Several techniques exist for percutaneous extraction of chronic pacemaker leads. To establish the efficacy of the Dotter retriever and pigtail catheter, we reviewed the removal of 59 endocardial pacemaker leads in 42 patients (mean age 71 years). The mean duration of lead implantation was 44 months (range 1-169 months). Thirty-two leads were withdrawn with simple traction alone, and five leads were abandoned when traction failed. The remaining 22 leads were manipulated with a Dotter retriever or pigtail catheter, or both. Twelve leads were dislodged from the endocardium with simple traction (10) or with traction transmitted through an entwining pigtail catheter (2), but they could not be fully withdrawn. Eleven of these leads (92%) were then successfully extracted with the Dotter retriever. Seven of the remaining 10 leads were successfully dislodged and removed by the Dotter retriever. Overall, 9 of 12 leads (75%) that could not be dislodged from the endocardium with simple traction were removed with a Dotter retriever or pigtail catheter, or both. Three patients in whom no catheter method worked required thoracotomy for removal of infected leads. No complications resulted from use of the Dotter retriever or pigtail catheter. We conclude that the Dotter retriever and pigtail catheter have moderate efficacy for dislodging chronic endocardial leads. Once mobilized, however, the leads can be withdrawn with great success with the Dotter retriever. Newer technology should not result in the abandonment of this proven technique.

Adolescent↗

PubMed1992

Results of directional atherectomy of primary atheromatous and restenosis lesions in coronary arteries and saphenous vein grafts.

Directional coronary atherectomy (DCA) was performed in 158 patients over a 2-year period at the Mayo Clinic. Primary atheromatous lesions were treated in 92 patients (group 1) and restenosis lesions were treated in 66 (group 2). Technical success (recovery of tissue and greater than or equal to 40% luminal enlargement with a residual stenosis of less than 50%) was achieved in 152 lesions (92%); clinical success (technical success and no in-hospital death, Q-wave myocardial infarction or coronary bypass surgery) was achieved in 143 patients (91%). Adjunctive balloon angioplasty was used in 41 patients. DCA was successful less often in group 1 than in group 2 (86 vs 97%; p = 0.038). A major complication occurred in 7% of patients; in-hospital death, Q-wave myocardial infarction and emergency coronary bypass surgery occurred in 3, 1 and 4% of patients, respectively. Major complications were more frequent in group 1 than in group 2 (10 vs 1; p = 0.02). During a follow-up period of 14 +/- 8 months, no difference between the groups was found in the incidence of late death (4%), Q-wave myocardial infarction (1%), recurrent severe angina (29%), bypass surgery (15%) or repeat interventional procedure of the same vascular segment (24%). Vein graft and restenosis lesions tended to have greater success and fewer complications. Angiographic restenosis (increase of greater than or equal to 30% in stenosis severity by visual assessment) occurred in 62% of patients and 58% of lesions with successful DCA, and was similar in the 2 groups; a tendency toward higher restenosis rates was seen in patients with vein graft DCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

High-tech medicine in low-tech countries.

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Developing Countries↗

PubMed1992

Effect of external beam irradiation on neointimal hyperplasia after experimental coronary artery injury.

Human coronary artery restenosis after percutaneous revascularization is a response to mechanical injury. Smooth muscle cell proliferation is a major component of restenosis, resulting in obstructive neointimal hyperplasia. Because ionizing radiation inhibits cellular proliferation, this study tested in a porcine coronary injury model the hypothesis that the hyperplastic response to coronary artery injury would be attenuated by X-irradiation. Deep arterial injury was produced in 37 porcine left anterior descending coronary artery segments with overexpanded, percutaneously delivered tantalum wire coils. Three groups of pigs were irradiated with 300-kV X-rays after coil injury: Group I (n = 10), 400 cGy at 1 day; Group II (n = 10), 400 cGy at 1 day and 400 cGy at 4 days and Group III (n = 9), 800 cGy at 1 day. Eight pigs in the control group underwent identical injury but received no radiation. Treatment efficacy was histologically assessed by measuring neointimal thickness and percent area stenosis. Mean neointimal thickness in all irradiated groups was significantly higher than in the control groups and thickness was proportional to X-ray dose. X-irradiation delivered at these doses and times did not inhibit proliferative neointima. Rather, it accentuated the neointimal response to acute arterial injury and may have potentiated that injury.

Angioplasty, Balloon, Coronary↗

PubMed1992

Restenosis and the proportional neointimal response to coronary artery injury: results in a porcine model.

Restenosis is a reparative response to arterial injury occurring with percutaneous coronary revascularization. However, the quantitative characteristics of the relation between vessel injury and the magnitude of restenotic response remain unknown. This study was thus performed to determine the relation between severity of vessel wall injury and the thickness of resulting neointimal proliferation in a porcine model of coronary restenosis. Twenty-six porcine coronary artery segments in 24 pigs were subjected to deep arterial injury with use of overexpanded, percutaneously delivered tantalum wire coils. The vessels were studied microscopically 4 weeks after coil implantation to measure the relation between the extent of injury and the resulting neointimal thickness. For each wire site, a histopathologic score proportional to injury depth and the neointimal thicknesses at that site were determined. Mean injury scores were compared with both mean neointimal thickness and planimetry-derived area percent lumen stenosis. The severity of vessel injury strongly correlated with neointimal thickness and percent diameter stenosis (p less than 0.001). Neointimal proliferation resulting from a given wire was related to injury severity in adjacent wires, suggesting an interaction among effects at injured sites. If the results in this model apply to human coronary arteries, restenosis may depend on the degree of vessel injury sustained during angioplasty.

Angioplasty, Balloon, Coronary↗

PubMed1992

Percutaneous polymeric stents in porcine coronary arteries. Initial experience with polyethylene terephthalate stents.

BACKGROUND: To test the feasibility of percutaneous deployment of intracoronary polymeric stents, a prototype polyethylene terephthalate (PET) stent and a catheter-based delivery system were developed. METHODS AND RESULTS: Polymeric stents were deployed in the coronary arteries of 11 Yucatan swine: six stents were placed in the left anterior descending coronary artery, four stents were placed in the circumflex artery, and one stent was placed in the right coronary artery. Stent deployment was achieved by withdrawal of an outer delivery sheath, thus allowing the PET stent to self-expand to a preformed configuration. Two animals died during surgery, one during stent placement and the other several hours after implantation due to intracoronary thrombus formation. Two animals were electively sacrificed within 24 hours of stent implant to examine the adequacy of stent deployment within the coronary vessel. The remaining seven animals survived until the termination of the study 4-6 weeks later. Light microscopic examination of the stented vessels showed an extensive neointimal proliferative response with vessel occlusion in all animals who survived initial stent placement. There were two distinct types of histological responses to the PET stent--a chronic foreign body inflammatory response around the stent tines and a neointimal proliferative response in the center of the occluded vessel lumen. The histological response seen in the central area of the vessel was morphologically similar to that seen in patients with restenosis after successful percutaneous transluminal coronary angioplasty, whereas the morphological response seen at the periphery of the stent tine was similar to that exhibited by a chronic foreign body reaction and was not typical of that seen in a restenosis lesion. A ventricular aneurysm also developed in the area of myocardium that was previously supplied by the occluded vessel. CONCLUSIONS: This study demonstrates that percutaneous deployment of polymeric stents in the coronary arteries is technically feasible. The use of PET polymer was associated with an intense proliferative neointimal response that resulted in complete vessel occlusion. Histological examination of the stented segments of the vessel revealed no evidence that dissection of the vessel wall had occurred at the time of initial stent deployment. Although the PET polymer was of similar quality to that used in the manufacture of balloon angioplasty catheters, a toxic chemical or contaminant effect cannot be completely excluded as the stimulus to intimal proliferation. This finding may have relevance to the selection of materials for use as intravascular devices.

Animals↗

PubMed1991

Consequences of restenosis after coronary angioplasty.

The consequences of restenosis after angioplasty were evaluated in 466 patients who had coronary angiography 3 to 12 months after successful coronary angioplasty and were followed long term. The 236 subjects with restenosis resembled the 230 without restenosis with respect to age, sex, presence of multivessel disease, mean ejection fraction, prior myocardial infarction, prior coronary artery bypass grafting, and completeness of revascularization. The 5-year relative risk of revascularization for patients with restenosis markedly exceeded that for patients without restenosis. The relative risk of repeat angioplasty in the former group was 4.26 times that in the latter group (95% confidence interval, 2.80 to 6.51), and the risk of coronary artery bypass grafting in patients with restenosis was 3.68 (95% confidence interval, 2.16 to 6.28). There was no difference between the 2 groups in the relative risk of myocardial infarction or death. When the completeness of revascularization was considered, patients with incomplete revascularization and restenosis had the worst outcomes, with 50% needing coronary artery bypass grafting within 5 years. Early restenosis markedly increases the probability of revascularization, but it has little effect on infarction or mortality. Even when early restenosis is absent, further revascularization procedures are still frequent. A solution to the problem of restenosis might reduce by half the need for revascularization during the subsequent 5 years.

Angioplasty, Balloon, Coronary↗

PubMed1991

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.

Angioplasty, Balloon↗

PubMed1991

A randomized comparison of the nephrotoxicity of iopamidol and diatrizoate in high risk patients undergoing cardiac angiography.

Three hundred seven high risk patients with renal impairment (serum creatinine greater than or equal to 1.5 mg/dl) were randomized in a double-blind manner to either iopamidol (a nonionic, low osmolar radiocontrast agent) or diatrizoate (a conventional radiocontrast agent) at cardiac angiography with subsequent follow-up study of renal function. Baseline clinical and angiographic variables were similar in the iopamidol (n = 155) and diatrizoate (n = 152) groups. Change in renal function after angiography was less pronounced with iopamidol compared with diatrizoate as measured by mean ( +/- SD) increase in 24 h serum creatinine (0.11 +/- 0.2 versus 0.22 +/- 0.26 mg/dl, p less than 0.001), mean maximal increase in serum creatinine (0.2 +/- 0.44 versus 0.38 +/- 0.73 mg/dl, p less than 0.0001) and percent of patients with a maximal increase in serum creatinine greater than 0.5 mg/dl (8% versus 19%, p less than 0.01). Such differences could not be documented in diabetic patients using insulin. There was no significant difference between agents in the number of patients developing clinically severe acute renal dysfunction. It is concluded that iopamidol is less nephrotoxic than diatrizoate in high risk patients at cardiac angiography. However, the difference in nephrotoxicity is small, of no major clinical significance in the majority of high risk patients and could not be documented in insulin-using diabetic patients. Iopamidol may be the preferred agent in certain patients with advanced renal impairment, but further study is warranted.

Acute Kidney Injury↗

PubMed1991

Differential histopathology of primary atherosclerotic and restenotic lesions in coronary arteries and saphenous vein bypass grafts: analysis of tissue obtained from 73 patients by directional atherectomy.

Vascular tissue obtained using a directional percutaneous atherectomy device was examined microscopically. Tissue was obtained from coronary arteries without prior instrumentation (primary lesions, n = 31), aortocoronary saphenous vein bypass grafts with primary lesions (n = 8), coronary arteries with lesions developing after prior balloon angioplasty or mechanical atherectomy (restenotic lesions, n = 30) and vein bypass grafts with restenotic lesions (n = 4). Primary lesions were characterized by dense intimal fibrosis with necrotic debris (83% of intimal tissue) and foam cells typical of atherosclerosis. These lesions frequently contained cholesterol crystals (45% of coronary arteries, 50% of vein grafts) and calcium deposits (65% of coronary arteries, 38% of vein grafts). Restenotic lesions were characterized by an increased proportion of loose fibroproliferative tissue (45% of coronary artery intima, 35% of vein graft intima). Immunohistochemical stains confirmed this proliferative tissue to be primarily smooth muscle cells. Thrombus was rarely observed. Comparison of resected tissues indicated that dense fibrosis and necrosis are significantly more common in primary than in restenotic lesions (83% versus 56% of intimal tissue, p = 0.0005), whereas smooth muscle cell hyperplasia is more common in restenotic than in primary lesions (44% versus 17% of intimal tissue, p less than 0.0005). Partial-thickness resection of medial tissue or full-thickness resection of media with associated adventitial tissue occurred in 27 (56%) of 39 primary atheromatous lesions and 16 (47%) of 34 restenotic lesions; subintimal tissue obtained from primary lesions appeared identical to that obtained from restenotic lesions. These data indicate that the histopathologic characteristics of the neointimal layer of restenotic lesions differ from those of the intimal layer of primary atherosclerotic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Constriction, Pathologic↗

PubMed1991

Antitachycardia pacemaker treatment of postoperative arrhythmias in pediatric patients.

An automatic antitachycardia pulse generator (Intertach 262-12) was implanted in each of six pediatric patients (mean age, 10 years) with drug-resistant and persistent postoperative supraventricular arrhythmias. Four had bradycardia-tachycardia syndrome, two after a Mustard procedure for transposition of the great arteries, one after a Senning procedure for the same anomaly, and one after a Fontan procedure for univentricular heart with transposition of the great arteries. Of the two remaining patients, one had atrial flutter after a modified Fontan procedure for univentricular heart and one had intra-atrial reentry tachycardia after a modified Fontan procedure for double-outlet right ventricle with pulmonary stenosis. During a mean follow-up interval of 31 months after implantation, pacemakers were activated on multiple occasions and functioned appropriately in all six patients. Complications necessitated six invasive interventions in three patients: erosion or infection of the system, adaptor fracture, and connector block fracture on one occasion each and lead dislodgment on three occasions. Four of the six patients continued to take drugs at the end of this study; however, all patients had their drug therapy reduced and one was taking digoxin only. The number of hospital admissions decreased after implantation. Despite a number of technical challenges, this newer multiprogrammable antitachycardia pacemaker appears to be a valuable addition to the treatment of refractory postoperative supraventricular tachyarrhythmias in pediatric patients.

Adolescent↗

PubMed1991

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.

Angioplasty, Balloon, Coronary↗

PubMed1991

Ventricular pacing from the atrial channel of a DDD pacemaker.

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Aged↗

PubMed1990

[Coronary restenosis 6 months following transluminal atherectomy].

UNLABELLED: Directional coronary atherectomy was developed to decrease the incidence of restenosis. Among the first 61 patients treated with directional atherectomy at Mayo Clinic, 50 have been considered a success. Half of the patients had had one or more previous PTCA performed on the target lesion. Patients were followed during 6 months. Coronary angiogram was performed 6 months after atherectomy or earlier if ischemia appeared. Restenosis was defined as a greater than or equal to 50% luminal narrowing or loss of greater than or equal to 50% of the initial gain. Ischemia was documented in 23 patients. Control angiogram demonstrated restenosis in 24 patients (48%). Among those 24 patients, 18 had ischemia documented during stress test or at rest, and underwent a second procedure (second atherectomy in 4, PTCA in 8 and bypass surgery in 6 patients). Neither previous procedures nor the type of vessel significantly influenced restenosis rates. CONCLUSIONS: coronary restenosis was not less frequent after directional atherectomy, than after conventional balloon angioplasty. Previous procedures or type of vessel did not influence restenosis incidence.

Adult↗