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Biomedical subjects

J S Borer

Publications and source records attributed to J S Borer.

At least 19 recordsLinked to original sources
PubMed1992

Prevalence of anticardiolipin antibody in isolated mitral or aortic regurgitation, or both, and possible relation to cerebral ischemic events.

Anticardiolipin antibodies (acLa) are associated with a thrombotic tendency (often involving cerebral ischemic events), are frequently present with systemic lupus erythematosus and have been found together with cardiac valve abnormalities. Previous studies evaluated patients characterized by the presence of acLa or lupus, precluding assessment of the frequency of acLa in those with valvular disease. This study aims to establish the prevalence of acLa in patients with valve disease in the absence of lupus and, furthermore, to determine the influence of acLa on the risk of cerebral events in valve disease. Eighty-seven consecutive patients with mitral or aortic regurgitation, or both, prospectively underwent enzyme-linked immunosorbent assay testing for immunoglobulin G (IgG) and M acLa, as did 24 normal subjects. AcLa values greater than or equal to 3 SD above the normal mean were considered "positive." Prior cerebral events were defined retrospectively. Of 87 patients with valvular disease, 26 had positive IgG acLa levels compared with 0 of 24 normal subjects (p less than 0.01). AcLa values did not vary with valve disease etiology. Focal cerebral events had occurred in 8 patients and were embolic or probably embolic in 7, including 7 of 26 IgG acLa-positive and 1 of 60 IgG acLa-negative patients (p less than 0.001). In the absence of lupus, IgG acLa is highly prevalent among patients with aortic or mitral regurgitation, or both; this association may indicate a relatively high risk for cerebral emboli.

Adult↗
PubMed1992

Noninvasive laser-based blood pressure measurement in rabbits.

To obtain serial blood pressure measurements without trauma in rabbits, we developed a laser-based method which permits noninvasive determination of systolic and diastolic arterial blood pressure. The ease and accuracy of this method were evaluated over a range of blood pressures in five New Zealand White rabbits. Laser-based pressures from the central ear artery were compared with cannula-based pressures from the contralateral central ear artery. Pressures were measured before and during infusions of saline (control), nitroprusside, or epinephrine, and following induction of anesthesia. Noninvasive measurements correlated highly with direct measurements (systole: r = 0.89; diastole: r = 0.93). The difference between the non-invasive and direct pressure measurements during saline, nitroprusside, and epinephrine infusions, and following anesthesia, respectively, were (mean +/- SD, systole/diastole): 4.2 +/- 2.4 (P = NS)/9.3 +/- 1.4 (P less than .001), 4.1 +/- 1.6 (P less than .02)/3.2 +/- 1.1 (P less than .01), 0.6 +/- 2.4 (P = NS)/-3.0 +/- 2.7 (P = NS), and -5.1 +/- 2.9 (P = NS)/0.3 +/- 1.3 (P = NS). The noninvasive method did not result in observable agitation of the animals. To optimize results, visual inspection was required to assure that the instrument's diaphragm was not deformed or dried from previous use, and that the diaphragm was placed over the center of the arterial lumen. It was also necessary to dim room lights and to direct heating lights away from the ears to avoid degrading light signal quality. These results, albeit involving a small number of animals, indicate the potential utility of this method in the study of chronic pathophysiological processes requiring long-term repeated determination of systolic and diastolic blood pressure.

Animals↗
PubMed1992

Left ventricular diastolic and systolic performance during chronic experimental aortic regurgitation.

To study the time course of left ventricular structural and functional responses to chronic aortic regurgitation, aortic regurgitation was surgically induced in rabbits, and Doppler echocardiography was performed preoperatively and serially postoperatively for up to 2.5 yr. Twenty-five New Zealand White rabbits underwent surgical induction of aortic regurgitation and 13 control animals underwent sham operation. Left ventricular endocardial and epicardial surfaces were digitized from M-mode echocardiograms to measure the rates of change of cavity dimensions and wall thicknesses during diastolic relaxation and systolic contraction. Aortic regurgitant animals developed left ventricular dilatation and eccentric hypertrophy that remained relatively stable throughout the follow-up period. Compared with baseline values, left ventricular mass increased 120% and left ventricular internal dimension at end diastole increased 40%, whereas posterior wall thickness at end diastole and fractional shortening remained relatively stable. Left ventricular diastolic performance was enhanced at 6 mo after operation, a finding associated with increased volume load and heart rate following induction of aortic regurgitation. Diastolic performance was then reduced at 12 mo after operation and demonstrated no further decline throughout the remainder of the follow-up period. In contrast, left ventricular systolic performance was not altered following operation and remained preserved until the final assessment at up to 2.5 yr. Thus alterations in diastolic performance occurred without impairment of systolic performance during long-term follow-up of chronic experimental aortic regurgitation.

Animals↗
PubMed1991

Identification of "surgical" coronary anatomy by exercise radionuclide cineangiography.

Radionuclide cineangiography with exercise has been used to identify patients with coronary arteriographic patterns for which bypass grafting has been shown to prolong life. However, patients with severe prior myocardial damage were included in these studies, although the randomized medicine versus surgery trials recognized an effect of resting ejection fraction on operative risk and excluded patients with severely compromised function. Moreover, continuing reports from trials of surgery and from an ancillary evaluation of angioplasty have refined the set of coronary anatomic patterns for which mechanical therapy prolongs life, although stenosis severity criteria varied (50 vs 70 to 75%) between these trials. In this study, we have focused on patients who would have been eligible for the randomized trials of surgical therapy, and included only those with at least moderately preserved ventricular function at rest (ejection fraction greater than or equal to 30%). In such patients, exercise parameters were significantly more accurate than rest variables in identifying all anatomic patterns appropriately treated mechanically; logistic regression selected ejection fraction change with exercise, followed by systolic blood pressure change with exercise, as the 2 most powerful independent covariates among patients with "surgical" coronary anatomy defined by a 70% stenosis criterion; absolute exercise ejection fraction contributed no significant independent information. When defined at a 50% stenosis severity level, blood pressure change and angina class were more powerful than absolute exercise ejection fraction, but a crude, noninvasively determined analog of stroke work, incorporating change in both ejection fraction and blood pressure, was most accurate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Right ventricular function in severe non-ischaemic mitral insufficiency.

Mitral insufficiency (regurgitation) is a disease of both ventricles. To determine the pathophysiological implications and clinical value of assessment of right ventricular function in this disease, right ventricular ejection fraction was determined by radionuclide cineangiography (r = 0.73, P less than 0.01, vs contrast angiography, n = 30) in patients with severe, non-ischaemic mitral regurgitation. Among 31 patients with isolated mitral regurgitation treated medically, five died, all within 2 years of follow-up; all five were among the eight patients with left ventricular ejection fraction less than or equal to 45% (lower limit of normal), and among the six patients with right ventricular ejection fraction less than or equal to 30% (almost invariably associated with at least mild pulmonary hypertension). During the same period, valve replacement was performed in 22 patients with isolated mitral regurgitation; among the six patients with right ventricular ejection fraction less than or equal to 30% before operation, only one died (P less than 0.05), indicating the risk-mitigating effect of valve replacement. Among eight pre-operative patients with combined mitral and aortic regurgitation, four died within 7 years after double valve replacement; all patients with right ventricular ejection fraction during exercise less than 20% died. After mitral valve replacement for isolated mitral regurgitation, right ventricular ejection fraction improved rapidly (average 8% in less than 1 year (P less than 0.05); 3% more at 3 years after operation (P less than 0.05)). Post-operative symptom persistence was predictable from ventricular ejection fraction before operation less than 30% (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1991

Hemodynamic changes during retrograde left-heart catheterization in patients with aortic stenosis.

Pulmonary artery pressures in patients with aortic stenosis have been related to postoperative prognosis and surgical risk. However, while right- and left-heart pressures should be measured simultaneously, a catheter lying across the stenotic aortic valve might alter left- and right-heart pressures. To assess this phenomenon, right- and left-heart pressures were recorded before and after retrograde crossing of the aortic valve in 51 patients (30 patients with and 21 without aortic stenosis). In aortic stenosis, the mean pulmonary artery pressure increased (p less than 0.001) after transaortic valvular pressure catheter placement (average 4 mm Hg, peak 19 mm Hg); in the absence of aortic stenosis, the mean pulmonary artery pressure did not change (average 0 mm Hg; NS). A similar response was noted for the mean pulmonary capillary wedge pressure. Hemodynamic changes did not correlate with the severity of aortic stenosis or with left ventricular performance. Right-heart pressures should be determined without transaortic valvular catheter in place, if accurate interpretation of the hemodynamic effects of aortic stenosis is to be achieved.

Aortic Valve Stenosis↗
PubMed1991

Anticardiolipin antibody and stroke: possible relation of valvular heart disease and embolic events.

To establish the etiology of strokes related to the anticardiolipin antibody (Acla) syndrome and to determine the relationship of valvular heart disease and stroke in the presence of the Acla, clinical and objective characteristics of 21 patients with Acla, focal cerebral ischemic events were retrospectively analyzed. Twelve (86%) of 14 patients with stroke and 3 (42%) of 7 patients with non-stroke cerebral ischemic events had echocardiographic evidence of left-sided valvular abnormalities. Features characteristic of cardioembolic stroke were present in 12 (86%) of the 14 patients with stroke. The strength of the association between valvular disease and stroke, combined with the clinical and radiologic features noted, suggest that strokes related to the Acla syndrome typically are embolic, from a cardiac source.

Adult↗
PubMed1991

A theoretical comparison of first-pass and gated equilibrium methods in the measurement of systolic left ventricular function.

First-pass and gated equilibrium radionuclide studies of left ventricular function have proven extremely useful in the detection and management of patients with heart disease. Despite this practical experience, however, comparison of these methods generally has been confined to procedural differences that do not reflect the intrinsic properties of the methods. Here, we describe the results of a simple theoretical calculation from first principles that compares the methods based on their relative statistical precision. This analysis assumes that each procedure is carried out with the same tracer dose in the same hypothetical patient under identical conditions and with the same ideal imaging equipment. Results obtained with this model suggest that the imaging time required for a gated equilibrium study to achieve the same statistical precision as a first-pass study is typically less than 2 min in resting subjects and less than 1 min during stress. The analysis also indicates that gated equilibrium studies will tend to possess the greater statistical precision when cardiac output is elevated, such as when the heart is imaged during exercise. On the other hand, this analysis indicates that the first-pass method will tend to possess the greater precision when cardiac output is low and when imaging time is highly constrained.

Gated Blood-Pool Imaging↗
PubMed1991

Natural history of left ventricular performance at rest and during exercise after aortic valve replacement for aortic regurgitation.

Previous studies of left ventricular performance in aortic regurgitation uniformly indicate improvement within the year after aortic valve replacement but differ regarding the likelihood of additional later improvement. To resolve this difference, to more precisely define the pattern of postoperative left ventricular performance variation, and to assess the impact of valve replacement on ejection fraction during exercise, we evaluated radionuclide cineangiograms obtained annually or nearly annually for approximately 5 years in 21 prospectively studied patients who had undergone valve replacement for aortic regurgitation. Ejection fraction rose from less than 8 months before operation to 5-11 (average 7) months after operation and continued to rise for 1 additional year (rest) and 2 additional years (exercise) before reaching a stable plateau until the final study 54-72 (average 63) months postoperatively. Mean ejection fractions at rest were 45% preoperatively, 50% less than 1 year postoperatively (p = 0.12), 54% at year 1-2 (p = 0.01 versus less than 1 year), 56% at year 2-3 (NS versus year 1-2) and year 4-6 (NS versus year 1-2 or 2-3), and during exercise were 39% preoperatively, 49% less than 1 year postoperatively (p less than 0.01), 54% at year 1-2 (p less than 0.01 versus less than 1 year, NS versus year 2-3, p less than 0.05 versus year 4-6), 60% at year 2-3, and 61% at year 4-6 (NS versus year 2-3). Late improvement was found most consistently among patients with relatively depressed performance before operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1990

Preoperative left and right ventricular performance in combined aortic and mitral regurgitation and comparison with isolated aortic or mitral regurgitation.

Left and right ventricular performance characteristics in operative candidates with combined aortic and mitral regurgitation (AR/MR) have not been well defined. Therefore, we determined radionuclide cineangiographic ejection fractions, as well as echocardiographic and hemodynamic parameters, in 8 symptomatic patients undergoing double-valve replacement with pure, severe AR/MR. In order to gain insight into the basis for the poor postoperative survival in patients with this intrinsically biventricular disease, we compared these results with those of 29 symptomatic patients with isolated AR and with 18 symptomatic patients with isolated MR, all also undergoing valve replacement. Before operation, patients with AR/MR had significantly lower left ventricular (LV) ejection fraction than patients with MR (rest, 40 +/- 9% vs 52 +/- 10%, p less than 0.025; exercise, 35 +/- 12% vs 54 +/- 12%, p less than 0.005) and tended to have lower LV ejection fraction than patients with AR alone (rest, 40 +/- 9% vs 45 +/- 12%, difference not significant; exercise, 35 +/- 12% vs 39 +/- 11%, difference not significant); right ventricular (RV) ejection fraction was lower in AR/MR than in AR (p less than 0.01), and tended to be lower than in MR (difference not significant). At average postoperative follow-up of 72 to 76 months (survivors in each group), symptomatic patients with AR/MR had significantly poorer survival than symptomatic patients with isolated MR (p less than 0.05) and were more likely to have persistent symptoms than patients with AR (p less than 0.05). These findings suggest that symptomatic patients with AR/MR have poorer LV and RV performance than similarly symptomatic operative candidates with AR or MR alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve Insufficiency↗
PubMed1990

Relation of obesity, high sodium intake, and eccentric left ventricular hypertrophy to left ventricular exercise dysfunction in essential hypertension.

PURPOSE: To elucidate determinants of abnormal left ventricular functional responses to exercise in hypertensive patients. PATIENTS AND METHODS: One hundred twenty-seven patients with uncomplicated essential hypertension were studied by rest and exercise radionuclide angiography and by echocardiography at rest. RESULTS: The 24 patients with subnormal left ventricular ejection fraction at peak exercise (less than 54%) were similar in age and rest and exercise blood pressures to the 103 with normal exercise ejection fraction, but were more obese (p less than 0.005) and had greater left ventricular mass (p less than 0.03) and internal dimensions (p less than 0.001). The parallel increase in left ventricular chamber size and mass (eccentric hypertrophy) in the group of patients with exercise dysfunction was associated with higher resting end-systolic wall stress (p less than 0.001) and abnormal increases of end-systolic left ventricular volume from rest to peak exercise (p less than 0.001). Multivariate analysis revealed that exercise left ventricular dysfunction was independently associated with higher left ventricular mass (p less than 0.0005), end-systolic wall stress (p less than 0.001), dietary sodium intake (p less than 0.01), and body mass index (p less than 0.03). CONCLUSION: Among patients with uncomplicated essential hypertension, abnormal functional responses to exercise are strongly associated with eccentric ventricular hypertrophy, obesity, and high sodium intake.

Cardiomegaly↗
PubMed1990

Relative insensitivity of densitometric stenosis measurement to lumen edge determination.

Coronary artery stenosis measurement from coronary arteriograms is dependent on lumen edge determination. In theory, dependence may be minimized by densitometric integration of the entire lumen as compared with densitometric determination of edges alone coupled with calculation of lumen size by geometric formulas. To assess the impact of approximations of lumen border position when densitometric and geometric methods are employed, external, intermediate and internal borders were defined and used with each method to calculate lumen narrowing from images of contrast-filled, asymmetrically stenotic model vessels and from clinically generated coronary arteriograms. Actual cross-sectional area narrowing of models correlated almost perfectly with densitometric narrowing for each of the three border criteria (external: r = 0.99, n = 192; intermediate: r = 0.99, n = 192; internal: r = 0.99, n = 192). Lumen narrowing calculated by assuming a circular lumen geometry with a diameter equal to the distance between these identical borders correlated less well with true area narrowing (external: r = 0.79, n = 192; intermediate: r = 0.83, n = 192; internal: r = 0.78, n = 192); the residual variance of the densitometric regression was significantly less than that of the geometric regression for each of the three border criteria (external: 8.13 versus 372, p less than 0.001; intermediate: 7.39 versus 315, p less than 0.001; internal: 7.13 versus 531, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

Relationship of atrial natriuretic factor to left ventricular volume and mass.

Although atrial natriuretic factor is primarily of atrial origin, recent observations indicate that the hormone is also synthesized by hypertrophied left ventricular myocardium. To assess the separate influences of left ventricular and left atrial dilatation and left ventricular hypertrophy on human atrial natriuretic factor levels, left atrial dimension and volume and left ventricular dimension and mass were compared in 49 normal subjects, in 33 patients with chronic aortic regurgitation, and in 15 patients with chronic mitral regurgitation. When compared with normal subjects, patients with chronic aortic and mitral regurgitation had similarly dilated and hypertrophied left ventricles (p less than 0.0005), while only mitral regurgitation patients had significantly enlarged (p less than 0.0005) mean left atrial dimension and volume. Likewise, plasma atrial natriuretic factor was elevated among patients with mitral regurgitation (60.3 +/- 47.0 fmol/ml) but was normal in patients with aortic regurgitation (19.0 +/- 11.0 fmol/ml versus 12.4 +/- 5.2 fmol/ml in normals; both p less than 0.0005 versus mitral regurgitation). Among all 97 subjects, atrial natriuretic factor levels correlated more closely with left atrial dimension and volume (r = 0.62 and 0.64, p less than 0.0005) than with left ventricular dimension (r = 0.44, p less than 0.0005) or mass (r = 0.40, p less than 0.0005). In addition, multivariate analysis indicated that left atrial volume bore a stronger independent relationship to plasma atrial natriuretic factor levels than either age or left ventricular variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve Insufficiency↗