Stents covered by autologous venous grafts: feasibility and immediate and long-term results

BACKGROUND

Previous experimental studies with a new covered stent, the autologous venous graft-covered stent (AVGCS), have shown favorable results. The aim of this study was to evaluate the feasibility and safety of this new technique in human coronary arteries and to compare the long-term outcome with uncovered stents.

METHODS AND RESULTS

A venous graft was removed from an upper limb. A conventional stent then was covered by the venous graft. Fifty-eight AVGCS were implanted in 56 patients, including 16 patients with acute coronary syndromes (ACS). Additionally, in 114 patients, 138 uncovered stents were implanted, serving as a control group, including 38 patients with ACS. The procedure was successful in all patients. Stent thrombosis was observed in 3 patients in the control group and in 1 patient with an AVGCS. There was a trend for the minimal luminal diameter to be greater in the AVGCS group at follow-up (P =.07), and statistical significance was observed in patients with ACS (P <.01). The target vessel revascularization and the restenosis rates were similar between the 2 groups. In patients with ACS, the restenosis rate was less (P <.04) and there was a trend for target vessel revascularization to be less in covered stents (P =.09). The event-free survival rate at 4 years was 85% in the AVGCS group versus 81% in the control group (P = not significant); in ACS it was 94% versus 78%, respectively (P = not significant). Stents covered by thicker venous grafts were associated with improved clinical outcome.

CONCLUSIONS

Stents covered by autologous venous grafts may be safely prepared without complications. This technique may prove to be a useful means, especially in patients with ACS.

Heat production of atherosclerotic plaques and inflammation assessed by the acute phase proteins in acute coronary syndromes

Several studies have shown that inflammation plays an important role in the pathogenesis of coronary heart disease (CHD). Serum amyloid A (SAA) and C-reactive protein (CRP) reactants of the acute phase of inflammation, have been shown to be increased in patients with CHD. Recently ex vivo studies demonstrated that some types of atherosclerotic plaques show substantially warmer regions. A catheter-based technique has been developed to measure the temperature of human arteries in vivo. Therefore, the aim of the present study was to measure the luminal surface temperature in patients with CHD and to correlate it with the acute phase proteins in order to discriminate the role of inflammation in heat production in acute coronary syndromes. Sixty patients were studied with CHD (20 with stable angina, 20 with unstable angina and 20 with acute myocardial infarction) and 20 sex- and age-matched controls without coronary artery disease, by measuring plasma levels of SAA, CRP, plasma lipids and intracoronary arterial luminal wall temperature. Intracoronary temperature was measured with a thermography catheter developed in our Institution: a thermistor probe with a temperature accuracy of 0.05 degrees C, was attached at the distal end of a long 3F polyurethane shaft. It was found that the median temperature differences at the site of the lesion from the core temperature was increased in patients with unstable angina (1.025 degrees C) and acute myocardial infarction (2.150 degrees C) compared with stable angina (0.300 degrees C), P<0.001 for each comparison. Furthermore, stable angina has increased temperature differences compared with controls (0.200 degrees C, P<0.001). There were very good correlations between CRP and SAA with the temperature (r=0.796, P=0.01 and r=0.848, P=0.01, respectively). Local heat at the site of lesion is increased in patients with acute coronary syndromes and may arise from an aggressive inflammatory response occurring in these situations. The sensitive measurement of plaque temperature as a prognostic marker may be useful in the management of coronary heart disease.

Implantation of stents covered by autologous arterial grafts in human coronary arteries: a new technique

A renewed interest in radial artery conduits for bypass surgery has emerged during the last few years. In order to combine a surgical with a percutaneous technique, stents were covered by radial arterial grafts. The purpose of this study was to evaluate the feasibility of, and the immediate and long-term results after, intracoronary implantation of stents covered by autologous arterial grafts.

METHODS

A graft was removed from the radial artery. A conventional stent was then covered by the arterial graft. The autologous arterial graft was stabilized on the stent by sutures. Fifteen covered stents were implanted in 15 patients (56.1 +/- 17.3 years old) in all coronary vessels.

RESULTS

The procedure of stent covering was feasible and short in duration. Procedural success was 100% with no in-hospital stent thrombosis, Q-wave myocardial infarction or death. In 14 patients (93.3%), including the patients with clinical restenosis, a repeat angiography was performed (minimum lumen diameter immediately after procedure: 3.01 +/- 0.22 mm, at follow-up: 2.56 +/- 0.90 mm). Target lesion revascularization was required in 2 patients. The event-free survival rate at 2 years was 87%.

CONCLUSION

Intracoronary implantation of stents covered by an autologous arterial graft may be performed safely with excellent long-term results. A multicenter study is required to assess the efficacy.

Thermal heterogeneity within human atherosclerotic coronary arteries detected in vivo: A new method of detection by application of a special thermography catheter

BACKGROUND

Activated macrophages play an important role in the pathogenesis of acute ischemic syndromes. It has been postulated that detection of heat released by activated inflammatory cells of atherosclerotic plaques may predict plaque rupture and thrombosis. Previous ex vivo studies have shown that there is thermal heterogeneity in human carotid atherosclerotic plaques.

METHODS AND RESULTS

To measure the temperature of human arteries in vivo, we developed a catheter-based technique. Ninety patients (45 with normal coronary arteries, 15 with stable angina [SA], 15 with unstable angina [UA], and 15 with acute myocardial infarction [AMI]) were studied. The thermistor of the thermography catheter has a temperature accuracy of 0.05 degrees C, a time constant of 300 ms, and a spatial resolution of 0.5 mm. Temperature was constant within the arteries of the control subjects, whereas most atherosclerotic plaques showed higher temperature compared with healthy vessel wall. Temperature differences between atherosclerotic plaque and healthy vessel wall increased progressively from SA to AMI patients (difference of plaque temperature from background temperature, 0. 106+/-0.110 degrees C in SA, 0.683+/-0.347 degrees C in UA, and 1. 472+/-0.691 degrees C in AMI). Heterogeneity within the plaque was shown in 20%, 40%, and 67% of the patients with SA, UA, and AMI, respectively, whereas no heterogeneity was shown in the control subjects.

CONCLUSIONS

Thermal heterogeneity within human atherosclerotic coronary arteries was shown in vivo by use of a special thermography catheter. This heterogeneity is larger in UA and AMI, suggesting that it may be related to the pathogenesis.

Stents covered by an autologous arterial graft in porcine coronary arteries: feasibility, vascular injury and effect on neointimal hyperplasia

OBJECTIVE

The use of stents has improved results after balloon coronary angioplasty. Several materials have been proposed for covering the metallic surface of the stent to reduce the rate of subacute thrombosis and restenosis. In our institution, an autologous arterial graft was used for covering the external surface of a conventional stent. The angiographic and histological response in a porcine coronary artery model was investigated.

METHODS

An autologous arterial graft was removed from the femoral artery and carefully prepared. Subsequently, a conventional stent was covered externally by the arterial graft. Twenty-two covered stents and 22 uncovered regular stents were implanted alternatively in the coronary arteries of 22 pigs. One animal died immediately after the procedure, due to thrombus formation in the uncovered stent. Six animals were sacrificed at seven days and the remaining animals were sacrificed at two months. Before the sacrifice, coronary angiography was performed in all animals.

RESULTS

Thrombosis was detected in two control segments and in one covered stented segment. After seven days, the luminal surface of the covered stents was covered by a new endothelial layer in contrast to partial endothelial cell appearance in the control group. The angiographic parameters were similar between the two groups. Histologically, the covered stents were associated with less vascular injury compared to uncovered stents. In covered stents a trend towards reduction of maximal intimal hyperplasia was detected (covered: 116.6 +/- 47.75 vs uncovered: 150.25 +/- 46.81 microns, p = 0.08); also the thickness of the arterial media was reduced (covered: 21.34 +/- 10.28 vs uncovered: 102.63 +/- 18.71 microns, p = 0.02). The luminal and vessel areas were similar in the two groups.

CONCLUSIONS

The preparation and implantation of the autologous arterial graft-covered stent is technically safe and feasible. This type of covered stent results in accelerated endothelialization, less vascular injury, thinning of the arterial media and a trend to reduce the intimal hyperplasia in normal coronary arteries.

Effects of ventricular pacing-induced tachycardia on aortic mechanics in man

OBJECTIVE

Effects of pacing-induced tachycardia on left ventricular function have been studied extensively. However, little attention has been focused on aortic elastic properties during heart rate increments. The aim was to determine the effects of right ventricular pacing on the aortic elastic properties.

METHODS

We studied 14 normal subjects (baseline blood pressure, 129/84 +/- 10/6 mmHg; aortic diameter, 23.5/21.3 +/- 2.4/1.9 mm) at rest, during rapid right ventricular pacing (at five stepwise heart rate increases of 20 bpm every 2 min) and after 5 min recovery. Shifts as well as changes in the slope and the stiffness constant of the pressure diameter (p-d) relation, derived from simultaneous tip-micromanometer aortic pressure recordings and high-fidelity ultrasonic intravascular aortic diameter recordings, were used as indices of aortic stiffness. Wave reflection was also studied.

RESULTS

Aortic pulse pressure and strain significantly decreased after pacing-induced tachycardia (p < 0.0001 and < 0.05, respectively). During pacing, the slope of the linear p-d relation as well as the stiffness constant were decreased, followed by increases at recovery (p < 0.0001). The augmentation index and the aortoventricular coupling ratio were significantly decreased (p < 0.0001).

CONCLUSIONS

Pacing-induced increases in pulse frequency may result in improved aortic distensibility and aortoventricular coupling.

Effects of balloon mitral valvuloplasty on left atrial function in mitral stenosis as assessed by pressure-area relation

OBJECTIVES

This study sought to investigate the changes induced on the pressure-area relation of the left atrium in patients with mitral stenosis after percutaneous balloon mitral valvuloplasty.

BACKGROUND

Left atrial (LA) function is influenced by changes in LA afterload. The latter is increased in mitral stenosis as a result of increased resistance to blood flow imposed by the stenotic mitral valve.

METHODS

We studied the effects of acute alterations of LA afterload induced by retrograde nontransseptal balloon mitral valvuloplasty (RNBMV) on LA function in patients with mitral stenosis. LA pressure-area relations were obtained in 15 patients with mitral stenosis (8 with sinus rhythm, 7 with atrial fibrillation) before and after valvuloplasty, as well as in 15 normal subjects. LA pressure was recorded by a catheter-tipped micromanometer introduced retrogradely into the left atrium while LA area was recorded simultaneously using acoustic quantification. The areas of the A and V loops of the pressure-area relation as well as the LA chamber stiffness constant were calculated.

RESULTS

Balloon valvuloplasty resulted in a significant increase in mitral valve area (p < 0.001) and a substantial reduction of the mean transmitral pressure gradient (p < 0.001) and mean LA pressure (p < 0.001). The area of the A loop in patients with sinus rhythm and the area of the V loop in those with atrial fibrillation increased significantly after completion of the procedure (p < 0.001). Furthermore, LA stiffness decreased in both groups.

CONCLUSIONS

After RNBMV, there is a significant increase in LA pump function in patients with sinus rhythm, a significant increase in LA reservoir function in patients with atrial fibrillation and a significant reduction in LA stiffness in all patients. Marked alterations of the configuration of the LA pressure-area relation occur immediately after successful RNBMV in patients with mitral stenosis.

Unfavorable effects of passive smoking on aortic function in men

BACKGROUND

The aorta acts as both a conduit and an elastic buffering chamber that modulates left ventricular function and coronary blood flow. Previous studies have shown that active smoking has unfavorable effects on aortic elasticity.

OBJECTIVE

To study the association between passive smoking and the elastic properties of the human aorta.

DESIGN

Comparison of nonsmokers during passive smoking studies and smokers during active smoking or sham smoking studies.

SETTING

Academic medical center.

PARTICIPANTS

16 male nonsmokers were assigned to passive smoking studies, and 32 current, long-term, male smokers were randomly assigned to either active smoking (16 patients) or sham smoking (16 patients) studies.

INTERVENTION

All participants underwent diagnostic catheterization. In the passive smoking group, environmental tobacco smoke was vented into an exposure chamber for 5 minutes (mean carbon monoxide level, 30 parts per million). Each participant in the active smoking group smoked one filtered cigarette (1.0 mg of nicotine) under standardized conditions within 5 minutes; each participant in the sham smoking group performed a similar pattern of inhalation with one unlit cigarette.

MEASUREMENTS

Aortic elastic properties were studied by measuring the aortic pressure-diameter relation before and for 20 minutes after passive, active, or sham smoking. Instantaneous diameter of the thoracic aorta was measured with a high-fidelity ultrasonic dimension catheter. Instantaneous aortic pressure and diameter were measured at the same site.

RESULTS

Both passive and active smoking were associated with changes in the aortic pressure-diameter relation (change in mean distensibility in the passive smoking group, from 2.02 to 1.59 x 10(-6) cm2 x dyne(-1) [for comparisons of time course between passive and sham smoking groups, P < 0.001]; change in mean distensibility in the active smoking group, from 2.08 to 1.51 x 10(-6) cm2 x dyne(-1) [for comparisons of time course between active and sham smoking groups, P < 0.001]). These changes represent decreases of 21% and 27%, respectively. No changes in aortic elasticity were seen in the sham smoking group.

CONCLUSIONS

Both passive and active smoking are associated with an acute deterioration in the elastic properties of the aorta. This association between exposure to tobacco smoke and aortic elasticity indicates that aortic function deteriorates during passive or active smoking.

Total reconstruction of a diseased saphenous vein graft by means of conventional and autologous tissue-coated stents

This is the first report of a total reconstruction of a diseased saphenous vein graft, with thrombus-containing lesion and multiple stenoses, by the implantation of arterial graft- and venous graft-coated stents, and of conventional stents. The procedure was successful without any complications, and follow-up angiography after 6 months revealed patency of the vessel.

Assessment of left atrial pressure-area relation in humans by means of retrograde left atrial catheterization and echocardiographic automatic boundary detection: effects of dobutamine

OBJECTIVES

This study sought to validate and apply a new method for obtaining the left atrial (LA) pressure-area relation.

BACKGROUND

In physiologic investigations, the pressure-area relation is the most accurate and representative index of LA hemodynamic status.

METHODS

We applied real-time two-dimensional echocardiographic imaging with automatic boundary detection to estimate LA area changes. To obtain LA pressure, a catheter-tipped micromanometer was introduced retrogradely into the left atrium using a steerable cardiac catheter developed at our institution. Twenty-five patients (11 normal subjects, 7 patients with an enlarged left atrium due to heart failure, 7 patients with atrial fibrillation) were studied before and after dobutamine administration. From the LA pressure-area relation, the area of the A loop (the first counterclockwise loop) and the V loop (the second clockwise loop), the pressure-minimal area relation and the LA passive elastic chamber stiffness constant were measured.

RESULTS

Normalized pressure-minimal area relation was highly linear and sensitive to changes in inotropic state (normal subjects: from 0.96 to 1.27 mm Hg/cm2, p < 0.01; patients with heart failure: from 0.59 to 0.68 mm Hg/cm2, p = NS; patients with atrial fibrillation: from 0.80 to 1.06 mm Hg/cm2, p < 0.05). The LA stroke work index was accurately calculated, and a very good correlation was found with LA preload. LA stroke work index was lower in patients with heart failure (3.9 +/- 0.8 cm2 x mm Hg, p < 0.001), whereas the LA stiffness constant was increased in patients with heart failure (0.801 +/- 0.097 cm(-2), p < 0.01) and atrial fibrillation (0.796 +/- 0.091 cm(-2), p < 0.01) compared with normal subjects (stroke work index 7.3 +/- 1.9 cm2 x mm Hg, stiffness constant 0.623 +/- 0.107 cm(-2), respectively). In addition, increased inotropic state after dobutamine administration resulted in improved LA pump function (stroke work index) in normal subjects (from 10.2 +/- 0.9 to 13.8 +/- 1.9 cm2 x mm Hg, p < 0.001) and patients with heart failure (from 4.3 +/- 0.4 to 7.6 +/- 0.4 cm2 x mm Hg, p < 0.001), as well as in decreased stiffness constant in all groups of patients (normal subjects: from 0.712 +/- 0.141 to 0.473 +/- 0.089 cm(-2); patients with heart failure: from 0.896 +/- 0.181 to 0.494 +/- 0.093 cm(-2); patients with atrial fibrillation: from 0.779 +/- 0.145 to 0.467 +/- 0.086 cm(-2), p < 0.001).

CONCLUSIONS

The method described here is both safe and reproducible for obtaining the LA pressure-area relation. LA function is impaired in patients with heart failure and in those with atrial fibrillation and may be acutely improved with inotropic agents in both normal and diseased atria.

Aortic function in arterial hypertension determined by pressure-diameter relation: effects of diltiazem

BACKGROUND

Aortic elastic properties, important determinants of left ventricular function and coronary blood flow, are compromised in hypertension. The aim of this study was to determine aortic function in hypertensive patients and in normal subjects before and after administration of diltiazem, a calcium antagonist widely used in the treatment of essential hypertension.

METHODS AND RESULTS

The aortic pressure-diameter relation was obtained before and after diltiazem administration in 15 hypertensives and 15 control normotensives. Instantaneous diameter of the thoracic aorta was acquired with a high-fidelity intravascular catheter developed in our institution and previously validated. Instantaneous aortic pressure was measured simultaneously and at the same aortic level with a catheter-tip micromanometer. Energy loss due to the viscosity of aortic wall was measured from the area of the loop. Aortic distensibility was calculated using the formula 2 x (pulsatile change in aortic diameter)/([diastolic aortic diameter] x [aortic pulse pressure]). At baseline, aortic distensibility was lower and energy loss was greater in hypertensives than in normotensives (distensibility: 1.4+/-0.3 versus 3.5+/-0.7 cm2 x dyne(-1) x 10(-6), respectively, P<.001; energy loss: 14.1+/-3.3 versus 8.2+/-2.2 mm x mm Hg, respectively, P<.001). After diltiazem administration, aortic distensibility was increased, whereas energy loss was decreased in both hypertensives (peak response: distensibility, 2.0+/-0.4 cm2 x dyne(-1) x 10(-6), P<.001; energy loss, 9.3+/-1.6 mm x mm Hg, P<.001) and normotensives (peak response: distensibility, 5.2+/-0.5 cm2 x dyne(-1) x 10(-6), P<.001; energy loss, 5.0+/-1.2 mm x mm Hg, P<.001).

CONCLUSIONS

Aortic elastic properties are compromised and energy loss due to aortic wall viscosity is increased in hypertensives compared with normotensives. Function of the aorta is improved in both hypertensive and normotensive subjects after the administration of diltiazem.

Arterial autologous graft-stent for treatment of coronary artery disease: a new technique

The radial artery has been used as a free bypass graft with excellent results. An autologous vein graft-coated stent, a novel type of stent developed at our institution, has been applied successfully under both experimental and clinical conditions. To extend the spectrum of biological linings for coated stents, we used an arterial graft. We describe the first application of the radial artery as an autologous coating for a conventional stent to be used in treatment of coronary artery disease.

Unfavorable effect of smoking on the elastic properties of the human aorta

BACKGROUND

Smoking is a major risk factor for cardiovascular morbidity and mortality. Because previous studies have shown that smoking affects vasomotor response, we hypothesized that smoking may also acutely alter aortic elastic properties.

METHODS AND RESULTS

We studied 40 male current and long-term smokers who underwent diagnostic cardiac catheterization for chest-pain evaluation. Twenty subjects (age, 48 +/- 2 years, mean +/- SEM) were randomly assigned to smoking and 20 (age, 47 +/- 2 years) to sham smoking studies. Aortic elastic properties were studied with the determination of the aortic pressure-diameter relation before smoking, every minute for the first 5 minutes after the initiation of smoking or sham smoking, and every 5 minutes for the following 15 minutes. Instantaneous diameter of the thoracic aorta was measured with a special ultrasonic dimension catheter developed in our laboratory and previously validated. Instantaneous aortic pressure was measured at the same site as was diameter with a Millar micromanometer. Smoking was associated with significant changes in the aortic pressure-diameter relation that denote deterioration of the elastic properties and were maintained during the whole study period: the slope of the pressure-diameter loop became steeper (baseline, 35.43 +/- 1.38; minute 1, 45.26 +/- 1.65; peak at minute 10, 46.36 +/- 1.69 mm Hg/mm; P < .001) and aortic distensibility decreased (baseline, 2.08 +/- 0.12; minute 1, 1.60 +/- 0.08; nadir at minute 5, 1.54 +/- 0.07 x 10(-6) cm2.dyne-1; P < .001). In contrast, no changes in aortic elasticity indexes were observed with sham smoking.

CONCLUSIONS

Smoking is associated with an acute deterioration of aortic elastic properties. This effect of smoking may contribute to the unfavorable consequences of smoking on the cardiovascular system.

Autologous vein graft-coated stents for the treatment of thrombus-containing coronary artery lesions

Recent studies have shown that stents may have a potential role in the treatment of thrombus-containing lesions. We report on the application of an autologous vein graft-coated stent (AVGCS) as the primary therapeutic modality for acute myocardial infarction in 10 patients. AVGCS delivery and deployment were successful and uneventful. Mean minimal lumen diameter and TIMI trial flow grade increased significantly (from 0.04 +/- 0.09 mm pre-AVGCS to 3.02 +/- 0.32 mm post-AVGCS, and from 10 patients with flow grade 0-1 pre-AVGCS to 10 patients with flow grade 3 post-AVGCS, respectively). Ten-day angiogram revealed maintenance of the immediate results. Nine patients had a negative exercise stress test 2 mo post-AVGCS, and at a mean follow-up of 30 +/- 7 weeks, all 9 were symptom-free. One patient, 3 wk after implantation and while being hospitalized for hypovolemic shock, developed recurrent infarction. These favorable preliminary outcomes suggest that AVGCS may play a useful role in the treatment of thrombus-containing lesions.

Unfavorable effect of smoking on the elastic properties of the human aorta

BACKGROUND

Smoking is a major risk factor for cardiovascular morbidity and mortality. Because previous studies have shown that smoking affects vasomotor response, we hypothesized that smoking may also acutely alter aortic elastic properties.

METHODS AND RESULTS

We studied 40 male current and long-term smokers who underwent diagnostic cardiac catheterization for chest-pain evaluation. Twenty subjects (age, 48 +/- 2 years, mean +/- SEM) were randomly assigned to smoking and 20 (age, 47 +/- 2 years) to sham smoking studies. Aortic elastic properties were studied with the determination of the aortic pressure-diameter relation before smoking, every minute for the first 5 minutes after the initiation of smoking or sham smoking, and every 5 minutes for the following 15 minutes. Instantaneous diameter of the thoracic aorta was measured with a special ultrasonic dimension catheter developed in our laboratory and previously validated. Instantaneous aortic pressure was measured at the same site as was diameter with a Millar micromanometer. Smoking was associated with significant changes in the aortic pressure-diameter relation that denote deterioration of the elastic properties and were maintained during the whole study period: the slope of the pressure-diameter loop became steeper (baseline, 35.43 +/- 1.38; minute 1, 45.26 +/- 1.65; peak at minute 10, 46.36 +/- 1.69 mm Hg/mm; P < .001) and aortic distensibility decreased (baseline, 2.08 +/- 0.12; minute 1, 1.60 +/- 0.08; nadir at minute 5, 1.54 +/- 0.07 x 10(-6) cm2.dyne-1; P < .001). In contrast, no changes in aortic elasticity indexes were observed with sham smoking.

CONCLUSIONS

Smoking is associated with an acute deterioration of aortic elastic properties. This effect of smoking may contribute to the unfavorable consequences of smoking on the cardiovascular system.

Stents wrapped in autologous vein: an experimental study

OBJECTIVES

A new type of coated stent, consisting of a conventional stent covered by an autologous vein graft, was developed at our institution.

BACKGROUND

Coated stents are under investigation to address stenting limitations. However, experimental implantation of coated stents covered by autologous tissue has not been reported.

METHODS

An autologous vein graft was removed and carefully prepared. Subsequently, a Palmaz stent was covered by the vein graft both internally and externally. Twenty-seven stents were implanted in the normal iliac arteries of 27 pigs weighing 18 to 33 kg. In 15 of the pigs, 15 noncoated Palmaz stents were implanted in the contralateral artery; these animals served as the control group. The animals were followed up angiographically for a period ranging from 7 days to 6 months. At the time of death, the stented segments were removed, and histomorphometric analysis was performed.

RESULTS

Autologous vein graft-coated stent preparation and implantation was feasible and uncomplicated. In both stents, angiographic follow-up revealed the absence of thrombosis, except for two cases of subacute thrombosis in the control group. The thickness of the intimal layer was greater in the coated stents and seems to be due to the existence of the internal vein layer ([mean +/- SD] 0.57 +/- 0.12 vs. 0.27 +/- 0.13 mm, p = 0.001). The arterial media of the coated stent segments was thinner than that in the control group (0.14 +/- 0.03 vs. 0.18 +/- 0.01 mm, p = 0.02).

CONCLUSIONS

The autologous vein graft-coated stent seems to be nonthrombogenic, and only minimal hyperplasia was observed in the pigs. Further studies are needed to explore the efficacy of this technique in humans.

Autologous vein graft-coated stent for treatment of coronary artery disease

Acute or subacute thrombosis and late restenosis remain the main limitations of permanent stenting. In an effort to address these limitations, an autologous vein graft-coated stent (AVGCS) was developed at our institution. This stent consists of a conventional stent (Palmaz or Palmaz-Schatz, Johnson and Johnson), which is covered by an autologous vein graft. After successful experimental implantation, we report here the immediate results of the percutaneous implantation of AVGCS in 7 patients with coronary artery disease (6 de novo lesions and 1 bailout case). The results of this preliminary study indicate that the preparation of the AVGCS is easy and feasible. The implantation of the AVGCS was uncomplicated, and the immediate angiographic results were excellent. This new type of coated stent may be useful in addressing current limitations of balloon angioplasty.

A new adjustable temporary stent catheter for management of acute dissection during balloon angioplasty

Acute coronary dissection remains a limitation of percutaneous transluminal coronary angioplasty. For the management of acute coronary dissection, a new adjustable temporary stent catheter that can be positioned to the lesion, deployed, and retrieved at a later stage was developed. This catheter has at its distal end a spiral stent that can be reduced and expanded in a controlled fashion by external manipulations. The adjustable temporary stent catheter was applied in three clinical cases with acute coronary dissection during balloon angioplasty. In all cases, the adjustable temporary stent catheter restored blood flow when it was expanded to the lesion for 60 min and this restoration was maintained after device removal. It is envisioned that this temporary stent device may prove a useful means for the treatment of acute coronary dissection during percutaneous transluminal coronary angioplasty.

Pressure-diameter relation of the human aorta. A new method of determination by the application of a special ultrasonic dimension catheter

BACKGROUND

Pressure-diameter relation of the aorta provides important information about the elastic properties of the vessel. However, owing to methodological limitations, data regarding this relation are limited in conscious humans. In the present study, we assessed a new method for the direct estimation of the elastic properties of the aorta in conscious humans by simultaneous acquisition of instantaneous aortic pressure and diameter.

METHODS AND RESULTS

With this method, instantaneous diameter of the thoracic aorta was acquired by a newly designed intravascular catheter developed in our institution that incorporates an ultrasonic displacement meter at its distal end. Instantaneous aortic pressure was acquired simultaneously at the same aortic level with a catheter-tip micromanometer. Aortic pressure-diameter loops were derived from computer analysis of data. After in vitro and animal testing, elastic properties of the aorta were investigated in coronary artery disease (CAD) patients (n = 15) and compared with those of control subjects (n = 10). Aortic distensibility was less in the CAD group than in the control group (1.73 +/- 0.33 versus 3.95 +/- 1.09 x 10(-6) x cm2 x dyne-1, P < .001). Compared with control subjects, the mean value of the slope of the pressure-diameter loops was significantly greater in the CAD group (38.89 +/- 8.75 versus 19.62 +/- 5.46 mm Hg.mm-1, P < .001), whereas the mean value of the intercept was lower in this latter group of patients (-785.60 +/- 177.55 versus -313.43 +/- 126.41 mm Hg, P < .001). An excellent correlation was found between the slope of pressure-diameter loop and age in the group of control subjects (r = .827). Ninety-three percent of the patients with CAD had values above the upper 95% confidence limits of the control subjects (P < .001). In a third group of patients (n = 16) in whom assessment of pulse wave velocity was also included in the study of the elastic properties of the aorta, pulse wave velocity had a strong inverse correlation with aortic distensibility (r = -.95) and a strong positive correlation with the slope of the pressure-diameter loop (r = .97).

CONCLUSIONS

This new method of determination of pressure-diameter of the aorta enables an accurate and reliable evaluation of the elastic properties of the aorta in conscious humans and may be useful for a profound study of human aorta mechanics.

Effect of vasa vasorum flow on structure and function of the aorta in experimental animals

BACKGROUND

It is known that vasa vasorum flow contributes substantially to the nutrition of the outer layers of the thoracic aorta. This investigation was undertaken to test the hypothesis that impairment of vasa vasorum flow would alter the structure of the aortic wall and change the elastic properties of the aorta.

METHODS AND RESULTS

The periaortic fat that contain the vasa vasorum for the ascending aorta was removed in seven anesthetized dogs, and the results were compared with those obtained from six weight-matched sham-operated control dogs. Aortic pressures, aortic diameters, and aortic distensibility were obtained before and 30 minutes and 15 days after removal of the periaortic vasa vasorum network. Aortic pressures were measured directly with a fluid-filled catheter. Aortic diameters were measured simultaneously with aortic pressures with an elastic, air-filled ring connected to a transducer. Aortic distensibility was calculated by the formula 2 x pulsatile change in aortic diameter/(diastolic aortic diameter x pulse pressure). Histology was performed in transverse blocks of aortic wall at the end of the experiment in both groups. The efficacy of the technique for the interruption of vasa vasorum blood supply to the aortic wall was demonstrated by histology in four additional animals that were killed without removal of vasa vasorum (two animals) and immediately after vasa vasorum removal (two animals). At baseline, heart rate, aortic pressures, aortic diameters, and aortic distensibility were similar in the two groups. A significant decrease in aortic distensibility was observed 30 minutes and 15 days after removal of the vasa vasorum in the experimental group (baseline, 3.453 +/- 1.023; 30 minutes, 2.521 +/- 0.760; 15 days, 1.586 +/- 0.488 10(-6).cm2.dyn-1; F = 9.532, P < .001). No changes were observed in aortic distensibility in the control group during the experiment. Histology of the aorta revealed medial necrosis, alterations of the elastin fibers, and a trend (P = .055) for altered collagen-to-elastin ratio in a region occupying more than the one (outer) half of the media of the experimental group animals. No changes were observed in the control group.

CONCLUSIONS

The findings of the present study demonstrated that interruption of vasa vasorum flow led to an acute decrease in the distensibility of the ascending aorta. Moreover, structural changes of the aortic wall and further deterioration of the elastic properties of the aorta occurred 15 days after vasa vasorum removal.

Retrograde nontransseptal balloon mitral valvuloplasty using a modified Inoue balloon catheter

Retrograde nontransseptal balloon mitral valvuloplasty, a method developed in our institution for the treatment of symptomatic mitral stenosis, avoids transseptal catheterization. Until recently, the self-positioning Inoue balloon catheter, unlike all other commercially available balloon catheters, had not been employed in this nontransseptal technique due to the short length of its catheter shaft. To employ a self-positioning balloon in retrograde nontransseptal balloon mitral valvuloplasty, we modified the Inoue device by extension of the catheter shaft. After retrograde nontransseptal left atrial catheterization using a steerable cardiac catheter, the modified Inoue balloon catheter was inserted through the femoral artery and advanced to the mitral valve retrogradely. Valvuloplasty was performed in 20 patients, with a successful result achieved in all. The modified Inoue balloon catheter was easy to use in retrograde nontransseptal balloon mitral valvuloplasty and showed excellent stability during inflation. Mean mitral valve area increased from 1.0 +/- 0.29 to 2.23 +/- 0.64 cm2 (P < 0.001) and mean transmitral gradient decreased from 11.4 +/- 6 to 4.3 +/- 2.1 mm Hg (P < 0.001). No major or minor complications were observed. Retrograde nontransseptal balloon mitral valvuloplasty using a modified Inoue balloon catheter is a feasible and effective technique for the treatment of symptomatic mitral stenosis. It appears to combine the advantages of avoiding transseptal catheterization with the advantages of this balloon's special configuration.

Distensibility of the ascending aorta in coronary artery disease and changes after nifedipine administration

To study the effect of nifedipine on aortic distensibility in patients with coronary artery disease, ascending aorta distensibility was measured before and 10 min after 10 mg of nifedipine was given sublingually in 13 patients with coronary artery disease and 12 control subjects. Aortic distensibility was calculated as a function of changes in the aortic diameter and pulse pressure. Aortic diameters were measured by echocardiography and aortic pressures were measured directly by catheterization of the ascending aorta. At baseline, aortic distensibility was lower in patients with coronary artery disease compared with control (0.922 +/- 0.367 vs 2.456 +/- 0.588 10(-6).cm2.dyn-1, respectively, p < 0.001). After nifedipine administration, aortic distensibility increased significantly both in normal subjects (by 0.812 +/- 0.316 10(-6).cm2.dyn-1-36.5 +/- 19 percent; p < 0.001) and in patients with coronary artery disease (by 0.296 +/- 0.203 10(-6).cm2.dyn-1-36.6 +/- 28.2 percent; p < 0.001). These results indicate that nifedipine administration increases aortic distensibility in both normal subjects and patients with coronary artery disease.

Retrograde non-transseptal balloon mitral valvuloplasty--an initial experience

Eleven patients with symptomatic isolated non-calcific mitral stenosis were treated with retrograde nontransseptal balloon mitral valvuloplasty. This new technique utilizes a specifically designed steerable catheter to enter the left atrium retrogradely via the left ventricle thus avoiding transseptal puncture, an essential step in other methods of balloon mitral valvuloplasty. Technical success was obtained in ten (91%) patients. Mitral valve area increased from 0.8 +/- 0.2 to 1.8 +/- 0.4 cm2 and the transmitral gradient decreased from 23.9 +/- 7.7 to 8.2 +/- 2.8 mmHg. There were no major complications such as cardiac perforation, embolic events, cardiac tamponade or severe mitral regurgitation. This early experience, the first outside Greece (centre of origin) indicates that retrograde nontransseptal balloon mitral valvuloplasty is a simple, effective and safe technique with results comparable with other techniques of mitral balloon dilatation which require transseptal catheterisation. Further experience involving multicenteric trials, is required to determine the overall efficacy of this technique for percutaneous balloon mitral valvuloplasty.

Retrograde nontransseptal balloon mitral valvuloplasty. Immediate results and long-term follow-up

BACKGROUND

Percutaneous retrograde nontransseptal balloon mitral valvuloplasty is a new technique developed in our institution for opening a stenotic mitral valve. This technique is based on a new, externally steerable cardiac catheter that enters the left atrium retrogradely via the left ventricle.

METHODS AND RESULTS

The technique was used in 86 consecutive patients (18 men and 68 women; mean age, 51 +/- 11 years). Dilatation of the stenotic mitral valve was achieved in 85 of the 86 patients. After the procedure, mitral valve area increased from 0.92 +/- 0.22 to 2.14 +/- 0.54 cm2 and transmitral gradient decreased from 16 +/- 6 to 5 +/- 2 mm Hg. Major complications, such as cardiac performation, embolic events, or death, were not encountered. Severe mitral regurgitation (greater than 2+) developed in three patients (3.5%). In two patients (2.4%), there was major injury of the femoral artery. The maintenance of the initial improvement was similar to that found in studies that used transseptal techniques. The restenosis rate during the 2-year follow-up was 15.4%.

CONCLUSIONS

The immediate and long-term findings of this study indicate that retrograde percutaneous nontransseptal balloon mitral valvuloplasty is an effective and safe procedure with an acceptable major complication rate. Moreover, this new technique has the advantage that it does not involve puncture and dilatation of the interatrial septum, although it may occasionally lead to arterial damage. Further studies will show whether it may really be considered as an alternative method or method of choice for percutaneous balloon mitral valvuloplasty.