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Biomedical subjects

J M Moran

Publications and source records attributed to J M Moran.

At least 73 records · Page 4Linked to original sources
PubMed1982

Clinical evaluation of the relative effectiveness of multidose crystalloid and cold blood potassium cardioplegia in coronary artery bypass graft surgery: a nonrandomized matched-pair analysis.

Controversy exists concerning the most effective method of myocardial protection during coronary artery bypass graft operations. Accordingly, we performed a matched-pair analysis between 25 patients receiving multidose hypothermic potassium crystalloid cardioplegia and 25 other patients receiving cold blood potassium cardioplegia. Patients were matched on the basis of preoperative ejection fraction (EF) and the number of anatomically similar stenotic coronary arteries. The adequacy of myocardial protection was assessed by serial perioperative determinations of radionuclide ventriculography, hemodynamic measurements, analyses of electrocardiograms and serum levels of MB-CK. We found that the level of myocardial protection was similar between unstratified groups. However, when subgroups were selected on the basis of prolonged aortic cross-clamp time (greater than ninety minutes) or impaired preoperative left ventricular function (EF less than 40%), there was a suggestion that cold blood cardioplegia may be advantageous.

Adult↗
PubMed1982

Extended endocardial resection for the treatment of ventricular tachycardia and ventricular fibrillation.

A total of 40 patients with drug-refractory, life-threatening cardiac rhythm disturbances--ventricular tachycardia in 23 patients and ventricular fibrillation in 17 patients--underwent extended endocardial resection (EER) of scar tissue. Scarring was due to myocardial infarction in 38 patients, to previous congenital heart operation in 1 patient, and to sarcoidosis of the heart in 1. The EER procedure was directed by epicardial and endocardial mapping data whenever possible, and was usually combined with revascularization, aneurysmectomy, or, in 5 patients, mitral valve replacement. Operative mortality was 10%, incident to poor preoperative ventricular function and hemorrhage secondary to previous cardiac surgical procedures. Thirty-three of the 36 survivors (92%) are free of arrhythmia at follow-up periods ranging from 3 to 36 months (mean, 12.5 months); the arrhythmia in the remaining 3 patients is now drug controlled. Thirty-three patients had postoperative electrophysiological studies, and in 30 (91%), the arrhythmia was no longer inducible. The results of surgical treatment for ventricular tachycardia and ventricular fibrillation were similar. The results also proved satisfactory whether the EER procedure was directed by visual observation or mapping.

Adolescent↗
PubMed1981

Autonomic interactions among subsidiary atrial foci.

Although the existence of a specific pacemaker hierarchy outside of the sinus node but within the atrium has been documented, little evidence regarding mechanisms controlling activity of these sites has been gathered. This investigation utilized an autologous perfusion of the sinus nodal artery, by way of the femoral artery, in order to suppress the sinus node cholinergically while unmasking latent atrial sites. Electrograms were recorded from the region of the sinus node and several atrial sites. Perfusion with small doses of acetylcholine and physostigmine unmasked pacemakers outside of the sinus and atrioventricular nodes, but within the atrium. Either vagal stimulation or topical acetylcholine on the area of the presumed pacemaker returned dominance gradually toward the sinus node. Stimulation of the right stellate ganglion accelerated the latent pacemaker but did not shift activation toward the sinus node. These results are consistent with the existence of subsidiary atrial pacemakers that appear to be highly sensitive to the effects of acetylcholine. This may represent one mechanism, in addition to overdrive suppression, that maintains pacemaker hierarchy within the right atrium.

Acetylcholine↗
PubMed1981

Nonrandomized matched pair analysis of intermittent ischemic arrest versus potassium crystalloid cardioplegia during myocardial revascularization.

The quest for the ideal method of myocardial preservation during coronary artery bypass graft (CABG) surgery continues at a rapid pace. Nevertheless, in the present clinical practice of cardiac surgery, the choice is chiefly between hypothermic intermittent ischemic arrest and hypothermic potassium cardioplegia. This study applies newer technics in radionuclear cardiology, as well as more conventional enzymatic, electrocardiographic, and hemodynamic determinations, to the evaluation of the effectiveness of the previously mentioned modes of myocardial protection. Serial assessments are made preoperatively as well as during the first ten days postoperatively. We find that the perioperative incidence of myocardial damage and changes in left ventricular performance are almost identical using either method in patients with relatively normal preoperative left ventricular performance who do not have severe preoperative refractory ischemia or necrosis.

Aged↗
PubMed1981

Accuracy in coronary graft flow measurement.

A blood flow calibration apparatus is described for use with electromagnetic flow probes. It is an automatic gravity-flow system, which provides a constant level and therefore constant flow at any preset rate. On several occasions, the use of this device has helped to determine whether flow probes require simple adjustment, factory repair, or replacement. Using this system, a systematic error in the manufacturer's "precalibration" averaging +22% (range, 9 to 50%) has been discovered, and appropriate corrections have been made. The accuracy of these corrections has been confirmed by a rapid, in vivo method of calibration, which also is described and which can be carried out during the conduct of aortocoronary bypass operation. It is recommended that all groups measuring coronary graft flow become familiar with their electromagnetic flowmeter and probes by means such as those described, in the interest of accurate flow measurement after bypass operation.

Blood Flow Velocity↗
PubMed1981

Sensitivity differences of SA and AV node to vagal stimulation: attenuation of vagal effects at SA node.

The present study sought to characterize vagally induced desensitization at the sinoatrial (SA) node of the intact dog and to determine whether these findings could be extended to atrioventricular (AV) Nodal conduction. Autonomically decentralized anesthetized dogs were instrumented to record electrocardiograms, arterial pressure, and electrograms from the SA node, right atrium, right ventricle, and His bundle. During right- or left-vagal stimulation for 60 s, cycle length (CL) increased initially, followed by a gradual recovery toward control during stimulation; atrio-His (AH) interval remained prolonged throughout the stimulation. Atrial drive increased AH interval during stimulation, but AH prolongation was maintained throughout the stimulation period. To rule out acetylcholine (ACh) depletion, ACh was administered before and during vagal stimulation. Although control CL and AH interval were lengthened by ACh, no significant CL increases occurred when ACh was given during stimulation, but the AH interval became longer. Propranolol increased control CL and AH interval but did not alter the relationship between vagal stimulation and CL or AH interval. Thus the negative chronotropic effect of ACh at the SA node is diminished upon prolonged vagal stimulation, whereas the negative dromotropic effect upon AV nodal conduction remains unaltered. These results suggest differences in muscarinic receptor behavior at the SA and AV nodes.

Acetylcholine↗
PubMed1981

Serial assessment of left ventricular performance following coronary artery bypass grafting. Early postoperative results with myocardial protection afforded by multidose hypothermic potassium crystalloid cardioplegia.

Forty patients who recently underwent coronary artery bypass graft (CABG) operations had serial hemodynamic and scintigraphic studies. Multidose hypothermic potassium crystalloid cardioplegia was used for myocardial protection and newer techniques in anesthetic management and perioperative patient care were also employed. The method of equilibrium cardiac gated blood pool (GBP) scintigraphy was used to obtain perioperative changes in global ejection fraction (EF) and regional wall motion (RWM). Ninety percent of patients displayed a decrease in EF 2 hours postoperatively when compared to their preoperative values. This change was also associated with a fall in cardiac index (CI) and left ventricular stroke work index (LVSWI). Twenty-four hours postoperatively, EF and CI recovered to preoperative levels, but LVSWI remained depressed. Seven days postoperatively, global EF had improved to a value greater than the preoperative one (50% +/- 3% versus 57% +/- 4%, p < 0.05). Perioperative changes in RWM followed the same pattern as EF, but recovery in this index of regional contractility was faster than EF, since maximal improvement was observed 24 hours postoperatively. Thus transient left ventricular dysfunction is common immediately after CABG, but recent advances in myocardial protection and perioperative management are associated with short-term increases in regional and global left ventricular function documented by noninvasive GBP imaging.

Aged↗
PubMed1981

Simultaneous revascularization of coronary and vertebral arteries.

Simultaneous vertebral artery and coronary artery bypass are reported in a patient with unstable angina who exhibited signs and symptoms of vertebrobasilar insufficiency while awaiting myocardial revascularization. The indications and various technical options for vertebral artery bypass are reviewed, and the techniques applied in this case are described. Observations on coronary and vertebral vein graft flow, with and without intra-aortic balloon counterpulsation, are presented. Late patency of the aortovertebral vein graft has been documented, and the patient has been free from symptoms of vertebrobasilar and coronary insufficiency for 5 years.

Angina Pectoris↗
PubMed1980

Early and long-term improvement in left ventricular performance following coronary bypass surgery.

Changes in left ventricular performance after coronary artery bypass grafting (CABG) have been variable. Earlier studies based on contrast left ventriculography have shown occasional improvement in left ventricular function in patients with unstable angina or abnormal preoperative ventricular performance, but for the most part repeat cardiac catheterization several months after operation has shown no significant changes in global left ventricular contraction. In the past few years, advances in radiopharmaceutical technology have made the characterization of left ventricular wall motion accurate and highly reproducible. Since prognosis in patients with coronary artery disease and survival after CABG have been related to global ejection fraction (EF), we employed prospectively on analysis of short-term and long-term changes in EF after CABG utilizing multidose hypothermic potassium crystalloid cardioplegia as the method of myocardial protection. Concomitantly, newer techniques in anesthesia and perioperative patient management were employed to minimize myocardial damage in these patients. Postoperative scintigraphic evaluation showed a transient (2-hour) depression in left ventricular function, followed by recovery to preoperative levels at 24 hours and significant improvement in EF at 7 days. From 7 days to 8 months postoperatively, there was no further change in resting EF, but there was another significant exercise-induced increase in EF at the long-term examination. Thus, present advances in the multidisciplinary management of patients with coronary artery disease are associated with improvement in resting and exercise-related EF postoperatively.

Aged↗
PubMed1979

Synthetic peptides comprising sequences of the human immunoglobulin E heavy chain capable of releasing histamine.

On the basis of previous studies on the structure-activity relationship of model polypeptide histamine liberators, a site within the Fc region of immunoglobulin E antibody molecules has been proposed as that responsible for the direct triggering of target mast cells after antigen challenge. Peptides comprising this region of the epsilon-chain have now been synthesized and shown to induce histamine release from normal rat peritoneal mast cells in a selective manner essentially similar to that mediated by anaphylactic antibody-antigen interaction.

Animals↗
PubMed1979

Thoracic aortic imaging without angiography.

Imaging of the thoracic aorta without recourse to angiography has great theoretic appeal. We have used computerized tomography (CT) in the initial evaluation of 297 patients with suspected mediastinal disease. Nineteen of this group had important findings related to the thoracic aorta: aortic dissection (six), descending thoracic aortic aneurysm (nine), suspected aortic trauma (three), and suspected false aneurysm at a coarctation repair (one). In all cases, the aorta and related pathology were readily demonstrated by CT, aided by the intravenous infusion of contrast material. In 13 of 15 cases, aortic dissection and aortic aneurysm could be accurately diagnosed. In two instances of ascending aortic dissection, it was not possible to distinguish the false lumen from mural thrombus in an atherosclerotic aneurysm.

Aorta, Thoracic↗
PubMed1979

The advantages of open mitral commissurotomy for mitral stenosis.

Mitral commissurotomy is the treatment of choice for mitral stenosis. If this is not feasible, replacement of the valve becomes necessary. Open commissurotomy has been performed at Loyola University Medical Center, Maywood, Ill, in 105 patients since 1970. The mean age was 45 years. The indication for surgery was heart failure in 92 of the cases. Sixty of the patients were in class 3 of the New York Heart Association (NYHA) classification. Eighty-five underwent open mitral commissurotomy alone. This was not feasible in 42 patients scheduled for it who required valvular replacement. Twenty-five patients had a left atrial thrombus. Two patients died, one from aortic dissection and the other from acute infarction in the perioperative period. Ninety-eight patients are NYHA class 1 or 2 at present. Two patients required valvular replacement following the commissurotomy. The low mobidity and mortality with excellent long-term results support our contention that open mitral commissurotomy is the treatment of choice for mitral stenosis.

Adult↗