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

Flow support catheter for prolonged maintenance of coronary blood flow

A newly designed flow support catheter with a supporting wire mesh cage which can be expanded into a tubular configuration and then readily reduced was evaluated in mongrel dogs. Regional myocardial blood flow (RMBF) was measured using the radioactive microsphere technique in the area of both balloon-denuded instrumented and control non-instrumented coronary arteries following placement of either a fixed-wire or a higher profile rapid exchange flow support catheter. At 5, 20, and 180 min following delivery and expansion of either device, RMBF was not significantly different in left ventricular subepicardium and subendocardium perfused by the instrumented vs. the control coronary arteries. Angiography demonstrated widely patent instrumented arteries in 15/18 dogs; in no dog was side branch occlusion observed. Significant cage thrombus deposition was seen angiographically in 3 animals causing temporary total coronary occlusion in 1. Following reduction and removal of the flow support catheter, vessel patency was present in all dogs. The flow support catheter is an effective endovascular stenting device capable of providing structural arterial support, while simultaneously maintaining distal coronary blood flow. It is envisioned that the primary application of this catheter will be to enable primary salvage of vessels acutely injured during coronary angioplasty, by "tacking up" intimal flaps for an extended period. It may also provide a bridge to emergency surgical revascularization.

Emergency coronary artery bypass surgery following failed balloon angioplasty: role of the internal mammary artery graft

During a 4-year period (1986-1989), 3,502 patients had percutaneous transluminal coronary angioplasty (PTCA) in our institution. One hundred nineteen (3.4%) patients required emergency coronary artery bypass graft surgery (CABG) because of abrupt vessel closure following PTCA. Factors associated with vessel closure included lesion angulation greater than or equal to 90 degrees (p less than 0.007), the presence of thrombus (p less than 0.02), or a long (greater than or equal to 2 cm) lesion (p less than 0.03). Of these 119 emergency CABG patients, 108 (91%) arrived in the operating room in a stable condition (group I) and 11 (9%) were in cardiogenic shock (group II). Five (45%) of the group II patients were admitted to the hospital with an acute myocardial infarction and all 11 patients had a higher incidence of multivessel disease (p less than 0.05) and lower left ventricular ejection fraction (p less than 0.001) than group I patients. The overall surgical mortality was 10.1%; however, in group I the mortality was 5.6% and in group II it was 54.5% (p less than 0.001). The vessel that abruptly closed ("culprit vessel") was the left anterior descending (LAD) in 60%, the right coronary artery in 27%, and the left circumflex in 13%. The internal mammary artery was utilized to bypass the culprit artery in 51 (43%) patients, including 50% of the culprit LADs. With group I culprit LAD patients, when the left IMA was the bypass conduit, there were no hospital deaths nor strokes and there was a 6.3% incidence of perioperative infarction.

Directional coronary atherectomy for failed angioplasty due to occlusive coronary dissection

We describe a case in which coronary balloon angioplasty failed to improve sequential lesions and resulted in a long area of dissection between the stenoses. Directional coronary atherectomy of the occlusive dissection produced excellent angiographic improvement to achieve a successful result and avoid the need for urgent coronary bypass surgery. Directional coronary atherectomy represents a potentially useful treatment for PTCA-induced coronary dissection.

Interventional cardiology techniques for coronary artery disease

This review updates and extends observations made in this journal in March 1988. The focus then was on percutaneous transluminal coronary angioplasty and the clinical results of its practical application. A concern was expressed that science lagged in solving the major problems of rethrombosis and restenosis. The NHLBI Bypass Angioplasty Revascularization Investigation (BARI) study was still in the planning phase. In 1991, the scene has changed. Interventional cardiology now embraces a multitude of different catheter devices--angioplasty, atherectomy, laser, stents. Basic scientists are increasingly involved in addressing the restenosis issue. Our national heart meetings are increasingly oriented towards molecular biology approaches to solving the remaining problems. The BARI trial has nearly completed patient entry, and we eagerly await its results. The cardiologist and surgeon are faced with increasingly complex decisions with respect to interventional technologies, involving not only whether to use them, but which ones.

Effect of angiotensin converting enzyme inhibition on the incidence of restenosis after percutaneous transluminal coronary angioplasty

To determine whether angiotensin converting enzyme (ACE) inhibition may reduce the incidence of restenosis after percutaneous transluminal coronary angioplasty (PTCA), we retrospectively identified 322 consecutive patients who underwent a successful procedure from June 1988 to December 1989. No patients developed chest pain, ST segment elevation, positive cardiac enzymes, or other evidence of abrupt vessel closure following the PTCA. All patients received intravenous heparin after PTCA and aspirin was begun on the day prior to PTCA. Patients were separated into two groups: those at hospital discharge incidentally treated for hypertension or heart failure with ACE inhibitors (n = 36), and those treated with a drug regimen which did not include ACE inhibitors (n = 286). The two groups were similar with respect to age (61 +/- 13.5 vs. 60 +/- 12.5, p = NS) and other demographic characteristics. Restenosis, defined as the presentation to a physician with symptoms of angina within 6 months of the PTCA and the finding on repeat catheterization of a significant restenosis at the site of the PTCA, occurred in 30% of the patients who were discharged on a drug regimen which did not include ACE inhibitors vs. 3% (p less than .05) in those treated with an ACE inhibitor. Thus, it appears that the use of ACE inhibitors may significantly reduce the incidence of restenosis after successful PTCA.

Advances in coronary interventional techniques

The practice of catheter interventional techniques for coronary artery disease is just 14 years old. Many approaches are being applied, including balloon and rotational angioplasty devices, atherectomy catheters, lasers, and stents. Considerable efforts are being made developing, marketing and comparing these technologies. Restenosis is demanding more attention amongst clinical and basic scientists. The pathophysiology of this frequent and irksome complication is still poorly understood. A number of trials are comparing strategies of PTCA against medicine and surgery. In the United States, the Bypass Angioplasty Revascularization Investigation (BARI) of PTCA versus surgery for patients with multivessel disease has nearly completed patient entry; the preliminary results are eagerly awaited. Patients in nearly all countries are benefiting from these new technologies. Their development and evaluation has been most active in North America, Europe and Japan but many of them are being clinically applied in nearly all countries. Their cost and complexity present special challenges for funding, training and evaluation.

Laser balloon angioplasty: clinical, angiographic and histologic results

Laser balloon angioplasty combines conventional coronary angioplasty with laser energy to transiently heat vascular tissue. Laser balloon angioplasty, was performed in 21 patients (aged 56 +/- 13 years), including 10 patients treated urgently after acute failure of conventional angioplasty and 11 patients treated with elective laser balloon angioplasty. Immediately after conventional angioplasty, laser doses (1 to 10 doses of 205 to 380 J each) were delivered during inflation of the laser balloon to a pressure of 4 atm. Seven (70%) of 10 patients with acute failure of conventional angioplasty were successfully treated with laser balloon angioplasty, but 3 (30%) were unsuccessfully treated with the laser procedure and required emergency coronary artery bypass surgery. In all three failures, the 3 mm laser balloon angioplasty catheter was not the optimal size for the vessel. In the 11 patients treated with elective laser balloon angioplasty (reference diameter 2.94 +/- 0.22 mm), the minimal luminal diameter increased from 0.45 +/- 0.25 to 1.85 +/- 0.46 mm after conventional angioplasty and to 2.44 +/- 0.29 mm after laser balloon angioplasty (p less than 0.001). This corresponded to a decrease in diameter stenosis from 84 +/- 9% before to 35 +/- 16% after conventional angioplasty and to 15 +/- 10% after laser balloon angioplasty (p less than 0.001). There were no instances of myocardial infarction, emergency coronary artery bypass surgery or death and no acute complications related to delivery of laser energy in this group. Follow-up coronary angiography was performed 5.5 +/- 1.1 months after laser balloon angioplasty in 18 patients discharged from the hospital after a successful procedure. Ten patients (56%) had angiographic restenosis, defined as recurrent diameter stenosis greater than 50%. Six patients were subsequently treated by directional coronary atherectomy, which revealed intimal proliferation indistinguishable from that in patients with restenosis after conventional angioplasty. In conclusion, laser balloon angioplasty may be effective in sealing severe coronary dissections and reversing abrupt closure associated with failed conventional angioplasty. After uncomplicated conventional angioplasty, laser balloon angioplasty improves immediate luminal dimensions, but restenosis appears to be mediated by intimal hyperplasia, similar to that seen after conventional angioplasty.

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.