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.

Impaired compensatory coronary artery enlargement in atherosclerosis contributes to the development of coronary artery stenosis in diabetic patients. An in vivo intravascular ultrasound study

AIMS

Coronary arteries affected by atherosclerosis undergo focal compensatory enlargement, which can be detected by intracoronary ultrasound but not by angiography. Diabetic patients when compared with non-diabetics have a more accelerated progression of coronary artery disease and a more diffuse narrowing of the coronary arteries. Intracoronary ultrasound can clarify if this is due to less compensatory coronary artery enlargement as a response to atherosclerosis.

METHODS AND RESULTS

Ten non-diabetic and 15 diabetic patients with coronary artery disease, with angiographically determined one- or two-vessel disease, underwent intracoronary ultrasound examination of the non-stenotic coronary artery. Forty-five sites with luminal stenosis, detected by intracoronary ultrasound, were analysed (15 in non-diabetics, 30 in diabetics). Vessel and lumen area, atherosclerotic plaque area and plaque composition were evaluated. Vessel area was also measured proximal and distal to the healthy segment. In the diabetic patients, there was less vessel area increase from the proximal healthy segment into the atherosclerotic segment than in the non-diabetic patients (99% separate-variance confidence intervals for differences between diabetics' and non-diabetics' means = 0.29 mm2, 2.71 mm2). The proximal plaque free vessel area, the atherosclerotic plaque area and plaque composition were similar between the two groups.

CONCLUSION

Diabetics with atherosclerosis have less compensatory coronary artery enlargement than non-diabetics. This may explain the diffuse and accelerated course of coronary artery disease in these patients.

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.

Echocardiographic features of left atrium in elite male athletes

In athletes, an increase in left atrial volumes is observed, associated with decreased atrial contractile performance and enhanced conduit function.

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.

Left atrial mechanical function in the healthy elderly: new insights from a combined assessment of changes in atrial volume and transmitral flow velocity

To assess left atrial mechanical function in the elderly, 35 old (age > 70 years) and 18 sex-matched young (age < 50 years) healthy subjects were studied. Transmitral flow velocities were recorded with pulsed Doppler echocardiography. Left atrial volumes were measured echocardiographically at mitral valve opening (maximal) and closure (minimal) and at onset of atrial systole (P wave of the electrocardiogram) according to the biplane area-length method. Left atrial passive emptying was assessed with the passive emptying volume (maximal-volume at onset of atrial systole) and fraction (passive emptying volume/maximal). Left atrial active emptying was assessed with the active emptying volume (volume at onset of atrial systole-minimal) and fraction (active emptying volume/volume at onset of atrial systole) and with left atrial ejection force = 0.5.blood density.volume at onset of atrial systole.active emptying fraction.(A velocity)2/A integral. Left atrial volumes were greater in old compared with young subjects (maximal: 31 +/- 10 cm3/m2 vs 24 +/- 8 cm3/m2, p = 0.02; at onset of atrial systole: 23 +/- 8 cm3/m2 vs 15 +/- 5 cm3/m2, p = 0.0002; minimal: 13 +/- 5 cm3/m2 vs 9 +/- 4 cm3/m2, p = 0.001). Passive emptying volume and fraction were lower (7.8 +/- 1.7 cm3/m2 vs 9.2 +/- 3.2 cm3/m2 [p = 0.04] and 26.4% +/- 9.8% vs 37.9% +/- 11.2% [p = 0.003], respectively), whereas atrial ejection force and active emptying volume were greater in old compared with young subjects (6.8 +/- 3.3 kdynes/m2 vs 4.2 +/- 2.8 kdynes/m2 [p = 0.007] and 9.2 +/- 4.1 cm3/m2 vs 5.7 +/- 2.9 cm3/m2 [p = 0.002], respectively). The active emptying fraction was similar in the two groups (39.7% +/- 11% vs 38.4% +/- 13%; difference not significant). Thus advanced age is associated with depressed left atrial passive emptying function and increased left atrial volume. Left atrial dilation contributes to an increase in atrial ejection force and the amount of blood ejected during left atrial systole and may represent an important compensatory mechanism in this age population.

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.