In the past two years, we have been using two new technologies that may have significant impact on the practice of vascular surgery. The first, angioscopy, allows the vascular surgeon to see the endothelial surface of blood vessels in considerable detail at points remote from the incision. The second technology, laser angioplasty, may allow restoration of blood flow in obstructed vessels, with catheters inserted either percutaneously or intraoperatively. This article intends to give the vascular surgeon an overview of these two new fields. Our group at Cedars-Sinai Medical Center has developed the application of vascular endoscopy,1Grundfest WS Litvack F Sherman T et al.Delineation of peripheral and coronary detail by intraoperative angioscopy.Ann Surg. 1985; 202: 395-400Crossref Scopus (75) Google Scholar, 2Litvack F Grundfest WS Lee MS et al.Angioscopic visualization of blood vessel interior in animals and man.Clin Cardiol. 1985; 8: 65-70Crossref PubMed Scopus (47) Google Scholar using endoscopes from 2.8 to 0.85 mm in outer diameter to view the interior of blood vessels from 1 mm to 1 cm in diameter. For the smallest vessels we use the 1.5 to 0.85 mm outer diameter endoscopes (American Edwards, Santa Ana, Calif.). These angioscopes contain 5000 to 8000 imaging fibers, a concentric ring of lumination fibers, and are enveloped by a flexible plastic catheter housing. For medium-sized vessels we have used 1.8 and 1.4 mm outer diameter endoscopes (Olympus, Rye, N.Y.). Both of these angioscopes have a central image bundle, a surrounding concentric ring of illumination fibers and are sheathed in a polyvinyl chloride jacket. For imaging the inside of larger arteries we have used 2.8, 2.5, and 1.9 mm outer diameter scopes (Trimedyne Inc., Santa Ana, Calif.). None of these devices has angulation systems. Illumination is provided by a 1000 watt xenon light source (Storz Corp., Los Angeles, Calif.). Light is gathered from the vessel lumen by a distal lens and focused on the optical bundle. The bundle transmits the image via a specially constructed video-endoscopic coupler to a low-noise, high-gain, three-tube camera (Sharp, XC801RP). We viewed vessel images on a high-resolution monitor (Sony PVM 1960) and recorded them on¾ inch video tapes. Before use all angioscopes are tested for minimum focus, spatial resolution, and flaws in the jacketing. The spatial resolution of these devices exceeds 200 μm at 5 mm; a minimum focus distance ranges from 2.0 to 6.5 mm. The longer focal lengths are not usable in small vessels. We use two methods to obtain a blood-free field during the imaging process. At the time of coronary bypass during cardioplegic arrest, crystalloid cardioplegia is infused through either the aortic root or at the anastomotic site. In peripheral vessels control of blood flow is obtained in the usual fashion and the angioscopes are inserted at either the proximal or distal site of anastomosis or through the graft. A pressurized system is used to infuse crystalloid solution above systemic pressure to obtain a clear field. Scopes that do not contain their own irrigating system are introduced with either a concentric or coaxial irrigating system; this usually consists of a No. 9 French introducer catheter with a side port or an 18- or 16-gauge intravenous catheter 5 inches in length. To date we have inserted angioscopes in 68 patients at the time of coronary bypass surgery and in 38 patients at the time of peripheral vascular surgery. In these patients we have performed 156 angioscopic inspections, including 31 new anastomoses, 10 old grafts, and 10 in situ vein grafts. We have successfully visualized vessels in approximately 80% of the patients studied. The major cause of image loss was the inability to deliver sufficient irrigation to the field of view. A typical angioscopic image is shown in Fig. 1.This image shows an atherosclerotic plaque in the lumen of a patient with stable triple-vessel coronary artery disease. The intimal surface is smooth, white, and glistening. Fig. 2 shows a typical anastomosis of a polytetrafluoroethylene graft to a suprageniculate femoral artery.Fig. 2This is the typical appearance of an angioscopic image of a normal sutured anastomosis. Suture line of 5-0 Prolene can be seen as a series of regular lines radiating around oval anastomoses. Both proximal and distal lumens are widely patent.View Large Image Figure ViewerDownload Hi-res image Download (PPT)The anastomosis has a smooth oval appearance and the suture line of 5-0 polypropylene (Prolene) is readily visible. In contrast, Fig. 3 shows an anastomosis with an almost totally obstructed distal lumen.Fig. 3This angioscopic view of a polytetrafluoroethylene graft to the suprageniculate popliteal artery reveals an almost totally occluded distal lumen. The more proximal aspect has incorporated a large ulcerated atheroma into the suture line. This information permitted the surgeon to revise the anastomoses.View Large Image Figure ViewerDownload Hi-res image Download (PPT)A large atheroma with attached thrombotic debris has been incorporated into the anastomotic suture line. The angioscopic image of distal obstruction and ulcerated irregular anastomotic margins was sufficient evidence to prompt intraoperative revision of this anastomosis. We have found that angioscopy is able to localize nondisrupted venous valves at the time of in situ saphenous vein bypass grafting. Fig. 4 shows such a valve found after presumed valve disruption by a valvulotome.These nondisrupted valve leaflets are difficult to appreciate angiographically. Devices that will permit endoscopically visualized valve resection are under development. These angioscopic images give the surgeon the option to directly visualize the results of his work, to inspect suture lines, and to evaluate the patency of the newly created lumen. Angioscopic images provide an intraluminal view of vascular pathologic features.3Grundfest WS Litvack F Sherman T et al.Definition of new pathophysiologic mechanisms and altered decisions: an outcome of intravascular angioscopy.J Am Coll Cardiol. 1986; 2: 153aGoogle Scholar Fig. 5 depicts the lumen of a left anterior descending (LAD) artery in a patient with unstable rest angina.There is a large thrombus partially occupying the lumen. This thrombus was not recognized angiographically. The finding of partially or totally occlusive thrombus was consistent in all patients studied who had unstable angina. Angiography was unable to detect thrombus in many of these cases.4Sherman C Litvack F Grundfest W et al.Coronary angioscopy in patients with unstable angina pectoris.N Engl J Med. 1986; 15: 913-919Crossref Scopus (675) Google Scholar In peripheral and coronary arterial systems differentiation between arterial thrombus and atherosclerotic plaque was easily made by angioscopy but was difficult by angiography. In two peripheral cases, presumed chronic total occlusions were angioscopically observed to be thrombotic in nature. Fig. 6 shows the lumen of an atherosclerotic LAD artery in a patient with accelerated angina.Fig. 6This angioscopic image was obtained from left anterior descending artery of a patient with accelerated angina. Angiography showed only a smooth 50% stenosis. Angioscopically we found a circumferentially ulcerated irregular lesion with subintimal hemorrhage. Cellular debris has accumulated on the surface of this lesion.View Large Image Figure ViewerDownload Hi-res image Download (PPT)The intimal surface is circumferentially ulcerated and subintimal hemorrhage is present and radiates outward from the base of the ulcer. This angioscopic picture is typical of the pathologic features seen in accelerated angina.4Sherman C Litvack F Grundfest W et al.Coronary angioscopy in patients with unstable angina pectoris.N Engl J Med. 1986; 15: 913-919Crossref Scopus (675) Google Scholar Information that altered surgery included misplaced sutures at anastomotic sites, unsuspected partial occlusion of vascular lumens, and thrombi at newly created peripheral anastomoses. During in situ saphenous vein bypass grafting we frequently detected residual nondisrupted valves (7 of 10 cases). In patients with renal compromise, detailed angioscopic inspection allowed the surgeon to cancel the completion angiogram. Table I lists the changes in operative procedure resulting from angioscopy.Table IChanges in operative procedures on the basis of angioscopyOperative changePeripheralCoronaryGraft revision11Revised suture line42Thrombus extraction30Retained vein valves (in situ)70Deleted angiogram20Intraoperative dilatation02________ Total changes175 Open table in a new tab Angioscopy also provided the means to visualize the vessel lumen in patients with ischemic coronary syndromes. The angioscopically observed pathologic features in these unstable syndromes is substantially greater than that recognized at routine postmortem examination.5Forrester JS, Litvack F, Grundfest W, Hickey A. New insights into the role of thrombus in the pathogenesis of acute and chronic coronary heart disease. Perspectives Circ (In press.)Google Scholar In patients with accelerated angina we observed intimal ulcers and associated platelet aggregates in the coronary arteries that were believed to be responsible for the anginal syndrome as established by electrocardiographic evidence. In patients with unstable rest angina the “offending artery” had thrombus partially or totally occupying the lumen. Thus angioscopy gives us new insight into the pathophysiology of clinical disease states.5Forrester JS, Litvack F, Grundfest W, Hickey A. New insights into the role of thrombus in the pathogenesis of acute and chronic coronary heart disease. Perspectives Circ (In press.)Google Scholar Angioscopy provides high-resolution, clinically relevant images that can be obtained by no other method. Information obtained by angioscopy allows a surgeon to evaluate the native vascular pathology and the intraoperative therapy.6Chaux A Lee M Blanche C et al.Intraoperative coronary angioscopy: technique and results in the initial 58 patients.J Thorac Cardiovasc Surg. 1986; 92: 972-976PubMed Google Scholar Unrecognized technical errors may be the cause of early graft failures; a significant portion of in situ veins subjected to angioscopy in this series had intact valve leaflets. Our angioscopic experience suggests that intimal disease, either ulceration and accumulated cellular debris or subsequent thrombus formation, is the underlying cause of acute ischemic syndromes.5Forrester JS, Litvack F, Grundfest W, Hickey A. New insights into the role of thrombus in the pathogenesis of acute and chronic coronary heart disease. Perspectives Circ (In press.)Google Scholar To determine whether angioscopy enhanced long-term patency by detecting technical errors, a more detailed long-term study is in progress. When angioscopic information can be easily obtained in the operating room, it is likely to gain acceptance by the vascular surgeon. However, present devices require a significant effort to use on a routine basis. To become clinically applicable, simplified irrigation and delivery systems must be constructed. The development of percutaneous angioscopy would add a new dimension to the diagnosis and treatment of vascular disease. Although we have successfully performed percutaneous coronary artery angioscopy in the laboratory, human application awaits the construction of appropriate catheters, irrigation, and steering systems. A typical laser consists of an energy source, a chamber with mirrors at each end, and an active medium. The active medium can be solid, liquid, or gas. Thus, an argon ion laser uses argon gas and the Nd:YAG laser uses a neodymium yttrium aluminum garnet crystal as its active medium. When sufficient energy is delivered into the cavity containing the active medium, the molecules of the solid, liquid, or gas become excited. In the process of releasing energy and returning to the ground or unexcited state, the activated molecules emit photons of light. As the photons are reflected back and forth between mirrors, they repeatedly strike other excited molecules, thereby causing additional emission of photons. Thus the photon intensity within the optical chamber builds by many orders of magnitude. One of the mirrors at the end of this optical chamber is a partial reflector, which allows a portion of the light to escape as single directional beam of great intensity. It is the ability of the laser to deliver very intense light that can be focused to a small spot that gives the device promise for the treatment of vascular obstructions. Lasers can emit light in either a continuous or pulsed mode. The effect of this laser light on tissue varies with the color or wavelength, the intensity, and the mode of delivery. The three commonly used medical lasers are the CO2, Nd:YAG, and argon ion. The CO2 laser, which emits far infrared light, is typically used in the continuous mode to ablate tissue. The laser energy, absorbed by tissue water, penetrates only 50 to 100 μm into the tissue. The far infrared light energy is absorbed by the tissue water, which turns to steam and heats the surrounding organic material. The Nd:YAG laser also operates in a continuous-wave mode. Light from the Nd:YAG laser penetrates more deeply into the tissue and is absorbed largely by protein. As larger volumes of tissue are heated with the same amount of energy, the Nd:YAG laser tends to produce tissue necrosis and coagulation before significant ablation. The argon laser is most strongly absorbed by pigmented material, particularly hemoglobin and myoglobin. As such its depth of penetration and tissue effects vary with the target tissue.7Eichler J Knof J Lenz H. Measurement on the depth of penetration of light 0.35-1.0 hertz in tissue.Radiat Environ Biophys. 1977; 14: 239Crossref PubMed Scopus (95) Google Scholar It is used in the continuous mode and also produces its effect by thermal ablation. Thermal injury can be limited by pulsing the laser energy and several medical lasers now have optional pulsed delivery modes. By pulsing the laser output it is possible to deliver greater energy in short bursts, causing tissue vaporization before thermal diffusion occurs.8Deckelbaum LI Isner JM Donaldson RF et al.Reduction of laser induced pathologic tissue injury using pulsed energy delivery.Am J Cardiol. 1985; 56: 662Abstract Full Text PDF PubMed Scopus (103) Google Scholar, 9Anderson RR Parrish JA. Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation.Science. 1983; 220: 524-527Crossref PubMed Scopus (2747) Google Scholar However, repetitive pulsing of lasers that generate high tissue ablation temperatures (greater than 100° C) can cause significant thermal injury, as heat build-up occurs more rapidly than cooling by thermal diffusion.10Laufer G. Primary and secondary damage to biological tissue induced by laser radiation.Appl Optics. 1983; : 676-678Crossref PubMed Scopus (23) Google Scholar The three commonly used medical lasers have two significant potential limitations for laser angioplasty. First, they all cause some degree of thermal injury. Second, none of these devices can ablate densely calcified tissue. There are two additional current limitations; there are no sufficiently flexible fiberoptics capable of transmitting CO2 laser energy, and the fiberoptics for argon and Nd:YAG lasers tend to melt when intravascular debris accumulates on the catheter tip.11Cothern RM Hayes GB Kramer JR Sacks B Kitrell C Feld MS. A multiple fiber catheter with an optical shield for laser angiosurgery.Lasers Surg Sci. 1986; 1: 1Google Scholar During the past 3 years, we have tested pulsed ultraviolet laser energy, photons delivered in 100 to 200 billionths per second per pulse, as an energy source for laser angioplasty.12Grundfest W Litvack F Morgenstern L et al.Effect of excimer laser irradiation on human atherosclerotic aorta: amelioration of laser-induced thermal damage.IEEE-CLEEO Tech Dig. 1984; : 248-249Google Scholar The laser source that generates short ultraviolet pulses is the xenon chloride excimer laser operating at 309 nm. The protein and lipid in atherosclerotic tissue avidly absorbs this ultraviolet light. The absorption is so intense that the light produced by the excimer laser at 308 nm penetrates only 5 to 10 μm to the tissue. Thus, a very small volume of tissue is vaporized with minimal generation of heat.13Grundfest WS Litvack F Forrester JS et al.Laser ablation of human atherosclerotic plaque without adjacent tissue injury.J Am Coll Cardiol. 1985; 5: 929-933Abstract Full Text PDF PubMed Scopus (260) Google Scholar Incisions made by the excimer laser are microscopically precise. Our research group has recently constructed a flexible fiberoptic bundle consisting of three 300 μm fibers capable of delivering 308 nm excimer energy at energy densities in excess of 100 MJ/mm2 to the tissue.14Grundfest W Litvack IF Goldenberg T et al.Pulsed ultraviolet lasers and the potential for safe laser angioplasty.Am J Surg. 1985; 150: 220-226Abstract Full Text PDF PubMed Scopus (118) Google Scholar Therefore, it is possible to precisely ablate the calcified atheroma with minimal thermal injury. Fig. 7 compares the histologic effects of laser ablation of a segment of human atherosclerotic aorta.The right and center panels show craters created by an argon and Nd:YAG laser, respectively. There is carbonization of the crater margins, coagulation of the crater edges, and vacuole formation deep to the crater. In contrast, the excimer laser (left panel) ablated tissue precisely. Our work has also shown that it is possible to ablate bone and totally obstructed calcified human arteries with excimer laser energy.15Litvack F. Grundfest W Beeder C Forrester JS. Laser angioplasty: status and prospects.Semin Intervent Radiol. 1986; 3: 75-81Crossref Scopus (7) Google Scholar The healing process occurring after laser ablation of vascular endothelium has been studied by many investigators.16Gerrity RG Loop FD Golding LR Ehrhart LA Argenyi ZB. Arterial response to laser operation for removal of atherosclerotic plaques.J Thorac Cardiovasc Surg. 1983; 85: 409-421PubMed Google Scholar, 17Abela CS Crea F Seager JM et al.The healing process in normal canine arteries and in atherosclerotic monkey arteries after transluminal laser irradiation.Am J Cardiol. 1985; 56: 983-988Abstract Full Text PDF PubMed Scopus (40) Google Scholar Acutely and for several days after ablation the craters contain platelet-fibrin thrombi. At 2 weeks the crater surface has reendothelialized, occasionally with incorporation of thrombus. All four lasers have been used to recanalize obstructed vessels in animal models. Abela et al.18Abela GDS Norman SJ Cohen D et al.Laser recanalization of occluded atherosclerotic arteries: an in vivo and in vitro study.Circulation. 1985; 71: 403-411Crossref PubMed Scopus (134) Google Scholar, 19Abela GS Cohen D Feldman RL Geiser EA Norman S Conti LR. Use of laser radiation to recanalize stenosed arteries in a live animal model.Circulation. 1982; 66: 366Google Scholar recanalized atherosclerotic obstructions in rabbits but perforation was a significant problem. In subsequent studies, Sanborn et al.20Sanborn TA Faxon DP Haudenschild CC Ryan JJ. Experimental angioplasty: circumferential distribution of laser thermal energy with a laser probe.J Am Coll Cardiol. 1985; 5: 934-938Abstract Full Text PDF PubMed Scopus (117) Google Scholar placed a metal cap on the waveguide and, with thermally assisted angioplasty, sharply reduced the risk of vessel perforation. Sanborn et al.20Sanborn TA Faxon DP Haudenschild CC Ryan JJ. Experimental angioplasty: circumferential distribution of laser thermal energy with a laser probe.J Am Coll Cardiol. 1985; 5: 934-938Abstract Full Text PDF PubMed Scopus (117) Google Scholar showed that the metal cap radially distributes the heat produced as the metal cap absorbs the laser energy. We have recanalized totally occluded femoral arteries in dogs with the use of excimer laser irradiation. Hard fibrotic obstructions can be ablated with minimal thermal injury. In studies on normal canine aorta in vivo, we have demonstrated that excimer ablation causes minimal adjacent tissue damage, and the temperature of ablation does not exceed 47° C.21Grundfest WS Litvack IF Doyle L et al.Comparison of in vitro and in vivo thermal effects of argon and excimer lasers for laser angioplasty.Circulation. 1986; 74: 813AGoogle Scholar At 1 month, the endothelium is entirely reconstituted with minimal proliferative response. In contrast, ablation of the aorta with argon laser irradiation produced carbonized craters. At 1 month a dense fibrotic reaction was present in the media and adventitia.22Litvack F Doyle L Hickey A et al.Comparison of the acute and chronic response of normal canine aorta to excimer and argon irradiation.Circulation. 1986; 74: 1438AGoogle Scholar Human studies are still too preliminary to draw reasonable conclusions. Initial attempts at laser angioplasty in both peripheral and coronary arteries were not successful. Mechanical perforation, inability to control thermal ablation, and the inadequate channel size led to a high clinical failure rate.23Ginsberg R Wexler L Mitchell RS Profitt D. Percutaneous transluminal laser angioplasty for treatment of peripheral vascular disease: clinical experience with sixteen patients.Radiology. 1985; 156: 619-624PubMed Google Scholar, 24Choy DJ Stertzer SH Myles RK March J Fourneal G. Human coronary laser recanalization.Clin Cardiol. 1984; 7: 377-381PubMed Google Scholar In our own studies with angioscopically guided intraoperative argon laser angioplasty, we were unable to recanalize calcific obstructions. The remaining surface was charred and irregular. The problem of tip destruction and perforation has led to the development of metal-capped,25Sanborn TA Faxon DP Haudenschild CC Ryan TJ. Laser radiation of atherosclerotic lesions: decreased evidence of vessel perforation with a fiberoptic laser heated metallic tip.J Am Coll Cardiol. 1984; 3 (Abstract): 490Google Scholar sapphire-tipped,26Geschwind H, Smith S, Blair J, Mongkolamai D, Kennedy HL. Sapphire contact probe catheters for angioplasty. (Abstract) Sixteenth Annual Symposium of the Texas Heart Institute: International Symposium on Interventional Cardiology. (In press.)Google Scholar or optically shielded27Cothern RM Kittrell C Hayes GB et al.Controlled light delivery for laser angiosurgery.IEEE J Quantum Elect. 1986; 22: 4Crossref Scopus (26) Google Scholar fibers. Cumberland et al.28Cumberland DC Sanborn T Taylor DI Ryan TJ. Percutaneous laser thermal angioplasty: clinical experience in peripheral artery occlusions.J Am Coll Cardiol. 1986; 2: 211AGoogle Scholar have recanalized totally occluded superficial femoral and popliteal arteries in humans with the metal-capped optical fibers. In all cases creation of a new channel by the heater probe is followed by balloon angioplasty. The reported initial success rate, documented by both angiography and clinical status, approaches 80% to 90%.29Cumberland DC Tayler DI Welsh CL et al.Percutaneous laser thermal angioplasty: initial clinical results with a laser probe in total peripheral artery occlusions.Lancet. 1986; 1: 1457-1459Abstract PubMed Scopus (176) Google Scholar Even long-segment, totally occluded superficial femoral arteries have been successfully recanalized by this technique. Perforations have been of minimal clinical significance and acute thrombosis is rare. These preliminary results suggest that thermal recanalization of large vessels may become a valuable adjunct to the treatment of occlusive vascular disease of the superficial femoral artery. Initial experience in transferring this technology to coronary arteries has been less encouraging. Thus far there have been seven cases reported in non-peerreviewed forums.30Cumberland DC Oakley GDG Smith GH et al.Percutaneous laser-assisted coronary angioplasty.Lancet. 1986; 2 (Letter): 214-215Abstract PubMed Scopus (80) Google Scholar, 31Crea F Davies G McKenna W Pashazade M Taylor K Maseri Percutaneous laser recanalization of coronary arteries.Lancet. 1986; 2 (Letter): 214Abstract PubMed Scopus (34) Google Scholar In seven reported attempts, there have been two myocardial infarctions, one intraoperative perforation, and one unsuccessful angioplasty. Although the future of thermal probe angioplasty in small vessels remains to be determined, it is clear that improvements in the device technology are essential. Our trials of the excimer laser in peripheral atherosclerotic disease are pending approval by the Food and Drug Administration. There seems to be little doubt that in the future, many vascular disease problems will be treated by recanalization from within. However, the method of recanalization remains unclear. We now have balloons, mechanical devices,32Simpson JB. Transluminal atherectomy: experimental and clinical results. Sixteenth Annual Symposium of the Texas Heart Institute. International Symposium on Interventional Cardiology (In press).Google Scholar, 33Hansen D Duth D Vracks R Ritchie J. Rotating mechanical angioplasty in atherosclerotic iliac arteries in rabbits.J Am Coll Cardiol. 1986; 7: 213AGoogle Scholar and lasers. The long-term effects of these interventions in humans are entirely unknown. By-products created by intravascular intervention are incompletely studied.34Crewe D Castaneda-Zuniga W Nordstrom L et al.Debris analysis after laser photo recanalization of atherosclerotic plaque.Semin Intervent Radiol. 1986; 3: 53-60Crossref Scopus (6) Google Scholar Remarkably, however, there is little evidence of important distal embolization in the preliminary investigations conducted thus far. Beyond the primary technologies lies the question of the best method of guidance. X-ray, angioscopic, and spectroscopic35Sartori M Henry PD Roberts R. Estimation of arterial wall thickness and detection of atherosclerosis by laser-induced argon fluorescence.J Am Coll Cardiol. 1986; 7: 207AGoogle Scholar systems have all been proposed and tested. Even when atheroma can be successfully ablated in peripheral vessels with good results, as now seems likely, there will be formidable obstacles to small vessel application. The most important problems in the coronary and tibial systems are miniaturization of the devices and creation of a lumen sufficiently large to reduce the risk of thrombosis without causing perforation of the vessel. The key to the introduction of all these technologies will be the development of appropriate catheter delivery systems. These catheters will have to be flexible, atraumatic, low profile, and steerable. As the technology continues to develop, we can reasonably anticipate a major expansion of intravascular treatments in patients with obstructive atherosclerotic disease. However, the ultimate role, if any, of these angioplasty devices will depend on the results of clinical trials, and if successful, will reflect collaborative efforts of vascular and cardiac surgeons, cardiologists, radiologists, and device manufacturers. We acknowledge the contribution of the Division of Cardiovascular Surgery, in particular Drs. Jack Matloff, Carlos Blanche, and Robert Kass. We also acknowledge the generous contributions of the Imperial Grand Sweepstakes, Medallions Fund and Grand Sweepstakes of Cedars-Sinai Medical Center. We would also like to express our appreciation to Dr. Tsvi Goldenberg, of Bell Laboratories, Allentown, Pa., and to Thomas Pacala, Ph.D., and James Laudenslager, Ph.D., of NASA Jet Propulsion Laboratories, Pasadena. Calif.

To visualize intracoronary lesions in patients with different clinical expressions of coronary disease, we performed coronary angioscopy during coronary-artery bypass surgery in 10 patients with unstable angina and 10 patients with stable coronary disease. We examined a total of 32 vessels, using flexible fiberoptic angioscopes. Twenty-two vessels had no acute intimal lesion; three had complex plaques, six had thrombi, and one had both. Coronary angiography correctly identified the absence of complex plaque and thrombus in 22 vessels, but it detected only one of four complex plaques and one of seven thrombi. On angioscopy, none of the 17 arteries in the patients with stable coronary disease had either a complex plaque or thrombus. In the "offending" arteries of the patients with unstable angina, all three patients with accelerated angina had complex plaques and all seven with angina at rest had thrombi. We conclude that angioscopy frequently reveals complex plaques or thrombi not detected by coronary angiography. Our observations suggest that anginal syndromes that are refractory to medical treatment can be caused by unstable pathologic processes in the intima. Ulceration of plaques may increase the frequency and severity of effort angina, and the subsequent development of partially occlusive thrombi may cause unstable rest angina.

In this study, the development of intraoperative angioscopy, the value of the information obtained, and the problems encountered with the procedure are reported. Eight angioscopes, 1.5 to 2.8 mm in diameter, with a line resolution of greater than 0.4 mm at 5 mm, were used. One-hundred ten angioscopic investigations were performed in 46 patients; 24 at peripheral bypass surgery and 22 at coronary artery bypass surgery. These included 68 arteries, 28 new anastomoses, six old grafts, five laser angioplasties, and three in situ vein grafts. The most important finding was that angioscopic data provide information not available from probes or angiography. Angioscopic findings were responsible for a change in surgical procedures in 12 patients (26%) including three anastomotic revisions, three alterations in graft site placement, and two repeat thrombectomies. The most significant technical problems were lack of steerability and insufficient irrigation, which resulted in poor angiographic images. Further technical development is necessary before routine intraoperative angioscopy is practical. Nevertheless, if these problems are resolved, angioscopy will provide unique, high-resolution information which can directly alter surgical therapy.

When life-threatening cardiogenic shock (CI 1.8 1/min/m/sup 2/, elevated right and left-side filling pressures) occurs early (0-48 hrs) after open-heart surgery, routine approaches frequently cannot distinguish between expected etiologies: (1) transient systolic failure of the LV, RV, or both, common early postoperatively (postop); (2) perioperative infarct of the LV or RV; (3) myocardial restriction due to active pericardial bleeding or to accumulated clots and fluid; (4) diminished LV reserve from aneurysmectomy; and (5) residual valvular regurgitation. Distinction is critical, because (1), (2), and (4) will be treated by optimizing preload and afterload; (3) with urgent (if active bleeding) or semi-urgent surgery; and (5) with repeat valvular surgery. In 22 pts with unexpected early postop cardiogenic shock, Tc-99m-RBC equilibrium radionuclide ventriculography revealed: global LV (3 pts) or RV (3 pts) dysfunction, new segmental LV dysfunction (2 pts), active bleeding (5 pts) and/or accumulated pericardial fluid ( 8 pts) with hyperdynamic LV and RV, and a small hyperdynamic LV without effusion (1 pt), providing a specific etiologic diagnosis in all cases. In the Cardiac Surgical ICU, therapeutic decisions frequently await and depend on the results of equilibrium radionuclide ventriculography, now routinely performed in postop pts with unexpected cardiogenic shock.

Persistent bleeding into the pericardial space in the early hours after cardiac operation not uncommonly results in cardiac tamponade. Single chamber tamponade also might be expected, since in this setting the pericardium frequently contains firm blood clots localized to the area of active bleeding. However, this complication has received very little attention in the surgical literature. We are therefore providing documentation that isolated right atrial tamponade can occur as a complication of cardiac operation and that there exists a potential for misdiagnosis and hence incorrect treatment of this condition. Right atrial tamponade may be recognized by a combination of low cardiac output, low blood pressure, prominent neck veins, right atrial pressure in excess of pulmonary capillary wedge pressure and right ventricular end-diastolic pressure, and a poor response to plasma volume expansion. Findings on chest roentgenogram and gated wall motion scintigraphy may be highly suggestive. This review should serve to increase awareness of this complication and to provide some helpful diagnostic clues.