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Biomedical subjects

J A Strom

Publications and source records attributed to J A Strom.

At least 19 recordsLinked to original sources
PubMed2004

Heart failure in Parkinson's disease: analysis of the United States medicare current beneficiary survey.

OBJECTIVE: We sought to examine the prevalence of heart failure in elderly PD versus non-PD patients using a national sample of Medicare beneficiaries in the United States. SCOPE: The prevalence of heart failure in elderly PD patients was 2.27 times that of non-PD patients (19.4% versus 8.7%, 95% CI = 1.43-3.60, p 0.0005), and remained twice as high after excluding patients with stroke and possible vascular parkinsonism. CONCLUSIONS: In this cross-sectional study of a national Medicare database, heart failure occurred twice as frequently in elderly PD patients as in non-PD patients. Prospective studies are warranted to verify these findings.

Aged↗
PubMed2001

Jet eccentricity: a misleading source of agreement between Doppler/catheter pressure gradients in aortic stenosis.

Characterization of the severity of aortic stenosis relies on accurate measurement of the pressure gradient across the valve and the valve area. Pressure gradients measured by Doppler ultrasound based on the clinical form of the Bernoulli equation often overestimate pressure gradients by catheter as the result of pressure recovery. Doppler techniques measure the velocity of the vena contracta of the stenotic jet. This corresponds to the maximal pressure gradient and the minimal effective valve area. Pressure recovery can be characterized by analysis of the spread of the stenotic jet downstream of the valve as it fills the aorta and should be influenced by the shape of the velocity profile of the decaying jet. In this study, we addressed the hypothesis that the site of complete pressure recovery (the point at which the jet fully expands to the size of the aorta), the effective valve area, and the maximal pressure gradient are affected by jet eccentricity. To accomplish this, we developed a computational model of aortic stenosis that provides detailed velocity and pressure information in the vicinity of the valve. The results show that the width of the eccentric wall jet decreased and maximal velocity increased with greater jet eccentricity. Furthermore, for a constant anatomic area, the effective valve area decreased, the distance to complete pressure recovery increased, and the maximal pressure gradient increased with the degree of eccentricity. Failure to take this into account could fortuitously drive Doppler and catheter measurements toward agreement because the distal pressure sensor will not record the fully recovered pressure. Therefore the pressure gradient across a stenotic valve depends on jet eccentricity. The spread of the wall jet after attachment must be characterized to develop a robust method for the prediction of pressure recovery.

Aortic Valve↗
PubMed2001

One-year study of felodipine or placebo for stage 1 isolated systolic hypertension.

Asubstantial number of older hypertensive patients have stage 1 isolated systolic hypertension (systolic blood pressure between 140 and 159 mm Hg and diastolic blood pressure <90 mm Hg), but there are currently no data showing that drug treatment is effective, safe, and/or beneficial. To compare the effects of active treatment compared with placebo on blood pressure, left ventricular hypertrophy, and quality of life among older stage 1 isolated systolic hypertensive patients, a randomized, double-blind, parallel-group, multicenter clinical trial comparing felodipine (2.5, 5, or 10 mg once daily) and matching placebo was performed in 171 patients (49% male, average age 66+/-7 years, with 49% white and 30% Hispanic) with a baseline blood pressure of 149+/-7/83+/-6 mm Hg. During 52 weeks of treatment, patients randomized to active treatment achieved significantly lower blood pressures (137.0+/-11.7/80.2+/-7.6 mm Hg for extended-release felodipine versus 147.5+/-16.0/83.5+/-9.7 mm Hg for placebo, P<0.01 for each), a reduced incidence of left ventricular hypertrophy (7% for extended release felodipine versus 24% for placebo, P<0.04), and improved quality of life (change in Psychological General Well-Being index, 3.0+/-6.8 for extended-release felodipine versus -0.8+/-10.3 for placebo, P<0.01) versus baseline. There were no clinically significant differences between treatments in tolerability or adverse effects. Stage 1 isolated systolic hypertension can be effectively and safely treated pharmacologically. Treatment reduced progression to the higher stages of hypertension, reduced the incidence of left ventricular hypertrophy, and improved an overall measure of the quality of life. Larger and longer studies will be needed to document any long-term reduction in cardiovascular event rates associated with treating stage 1 systolic hypertension.

Aged↗
PubMed2000

Vasoseal after intra-aortic balloon pump removal: a pilot study.

Vascular complications after removal of an intra-aortic balloon pump (IABP) have been reported to occur in up to 15% of patients. Vasoseal, a vascular hemostasis device (VHD), has been shown to be safe and effective in rapidly achieving hemostasis after a cardiac catheterization or percutaneous coronary intervention. We propose that similar results can be obtained with the VHD when removing an IABP. However, it is necessary to first gain first the experience of deploying the VHD without insertion of a guidewire. We studied 10 patients in whom Vasoseal was utilized after an IABP was removed. The primary endpoint was a composite of major or minor bleeding, infection, and any vascular complication at 7 days. The time to achieve hemostasis was also assessed. There was not a single episode of bleeding, infection, or vascular injury at 7 days. The time to hemostasis ranged between 8 and 17 min (mean, 12.9 min). This VHD can be utilized safely and efficaciously when removing an IABP.

Adult↗
PubMed2000

Drip and ship: a new strategy for the treatment of acute coronary syndromes.

Glycoprotein (GP) IIb/IIIa inhibitors block the final common pathway of platelet aggregation by preventing fibrinogen from binding to the GP IIb/IIIa platelet receptor. In patients with unstable angina (UA) or a non-Q wave myocardial infarction (NQWMI), including those with UA refractory to medical therapy, these agents decrease the risk of death, myocardial infarction (MI), and recurrent ischemia. Most patients with acute coronary syndromes are managed in hospitals without on-site angioplasty capabilities and often require transfer for an interventional procedure. We propose that GP IIb/IIIa inhibitors can be safely initiated at the referring hospital. We studied 20 patients with UA/NQWMI in whom therapy with a GP IIb/IIIa inhibitor, in addition to standard medical therapy, was initiated prior to transfer for an urgent percutaneous coronary intervention (PCI) ("drip and ship"). The primary end point was a composite of death, MI, and recurrent ischemia at 30 days. Twelve patients were treated with abciximab, 5 patients were treated with tirofiban, and 3 patients initially treated with tirofiban were converted to abciximab. Procedural success occurred in 33 out of 36 (92%) lesions and 18 out of 20 (90%) patients. At 30 days, 4 out of 20 (20%) patients had recurrent ischemia. The PTCA sites were widely patent in the 3 patients who underwent repeat angiography. The fourth patient had an unsuccessful PCI and was referred for coronary artery bypass surgery. There were no MIs or deaths. Patients who require transfer for an urgent PCI can be managed safely and efficaciously by initiating a GP IIb/IIIa inhibitor, in addition to standard medical therapy, prior to transfer.

Abciximab↗
PubMed2000

Simultaneous Doppler/catheter measurements of pressure gradients in aortic valve disease: a correction to the Bernoulli equation based on velocity decay in the stenotic jet.

BACKGROUND AND AIM OF THE STUDY: Characterization of the severity of a stenotic aortic valve relies on accurate measurement of the pressure drop across the valve. A simplified form of the Bernoulli equation has been used to estimate pressure drops using Doppler ultrasound, but these measurements often overestimate gold standard measurements performed during cardiac catheterization. Sources of discrepancy between the Doppler and catheter measurements have been identified, but no method has been developed to fully reconcile the two techniques. METHODS: In this study we developed a correction to the clinical form of the Bernoulli equation based on receiving chamber geometry and turbulent jet profiles. The theoretical treatment of the mechanical energy balance, assuming a shape to the stenotic jet profile is described, and the assumptions in our model are discussed. The use of the model was then demonstrated in an in vivo clinical study in which simultaneous Doppler and catheter data were obtained. RESULTS: Discrepancies between Doppler and catheter are shown to be a function of the predicted pressure recovery location based on our assumed profile. There exists a distance of about 8.67 valve radii downstream where agreement in peak pressure gradients is theoretically achieved. CONCLUSION: The results demonstrate the ability to characterize pressure recovery distal to the valve. Our approach, to substitute a more appropriate velocity profile into the mechanical energy balance, unifies geometric parameters and the physics of turbulent jet flow in an equation involving quantities already routinely measured in an echocardiographic examination of aortic stenosis. This allows for both the maximal and recovered pressure gradient to be obtained from the Doppler data. These results have implications for optimal pressure sensor placement for the assessment of aortic stenosis and also for the evaluation of prosthetic heart valves in vitro.

Aortic Valve↗
PubMed1999

Inter-laboratory comparisons: approaching a new standard for prosthetic heart valve testing in vitro.

Current standards governing the evaluation of prosthetic heart valve designs have come under scrutiny. Generally, standards require measurements of pressure drops and regurgitant flow. While this information is important in the characterization of valve performance, these standards are both insufficient and ambiguous. Their insufficiency is due to the fact that they do not cover issues related to thrombosis and structural damage, and their ambiguity is demonstrated by the fact that different pulse duplicators will produce different results for nominally the same set of conditions. While the insufficiency of the current standards has recently been addressed, the ambiguity has not been addressed in a systematic way except for one particular study involving two pulse duplicator systems. This paper explores physical sources for disagreement in pressure and flow measurements between pulse duplicators, and suggests ways to account for them. By considering these physical phenomena, standards can be developed for testing chambers that improve similarity between systems. This should not compromise innovation in the design of new pulse duplicators, which may be necessary to address additional concerns besides the pressure and flow characteristics of the valve.

Heart Valve Prosthesis↗
PubMed1997

Improved Doppler echocardiographic assessment of the left atrial appendage by peripheral vein injection of sonicated albumin microbubbles.

We evaluated the usefulness of peripherally injected sonicated albumin microbubbles in transesophageal echo-Doppler cardiographic assessment of the left atrial appendage in 19 patients (age 61 +/- 19 [range 21 to 86] years; 12 [63%] women). Multiplane transesophageal echocardiography was performed before and after intravenous injection of sonicated albumin, and the left atrial appendage image and Doppler flow signal quality were assessed by a grading system of 0 to 3+ (0 = poor, 1 + = adequate, 2+ = good, and 3+ = excellent). Microbubbles appeared in the left atrium in 15 (79%) of 19 patients and completely opacified the left atrial appendage in 7 (37%) of 19 patients. Left atrial appendage maximal and minimal areas by planimetry were similar before and after contrast injection, although image quality improved in 13 (68%) of 19 patients (echocardiographic grade 1.8 +/- 0.6 vs 2.6 +/- 0.5, p< 0.001). Similarly, left atrial appendage peak emptying and peak filling Doppler flow velocities did not change before and after contrast injection, although Doppler flow signal quality improved in 12 (63%) of 19 patients (Doppler grade 1.6 +/- 0.5 vs 2.1 +/- 0.8, p < 0.05). Overall, contrast injection improved left atrial appendage echocardiographic or Doppler quality in 16 (84%) of 19 patients. Thus peripheral vein injection of sonicated albumin microbubbles can improve the assessment of left atrial appendage structure and function by transesophageal echocardiography.

Albumins↗
PubMed1996

Impact of single use versus reuse of cellulose dialyzers on clinical parameters and indices of biocompatibility.

Hemodialysis with reprocessed dialyzers has been associated with an increased mortality in patients on chronic dialysis, but the causes for this increased mortality have not been identified thus far. The aim of this study was to compare the qualitative and/or quantitative differences in activation of cellular and plasma elements, intradialytic signs and symptoms, adequacy of dialysis, and serum biochemistry and hematology in patients dialyzed with new or reprocessed cellulose dialyzers. This study measured the plasma levels and production of interleukin-1 receptor antagonist (IL-1Ra) by peripheral blood mononuclear cells (PBMC), indices of cytokine synthesis; plasma C3a levels, an index of complement activation; plasma levels of lipopolysaccharide binding protein (LBP), an acute phase reactant; and plasma levels of bactericidal-permeability increasing factor (BPI), a neutrophil primary granule protein, in 37 patients on chronic hemodialysis with glutaraldehyde and bleach-reprocessed cellulose dialyzers after random assignment to 12 wk of dialysis with new (single use) or reprocessed (reuse) cellulose dialyzers. These indices were studied before dialysis, 15 min after the start of dialysis, and at the conclusion of dialysis in both groups. Intradialytic clinical symptoms and signs, urea reduction ratios, monthly blood chemistry, and hematology were also studied during the 12-wk period. Before randomization, clinical and laboratory characteristics and IL-1Ra production by PBMC were similar in the two groups. During the 12-wk study, the mean number of dialyzer reuses was 7 +/- 1 in the reuse group and there were no breaks in protocol in the single-use group. At the end of the study, plasma levels of IL-1Ra, cell content and production of IL-1Ra by unstimulated, endotoxin-stimulated, and lgG-stimulated PBMC among patients assigned to reuse were not significantly different from those in the single-use group either before dialysis, at 15 min, or at the conclusion of dialysis. Similarly, plasma levels of C3a, LBP, and BPl were not significantly different between groups at any of the three time points. During the 12-wk study, none of the patients in either arm of the study experienced chills, rigors, or fever, and there were no differences in the number of episodes of symptomatic hypotension in patients on reused dialyzers (11 +/- 3) compared with patients on single-use dialyzers (8 +/- 2). The mean monthly urea reduction ratio during the 3 months of the study was 63 +/- 2% and 65 +/- 2% for reuse and single-use dialyzers, respectively (not significant). Similarly, the hematocrit, white blood cell count, serum calcium, phosphorus, cholesterol, triglycerides, total protein, and albumin levels were also not significantly different between the two groups at the end of the 12-wk study period. These results suggest that the reprocessing of cellulose dialyzers with glutaraldehyde and bleach does not affect indices of blocompatibility, intradialytic symptoms and signs, adequacy of dialysis, or serum biochemistry and hematology.

Acute-Phase Proteins↗
PubMed1994

A ten-year study of the Ionescu-Shiley low-profile bioprosthetic heart valve.

Seven hundred and eight adults (age > or = 16 years) with isolated aortic (n = 433) or mitral (n = 275) Ionescu-Shiley Low-Profile (ISLP) pericardial valves were followed at 14 implanting centres in Canada, the United Kingdom, and the United States for a mean of 6.7 years, providing 4,729 patient-years of clinical data. The operative mortality rate was 3.0% for aortic valve replacement (AVR) and 5.5% for mitral valve replacement (MVR) (p = ns). Actuarial patient survival following AVR at 5 years was 81.6%, and 62.9% at 10 years; for MVR patients it was 78.1% at 5 years and 59.6% at 10 years. The ISLP valve appears to have durability comparable to other contemporary bioprosthetic valves. For aortic prostheses, the freedom from structural deterioration was 96.5% at 5 years and 73.7% at 10 years, and 89.7% at 5 years and 62.4% at 10 years for mitral prostheses. Structural deterioration was significantly more frequent following MVR than after AVR (p < 0.05). Structural deterioration was the principal cause for reoperation, but sudden deterioration precluding safe reoperation was not a dominant feature of this series. The ISLP valve appeared to engender more thrombo-embolic events than would be anticipated from earlier studies of pericardial bioprostheses, but was indistinguishable from other tissue valves in its incidence of other valve-related complications. We conclude that ISLP valves now implanted for 7 years or more are entering a phase of increasing structural deterioration, indicating the need for regular clinical and echocardiographic surveillance, and that long-term anticoagulation should be instituted for relatively minimal indications in these patients.

Adolescent↗
PubMed1994

Plasma levels of IL-1 beta, TNF alpha and their specific inhibitors in undialyzed chronic renal failure, CAPD and hemodialysis patients.

The presence of naturally occurring inhibitors of interleukin-1 (IL-1) and tumor necrosis factor (TNF) in a variety of diseases has been demonstrated. The IL-1 receptor antagonist (IL-1Ra) binds to IL-1 receptors and blocks the activity of IL-1, and a soluble form of the p55 TNF receptor (TNFsRp55) binds and neutralizes TNF. In the present study, plasma levels of IL-1 beta, IL-1Ra, TNF alpha and TNFsRp55 were measured in 29 undialyzed patients with chronic renal failure (CRF), 13 patients on continuous ambulatory peritoneal dialysis (CAPD), 42 patients on chronic hemodialysis (HD) and in 15 healthy controls. Of the 29 patients with CRF, 13 had end-stage renal disease (ESRD, estimated GFR < 10 ml/min). Among health controls, plasma levels of IL-1 beta, IL-1Ra and TNF alpha were at or below the limit of detection of the assay. In undialyzed patients with ESRD, or in patients on CAPD or HD, plasma levels of IL-1 beta were 428 +/- 134 pg/ml, 378 +/- 83 and 352 +/- 43 pg/ml, respectively. Although plasma levels of IL-1 beta in each group of patients were higher than those in healthy controls (< 160 pg/ml), these differences were not statistically significant. In contrast, plasma levels of IL-1Ra in undialyzed patients with ESRD (629 +/- 125 pg/ml, P = 0.03), CAPD (902 +/- 164 pg/ml, P < 0.0001) and HD patients (642 +/- 73 pg/ml, P = 0.004) were significantly higher than those in healthy controls (103 +/- 15).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Comparison of first use and reuse of cuprophan membranes on interleukin-1 receptor antagonist and interleukin-1 beta production by blood mononuclear cells.

The magnitude of the changes in a variety of blood constituents on exposure to the dialysis membrane has been used as an index of "biocompatibility," and dialyzer reuse has been postulated to improve biocompatibility by attenuating these changes. We studied the hemodialysis-induced changes in the in vitro production of interleukin-1 receptor antagonist (IL-1Ra) and interleukin-1 beta (IL-1 beta) by peripheral blood mononuclear cells (PBMCs), and compared the effect of first use and reuse of cuprophan membranes on these changes. Studies were performed during dialysis with first use and third reuse of the same kidney. The cell content and production of IL-1Ra and IL-1 beta by unstimulated and endotoxin- or IgG-stimulated PBMCs were studied just prior to dialysis, and from the afferent and efferent limbs of the blood circuit 15 minutes after the start of dialysis. Interleukin-1 receptor antagonist and IL-1 beta were measured by specific radioimmunoassay and are expressed as picograms per 2.5 x 10(6) PBMCs. Fifteen minutes after the start of dialysis, the number of PBMCs harvested from 10 mL of blood decreased from 19.8 +/- 4.7 x 10(6) predialysis to 14 +/- 3 x 10(6) (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Impaired endothelium-mediated vasodilation in the peripheral vasculature of patients with congestive heart failure.

Impaired endothelial-dependent vasodilation has been demonstrated in two animal models of congestive heart failure and in the coronary circulation of patients with idiopathic dilated cardiomyopathy. To determine whether this impairment contributes to the abnormal peripheral vasomotor tone in patients with congestive heart failure, the local vascular response to intraarterial infusions of graded concentrations (10(-8) M to 10(-5) M) of acetylcholine (an endothelial-dependent vasodilator) and nitroglycerin (a direct-acting vasodilator) was studied in the superficial femoral artery of 19 patients with congestive heart failure (New York Heart Association classes I to IV) and 6 age-matched normal control subjects. The local vascular response was determined from the arterial blood flow velocity pattern obtained by transcutaneous Doppler ultrasonography. Acetylcholine, 10(-5) M, induced a pattern characteristic of vasodilation in all six normal subjects; mean blood flow velocity for the group significantly increased from 11.9 +/- 2.7 to 44.8 +/- 20.9 cm/s (p less than 0.05). In contrast, the same dose of acetylcholine induced a blood flow velocity pattern characteristic of vasodilation in only 4 of the 19 patients with congestive heart failure. Group mean blood flow velocity did not change significantly. Nitroglycerin, 10(-7) M, induced vasodilation in all 6 normal subjects but in only 1 of 19 patients. Nitroglycerin, 10(-5) M, was administered to 10 patients; all 10 demonstrated a pattern characteristic of vasodilation. Thus, acetylcholine-mediated endothelial-dependent vasodilation appears to be impaired in the peripheral vasculature of patients with congestive heart failure. Both endothelial dysfunction and abnormal vascular smooth muscle responsiveness may contribute to abnormal peripheral vasomotor tone.

Acetylcholine↗
PubMed1992

In vitro production of interleukin-1 receptor antagonist in chronic renal failure, CAPD and HD.

Dialysis-related symptoms are believed to be mediated, at least in part, by monocyte/macrophage-derived pro-inflammatory cytokines including interleukin-1 (IL-1) and tumor necrosis factor (TNF). Measuring the production of interleukin-1 receptor antagonist (IL-Ra), a naturally occurring inhibitor of IL-1, opens avenues to study the balance between these two cytokines in patients. We studied the cell content and production of IL-1 beta and IL-Ra by unstimulated and endotoxin- or IgG-stimulated peripheral blood mononuclear cells (PBMC) in undialyzed patients with chronic renal failure (CRF), patients on continuous ambulatory peritoneal dialysis (CAPD) and patients on chronic hemodialysis with reuse cuprophan membranes (HD), and compared them to healthy controls. IL-1 beta and IL-Ra were measured by specific radioimmunoassay. IL-1 beta was undetectable in freshly harvested PBMC from healthy controls, CRF, CAPD or HD. In contrast, the content of IL-Ra in HD patients (2828 +/- 466 pg/ml) was significantly higher than that in healthy controls (643 +/- 53 pg/ml, P < 0.01), CRF (1097 +/- 320 pg/ml, P < 0.01) or CAPD (1398 +/- 390 pg/ml, P < 0.05). In endotoxin-stimulated PBMC, IL-1 beta production by HD patients (9375 +/- 1687 pg/ml) was not significantly different from healthy controls (8429 +/- 1621 pg/ml). However, endotoxin-stimulated IL-Ra production by HD patients (32,350 +/- 8276 pg/ml) was greater than that from healthy controls (11,284 +/- 1250 pg/ml, P < 0.001), CRF (12,263 +/- 2680 pg/ml, P < 0.01) or CAPD patients (11,822 +/- 1797 pg/ml, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Flosequinan: a vasodilator with positive inotropic activity.

Flosequinan is an oral arterial and venous vasodilator that is currently under investigation for the treatment of congestive heart failure. The effects of flosequinan on ventricular performance and myocardial contractility were studied in 10 patients with severe congestive heart failure during right and left cardiac catheterization. Sixty minutes after a 100 mg oral dose of flosequinan, the peak rate of rise in left ventricular pressure (dP/dt) increased from 940 +/- 180 to 1050 +/- 240 mm Hg/sec (p less than 0.05), while left ventricular end-diastolic pressure decreased from 32 +/- 5 to 26 +/- 8 mm Hg (p less than 0.05), and cardiac index increased (2.1 +/- 0.4 to 2.3 +/- 0.5 L/min/m2, (p less than 0.05). The mean pulmonary artery pressure and vascular resistance decreased from 40 +/- 8 to 33 +/- 12 mm Hg (p less than 0.05) and from 330 +/- 240 to 290 +/- 170 dyne-sec/cm5 (p less than 0.05), respectively. Heart rate, mean aortic pressure, right atrial pressure, systemic vascular resistance, and serum norepinephrine levels did not change significantly. The increase in left ventricular peak dP/dt that was concomitant with a decrease in left ventricular end-diastolic pressure, and no change in systemic arterial pressure or sympathetic tone, argue for a direct positive inotropic effect of flosequinan.

Adult↗