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Biomedical subjects

S R Ramee

Publications and source records attributed to S R Ramee.

84 records · Page 5Linked to original sources
PubMed1990

Percutaneous coronary angioscopy: methods, findings, and therapeutic implications.

The development and clinical implementation of percutaneous coronary angioscopy represents an engineering triumph, blending the newest technologies and materials in the field of fiberoptics with the most advanced techniques of balloon angioplasty catheter materials and construction. Current devices provide a safe method for acquiring excellent quality images of the coronary arteries. This is due to major advances in catheter alignment techniques allowing coaxial positioning of the angioscope in the relatively tortuous coronary arteries. Additional development is needed to further refine the degree of operator control over the field of view, which would also reduce procedure duration. The percutaneous coronary angioscope is currently a functional device for investigators attempting to correlate the morphology of atherosclerotic lesions and clinical coronary artery disease. Confirmation of the value of the angioscope as a clinically useful device for routine application in the diagnosis and management of cardiovascular disease will depend upon the results of further studies.

Angioplasty, Balloon, Coronary↗
PubMed1990

Laser angioplasty in coronary artery disease.

At the present time all laser coronary angioplasty systems in use are investigational devices awaiting FDA approval. Preliminary results in human trials of several coronary laser angioplasty systems have been reported and appear encouraging. The technological achievement of delivering laser energy to the coronary circulation and opening occluded arteries has been accomplished. The much more difficult question of determining which patients, if any, should be offered this very expensive technology remains to be answered.

Coronary Disease↗
PubMed1989

Repeat balloon aortic valvuloplasty for aortic valve restenosis.

Effective balloon aortic valvuloplasty (BAV) is limited restenosis. After aortic valve restenosis six patients underwent repeat BAV. In spite of the use of larger balloons there was a trend toward a less satisfactory result after repeat BAV (0.98 +/- .26 cm2 vs. 1.2 +/- .26 cm2), which did not reach statistical significance, P = .14. Mortality of the patients at 6 months was 50%. Repeat BAV may be less efficacious than the original procedure.

Aged↗
PubMed1988

Laser angioplasty: an atherosclerotic swine model.

Rapid production of occlusive, atherosclerotic iliac artery lesions was achieved in 25 of 27 (93%) Yucatan miniature swine, using a combination of high cholesterol diet and mechanical endothelial denudation. Animals were fed a diet with 2% of their calories as raw cholesterol 2 weeks prior to balloon denudation of iliac arteries, which resulted in atherosclerotic lesions within 8 weeks. Early after denudation we have demonstrated total occlusion of arteries by fibrin thrombi, which in time organize and ultimately result in fibrotic occlusive disease. The arterial walls and intima show varying degrees of foam cell infiltration with destruction of the internal elastic lamina and calcification. Totally occluded lesions show fibrointimal proliferation, fibrosis, and multiluminal channels, which are probably secondary to organized thrombus. Our model of occlusive iliac artery disease involving vessels of 1 to 3 mm in diameter allows the development of catheter systems suitable for use in human peripheral and coronary arteries. This model is useful for the study of angioplasty, whether mechanical, balloon, or laser-mediated.

Angioplasty, Balloon↗
PubMed1987

Hormonal and renal responses to converting enzyme inhibition during maximal exercise.

The role of angiotensin II in the hormonal and renal responses to maximal exercise was investigated by using the angiotensin-converting enzyme inhibitor captopril. Nine male subjects performed a standardized maximal treadmill test with and without acute captopril treatment (25 mg orally). At rest, captopril elevated plasma renin activity and lowered aldosterone levels. With maximal exercise, captopril treatment reduced the increase in mean arterial blood pressure by 8 mmHg and the increase in plasma renin activity by 3.0 ng ANG I.ml-1.h-1. The responses of adrenocorticotropin (ACTH), cortisol, and vasopressin to maximal exercise were not altered by captopril treatment. Although aldosterone levels were reduced at rest with captopril, during maximal exercise no difference was noted between treatments. Captopril treatment had no effects on the renal handling of salts or water during exercise. In conclusion, angiotensin II plays a role in the increase in mean blood pressure during maximal exercise in normal subjects but has no effect on the exercise responses of ACTH, vasopressin, and aldosterone or on the renal handling of salts and water.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Tolerance of normal aorta to oversized dual balloon valvuloplasty. Observations in a swine model: technical note.

The damage threshold during aortic valvuloplasty was determined in 12 normal swine subjected to inflation of oversized dual balloons. Catheters with combined balloon diameters of 1.2-2.0 times the aortic annulus were selected. Following completion of the procedure, the animals were sacrificed and examined for pathology. With combined balloon diameters less than or equal to 1.7 times the aortic annulus, there was no gross or microscopic damage. In animals with combined diameters equal to 2 times the aortic annulus, there was rupture of the aorta. This data provides further basis for the selection of catheter sizes in dual balloon aortic valvuloplasty.

Angioplasty, Balloon↗
PubMedDate not supplied

Intracoronary and aortic root myocardial contrast echocardiography: the effect of route, dose, and pharmacologic coronary vasodilation.

Myocardial contrast echocardiography is useful for the assessment of myocardial perfusion but has required direct intracoronary injections. Aortic root myocardial contrast echocardiography has the potential advantage of allowing simultaneous assessment of multiple perfusion beds, as well as evaluating competitive and collateral flows. This study assessed the safety and efficacy of intracoronary and aortic root injections of sonicated 5% human serum albumin (Albunex) with and without concomitant coronary vasodilation. Without vasodilation, 72% of intracoronary injections had optimal myocardial enhancement, compared with 21% of aortic root injections. For individual patients, significant dose-response relationships existed for both intracoronary and aortic root injections, although contrast intensity for a given dose varied between patients. Pharmacologic vasodilation resulted in significant increases in contrast intensity and in the incidence of optimal myocardial contrast after aortic root injections. Aortic root myocardial contrast echocardiography potentially allows the simultaneous assessment of multiple perfusion beds through a route somewhat less invasive than that of direct intracoronary injections.

Adult↗
PubMedDate not supplied

Multicenter trial of the wallstent in the iliac and femoral arteries.

PURPOSE: To report the results of the FDA phase II, multicenter trial of the Wallstent in the iliac and femoral arteries. PATIENTS AND METHODS: Two hundred twenty-five patients entered the trial. Stents were placed in the iliac system in 140 patients and in the femoral system in 90 (five patients required both iliac and femoral stents). Clinical patency was measured over 2 years by means of life-table analysis with use of clinical and hemodynamic data and the Rutherford scale. Angiographic patency was measured at 6 months. RESULTS: In the iliac system the primary clinical patency was 81% at 1 year and was 71% at 2 years. The secondary clinical patency was 91% and 86%, respectively. The 6-month angiographic patency was 93%. In the femoral system the primary clinical patency was 61% at 1 year and 49% at 2 years. The secondary patency was 84% and 72%, respectively. The 6-month angiographic patency was 80%. CONCLUSIONS: The results are similar to those with the Palmaz stent in the iliac system and with angioplasty alone in the iliac and femoral systems.

Adult↗
PubMedDate not supplied

Presence of severe intimal thickening by intravascular ultrasonography predicts cardiac events in cardiac allograft vasculopathy.

BACKGROUND: The clinical utility of intimal hyperplasia detected by intravascular ultrasonography in predicting cardiac events in heart transplant recipients with cardiac allograft vasculopathy has not been previously investigated. METHODS: Intravascular ultrasonographic examination of 74 consecutive heart transplant recipients, including 62 men and 12 women with a mean age of 51 +/- 10 years (range 22 to 68 years), was performed at the time of annual angiography. Two groups of study patients were identified: group I consisted of patients with minimal, mild, or moderate intimal thickness by intravascular ultrasonography, whereas group II patients had severe intimal thickness. RESULTS: Patient characteristics were similar in both groups except for higher serum triglycerides (220 +/- 95 versus 165 +/- 79 mg/dl), more advanced donor age (28 +/- 11 versus 23 +/- 6 years) and greater duration of follow-up after transplantation (3.3 +/- 1.4 versus 1.8 +/- 1.2 years) in group II patients with severe intimal thickening (p < 0.01). Cardiac events were defined as the occurrence of sudden death, myocardial infarction, or the need for coronary revascularization via percutaneous or surgical intervention. One cardiac event occurred in group I patients (sudden death), whereas seven events were noted in the group II patients (p = 0.006). Cardiac events in the group of patients with severe intimal thickening included four patients with sudden cardiac death and three patients who underwent percutaneous revascularization procedures involving directional coronary atherectomy. Angiograms were normal in 62% of patients who had cardiac events. CONCLUSIONS: This study represents one of the first reports that provides evidence that severe intimal hyperplasia predicts the development of cardiac events even in the presence of a normal coronary angiogram.

Adult↗
PubMedDate not supplied

Directional coronary atherectomy in heart transplant recipients.

Cardiac allograft vasculopathy is one of the most common obstacles to the long-term survival of heart transplant recipients. Percutaneous transluminal angioplasty has been used as a palliative treatment for discrete lesions caused by this disease, but it is often complicated by restenosis. This report describes two cases in which directional coronary atherectomy was used to treat the discrete lesions and explores the possible advantages of this intervention in lieu of the traditional approach. Our results suggest that directional coronary atherectomy is a feasible alternative to conventional balloon angioplasty.

Atherectomy, Coronary↗