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Biomedical subjects

J M Roland

Publications and source records attributed to J M Roland.

51 records · Page 3Linked to original sources
PubMed1980

Management of aortic arch interruption with prostaglandin E1 infusion and microporous expanded polytetrafluoroethylene grafts.

Prostaglandin E1 infusion and a microporous expanded polytetrafluoroethylene graft were used in the management of eight infants, all less than 4 days old, with interruption of the aortic arch. Five of the six infants receiving prostaglandin E1 responded dramatically to this therapy, with return of lower limb pulses and lessening of metabolic acidosis. There were no adverse effects attributable to the prostaglandin E1 infusion. Seven infants subsequently underwent aortic reconstruction with a polytetrafluoroethylene graft. There were no operative deaths, and in up to 3 years of follow-up of these patients, graft obstruction occurred in only one patient and this graft was successfully revised. The long-term mortality rate was high (62 percent); all deaths but one were attributable either to the palliation or to the total correction of the associated cardiac malformations.

Aorta, Thoracic↗
PubMed1980

Randomised placebo-controlled trial comparing oxprenolol with disopyramide phosphate in immediate treatment of suspected myocardial infarction.

473 patients with suspected acute myocardial infarction were entered into a randomised, double-blind, placebo-controlled comparison of disopyramide phosphate, 150 mg three times a day, and oxprenolol, 40 mg three times a day. When analysed on an intension-to-treat basis there was no significant difference in 6-week mortality between the groups, but patients who were able to continue on the active medications fared better than the patients who had to be withdrawn. The withdrawal rate because of heart failure in patients randomised to receive disopyramide was significantly increased. Patients receiving this agent also showed a reduced number of arrhythmic episodes on 24-h tape recordings but this trend did not achieve statistical significance. The results show that the early use of either oxprenolol or disopyramide phosphate in patients with suspected acute myocardial infarction is unlikely to improve mortality.

Acute Disease↗
PubMed1980

Randomised trial comparing propranolol with atenolol in immediate treatment of suspected myocardial infarction.

The value of beta-blockade for suspected acute myocardial infarction was assessed by determining the six-week and one-year mortality rates in patients started on propranolol, atenolol, or placebo immediately on entry to a coronary care unit. A total of 388 patients entered this double-blind, randomised study, and when analysed on the basis of the initial, intention-to-treat categories there was no significant difference between the three groups in respect of the mortality rate at one year. There was, however, a high withdrawal rate from the trial; the reasons for this illustrate problems of physician compliance and interpretation of data, which are common to all early-entry trials of haemodynamically active agents in acute myocardial infarction.

Adult↗
PubMed1980

Transcatheter embolization in the management of congenital arteriovenous malformations.

Congenital arteriovenous malformations (AVMs) with multiple arterial feeders in eight patients were managed by transcatheter embolization with a combination of polyvinyl alcohol foam (Ivalon), detachable silicone balloons, and wool coils. Due to the extensive number of arterial feeders often present, multiple procedures with several days in between were frequently necessary. When possible, surgical resection after embolization is the procedure of choice. Inoperable AVMs are best managed by segmental distal embolization of all arterial feeders with a permanent occluding material. Embolization therapy as a primary form of management is considered palliative and temporary relief of symptoms is usually achieved.

Adolescent↗
PubMed1979

Effect of beta-blockers on arrhythmias during six weeks after suspected myocardial infarction.

Twenty-four-hour electrocardiographic tape-recording was used to investigate the incidence of arrhythmias in patients with suspected myocardial infarction who were receiving either propranolol, atenolol, or placebo. Recordings begun within 24 hours after admission to a coronary care unit showed that 76% of patients eventually found to have had a myocardial infarction had ventricular arrhythmias of a type generally regarded as serious, whereas of patients in whom myocardial infarction was not substantiated, only 24% had such arrhythmias. At one and six weeks after admission the incidence of arrhythmias ranged from 25% to 33% irrespective of diagnosis. Of patients monitored at both one and six weeks, however, only 5% had arrhythmias on each occasion. Patients treated with propranolol and atenolol showed a similar incidence of arrhythmias to those taking placebo. There was no difference in the incidence or type of arrhythmias recorded between patients who died and those who were still alive at six weeks.These results confirm that "serious" ventricular arrythmias occur in most patients during the acute phase of myocardial infarction and suggest that they do not constitute an independent risk factor. Beta-blockers showed little evidence of useful antiarrhythmic action in the dosage used, but increasing the dosage in suspected myocardial infarction is not practicable because of the risk of hypotension. The findings raise grave doubts about the value of studying arrhythmias to assess drugs intended to reduce mortality from myocardial infarction.

Arrhythmias, Cardiac↗
PubMed1979

Noninvasive evaluation of ventricular function in cystic fibrosis.

The cardiac function of 21 patients with cystic fibrosis was studied using radionuclides and M-mode echocardiography. The patients (mean age 13.2 years, range 4 to 27) had a wide range of clinical and pulmonary function abnormalities (mean Shwachman-Kulczycki score 62.1). Decreased right ventricular ejection fraction was found in 13 of 18 patients (72%); an additional four patients had abnormal septal motion on ECHO. Left ventricular ejection fraction was abnormal at rest in four patients (19%); an additional four patients had borderline low LVEF. The LV pre-ejection period to ejection time ratio increased significantly (i.e., worsening LV performance) with deterioration of S-K score, chest radiograph score, and forced expiratory volume in 1 second. Three of eight patients with normal LVEF at rest had an abnormal response to supine bicycle exercise: LVEF fell in two patients and was unchanged in one. Thus evidence of LV dysfunction was observed in seven of 21 (33%) of the patients; four at rest and in three only during exercise.

Adolescent↗
PubMed1979

Experimental evaluation of 2F transthoracic thermodilution cardiac outputs in small animals.

Cardiac output can be measured with a computer using a 2F transthoracic catheter placed during surgery. When injections are made into a central venous catheter, this technique allows for cardiac output measurements to be made in children with complex congenital heart disease not appropriate for placement of a transvenous pulmonary artery catheter. Using rabbits similar in size to the infants most likely to need this technique, 26 experimental comparisons of thermodilution and indocyanine green dye cardiac outputs were made with cardiac outputs as low as 0.2-0.4 liter/min. The relationship between green dye and thermodilution was statistically significant (p less than 0.001) and almost linear (r = 0.92). This documents the validity of both the 2F transthoracic catheter technique in the low range of cardiac outputs appropriate for infants and children.

Animals↗
PubMed1977

Time course of ventricular fibrillation threshold in infarcted and non-infacted myocardium after acute coronary ligation.

The time course of the ventricular fibrillation threshold (VFT) was studied in 10 open-chest mongrel dogs following acute occlusion of the left anterior descanding coronary artery (LAD). The VFT in the infarcted area was compared to a non-infarcted area of the left ventricle supplied by the circumflex coronary artery. Prior to coronary occlusion the mean VFT for the entire group of 10 animals was 14 ma. for the area supplied by the LAD and 17.6 ma. for the area of the left circumflex. Immediately after coronary ligation the VFT decreased in both areas. Within 90 to 120 minutes the VFT in the infarcted area was 27 ma. and after 6 hours of occlusion the VFT was 3 times the pre-ligation value. The VFT in the non-infarcted area remained near the pre-ligation values. The excitability of the infarcted area was markedly decreased after coronary occlusion and this accounted for the increase in the VFT in the infarcted area. In the non-ischemic area the excitability was unchanged during the entire six hour period following occlusion. The study stresses the importance of the location of the electrodes used for fibrillation and the natural course of the VFT in evaluating VFT's within the ischemic myocardium.

Animals↗
PubMed1977

Recognition of residual postoperative shunts by contrast echocardiographic techniques.

A bedside echocardiographic technique was used to detect and localize residual intracardiac shunts in 26 patients who had surgical repair of septal defects. Contrast echocardiography was performed through central venous and left atrial monitoring catheters at the same time as cardiogreen dye curves. Indicator dilution confirmed residual atrial defects in ten patients and ventricular defects in five. Contrast echocardiography indicated the presence and level of shunting in all 15 patients. Temporary flow through newly implanted septal patches was detected and differentiated from shunting across a true residual defect. The contrast echocardiographic technique using injections through the central venous and left atrial catheters as described detects and localizes right-to-left and left-to-right shunting. It is a safe and reliable method to evaluate residual intracardiac defects postoperatively.

Adolescent↗
PubMed1976

Effect of nitroglycerin on ventricular fibrillation threshold of nonischemic myocardium.

The threshold for ventricular fibrillation induced by a 200 msec train of pulses was measured during a control period and during an intravenous infusion of nitroglycerin in 14 nonischemic open chest dogs. Infusion of nitroglycerin in doses sufficient to reduce mean arterial blood pressure an average of 17 mm Hg was associated with a rise in ventricular fibrillation threshold from a control value of 24 +/- 3 (mean +/- 1 standard error of the mean) to 41 +/- 6 milliamperes (P less than 0.001). In a subgroup of six animals simultaneous infusions of nitroglycerin and phenylephrine abolished the hypotensive effect of nitroglycerin but did not significantly alter the rise in ventricular fibrillation threshold observed with nitroglycerin infusion alone. In five other animals mean arterial blood pressure was similarly reduced an average of 17 mm Hg by venous hemorrhage, but was associated with a lowering than a rise in ventricular fibrillation threshold from a prehemorrhage value of 28 +/- 6 to 15 +/- 2 milliamperes, (P less than 0.005). Thus, intravenously administered nitroglycerin raises ventricular fibrillation threshold in nonischemic canine myocardium independent of its hypotensive effects.

Action Potentials↗
PubMed1976

Echocardiographic detection of intracardiac right-to-left shunts following peripheral vein injections.

A contrast echocardiographic technique using peripheral vein injections for the detection and localization of intracardiac right-to-left shunting is described. Fifty children underwent cardiac catheterization and peripheral contrast echocardiographic studies. The site, degree, and direction of shunting were established at catheterization by oximetry, indicator dilution analysis and/or angiography. Peripheral vein injections were performed from the right antecubital vein or the right saphenous vein. Right-to-left shunts were documented at catheterization in 27/50 patients; contrast echocardiographic studies indicated the presence and level of shunting in all 27 patients. The contrast echocardiographic technique using peripheral vein injections detects and localizes right-to-left intracardiac shunting. It is a safe and sensitive method to evaluate systemic desaturation in ambulatory and postoperative patients.

Adolescent↗
PubMedDate not supplied

A rare form of isolated interrupted aortic arch: the value of two-dimensional echocardiography in the precatheterization evaluation.

Preoperative evaluation of a 12-year-old girl, previously diagnosed as having a coarctation of the aorta, revealed a rare form of isolated interruption of the aortic arch. Two-dimensional echocardiography played an important role in the delineation of the defect and significantly reduced the need for invasive techniques. It helped to anticipate problems in reaching left-sided structures at cardiac catheterization, saving time and unnecessary trauma. This technique also ruled out associated intracardiac anomalies that were not detailed at cardiac catheterization.

Aorta, Thoracic↗