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Biomedical subjects

J F Moran

Publications and source records attributed to J F Moran.

At least 19 recordsLinked to original sources
PubMed1992

The clinical significance of exercise-induced bundle branch block.

Exercise-induced bundle branch block is an uncommon electrocardiographic entity said to be associated with coronary heart disease. Thirty-seven patients were studied to determine if exercise hemodynamics and stress/rest thallium scans could identify those patients with coronary heart disease. Eighteen patients of the study group also had coronary angiography. Group I (n = 17) with normal thallium scans and group II (n = 20) with abnormal thallium scans had significantly different maximal heart rate, maximal blood pressure, and double product in exercise as well as duration of exercise. Clinical evaluation of the patient study group permitted a division of the patients into two subgroups: group A, atypical chest pain or abnormal exercise electrocardiogram (n = 12), and group B, definite or probable angina (n = 25). Group B patients had significantly more abnormal thallium scans (17/25) than group A patients (3/12) (p less than 0.04). When compared to coronary angiography, stress/rest thallium scans had a predictive accuracy of 85% for coronary heart disease. While exercise-induced ST-segment depression and R wave amplitude increases are not specific in exercise-induced bundle branch block, exercise hemodynamics and stress/rest thallium scans can help diagnose patients with coronary heart disease. These test findings added to a clinical evaluation permit a more accurate stratification of the patients and indicate which patients need further study.

Bundle-Branch Block↗
PubMed1990

Electrophysiological testing and nonsustained ventricular tachycardia. Use and limitations in patients with coronary artery disease and impaired ventricular function.

Electrophysiological testing was performed in 100 consecutive patients with spontaneous asymptomatic nonsustained ventricular tachycardia, chronic coronary artery disease, and ejection fraction of less than 40%. Fifty-seven patients without inducible sustained ventricular arrhythmias were discharged on no antiarrhythmic therapy. Sustained monomorphic ventricular tachycardia was induced in 37 patients, and polymorphic ventricular tachycardia or ventricular fibrillation was induced in six patients. Of the 43 patients with inducible sustained ventricular arrhythmias, three had spontaneous cardiac arrest during serial drug testing and were excluded from further analysis. Twenty patients were discharged on drug therapy, resulting in suppression of inducible sustained ventricular arrhythmias. The remaining 20 patients with persistently inducible sustained arrhythmias were discharged on drug therapy, resulting in maximal rate slowing of the induced tachycardia. During a mean follow-up of 16.7 months, there were 10 recurrent cardiac arrests or sudden deaths. The 1- and 2-year actuarial incidence of these events was 2% and 6%, respectively, in patients without inducible sustained ventricular arrhythmias; 0% and 11%, respectively, in patients in whom inducible arrhythmias were suppressed; and 34% and 50%, respectively, in patients with persistently inducible sustained ventricular arrhythmias. Multivariate Cox analysis identified only the persistence of inducible sustained ventricular arrhythmias as a significant independent predictor of sudden death or recurrent sustained arrhythmias (p less than 0.001; relative risk, 3.5; 95% confidence intervals, 2.1-4.9). In this population, therapeutic intervention to prevent sudden death is unnecessary in patients without inducible sustained ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Electrocardiographic J waves after resuscitation from cardiac arrest.

A patient was monitored prior to, during, and after cardiac arrest with a Holter monitor and an electrocardiograph. The arrest occurred without any premonitory signs on the ECG. At the onset of the arrest, torsades de pointes ventricular tachycardia occurred, which quickly degenerated into ventricular fibrillation. After a successful second defibrillation, the patient developed Osborn waves, which subsided within a few minutes.

Coronary Artery Bypass↗
PubMed1989

Long term survival of class IV heart failure patients treated with oral amrinone.

The purpose of this study was to evaluate the effect of amrinone on the survival of a group of 51 Class IV congestive heart failure patients as well as changes in exercise capacity, hemodynamics, and clinical status. In those 22 patients able to exercise before treatment with amrinone, exercise duration increased from 4.15 minutes to 6.58 minutes on the treadmill. In those 19 patients first treated with intravenous amrinone, there was an increase in cardiac index from 1.9 to 2.6 L/min/m2. Thirty seven patients (72%) died in the follow-up period, most in the first four months. In this group of Class IV heart failure patients, there were two subsets of patients: one with a stable course (Group I) and one with a malignant course (Group II). The Group II patients accounted for much of the mortality in the follow-up. Patients with coronary artery disease did worse than patients with idiopathic dilated cardiomyopathies. There was no evidence that amrinone shortened or prolonged the survival of these Class IV patients.

Aged↗
PubMed1989

Alteration of red cell deformability during extracorporeal bypass: membrane v bubble oxygenator.

Red cell deformability is essential for normal microcirculation, since the red cell is greater in diameter than the caliber of small capillaries. Red cell filtration rate (RFR) was measured using a 5 microns nucleopore polycarbonate filter as an index of red cell deformability before, during, and after two hours of extracorporeal circulation for coronary artery bypass surgery, with a bubble oxygenator (eight patients) or a hollow fiber membrane oxygenator (14 patients). RFR decreased steadily and significantly during bypass in the bubble oxygenator group. After the start of bypass, RFR was significantly higher at all measurement intervals in the membrane oxygenator group as compared with the bubble oxygenator group. It can be postulated that significantly impaired red cell deformability caused by the bubble oxygenator is attributed to mechanical damage secondary to a huge blood-gas interface, and possibly to neutrophil-mediated oxygen free radical formation due to complement activation. Results indicate that the hollow fiber membrane oxygenator is superior to the bubble oxygenator in maintaining red cell deformability.

Carbon Dioxide↗
PubMed1989

Neonatal aortic thrombosis complicating umbilical artery catheterization: successful treatment with retroperitoneal aortic thrombectomy.

A newborn infant with a history of umbilical artery catheterization had renal vascular hypertension and congestive heart failure. An abdominal ultrasound examination revealed aortic thrombosis extending from the celiac axis to the aortic bifurcation. Retroperitoneal aortic thrombectomy was performed without difficulty. The infant's hypertension and cardiac failure resolved. The retroperitoneal approach allowed excellent exposure of the aorta and avoided the postoperative gastrointestinal morbidity associated with a transperitoneal approach.

Aorta, Abdominal↗
PubMed1988

Regulation by chronic drug administration of neuronal and cardiac calcium channel, beta-adrenoceptor and muscarinic receptor levels.

Chronic administration of atropine (40-100 mg/kg, 23 days) produced a 29-33% increase in muscarinic receptors, measured by [3H]quinuclidinyl benzilate binding, in rat brain. Diisopropyl phosphorofluoridate (0.9 mg/kg, 14 days) produced a 35% decrease in muscarinic receptors. Propranolol administration (800 micrograms/kg/hr, 10 days) increased beta-adrenoceptors, measured by [3H]dihydroalprenolol binding, by 69 and 50% in brain and heart respectively. Isoproterenol administration (800 micrograms/kg/hr, 10 days) produced a 50% reduction in cardiac beta-adrenoceptors but did not alter brain receptors. These drug treatments were without effect on binding of the Ca2+ channel ligands, [3H]nimodipine and [3H]nitrendipine, to brain or heart respectively. However, chronic administration of nifedipine for 20 days (36 and 360 micrograms/kg/hr) did produce down-regulation of both cardiac and neuronal Ca2+ channels and a similar down-regulation of beta-adrenoceptors. Co-regulation of Ca2+ channels and neurotransmitter receptors may occur but may not be an automatic consequence of either receptor or channel regulation.

Animals↗
PubMed1988

Effect of thyroid status on beta-adrenoceptors and calcium channels in rat cardiac and vascular tissue.

To determine the influence of thyroid hormone on beta-adrenoceptors and Ca2+ channels, rats were treated with thyroxine (75 micrograms/100 g sc daily for 5 days) or propylthiouracil (0.05% in drinking water for 30 days). beta-Adrenoceptor density in ventricular tissue, measured by [125I]iodocyanopindolol binding, was significantly increased and decreased respectively, following thyroxine or propylthiouracil treatment to 124.7 +/- 7.11 fmol/mg protein and 71.98 +/- 5.37 fmol/mg protein from euthyroid (control) levels of 93.7 +/- 4.58 fmol/mg protein. Ca2+ channel density, measured by [3H]nitrendipine binding, was altered in the opposite direction; it was significantly decreased and increased to 324 +/- 24 fmol/mg protein and 691 +/- 31 fmol/mg protein from 562 +/- 35 fmol/mg protein after thyroxine or propylthiouracil treatment, respectively. No changes in affinity of either ligand were observed. Responses of isolated papillary muscles from propylthiouracil-treated animals accorded with changes seen in the binding studies. The geometric mean EC50 of isoproterenol increased from 9.5 x 10(-9) mol/l to 5.5 x 10(-8) mol/l, and the EC50 for calcium decreased from 3.16 x 10(-3) mol/l to 1.36 x 10(-3) mol/l; moreover, the responsiveness to the Ca2+ channel activator Bay K 8644 was increased. The corresponding responses in thyroxine-treated animals could not be examined because of prominent arrhythmic activity. As with papillary muscles the sensitivity of left atria to isoproterenol was decreased after treatment with propylthiouracil, with geometric mean EC50 values increasing from 3.21 x 10(-9) mol/l to 89.4 x 10(-9) mol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Surgical management of pleural space infections.

Adequate drainage of pleural space infections is generally required to achieve resolution of the infection and full expansion of the underlying lung. An understanding of the normal pathologic evolution of pleural infection is necessary to choose the optimal method of pleural drainage. The timing of surgical drainage and the choice of drainage procedure in each case should be based upon the duration of the infection, the characteristics of the pleural fluid, the presence of loculations within the pleural space, and the overall condition of the patient. Thoracentesis should be performed to confirm a suspected diagnosis of pleural empyema. The diagnostic information from thoracentesis may be augmented by imaging techniques such as computed tomography, ultrasound, or empyemagrams. Such radiographic studies are important in the planning of either closed or open drainage. Repeated thoracentesis are rarely adequate for drainage of an established empyema. Closed tube thoracostomy requires careful placement and is very effective if instituted in the early stage of pleural infection. Open drainage with rib resection for chest tube placement is probably the most versatile form of pleural drainage. Decortication is promptly curative and should be employed in the latter stages of empyema in patients who can tolerate the procedure. Chronic open flap drainage is reserved for debilitated patients or patients with destroyed underlying lung.

Bacterial Infections↗
PubMed1986

The response of patients with complex ventricular arrhythmias secondary to dilated cardiomyopathy to programmed electrical stimulation.

A prospective study was undertaken to assess the response of patients with idiopathic dilated cardiomyopathy to programmed electrical stimulation (PES). Fifteen patients undergoing evaluation of congestive heart failure were studied. All patients underwent cardiac catheterization and coronary angiography as well as endomyocardial biopsy to exclude known causes of heart failure. No patient had a history of syncope or sustained ventricular arrhythmias. All patients were found to have severe left ventricular dysfunction (mean ejection fraction 17%), as well as nonsustained ventricular tachycardia on ambulatory monitoring or exercise testing. A protocol using up to two premature stimuli and burst pacing, from two right ventricular sites, induced up to four repetitive ventricular responses but failed to induce a sustained ventricular arrhythmia in any patient. Patients with dilated cardiomyopathy, advanced ventricular arrhythmias, and depressed left ventricular function respond differently than do patients with coronary artery disease, advanced ventricular arrhythmias, and depressed left ventricular function, to PES. PES appears to have limited value in the evaluation of patients with dilated cardiomyopathy and nonsustained ventricular arrhythmias.

Adult↗
PubMed1986

Augmentation of cardiac output by external cardiac pacing: pacemaker-induced CPR.

Transthoracic cardiac pacing is frequently associated with simultaneous stimulation of skeletal muscle and nerves. We describe a patient in cardiogenic shock and complete heart block in whom the associated vigorous abdominal and chest muscle contractions caused by transthoracic cardiac pacing resulted in a marked augmentation of cardiac output and systemic blood pressure via a "CPR" effect.

Aged↗
PubMed1986

Twelve years of clinical experience with lithium pulse generators.

The clinical performance of 9,651 lithium pulse generators, which were implanted at our registry hospitals since 1973, was assessed by analysis of actuarial survival data and information obtained at the time of pacemaker failure. Cumulative survival estimates for all units were: 5 years, 94 percent, 7 years, 81 percent, 10 years, 62 percent. Discriminant actuarial analysis revealed no differences between lithium iodine and lithium cupric sulfide longevity. Battery depletion was found in 49.1 percent of 277 units subjected to detailed explant analysis, while 31 percent and 8.7 percent had component and hermetic seal defects, respectively. Of the pulse generators with battery depletion, all but two units exhibited normal end-of-battery life behavior. We conclude that the lithium iodine and lithium cupric sulfide batteries are safe, long-term energy sources; however, the impact of reduced battery size and dual chamber pacing on these performance parameters is unknown.

Electronics, Medical↗
PubMed1986

Pacemaker malfunction: fact or artifact?

In summary, the present examples illustrate how pacemaker malfunction can be simulated by the sources of artifact produced or detected by the monitoring equipment. This form of pseudopacemaker malfunction remains a common cause of mistaken diagnosis of pacemaker malfunction. A thorough understanding of the examples outlined above should help distinguish true pacemaker malfunction from pseudopacemaker malfunction produced by artifact.

Amplifiers, Electronic↗
PubMed1985

Dilated cardiomyopathy: functional status, hemodynamics, arrhythmias, and prognosis.

The natural history of dilated cardiomyopathy is variable, and the prognosis difficult to predict. Several clinical and hemodynamic parameters have been proposed as prognostic indicators. Reports on the relationship between ventricular arrhythmias, degree of hemodynamic impairment, and sudden death are controversial. To define accurately the prognosis in dilated cardiomyopathy, 55 patients with this clinical syndrome underwent clinical evaluation, radionuclide ventriculography, echocardiography, 12-lead electrocardiography, and 24 hr ambulatory monitoring, and the data thus obtained were evaluated based on predictive value. Over a follow-up period of 14.1 +/- 7.9 months, 11 patients (20%) died, all suddenly. Univariate analysis revealed that patients with more severe functional impairment (P = 0.0449), lower cardiac index (P = 0.0226), lower ejection fraction (P = 0.0426), and higher pulmonary artery wedge pressure (P = 0.0314) had greater mortality risk. Age, duration of symptoms, 12-lead electrocardiographic abnormalities, and atrial arrhythmias were not predictive of higher mortality. The number of PVCs per hr, the occurrence of couplets, the degree of PVCs prematurity, and the presence, frequency, rate, and duration of ventricular tachycardia did not have prognostic significance. A stepwise discriminant analysis identified functional class, cardiac index, and presence or absence of multiform PVCs as the group of variables that together could more accurately predict outcome in our dilated cardiomyopathy patients. Using a formula derived from the results of this analysis, the outcomes of 36 of 49 patients (74%) was correctly predicted, with a specificity of 100% and a sensitivity of 70%.

Adult↗
PubMed1985

Pacemaker malfunction simulated by amplifier saturation.

In this case report, pacemaker malfunction is simulated by prolonged pauses after each pacemaker discharge. The pauses were due to saturation of the input of the telemetry monitor amplifier by the discharge voltage of the pacemaker. It is important to recognize amplifier saturation as a form of artifact that can mimic pacemaker malfunction.

Aged↗
PubMed1985

Pleural and chest wall invasion in bronchogenic carcinoma: CT evaluation.

CT scans of 47 patients who had peripheral bronchogenic carcinoma contiguous to the pleural surface and who had undergone thoracotomy were retrospectively reviewed. The CT features of the primary neoplasm that were analyzed included the angle and amount of contact with the adjacent pleural surface, associated pleural thickening, fat plane between the tumor and chest wall, rib destruction, and chest wall mass. CT was of limited predictive value in separating those patients who had parietal pleural/chest wall involvement from those who did not. The combination of two or three CT findings (obtuse angle, greater than 3 cm contact with pleural surface, associated pleural thickening) resulted in a sensitivity of 87% and a specificity of 59%. The clinical symptom of focal chest pain, while not as sensitive (67%) as CT, was much more specific (94%) for parietal pleura/chest wall invasion.

Adenocarcinoma↗
PubMed1984

Exercise induced "Mobitz type II" second degree AV block in a patient with chronic bifascicular block (right bundle branch block and left anterior hemiblock).

A 55 year old healthy man with chronic bifascicular block (right bundle branch block and left anterior hemiblock) had a near syncopal episode. A treadmill test showed exercise induced Mobitz type II AV block manifested clinically by paradoxical slowing of the heart rate and decreased blood pressure. True His Purkinje block and pseudo AV block due to His extrasystoles were documented by an electrophysiological study.

Blood Pressure↗