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Biomedical subjects

L Golding

Publications and source records attributed to L Golding.

At least 19 recordsLinked to original sources
PubMed1991

Retrospective analysis of patients undergoing one- or two-stage strategies for myocardial revascularization and implantable cardioverter defibrillator implantation.

Internal defibrillation leads were placed at time of coronary revascularization in 79 patients. In 34, an implantable cardioverter defibrillator (ICD) was placed simultaneously (group I). A two-stage strategy (selective implantation of the ICD in patients with postoperative spontaneous or inducible ventricular tachycardia [VT]) was followed in 45 patients (group II). Group I patients had failed more antiarrhythmic drug trials (2.9 +/- 1.6 vs 1.5 +/- 1.6; P = 0.02), including amiodarone (62% vs 20%; P less than 0.001). There were four operative deaths in each group. Postoperatively, VT was present in 27 group II patients (60%), 25 of whom received an ICD (two refused device implantation). Patients with postoperative VT had a lower left ventricular ejection fraction than those without VT (33 +/- 9 vs 47 +/- 16; P = 0.01). Actuarial survival at 1, 2, and 3 years was 88 +/- 6, 88 +/- 7, and 88 +/- 10 in group I; and 83 +/- 6, 76 +/- 7, and 76 +/- 11 in group II (NS). No patient without an ICD (based on the postoperative electrophysiological study [EPS]) died suddenly. Five patients (6%) had ICD system infection. Sudden death was largely prevented by either strategy, but relatively high rates of operative mortality and ICD system infection were observed. Prospective studies should identify patients more likely to benefit from one or another strategy.

Aged↗
PubMed1990

Long-term outcome of unsuccessful percutaneous transluminal coronary angioplasty.

We analyzed the long-term outcome of 198 patients after unsuccessful percutaneous transluminal coronary angioplasty. Forty-nine percent underwent emergency coronary artery bypass grafting surgery, 17% had elective bypass surgery, and 34% were treated medically. The in-hospital mortality rate was 4%, and myocardial infarction occurred in 36% of patients. Follow-up was completed in 100% of patients with a mean follow-up period of 35 +/- 22 months. Actuarial cardiac survival at 4 years was 97% in the emergency bypass surgery group, 100% in the elective bypass surgery group, and 86% in the medically treated group. Actuarial event-free survival (freedom from myocardial infarction, bypass surgery, coronary angioplasty, and cardiac death) at 4-year follow-up was 81% in 198 patients, 90% in the emergency bypass surgery group, 85% in the elective bypass surgery group, and 65% in the medically treated group. Results of multivariate analysis showed that emergency or elective bypass surgery after failed coronary angioplasty, normal or mildly impaired left ventricular function, and male sex were predictors of better outcome at 4 years.

Actuarial Analysis↗
PubMed1986

Verification of Fourier phase and amplitude values from simulated heart motion using a hydrodynamic cardiac model.

Using pusher-plate-type artificial hearts, changes in the degree of synchrony and stroke volume were compared to phase and amplitude calculations from the first Fourier component of individual-pixel time-activity curves generated from gated radionuclide images (RNA) of these hearts. In addition, the ability of Fourier analysis to quantify paradoxical volume shifts was tested using a ventricular aneurysm model by which the Fourier amplitude was correlated to known increments of paradoxical volume. Predetermined phase-angle differences (incremental increases in asynchrony) and the mean phase-angle difference calculated from RNAs showed an agreement of -7 degrees +/- 4.4 degrees (mean +/- SD). A strong correlation was noted between stroke volume and Fourier amplitude (r = 0.98; P less than 0.0001) as well as between the paradoxical volume accepted by the 'aneurysm' and the Fourier amplitude (r = 0.97; P less than 0.0001). The degree of asynchrony and changes in stroke volume were accurately reflected by the Fourier phase and amplitude values, respectively. In the specific case of ventricular aneurysms, the data demonstrate that using this method, the paradoxically moving areas may be localized, and the expansile volume within these regions can be quantified.

Fourier Analysis↗
PubMed1985

Anatomical considerations in the design of a long-term implantable human left ventricle assist system.

A permanently implantable left ventricle assist system (LVAS) is being developed and is planned to be implanted in the left chest cavity against the chest wall with the electrohydraulic energy converter placed in a resected rib space. The inflow and outflow pump ports are connected to the left ventricle (LV) apex and to the descending aorta, respectively. Three additional major components of this system consist of the transcutaneous energy transmission system (TETS) (Thermedics), the variable volume device (VVD), and the internal battery. To finalize the design of this integrated system, key anatomical information was obtained by a special radiographic and angiographic study of 31 adult men with a varying degree of coronary artery disease and myocardial dysfunction. These data were combined with the previous computed tomography study by using a standard vertical reference system. The resultant integrated data, which consist of the three-dimensional chest model, the LV apex and axis orientation, rib orientation, chest wall thickness, and the descending aorta location, were used to define the design and anatomical locations of the inflow and outflow pump ports, the VVD, the pump and energy converter orientation, the TETS, and the internal battery. The most critical component for the design was found to be the inflow system. With regard to the average coronary disease patient, an anatomically practical configuration was demonstrated to exist for the presently proposed LVAS. Design flexibility was allowed for some of the critical components in order to fit the system in a large number of patients regardless of the stage and type of the underlying disease.

Adult↗
PubMed1985

Experimental evaluation of complete electrically powered ventricular assist system.

The LVAS utilizing an intrathoracic blood pump and a parathoracic, electrohydraulic energy converter has a number of promising features. These include: transcutaneous energy transmission and an implanted variable volume device which eliminate the need for percutaneous access; utilization of an intrathoracic blood pump and variable volume device which allow the diaphragm and abdominal cavity to remain intact; parathoracic or subcutaneous location of the transformer secondary, energy converter, internal battery and interconnecting elements allowing replacement with a minor surgical procedure; employment of the "biolized" continuous blood contacting surface which has the potential of long-term use without anticoagulants and utilization of an electrohydraulic energy converter which provides synchronization without requiring transducers and associated electronics and which provides lubrication of mechanical components. The development effort, which began separately in 1977 and has been conducted jointly by Nimbus and the Cleveland Clinic since 1980, has demonstrated that the above features can be incorporated in a reliable LVAS. In particular, the system in vivo test series have demonstrated the soundness of the basic concepts and led to refinements which were demonstrated in the 6-1/2 mo test. All elements of the system have been utilized during the in vivo test program. Component tests of significance include: LVAS and total heart blood pump in vivo experiments of up to 7 mos duration which demonstrate the blood compatibility of the biolized surface without the use of long-term anticoagulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Initial in vivo tests of an electrohydraulic actuated total artificial heart.

The authors are involved in developing a total artificial heart (TAH) for permanent human use. This device was designed to fit human anatomy, and it has housings made of carbon fiber-epoxy composite and titanium. Tissue valves and protein coating of blood contacting surfaces minimize the need for anticoagulants. A continuously reciprocating electrohydraulic actuator is packaged between two alternately ejecting and passively filling ventricles. The control system varies the pump rate to maintain average left ventricular filling at 90%. This TAH in vivo successively progressed through 1, 5, 9, and 45 day implants in calves of 84, 94, 82, and 82 kg preoperative body weights. The operating modes include automatic and fixed rate. The chronic and acute effects of varying the right pump displaced stroke volume indicated the need for it to be limited to 85% of that of the left for stable hemodynamics at maximum flow. The pump exhibited afterload insensitive and preload sensitive performance. Pump output ranged from 4.0-9.5 L/min at left atrial pressures of 7-16 mmHg at pump rates of 80-160 beats/min in these four experiments. These data suggest that this device will meet clinical hemodynamic requirements; it has the potential for total implantable cardiac replacement.

Animals↗
PubMedDate not supplied

Development of the E4T electrohydraulic total artificial heart.

A completely implantable total artificial heart (TAH) is being developed based on many years of research performed at the Cleveland Clinic Foundation and Nimbus, Inc. The pumping unit consists of biolized surface-treated pusher plate blood pumps powered by an interventricular electrohydraulic energy converter. A variable volume device references the back side of the pusher plates to lung pressure. Electrical power is supplied by a transcutaneous energy transmission system, integrated with a wearable external battery pack. An implanted internal battery provides back-up power. System design and optimization efforts have resulted in a compact pumping unit package and an overall TAH that meets anatomic, physiologic, and engineering requirements. Overall pumping unit basic dimensions are 98 mm diameter and 80 mm thick. The blood pumps have a truncated conical shape and are separated by a thin interventricular septum 21 mm thick. Theoretical stroke volume is 64 ml, and maximum stroke length is 13.2 mm. Normal pump operation is at 90% of full stroke, which yields a net output of 53 ml, with valve regurgitation taken into account.

Cardiac Output↗