Temperature-controlled high frequency ablation for creation of transmyocardial channels: in vivo validation of a novel method

OBJECTIVE

We investigated the feasibility and short-term effects of a novel procedure to create intramyocardial channels by means of high frequency (HF) ablation in a rabbit in vivo model.

METHODS

A flexible catheter ending in a cylindrical electrode (diameter 0.7 mm) with a sharpened tip was used for HF energy application following transmyocardial insertion. Power-controlled or energy-controlled energy applications were performed in 16 anesthetized rabbits after thoracotomy with a follow-up for 3 h. Assessment of myocardial channels and the necrotic zone was performed by morphometric quantification in serial sections. The ferret diameter was used to compare channel dimensions and the extent of necrosis.

RESULTS

Thirty-nine power-controlled and 54 temperature-controlled HF applications were performed. The shape of identified channels was round in 71% and 69% had a lumen patency of > or =2/3 of the channel. Ferret diameter of the channels was 414 +/- 180 microm and of the necrotic zone 3,558 +/- 1,200 microm. In temperature-controlled applications, channel dimensions were strongly influenced by the maximum tissue temperature and the duration of energy delivery (T(max): p = 0.0006; duration: p = 0. 003). Channel and necrosis dimensions correlated better with biometric parameters in temperature-controlled compared with power-controlled applications.

CONCLUSION

Mechanically created transmyocardial channels can be stabilized by HF heating of the surrounding tissue. A high percentage of these channels remain patent. The channel dimensions are closely correlated with maximum temperature and duration of energy delivery in a temperature-controlled application mode.

A randomized comparison of balloon angioplasty versus rotational atherectomy in complex coronary lesions (COBRA study)

AIMS

Rotablation is a widely used technique for the treatment of complex coronary artery lesions but is so far only poorly supported by controlled studies. The Comparison of Balloon-Angioplasty versus Rotational Atherectomy study (COBRA) is a multicentre, prospective, randomized trial to compare short- and long-term effects of percutaneous transluminal coronary angioplasty (PTCA) and rotablation in patients with angiographically pre-defined complex coronary artery lesions.

METHODS AND RESULTS

At seven clinical sites 502 patients with pre-defined complex coronary artery lesions were assigned to either PTCA (n=250) or rotablation (n=252). Primary end-points were procedural success, 6-month restenosis rates in the treated segments, and major cardiac events during follow-up. Procedural success was achieved in 78% (PTCA), and 85% (rotablation) (P=0.038) of cases. Crossover from PTCA to rotablation was 4% and 10% vice versa (P=0.019). There was no difference between PTCA and rotablation with respect to procedure-related complications such as Q wave infarctions (2.4% each), emergency bypass surgery (1.2% versus 2.4%), and death (1.6% versus 0.4%). However, more stents were required after PTCA (14.9% versus 6.4%, P<0.002), predominantly for bailout or unsatisfactory results. Including bail-out stents as an end-point, the procedural success rates were 73% for angioplasty and 84% for rotablation (P=0.006). At 6 months, symptomatic outcome, target vessel reinterventions and restenosis rates (PTCA 51% versus rotablation 49%, P=0.33) were not different.

CONCLUSION

Complex coronary artery lesions can be treated with a high level of success and low complication rates either by PTCA with adjunctive stenting or rotablation. The long-term clinical and angiographic outcome is comparable.

Impact of routine angiographic follow-up after angioplasty

BACKGROUND

There is an ongoing controversy as to whether repeat coronary angiography should be routinely performed after successful percutaneous transluminal coronary angioplasty (PTCA).

METHODS

We examined the 10-year outcome in 400 patients who had or had not undergone an angiographic control 6 months after successful PTCA and a subsequent event-free 6-month period. Our comparison was based on data gathered by questionnaire and telephone interview in 315 patients with (group A) and 85 patients without (group B) a routine 6-month angiographic control. Multivariate analysis (Cox model) was performed to identify predictors of adverse events.

RESULTS

During the 10-year follow-up period, 22 (7%) of the 315 patients in group A died, compared with 16 (19%) patients in group B (P= .003). In groups A and B, respectively, acute myocardial infarction occurred in 28 (9%) and 10 (12%) patients (not significant [NS]); coronary artery bypass grafting (CABG) was performed in 42 (13%) and 14 (16%) patients (NS); repeat PTCA was performed in 89 (28%) and 11 (13%) patients (P= .012); and serious adverse events (death, myocardial infarction, CABG) occurred in 76 (24%) and 32 (38%) patients (P= .02). Absence of a 6-month angiographic follow-up was identified as an independent predictor of death associated with a 2.7 times higher mortality rate during the 10-year follow-up period. Previous myocardial infarction increased the risk of death 2.5 times. Any increase of residual diameter stenosis by 10% was combined with a 1.4 times higher mortality rate. The chance of bypass surgery was higher in patients with multivessel disease (2.9 times), in patients with unstable angina (2.1 times), and in case of an increase of residual diameter stenosis by 10% (1.3 times). No predictor for the risk of myocardial infarction was found. Angiographic follow-up increased the likelihood of PTCA 2.5 times.

CONCLUSIONS

A routinely performed angiographic control 6 months after successful PTCA is associated with a significantly higher rate of repeat PTCA but, most important, is correlated with a significantly lower mortality rate during the 10-year follow-up period.

[Dynamic 31-phosphorus magnetic resonance spectroscopy of the m. quadriceps: therapy-induced changes in arterial occlusive disease]

PURPOSE

The present investigation aimed at examining changes in muscle metabolism caused by treatment of arterial occlusive disease, using dynamic 31-phosphorus methods.

METHOD

32 patients with arterial occlusive disease were examined in a 1.5 T apparatus with a 6 cm surface coil before and after treatment. The metabolic changes in the quadriceps muscles were visualised during a 36 s phosphorus spectrum during rest, exercise (isometric and isotonic) and during a period of recovery.

RESULTS

Vascular therapy resulted in a significant increase in the duration of both types of exercise during dynamic phosphorus spectroscopy (isometric exercise: 282 s against 199 s: p = 0.002, isotonic exercise: 575 s against 222 s; p = 5 x 10(-6). After treatment, exercise-induced changes in pH (7.00 against 6.94; p = 0.004 and 7.00 against 6.93; p = 0.02) and the ratio Pi/PCr (0.34 against 0.44; p = 0.002 and 0.36 against 0.50; p = 0.009) were significantly smaller than before therapy, using a similar amount of exercise. Recovery time of Pi/PCr (45 s against 82 s; P = 10(-5) and 42 s against 57 s; p = 0.01) and pH value (154 s against 181 s; p = 0.14 and 173 s against 214 s; p = 0.22) showed significant reduction after treatment.

CONCLUSIONS

Dynamic 31-phosphorus magnetic resonance spectroscopy indicates increased mitochondrial oxidative capacity in the quadriceps muscles as evidence for increased oxygen supply to muscle tissue following vascular therapy.

Comparison of QCA systems

AIMS

Excellent agreement between different 'second generation' systems for quantitative coronary arteriography (QCA) has been found in in vitro measurements. To verify the quality and stability of QCA when used in clinical practice, three QCA systems (AWOS, Cardio, and CMS) were used in a representative set of coronary artery lesions.

METHODS AND RESULTS

This set consisted of angiographic stenosis images of 57 patients which varied in stenosis severity and morphology. The process of image acquisition, calibration, and measurement was strictly standardized to eliminate procedural sources of error. Three observers performed QCA five times in each lesion with each QCA system. Interobserver variability was low (Dnorm 0.01-0.05 mm, Dmin 0.01-0.02 mm, %stenosis 0.3-0.7%). Values of system precision were excellent (Dnorm 0.11-0.13 mm, Dmin 0.04-0.06 mm, %stenosis 2.1-2.6%). Comparison of measurements between three QCA systems revealed good agreement (range of mean differences for Dnorm 0.03-0.12 mm, Dmin 0.04-0.11 mm, and %stenosis 0.5-3.6%) and high correlation (corr 0.902-0.977). There was a tendency to measure smaller values for Dmin and consequently to identify more severe stenoses with the AWOS system than with the Cardio and CMS systems. All QCA results were compared to measurements done with the Brown Dodge method to reveal failure of the QCA measurements. These results showed excellent agreement without any systematic deviation (mean differences for Dnorm 0.01-0.08 mm, Dmin 0.02-0.06 mm, and %stenosis 1.3-1.8%). None of the differences were statistically significant.

CONCLUSION

We therefore conclude that using the defined version of the AWOS, Cardio, and CMS systems, there is no difference in precision or accuracy when used for QCA of coronary artery lesions.

[Effect of qualitative stenosis characteristics on the quality of measurements of various QCA systems]

Reproducibility and accuracy of in vitro measurements are very high using recently developed QCA systems. We analyzed the impact of lesion characteristics ad the image quality on the quality of measurements under clinical conditions. For the study we selected 57 coronary artery lesions which had a clinically relevant distribution for stenosis severity, lesion characteristics, and image quality. Every effort was made to eliminate procedural sources of error. Three investigators measured each lesion five times with each of three QCA systems (AWOS, Cardio and CMS). Only the measurements of the minimal stenosis diameter were analyzed. The precision of all the measurements was high with the AWOS (0.04 mm), the Cardio (0.05 mm), and the CMS systems (0.06 mm). Variability of measurements increased for the following criteria: Ambrose-III morphology (CMS 0.082 mm), surface irregularities (Cardio 0.069 mm, CMS 0.073 mm), TIMI I (Cardio 0.084 mm, CMS 0.0121 mm), and moderate image quality (CMS 0.07 mm). There were no differences in the precision of the measurements in the other groups of lesion characteristics. There were no relevant differences in any of the measurements between the systems (AWOS-Cardio -0.07 mm, AWOS-CMS-0.11 mm, Cardio-CMS-0.04 mm). Smaller diameters were measured with the AWOS system than with the CMS and the Cardio systems when the lesion was calcified (AWOS-Cardio-0.109 mm, AWOS-CMS-0.161 mm). This was only a trend, however, and did not reach statistical significance, which was also true for the other differences found between the systems according to various lesion characteristics. In summary, we found that the measurement quality of the QCA systems used in this study is not altered by the underlying lesion characteristics or the image quality.

[Three-dimensional computer reconstruction of the pelvic and hip area in the preoperative planning of orthopedic interventions and surgical simulation]

RESEARCH QUESTION

Osteotomies are elective operations which require exact pre-operative planing. Computer assisted three-dimensional planning of orthopedic procedures requires a three-dimensional reconstruction of the region of interest. To be applicable, such a three-dimensional reconstruction must be an accurate mathematical description of the region of interest, and not only a 3-D-image. The purpose of this study was to create such an accurate 3-D reconstruction.

METHODS

We describe a method to create an exact reconstruction from CT-data, from the data acquisition, contour determination by an algorithm, triangulation of the resulting data and reconstruction of the region of interest.

CONCLUSION

The described method is a useful tool to obtain exact individual three-dimensional reconstructions of any skeletal region of interest. This makes pre-operative planning and simulation of the results of orthopedic procedures at the computer possible.

[Automatic report documentation in cardiology using a speech recognition system]

Computer systems that can convert spoken text into written text have recently become available. In one such system, the phonetics of spoken words are compared with those of 32 000 stored words, with a statistical program helping to choose the word with the highest probability of being correct. We evaluated the practicability of the IBM Voice Type system for writing medical reports using a cardiologic vocabulary. A total of 200 medical documents were generated with a mean of 301 +/- 52 words. In the mean, 12 +/- 5 words were falsely recognized in each document, resulting in a rate of correct recognition of 95.1 +/- 2.5%. It is possible to correct a falsely recognized word by choosing an alternative word from a provided list, which worked in our case in 51% (6.1 +/- 2.8 words in each document). Correction of falsely recognized words had to be done by manual input 49% of the time (5.9 +/- 2.9 words in each document). The mean time demand for word correction amounted to 57 +/- 15 s for each document, whereas correction by manual input needed more time (37 +/- 14 s) than choosing from a list of alternative words (20 +/- 4s). A requirement for use of the Voice Type system is a reduced speech rate. Dictation of our documents took on average 260 s when done with a normal speech rate, and 400 s when done at a reduced speech rate. In conclusion, automatic writing of cardiologic reports can be done easily and with a low failure rate using the IBM Voice Type system with a cardiologic vocabulary. It takes about 3 min longer to create a medical text 1 1/2 pages long which is free of mistakes by using the Voice Type system than to simply dictate the text. Time can be saved by eliminating the need to check a preliminary report. The major advantage of automated reporting is that the written report is immediately available. For each discipline, specific vocabularies should be validated.

Angiographic follow-up results of a randomized study on angioplasty versus bypass surgery (GABI trial). GABI Study Group

Although several randomized trials have been performed to compare the outcomes of percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass surgery (CABG) in patients with multivessel disease, there is little data available on angiographic follow-up results. The present substudy of the German angioplasty versus bypass surgery investigation (GABI Trial) compares the angiographic revascularization status in these two cases 6 months after treatment. Follow-up angiograms were available in 102 CABG patients and 117 PTCA patients. Although the protocol excluded patients with total occlusion, on follow-up 6 months after treatment we found total occlusion of 94 native arteries (36.9%) in the CABG group and of six arteries (2.5%) in the PTCA group (P < 0.001). The rate of occluded native vessels did not correlate significantly with the severity of the lesion before bypass surgery. In the CABG group 31 bypass grafts (12.2%) were found to be occluded at the 6 month follow-up examination (29/225 vein grafts [12.9%]; 2/30 mammary artery grafts [6.7%]). The main pathway, defined as the nutrient vessel (native vessel or bypass graft) providing the least resistance to blood flow, was narrowed by a lesion with a diameter stenosis of 70-100% for 36 target lesions (14.1%) in the CABG group and 39 target lesions (16.2%) in the PTCA group (P, ns). However, the prevalence of moderately severe lesions with a 50-69% diameter reduction of the main pathway was significantly greater in the PTCA group (44 lesions, 18.3%) than in the CABG group (19 lesions, 7.5%, P < 0.01). Thus, 6 months after randomized allocation to PTCA or CABG, we found comparable rates of high-grade lesions in the main pathways of both treatment groups. Whereas moderately severe lesions of the main pathway were predominantly seen in the PTCA group, there was marked disease progression to total occlusion in the native circulation after bypass grafting.

Differential expression of collagen types I, II, III, and X in human osteophytes

BACKGROUND

Osteophytes are neoplastic cartilaginous and osseous protrusions growing at the margins of osteoarthritic joints. Their formation involves complex patterns of cellular proliferation, differentiation, as well as matrix synthesis and turnover that are poorly understood.

EXPERIMENTAL DESIGN

Here we report on an experimental approach using in situ hybridization and immunohistology to elucidate pathways of chrondrocyte differentiation in human osteophytes. Ab and cDNA probes for collagen types were used as specific parameters for chondrocyte phenotypes.

RESULTS

In early precartilaginous mesenchymal tissue, cytoplasmic mRNA for alpha 1(I) and alpha 1(III) collagen genes (Col1A1 and Col3A1) were found by in situ hybridization, correlating with the distribution of type I and III collagen as revealed by Ab staining. Strong expression of type II collagen both at mRNA and protein levels was the hallmark of chondrogenic differentiation in the cartilaginous zone of osteophytes. Type II collagen expression increased in all cartilaginous and fibrocartilaginous areas with growth and maturation of osteophytes. The signal intensity obtained after in situ hybridization with a COL2A1 probe was high and corresponded to that obtained in fetal cartilage, whereas normal adult articular cartilage usually did not show measurable type II collagen expression. In fibrocartilaginous areas, the most abundant, but heterogeneous tissue type seen in osteophytes, type II and III collagen mRNA expression overlapped considerably. Type III collagen was scattered, both pericellularly and interterritorially, over the whole osteophyte, excluding bone and chondrocytic cells of the deep zone. The strongest type I collagen expression was seen in bone and in the superficial fibrous layer. In areas of endochondral ossification, large chondrocytes were found expressing type X collagen, a specific marker for hypertrophic chondrocytes.

CONCLUSIONS

These results show that discrete stages of cartilage differentiation can be precisely followed in osteophytes using collagen type-specific cDNA probes and Ab as markers. In addition, a fibrocartilaginous chondrocyte phenotype was identified that expresses type II and III, but not type I collagen.

High-frequency rotational ablation following failed percutaneous transluminal coronary angioplasty

Percutaneous transluminal coronary angioplasty (PTCA) failed in 29 of 1,150 patients (2.5%) after successful passage of the guide wire. The reasons for failure were inability to pass the lesion with a balloon in 28 patients and inability to dilate the lesion in 1 patient. In these patients (15 stenoses and 14 chronic occlusions) rotational ablation was performed. We were able to pass the burr through the lesion in all of them, resulting in a reduction of diameter stenosis from 87 +/- 15 to 51 +/- 18%. Rotational ablation alone was initially successful (stenoses reduction > 20% and residual stenoses < 50%) in 15 of 29 (52%) patients. Additional PTCA was performed in 21 of 29 (72%) patients, in 8 to optimize the initially successful result and in 13 because the outcome was unsatisfactory. After dilatation the diameter stenosis was reduced to 41 +/- 14% immediately after the procedure and to 36 +/- 13% at 24 hr control. Overall success was achieved in 21 of 29 (72%) patients immediately after the procedure and in 26 of 29 (90%) patients at 24 hr control. No acute major complications occurred. We conclude that rotational ablation can be used as a safe and effective alternative when PTCA is not successful.

High frequency rotational ablation: an alternative in treating coronary artery stenoses and occlusions

OBJECTIVE

To prove the safety and effectiveness of high frequency rotational ablation of coronary artery stenoses and occlusion in humans.

SUBJECTS

106 patients with symptoms (91 men, 15 women) who had 67 significant stenoses, mainly types B and C, and 46-chronic occlusions.

MAIN OUTCOME MEASURES

Mean change in diameter stenosis after rotational angioplasty alone and in combination with percutaneous transluminal coronary angioplasty immediately after treatment and 24 hours and six months later; restenosis rates at six months; complication of treatment.

RESULTS

Rotational ablation could not be used in five stenoses and 16 chronic occlusions because of inability to reach or cross the lesion with the Rotablator guide wire. In four cases rotational ablation failed. Initial angiographic and clinical success by rotational ablation was achieved in 40 of the 67 stenoses (60%) and in 18 of the 46 chronic occlusions (39%). Additional balloon angioplasty was performed in 45 patients, increasing the success rates to 79% and 54%, respectively. In the 62 stenoses treated by rotational ablation the angiographic diameter stenoses were reduced from 76% (SD 14%) to 32% (14%) after Rotablator treatment alone and from 75% (11%) to 33% (17%) with additional balloon angioplasty. In the 30 chronic occlusions treated by rotational ablation the angiographic diameter stenoses were reduced to 38% (18%). At six months angiographic restenosis was evident in nine of the 25 (36%) stenoses treated with rotational ablation alone, in seven of the 22 (32%) stenoses treated with rotational and balloon angioplasty, and in 14 of the 24 (58%) chronic occlusions. There were no procedural deaths and two patients (2%) underwent emergency coronary artery bypass grafting. Although no transmural infarction occurred, there were five (6%) non-Q wave infarctions (two embolic side branch occlusions, two subacute occlusions, and one acute occlusion). Clinically insignificant slight increases in creatine kinase activity were seen in five patients (6%). Severe coronary artery spasm unresponsive to medical treatment was provoked in seven cases (8%).

CONCLUSIONS

High frequency rotational ablation is a safe and effective method for treating type B and C coronary artery lesions with results comparable to percutaneous transluminal coronary balloon angioplasty. The combined use of rotational ablation and balloon angioplasty is feasible and is necessary in about half of all procedures, in most cases because the lumen created by the biggest burr is too small.

Alterations of collagen mRNA expression during retinoic acid induced chondrocyte modulation: absence of untranslated alpha 1(I) mRNA in hyaline chondrocytes

Retinoic acid (RA) has been shown to rapidly modulate the collagen expression pattern of chondrocytes in vitro at doses of 1-10 microM. Embryonic chicken sternal chondrocytes stop synthesizing the cartilage-specific type II collagen within 2-4 days of RA treatment and turn on the synthesis of types I and III collagen and fibronectin. While suppression of type II collagen synthesis and onset of type III collagen and fibronectin synthesis have been shown to be regulated at the transcriptional level, conflicting data are available on a possible post-translational regulation of alpha 1(I) collagen gene expression. In this study we demonstrate by comparing a commonly used alpha 1(I) cDNA probe from the 3' end of the alpha 1(I) mRNA with a newly prepared alpha 1(I) cDNA probe from the 5' end (p1E1) that--in contrast to previous reports--chicken sternal chondrocytes do not contain untranslated alpha 1(I) mRNA which may become translatable after RA treatment. By in situ hybridization we show the absence of cytoplasmic alpha 1(I) mRNA from chondrocytes and its presence in the perichondrium of sternal cartilage. Perichondral cells might have contaminated sternal chondrocyte preparations, explaining low levels of alpha 1(I) mRNA seen by Northern hybridization and RNase protection assays of chicken sternal cartilage mRNA even with the p1E1 probe. We show by Northern hybridization and metabolic labeling with 3H-proline followed by SDS-gel electrophoresis that retinoic acid at 3 microM suppresses type II, IX, and X collagen gene expression within 2 days both at the mRNA and protein level and induces the onset of alpha 1(I), alpha 2(I), and alpha 1(III) expression within 3 days. No expression of CRABP, the cellular retinoic acid binding protein, was seen in RA-treated or control chondrocytes, indicating that CRABP protein is not involved in the RA-induced modulation of the chondrocytes.

Influence of perinatal risk factors on the involution of the irido-pupillary membrane

The aim of this study was to assess the influence of common perinatal risk factors on the disappearance of the anterior vascular capsule of the lens (AVCL). Direct ophthalmologic examinations were performed on 75 neonates (27 to 35 weeks gestational age) in the first 24 hours after birth, using the degree of involution of the AVCL to estimate gestational age in high risk pregnancy. Our results show that the gradual disappearance of the AVCL is not influenced by perinatal risk factors, such as maternal preeclampsia, prenatal administration of steroids, neonatal infection and low birth weight, confirming the clinical value of this test in the assessment of gestational age in high risk babies.

Percutaneous transluminal coronary rotary ablation with Rotablator (European experience)

This study reports the results from 3 European centers using rotary ablation with Rotablator, a device that is inserted into the coronary artery and removes atheroma by grinding it into millions of tiny fragments. Rotary ablation was performed in 129 patients. Primary success (reduction in percent luminal narrowing greater than 20%, residual stenosis less than 50%, without complications) was achieved by rotary angioplasty alone in 73 patients (57%). An additional 38 patients (29%) had successful adjunctive balloon angioplasty. Thus primary success was achieved in 111 patients (86%) at the end of the procedure. Acute occlusion occurred in 10 patients (7.7%). Recanalization was achieved by balloon angioplasty in 7: urgent bypass grafting was undertaken in 2. Q-wave and non-Q-wave myocardial infarction occurred in 3 and 7 patients, respectively. No deaths occurred. Follow-up angiography was performed in 74 patients (60%). Restenosis, defined as the recurrence of significant luminal narrowing (greater than 50%) occurred in 17 of 37 patients (46%) who underwent rotary ablation alone, and 11 of 37 patients (30%) who had adjunctive balloon angioplasty. The overall angiographic restenosis rate was 37.8%. In conclusion, rotary ablation is technically feasible, and relatively safe in the coronary circulation. The low primary success rate reflects the limited size of the device, which can be introduced through available guiding catheters, and limits the use of rotary ablation as a stand-alone procedure to lesions in small arteries or in distal locations. No reduction in restenosis was seen, but the role of this device combined with balloon angioplasty in larger arteries needs to be further defined.

[Percutaneous sonographic angioplasty. Initial experimental results]

Aim of the present study was to examine in vitro the effects of a new ultrasound catheter system on atherosclerotic and normal vessels before employing the system in humans. 141 attempts were made on 32 vascular preparations obtained at autopsy. The vessels were opened longitudinally within 24 hours of death, dilated with gelatine and were then "treated" in a waterbath using varying degrees of pressure, angle of incidence, sound intensity and duration of sound. Macroscopic and histological examinations of the preparation showed no morphological change in normal vessels except evidence of pressure by the catheter. In particular, there were no perforations of the vessel wall. In atherosclerotic segments there was significant reduction in the size of plaques following treatment.

Short and long term results after intracoronary stenting in human coronary arteries: monocentre experience with the balloon-expandable Palmaz-Schatz stent

OBJECTIVE

Intracoronary stenting was designed to overcome acute complications after percutaneous transluminal coronary angioplasty and to achieve a reduced rate of restenosis, both of which are major limitations of this well accepted method for treating coronary heart disease. This report describes the experience at one centre with the implantation of balloon-expandable Palmaz-Schatz stents and focuses on device related complications and the short and long term angiographic outcome.

DESIGN

A retrospective data analysis.

PATIENTS

Stenting was attempted in 50 patients. Restenosis after an initially successful angioplasty procedure, inadequate postangioplasty results, saphenous coronary bypass stenoses, and bail-out situations were regarded as indications.

MAIN OUTCOME MEASURES AND RESULTS

In 49 of 50 attempted patients 61 stents (1-4 per patient) were implanted. Delivery problems occurred in three patients and were successfully overcome in two patients. Bail-out situations were successfully managed in 16 patients. Complications included acute thrombus formation within the stent immediately after implantation in one patient, which was successfully treated by thrombolysis. One patient was sent for bypass surgery the day after implantation; another died 10 days after implantation for unknown reasons. Subacute stent thrombosis occurred in seven patients 5-9 days after implantation and was successfully treated by thrombolysis or balloon angioplasty in five patients. Bleeding complications occurred in nine patients, five of whom required blood transfusions. Angiography showed long term vessel patency after 4-6 months in 31 (76%) of the 41 patients who were followed up, restenosis in six (14%), and reocclusion in four (10%). Late restenosis or reocclusion was found in five (15%) of 33 patients with a single stent in contrast to five (63%) of eight patients with multiple stents.

CONCLUSIONS

Balloon-expandable intracoronary stenting is a feasible method for treating the acute complications of balloon angioplasty. It reduced the rate of restenosis for single stent implantation. Subacute thrombotic events must be regarded as previously unknown and serious complications.

Results of intracoronary stents for management of coronary dissection after balloon angioplasty

Dissections after coronary balloon angioplasty are risk factors for acute or subacute vessel closures. Intracoronary stenting was developed to avoid these complications by pressing the intimal and medial flaps against the vessel wall, thus reducing the risk of acute thrombosis. A total of 22 stents were implanted into the coronary arteries of 15 patients with dissections after balloon angioplasty causing angina pectoris or ischemic electrocardiographic changes. Stent delivery was successful in all cases. In 1 patient acute stent thrombosis was documented and treated successfully by thrombolytic therapy. Another patient underwent coronary artery bypass surgery 24 hours later because of persisting angina. Angiograms after 24 hours documented vessel patency in the remaining 14 patients. Late control angiograms after 4 to 6 months were obtained in 12 of 14 patients. Vessel patency without significant restenosis was observed in 8 patients, restenosis in 3 and reocclusion in 1 patient. All 3 patients with multiple stent implantation had restenosis (n = 2) or reocclusion (n = 1), compared with 1 patient with single stent implantation. Thus, intracoronary stenting appears to be a secure and effective method of handling bailout situations caused by dissection after balloon angioplasty, with good long-term results when only a single stent is implanted.

[Angiographic and histologic findings in high frequency rotational ablation in coronary arteries in vitro]

High-frequency rotational angioplasty is a recently developed method for coronary angioplasty in the catheter laboratory. An elliptical burr tip (phi 1.25-2.0 mm) with embedded diamant chips (phi 40-50 microns) is rotated by a helical drive shaft at 150,000-180,000 rpm. The burr is advanced over a 0.009-inch coaxial guide wire. To show the effects of this approach in diseased and healthy vessels, which may be present before and behind a stenosis, 17 atherosclerotic coronary arteries of nine human hearts, and 18 normal coronary arteries of nine pig hearts were treated by this method in vitro. Standardized coronary angiography was performed before and after Rotablator treatment, followed by histological examination. From these data the burr-to-vessel-diameter ratio was calculated for each vessel segment and compared with the angiographical and histological outcome. Partial or complete removal of the circumference of the innermost vessel wall layers was observed regularly. The average removal of tissue in human coronary arteries was limited to the intimal layer and in the pig coronary arteries to the internal elastic membrane. In the pig coronary arteries no intimal tears or dissections occurred, in human coronary arteries tears could be seen frequently (13 of 17 vessels (76%)). Media tears were observed in 3 of 17 vessels; one (2%) media dissection could be demonstrated; no perforation occurred. Thus, the in vitro studies suggest that coronary rotational angioplasty has only a slight effect on the vessel segment next to a stenosis, regardless of the burr-to-vessel-diameter ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary stent implantation in acute vessel closure 48 hours after an unsatisfactory coronary angioplasty

We report the implantation of a balloon-expandable stent in a patient with acute vessel closure in the state of evolving myocardial infarction following 48 hr after unsatisfactory coronary angioplasty. The stent was implanted after successful recanalization of an occluded left anterior descending artery, with repeated unsatisfactory results of balloon angioplasty. Adjunct thrombolytic therapy was contraindicated. No residual stenosis was documented in immediate control angiograms, or after 24 hr, 3 weeks, and 4 months.