Biomedical subjects

K R Bailey

Publications and source records attributed to K R Bailey.

At least 181 records · Page 10Linked to original sources

PubMed1990

Serial Doppler echocardiographic follow-up of left ventricular diastolic function in cardiac amyloidosis.

A spectrum of left ventricular diastolic filling abnormalities noted on Doppler echocardiography has been demonstrated in patients with cardiac amyloidosis. To determine how these filling abnormalities evolve over time and the significance of any change, serial pulsed wave Doppler studies of left ventricular inflow were performed over 12.6 +/- 4.9 months in 41 consecutive patients (36 men and 15 women, mean age 59 +/- 11 years) with typical two-dimensional echocardiographic features of cardiac involvement. The measurements were peak left ventricular inflow in early diastole (E) and atrial contraction (A) velocities, E/A ratio, deceleration time and isovolumetric relaxation time. Patients were classified by mean left ventricular wall thickness into an early group (less than 15 mm) of 24 patients and an advanced group (greater than or equal to 15 mm) of 17 patients. The total group showed an increased E/A ratio (1.7 +/- 0.9 versus 1.4 +/- 0.9, p = 0.009) and decreased deceleration time (164 +/- 57 versus 174 +/- 51 ms, p = 0.11) at follow-up compared with baseline study. The early group showed significant changes in the E/A ratio (1.6 +/- 1.0 versus 1.2 +/- 0.7, p = 0.001) between the two studies. Seven patients (29%) in the early group showed a change from an abnormal relaxation or "normal" pattern to one of restriction, coincident with increased symptoms in six of these patients. Fifteen (88%) of the 17 patients in the advanced group did not show significant changes in the measures during the follow-up study, but these patients already showed a restrictive pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Amyloidosis↗

PubMed1990

Progression of aortic stenosis in adults: new appraisal using Doppler echocardiography.

This study examined progression of aortic stenosis (AS) as assessed by Doppler echocardiography. One hundred twelve consecutive adult patients had calcific AS and underwent three examinations during a mean 25-month period (range 7 to 54 months). At the time of entry into the study, mean values for initial peak aortic velocity and ejection fraction (EF) were 2.9 +/- 0.7 m/sec and 63 +/- 10%, respectively; 52% of the patients were symptomatic. At the third examination the percentage of symptomatic patients increased to 65% (p = 0.0039 compared to baseline values), and the aortic peak velocity increased to 3.3 +/- 0.8 m/sec (p less than 0.001). Age, sex, and EF were not predictors of progression. Documented coronary artery disease (in 57 patients) did not affect progression, and neither did the aortic peak velocity at the time of entry into the study. Thirty-eight patients reported an increase in symptoms from the first to third examination, and their rate of progression was significantly different from that of the rest of the population: 0.33 +/- 0.50 m/sec/yr compared to 0.18 +/- 0.26 m/sec/yr (p less than 0.03).

Aged↗

PubMed1990

Does intracoronary infusion of Fluosol-DA 20% prevent left ventricular diastolic dysfunction during coronary balloon angioplasty?

Distal intracoronary infusion of the perfluorochemical Fluosol-DA 20% has been shown to prevent systolic dysfunction during coronary artery balloon occlusion in coronary angioplasty. To assess its effect on global diastolic dysfunction, a randomized, single-blind, crossover protocol comparing intracoronary infusion of Fluosol or no infusion (control) was performed during 60 s balloon inflations in 10 patients (mean age 67 years) undergoing coronary angioplasty. Assessment of global systolic and diastolic function was obtained with high fidelity micromanometer measurements of left ventricular pressure. Eighteen pairs of balloon inflations (Fluosol versus control) were analyzed. Patients reported significantly less severe chest pain during inflations accompanied by Fluosol compared with control. However, during coronary balloon occlusion, no significant differences in the changes from baseline values were observed between Fluosol and control with regard to ventricular relaxation, including the time constant of early ventricular relaxation (tau) and maximal rate of fall in left ventricular pressure (maximal negative dP/dt). No differences between Fluosol and control were observed in terms of the increase in end-diastolic pressure or minimal diastolic pressure during balloon inflation. Mean systolic pressure decrease from baseline values was greater during control than during Fluosol inflations (-9.0 +/- 3.3 mm Hg, p = 0.013), but no significant difference was observed in the change in maximal rate of rise in left ventricular pressure (maximal positive dP/dt). These results suggest that Fluosol does not preserve global left ventricular diastolic function during coronary balloon occlusion, possibly because of its limited oxygen delivery capability relative to arterial blood.

Aged↗

PubMed1990

LV pressure-volume area and oxygen consumption: evaluation in intact dog by fast CT.

The relationship between left ventricular (LV) myocardial oxygen consumption (MVO2) and LV systolic pressure-volume area (PVA) was investigated in anesthetized closed-chest dogs with intact reflexes and subsequently with beta-adrenergic blockade, with or without simultaneous muscarinic blockade. LV chamber volumes were measured using a fast computerized tomography (CT) scanner (dynamic spatial reconstructor, DSR) at 33-ms intervals. Myocardial blood flow was measured from the DSR scans of aortic root angiograms. With intact reflexes, LV MVO2 (Y) related to PVA (X) values as Y = (4.28 +/- 1.81)X + (1.94 +/- 6.0) (n = 24) (mJ.g-1.cycle-1). With beta-adrenergic blockade, LV MVO2 (Y) related to PVA (X) value as Y = (4.24 +/- 1.03)X - (6.43 +/- 6.5), (n = 9) (mJ.g-1.cycle-1). With beta-adrenergic and muscarinic blockade, LV MVO2 (Y) related to PVA (X) value as Y = (2.84 +/- 1.72)X + (3.51 +/- 5.15), (n = 13) (mJ.g-1.cycle-1). The slopes of these regressions are higher than the slopes demonstrated by others in isolated ventricles but very similar to those demonstrated in open-chest dogs.

Adrenergic beta-Antagonists↗

PubMed1990

Improving the predictive ability of the signal-averaged electrocardiogram with a linear logistic model incorporating clinical variables.

To improve the predictive accuracy of the signal-averaged electrocardiogram, we created a linear logistic model for predicting ventricular tachycardia during electrophysiologic testing. This signal-averaged electrocardiographic model was created from data obtained from 214 patients undergoing electrophysiologic testing (70 had ventricular tachycardia during electrophysiologic testing) by using stepwise logistic regression to rank eight clinical and nine signal-averaged electrocardiographic variables. The best predictors were ejection fraction, history of infarction, ventricular ectopic pairs or nonsustained ventricular tachycardia on Holter monitoring, QRS duration after 25-Hz filtering, and root mean square voltage of the terminal 40 msec of the QRS complex after 40- and 80-Hz filtering. Cross validation (a statistical technique that can be used to accurately evaluate how a predictive model will perform on a prospective patient population) was used to validate the model. After cross validation, the model's sensitivity was 91% and specificity was 59% for predicting ventricular tachycardia during electrophysiologic testing. This model compared favorably with established 25-Hz late-potential criteria (QRS duration of more than 110 msec and root mean square voltage of less than 25 microV of the terminal 40 msec of the QRS complex; sensitivity, 64%; specificity, 85%) and with established 40-Hz late-potential criteria (QRS duration of more than 114 msec or root mean square voltage of less than 20 microV of the terminal 40 msec of the QRS complex or duration of the low-amplitude signal less than 40 microV at the terminal QRS complex that is greater than 38 msec; sensitivity, 84%; specificity, 54%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

Ultrasound guidance improves the success rate of internal jugular vein cannulation. A prospective, randomized trial.

STUDY OBJECTIVE: To compare conventional versus ultrasound-guided internal jugular vein cannulation techniques. DESIGN: Patients were randomly assigned to receive either conventional or two-dimensional ultrasound-guided internal jugular vein cannulation. Patients who could not be cannulated with five or fewer passes by either technique, were crossed over to the other technique. SETTING: Clinical research unit in a tertiary care center. PATIENTS: All consecutive patients who required urgent or urgent-elective internal jugular vein cannulation during the study period. INTERVENTIONS: The two-dimensional ultrasound transducer imaged all cannulation attempts. For patients randomized to ultrasound guidance, the operator viewed two-dimensional ultrasound images, and received verbal guidance from the ultrasound technician. For patients randomized to the conventional arm, two-dimensional ultrasound images were recorded without visual or verbal feedback. MEASUREMENTS AND MAIN RESULTS: Two-dimensional ultrasound was significantly better than conventional guidance in reducing the number of failed site cannulations from 6/17 (35 percent), to 0/12 (0 percent), p less than 0.05. Two-dimensional ultrasound also reduced the mean number of passes required to cannulate the vein from 3.12 to 1.75 (p less than .05), and was also successful in six/six (100) of patients who failed cannulation by conventional means (p less than 0.05). CONCLUSIONS: Intensivists can increase successful internal jugular vein cannulation using ultrasound guidance. Two-dimensional ultrasound should be considered for patients difficult to cannulate or those at high risk of cannulation complications.

Catheterization, Central Venous↗

PubMed1990

Reproducibility of ambulatory blood pressure load.

Twenty-two hypertensive patients were monitored during two separate drug-free occasions with a Del Mar Avionics ambulatory device. Blood pressure loads (percentage of systolic and diastolic readings more than 140 and 90 mmHg, respectively) and mean BP were measured both to determine their reproducibility and to examine how they correlate with each other. The systolic and diastolic mean awake BPs for day 1 and day 2 were 140/93 mmHg and 140/91 mmHg, respectively, and BP loads were 45%/55% and 43%/54%. Moreover, mean BP loads correlated highly (r = 0.93) with mean BP values taken on the same day. Both ambulatory mean SBP and BP load were highly reproducible (r = 0.87 and 0.80, respectively, during the awake hours), and mean DBP and load were fairly reproducible (r = 0.59 and 0.39, respectively, during the awake hours). Clinically, however, both were consistent from day 1 to day 2. Mean and individual standard deviations also were reproducible for both systolic and diastolic pressures and loads.

Adult↗

PubMed1990

Emergency "rescue" percutaneous transluminal coronary angioplasty after failed thrombolysis with streptokinase. Early and late results.

Although thrombolytic therapy has been a major advance in the treatment of acute myocardial infarction, in at least 25% of patients the artery remains occluded after administration. In these patients, the strategy of "rescue" or "salvage" angioplasty is frequently used although follow-up data are limited. Sixty-three patients underwent percutaneous transluminal coronary angioplasty (PTCA) after thrombolytic therapy for acute myocardial infarction. The decision to proceed with PTCA was based on physician preference and not a specific research protocol. In 34 of these selected patients, PTCA was performed as a rescue procedure because the infarct-related artery remained occluded (group 1); in 29 of these patients, it was performed to treat a severe but subtotal residual stenosis (group 2). PTCA successfully restored patency in 71% of group 1 and in 90% of group 2. Group 1 patients had a significantly worse baseline ejection fraction than did those in group 2 (47 +/- 13% vs. 58 +/- 13%, p = 0.0015). Group 1 patients also had a significantly worse predismissal ejection fraction (36 +/- 13% vs. 50 +/- 14%, p = 0.0004). During initial hospitalization, 14 (22%) patients underwent coronary bypass surgery. In-hospital mortality was low in each group (3% in group 1 and 0% in group 2). During a mean follow-up of 4 years, 89% of group 1 patients remained alive as compared with 97% of group 2 patients. This excellent 4-year survival rate, despite the depressed predismissal ejection fraction in patients undergoing rescue PTCA, raises the issue of whether acute reperfusion has a beneficial effect aside from any impact on myocardial salvage and preservation of left ventricular function.

Adult↗

PubMed1989

Two-dimensional echocardiographic findings in systemic sarcoidosis.

The records of 88 patients with systemic sarcoidosis who underwent 2-dimensional echocardiography were reviewed to define the typical echocardiographic abnormalities in patients with clinical evidence of cardiac involvement. Twelve patients (14%) had echocardiographic evidence of left ventricular systolic dysfunction attributed to cardiac sarcoidosis (segmental hypokinesis in 8 patients and global hypokinesis in 4 patients). A high incidence of congestive heart failure (9 of 12) and conduction system disease (7 of 12) was characteristic of these patients. The remaining 76 patients had normal echocardiograms or abnormalities attributed to nonsarcoid sources. In 8 (11%) of these 76 patients, there were significant clinically unexplained conduction abnormalities likely related to sarcoidosis.

Adult↗

PubMed1989

Safety and efficacy of percutaneous transluminal coronary angioplasty performed at time of diagnostic catheterization compared with that performed at other times.

Performing diagnostic cardiac catheterization and percutaneous transluminal coronary angioplasty (PTCA) as a single, combined procedure might provide savings in patient hospitalization days and more efficient use of catheterization laboratory time. To assess the safety and efficacy of combined diagnostic coronary angiography and PTCA, we reviewed all elective PTCA procedures performed at our institution during 1985 and 1986 so that we could compare patients who had diagnostic angiography and angioplasty on separate days (n = 404) with those who had the combined procedure (n = 120). The success rate and incidences of urgent bypass surgery, acute myocardial infarction, transient azotemia and procedure-related death were not different in the 2 groups. The mean hospitalization time was 6.2 days in the group with combined angiography and angioplasty, and 7.3 days in the group having separate procedures.

Angiography↗

PubMed1989

T-lymphocyte subsets in patients with idiopathic dilated cardiomyopathy.

T-cell subsets were measured in the peripheral blood of 33 patients with heart failure from idiopathic dilated cardiomyopathy, 22 patients with heart failure from other causes, and 33 normal controls. Mean T-suppressor cell percentage was 30% in normals, 21% in patients with idiopathic dilated cardiomyopathy whose duration of symptoms was less than 1 year (P = 0.0005), and 26% in those with symptoms for greater than 1 year (P = 0.05). Similarly, percentage of T-suppressor cells in the group with heart failure from causes other than idiopathic dilated cardiomyopathy was significantly lower (23%; P = 0.005) in those with short duration of symptoms. When both heart failure groups were combined those with symptoms for less than 1 year had significantly lower T-suppressor frequencies (22%) than those with symptoms for more than 1 year (P = 0.015). Multivariate analysis identified duration of symptoms and age as the only independent predictors of T-suppressor cell frequencies. Decreased percentage of T-suppressor cells in patients with idiopathic dilated cardiomyopathy may be an epiphenomenon related to duration of heart failure. This should be taken into account in assigning an etiologic mechanism for T-suppressor cells in idiopathic dilated cardiomyopathy.

Adult↗

PubMed1989

Doppler characterization of left ventricular diastolic function in cardiac amyloidosis.

Sixty-four patients with primary systemic amyloidosis-53 with two-dimensional echocardiographic features of cardiac involvement (Group I) and 11 without cardiac involvement (Group II)--underwent Doppler echocardiographic assessment of left ventricular diastolic function. Pulsed wave Doppler recordings of left ventricular inflow velocities and pulmonary vein flow velocities with respiratory monitoring in these patients were compared with findings in a normal group. Patients in Group I showed striking abnormalities of left ventricular diastolic filling when classified into subgroups by mean left ventricular wall thickness: early greater than 12 but less than 15 mm; advanced greater than or equal to 15 mm. In early amyloidosis, relaxation was abnormal, with decreased peak early velocity (75 +/- 20 versus 86 +/- 16 cm/s; p less than 0.01), increased late velocity (71 +/- 22 versus 56 +/- 13 cm/s; p less than 0.01), decreased early to late velocity ratio (1.2 +/- 0.6 versus 1.6 +/- 0.5; p less than 0.01) and prolonged isovolumic relaxation time (87 +/- 15 versus 73 +/- 13 ms; p less than 0.01) compared with normal values. In advanced amyloidosis, there was a restrictive filling pattern with a markedly shortened deceleration time (148 +/- 50 versus 199 +/- 32 ms; p less than 0.001), decreased pulmonary vein peak systolic flow velocity (34 +/- 16 versus 54 +/- 12 cm/s; p less than 0.01) and increased diastolic flow velocity (55 +/- 20 versus 44 +/- 12 cm/s; p less than 0.01) compared with normal values. Group and the subgroup with early amyloidosis had similar flow velocity patterns. Thus, this study documents that in cardiac amyloidosis, a spectrum of diastolic filling abnormalities exists; the restrictive filling pattern is seen only in the advanced stages.

Amyloidosis↗

PubMed1989

Cardiac tamponade: characteristic Doppler observations.

Abnormal respiratory variation in diastolic filling has been reported in patients with cardiac tamponade. To determine the characteristic diastolic filling abnormalities in this disorder, we recorded left ventricular isovolumic relaxation time and transvalvular and hepatic venous flow velocities by pulsed-wave Doppler echocardiography in 28 patients with pericardial effusion (16 with and 12 without cardiac tamponade) and 20 normal control subjects. The phase of respiration was recorded simultaneously with all profiles. In 13 of the 16 patients with cardiac tamponade, Doppler examination was repeated after pericardiocentesis. In patients with cardiac tamponade, respiratory variations in transvalvular flow velocities and isovolumic relaxation time were substantially increased in comparison with values in normal subjects, patients without tamponade, and those who had undergone pericardiocentesis. An exaggerated expiratory decrease in diastolic forward flow and increase in reverse flow in the hepatic vein also were characteristic of patients with cardiac tamponade. Thus, Doppler echocardiography is an additional noninvasive means of detecting hemodynamic compromise in patients with pericardial effusion.

Adult↗

PubMed1989

Effects of thrombin inhibition on the development of acute platelet-thrombus deposition during angioplasty in pigs. Heparin versus recombinant hirudin, a specific thrombin inhibitor.

The effect of recombinant hirudin and the dosage of heparin on acute platelet-thrombus deposition during carotid angioplasty in anesthetized pigs was prospectively assessed. Fifty-five animals (mean weight, 33.9 kg) were randomized to one of six heparin dosages: heparin boluses of 35, 50, 100, 150, 200, or 250 units/kg followed by a continuous infusion of 35, 50, 100, 150, 200, or 250 units/kg/hr, respectively. Another five pigs received a bolus of 1 mg/kg hirudin (recombinant desulphatohirudin), a specific thrombin inhibitor, followed by an infusion of 1 mg/kg/hr. Bilateral carotid angioplasty was performed in all pigs 20 minutes after starting the infusion; they were sacrificed 57 +/- 12 minutes after the procedure. Deep medial arterial injury was present in approximately 75% of the dilated segments, and subendothelial injury in the remaining 25%. Mean log of number of platelets and molecules of fibrinogen per centimeter squared of deep injury in segments from all the animals treated with heparin were 4.74 +/- 1.03 and 5.02 +/- 0.64, respectively. A regression analysis showed an inverse correlation of the log of platelet deposition with the heparin group (r = -0.56, p = 0.0001) with administered total units of heparin (r = -0.55, p = 0.0003) and with mean plasma heparin concentration (r = -0.55, p = 0.0004) in deeply injured arteries. Similar inverse relations were obtained for fibrinogen. In contrast, the deposition of platelets and fibrinogen in subendothelial injury was very low and independent of the heparin administered.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗

PubMed1989

Continuous wave Doppler echocardiographic measurement of prosthetic valve gradients. A simultaneous Doppler-catheter correlative study.

Studies correlating prosthetic valve gradients determined by continuous wave Doppler echocardiography with gradients obtained by cardiac catheterization have, to date, been limited to patients with mitral and tricuspid prostheses or have compared nonsimultaneous measurements. Simultaneous Doppler and catheter pressure gradients in 36 patients (mean age, 63 +/- 13 years) with 42 prosthetic valves (20 aortic, 20 mitral, one tricuspid, and one pulmonary) were studied. Catheter gradients were obtained using a dual-catheter technique. The simultaneous pressure tracings and Doppler flow velocity profiles were digitized at 10-msec intervals to derive the corresponding maximal and mean gradients. The correlation between the maximal Doppler gradient and the simultaneously measured maximal catheter gradient was 0.94 (SEE = 6), and that between the Doppler gradient and the simultaneously measured mean catheter gradient was 0.96 (SEE = 3). There were no significant differences in correlation between gradients for the 32 mechanical valves (maximal gradients: r = 0.95, SEE = 6; mean gradients: r = 0.96, SEE = 3) and the 10 bioprosthetic valves (maximal gradients: r = 0.89, SEE = 6; mean gradients: r = 0.93, SEE = 3). In patients with mitral prostheses, Doppler gradients correlated well with the corresponding catheter gradients obtained with direct measurement of left atrial pressure (maximal gradients: r = 0.96, SEE = 2; mean gradients: r = 0.97, SEE = 1.2). A close correlation between corresponding Doppler and catheter gradients also was found in patients with aortic prostheses (maximal gradients: r = 0.94, SEE = 6; mean gradients: r = 0.94, SEE = 3). Thus, continuous wave Doppler echocardiography can accurately predict the pressure gradient across prosthetic valves.

Aged↗

PubMed1989

Estimation and comparison of changes in the presence of informative right censoring: conditional linear model.

A general linear regression model for the usual least squares estimated rate of change (slope) on censoring time is described as an approximation to account for informative right censoring in estimating and comparing changes of a continuous variable in two groups. Two noniterative estimators for the group slope means, the linear minimum variance unbiased (LMVUB) estimator and the linear minimum mean squared error (LMMSE) estimator, are proposed under this conditional model. In realistic situations, we illustrate that the LMVUB and LMMSE estimators, derived under a simple linear regression model, are quite competitive compared to the pseudo maximum likelihood estimator (PMLE) derived by modeling the censoring probabilities. Generalizations to polynomial response curves and general linear models are also described.

Analysis of Variance↗

PubMed1989

Does exercise training alter myocardial creatine kinase MB isoenzyme content?

Skeletal muscle biopsies from highly trained endurance athletes have been shown to contain an increased percentage of the creatine kinase MB (CK-MB) isoenzyme, which has been attributed to continuous regeneration of the skeletal muscle fibers in response to exercise-induced injury. The purpose of this study was to determine whether myocardium undergoes a similar degenerative-regenerative process as a result of exercise training. Fifteen mongrel dogs underwent a 12-wk period of training (N = 8) or cage confinement (N = 7). The animals were then sacrificed, and samples of left and right ventricular myocardium were analyzed for total CK activity and CK-MB isoenzyme content. Percentages of CK-MB were slightly but insignificantly higher from both ventricles of exercise-trained as compared with cage-confined dogs: left ventricle, 4.6 +/- 0.6% vs 3.3 +/- 0.6%, respectively (P = 0.15); right ventricle, 4.0 +/- 0.4% vs 3.0 +/- 0.8%, respectively (P = 0.29). We conclude that chronic exercise training does not induce physiologically important degenerative changes in myocardium.

Animals↗

PubMed1988

Prediction of the severity of aortic stenosis by Doppler aortic valve area determination: prospective Doppler-catheterization correlation in 100 patients.

Two-dimensional and Doppler echocardiography was performed prospectively in 100 patients with aortic stenosis who were undergoing clinically indicated cardiac catheterization. The purpose of this study procedure was to determine various Doppler variables predictive of the severity of aortic stenosis and to compare Doppler- and catheterization-derived aortic valve areas. Doppler-derived mean gradient correlated well with corresponding gradient by catheterization (r = 0.86). Peak Doppler aortic flow velocity greater than or equal to 4.5 m/s and Doppler-derived mean aortic gradient greater than or equal to 50 mm Hg were specific (93 and 94%, respectively) for severe aortic stenosis (defined as catheterization-derived aortic valve area less than or equal to 0.75 cm2) but were not sensitive (44 and 48%, respectively). Doppler-derived aortic valve area calculated by the continuity equation correlated well with catheterization-derived aortic valve area calculated by the Gorlin equation when either the time-velocity integral ratio (r = 0.83) or the peak flow velocity ratio (r = 0.80) between the left ventricular outflow tract and the aortic valve was used in the continuity equation. A velocity ratio of less than or equal to 0.25 alone was sensitive (92%) in detecting severe aortic stenosis. Therefore, use of various Doppler-derived values allows reliable noninvasive estimation of the severity of aortic stenosis.

Aged↗