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G B Haasler

Publications and source records attributed to G B Haasler.

32 records · Page 2Linked to original sources
PubMed1987

Controlled reperfusion following regional ischemia.

The ability to reverse acute coronary occlusion with fibrinolytic agents and percutaneous transluminal angioplasty has increased interest in the revascularization of ischemic myocardium. This study defines changes in global ventricular function, mass, and compliance during acute coronary occlusion and following reperfusion with blood in the beating and arrested heart. In 17 dogs on cardiopulmonary bypass, the proximal left anterior descending coronary artery was occluded for 45 minutes. In 12 dogs, flow was reestablished by releasing the coronary snare in the beating heart. In the other 5 dogs, the snare was released during a continuous 10-minute infusion of blood potassium cardioplegia in the arrested heart. Coronary occlusion resulted in significant decreases in stroke work index and left ventricular (LV) mass, but compliance was unchanged. Reperfusion in the beating heart increased LV mass compared with the values measured before ischemia (104 +/- 5 versus 95 +/- 5 gm; p less than 0.05) and decreased LV compliance (39 +/- 4 versus 53 +/- 4 ml at LV end-diastolic pressure of 8 mm Hg; p less than 0.05). In contrast, with blood cardioplegia-based reperfusion in the arrested heart, LV mass and LV compliance remained unchanged from control values. We conclude that revascularization of acutely ischemic myocardium in the beating heart further impairs LV function by increasing LV mass and decreasing compliance. This damage can be avoided by reperfusion with blood cardioplegia in the arrested heart.

Animals↗
PubMed1987

Septic spondylodiscitis in ankylosing spondylitis.

A patient with ankylosing spondylitis (AS) for 10 years suddenly developed localized midback pain after minimal activity. Although he sought immediate medical assistance, recognition of a septic spondylodiscitis was delayed 3 weeks. One day after admission, he developed fever and admitted to intravenous drug use. Staphylococcus aureus empyema and spondylodiscitis were subsequently diagnosed. Clinical differentiation of aseptic from septic spondylodiscitis cannot be ignored in patients with AS.

Adult↗
PubMed1985

Compliance, mass, and shape of the canine left ventricle after global ischemia analyzed with two-dimensional echocardiography.

End-diastolic pressure (EDP)-volume (EDV) curves were constructed for the left ventricle (LV) in 10 dogs on cardiopulmonary bypass before and after 45 min of normothermic ischemic arrest. LVEDV and mass were calculated from three perpendicular two-dimensional echocardiographic sections using a Simpson's rule algorithm. The echocardiographic method employed was specially developed in earlier work for physiologic studies in dogs. Postmortem pressure-volume curves were measured for comparison by direct saline infusion into sealed ventricles. LVEDV was plotted against LVEDP (0-20 mm Hg) and data were analyzed by two-way analysis of variance and also by exponential curve fitting to the relation EDP = alpha e beta EDV, where beta is the derived exponential constant reflecting slope and thereby ventricular stiffness. Postischemic EDP-EDV curves shifted to the left and the beta constant increased (beta = 0.02 +/- 0.005 (SE) vs 0.05 +/- 0.01, P less than 0.05). LV eccentricity, the ratio between long- and short-axis measurements, was unchanged (1.43 +/- 0.05 vs 1.46 +/- 0.06 postischemia, NS), but LV mass increased (105 +/- 7 vs 128 +/- 9 g postischemia, P less than 0.001). Postischemic LV mass by echo was not significantly different from measured postmortem LV mass (r = 0.87). The nonparallel alteration in the EDP-EDV curves, lack of change in LV shape (eccentricity), and increase in LV mass in the postischemic ventricle suggest that increased ventricular stiffness rather than direct encroachment by the edematous endocardium on chamber volume is responsible for postischemic changes in LV diastolic properties.

Animals↗
PubMed1985

Effects of simulated clinical cardiopulmonary bypass and cardioplegia on mass of the canine left ventricle.

Myocardial edema is a well-documented response to ischemia and reperfusion in dogs and can be detected as an increase in left ventricular (LV) mass measured echocardiographically. Investigation in human beings has failed to demonstrate similar increases in LV mass after routine cardiac operations. However, direct comparison of these observations is not possible, because dogs have not been studied under conditions of cardiopulmonary bypass (CPB) and global ischemia that rigorously reproduce those of a clinical operation. Accordingly, clinical CPB and global ischemia were simulated in 8 adult dogs. Multisection two-dimensional echocardiograms and a computerized light pen were used to calculate LV volume and mass. The data were analyzed during four periods: before CPB; CPB before cross-clamping; CPB after cross-clamping, and after CPB. Echocardiographic LV mass increased significantly from 89.5 +/- 7.4 gm (before CPB) to 94.6 +/- 8.5 gm (CPB before cross-clamping) (p less than 0.05) and from 94.6 +/- 8.5 gm to 100.4 +/- 8.1 gm (CPB after cross-clamping) (p less than 0.05). Overall, mass increased 13.9% (p less than 0.05). Mean wall thickness increased 0.08 cm (p less than 0.05) overall and correlated with the increase in mass (r = 0.79). Postmortem mass correlated well with late echocardiographic mass (r = 0.95). Interobserver correlation of 98 separate mass determinations was high (r = 0.84) with a coefficient of variation of 10.5%. We conclude that canine LV mass increases significantly with CPB and global ischemia maintained within clinical standards and that human beings and dogs may differ in extent of edema during CPB.

Animals↗
PubMed1985

Two-dimensional echocardiography in dogs. Variation of left ventricular mass, geometry, volume, and ejection fraction on cardiopulmonary bypass.

Quantitative two-dimensional echocardiography was evaluated in 39 open-chest dogs placed on cardiopulmonary bypass. The correlation coefficient of left ventricular end-diastolic volume against postmortem pressure-volume curves was r = 0.89 to 0.93 (347 measurements in 15 dogs, 0 to 24 mm Hg). Ejection fraction was validated against roller pump flow and echo left ventricular end-diastolic volume (r = 0.83, n = 13). Left ventricular mass in vivo was compared with postmortem left ventricular mass (r = 0.81 in 21 early studies, r = 0.91 in 10 later studies with updated equipment) and was found to increase with ischemic injury as well as cardiopulmonary bypass with hemodilution. Left ventricular mass increased (p less than 0.001) from 119 +/- 5 (standard error of the mean) to 138 +/- 6 gm (n = 23) after 2 1/2 hours on cardiopulmonary bypass and moderate hemodilution. With the addition of ischemic arrest, left ventricular mass increased from 119 +/- 7 to 148 +/- 11 gm (p less than 0.01, n = 8), and myocardial water content increased by 2.0% +/- 0.4%, which accounted for at least 65% of the observed mass change. Mean left ventricular wall thickness increased from 13.8 to 15.5 mm (p = 0.02) after ischemia. Ventricular shape became more spherical with increasing left ventricular end-diastolic pressure. We conclude that two-dimensional echocardiography can be reliably used for accurate, serial measurements in physiological studies. The demonstrated variability in left ventricular mass is important, yet frequently ignored. Recognizing left ventricular mass changes may facilitate the detection of myocardial injury reflected as edema.

Animals↗
PubMed1984

Heart-rate effects on canine left-ventricular end-diastolic compliance measured by two-dimensional ultrasound.

Despite recent interest in left ventricular (LV) compliance during open-heart surgery, the effect of heart rate (HR) remains unclear due to technical limitations of previous studies. In the presence of Formalin-induced complete atrioventricular (AV) block, AV sequentially paced heart rate was varied between 100, 125, and 150 beats/min in eight dogs on cardiopulmonary bypass. The heart was cradled in an open pericardial well filled with ultrasound-conducting gel. LV end-diastolic pressure (LVEDP) was varied over 0-20 mm Hg by flow regulation in the bypass circuit. Left ventricular end-diastolic volume (LVEDV) was calculated from three orthogonal two-dimensional (2-D) echocardiographic sections using Simpson's rule. Exponential curves derived from the relation LVEDP = ke(bxLVEDV) demonstrated a small, but significant increase in the mean exponential constants (b = 0.034, 0.037, and 0.049 at HR 100, 125, and 150, respectively) reflecting progressive stiffening with increasing heart rate. However, mean overall pressure-volume relations were not significantly altered when analyzed in four separate intervals of LVEDP. It is concluded that although LV volume determinations with 2-D echocardiography demonstrate a steady trend toward decreased end-diastolic LV compliance with increasing rate, this change is so small as to make heart rate a minor determinant of observed intraoperative compliance changes.

Animals↗
PubMed1984

Effect of cardiopulmonary bypass and global ischemia on human and canine left ventricular mass: evidence for interspecies differences.

Previous studies in dogs suggest that global ischemia with cardiopulmonary bypass causes increased left ventricular (LV) mass and water content. To investigate effects in humans, we developed a simplified method for mass determination by intraoperative two-dimensional echocardiography. LV mass was measured as echocardiographic short-axis myocardial area. This was validated by linear regression versus postmortem LV mass in 10 dogs (r = 0.89) and versus single-plane angiography in 18 patients (r = 0.73). According to this method, there was no change in LV mass (209 gm versus 208 gm; NS) at constant preload in 20 patients during routine operations (eight coronary revascularizations, 10 aortic valve replacements, and two mitral valve replacements). The same method used in 10 dogs after 2 hours of bypass, 60 minutes of normothermic global ischemia, and reperfusion revealed an LV mass increase from 113 +/- 13 gm (SE) to 150 +/- 16 gm (p less than 0.01) at matched preload. In addition, in 14 dogs after 2 hours of bypass alone, LV mass was unchanged (98 +/- 5 gm versus 101 +/- 5 gm; NS) at matched preload. Data recently derived from a separate study in our laboratory revealed a statistically significant increase in canine LV mass when conditions of human cardiopulmonary bypass and cardioplegic arrest were reproduced. We conclude that uncomplicated cardiac operations in humans do not alter LV mass. This supports the safety of crystalloid cardioplegia in humans. While present evidence is not conclusive, it appears that the threshold for edema formation after ischemic injury may be higher in humans than it is in dogs. The clinical relevance of studies of cardioplegia in edematous dog hearts thus deserves careful scrutiny.

Animals↗
PubMed1984

Pharmacologic antagonism of propranolol in dogs. III. Effects of dopamine-isoproterenol and glucagon on hemodynamics and myocardial oxygen consumption in ischemic hearts during chronic propranolol administration.

In 31 dogs chronically beta blocked with oral propranolol (12 to 14 mg/kg/day), glucagon (20 micrograms/kg) and combined dopamine (10 micrograms/kg/min) and isoproterenol (0.2 micrograms/kg/min) were given intravenously and tested for hemodynamic efficacy. Dogs were divided into four groups. Basal hemodynamics were obtained In Group I (n = 8) without cardiopulmonary bypass. In Group II (n = 8), hemodynamics were studied after 15 minutes of global ischemia during cardiopulmonary bypass. In Group III (n = 8), hemodynamics were studied after regional ischemia produced by ligation of the proximal left anterior descending coronary artery. In Group IV (n = 7), myocardial oxygen consumption and left ventricular mechanics were studied before and after 1 hour of cardiopulmonary bypass. Our results indicate the following: (1) Dopamine-isoproterenol improves hemodynamics in basal, post-global ischemic, and post-regional ischemic states. Glucagon improves hemodynamics either insignificantly or to a lesser extent than dopamine-isoproterenol. Furthermore, glucagon produces a larger increase in heart rate, which is not desirable. (2) Both dopamine-isoproterenol and glucagon increase myocardial oxygen consumption in comparison with control.

Animals↗
PubMed1982

Intraoperative 2-dimensional echocardiography: ejection of microbubbles from the left ventricle after cardiac surgery.

Although the presence of entrapped air in the left ventricle at surgery has long been a concern, its prevalence and clinical significance are unknown. Two-dimensional echocardiography provides a unique means for observing intracardiac microbubbles intraoperatively. Accordingly, intraoperative 2-dimensional echocardiograms obtained in 79 patients immediately after cardiopulmonary bypass were examined for the presence of microbubbles. Left ventricular microbubbles were detected in 14% of coronary artery bypass operations (n = 22), 50% of multiple valve replacements (n = 8), 67% of single valve replacements (n = 58), and 100% of atrial septal defect closures (n = 4), left atrial myxoma resections (n = 2), and mitral commissurotomies (n = 2). Microbubbles were not observed in patients undergoing coronary artery bypass with valve replacement (n = 4) or with removal of left ventricular aneurysm (n = 1). Continuous ejection of microbubbles from the left ventricle was frequently noted for extended periods of time and, although no patient in this study showed evidence of gross neurologic dysfunction, the possibility of subclinical organ damage exists. We conclude that 2-dimensional echocardiography is useful for detection of intracardiac microbubbles and therefore may be instrumental in their elimination.

Cardiac Surgical Procedures↗
PubMed1982

The absence of temperature effects on end-diastolic pressure-volume relations in the canine left ventricle determined by two-dimensional echocardiography.

Because of divergent conclusions in the literature regarding the effects of temperature on end-diastolic compliance in the canine left ventricle (LV), pressure-volume relationships at normothermia and hypothermia (28 degrees C) were studied with two-dimensional ultrasound in nine dogs on cardiopulmonary bypass (open pericardium) over a range of left ventricular end-diastolic pressure (LVEDP) from 0 to 22 mm Hg. Three perpendicular echocardiographic sections were used with Simpson's rule to measure LV volume and mass at end-diastole for each level of LVEDP. Temperature was varied between 37 degrees and 28 degrees C by systemic cooling, and heart rate was allowed to slow spontaneously with temperature reduction. There was no change in left ventricular end-diastole pressure-volume (LVEDP-LVEDV) relationships at lower temperature provided that ventricular relaxation was complete at end-diastole. In addition, serial postmortem pressure-volume curves carried out by direct saline infusion into sealed ventricles at 38 degrees and 28 degrees C in three additional dogs demonstrated no temperature effects on postmortem LV compliance. Postmortem mass correlated well with echocardiographically determined LV mass, which showed a significant increase during the period of cardiopulmonary bypass, correlating with the development of myocardial edema. In summary, there appears to be no effect of moderate hypothermia on LVEDP-LVEDV relationships, provided the heart is in true diastasis at end-diastole. In addition, echocardiographic techniques can be used to study LV mass change on cardiopulmonary bypass.

Animals↗
PubMedDate not supplied

Self-selected walking velocity for functional ambulation in patients with end-stage emphysema.

PURPOSE: Considerable attention has been given to ambulation and dyspnea in the population with chronic obstructive pulmonary disease; however, previous studies leave the question of what constitutes functional ambulation in this population unanswered. This article examines ambulation for functional independence in the community for patients with-end-stage emphysema based on their self-selected walking velocity (SSWV) during a 6-minute walk (6 MW) and a timed get up and go (GUG) test. METHODS: Fifty-nine patients (28 women, 31 men; mean age of 65.1 +/- 7.2 years) referred for lung transplantation or lung volume reduction surgery (mean forced expiratory volume in 1 second [FEV1] of 0.60 +/- 0.20 L; mean FEV1 as percent of predicted [FEV1%] of 22.7 +/- 8.7%) each had a 6 MW and GUG test performed on the same day. Calculations for SSWV and estimated energy expenditure were determined using the horizontal walking formula by the American College of Sports Medicine. RESULTS: No statistically significant gender differences were identified for distance walked (235.1 +/- 92.0 m), rest time taken (33.2 +/- 58.5 seconds), actual walk time (5.5 +/- 1.0 minutes), or SSWV (42.2 +/- 13.9 m/min or 1.6 +/- 0.5 miles per hour) during the 6 MW. Men tended to walk farther and faster but rested more. The SSWV during the GUG test was similar (mean 41.8 +/- 10.9 m/min or 1.6 +/- 0.4 miles per hour) to the SSWV during the 6 MW. Estimated energy expenditure was approximately 1.6 to 3.4 metabolic equivalents (METS; mean 2.3 +/- 0.5 METS). CONCLUSION: The literature defines independent community ambulation as the ability to walk at least 332 m at a near-normal velocity of approximately 80 m/min. This study population was significantly impaired for both distance and the velocity required to ambulate independently in the community. Documentation of both rest time and walk time taken during a 6 MW test will enable SSWV to be calculated and interpreted as it relates to independent community ambulation.

Aged↗