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Biomedical subjects

J M Moran

Publications and source records attributed to J M Moran.

At least 55 records · Page 3Linked to original sources
PubMed1986

Use of a counterpulsation balloon as a substitute for the pulmonic valve: a new application.

An inflatable, 3-ml balloon positioned within the distal right ventricular outflow tract was used to restore pulmonic valve function in 8 dogs that had undergone open-chest valvectomy. Balloon inflation and deflation were accomplished with a counterpulsation console. Valvectomy produced loss of the pulmonic incisura, a decrease in pulmonary artery diastolic pressure (PADP; mean +/- standard error) (9.5 +/- 1.3 versus 4.4 +/- 0.6 mm Hg, p less than 0.01), and an increase in pulmonary artery pulse pressure (PAPP) (8.6 +/- 0.7 versus 19.1 +/- 1.9 mm Hg, p less than 0.01) without significantly affecting forward cardiac output (CO) (1,750 +/- 110 versus 1,880 +/- 230 ml/min, p is not significant). Properly timed counterpulsation restored the pulmonic incisura, raised the PADP from 6.1 +/- 0.8 to 9.5 +/- 0.8 mm Hg (p less than 0.01), lowered the PAPP from 15.1 +/- 1.4 to 10.6 +/- 1.0 mm Hg (p less than 0.01), and raised the forward CO from 1,850 +/- 260 to 1,920 +/- 260 ml/min (p less than 0.01). The injection of glass beads, 40 to 150 microns in diameter, into the right ventricular outflow tract increased pulmonary vascular resistance from 383 +/- 87 to 730 +/- 150 dyne . sec cm-5 (p less than 0.05) and decreased forward CO from 1,850 +/- 260 to 1,570 +/- 230 ml/min (p less than 0.05). Following this injection, counterpulsation again restored the pulmonic incisura, raised the PADP from 9.3 +/- 1.4 to 16.0 +/- 1.8 mm Hg (p less than 0.01), lowered the PAPP from 25.0 +/- 2.5 to 18.2 +/- 2.5 mm Hg (p less than 0.01), and raised the forward CO from 1,570 +/- 230 to 1,720 +/- 220 ml/min (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

An eight-year experience with porcine bioprosthetic cardiac valves.

A total of 589 porcine bioprostheses were implanted in 509 patients from January, 1976, through December, 1983. Of the valves implanted, 390 were Hancock and 199 were Carpentier-Edwards. A total of 1,633 patient-years was accrued, with a mean follow-up of 38 months per patient. Two hundred eight patients had aortic valve replacement, 209 had mitral valve replacement, and 79 had multiple valve replacements, of which 46 were aortic and mitral replacements. The mortality for isolated aortic valve replacement was 5.8%; for isolated mitral replacement, 8.6%, and for all patients, 10.9%. Late mortality was 3.9% per patient-year. The actuarial survival rate at 5 years was 79% for aortic, 68% for mitral, and 76% for aortic-mitral valve replacement. There were 12 thromboembolic events (0.73% per patient-year). Two episodes occurred in patients with an aortic bioprosthesis, nine in patients with a porcine mitral valve, and one in a patient with mitral and tricuspid bioprosthetic valves. The probability of remaining free of thromboembolism at 5 years was 99% for the group having aortic valve replacement, 93% for those having mitral replacement, and 100% for the group having aortic-mitral valve replacements. Thirteen episodes of endocarditis occurred (0.8% per patient-year). Seven of the 13 patients died as a direct result of endocarditis. The probability of remaining free of prosthetic endocarditis at 5 years was 97% for the aortic valve replacement group, 95% for the mitral group, and 97% for the aortic-mitral group. There were 20 instances of xenograft failure (1.2% per patient-year). The probability of remaining free of valve failure at 5 years was 96% for the aortic valve replacement group, 93% for the mitral group, and 93% for the aortic-mitral replacement group. Primary tissue failure of a prosthesis occurred in seven patients, all with Hancock valves (0.43% per patient-year). As yet there has been no primary tissue failure of the Carpentier-Edwards prosthesis. There also appears to be a lower incidence of thromboembolism (Edwards, 0.3% per patient-year; Hancock, 0.8% per patient-year) and endocarditis (Edwards, 0.6% per patient-year; Hancock, 1.0% per patient-year). The low incidence of complications with the porcine bioprosthetic valve, especially the Carpentier-Edwards, encourages us to recommend its continued use, especially in situations in which anticoagulation is contraindicated.

Adult↗
PubMed1986

Trendelenburg versus PASG application--hemodynamic response in man.

Diminished venous return is the primary determinant of reduced cardiac output in hemorrhagic hypoperfusion. In this study the hemodynamic response of two therapies commonly employed to increase venous return in hemorrhagic hypoperfusion--pneumatic antishock garment (PASG) application and Trendelenburg (TREND) positioning--were compared in normovolemic man. Five patients had PASG pressure of 20 mm Hg compared with 10 degrees Trendelenburg, eight patients had 20 and 40 mm Hg PASG application compared with 10 degrees Trendelenburg. PASG application at both 20 and 40 mm Hg resulted in a significant increase in CVP (11.1 +/- 1.9 baseline to 16.0 +/- 2.7 PASG 40; p less than 0.01) left atrial pressure (LAP) (10.1 +/- 1.3 baseline to 14.4 +/- 1.8 PASG 20; p less than 0.01) pulmonary capillary wedge pressure (PCWP) (11.6 +/- 2.0 baseline to 16.8 +/- 3.4 PASG 40; p less than 0.01) and esophageal pressure (Pes) (5.0 +/- 0.8 baseline to 8.6 +/- 0.9 PASG 40; p less than 0.01). However, transmural right and left atrial pressure (RATP, LATP) and cardiac index (CI) were unchanged. Ten degrees of Trendelenburg resulted in no increase in CVP, PCWP, RATP, or LATP, but CI (2.67 +/- 0.07 baseline to 2.82 +/- 0.1 TREND; p less than 0.01) was significantly increased. Systemic vascular resistance index (570 +/- 46 TREND vs. 668 +/- 53 PASG 40; p less than 0.01) was significantly less in Trendelenburg compared to PASG at 40 mm Hg. The data demonstrate that elevation in CVP, LAP, and PCWP following PASG application is secondary to an increase in intrathoracic pressure (as measured by Pes).(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1985

Endocardial activation mapping and endocardial pace-mapping using a balloon apparatus.

The relation between endocardial activation mapping and endocardial pace-mapping was evaluated in 8 dogs while they were on cardiopulmonary bypass. Pacing or recording was accomplished by using a balloon apparatus (with 32 bipolar electrodes) inserted through a left apical ventriculotomy. Ventricular tachycardia (VT) was produced by occlusion followed by reperfusion of the left anterior descending coronary artery. During each VT, activation mapping was performed and early sites determined. Pace-map correlates (sites at which endocardial pacing produced a similar QRS morphology to that of the VT) were also determined. Isochronous maps were constructed for activation mapping and pace-mapping. There was a total of 29 morphologically distinct VTs. Groups were delineated according to correlations between activation mapping and pace-mapping. In 14 episodes of VT (group 1), pace-mapping confirmed the findings of activation mapping with all early sites being pace-map correlates (total number of early sites (tES) = 19; total number of pace-map correlates (tPMC) = 88; tES same as tPMC = 19). In 9 episodes of VT (group 2), there was a partial correlation between pace-mapping and activation mapping, such that pace-mapping when used with activation mapping appeared to further delineate the region of arrhythmogenesis (tES = 31; tPMC = 59; tES same as tPMC = 14). In 6 episodes of VT (group 3), there was no correlation between pace-mapping and activation mapping (tES = 15; tPMC = 0). With the balloon apparatus, endocardial activation mapping can be performed without the need for sustained monomorphic VT, and endocardial pace-maps may be generated easily.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Finger joint contact areas and pressures.

Although the joints of the index finger are similar geometrically and kinematically, the occurrence of degenerative joint disease is more frequent and severe in the distal interphalangeal joint. Much circumstantial evidence exists to suggest a mechanical cause for the observed differences in frequency. This article presents the results of in vitro experiments designed to determine contact areas and average pressures in the joints of the human index finger for positions simulating tip pinch and power grasp. The results show that the highest average contact pressures do, in fact, occur in the distal interphalangeal joint. Average joint contact pressure correlates well with clinically observed patterns of frequency of degeneration and degenerative joint disease score. This correlation between clinical experience and experimental results indicates that mechanical stress is among the factors responsible for the initiation and/or propagation of degenerative joint disease in the joints of the finger.

Biomechanical Phenomena↗
PubMed1985

Portoenterostomy diversion. Experimental study in antireflux technique.

Ascending cholangitis was induced in dogs by performing a biliodigestive Roux-Y anastomosis. Then two valvular antireflux mechanisms were performed on separate groups of these dogs with the aim of preventing the onset of ascending cholangitis. One was performed by a laterolateral plicature at the intestinal anastomosis and the other by invagination of the mucosa in the nonworking loop that had been anastomosed to the bile duct. All the dogs underwent analytic tests over a period of 3 months and histopathologic tests at the end of the study period. Results showed cholangitis and pericholangitis in the liver biopsy specimens of the group with no antireflux valve, to a lesser degree in the group with laterolateral plicature, and almost none in the animals with the invaginated valve.

Animals↗
PubMed1984

Fracture of long bones: rate effects under singular and combined loading states.

This study was undertaken to determine the effect of loading rate on bone failure under singular and combined loading states. Using the entire loading range of an Instron Materials Testing Machine, 190 pairs of canine radii were tested. One bone of each pair was subjected to either torsional or a combination of axial and torsional loads, and compared with a control specimen. Compressive loads of 4.6 and 11.5 N were utilized. Torque to failure and energy data versus loading rate were plotted. As loading rate increased, the torque and energy values were found to increase, reach a peak, and then decline at higher rates. Fractures produced under the combined state of loading are representative of those clinically found in human trauma situations.

Animals↗
PubMed1984

A technique for determining prosthetic joint contact areas.

A technique to determine the contact areas of total joint replacements has been developed. A thin film of petroleum jelly is deposited by the metallic component on the plastic component when load is applied. Fingerprint powder is then used to highlight the petroleum jelly coated area. Experimental data produced using this technique was found to be in good agreement with theoretical predictions.

Joint Prosthesis↗
PubMed1984

Pulmonary artery balloon counterpulsation for right ventricular failure: I. Experimental results.

The effects of pulmonary artery balloon counterpulsation (PABC) as a circulatory assist for the failing right ventricle were investigated. Sixteen anesthetized dogs underwent instrumentation to measure cardiac output and to record pressures in both ventricles, the pulmonary artery, and the aorta. Autonomic control of the heart was surgically and pharmacologically ablated. A specially designed counterpulsation balloon was inserted through the right ventricular (RV) outflow tract into the pulmonary artery. Pulmonary hypertension, induced acutely by the microembolization of the pulmonary circulation with glass beads combined with infusion of serotonin, served as a model for development of acute RV failure. Immediate effects of PABC were investigated in 10 dogs during normal function and failure of the right ventricle at different levels of preload. After further embolization which caused progressive cardiogenic shock, the effects of 10 minutes of PABC, and of its withdrawal, were examined. In all cases, PABC immediately decreased RV preload and afterload. In the failing right ventricle, counterpulsation also significantly increased cardiac output. Progressive cardiogenic shock was successfully reversed by PABC; after 10 minutes of counterpulsation, increases in cardiac output (+53%), arterial pressure (+55%), and RV minute work (+62%) were observed, paralleled by a fall in RV preload (-22%). After PABC was discontinued, the circulatory status again began to deteriorate. We conclude that PABC effectively improves function of the failing right ventricle caused by acute pulmonary hypertension.

Animals↗
PubMed1984

Pulmonary artery balloon counterpulsation for right ventricular failure: II. Clinical experience.

The use of pulmonary artery balloon counterpulsation (PABC) provided immediate salvage following cardiac surgical procedures in 2 patients with biventricular failure in whom inotropic drugs and intraaortic balloon counterpulsation did not provide sufficient support to allow weaning from cardiopulmonary bypass. Although both patients eventually died, the hemodynamic effectiveness of PABC was documented. The various clinical settings for right ventricular as well as biventricular failure are reviewed, the currently available options for treatment are summarized, and the directions for future laboratory investigation and possible clinical applications are presented.

Aged↗
PubMed1984

Operative therapy for ventricular arrhythmia.

The history of surgical attempts to control ventricular arrhythmia is reviewed and current methodology is presented in detail. The results of the various surgical approaches and future trends in the management of this troublesome condition are discussed.

Arrhythmias, Cardiac↗
PubMed1983

Changes in left ventricular performance related to perioperative myocardial infarction in coronary artery bypass graft surgery.

Strict electrocardiographic, enzymatic, scintigraphic, and hemodynamic criteria for perioperative myocardial infarction (MI) were defined and related to serial assessments of left ventricular performance during rest and exercise in patients seen early and late after coronary artery bypass graft operation. Global left ventricular performance was determined by radionuclide ventriculography from which changes in the pattern of serial postoperative ejection fractions (EF) were obtained. Patients were divided into two groups based on the presence or absence of perioperative MI, and were matched in pairs on the basis of preoperative EF and extent as well as location of coronary artery obstructions. The results indicate that neither short- nor long-term depression in resting EF occurred subsequent to perioperative MI. However, an exercise-related increase in EF eight months postoperatively was depressed in patients who had perioperative MI compared with those who did not. Patients with new Q waves and abnormal postoperative elevation in serum levels of the myocardial isoenzyme of creatine kinase (CK-MB) had a greater early decrease in EF compared with patients without evidence of perioperative MI. However, seven days after operation, the EF in both groups returned to preoperative levels. Patients with abnormal technetium 99m-pyrophosphate scintigrams had changes in perioperative EF similar to those in patients without MI. The presence of low cardiac output syndrome immediately after operation was associated with immediate and short-term decreases in EF, which were not seen in any of the other patient subgroups.

Cardiac Output, Low↗
PubMed1983

Operative therapy of malignant ventricular rhythm disturbances.

Pre- and postoperative electrophysiologic study (EPS), intraoperative cardiac mapping, and extended endocardial resection of scar (EER) has enabled us to identify subgroups among 94 patients who have had operation to control or prevent malignant ventricular arrhythmia. Operative mortality was 8.5% and cure or prevention of ventricular arrhythmia was accomplished in 92% of survivors. Group 1: 13 patients were resuscitated from "sudden death" due to ventricular fibrillation (VF). All had exercise-induced VF and/or ventricular tachycardia (VT). Preoperative EPS revealed no inducible VT/VF. All had coronary artery disease, without evidence of myocardial infarction (MI) or ventricular wall motion abnormality; all were cured with conventional myocardial revascularization. Group 2: 65 patients had MI with residual left ventricular wall motion abnormality, usually aneurysm. The malignant arrhythmia, either sustained VT (38 patients) or VF (27 patients), was inducible by EPS but not usually by exercise, and all were refractory to medical therapy. Treatment was operative mapping, aneurysmectomy, EER, and coronary revascularization. Operative mortality was 11.9%; 90% of survivors are arrhythmia free, off drugs; 10% are now drug responsive. Group 3: 3 patients without coronary disease had VT or VF caused by endocardial sarcoidosis or operative scar from a previous congenital heart operation. Treatment was EPS, operative mapping, and excision of abnormal endocardial scar with no operative mortality. Group 4: 13 patients underwent aneurysmectomy for indication other than arrhythmia, but had preoperative ventricular irritability which was not life-threatening. Operation was aneurysmectomy, prophylactic EER, and revascularization with no mortality and no postoperative arrhythmic events. After many years of unpredictable and unsatisfactory results from various empirical surgical approaches, the operative treatment of malignant ventricular arrhythmia is now based on sound electrophysiologic principles.

Arrhythmias, Cardiac↗
PubMed1983

Cardiac and renal responses to cross-clamping of the descending thoracic aorta.

The present study was performed to document the relative efficacy of commonly applied techniques used adjunctively during 1 hour of descending thoracic aortic cross-clamping. Renal and cardiac responses were determined by standard laboratory methods. There were four experimental groups: (1) heparin-bonded shunt; (2) partial femoral-femoral bypass; (3) sodium nitroprusside; (4) control. Each of the experimental groups showed abnormal hemodynamic responses during cross-clamping. Elevations in left ventricular end-diastolic pressure (LVEDP) and systolic blood pressure were common events during clamping, and cardiac output often decreased. Nevertheless, left ventricular performance curves after cross-clamping showed similar increases in left ventricular stroke work (LVSW) with increasing preload. In addition, left ventricular biopsy specimens showed preservation of myocardial high-energy phosphate stores and essentially normal ultrastructural integrity. Radioactive microspheres generally showed increased myocardial blood flow during and after cross-clamping, but no evidence of preferential subendocardial ischemia. Examination of renal function showed a marked decrease in urine output, glomerular filtration rate, and renal plasma flow during cross-clamping. Following the release of the cross-clamp, renal function returned to 50% to 85% of baseline status. Since we could find no major advantage of any of the techniques employed under the present experimental conditions, we suggest that all of the techniques should be part of the surgical armamentarium and the particular preoperative and/or intraoperative findings in a specific case should determine which technique is most appropriate for a given patient.

Adenosine Triphosphate↗