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Biomedical subjects

D E Cameron

Publications and source records attributed to D E Cameron.

At least 19 recordsLinked to original sources
PubMed1992

Surgical treatment of postinfarction ventricular septal defect with aortic stenosis.

A 69-year-old man with an acute postinfarction ventricular septal defect was also found to have aortic stenosis. Successful management required closure of the postinfarction ventricular septal defect and replacement of the stenotic aortic valve. The contribution of aortic stenosis to the cause of the infarction and the postinfarction ventricular septal defect, as well as the implications for surgical management, are discussed.

Aged↗
PubMed1992

Hypothermic circulatory arrest as a surgical adjunct: a 5-year experience with 60 adult patients.

As a surgical adjunct, the technique of hypothermic circulatory arrest (HCA) is well established in pediatric cardiac surgery but is used less frequently in adults. This study was undertaken to review the application, utility, and safety of HCA in adult surgery at a single institution. Between January 1985 and October 1990, 60 adult patients (greater than 18 years old) underwent surgical procedures that included HCA. There were 30 men and 30 women; mean patient age was 56.4 years (range, 20 to 81 years). Operative procedures were thoracic aortic aneurysm repair (35 patients, 58%), resection of intraabdominal malignancy (15 patients, 25%), coronary artery bypass (4 patients, 7%), and other miscellaneous procedures (6 patients, 10%). Eighty-two percent of the procedures were elective, whereas 18% were emergencies. Mean circulatory arrest time was 28.5 minutes (range, 2 to 64 minutes). Operative mortality was 15%; by multivariate analysis, risk factors for death included prolonged cardiopulmonary bypass time (p less than 0.05), higher post-HCA rectal temperature (p less than 0.05), and intraoperative hypotension (p less than 0.001). Patient age, sex, emergency status, duration of HCA, and perfusion variables on cardiopulmonary bypass did not predict operative mortality. The incidence of perioperative neurologic injury was 15%. The only risk factor for neurologic injury was intraoperative hypotension (p less than 0.05). One- and 3-year actuarial survival for patients undergoing operation on the heart or great vessels was 75.9% and 70%, respectively, whereas patients with intraabdominal malignancy had 75% and 23.4% 1- and 3-year survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Pulmonary embolism in the cardiac surgical patient.

Pulmonary embolism (PE) is thought to occur infrequently after cardiac operations, possibly because systemic heparinization during cardiopulmonary bypass prevents deep vein thrombosis. This retrospective study was undertaken to determine the actual incidence of PE after cardiac operations and to identify risk factors. Between January 1, 1985, and December 31, 1989, 5,694 adult patients (greater than 18 years old) had open heart operations at the Johns Hopkins Hospital. Thirty-two patients (20 men and 12 women) had PE within 60 days of operation, an overall PE incidence of 0.56%. The diagnosis of PE was established by ventilation/perfusion scan, pulmonary angiogram, or autopsy. Mortality among patients with PE was 34%. Using a case-control method, preoperative and postoperative risk factors for PE were identified by multivariate and multiple logistic regression analyses. Preoperative risk factors included bed rest (p less than 0.003), prolonged hospitalization before operation (p less than 0.004), and cardiac catheterization performed through the groin within 15 days before operation (p less than 0.01). Post-operative risk factors were congestive heart failure (p less than 0.008), prolonged bed rest (p less than 0.05), and deep vein thrombosis (p less than 0.03). This study demonstrates that PE is an unusual complication after cardiac operations, has a high mortality rate, and is often related to perioperative immobility and recent groin catheterization. These results also suggest that minimizing preoperative hospital stay may be important in PE prophylaxis.

Bed Rest↗
PubMed1992

Demonstration of cytomegalovirus nucleic acids in the coronary arteries of transplanted hearts.

Cytomegalovirus (CMV) infection has been associated with the development of accelerated arteriosclerosis in heart transplant recipients. This association prompted the authors to examine, using in situ hybridization techniques, the coronary arteries of 19 patients who had received heart transplants for the presence of CMV nucleic acids. Two probes were employed on formalin-fixed paraffin-embedded tissues. The first was an S35-labeled nick translated probe derived from CMV DNA. CMV nucleic acids were identified in the arterial intima of 5 (45%) of 11 transplanted hearts examined with this probe. Hybridization to cells morphologically consistent with endothelial cells, lymphocytes, and smooth muscle cells was identified. Hybridization was not detected in any of the hearts when a control probe, a vector without CMV DNA, was employed. The second probe that was used was a tritium-labeled strand-specific ribo-probe derived from the immediate early (IE1) gene of CMV. Using this second probe, hybridization was detected in the coronary arteries of three of five hearts that were positive with the DNA probe, in one of the hearts that was negative with the DNA probe, and in three (38%) of eight additional transplanted hearts. The pattern of hybridization was the same as that seen with the DNA probe, and no hybridization was detected when a control sense probe for the IE1 gene of CMV was employed. These results suggest that CMV nucleic acids are present in the coronary arteries of heart transplant recipients.

Adolescent↗
PubMed1992

Cardiopulmonary bypass and the blood-brain barrier. An experimental study.

The diffuse inflammation produced by cardiopulmonary bypass might disrupt the blood-brain barrier and lead to the transient neurologic dysfunction occasionally seen after cardiac operations. To evaluate this possibility, blood-brain barrier integrity was measured by carbon 14-aminoisobutyric acid tracer technique after 2 hours of cardiopulmonary bypass in piglets. Six animals were cooled to 28 degrees C on cardiopulmonary bypass and then rewarmed to 38 degrees C before carbon 14-aminosisobutyric acid was injected intraarterially. A control group of six animals underwent median sternotomy and heparinization but were not placed on cardiopulmonary bypass. Blood-to-brain transfer coefficients for carbon 14-aminosisobutyric acid were calculated for multiple brain regions; higher coefficients reflect greater flux of carbon 14-aminosisobutyric acid and suggest loss of blood-brain barrier integrity. The brain regions examined and their transfer coefficients (cardiopulmonary bypass versus control mean +/- standard error of the mean ml/gm/min) were middle cerebral artery territory cortex (0.0032 +/- 0.0002 versus 0.0030 +/- 0.0002; p = 0.42), diencephalon (0.0031 +/- 0.0003 versus 0.0029 +/- 0.0002; p = 0.50), midbrain (0.0028 +/- 0.0002 versus 0.0027 +/- 0.0002; p = 0.86), cerebellum (0.0036 +/- 0.0003 versus 0.0029 +/- 0.0002; p = 0.22), and spinal cord (0.0035 +/- 0.0003 versus 0.0041 +/- 0.0008; p = 0.48). There were no significant differences in transfer coefficients between animals placed on cardiopulmonary bypass and control animals in any brain region examined. The pituitary gland lacks a blood-brain barrier and had a correspondingly high coefficient in control animals and those undergoing cardiopulmonary bypass (0.077 +/- 0.012 versus 0.048 +/- 0.008; p = 0.07). Two hours of moderately hypothermic cardiopulmonary bypass does not disrupt the blood-brain barrier.

Aminoisobutyric Acids↗
PubMed1992

Absorbable suture improves growth of venous anastomoses.

Growth of vascular anastomoses is desirable in pediatric vascular surgery, especially in pediatric organ transplantation. Although absorbable suture has been shown to be superior to nonabsorbable suture in permitting growth of arterial anastomoses, the optimal suture material for venous anastomoses has not been established. To examine this in a porcine model, we performed bilateral primary end-to-end anastomoses of transected external jugular veins in 10, 4-week-old piglets. In each piglet one anastomosis was constructed with continuous absorbable 8-0 polyglyconate suture, whereas the contralateral anastomosis was constructed with continuous nonabsorbable 8-0 polypropylene suture. After 6 months the veins were excised, pressure fixed at 15 mm Hg for 2 hours, and examined grossly and histologically. Vein diameter was measured by contrast radiography at the anastomosis and 1 cm proximal and distal to the anastomosis. Vein cross-sectional area 1 cm from the anastomosis was similar in the two groups: polyglyconate 95.7 +/- 12.3 mm2 versus polypropylene 95.3 +/- 9.7 mm2. However, polyglyconate anastomoses had greater cross-sectional area (polyglyconate 72.8 +/- 7.9 mm2 vs polypropylene 51.8 +/- 6.0 mm2; p < 0.05). In addition, at 6 months polyglyconate anastomoses had a greater percentage of growth (polyglyconate 207% vs polypropylene 118%; p < 0.05) compared with native vein cross-sectional area (23.7 +/- 0.39 mm2) from control pigs at 4 weeks of age. On histologic examination, polyglyconate had dissolved entirely in six cases and was present but in varying degrees of dissolution in the other four; in contrast, polypropylene was identifiable at all anastomoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1992

Successful twenty-four-hour lung preservation with donor core cooling and leukocyte depletion in an orthotopic double lung transplantation model.

Donor core cooling with cardiopulmonary bypass is a valid method of clinical lung preservation. However, organ ischemia with this method is still limited to short-term intervals. Since circulating leukocytes participate in postischemic injury through the release of oxygen-derived free radicals, we examined whether leukocyte depletion by mechanical filtration could extend ischemic tolerance of the lung during preservation and subsequent double lung transplantation. Bovine donor lungs were preserved by donor core cooling (10 degrees to 15 degrees C) with cardiopulmonary bypass. Donor lungs were removed, stored in 4 degrees C donor blood for 24 hours, and transplanted. Graft function was studied for 6 hours after transplantation. Group 1 animals (n = 6) underwent standard cardiopulmonary bypass with whole blood for donor and recipient procedures. In group 2 (n = 6), leukocyte filters were incorporated into the cardiopulmonary bypass circuit in both donor and recipient operations. In group 2 recipient animals leukocyte counts decreased to 3% of mean baseline values and remained low during the experiment. Postischemic lung function (assessed by systemic arterial oxygenation, pulmonary artery pressure, pulmonary vascular resistance, airway pressure, lung water content, and end-point histologic characteristics) was significantly better preserved in the animals with leukocyte depletion. Leukocyte depletion by mechanical filtration in both donor and recipient improves the ischemic tolerance of the lung beyond that provided by donor core cooling alone, resulting in excellent lung function after 24 hours of ischemia.

Animals↗
PubMed1991

Current indications, risks, and outcome after pericardiectomy.

A retrospective analysis of the records of 60 patients who underwent pericardiectomy over a 10-year period (1980 to 1990) at The Johns Hopkins Hospital was performed. Indications for operation were effusive disease in 24 patients and constriction in 36 patients. Six patients (10%) with pericardial effusion had pain as the primary symptom necessitating intervention. The operative approach for pericardiectomy was median sternotomy in 52 patients (4 patients required cardiopulmonary bypass) and left anterior thoracotomy in 8 patients. Nine patients (5 with constriction and 4 with effusion) with a prior limited pericardial procedure required formal pericardiectomy. The operative mortality rate for pericardial effusion and constriction was 4.2% and 5.6%, respectively. Follow-up (median follow-up, 56.9 +/- 38.2 months) was obtained on 56 patients (93.3%). Actuarial survival at 1 year, 5 years, and 10 years for all patients was 82.1% +/- 5.1%, 71.7% +/- 6.7%, and 59.8% +/- 12.2%, respectively. A Cox proportional hazards regression analysis was performed using 20 clinical variables. A history of malignancy, previous pericardial procedure, and preoperative New York Heart Association class IV were found to be predictors of poor survival. All patients who underwent operation primarily for effusion with associated pain are alive and have improved functional capacity without steroid use. We conclude that pericardiectomy can be performed with low mortality and can result in good long-term survival and improved functional capacity. Patients who are seen primarily with pain refractory to steroid therapy can be relieved of symptoms with operation.

Actuarial Analysis↗
PubMed1991

Composite graft repair of Marfan aneurysm of the ascending aorta: results in 100 patients.

One hundred consecutive patients with the Marfan syndrome underwent composite graft repair of an ascending aortic aneurysm between September 1976 and June 1989. Twenty-two patients had ascending aortic dissection at the time of composite graft repair; 18 patients also had a mitral valve procedure. There were no hospital deaths among 92 patients undergoing elective repair. One of 8 patients undergoing emergency repair of a ruptured aneurysm died in the operating room. The overall hospital mortality rate was 1%. There have been ten late deaths among the 99 hospital survivors (10.1%). Five deaths occurred among the first 11 patients in this series and five occurred among the last 88 patients (5.7%). Three late deaths resulted from composite graft endocarditis; 3 other patients with endocarditis are alive after aortic root replacement with cryopreserved homografts. Late coronary dehiscence caused death in 1 patient and was successfully repaired in a second. Actuarial survival for the 100 patients was 92.6% at 5 years and 75.8% at 10 years. Currently, composite graft repair of Marfan aneurysms of the ascending aorta can be performed with low hospital and late mortality. Marfan aneurysms with a diameter of 6 cm or greater should be repaired with the Bentall composite graft procedure, even if the patient is asymptomatic.

Adolescent↗
PubMed1990

Surgical standby for percutaneous transluminal coronary angioplasty: a survey of patterns of practice.

To determine patterns of surgical standby for percutaneous transluminal coronary angioplasty (PTCA), a questionnaire was mailed to 196 US institutions in which PTCA and coronary artery bypass grafting (CABG) are performed regularly. Eighty-nine responses (46%) were received and comprise this report. Of responding institutions, the mean number of hospital beds was 615. In 1987, these institutions performed a mean of 337 PTCAs and 558 open-heart surgical procedures. The rate of emergency CABG for PTCA complications (occlusion, dissection, or coronary perforation) was 4.4% +/- 0.3%, whereas the rate of urgent CABG (within 24 hours) for PTCA failure was 3.7 +/- 0.6%. The incidence of emergency CABG for PTCA complications was higher (5.1% +/- 0.6%) among low-volume PTCA centers (less than 250 cases per year) than at high-volume centers (more than 250 cases per year) (3.7% +/- 0.3%; p less than 0.05). The most common pattern of surgical backup was to maintain an open operating room on standby (57/89, 64%), and the second most common pattern was to make the next open operating room available, allowing operating room access within 1 to 3 hours (21/89, 24%). Nearly a third of institutions (26/89, 29%) maintained a flexible backup arrangement according to PTCA risk. Routine pre-PTCA patient evaluation by surgeon and/or anesthesiologist occurred in 38% (34/89). Fees for standby services were charged by 51% of surgical teams (45/89), 39% of anesthesia teams (35/89), and 38% of operating room facilities (34/89).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1990

Routine use of the left internal mammary artery graft in the elderly.

Left internal mammary artery (LIMA) grafts have better long-term patency rates than do saphenous vein grafts and result in improved late survival. The present study was undertaken to assess the results of LIMA grafting in the elderly. From 1980 through 1988, 723 patients 70 years of age or older had isolated coronary artery bypass grafting performed. During the first 5 years, only 11% of the elderly patients received LIMA grafts, whereas 86% having coronary artery bypass grafting since 1985 had LIMA grafts. Since 1986, LIMA use in the elderly has become routine, with 92% of patients receiving internal mammary artery grafts. During the first 5 years, elderly patients had a hospital mortality rate of 9.3%. Since 1985, the hospital mortality rate fell to 5.5%. In addition, the occurrence of major surgical complications was either unchanged or reduced in patients receiving LIMA grafts. Furthermore, late follow-up indicates a significantly improved 4-year survival rate in patients with internal mammary artery grafts compared with those without: 86 +/- 0.02% versus 77 +/- 0.03% (p less than 0.01). Analysis of multiple potential risk factors for early mortality was performed using multiple logistic regression and late survival using the Cox proportional hazards model. Although unmeasured predictor variables may confound retrospective analyses, LIMA grafting appears to be an independent predictor both of improved early and late survival.

Aged↗
PubMed1990

Leukocyte depletion ameliorates free radical-mediated lung injury after cardiopulmonary bypass.

Activated leukocytes and oxygen free radicals have been implicated in the pathogenesis of lung injury associated with cardiopulmonary bypass. To determine whether leukocyte depletion could prevent this injury, we used a dog model simulating routine cardiac operations. Mongrel dogs (11 to 17 kg) were subjected to cardiopulmonary bypass with a bubble oxygenator and cooled to 27 degrees C. After aortic crossclamping and cardioplegic arrest for 90 minutes, control animals (n = 5) were rewarmed and weaned from bypass, and their condition was then stabilized for 90 minutes. Leukocyte-depleted animals (n = 5) had a leukocyte filter incorporated in the bypass circuit. During bypass, circulating leukocyte counts decreased by 60% in control dogs, and by 97% in leukocyte-depleted animals. Free radical generation (estimated by spectrophotometric assay of plasma conjugated dienes) was significantly reduced by leukocyte depletion during and after bypass. Total hemolytic complement activity and the titer of C5 decreased markedly immediately after the onset of bypass in both the control and leukocyte-depleted animals. Pulmonary function after bypass was better preserved in leukocyte-depleted animals. These data suggest that depletion of circulating leukocytes contributes to lung injury during cardiopulmonary bypass and is associated with increased oxygen radical activity, pulmonary edema, and vasoconstriction. Leukocyte depletion substantially reduced the pulmonary injury seen after cardiopulmonary bypass.

Animals↗
PubMed1989

Unique aspects of heart and lung transplantation exhibited in the 'domino-donor' operation.

During the past 2 decades various refinements in heart and lung transplantation procedures have taken place. Improved preservation methods, new immunosuppressive medications, and advances in technical capabilities have allowed innovative procedures to be performed. In May 1987 the first "domino-donor" operation was performed in the United States. A 28-year-old man with cystic fibrosis and end-stage lung disease received the heart and lungs of an anonymous donor after he donated his heart to a 38-year-old man with end-stage ischemic cardiomyopathy. The technical and logistical aspects of this transplantation procedure are described herein. Other unusual features of this case that are discussed include heart-lung transplantation for a patient with cystic fibrosis, the use of cardiopulmonary bypass to allow lung procurement and transplantation across long distances, and the current role of heterotopic cardiac transplantation.

Adult↗
PubMed1989

Exploratory analysis of time-dependent risk for infection, rejection, and death after cardiac transplantation.

Data from 95 heart transplantations performed at The Johns Hopkins Hospital from July 1983 to October 1988 were analyzed to detect patterns of morbidity and mortality. Using nonparametric techniques, hazard functions were determined for all deaths and for deaths due to infection or rejection. The rates of rejection and infection (episodes per patient-month) were determined within each of ten intervals following transplantation. A total of 19 deaths, 281 rejection episodes, and 180 distinct infections were available for analysis during a follow-up of 1 to 62 months. The hazard function for rejection appeared biphasic, with a rapidly decelerating early phase during the first year followed by a constant late phase. The hazard function for infection was triphasic, with a delayed, decelerating early phase, a period of increased risk approximately 2 years after operation, and finally a late constant phase. Both infection and rejection rates (episodes per patient-month) were biphasic, with rapidly decelerating early phases and constant late phases. Multiple regression analysis demonstrated that eventually nonsurviving patients had significantly higher rates of rejection and infection during both the early and late phases compared with survivors. The increased rate of rejection among nonsurvivors was evident throughout follow-up, although no deaths were attributable directly to rejection after the first 8 months. These data suggest that a complex interrelationship between infection and rejection determines late survival after cardiac transplantation and that aggressive treatment of late rejection predisposes toward death from infection.

Actuarial Analysis↗
PubMed1989

Does hypothermic fibrillatory arrest improve myocardial protection during emergency revascularization?

Hypothermic fibrillatory arrest (HFA) was compared with conventional hypothermic cardioplegic arrest (HCA) in a model of acute regional ischemia. In 20 pigs, the left anterior descending coronary artery was occluded for 30 minutes before cardiopulmonary bypass. In the HCA group (n = 10), the heart was arrested with a hyperkalemic cold crystalloid solution, whereas in HFA animals (n = 10), the heart was vented and allowed to fibrillate spontaneously without cross-clamping. Miniature pH probes monitored intramyocardial pH during 45 minutes of arrest (HCA or HFA, both with systemic and topical myocardial cooling) and during two hours of coronary reperfusion. Hypothermic fibrillatory arrest did not ameliorate the acidosis in the ischemic (left anterior descending) region; indeed, after two hours of coronary reperfusion, there was a trend toward more acidosis in the postischemic left anterior descending territory in the HFA group. However, HFA did prevent acidosis in the nonischemic (left circumflex) territory. Infarct size expressed as percent of region at risk was 18.1% +/- 3.2% (mean +/- standard error of the mean) in the HCA animals and 18.8% +/- 4.4% in the HFA animals. These results demonstrate that HFA offers no advantage over HCA in protection of regionally ischemic myocardium in a model with minimal collateral circulation.

Animals↗
PubMed1989

Cardiopulmonary bypass with profound hypothermia. An optimal preservation method for multiorgan procurement.

Numerous techniques have been devised for the harvesting of individual organs during a multiorgan procurement operation. Cardiopulmonary bypass with profound hypothermia (PH) has been employed in successful harvesting of heart-lung, kidney, pancreas, and liver grafts. This report summarizes our experience using CPB-PH for the harvesting of multiple organs from 10 brain-dead donors during the period from July 1983 to January 1988. Organs harvested included 10 heart-lungs, 17 kidneys (3 kidneys were not harvested due to anatomy and elevated creatinine), 1 liver, and 1 pancreas. Mean ischemic time for the distantly procured heart-lung grafts was 281 +/- 10 min. Adequate pulmonary function, as assessed by arterial blood gases, was observed in each heart-lung recipient (mean PO2 was 119 +/- 46 mmHg, 164 +/- 47 mmHg, 130 +/- 30 mmHg, 114 +/- 26 mmHg at immediate post-CPB, 6 hr postop, 24 hr postop, and postextubation, respectively). Mean length of intubation was 34 +/- 8 hr. Mean creatinines of kidney recipients at days 2, 7, and current creatinine were 7.4 +/- 3.6 mg%, 3.6 +/- 2.4 mg%, and 1.6 +/- 0.66 mg%, respectively. Eight kidney recipients (47%) required dialysis, (2 patients required only a single dialysis). Ninety-four percent of the kidney transplant patients are alive, and 88% (15/17) have functioning kidneys. One liver and 1 pancreas were harvested during this time period. Preservation was satisfactory in both the pancreas (Johns Hopkins Hospital) and liver (Dr. Thomas Starzl, personal communication). The technique of CPB-PH has resulted in excellent function of heart-lung grafts. Follow-up of the transplanted kidneys, liver, and pancreas utilizing this technique shows equal or better function compared with standard techniques. This technique offers other advantages in addition to satisfactory multiorgan preservation. Placement of an unstable patient on CPB ensures adequate organ perfusion and allows for a gradual yet uniform cooling of all organ systems. Cooling to a core temperature of 10-15 degrees C requires 30 min, during which time preliminary intraabdominal and mediastinal dissection can be carried out. Following cessation of CPB and subsequent exsanguination, organs can be more easily dissected in a near-bloodless field. This technique does not preclude additional crystalloid organ flushing. Since multiorgan procurement occurs with virtually every donor, this technique may be the optimal method providing excellent preservation, ease of dissection, and better control of hemodynamics during the operation.

Cardiopulmonary Bypass↗