955 research outputs found
Cardiac Surgery in Octogenarians; Peri-Operative Outcome and Long-Term Results
AIMS: Because the elderly are increasingly referred for operation, we reviewed the results of cardiac surgery in patients of 80 years or older. METHODS AND RESULTS: Records of 182 consecutive octogenarians who had had cardiac operations between 1992 and 1998 were reviewed. Follow-up was 100% complete. Seventy patients had coronary grafting (CABG), 70 aortic valve replacement, 30 aortic valve replacement+CABG, and 12 mitral valve repair/replacement. Rates of hospital death, stroke, and prolonged stay (>14 days) were as follows: CABG: 7 (10%), 2 (2.8%) and 41 (58%); aortic valve replacement: 6 (8.5%), 2 (2.8%) and 32 (45.7%); aortic valve replacement+CABG: 8 (26.5%), 1 (3.8%) and 14 (46.6%); mitral valve repair/replacement: 3 (25%), 1 (8.3%) and 5 (41.6%). Multivariate predictors (P<0.05) of hospital death were New York Heart Association functional class, urgent procedure, prolonged cardiopulmonary bypass time, and, after aortic valve replacement, previous percutaneous aortic valvuloplasty. Ascending aortic atheromatous disease was predictive of stroke, while pre-operative myocardial infarction was predictive of prolonged hospital stay. Actuarial 5-year survival was as follows: CABG, 65.8+/-8.8%; aortic valve replacement, 63.6+/-7.1%; aortic valve replacement+CABG, 62.4+/-6.8%; mitral valve repair/replacement, 57.1+/-5.6%; and total, 63.0+/-5.6%. Multivariate predictors of late death were pre-operative myocardial infarction, and urgent procedure. Ninety percent of long-term survivors were in New York Heart Association class I or II, and 87% believed having a heart operation after age 80 years was a good choice. CONCLUSION: Cardiac operations are successful in most octogenarians with increased hospital mortality, and longer hospital stay. Long-term survival and quality of life are good
The quality of a registry based study depends on the quality of the data - without validation, it is questionable
Non peer reviewe
Effects of increased afterload on left ventricular performance and mechanical efficiency are not baroreflex-mediated
peer reviewedObjective: To assess baroreflex intervention during increase in left ventricular afterload, we compared the effects of aortic banding on the intact cardiovascular system and under hexamethonium infusion. Methods: Six open-chest pigs, instrumented for measurement of aortic pressure and flow, left ventricular pressure and volume, were studied under pentobarbital-sufentanil anesthesia. Vascular arterial properties were estimated with a four-element windkessel model. Left ventricular contractility was assessed by the slope of end-systolic pressure-volume relationship. Results: The effects of aortic banding on mechanical aortic properties were unaffected by autonomic nervous system inhibition. However, increase in peripheral arterial vascular resistance and in heart rate were prevented by hexamethonium. Aortic banding increased left ventricular contractility and stroke work. Left ventricular-arterial coupling remained unchanged, but mechanical efficiency was impaired. These ventricular changes were independent of baroreflex integrity. Conclusions: Our results demonstrate that an augmentation in afterload has a composite effect on left ventricular function. Left ventricular performance is increased, as demonstrated by increase in contractility and stroke work, but mechanical efficiency is decreased. These changes are observed independently of baroreflex integrity. Such mechanisms of autoregulation, independent of the autonomic nervous system, are of paramount importance in heart transplant patients. (C) 2003 Elsevier B.V. All fights reserved
Model-based cardiovascular monitoring of acute pulmonary embolism in porcine trials
Introduction:
Diagnosis and treatment of cardiac and circulatory dysfunction can be error-prone and relies heavily on clinical
intuition and experience. Model-based approaches utilising measurements available in the Intensive care unit
(ICU) can provide a clearer physiological picture of a patient’s cardiovascular status to assist medical staff with
diagnosis and therapy decisions. This research tests a subject-specific cardiovascular system (CVS) modelling
technique on measurements from a porcine model of acute pulmonary embolism (APE).
Methods:
Measurements were recorded in 5 pig trials, where autologous blood clots were inserted every two hours into
the jugular vein to simulate pulmonary emboli. Of these measurements only a minimal set of clinically available or
inferable data were used in the identification process (aortic and pulmonary artery pressure, stroke volume, heart
rate, global end diastolic volume, and mitral and tricuspid valve closure times).
The CVS model was fitted to 46 sets of data taken at 30 minute intervals (t=0, 30, 60, …, 270) during the induction
of APE to identify physiological model parameters and their change over time in APE. Model parameters and
outputs were compared to experimentally derived metrics and measurements not used in the identification
method to validate the accuracy of the model and assess its diagnostic capability.
Results:
Modelled mean ventricular volumes and maximum ventricular pressures matched measured values with median
absolute errors of 4.3% and 4.4%, which are less than experimental measurement noise (~10%). An increase in
pulmonary vascular resistance, the main hemodynamic consequence of APE, was identified in all the pigs and
related well to experimental values (R=0.68). Detrimental changes in reflex responses, such as decreased right
ventricular contractility, were noticed in two pigs that died during the trial, diagnosing the loss of autonomous
control. Increases in the ratio of the modelled right to left ventricular end diastolic volumes, signifying the
leftward shift of the intra-ventricular septum seen in APE, compared well to the clinically measured index
(R=0.88).
Conclusions:
Subject-specific CVS models can accurately and continuously diagnose and track acute disease dependent
cardiovascular changes resulting from APE using readily available measurements. Human trials are underway to
clinically validate these animal trial results
Comparison between single-beat and multiple-beat methods for estimation of right ventricular contractility.
OBJECTIVE: It was investigated whether pharmacologically induced changes in right ventricular contractility can be detected by a so-called "single-beat" method that does not require preload reduction. DESIGN: Prospective animal research. SETTING: Laboratory at a large university medical center. SUBJECTS: Eight anesthetized pigs. INTERVENTIONS: End-systolic elastance values obtained by a recently proposed single-beat method (Eessb) were compared with those obtained using the reference multiple-beat method (Eesmb). MEASUREMENTS AND MAIN RESULTS: Administration of dobutamine increased Eesmb from 1.6 +/- 0.3 to 3.8 +/- 0.5 mm Hg/mL (p =.001), whereas there was only a trend toward an increase in Eessb from 1.5 +/- 0.2 to 1.7 +/- 0.4 mm Hg/mL. Esmolol decreased Eesmb from 1.7 +/- 0.3 to 1.1 +/- 0.2 mm Hg/mL (p =.006), whereas there was only a trend for a decrease in Eessb from 1.5 +/- 0.2 to 1.3 +/- 0.1. CONCLUSIONS: The present method using single-beat estimation to assess right ventricular contractility does not work as expected, since it failed to detect either increases or decreases in right ventricular contractility induced by pharmacologic interventions.Peer reviewe
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