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Biomedical subjects

A R Dobell

Publications and source records attributed to A R Dobell.

At least 37 records · Page 2Linked to original sources
PubMed1986

Atrial thrombi after the Fontan operation.

This report documents four instances of right atrial thrombi discovered from four days to five years after Fontan-type operations. Two of the thrombi were removed at reoperation, and two diminished in size during anticoagulation therapy. There were no pulmonary emboli in this small series, but the ominous implications of right atrial thrombi in the post-Fontan situation are obvious. For this reason we recommend regular echocardiographic surveillance of all patients who have had the Fontan operation and anticoagulation in certain situations.

Echocardiography↗
PubMed1986

Surgical treatment of pulmonary atresia with intact ventricular septum.

A concept of management of pulmonary atresia in infancy has been presented. The basic theme employed is that pulmonary valvotomy or an outflow patch should be applied to most infants so that a biventricular heart is achieved in as many children as possible. Clearly, a functioning right ventricle cannot result in all instances and systemic to pulmonary shunts have an important adjunctive and sometimes primary therapeutic role. Our ability to judge right ventricular capability has been improved by preoperative assessment of segmental cavitary hypoplasia by noninvasive echocardiography and angiographic techniques.

Ductus Arteriosus, Patent↗
PubMed1985

Improvement in resting ventricular performance following coronary bypass surgery.

To assess the changes in resting left ventricular (LV) function following coronary bypass surgery, technetium 99m-labeled multiple equilibrated blood pool gated scans were performed in 53 consecutive patients at rest, before operation, and at 24 hours and 1 week after operation. Left ventricular ejection fraction (LVEF) and end-diastolic volume (EDV) were measured. The LVEF increased significantly from a preoperative value of 49 +/- 2% to 56 +/- 2% at 24 hours after operation (p less than 0.05) and 56 +/- 2% at 1 week following operation (p less than 0.05 compared with the preoperative value). The EDV also exhibited significant changes, decreasing from a preoperative value of 148 +/- 8 ml to 91 +/- 11 ml at 24 hours (p less than 0.001) and 114 +/- 9 ml at 1 week (p less than 0.01 compared with the preoperative value). When the patients were divided into two groups according to the preoperative LVEF (Group 1, LVEF of greater than or equal to 50%; Group 2, LVEF of less than 50%), the observed changes were similar. This study demonstrates significant improvement in resting LV function 24 hours following coronary bypass surgery. This improvement persists at 1 week and is not related to the degree of preoperative impairment. We conclude that the combination of successful revascularization and optimal myocardial protection can result in significant improvement of LV function at rest.

Adult↗
PubMed1985

Distribution of lung vascular resistance after chronic systemic-to-pulmonary shunts.

Congenital cardiac shunts produce pathological lesions on the arterial side of the lung vasculature. We examined the effects of chronic shunts (14.2 +/- 1.2 mo) in 10 young dogs, between the left subclavian and the left lower lobe (LLL) artery, on pulmonary vascular pressure and flow (P-Q) relationships, segmental resistance with arterial and venous occlusion (AVO), and sensitivity to drugs. At final thoracotomy, mean LLL pulmonary arterial pressure (Ppa) was 23.2 +/- 4.3 mmHg compared with 11.9 +/- 0.9 in the right lung (P less than 0.05); two animals had LLL Ppa of 41 and 48 mmHg. The LLL artery and vein were cannulated, and pressure-flow (P-Q) and AVO measurements were made and compared with previous control LLL (n = 11) and contralateral right lower lobe (RLL, n = 5). Responses to serotonin, histamine, and vasodilators (diltiazem and isoproterenol) were evaluated. Comparisons of morphometric measurements were made between LLL and RLL. We found a significant increase in arterial resistance as measured with AVO and a hypersensitivity to serotonin in the shunt LLL, without changes in total pulmonary vascular resistance or P-Q measurements; vasodilators had a small effect only in the hypertensive lobes. Our data suggest that chronic shunts to the pulmonary circulation increase arterial resistance and sensitivity to serotonin, even in the absence of discernible morphometric changes, and that vasoconstriction may be an important precursor to the development of morphological lesions.

Animals↗
PubMed1985

Chylopericardium following cardiac surgery.

Chylopericardium is one of the rarest complications of cardiac surgery. The authors report only the 19th case, that of a 12-year-old boy. The chylopericardium developed after an aortic valvotomy, even though the retropericardial portion of the mediastinum was entered only to pass a tape around the ascending aorta. Etiologic factors are directly or indirectly related to injury to the thoracic duct or tis tributaries. Treatment initially is conservative, consisting of adequate pericardial drainage and a low-fat, medium-chain triglyceride diet. If this fails, the appropriate operative procedure is carried out.

Aortic Valve↗
PubMed1984

Catastrophic hemorrhage during redo sternotomy.

This paper reviews the attitude of 131 surgeons to the performance of a second sternotomy incision and assesses 144 severe hemorrhages that occurred as the sternotomy was being done. Eighty-eight percent of the hemorrhages occurred in situations in which the pericardium had not been closed at the first operation. From these events and the present attitude of surgeons responding to our questionnaire, we offer advice on the management of second sternotomies and on the management of hemorrhage when it occurs.

Catastrophic Illness↗
PubMed1984

Surgery for postinfarction left ventricular aneurysm: prognosis and long-term follow-up.

To identify preoperative indicators of outcome following surgery for postinfarction left ventricular aneurysm, the authors have analysed the clinical course of 67 consecutive patients who underwent operation from 1970 to 1982. Follow-up extended to 12 years (mean 4.6 years) and was 97% complete. Postoperative mortality was 8.9%. Factors that were associated with a significantly (p less than 0.05) increased risk of early death included emergency surgery, the presence of ventricular arrhythmias preoperatively and a left ventricular end-diastolic pressure of more than 25 mm Hg on cardiac catheterization. Patients who underwent myocardial revascularization concomitantly had a lower mortality (7.1% v. 18.2% for aneurysmectomy alone), decreased postoperative morbidity and increased longevity. Marked functional improvement was noted in all groups. Actuarial survival (including operative mortality) was 66% at 6 years, and was significantly (p less than 0.05) better in patients operated upon for angina (83.6% +/- 8.1%) than in those operated upon for congestive heart failure (53% +/- 13%). The authors conclude that the most important predictor of outcome following postinfarction aneurysm surgery is the preoperative hemodynamic status of the left ventricle. Since functional recovery and prognosis after operation have been excellent, an aggressive surgical approach to symptomatic left ventricular aneurysms is warranted.

Adult↗
PubMed1983

Electrical behavior of the heart following high-potassium cardioplegia.

The electrical activity of the heart was studied in 25 patients undergoing elective coronary artery bypass grafting. Simultaneous surface electrocardiograms and bipolar atrial electrograms were monitored continuously from the onset of cardioplegic arrest until normal sinus rhythm was reestablished. Several observations were made. (1) Administration of cardioplegia promptly induced and maintained ventricular arrest in all patients. (2) Atrial activity was seen in 23 patients during global ischemia. (3) Following unclamping, the first sustained rhythm was atrial in 22 patients and was associated initially with high-grade atrioventricular block progressing to 1:1 conduction after a mean reperfusion time of 23 minutes. (4) The time required for complete electrical recovery varied directly with the cross-clamp time and the amount of cardioplegic solution used. (5) Only 3 patients required ventricular defibrillation. (6) In the postoperative period, supraventricular tachyarrhythmias developed in 6 patients. Their occurrence appeared to be related to prolonged atrial activity during the cross-clamp period. Although cardioplegia administration maintained ventricular arrest, sustained atrial activity often was present, perhaps implying inadequate atrial protection and predisposing to atrial arrhythmias. Normal sinus rhythm was reestablished spontaneously in all patients. The atrial electrogram proved essential in the precise intraoperative recognition of cardiac rhythm.

Adult↗
PubMed1983

Persistent atrial activity during cardioplegic arrest: a possible factor in the etiology of postoperative supraventricular tachyarrhythmias.

We assessed the relationship between the duration of atrial activity during the cross-clamp period and the postoperative occurrence of supraventricular tachyarrhythmias in 50 patients undergoing elective coronary bypass operation. The atrial electrical activity was monitored continuously by means of a bipolar atrial electrogram from the onset of cardioplegic administration until removal of the aortic cross-clamp. While ventricular arrest was induced promptly and maintained in all patients, sustained atrial activity was observed in 44 out of 50 patients during the cross-clamp period. In the postoperative period, supraventricular tachyarrhythmias developed in 15 patients (Group 1). Thirty-five patients (Group 2) were free from such tachyarrhythmias. There was no significant difference between the two groups with respect to cross-clamp time, bypass time, amount of cardioplegic solution used, or number of grafts per patient. The mean duration of atrial activity during cardioplegic arrest, however, was significantly longer in Group 1 than in Group 2 (46 +/- 4.7 minutes versus 22.6 +/- 4.0 minutes, respectively, p less than 0.001). None of the 6 patients in whom atrial activity was completely abolished experienced supraventricular tachyarrhythmias. The strong correlation observed between the duration of atrial activity during cardioplegic arrest and the incidence of postoperative supraventricular tachyarrhythmias suggests the possibility that these arrhythmias may be a manifestation of inadequate atrial protection during global myocardial ischemia.

Arrhythmias, Cardiac↗
PubMed1983

Atrial electrical activity and its suppression during cardioplegic arrest in pigs.

Right atrial electrical activity and myocardial temperatures of all four chambers were monitored during a 1 hour period of cardioplegic arrest in 20 pigs subjected to different methods of venous cannulation and cardiac cooling. Myocardial protection was provided by systemic hypothermia (28 degrees C) and intermittent intra-aortic administration of cold (4 degrees C) hyperkalemic (20 mEq/L) crystalloid cardioplegia. The use of a single right atrial cannula for venous drainage was associated with sustained atrial activity (50 +/- 5.5 minutes) during cardioplegic arrest and the warmest right atrial (27 degrees +/- 0.2 degrees C) and right ventricular (20.5 degrees +/- 0.4 degrees C) temperatures. Separate caval cannulation with snaring and right atrial venting decreased right atrial and ventricular temperatures marginally (25.3 degrees +/- 0.5 degrees C and 19.1 degrees +/- 0.4 degrees C, respectively, p less than 0.05) but did not significantly alter the duration of atrial electrical activity (42.2 +/- 2.5 minutes, p greater than 0.05). Addition of an extracavitary right atrial drip of cold (4 degrees C) saline, 750 ml for the 1 hour aortic clamping period, reduced right atrial temperature (22.8 degrees +/- 0.4 degrees C) and activity (24.8 +/- 6.3 minutes) to a significant extent. Intracavitary irrigation of the right atrium with cold saline, in the presence of snared double caval cannulas, decreased right atrial and ventricular temperatures most dramatically (17.0 degrees +/- 0.5 degrees C and 17.5 degrees +/- 0.3 degrees C, respectively, p less than 0.05), reduced the duration of atrial electrical activity by 84% (to 8 +/- 3.9 minutes, p less than 0.01), and diminished the total number of atrial contractions per hour of aortic clamping by 88%. It is concluded that intracavitary right atrial cooling with separate snared caval cannulation is the most effective method of ensuring atrial inactivity and prolonged right heart hypothermia during cardioplegic arrest.

Animals↗
PubMed1982

The human touch.

Explore the source record for details and available documents.

Communication↗
PubMed1982

Staged repair of ectopia cordis.

Ectopia cordis is a challenging congenital anomaly that generally has defied repair because of the magnitude of the deformity and the associated defects, particularly the intracardiac anomalies. We were fortunate to be presented with a boy who had successfully undergone an operation on the day of his birth to provide skin coverage over his bare ectopic heart. Subsequent studies disclosed no intracardiac anomalies. This paper describes the second stage of his repair designed to place the heart within the thorax and construct a bony shield anterior to it.

Follow-Up Studies↗
PubMed1981

Congenital valvular aortic stenosis: surgical management and long-term results.

Case histories of 50 consecutive infants and children ith congenital valvular aortic stenosis treated at The Montreal Children's Hospital during the past 16 years were reviewed in order to determine the efficacy of the initial treatment as well as the long-term results. The operative technique employed was to incise fused commissures out almost to the anulus without causing aortic insufficiency, but often the accomplishment was limited by valve anatomy or cusp dysplasia. Six of the seven operative deaths occurred in infants. Eight to 16 year follow-up on the first 25 survivors revealed one late death, four "good" results, five aortic valve replacements, and three second valvotomies. Ten patients have recurrent aortic stenosis and two have moderate aortic insufficiency. Aortic valvotomy is a palliative operation, and about a third of the children operated upon will require a second operation within 10 years.

Adolescent↗
PubMed1981

Surgical treatment of the dilated aortic root in a child with Marfan's syndrome.

Life-threatening cardiovascular manifestations of Marfan's syndrome are rare in young children. The authors report the case of a 4 1/2-year-old girl with Marfan's syndrome who had a large aneurysm of the ascending aortic valve replaced and both coronary arteries implanted into a prosthetic graft (Bentall's procedure). Other published reports of children with aortic aneurysms due to Marfan's syndrome are reviewed.

Aortic Aneurysm↗
PubMed1981

Right coronary-left ventricular fistula mimicking aortic valve insufficiency in infancy.

Two infants had large communications between the right coronary artery just distal to its origin and the cavity of the left ventricle. The findings were essentially those of aortic insufficiency. In the first patient operation was delayed until there was secondary aortic insufficiency resulting from dilatation of the aortic root. The second patient was operated upon in infancy, and abolition of the fistula has relieved the clinical situation. Surgeons should recognize that isolated congenital aortic valve insufficiency has not been reported to our knowledge. Therefore, infants who appear to have this condition should undergo thorough angiographic studies which likely will reveal a remediable situation. A surgical approach for the type of fistula described herein is presented.

Adolescent↗
PubMed1981

Prosthetic valve infections.

Over a 10-year period, 25 patients were treated for prosthetic valve infections: 13 infections were of early onset (within 2 months of valve insertion) and 12 of late onset. Of the latter group 11 patients survived, 6 without reoperation. By contrast, 6 of the 13 with early infections died, 5 of them being among the group of 9 patients who did not undergo reoperation. Vegetations were found on most valves at autopsy or reoperation; they are a major threat to these patients. The authors believe that the mortality for early prosthetic valve infections can be reduced only by earlier prosthetic valve removal and replacement.

Anti-Bacterial Agents↗