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Biomedical subjects

A S Blaustein

Publications and source records attributed to A S Blaustein.

At least 19 recordsLinked to original sources
PubMed2001

Non-Q-wave myocardial infarction following thrombolytic therapy: a comparison of outcomes in patients randomized to invasive or conservative post-infarct assessment strategies in the Veterans Affairs non-Q-wave Infarction Strategies In-Hospital (VANQWISH) Trial.

OBJECTIVES: We wished to determine the effect of post-infarct management strategy on event rates (death or recurrent nonfatal myocardial infarction [MI]) in patients who evolved non-Q-wave MI (NQMI) following thrombolytic therapy. BACKGROUND: Patients who evolve NQMI following thrombolytic therapy are often considered to be at high risk and are frequently managed with routine early invasive testing despite a lack of data supporting improved outcome. METHODS: The Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) study included 115 patients who evolved NQMI following thrombolytic therapy. We compared the event rates in patients randomized to routine early coronary angiography with those in patients randomized to a conservative strategy of noninvasive functional assessment, with angiography reserved for patients with spontaneous or induced ischemia. RESULTS: During an average follow-up of 23 months, 19 of 58 patients (33%) randomized to the invasive management strategy died or suffered recurrent nonfatal MI, compared with 11 of 57 patients (19%) randomized to the conservative strategy (p = 0.152). Equivalent numbers of patients were subjected to revascularization (percutaneous transluminal coronary angioplasty or coronary artery bypass graft). There were more deaths in the invasive management group than in the conservative management group (11 vs. 2). Excess deaths could not be attributed to periprocedural mortality. CONCLUSIONS: Overall event rates (death or recurrent nonfatal MI) are comparable with conservative and invasive strategies in patients who evolve NQMI following thrombolytic therapy. Mortality rate in patients managed conservatively is low (3.5%), and routine invasive management may be associated with an increased risk of death.

Aged↗
PubMed1998

Outcomes in patients with acute non-Q-wave myocardial infarction randomly assigned to an invasive as compared with a conservative management strategy. Veterans Affairs Non-Q-Wave Infarction Strategies in Hospital (VANQWISH) Trial Investigators.

BACKGROUND: Non-Q-wave myocardial infarction is usually managed according to an "invasive" strategy (i.e., one of routine coronary angiography followed by myocardial revascularization). METHODS: We randomly assigned 920 patients to either "invasive" management (462 patients) or "conservative" management, defined as medical therapy and noninvasive testing, with subsequent invasive management if indicated by the development of spontaneous or inducible ischemia (458 patients), within 72 hours of the onset of a non-Q-wave infarction. Death or nonfatal infarction made up the combined primary end point. RESULTS: During an average follow-up of 23 months, 152 events (80 deaths and 72 nonfatal infarctions) occurred in 138 patients who had been randomly assigned to the invasive strategy, and 139 events (59 deaths and 80 nonfatal infarctions) in 123 patients assigned to the conservative strategy (P=0.35). Patients assigned to the invasive strategy had worse clinical outcomes during the first year of follow-up. The number of patients with one of the components of the primary end point (death or nonfatal myocardial infarction) and the number who died were significantly higher in the invasive-strategy group at hospital discharge (36 vs. 15 patients, P=0.004, for the primary end point; 21 vs. 6, P=0.007, for death), at one month (48 vs. 26, P=0.012; 23 vs. 9, P=0.021), and at one year (111 vs. 85, P=0.05; 58 vs. 36, P= 0.025). Overall mortality during follow-up did not differ significantly between patients assigned to the conservative-strategy group and those assigned to the invasive-strategy group (hazard ratio, 0.72; 95 percent confidence interval, 0.51 to 1.01). CONCLUSIONS: Most patients with non-Q-wave myocardial infarction do not benefit from routine, early invasive management consisting of coronary angiography and revascularization. A conservative, ischemia-guided initial approach is both safe and effective.

Angioplasty, Balloon, Coronary↗
PubMed1998

Tricuspid valve disease. Clinical evaluation, physiopathology, and management.

The tricuspid and mitral valves are homologous whose function depends on coordination among components. Isolated tricuspid valve abnormalities are relatively uncommon. Rheumatic disease, chemicals, immunologic and degenerative disorders alter leaflet anatomy and may result in either stenosis, insufficiency or a combination. More often, tricuspid disorders present as a component of congenital syndromes or secondary to pulmonary vascular or let heart disease which alter geometry and function of nonleaflet components.

Blood Flow Velocity↗
PubMed1998

Design and baseline characteristics of the Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) trial. VANQWISH Trial Research Investigators.

OBJECTIVES: The Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) trial was designed to compare outcomes of patients with a non-Q wave myocardial infarction (NQMI) who were randomized prospectively to an early "invasive" strategy versus an early "conservative" strategy. The primary objective was to compare early and late outcomes between the two strategies using a combined trial end point (all-cause mortality or nonfatal infarction) during at least 1 year of follow-up. BACKGROUND: Because of the widely held view that survivors of NQMI are at high risk for subsequent cardiac events, management of these patients has become more aggressive during the last decade. There is a paucity of data from controlled trials to support such an approach, however. METHODS: Appropriate patients with a new NQMI were randomized to an early "invasive" strategy (routine coronary angiography followed by myocardial revascularization, if feasible) versus an early "conservative" strategy (noninvasive, predischarge stress testing with planar thallium scintigraphy and radionuclide ventriculography), where the use of coronary angiography and myocardial revascularization was guided by the development of ischemia (clinical course or results of noninvasive tests, or both). RESULTS: A total of 920 patients were randomized (mean follow-up 23 months, range 12 to 44). The mean patient age was 61 +/- 10 years; 97% were male; 38% had ST segment depression at study entry; 30% had an anterior NQMI; 54% were hypertensive; 26% had diabetes requiring insulin; 43% were current smokers; 43% had a previous acute myocardial infarction; and 45% had antecedent angina within 3 weeks of the index NQMI. CONCLUSIONS: Baseline characteristics were compatible with a moderate to high risk group of patients with an NQMI.

Angina Pectoris↗
PubMed1996

Indications for and timing of surgical intervention in infective endocarditis.

Infective endocarditis, especially when it involves prosthetic valves, is a serious, often fatal illness. Although antibiotics are essential in management, surgery is required in many patients who develop even incipient heart failure and structural complications. Early identification and referral results in improved mortality and morbidity rates, and there is evidence that surgery should play a larger role in managing infective endocarditis. Patients with intracardiac pacemakers and cardioverting devices represent a growing reservoir of patients with the potential to develop endocarditis.

Endocarditis, Bacterial↗
PubMed1995

Left ventricular dysfunction in deteriorating patients with chronic obstructive pulmonary disease.

OBJECTIVE: To evaluate the effectiveness of simple clinical variables and radionuclide ventriculogram in separating those patients with isolated chronic obstructive pulmonary disease (COPD) from those with COPD and coexisting left ventricular dysfunction (LVD). DESIGN: Retrospective record review of 77 patients with increasing dyspnea, defined as recent deterioration in exercise tolerance, new use of corticosteroids, or recent hospital admission for COPD; referred to the outpatient Pulmonary Rehabilitation Program at the Cincinnati Veterans Affairs Medical Center from July 1987 to October 1992. SETTING: Outpatient medical clinic. PATIENTS: Veterans who were referred to the Pulmonary Rehabilitation Program. MEASUREMENTS: History and physical findings, pulmonary function tests, arterial blood gases, distance achieved in a 12-min walk, dyspnea score, electrocardiogram, chest radiograph, and radionuclide multigated ventriculography. RESULTS: Twenty-five of 77 patients evaluated in the Pulmonary Rehabilitation Program for increasing dyspnea were functionally more limited (12-min walk 10.4 vs 13.9 laps; MRC score 2.68 vs 2.06; p < 0.05) and had left ventricular dysfunction (LVD) (left ventricular ejection fraction < 40%) associated with wall motion abnormalities on radionuclide ventriculogram. Careful standard clinical evaluation did not separate those patients with COPD from those with both COPD and LVD. CONCLUSIONS: LVD was found in 32% of patients with COPD presenting with symptomatic deterioration. Since the therapeutic approach to these two disorders differs, the identification of patients with LVD is important. Prospective studies are needed to identify the most cost-effective approach to this problem of coexisting disease and to evaluate the benefit from therapy.

Aged↗
PubMed1995

Preoperative and perioperative management of cardiac patients undergoing noncardiac surgery.

Cardiac diseases, particularly coronary artery disease and its risk factors, are associated with the majority of perioperative complications in patients undergoing major noncardiac surgery. Risks are remarkably low overall, yet for selected patients undergoing high-risk procedures, the chances of complications remain reasonably high. The literature has focused largely on identifying patients in whom complications are most likely to occur, using clinical assessment, including RFI, specialized cardiac testing, and perioperative monitoring. Characteristics of the patient and the surgery both influence outcomes. Current practices may have swung toward excessive testing, especially in patients whose surgical risks are low or moderate. Surprisingly little attention has been devoted to the evaluation of preoperative interventions for reducing perioperative risk. Some observations support the feasibility of performing noncardiac surgery in some high-risk groups using support devices or temporizing techniques. The general application of percutaneous or surgical revascularization as a means of reducing perioperative risk has not been assessed and to date represents an expensive and perhaps risky strategy. In patients who satisfy the usual symptomatic or prognostic criteria for coronary revascularization, its timing should depend on the urgency and risk of the noncardiac procedure. Finally, patients with cardiac devices--pacemakers, prosthetic valves, implantable debrillators, and antitachycardia devices--and survivors of congenital and transplant surgery have specific needs that require careful attention, going beyond the usual vigilance required in the perioperative period.

Adrenergic beta-Antagonists↗
PubMed1995

Characteristics of chronic left ventricular dysfunction induced by coronary embolization in a canine model.

We have characterized the coronary vascular reserve, left ventricular function and inotropic response in dogs with chronic heart failure consequent to intracoronary embolization (EMB) with 50 microns spheres. We conducted studies 12-39 months after embolization and contrasted the findings with normal (CON) dogs. Acute embolization produced sustained LV volume enlargement and increased wall thickness, reduction of LV ejection fraction and elevated end-diastolic pressures; resting catecholamine levels were also increased. Responses to phenylephrine, nitroprusside, and dobutamine were identical in CON and EMB and coronary vasodilator reserve was reduced despite larger coronary vascular volume. Analysis by light microscopy showed a diffuse focal and interstitial fibrosis distributed uniformly from endocardium to epicardium associated with 14% loss of myocytes. This created a functional separation of myocardial muscle bundles and a disruption of the syncytial nature of the heart. Electron microscopy of the areas of fibrosis revealed myocytes in states ranging from normal appearing, to ghosts with evidence of cytolysis and loss of the sarcolemma. This model of chronic congestive heart failure with LV systolic dysfunction and elevated LV diastolic pressures shares a number of features with the syndrome in humans.

Animals↗
PubMed1989

Stress-shortening relations and myocardial blood flow in compensated and failing canine hearts with pressure-overload hypertrophy.

Serial changes in left ventricular (LV) size and function during the adaptation to chronic pressure overload and the transition to pump failure were studied in 16 conscious dogs (aortic bands placed at 8 weeks of age). Echocardiographic data at baseline and at 3, 6, 9, and 12 months after banding revealed a progressive increase in LV mass in all dogs. In six dogs with LV pump failure, there was a progressive decline in circumferential fiber shortening (29 +/- 4% at 12 months); this was significantly less than that seen in five littermate controls (38 +/- 3%, p less than 0.05). The average LV to body weight ratio in this group was 9.8 +/- 2.7 g/kg. In 10 dogs without pump failure (compensated LVH group), shortening exceeded that seen in the controls (43 +/- 4%, p less than 0.05); the LV to body weight ratio was 7.7 +/- 1.0 g/kg. At 12 months (cardiac catheterization), the LV end-diastolic pressure was higher in the failure (25 +/- 15 mm Hg) than in the compensated group (8 +/- 5 mm Hg, p less than 0.05); mean systolic stress was also higher in the failure group (313 +/- 67 g/cm2) than in the compensated group (202 +/- 53 g/cm2, p less than 0.05). The transmural distribution of myocardial blood flow was measured (at 12 months) with the radioactive microsphere technique; flow data were then related to an index of demand (a stress-time index). There was preferential blood flow to the subendocardial layers in the control (endo/epi = 1.28) and compensated hearts (endo/epi = 1.10), but in the failure group there was a relative decrease in subendocardial flow (endo/epi = 0.92). However, the absolute values for subendocardial flow in the normal, compensated, and failure groups were 77 +/- 54, 125 +/- 48, and 113 +/- 64 ml/min/100 g; the stress-time indexes in the subendocardial shell were 38 +/- 11, 74 +/- 19, and 93 +/- 34 g sec.10(2)/cm2/min. Despite what appears to be a marginal balance between blood flow and the stress time index in the failure group, the myocardial high energy phosphates were not depleted and the inoptropic state was not depressed. In this model of LV hypertrophy, the observed differences in fiber shortening can be explained on the basis of the inverse afterload-shortening relation; pump failure was due to an inadequate LV hypertrophy with afterload excess.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1989

The effect of acute alterations in left ventricular afterload and beta-adrenergic tone on indices of early diastolic filling rate.

The effects of an acute increase in left ventricular systolic pressure and the effects of an intravenous isoproterenol infusion on myocardial (segment) lengthening rate and chamber (minor axis dimension) filling rate were examined in 12 anesthetized dogs. Measurements of left ventricular systolic pressure (by micromanometer) and of segment length and chamber dimension transients (by ultrasonic crystals) were made in variably afterloaded beats (three-beat descending aortic cross-clamp) before and during an isoproterenol infusion that raised (+)dP/dt by 40%. During the baseline state, we found an inverse relation between the peak rate of increase in minor axis dimension [(+)dD/dt] and systolic pressure over a wide range of systolic pressures (110-160 mm Hg) and end-systolic dimensions (25-40 mm); peak (+)dD/dt and end-systolic dimension were also inversely related. During isoproterenol infusion, end-systolic dimension fell from 29.7 +/- 3.1 to 28.0 +/- 3.1 mm and (+)dD/dt increased from 79.6 +/- 8.0 to 90.1 +/- 8.7 mm/sec; however, the slope and y intercept of the relation between (+)dD/dt and end-systolic dimension were unchanged. Peak (+)dD/dt at a common end-systolic dimension of 31 mm was nearly equal during baseline and isoproterenol states (64.2 +/- 6.3 vs. 65.1 +/- 6.6 mm/sec). Similar results were found using segment length transients. We interpret these data to indicate that (+)dD/dt is strongly influenced by changes in systolic pressure and dimension and that isoproterenol-induced changes in (+)dD/dt are mediated, at least in part, through changes in systolic pressure and dimension.

Animals↗
PubMed1988

Effect of propranolol on the left ventricular response to the Valsalva maneuver in normal subjects.

Ten normal subjects performed the Valsalva maneuver before and after the administration of propranolol (1 mg/kg). Changes in left ventricular (LV) size and function were assessed with noninvasive techniques (echocardiography and sphygmomanometer). Data were obtained at baseline, at 20 seconds of the strain phase (phase II) and 10 seconds after the release of strain (phase IV). In the control state (before propranolol), blood pressure decreased during phase II and exceeded baseline after the release of strain ("overshoot") in phase IV; after the administration of propranolol, the pressure overshoot characteristic of phase IV was no longer present. End-diastolic dimension decreased during the strain phase, but returned to baseline values during recovery in both control and propranolol states. LV stress-dimension and stress-shortening relations before and after propranolol indicate that an increase in LV contractility beginning during phase II and extending into phase IV was attenuated after propranolol. Although the absence of phase IV blood pressure overshoot may be clinically useful in identifying patients with impaired left ventricular function, beta-adrenergic receptor blocking agents can also produce this hemodynamic response in the presence of normal ventricular function.

Adult↗
PubMed1987

Comparison of contractile state and myosin isozymes of rat right and left ventricular myocardium.

We compared myocardial mechanics and myosin isozymes of right and left ventricular papillary muscles from adult (6 to 8 month old) male rats. Analysis of force velocity relations indicate that right ventricular papillary muscles contract more rapidly than left at light loads (2.68 +/- 0.13 vs 2.18 +/- 0.07 muscle lengths/s measured 75 ms following stimulation, at 0.5 g/mm2; P less than 0.01). Right ventricular papillary muscles had significantly more of the alpha heavy chain containing V1 myosin isozyme and less of the V3 containing beta heavy chain myosin isozyme than left ventricular preparations (P less than 0.05). Papillary muscle and ventricular free wall myosin isozyme distribution were not significantly different within their respective chambers. The presence of a relatively larger proportion of the alpha heavy chain containing myosin isozyme (V1) in right ventricle papillary muscles relative to left correlated with the more rapid velocities of shortening seen in right ventricular papillary muscles (r = 0.60; P less than 0.01).

Animals↗
PubMed1987

Right ventricular pacing reduces the rate of left ventricular relaxation and filling.

Right ventricular pacing alters left ventricular synchrony and loading conditions, each of which may independently influence left ventricular relaxation. Addition of a properly timed atrial contraction by using sequential atrioventricular (AV) pacing minimizes changes in left ventricular loading conditions, but ventricular asynchrony persists. To separate the effects of altered loading from those of asynchrony, the effects of right ventricular pacing and sequential AV pacing on the rate of isovolumic pressure decline (relaxation time constant), myocardial (segment) lengthening rate and chamber (minor axis dimension) filling rate were examined. In 12 open chest anesthetized dogs, left ventricular pressure (micromanometer) and either left ventricular free wall segment length transients (n = 6) or minor axis dimension transients (n = 6) were measured during right atrial, right ventricular and sequential AV pacing; length and dimension were measured using ultrasonic crystals. Compared with right atrial pacing, right ventricular pacing produced a decrease in systolic pressure, a reduction in fractional shortening, a prolongation of the relaxation time constant (23.5 +/- 0.7 to 29.8 +/- 0.8 ms, p less than 0.05), slower peak segment lengthening rate (6.2 +/- 0.6 to 4.6 +/- 0.8 s-1, p less than 0.05) and a slower rate of increase in chamber dimension (3.5 +/- 0.1 to 2.7 +/- 0.1 s-1, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Elevated CK-MB with normal total creatine kinase in suspected myocardial infarction: associated clinical findings and early prognosis.

To test the hypothesis that patients with normal serum levels of creatine kinase (CK) but elevated percentages of MB isoenzyme fractions in suspected myocardial infarction may have sustained clinically significant events, we studied the hospital course of 347 consecutive patients admitted with suspected myocardial infarction. Two hundred twenty-three patients had normal CK levels (182 +/- 44 IU) and normal MB percentages (normal group), 68 had elevated levels of both CK (1395 +/- 178 IU) and MB percentage (10.5 +/- 0.6) (macroinfarction group), and 40 had normal CK levels (96 +/- 7 IU) but elevated MB percentages (9.6 +/- 0.5) with typical enzyme curves (microinfarction group). Compared to the normal group, microinfarction patients were older, had more congestive heart failure, required more intensive monitoring and therapy during longer stays, and sustained a higher in-hospital mortality rate. Thus, these microinfarction patients are at increased risk and therefore warrant aggressive treatment and further evaluation.

Acute Disease↗
PubMed1986

Serial effects on left ventricular load and contractility during hemodialysis in patients with concentric hypertrophy.

To separate the effects of hemodialysis on loading conditions from those on contractile state, six patients with concentric left ventricular hypertrophy and normal left ventricular function were studied before, during, and after hemodialysis. Two-dimensional-directed M-mode ultrasound was used to measure left ventricular dimensions and wall thickness; a sphygmomanometer and carotid pulse recording were used to determine peak and end-systolic blood pressure. From these data, meridional stress at end systole was calculated and stress-dimension and stress-shortening relations were derived; measurements of metabolic parameters were made simultaneously. Heart rate and systolic blood pressure were stable throughout dialysis. Reductions in left ventricular dimensions and increased shortening were evident by 30 minutes of dialysis and were largely complete by mid-dialysis. These changes coincided with a decrease in potassium and an increase in ionized calcium but not in pH, which changed only in the latter half of dialysis. When stress-dimension and stress-shortening relations were examined, both individual and group data for all coordinates before, during, and after dialysis demonstrated an excellent linear fit consistent with a single contractile state. We conclude that in stable patients with left ventricular hypertrophy, the reduction in heart size and improvement in shortening are due primarily to reductions in preload and afterload.

Blood Pressure↗
PubMed1986

Mechanisms of pulsus paradoxus during resistive respiratory loading and asthma.

To determine the mechanisms of pulsus paradoxus during asthma, six subjects known to have cold air bronchial hyperreactivity were studied while in a quiescent phase of their disease. All were free of significant airway obstruction at the time of study. After placement of an esophageal balloon to estimate intrathoracic pressure, the subjects were assessed during quiet breathing, resistive airway loading and then during a stable period of airway obstruction induced by cold air. Steady state left ventricular volume and performance were measured using radionuclide ventriculography; right ventricular volume was calculated from the stroke volume ratio and right ventricular ejection fraction. Cardiac cycles were segregated according to their occurrence in inspiration or expiration using a flow signal from a pneumotachograph. Combined inspiratory and expiratory resistance produced pulsus paradoxus and changes in esophageal pressure that were similar to those during asthma and significantly greater than those during quiet breathing. These changes were accompanied by decreases in left ventricular diastolic volume and stroke volume during inspiration, and increases in these variables during expiration; right ventricular volume and stroke volume demonstrated changes reciprocal to those seen in the left ventricle. These data indicate that during periods of increase in airway resistance, abnormal pulsus paradoxus results from an exaggeration in the normal inspiratory-expiratory difference in stroke volume mediated primarily by the effects of intrathoracic pressure on ventricular preload.

Adult↗
PubMed1986

Influence of exogenously generated oxidant species on myocardial function.

Oxygen-derived free radicals (OFR) have been implicated as mediators of tissue injury in various disease states. Their participation in myocardial injury due to ischemia-reperfusion has also been suggested. To characterize the mechanical dysfunction associated with OFR-induced injury, we studied alterations in isometric contractions of rat papillary muscle at 28 degrees C. A purine-xanthine oxidase system was used to generate OFR. Neither purine nor xanthine oxidase alone had significant effects on rest or active tension, duration of the contraction, or peak rates of tension development or decline. In contrast, their combination resulted in a reduction of active tension to 38% of base-line values without alteration in rest tension. This reduction was largely due to a decline in the peak rate of tension development. When catalase or superoxide dismutase was introduced into the bath prior to the generation of OFR, catalase but not superoxide dismutase offered essentially complete functional protection. These results substantiate that impaired myocardial function can result from exposure to OFR. In this case the active radicals appear to be either peroxides or hydroxyl and not superoxide. These observations provide a basis for understanding the functional protection afforded ischemic myocardium by OFR scavenging enzymes.

Animals↗