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C H Edmonds

Publications and source records attributed to C H Edmonds.

14 recordsLinked to original sources
PubMed1978

Molecular, microscopic, microstructural and mechanical methods of analyzing pseudoneointimal linings within partial artificial hearts in man and the calf.

Ex vivo molecular, microscopic (cellular), microstructural and mechanical methods have been utilized to evaluate biologic, blood-interfacing linings (pseudoneointimal) formed on textured, fibril-flocked pumping surfaces within abdominal left ventricular assist devices (ALVADs) on partial artificial hearts. Thus far, seventeen human and twenty bovine pseudoneointimal linings (1--28 day pumping durations) have been evaluated by these methods. The results indicate that pseudoneointima begins developing within 24 hours after contact of the pumping surface with blood and is well developed at five days. The linings exhibit surface immunofluorescent fibrinogen activity, viable surface macrophages and histiocytes and scattered erythrocytes at ALVAD removal. Structurally similar linings (20 micrometer to 500 micrometer in thickness) develop in calves and in man. Mechanically, pseudoneointima is a stable, adherent, highly compliant, isotropic structural material. It is linearly elastic and strain-rate independent, with small viscous energy losses under physiologic strains. The methods employed for the evaluation of pseudoneointima provide useful information to determine the suitability of textured or rough surfaces for blood interfacing. The cumulative results indicate that the textured surface approach is useful for intermediate-term clinical ALVAD utilization.

Animals↗
PubMed1978

Intra-aortic balloon pumping: theory and practice. Experience with 325 patients.

Intra-aortic balloon pumping to support the failing circulation is now an accepted therapeutic modality. The device is simple. Insertion can be accomplished rapidly and efficiently in emergency rooms, coronary care units, cardiac catheterization suites and operating rooms, preoperatively, intraoperatively and postoperatively. The hemodynamic effects are immediate and predictable, and the accruing clinical results show increasing survival and hospital discharge rates. In these institutions, mechanical support of the circulation by this and more advanced methods has been formalized within the responsibility of a Circulatory Support Service. The purpose of this report is to summarize some observations and analyses which have been made during care of 325 consecutive postcardiotomy and/or postinfarction cardiogenic shock patients. Historical, theoretical, basic, and applied aspects and current results are included. Foremost are the straightforward concepts of considering the heart as a pump, the failing heart as a failing pump and intra-aortic balloon pumping as a temporary intravascular, auxiliary pump, capable of stabilizing or reversing that failure if utilized early in its evolution.

Adult↗
PubMed1977

An intracorporeal (abdominal) left ventricular assist device. Initial clinical trials.

We have initiated clinical trials with an intracorporeal (abdominal) partial artificial heart and ten preterminal postcardiotomy patients have been studied. During profound left ventricular failure, the device captures the entire cardiac output from the apex of the left ventricle at low pressures (20 to 40 mm Hg) and ejects (at 80 to 150 mm Hg) into the infrarenal abdominal aorta; the biological aortic valve opens only intermittently and the entire systemic circulation is pump generated. The device is six to ten times more effective than intra-aortic balloon pumping in man and has maintained systemic perfusion during clinical asystole and ventricular fibrillation. We have documented that the profoundly depressed postcardiotomy left ventricle, initially incapable of ejection, can recover during total left ventricular unloading with the abdominal left ventricular assist device support over a seven-day period.

Abdomen↗
PubMed1977

Failure of general anesthesia to potentiate propranolol activity.

To determine whether halothane and morphine, commonly used during anesthesia for cardiac operations, potentiate the beta blocking activity of propanolol, hemodynamic changes induced by five incremental doses of propranolol (10, 20, 50, 120, 200 microgram/kg) were measured during halothane, 1 per cent, in oxygen, and morphine, 4 mg/kg. Against a background of contant beta stimulation by infusion of isoproterenol, 0.1 microgram/kg/min, and vagal blockade by atropine, 3 mg, propranolol produced significant dose-related decreases in heart rate, cardiac index, stroke volume index, and left ventricular dp/dtmax and significant increases in mean aortic pressure, systemic vascular resistance, and pulmonary capillary wedge pressure. Compared with basal anesthesia with pentobarbital, 15 mg/kg, neither morphine nor halothane increased sensitivity to any measured effect of propranolol expressed as the slope of the log dose-response relationship. It is concluded that the beta blocking activity of propranolol is not potentiated by morphine and halothane anesthesia but, rather, their effects are additive.

Anesthesia, Intravenous↗
PubMed1977

Prognostic indices for survival during postcardiotomy intra-aortic balloon pumping. Methods of scoring and classification, with implications for left ventricular assist device utilization.

To define more clearly a salvageable patient for possible utilization of a left ventricular assist device prior to multiple organ failure and irretrievability during postcardiotomy intra-aortic balloon pumping (IABP), we made prospective and retrospective analyses to determine prognostic indices for survival. Serial left ventricular function curves (IABP on-off), scoring methods, hemodynamic and renal function tracking trajectories, survival versus nonsurvival data envelopes, and classification methods were developed and used. All patients requiring postcardiotomy IABP support who were in Class A survived; 80 percent of the patients in Class B survived. All patients who remained in Class C for 12 hours or more following operation with IABP support died. These preliminary analyses suggest that the postcardiotomy IABP-supported patient with a score of less than 6 who remains in Class C for 12 hours or more is at the highest possible risk and is a probably candidate for more effective support with a left ventricular assist device.

Assisted Circulation↗
PubMed1976

Production of controlled reversible left ventricular failure in calves using intracoronary lidocaine hydrochloride: a useful method of evaluating left ventricular assist devices.

The experimental production of stable, controlled, short-term left ventricular failure is valuable in the evaluation of implantable circulatory support systems. Acute or chronic left ventricular failure produced by occlusion or embolization of coronary arteries results in muscle dysfunction and degrees of failure that may be difficult to control. The effects of varying amounts of intracoronary lidocaine were studied during short- and long-term evaluations of intracorporeal left ventricular assist pumping. In 8 Hereford calves the left main coronary artery was cannulated with an intracoronary catheter in open and closed chest preparations. Dose-related negative inotropic effects were noted when lidocaine was injected at individual doses of 50, 75, and 100 mg. Following 100 mg doses, mean aortic pressure, cardiac output, and maximum rate of rise of left ventricular pressure decreased; left ventricular end-diastolic pressure increased fourfold. Similar effects were noted with short continuous infusions of lidocaine. The initial responses to injection or continuous infusions, if effective, were noted within 40 to 60 seconds. Several episodes of failure could be produced with either method following recovery periods of 10 to 15 minutes. In all instances, actuation of a left ventricular assist device immediately reversed the hemodynamic effects of the pharmacologically induced failure.

Animals↗
PubMed1975

Dynamic alveolar mechanics as studied by videomicroscopy.

The in vivo morphology of rat alveoli has been recorded and studied on videotape. The dynamic internal structure has been compared to that observed by histologic section from lung rapidly frozen with liquid nitrogen. The irreversible nature of local alveolar wall movement has been demonstrated in animals ventilated both with and without positive end-expiratory pressure (10 cm water) by parametrically comparing the distances between two sets of paired points measured sequentially across internal alveolar surfaces at intervals of 0.017 sec. Geometric hysteresis was significantly less in the animals ventilated with positive end-expiratory pressure. This hysteresis can be explained by irreversibility in alveolar surface area apart from any irreversible dependence on surface tension. Sharp reverses and rapid changes in geometric hysteresis suggest that the length-tension properties of elastic tissue within the alveolar wall and interface forces from adjacent alveoli are important determinants of local alveolar wall motion and pulmonary hysteresis.

Animals↗
PubMed1975

Evaluation of cardiac function and venous return curves in awake, unanesthetized cialves with an implanted total artificial heart.

1) The implanted TAH offers a method of evaluating the effects of varying physiologic demands cardiac output and venous return. 2) Cardiac output and venous return measurements offer a method of evaluating system design of the device and driving and control-logic improvements in awake, unanesthetized animals. 3) The obtained cardiac function and venous return curves suggest that the present TAH is less responsive to increases in right atrial pressure than the natural heart, but is still completely controlled by venous return. Therefore, it is extremely important to make every effort to eliminate any factor causing excessive venous return.

Animals↗