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Biomedical subjects

M J Buckley

Publications and source records attributed to M J Buckley.

At least 19 recordsLinked to original sources
PubMed1992

Intraoperative aortic dissection.

Intraoperative aortic dissection is a rare but potentially fatal complication of open heart operations. If the dissection is promptly recognized and repaired, however, the outcome may be significantly better. In this study, we reviewed the hospital records of patients with dissection of the aortic arch occurring as a complication of a cardiac operation at Massachusetts General Hospital and Mt. Auburn Hospital from January 1980 through June 1990. During this period, 14,877 surgical procedures with the use of cardiopulmonary bypass and aortic cannulation were performed, and 24 patients (0.16%) with iatrogenic aortic dissection were identified. Dissection was discovered intraoperatively in 20 patients and postoperatively after complications developed in 4. Of the 20 patients whose injuries were discovered intraoperatively and repaired, 4 (20%) died. Of the 4 whose injuries were discovered after operation, 2 (50%) died. The primary cause of death was ventricular dysfunction resulting from myocardial ischemia. Dissections originated at the aortic cannulation site in 10 patients, at the cross-clamp site in 8, at the site of the partial-occlusion clamp in 7, at the proximal anastomosis in 1 patient, and as a result of direct injury in 1. Three of these patients had simultaneous injuries at the aortic cannulation site and at the heel of the partial-occlusion clamp. Two techniques of repair were used: primary repair and patch or tube graft insertion. There were two deaths in the patients who underwent primary repair and four deaths in patients requiring graft replacement. Although it is uncommon, intraoperative aortic dissection can be a lethal complication of cardiac operations.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Postinfarct ventricular septal defect repair: effect of coronary artery bypass grafting.

Between June 1968 and April 1991, 75 patients who had undergone coronary angiography underwent repair of a postinfarction ventricular septal defect. Group 1 (n = 33) includes patients who had two- or three-vessel serious (> 75% narrowing) proximal coronary artery disease and underwent complete revascularization in addition to repair of the ventricular septal defect. Group 2 (n = 19) patients also had two- or three-vessel coronary artery disease but bypass grafting was not performed; only the ventricular defect was repaired. Group 3 (n = 23) patients had only single-vessel coronary artery disease that corresponded to the region of the infarct; they underwent ventricular septal defect repair only. Follow-up of hospital survivors was 96% complete at a mean of 86.2 months (range, 1 to 288 months). Hospital mortality after ventricular septal defect repair was 21.2% in the cohort with bypassed coronary artery disease (group 1), 26.3% in those with unbypassed disease (group 2), and 26.1% in those with only single-vessel coronary artery disease (group 3) (p = 0.88). With follow-up after 5 and 10 years, the actuarial survival was 72.2% +/- 8% and 47.8% +/- 10%, respectively, in the bypassed group, 29.2% +/- 11% and 0%, respectively, in the unbypassed group, and 52.2% +/- 10% and 36.5% +/- 11%, respectively, in the cohort with single-vessel disease. Bypassing associated coronary artery disease significantly increased long-term survival when compared with patients with unbypassed coronary artery disease (p = 0.0015).

Aged↗
PubMed1992

Blunt injuries of the thoracic aorta.

We managed 51 patients with thoracic aortic injuries caused by blunt trauma between 1977 and 1990. Forty-nine injuries were located in the upper descending aorta and one each in the ascending aorta and aortic arch. Three patients arrived moribund and underwent thoracotomy for resuscitation, and all died. The diagnosis was confirmed by aortography in 48. One patient died of aortic rupture, 1 died of hypoxemia, and 1 refused operation and died. Forty-four patients had aortic repair, 42 with graft insertion. Gott shunts were placed in 23 with 3 cases of paraplegia (13%). Simple cross-clamping was used in 19 with 1 case of paraplegia (5.2%). We found statistically significant differences between the cross-clamp times of patients without paraplegia compared with those in whom paraplegia developed in both the shunt and no-shunt groups. Logistic regression analysis showed that the only factor significantly associated with paraplegia was cross-clamp time. There were two postoperative deaths (4.4%). Seven patients had medical therapy initially and aortic repair was delayed to allow other injuries to stabilize. Before aortic repair, 18 patients had intraarterial pressure monitoring and 34 received beta-blockers or antihypertensive drugs. We conclude that aortic repair with graft insertion is usually successful in nonmoribund patients, simple cross-clamping is associated with a relatively low risk of paraplegia, the incidence of paraplegia is directly associated with the duration of cross-clamp time, and selected patients can be managed medically while awaiting aortic repair.

Adolescent↗
PubMed1991

The safety of intraaortic balloon pump catheter insertion through suprainguinal prosthetic vascular bypass grafts.

To determine the safety of intraaortic balloon pump catheter insertion for critical coronary ischemia through suprainguinal prosthetic bypass grafts, we examined our experience of 19 intraaortic balloon pumps placed through grafts in 17 patients by means of surgical exposure (8) or the percutaneous (11) approach. Fourteen intraaortic balloon pumps were placed through matured grafts at a time remote (2 to 13 years; mean, 7 years) from their vascular bypass surgery. Five were inserted through nonmatured grafts during the same hospitalization as their vascular reconstructive surgery (1 to 12 days; mean, 4 days). One patient, a day after an aortoiliac bypass, died during an urgent, surgical intraaortic balloon pump insertion for cardiogenic shock. All other patients had prompt reversal of their cardiac ischemia. Decreased limb perfusion developed during use of the intraaortic balloon pump in three patients, all of whom had their intraaortic balloon pump placed percutaneously through mature grafts. Two of these required surgical thrombectomy. Ten intraaortic balloon pump insertions in eight patients survived the hospitalization and were followed for a mean of 24 months (range, 2 weeks to 64 months). No localized groin or graft infections were identified. No bleeding complications or pseudoaneurysms occurred. Thus in patients with unstable, severe, cardiac disease, intraaortic balloon pumps can be safely placed through indwelling suprainguinal bypass grafts.

Aged↗
PubMed1990

Preclinical evaluation of an "instant" 99mTc-labeling kit for antibody imaging.

This communication presents information on the quality and stability of a new conjugate of 99mTc to an anticancer antibody fragment and results of animal imaging and distribution studies. Clinical studies have proved that this labeled antibody can image tumors within 2 hours of i.v. injection. It is produced using an "instant kit," merely requiring addition of [99mTc]pertechnetate to a lyophilized vial containing the fragment and a pertechnetate-reducing agent. Within 5 min of addition of pertechnetate to the vial containing the fragment, [99mTc]pertechnetate is reduced and quantitatively bound to an intrinsic high-affinity receptor present in the Fab'. The Fab'-bound 99mTc is completely stable to challenge with diethylenetriaminepentaacetic acid and human serum albumin. Minimal oxidation and release of 99mTc bound to the fragment were observed when the labeled fragment was incubated for 24 h at 37 degrees C. Animal biodistribution studies were consistent with the known metabolic elimination of a radiolabeled Fab' fragment by the kidney. Tumor localization studies in athymic nude mice bearing xenografts of human colonic carcinoma (GW-39) predicted the positive results later demonstrated in clinical studies.

Animals↗
PubMed1990

The effects of mechanical strain on osteoblasts in vitro.

The effect of mechanical strain on bone is important to the field of oral and maxillofacial surgery. Oral and maxillofacial surgeons are involved on a daily basis with problems including alveolar ridge resorption, implant stability, craniofacial growth, and bone resorption related to trauma and pathology. To understand and control these effects on bone, it is important to examine the effects of mechanical strain on the osteoblasts. This series of experiments provides the changes in alkaline phosphatase, collagen synthesis, and protein synthesis in osteoblast-like cell subjected to mechanical strain.

Alkaline Phosphatase↗
PubMed1990

Surgical coronary revascularization in survivors of prehospital cardiac arrest: its effect on inducible ventricular arrhythmias and long-term survival.

In a selected subgroup of 50 survivors of cardiac arrest, the impact of surgical myocardial revascularization on inducible arrhythmias, arrhythmia recurrence and long-term survival was examined. The effects of several clinical, angiographic and electrophysiologic variables on arrhythmia recurrence and survival were also analyzed. All patients had a prehospital cardiac arrest and severe operable coronary artery disease and underwent myocardial revascularization. Preoperative electrophysiologic study was performed in 41 patients; 33 (80%) had inducible ventricular arrhythmias. Of 42 patients studied off antiarrhythmic drugs postoperatively, 19 (45%) had inducible ventricular arrhythmias. Thirty patients with inducible arrhythmias preoperatively underwent postoperative testing off antiarrhythmic drugs; arrhythmia induction was suppressed in 14 (47%). By multivariate analysis, the induction of ventricular fibrillation at the preoperative electrophysiologic study was the only significant predictor of induced ventricular arrhythmia suppression by coronary surgery (p less than 0.001). Inducible ventricular fibrillation was not present postoperatively in any of the 11 patients who manifested this arrhythmia preoperatively. In contrast, inducible ventricular tachycardia persisted in 80% of patients in whom preoperative testing induced this arrhythmia. Patients were followed up for 39 +/- 29 months. There were four arrhythmia recurrences; one was fatal. There were three nonsudden cardiac deaths and three noncardiac deaths. By life-table analysis, 5 year survival, cardiac survival and arrhythmia-free survival rates were 88%, 98%, and 88%, respectively. Depressed left ventricular ejection fraction and advanced age were predictive of death (p = 0.015 and 0.026, respectively) and cardiac death (p = 0.037 and 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1990

Orbital emphysema causing vision loss after a dental extraction.

The use of high-speed air-cooled rotary cutting instruments is common in dental practices. When used near open wounds, the forced air can lead to subcutaneous emphysema and involvement of vital structures. This case highlights the unfortunate episode of orbital emphysema with optic nerve damage after a pneumatically cooled drill was used in the removal of a mandibular second molar.

Adult↗
PubMed1990

Hemodilution in orthognathic surgery.

The patient population for elective orthognathic surgery usually comprises young, healthy patients, in whom homologous blood transfusions should be avoided. Homologous transfusion poses substantial, potentially preventable risks to this patient population. In addition to autologous predonation, acute intentional hemodilution is an alternative that potentially avoids the use of homologous blood. Indications and contraindications for its use as well as initial results in two patients are presented. Further data and experience are required before this technique can be recommended for routine use.

Adolescent↗
PubMed1990

Late results with Carpentier-Edwards porcine bioprosthesis.

From 1977 to 1984, 429 patients underwent aortic valve replacement (AVR), and 339 underwent mitral valve replacement (MVR) with a Carpentier-Edwards bioprosthesis. Early mortality for AVR was 4.6% (isolated AVR, 1.9%) and for MVR was 5.3% (isolated MVR, 4.1%). Follow-up was 99.3% complete at a mean of 5.9 years. Actuarial event-free rates at 10 years for AVR and MVR were, respectively, 1) for structural valve deterioration, 91.4 +/- 3.2% versus 75.1 +/- 4.0% (p less than 0.01); 2) for nonstructural dysfunction, 100% versus 97.8 +/- 1.6% (p = NS); 3) for thromboembolism, 90.6 +/- 2.3% versus 87.3 +/- 2.6% (p = NS); 4) for anticoagulant-related bleeding, 95.3 +/- 1.1% versus 88.6 +/- 2.4% (p = 0.05); 5) for endocarditis, 87.8 +/- 5.7% versus 90.6 +/- 2.4% (p = NS); 6) for reoperation, 91.0 +/- 2.5% versus 74.4 +/- 3.7% (p less than 0.01); 7) for valve-related mortality, 76.1 +/- 6.9% versus 71.4 +/- 5.2% (p = 0.01); 8) for permanent physical impairment, 85.0 +/- 3.0% versus 71.5 +/- 3.6% (p less than 0.01); and 9) for combined operative mortality, valve-related mortality, and reoperation, 68.7 +/- 6.4% versus 51.5 +/- 4.9% (p = 0.01). No structural valve dysfunction was observed in any AVR patient whose valve was inserted after age 70. Age at operation was the only factor that predicted structural valve deterioration (p less than 0.01).

Actuarial Analysis↗
PubMed1989

Stress shielding effect of rigid internal fixation plates on mandibular bone grafts. A photon absorption densitometry and quantitative computerized tomographic evaluation.

The use of rigid internal fixation reconstruction plates in combination with bone grafts provides many advantages in mandibular reconstruction. These advantages include ease of adaptability at the time of surgery as well as immediate postoperative function for the patient. Disadvantages may include a "stress shielding" or disuse osteoporosis effect on the underlying bone graft as a result of the rigidity of the reconstruction plate. This study evaluated the stress shielding effects on bone grafts in primate mandibles. Bilateral bone grafts stabilized with rigid fixation plates were performed in 4 Macaca fascicularis monkeys. Three months after the bone grafting procedure one plate was removed from each monkey. The monkeys were then killed 1, 4, 6 and 8 months after plate removal. Photon absorption densitometry and computerized tomography were used to evaluate stress shielding. The results of this study indicate that the stress shielding effect occurs if the plate is not removed from the area of bone grafting postoperatively.

Absorptiometry, Photon↗
PubMed1989

Histomorphometric evaluation of stress shielding in mandibular continuity defects treated with rigid fixation plates and bone grafts.

Histomorphometric techniques were used to evaluate the stress shielding effect in bilateral bone grafts in 4 Macaca fascicularis monkeys. Bilateral continuity defects were created and grafted by replacing the resected portion of the mandible and iliac crest bone into the defect area. Both sides were plated with rigid internal fixation plates. Three months after bone grafting, the plate was removed from one side while the other plate was left in place. The animals were sacrificed at 1, 4, 6, and 8 months after plate removal and the grafted areas removed for histomorphometric analysis. This study documents decreased bone volume as well as smaller interlabel width on the plated side, suggesting a stress shielding effect as a result of the rigid internal fixation plate.

Animals↗
PubMed1989

Complications of orthognathic surgery: a comparison between wire fixation and rigid internal fixation.

This retrospective review compares the results of using rigid internal fixation (RIF) and wire fixation for orthognathic surgery patients. The records of two groups of demographically similar patients who underwent comparable surgery, performed by the same four attending surgeons at the same institutions during the same time period (1983 to 1986), were evaluated for complications and unanticipated treatment results. The most striking finding of this study is the general similarity between the two groups. However, differences in frequency of excessive weight loss and persistent restriction of mandibular opening suggest a benefit from early mobility of the mandible that comes with RIF. Because there was no concomitant increase in complications or unexpected results of treatment, the introduction of RIF for orthognathic surgery may offer patients some potential advantages.

Humans↗
PubMed1986

Influence of coronary artery obstruction on cardiac prostaglandin metabolism during experimental cardioplegic arrest.

In order to test the influence of coronary artery obstruction on cardiac prostaglandin metabolism during surgically induced cardioplegia (CP), we have measured transcardiac veno-arterial gradients of prostacyclin and thromboxane A2 (TXA A2) during experimental canine cardiopulmonary bypass. Cardiac arrest was induced by infusion of 500 ml of hypothermic (8 degrees C), hyperkalemic (25 meq) crystalloid CP solution into the aortic root with (group I) and without (group II) occlusion of the left anterior descending artery (LAD). After 30 minutes of cardioplegic arrest the LAD occlusion in group I was released and a second set of CP infusion was applied in both groups. Transcardiac gradients were obtained 5 seconds after onset of the first and second CP washouts. Significant prostacyclin and TXA A2 gradients were observed at both times. Prostacyclin gradients did not differ between group I and group II. In contrast, TXA A2 gradients were significantly higher during the second CP washout in group I as compared to the unoccluded group (group I 918 +/- 221, group II 244 +/- 144 pg/ml, p less than 0.05). The results of our study suggest that cardiac TXA A2 metabolism during cardioplegic arrest is increased distal to a coronary artery obstruction. Cardiac TXA A2 production might contribute to the increased ischemic myocardial injury observed in this setting.

6-Ketoprostaglandin F1 alpha↗
PubMed1979

Survival following mitral valve replacement for mitral regurgitation due to coronary artery disease.

Forty-six patients who underwent mitral valve replacement for mitral regurgitation due to coronary artery disease during 1970-1975 were identified. Forty patients underwent aortocoronary bypass procedures at the same operation. The survival rate at the fourth postoperative year was 73% in the 22 patients in whom the preoperative left ventricular ejection fraction exceeded 0.35, 38% in the 16 patients in whom the preoperative left ventricular ejection fraction was 35% or less, and 25% in the eight patients in whom aneurysmectomy was performed at the time of mitral valve replacement (p less than 0.05 for the former group compared to the latter two groups). Heart failure, present preoperatively in 41 patients, was improved in most of the long-term survivors. Neither the angiographic extent of coronary artery disease nor whether mitral valve replacement was performed in the acute (within 2 months in 13 patients) or chronic phase of myocardial infarction were distinctly correlated with survival.

Aged↗
PubMed1979

Safe early revascularization for continuing ischemia after acute myocardial infarction.

Early revascularization following myocardial infarction (MI) is reported to have a high risk of extension of and hemorrhage into infarction with resulting high mortality and morbidity. To evaluate this issue, 80 post-MI patients (aged 32-74 years) with unstable angina pectoris resistant to maximal medical therapy were reviewed. All patients underwent early uncomplicated angiography and subsequent revascularization; 55 (69%) were less than 10 days post-MI, and 25 (31%) were 10-30 days post-MI. Intraaortic balloon pumping was required in 72% for relief of intractable angina or hemodynamic instability. Of the 80 patients, 19% had single vessel disease (VD), 31% double VD, and 50% triple VD. The mortality rate from coronary bypass surgery was 7/80 (8.8%), with four cardiac and three noncardiac deaths. Two patients suffered a perioperative MI (2.5%). At a mean follow-up period of 33 months, there had been only one late death and one recurrent nonfatal MI; 96% of the patients had no significant angina. In patients with continuing ischemia immediately after MI, myocardial revascularization can be safely performed without further injury to the myocardium, and with excellent long-term results.

Adult↗