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At least 919 records · Page 51Linked to original sources
PubMed1982

Noninvasive estimation of central aortic pressure using the oscillometric method for analyzing systemic artery pulsatile blood flow: comparative study of indirect systolic, diastolic, and mean brachial artery pressure with simultaneous direct ascending aortic pressure measurements.

Brachial artery pressures determined by the oscillometric method were compared with simultaneous central aortic (Ao) pressure measurements in 30 patients undergoing cardiac catheterization. Three simultaneous oscillometric and central Ao pressure readings were obtained in each patient. Central Ao pressures ranged widely for systolic (SP) (98 to 177 mm Hg), diastolic (DP) (41 to 97 mm Hg), and mean (MP) (60 to 120 mm Hg) pressure values. The mean percent errors (pressure difference divided by central Ao pressure) and "within subject" standard deviation were 1% and 3% for SP, 2% and 4% for DP, and -3% and 7% for MP. The percent error in oscillometric SP and DP estimates was not significantly influenced by cardiac index, systemic vascular resistance, heart rate, body surface area, or left ventricular ejection fraction. The oscillometric method provides accurate, reproducible, and convenient estimates of central Ao SP and DP and may be particularly useful when indirect blood pressure measurements are required for the noninvasive assessment of left ventricular function in patients without aortic stenosis.

Adult↗
PubMed2005

First clinical experience with the Incor left ventricular assist device.

BACKGROUND: The Incor (Berlin Heart AG, Germany) is a small (200 g), implantable, magnetically accentuated axial flow pump (non-pulsatile flow) designed to support the left ventricle for extended periods of time. We report on the first single-center clinical experience with this device. METHODS: The Incor was studied in 15 consecutive patients (10 men, 5 women), 24 to 59 years of age. Underlying heart disease was end-stage ischemic heart disease (n = 5), acute myocardial infarction (n = 4), dilated cardiomyopathy (n = 3), acute myocarditis (n = 2) and Chagas disease (n = 1). All patients were in New York Heart Association (NYHA) Class IV heart failure. Four patients had prior open heart surgery. Implantation via cannulation of the left ventricular apex and the ascending aorta was elective in 6 patients and on an emergency basis in 9. RESULTS: No early bleeding complications were seen, but late bleeding occurred in 4 patients. Minor cerebral thromboembolic events with transient neurologic symptoms occurred in 3 patients; severe stroke had to be treated in 1 patient. Systemic emboli were seen in 2 patients. Thrombus-related pump dysfunction was suspected in 3 patients, and managed by intensifying anti-coagulation. Five patients were successfully transplanted after a support interval of 90 to 156 days; 1 patient could be weaned from the system after 171 days. Six patients died during support, 9 to 63 days after device implantation. The remaining 3 patients are still under support, with excellent quality of life. CONCLUSIONS: The Incor is a left ventricular assist device (LVAD) with transplant and adverse event rates comparable to those of other modern ventricular support devices. Its advantages include the small pump chamber, the virtual absence of device-related infections, and the extraordinary convenience during implantation and explantation.

Adult↗
PubMed1998

Platelet adhesion and aggregation in pulsatile shear flow: effects of red blood cells.

An in vitro test system was developed to examine the effects of red blood cells (RBC) on shear-induced platelet adhesion (SIPAD) and platelet aggregation (SIPAG). Suspensions of human platelets labeled with Mepacrine and suspended in citrated plasma were exposed to single, continuous or repetitive (120-300x) one second shear stress pulses of varying amplitude (15-100 dyn/cm2) in a cone-plate viscometer in the presence or absence of fresh, untreated (intact) RBC or glutaraldehyde (GLA)-fixed, rigid, adenosine diphosphate (ADP)-depleted (GLA)-RBC. SIPAG was expressed as percent loss of single platelets. SIPAD was assessed by measuring the amount of Mepacrine-related fluorescent material remaining on glass disks in the plate of the viscometer after washing with EDTA-saline to remove platelet aggregates. Intact RBC were twice as effective as GLA-RBC in potentiating SIPAG at all shear stress levels. Potentiation of SIPAD by intact RBC was markedly less than that observed with GLA-RBC at stresses below 50 dyn/cm2. These findings are consistent with the concept that while both physical and chemical (ADP) mechanisms are substantially involved in potentiation by RBC of SIPAG, RBC support SIPAD largely by enhancement of platelet transport from the bulk flow to the bounding surfaces. The findings also indicate that it is feasible to assess SIPAD and SIPAG in the same flow system simultaneously. A less complicated version of the method described here should prove useful in the evaluation of patients with platelet functional disorders, and in the evaluation and monitoring of antiplatelet agents.

Blood Platelets↗
PubMed2003

A new concept for covered stent protected carotid angioplasty: an ex vivo study.

OBJECTIVE: To determine the efficacy of a covered stent prototype designed for protected carotid angioplasty to reduce cerebral embolization. MATERIAL AND METHOD: The covered stent tested is made of nitinol, coated with a polyurethane membrane (MembraX trade mark; porous size 80 micro m). In a bench-top model (flow-rate 650 ml/min, pulsatile flow [dicrote] 123 Pulses/min, pressure 100/60 mm Hg [mean pressure 80 mmHg]) with inserted human carotid (n = 6) stent implantation was performed (8/32 mm). Passed particles (mg) were determined in the effluent of a 100 micro m filter prior to intervention, after stent deployment and after final dilation (5 mm). RESULTS: When stenting carotid arteries obtained from human cadavers, the highest rate of particle embolization was measured while crossing the lesion with the delivery device (6,8 mg; for all p < 0,05), embolization after additional balloon angioplasty and particle rates measured in the effluent filter prior covered stent placement were significantly lower (3,8 mg; p < 0,05). Branches of the external carotid artery remained patent in all cases. CONCLUSIONS: The introduced concept of covered stent protected carotid angioplasty with the MembraX trade mark prototype has proven promising results for low cerebral embolization rates ex vivo. Further evaluations using an animal model and a miniaturization of the delivery device are warranted prior to human use.

Adult↗