Biomedical subjects

J R Spears

Publications and source records attributed to J R Spears.

At least 19 recordsLinked to original sources

PubMed1999

Prominent ECG repolarization changes associated with intracoronary infusion of normal saline: comparisons with alternate coronary catheter flush solutions.

Normal saline (NS) is commonly used as a coronary catheter flush solution. We tested the hypothesis that intracoronary (i.c.) infusions of lactated Ringer's solution (LR) and LR with 5% dextrose (D5LR), both of which contain potassium and calcium, would be associated with less prominent surface ECG changes compared with i.c. infusions of NS. In 34 patients, 10 mL each of NS, LR, and D5LR at 37 degrees C were infused over 5 sec into the left main coronary artery. A 12-lead ECG was recorded before, continuously during, and after each infusion. Blinded ECG analysis revealed T-wave amplitude changes > 0.2 mV in 94%, 12%, and 3% of patients with the use of i.c. NS, D5LR, and LR, respectively (P < 0.0001, NS vs. D5LR or LR). QT prolongation > 40 msec occurred in 88%, 15%, and 18% of patients with i.c. NS, D5LR, and LR, respectively (P < 0.0001, NS vs. D5LR or LR). QT dispersion was increased by > 40 msec in 26% of patients during i.c. NS infusion compared to only 3% of patients with i.c. LR and D5LR infusions (P < 0.01). In conclusion, i.c. NS infusion is associated with more marked repolarization changes as compared with i.c. LR and D5LR infusions. Since such changes may lower arrhythmogenesis thresholds, the routine use of LR as a coronary catheter flush solution should be considered. Cathet. Cardiovasc. Intervent. 48:359-364, 1999.

Adult↗

PubMed1998

Successful redeployment of an unexpanded coronary stent.

We report on treatment of a patient in whom failure to deploy the distal portion of a Palmaz-Schatz stent occurred but was not recognized. After an unstable course, the patient underwent repeat coronary angiography, at which time the stent was rewired and redilated. Full deployment of the stent with restoration of TIMI grade 3 flow was achieved. The putative cause of the problem, incomplete deployment of the stent because of inadvertent advancement of the stent delivery sheath, should be avoided, and needs to be recognized if it occurs. Crossing and redilating the stent is possible, although technically difficult.

Adult↗

PubMed1997

Aqueous oxygen: a highly O2-supersaturated infusate for regional correction of hypoxemia and production of hyperoxemia.

BACKGROUND: High levels of hyperoxemia may have utility in the treatment of regional tissue ischemia, but current methods for its implementation are impractical. A catheter-based method for infusion of O2, dissolved in a crystalloid solution at extremely high concentrations, ie, 1 to 3 mL O2/g (aqueous oxygen [AO]), into blood without bubble nucleation was recently developed for the potential hyperoxemic treatment of regional tissue ischemia. METHODS AND RESULTS: To test the hypotheses that hypoxemia is correctable and that hyperoxemia can be produced locally by AO infusion, normal saline equilibrated with O2 at 3 MPa (30 bar; 1 mL O2/g) was delivered into arterial blood in two different animal models. In 15 New Zealand White rabbits with systemic hypoxemia, AO was infused into the midabdominal aorta at 1 g/min. Mean distal arterial PO2 increased to 236+/-113 and 593+/-114 mm Hg on 1-hour periods of air and O2 breathing, respectively, from a baseline of 70+/-10 mm Hg (P<.01). In contrast, infusion of ordinary normal saline in a control group (n=7) had no effect on arterial PO2. No differences between groups (P>.05) in temporal changes in blood counts and chemistries were identified. In 10 dogs, low coronary blood flow in the circumflex artery was delivered with a roller pump through the central channel of an occluding balloon catheter. Hypoxemic, normoxemic, and AO-induced hyperoxemic blood perfusates (mean PO2, 52+/-4, 111+/-22, and 504+/-72 mm Hg, respectively) were infused for 3-minute periods in a randomized sequence. Short-axis two-dimensional echocardiography demonstrated a significant decrease (P<.05) in left ventricular ejection fraction compared with baseline physiological values with low-flow hypoxemic and normoxemic perfusion but not with low-flow hyperoxemic perfusion. CONCLUSIONS: Intra-arterial AO infusion was effective in these models for regional correction of hypoxemia and production of hyperoxemia.

Animals↗

PubMed1997

Coronary embolism complicating aortic valve endocarditis: treatment with placement of an intracoronary stent.

A 37-year-old man, who had received 3 weeks of antimicrobial therapy for aortic value endocarditis, presented with an acute anteroseptal wall myocardial infarction. Coronary angiography demonstrated occlusion of the mid left anterior descending artery, thought to have been caused by embolization of a sterile vegetation. Following failure of balloon dilation to achieve vessel patency, this was achieved by placement of an intracoronary stent.

Adult↗

PubMed1997

Laser balloon angioplasty combined with local intracoronary heparin therapy: immediate and short-term follow-up results.

Laser balloon angioplasty (LBA) has been shown to acutely increase angiographic luminal dimensions after conventional balloon angioplasty (PTCA) without a favorable impact on chronic restenosis. Experimentally, laser and thermal energy enhance binding of heparin to the injured arterial wall and to the thrombus. In view of the anticoagulant, antiproliferative, and antifibrotic activities of the drug, a pilot study was performed to evaluate the potential safety and efficacy of LBA combined with local heparin therapy. Ten patients scheduled for elective PTCA were entered in the study. In each patient, a single lesion was treated with a laser balloon and coated with a heparin film (3000 I.U. at a concentration > 100,000 I.U./gm) immediately after optimal PTCA. The mean minimum luminal diameter and mean percent stenosis of the 10 treated lesions after PTCA were 1.62 +/- 0.39 mm and 37% +/- 9%, respectively. After LBA and local heparin therapy, the mean minimal lumen diameter increased to 2.01 +/- 0.34 mm (p < 0.01) and the mean percent stenosis decreased to 20% +/- 10% (p < 0.01). Systemic heparin was discontinued immediately after the procedure in all patients. Acute or inhospital complications, either major or minor, occurred in none (0%) of the 10 patients (95% confidence interval 0% to 31%); all were discharged home on the day after the procedure. All patients remained well and free of cardiac symptoms for at least 2 months after the procedure. However, restenosis developed in six (60%) of the 10 patients (95% confidence interval 26% to 88%) 2 to 6 months after the procedure. The results suggest that LBA and local heparin therapy, with discontinuation of systemic heparin immediately after angioplasty, is a safe treatment modality that yields favorable acute angiographic results.

Aged↗

PubMed1994

Effects of thermal exposure on binding of heparin in vitro to the arterial wall and to clot and on the chronic angiographic luminal response to local application of a heparin film during angioplasty in an in vivo rabbit model.

Experimentally, heparin inhibits mechanisms that promote fibrosis, neointimal cellular proliferation, and thrombin bound to fibrin at the surface of intraluminal thrombus, but only in relatively high concentrations. A preliminary hypothesis was tested and confirmed in vitro that initial binding of 3H-heparin to mechanically injured porcine aorta is concentration-dependent over a 1,000-50,000 units/ml range (r = 0.9). The hypothesis was then tested in vitro that thermal exposure during contact of heparin to arterial tissue and to clot would enhance binding of the drug. 3H-heparin binding to clot, whole blood particulates, and washed erythrocytes was markedly enhanced by exposure to temperatures > 70 degrees C. Thermal exposure (80 degrees C x 40 s) also enhanced tissue persistence of the drug within porcine aorta subjected to a shear rate of 1,100(-1) in an annular Baumgartner chamber perfused with normal saline at 37 degrees C for 48 h. Heparin in vitro anticoagulant activity persisted after thermal exposure and binding to tissues. A new method was developed for local application of a heparin film that provides a maximum concentration with a tolerable systemic dose during an angioplasty procedure. In an in vivo rabbit model of mural fibrosis after iliac artery angioplasty, the 1-month mean angiographic luminal diameter loss (23% compared to the acute postangioplasty result by computer image analysis) in response to conventional balloon angioplasty (BA) and laser balloon angioplasty (LBA) was the same (P > 0.05). Local application of a heparin film (3,000 units at a concentration > 100,000 units/g), however, reduced the mean % loss in diameter 1 month after LBA (12%), but not after BA (29%), compared to arteries subjected to angioplasty without local heparin (P < .05). The results are consistent with the hypothesis that thermal energy enhances heparin binding to tissues and that local application of a heparin film favorably modulates arterial luminal responses to LBA, but not to BA, in this animal model.

Angioplasty, Balloon↗

PubMed1994

Modulation by beta-aminopropionitrile of vessel luminal narrowing and structural abnormalities in arterial wall collagen in a rabbit model of conventional balloon angioplasty versus laser balloon angioplasty.

This study was designed to assess the potential relationship between the late loss of angiographic luminal diameter and biochemical abnormalities of arterial wall collagen in rabbits subjected to angioplasty, and to test the hypothesis that beta-aminopropionitrile (beta APN), an inhibitor of lysyl oxidase, would inhibit such changes when administered orally for 1 mo after angioplasty. Endovascular injury was induced in rabbit iliac arteries by ipsilateral balloon angioplasty (BA) and by contralateral balloon angioplasty accompanied by exposure to continuous wave neodymium: yttrium aluminum garnet laser radiation (LBA). Computer measurement of angiographic luminal diameter demonstrated significant vessel narrowing at 1 and 6 mo after both procedures. By quantitative histology, the majority of the 1-mo loss in angiographic diameter could not be attributed to neointimal thickening. Analysis of collagen cross-linking by HPLC in collagen obtained from the LBA-injured segments of the arteries 1 mo after angioplasty revealed a significant increase, relative to values from uninjured arteries (P < 0.05), in the difunctional cross-link dihydroxylysinonorleucine (DHLNL). 6 mo after angioplasty, the content of hydroxypyridinium, the trifunctional maturational product of DHLNL, was significantly elevated in both BA- and LBA-treated arteries compared with values from uninjured arteries (P < 0.05). In animals administered beta APN, luminal narrowing at 1 mo, compared with controls, was attenuated (P < 0.01) and DHLNL content was decreased (P < 0.05) in arteries subjected to LBA, but not in arteries subjected to BA. The results suggest that lathyrogenic agents may be efficacious in favorably modulating LBA-induced alterations in vessel diameter and mural connective tissue.

Aminopropionitrile↗

PubMed1992

An in vitro evaluation of the effect of laser irradiation on the thrombogenicity of thrombus.

The effect of laser irradiation on the thrombogenicity of thrombus was evaluated by treating thrombi, formed in-vitro from canine blood, with two different doses of cw Nd:YAG laser energy at 1064 nm. The thrombi were then incubated with whole blood, and the plasma levels of fibrinogen and thrombin-antithrombin III-complexes were measured. A statistically significant decrease (p < 0.05) in the thrombogenicity was indicated by a reduction in both fibrinogen consumption and levels of thrombin-antithrombin III-complexes in the high dose group (600 joules, 100 degrees C peak temperature) in comparison to the low dose group (300 joules, 70 degrees C peak temperature) and the untreated thrombi. These findings suggest that laser irradiation of thrombus at an appropriate dose may substantially reduce its thrombogenicity and ability to modulate hemostasis.

Animals↗

PubMed1992

Percutaneous transluminal coronary angioplasty of coronary artery embolism.

A 35-yr-old woman with known valvular heart disease presented with acute myocardial infarction. Angiography demonstrated a totally occluded distal left anterior descending coronary artery. Though initially successful, angioplasty ultimately failed to maintain arterial patency, leaving a more distal total occlusion after several balloon inflations. In spite of this, PTCA possibly provided a more localized infarction via a peripheral mobilization of the embolus.

Adult↗

PubMed1992

Long-term effects of percutaneous laser balloon ablation from the canine coronary sinus.

BACKGROUND: Radiofrequency catheter ablation of left-sided accessory pathways is becoming the first line of therapy for patients with symptomatic Wolff-Parkinson-White syndrome. Nevertheless, alternative ablation techniques merit development, at least as supplementary modalities for cases in which conventional ablation approaches may prove unsuccessful. We recently reported the short-term results with transcatheter laser balloon ablation from the coronary sinus in a canine model, proving that the procedure is feasible for the potential ablation of left-sided accessory pathways. We now report the effects of percutaneous transcatheter laser balloon ablation in a chronic canine model. METHODS AND RESULTS: Twenty adult mongrel dogs were studied. After baseline coronary arteriography, left ventriculography, and coronary sinus angiography were obtained, 15 dogs received two or three consecutive laser doses from the coronary sinus of 30-40 W for 15-30 seconds, for a total cumulative energy of 1,200-2,400 J. The five remaining animals underwent a procedure consisting of balloon sham inflation without laser exposure and served as controls. After a mean follow-up of 6 weeks, the angiographic procedures were repeated, and the animals were killed. The mean extent of the fibrotic lesion was 15 mm long, 6 mm wide, and 4.5 mm deep and involved the coronary sinus wall, atrium, and, frequently, the summit of the posterior left ventricular wall. Six animals (four in the study group and two in the control group) showed asymptomatic narrowing of the coronary sinus lumen but always with total angiographic reconstitution due to extensive collateral circulation. The circumflex artery and mitral valve were intact angiographically and histologically in all animals. CONCLUSIONS: Percutaneous transcatheter laser balloon ablation via the coronary sinus produces a lesion that may be anatomically well suited for left-sided accessory pathway ablation. Although coronary sinus narrowing may occur, adverse physiological effects are unlikely due to the development of extensive collateral circulation. Systematic clinical studies of this new approach to catheter ablation appear warranted.

Animals↗

PubMed1991

Laser balloon angioplasty: potential for reduction of the thrombogenicity of the injured arterial wall and for local application of bioprotective materials.

Mitigation of adverse biologic reactivity after balloon angioplasty is necessary before the incidence of restenosis can be appreciably reduced. A brief review of experimental evidence supports the hypothesis that the thrombogenicity of the injured arterial wall can be reduced by a suitable level of thermal denaturation or cross-linking of thrombogenic proteins. In addition, the concept of local pharmacologic therapy, which can be provided with laser balloon angioplasty at the site of arterial injury, is introduced. Preliminary in vitro and in vivo data suggest that guide catheter-injected albumin-heparin conjugates fabricated as water-insoluble microspheres remain adherent to the injured luminal surface and deeper arterial layers after physical trapping by the inflated balloon and subsequent laser/thermal exposure. The combination of initially adequate luminal morphology, reduction of the thrombogenicity of the injured arterial wall and application of local pharmacologic therapy with laser balloon angioplasty may eventually prove helpful in reducing the incidence of restenosis.

Angioplasty, Laser↗

PubMed1991

Laser balloon angioplasty.

Unlike conventional transluminal percutaneous angioplasty (PTCA), which applies only intraluminal pressure, laser balloon angioplasty (LBA) employs simultaneous heat and pressure to reopen heavily occluded arterial lumens. The circumferential irradiation of Nd:YAG (1.06 microns) laser light is directly absorbed by approximately 1 to 2 mm of arterial tissue immediately adjacent to the inflated balloon. Such heating by LBA is able to seal disrupted luminal flaps, thermally remodel the luminal surface topology, reduce arterial recoil, selectively (partially) dehydrate thrombus, and possibly even reduce thrombogenicity at atherosclerotic sites. Criteria for successful LBA are defined based on earlier fundamental in vitro experiments to determine effective welding temperature, laser power doses, and exposure period; in addition, the derivation and validity of a three-part optical-thermal model and its application in parametric dosimetry analysis are presented. Though the lumen remodeled by LBA is acutely satisfactory, recurrence of the lesion is problematic chronically. Because of this, LBA is currently most useful as an adjunctive procedure whenever PTCA fails to produce optimal results or causes acute vessel closure. Perhaps, another potential application of the LBA system is to aid localized delivery of pharmacologic agents and their thermal adhesion to superficial tissue at angioplastied sites.

Angioplasty, Laser↗

PubMed1990

Percutaneous transcatheter laser balloon ablation from the canine coronary sinus: implications for the Wolff-Parkinson-White syndrome.

Transcatheter direct current electrical shocks for ablation of left-sided accessory pathways in Wolff-Parkinson-White patients have led to serious complications. We report the feasibility of percutaneous transcatheter laser balloon ablation of left-sided accessory pathways from the coronary sinus using a 1,064-nm, continuous wave Nd:YAG laser triple lumen catheter with an optical fiber terminating in a cylindrical diffusing tip within a 2-cm-long, 3-mm-diameter balloon transparent to Nd:YAG laser radiation. In eight mongrel dogs (18 to 31 kg), the laser balloon catheter was positioned via an 8 French guide catheter in the distal and proximal coronary sinus. During balloon inflation, two to three consecutive laser doses of 30 W x 20 sec were applied to each site (cumulative energy, 1,200 to 1,800 J). Coronary angiography, left ventriculography, and coronary sinus injection were performed before and after laser exposure. After percutaneous transcatheter laser balloon ablation, there was no evidence of mitral regurgitation, left circumflex artery, coronary sinus obstruction, or perforation. Coagulation necrosis and/or polymorphonuclear infiltrates involving the atrioventricular groove and left atrial wall over a mean length of 17 mm were present in all eight dogs sacrificed 6 +/- 1 hr postablation. In conclusion, percutaneous transcatheter laser balloon ablation from the coronary sinus is free of immediate major complications and may be feasible for potential interruption of left-sided accessory pathways.

Animals↗

PubMed1990

Percutaneous coronary laser balloon angioplasty: initial results of a multicenter experience.

A multicenter clinical trial was initiated to test the potential safety and short-term efficacy of a percutaneous coronary application of laser balloon angioplasty, which has been shown experimentally to alleviate the common causes (dissection, recoil, thrombus) of suboptimal luminal results of conventional balloon angioplasty. Fifty-five patients, the majority (62%) of whom had relatively high risk lesions, were treated in 10 centers with a laser balloon that was identical in size (3 x 20 mm) to a balloon used for conventional balloon angioplasty performed on the same lesion immediately before laser balloon angioplasty. One or more neodymium:yttrium aluminum garnet (Nd:YAG) (1,060 nm) laser doses of 250 to 450 J were each delivered over a 20 s duration per exposure. Immediately and 1 day after laser balloon angioplasty no significant adverse effects on the arterial lumen were noted in any patient. By computerized image analysis of cineangiograms initial conventional balloon angioplasty failed to achieve a minimal luminal diameter greater than 1.5 mm in 14 patients (25%), including 3 patients with acute closure. However, after subsequent laser balloon angioplasty, minimal luminal diameter exceeded this value in all patients including this subgroup. Overall, minimal luminal diameter increased from 1.74 +/- 0.46 mm after conventional balloon angioplasty to 2.32 +/- 0.31 mm after laser balloon angioplasty (p less than 0.001) with no change found on 1 day and 1 month follow-up angiograms. Thus, laser balloon angioplasty is a safe, effective procedure for improving luminal dimensions after conventional balloon angioplasty.

Adult↗

PubMed1990

Laser balloon angioplasty. A new approach to abrupt coronary occlusion and chronic restenosis.

Abrupt coronary occlusion and long-term restenosis continue to be the major problems associated with percutaneous transluminal coronary angioplasty (PTCA). Laser balloon angioplasty (LBA) is a technique designed to potentially alleviate these problems by sealing arterial dissections, smoothing the luminal surfaces, dehydrating thrombi, and reducing the elastic properties that tend to recoil the stretched artery to its original state. During LBA, laser energy is delivered circumferentially by a 100-microns optical fiber that terminates in a central diffusing tip within an angioplasty balloon. LBA is performed for 20 seconds during the final inflation of the angioplasty balloon. Achieved with decremental ramped laser dosimetry, Nd:YAG laser energy has been shown to be effective in welding experimental arterial dissections over a therapeutic temperature range of 95 degrees-120 degrees C. LBA treatment of rabbit iliac arteries has been superior to balloon angioplasty in inhibiting elastic recoil and causing acute and long-term luminal increment. LBA has also been effective for sealing acute dissections in atherosclerotic rabbit iliac arteries. Additionally, in a canine model, safety in the coronary circulation has been shown, that is, even at 1 month after LBA, angiography demonstrated a cast of the LBA balloon without luminal compromise. Since March 1988, more than 250 patients with symptomatic coronary artery disease have been treated with LBA with nearly uniform clinical success, including frequent reversal of abrupt closure. LBA seems to be a safe modality that may decrease the need for emergency operative procedures and late coronary revascularization after PTCA.

Angiography↗

PubMed1989

Laser balloon angioplasty versus balloon angioplasty in normal rabbit iliac arteries.

Reduction of vascular recoil is an important goal of laser balloon angioplasty (LBA), wherein Nd:YAG laser radiation is delivered radially during balloon inflation. To define the acute and chronic effects of LBA on the normal arterial lumen in comparison with those of balloon angioplasty (BA), 36 New Zealand White male rabbits (3-4 kg) were subjected to LBA of an external iliac artery and to BA of the contralateral artery with two 1-minute balloon inflations. During LBA, which was performed during the second balloon inflation, either 300 (n = 26) or 176 (n = 10) J were delivered to achieve high and moderate laser doses, respectively, in different LBA groups. Angiography was performed pre- and post-LBA/BA and subsequently at intervals of either 1, 2, 7, 28, 48, or 223 days. Automated analysis of digitized images was used to measure lumen diameter. No instance of perforation or thrombosis occurred. LBA-treated arteries acutely showed an increase in mean diameter over baseline (+ .5 mm, P less than .01) and that of BA-treated arteries (+ .4 mm, P less than .01). While arteries treated with the high laser dose showed a loss of the initial gain in lumen diameter by 1 month, caused by both extravascular fibrosis of the thinwalled (less than 0.1 mm) artery and mild neointimal proliferation which were not reduced by daily administration of aspirin in seven rabbits, arteries treated with the moderate laser dose retained the increment in mean diameter at 1 month over that of BA-treated arteries (+ .5 mm, P less than .05). Thus, unlike BA, LBA increases luminal diameter acutely and, at a moderate laser dose, chronically.

Angioplasty, Balloon↗

PubMed1988

Laser balloon angioplasty: effect of tissue temperature on weld strength of human postmortem intima-media separations.

Dehiscence of portions of atheromatous plaques fractured during percutaneous transluminal coronary angioplasty may contribute to both abrupt reclosure and gradual restenosis. Laser balloon angioplasty has been shown to be effective in welding human plaque-arterial wall separations in vitro by heating tissues with a Nd:YAG laser during balloon inflation. To define the potentially useful therapeutic range of tissue temperature required to achieve thermal welds, 220 1-cm diameter discs of human postmortem atheromatous aortic tissue, the intimal plaque of which had been separated from the media, were exposed to 3-25 watts of Nd:YAG laser radiation delivered over a 12-mm2 nominal spot size for 20 seconds via a 400-micron core optical fiber. As measured with a thermistor, adventitial temperature reflected the temperature at the plaque-media junction to within 10 degrees C. The degree of tissue temperature elevation was related to delivered energy, while effective tissue penetration increased to maximum depth of 3 mm at the highest power density. Strength of tissue welds was defined as the force required to shear opposing layers of welded segments. Adventitial tissue temperatures below 80 degrees C were not associated with appreciable welds, while equilibrium temperatures between 95 degrees C and 140 degrees C were consistently associated with effective mean weld strengths, which increased linearly from 25 to 110 g, respectively. Temperatures greater than 150 degrees C were associated with rapid tissue dehydration and charring. These data suggest that the therapeutic range of tissue temperature that provides effective thermal fusion of intima-media separations is broad and that the depth and degree of thermal coagulation can be controlled by manipulation of laser energy delivery.

Angioplasty, Balloon↗

PubMed1988

Laser balloon angioplasty: effect of constant temperature versus constant power on tissue weld strength.

Thermal fusion of intimal plaque with the arterial wall during coronary balloon angioplasty may significantly reduce the incidence of abrupt closure and may reduce the occurrence of delayed restenosis by improvement of luminal size and shape. Although Nd:YAG laser energy has been shown to be effective in the thermal fusion of plaque-arterial wall separations in vitro, the most efficient manner of energy delivery for rapid achievement of therapeutically useful equilibrium tissue temperature during laser exposure has not been defined. A comparison of weld strength achieved was therefore made between two formats of laser delivery: constant power vs. decremental power with an initial high dose followed by the minimal serial decrements necessary to maintain tissue temperature constant for 15 seconds. One hundred sixty-six tissue discs of human postmortem aorta of 11 mm diameter were studied. Intimal plaque was separated from the media, the two layers were juxtaposed, a force of 4 pounds was applied, and a fiberoptic-delivered laser beam was directed perpendicular to the tissue over a 3-mm-diameter nominal spot size. Weld strength was measured as the shear force required to separate completely the two tissue layers. The mean weld strength (75 g) achieved by use of the decremental power format was significantly higher (P less than .01) than the mean strength (32 g and 56 g) achieved by using constant power for 20 and 30 seconds, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗