when compared to the nonsfimulated LD muscle. However, some biopsies, in particular near the electrodes, did show some signs of skeletal muscle damage. Contraction characteristics of the fully transformed LD muscles were tested by increasing the number of bursts of six pulses from 50/min to 100/min. Interpulse intervals of 20 and 33 msec were used. These tests revealed thaf maximal force, positive dF/dt, and negative dF/dt was reached with 50 bursts/min using a six pulse burst with interpulse intervals of 20 msec.

Hemodynamic Effects in Acute Cardiomyoplasty of Different Wrapped Muscle Activation Times as Measured by Pressure‐Volume Relations

Abstract Background: Correct timing of mechanical interaction between wrapped latissimus dorsi muscle (LDM) and the heart during cardiac systole has been poorly understood and remains a controversial issue. Therefore, left ventricular pressure‐volume relations were analyzed in acute cardiomyoplasty while changing the synchronization delays. Methods: Effects of different delays between the sensed cardiac R wave and wrapped muscle contraction were studied in goats submitted to acute left cardiomyoplasty. Conductance and micromanometer catheters were used to evaluate hemodynamics. Systolic contribution of the wrapped muscle was studied in preassisted and assisted beats, whereas diastolic effects were studied in assisted and postassisted beats. Results: At best settings, cardiomyoplasty resulted in a significant (p < 0.05) increase in left ventricular ejection fraction (from 42.2 ± 9.2 to 56.7%± 13%), in stroke work (from 2769 ± 1140 to 4271 ± 1717 gm/m2), in dP/dt (from 1185 ± 342 to 1510 ± 285 mmHg/sec), in end‐systolic pressure (from 93.5 ± 22.5 mmHg to 97.3 ± 22.3 mmHg), and in peak ejection rate (from 282 ± 64 to 533 ± 241 mL/sec). Stroke volume showed a mean increase of 35% (from 42.2 ± 9.9 mL to 56.9 ± 20.1 mL) during assisted beats. Diastolic function was not substantially impaired at optimal stimulation delay. Incorrect timing of LD contraction resulted in suboptimal improvement or no change in comparison with unassisted hemodynamics. Conclusions: Our study documents support of cardiac performance by LDM. Incorrect timing of heart/wrapped muscle interaction led to suboptimal hemodynamic results. Muscle contraction timing is an important factor in cardiomyoplasty outcome.

Fibrin Sealant Application to Improve Cardiomyoplasty Management

Dynamic cardiomyoplasty (DC) entails the properly mobilized latissimus dorsi (LD) muscle to be wrapped around the heart and to be paced synchronously with the cardiac systole to improve cardiac performance in end-stage heart failure and restrain further ventricular dilatation. Postoperative management requires a 2-week rest period to enhance intermuscular adhesion formation. This study tested an alternative approach by applying a fibrin glue (Tissucol, Immuno, Austria) at the intermuscular interface aiming at optimal heart/LD contact and consequent earlier postoperative LD assistance. Eight goats were submitted to DC. In six animals (group A) fibrin glue was used during surgery. The biological sealant was sprayed (Tissumat, Immuno, Austria) over the contact surfaces. In this group wrapped LD stimulation was started on day 1 after surgery. In two goats (group B) no sealant was added, and standard postoperative protocol (first 2-week rest period) was followed. Both groups were extensively studied 2 weeks from surgery to detect any muscle displacement or damage in group A and to compare adhesion formation extent and strength. Group A animals showed slight hemodynamic improvement (right ventricular systolic pressure from 26 ± 6 to 30 ± 8 mmHg during assisted beats; p = 0,04), and no wrapped muscle dislocation was observed despite anticipated stimulation. At the heart/LD opposing surfaces strong and effective adhesions were detected. Histology confirmed early paced wrapped muscle viability and partial muscle fiber transformation. Group B animals showed weak adhesions in comparison with fibrin glue treated muscles. In conclusion Tissucol glue represents a valuable tool to provide optimal intermuscular fixation and allow earlier LD stimulation and related cardiac assistance.