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Biomedical subjects

T Aherne

Publications and source records attributed to T Aherne.

At least 19 recordsLinked to original sources
PubMed2004

How much heparin do we really need to go on pump? A rethink of current practices.

OBJECTIVES: Patients undergoing myocardial revascularisation using extracorporeal circulation require heparin anticoagulation. We aimed to evaluate the effect of reducing heparin dosage on target activated clotting time (ACT) and postoperative blood loss. METHODS: In a prospective randomised trial, 195 patients undergoing isolated primary CABG were randomised into four groups A, B, C, and D receiving an initial heparin dosage of 100, 200, 250 and 300 iu/kg, respectively. Extra incremental heparin (50 iu/kg) was added if required to achieve a target ACT of 480 s before initiating cardiopulmonary bypass. Postoperative blood loss was measured from the time of heparin reversal to drain removal 24h later. RESULTS: Target ACT was achieved in 0, 63, 68.3 and 82.4% of patients in groups A, B, C and D, respectively, after the initial dose of heparin. In group B, of those not achieving target act a single increment of heparin was sufficient to achieve target ACT in further 18.6%. The mean ACT after the initial dose in groups B, C and D was 482.9, 519 and 588 s, respectively (P<0.05). Postoperative blood loss in millilitre per kilogram was directly proportional to preoperative heparin dose. CONCLUSIONS: Patients receiving lower dose of heparin has lower postoperative blood loss. Of those achieving the target ACT, group B was significantly the closest to the target ACT. A starting dose of 200 iu/kg of heparin and if necessary one 50 iu/kg increment achieved target ACT in 81.5% of patients. The added benefit of significant drop in postoperative blood loss is evident.

Aged↗
PubMed2003

A new specifically designed forceps for chest drain insertion.

Insertion of a chest drain can be associated with serious complications. It is recommended that the drain is inserted with blunt dissection through the chest wall but there is no specific instrument to aid this task. We describe a new reusable forceps that has been designed specifically to facilitate the insertion of chest drains.A feasibility study of its use in patients who required a chest drain as part of elective cardiothoracic operations was undertaken. The primary end-point was successful and accurate placement of the drain. The operators also completed a questionnaire rating defined aspects of the procedure. The new instrument was used to insert the chest drain in 30 patients (19 male, 11 female; median age 61.5 years (range 16-81 years)). The drain was inserted successfully without the trocar in all cases and there were no complications. Use of the instrument rated as significantly easier relative to experience of previous techniques in all specified aspects. The new device can be used to insert intercostal chest drains safely and efficiently without using the trocar or any other instrument.

Adolescent↗
PubMed2002

Electrical failure during cardiopulmonary bypass: an evaluation of incidence, causes, management and guidelines for preventative measures.

The incidence of electrical failure during cardiopulmonary bypass (CPB) has been reported to occur in approximately 1 per 1000 cases. While the resultant morbidity and mortality is low, electrical failure is a life-threatening scenario. We report three major electrical failures during CPB in a patient population of 3500 over a 15-year period. These cases involved mains failure and generator shut down, mains failure and generator power surge, and failure of the uninterruptable power supply (UPS), which caused protected sockets to shut down. Protocols for preventative maintenance, necessary equipment, battery backup and guidelines for the successful management of such accidents during CPB are discussed.

Aged↗
PubMed2001

The effects of venous cannulation technique and cardioplegia type on plasma potassium concentration and arterial blood pressure during cardiopulmonary bypass.

The cannulation method and cardioplegia solution used during cardiopulmonary bypass (CPB) may both influence plasma potassium concentrations ([K+]) and mean arterial blood pressure (MAP). Bi-caval or right atrial cannulation methods are routinely used in conjunction with crystalloid or blood cardioplegia. We investigated the influence of cannulation method and cardioplegia solutions on plasma [K+] and MAP during cardiopulmonary bypass. Sixty consecutive patients undergoing elective coronary artery bypass grafting (CABG) using CPB were studied. They were randomly divided into three groups of 20 patients. Patients in Group A underwent bi-caval venous cannulation and received crystalloid cardioplegia. Group B patients underwent right atrial cannulation and received crystalloid cardioplegia. Group C patients underwent right atrial cannulation and received blood cardioplegia. In each case. cardioplegia was administered antegrade via the aortic root. Plasma [K+], MAP. and hemoglobin concentration (Hb) were measured over an 8-min period following cardioplegia administration (pilot studies indicated pressure changes occuring post cardioplegia administration up to this time). The combination of bi-caval cannulation and crystalloid cardioplegia (Group A) was associated with the least increase in plasma [K+] and no decrease in MAP. The maximum [K+] for this Group was 4.2 mmol/L (4.6% increase). The minimum mean pressure was 57 mmHg (13.6% increase). Both right atrial cannulation groups (B and C) showed a large rise in plasma [K+] and a decrease in MAP. Group B maximum [K+] was 5.2 mmol/L (27.5% increase). Group C was also 5.2 mmol/L (26.0% increase). Group C showed the largest pressure decrease, the minimum mean pressure was 45 mmHg (21.3% decrease). The Group B minimum mean pressure was 45 mmHg (8.7% decrease). Our results show that patients undergoing CPB operations who are deemed to be at increased risk of suffering adverse effects from hypotensive episodes may benefit from bicaval cannulation and caval snaring, in preference to right atrial cannulation. Crystalloid cardioplegia may be preferable to blood cardioplegia in these cases to maintain the MAP.

Arteries↗
PubMed1998

Long-term clinical outcome following coronary artery bypass grafting for isolated stenosis of the left anterior descending coronary artery.

AIMS: To detail the clinical and angiographic profile, and long-term outcome in consecutive patients with isolated stenosis of the left anterior descending coronary artery undergoing bypass surgery. METHODS: A retrospective study of all patients (n = 301) (January 1984-December 1990) and undergoing coronary artery bypass grafting for isolated left anterior descending disease, in the Irish Republic, was performed. Survival was compared with that of an exact age- and gender-matched cohort. RESULTS: Mean age was 53 (+/- 9.3) years. There were 238 (79%) males. In 241 (80%) patients an internal thoracic arterial bypass graft was used. Operative mortality was 1.3%. Of the 280 (93%) patients alive (16 cardiac deaths) at 7.1 (+/- 1.9) years, 105 (35%) had angina, 26 (9%) suffered an interval myocardial infarction, and repeat revascularization was required on 29 (10%). Female gender (P = 0.002), pre-operative myocardial infarction (P = 0.02), significant diagonal disease (P = 0.04) and postoperative myocardial infarction (P = 0.0001) were independently associated with survival. Females were more likely to develop congestive cardiac failure (P = 0.01) or postoperative angina (P = 0.03) than their male counterparts. CONCLUSIONS: Survivorship (97%) and event-free survival (96%) at 5 years following coronary artery bypass grafting for isolated left anterior descending coronary artery disease is excellent and equivalent to an age-matched and gender-matched cohort.

Adult↗
PubMed1998

Contemporary developments in the utilization of metal-ceramic restorations: a review.

Numerous porcelain systems and techniques are currently available for utilization in full-coverage anterior crown restorations. Significant improvements have been made in the placement of margins and the reduction of the metal framework in order to enhance the optical effects (e.g., illumination, warmth, and vitality) of these porcelain systems. This article presents several recent developments in the fabrication of metal-ceramic crown restorations, and demonstrates the use of these principles in the aesthetic oral rehabilitation.

Adult↗
PubMed1995

Prostacyclin and thromboxane levels in pleural space fluid during cardiopulmonary bypass.

Prostaglandins exhibit a variety of cardiovascular actions that may affect the hemodynamic recovery of the ischemic myocardium after cardiopulmonary bypass. We have observed a decrease in the mean arterial pressure on autotransfusion of the accumulated pleural cavity fluid during operation. One aim of this study was to determine the concentrations of prostacyclin and thromboxane A2 in the pleural cavity fluid by measuring their stable metabolites, 6-keto-PGF1 alpha and thromboxane B2, respectively, in 8 consecutive patients undergoing myocardial revascularization, and to compare them with the arterial levels. A second aim was to quantify the hemodynamic effect of the pleural cavity fluid during operation. The concentration of 6-keto-PGF1 alpha in the pleural cavity fluid was significantly higher than the arterial concentration (mean, 21.6 +/- 18.2 ng/mL; p < 0.01). The concentration of thromboxane B2 was also raised compared with the arterial concentration (mean, 3.62 +/- 5.96 ng/mL; p < 0.2). The percentage fall in the mean arterial pressure was 29.7% +/- 8.86% (p < 0.02), which was transient and lasted 1 to 3.5 minutes. The hemoglobin concentration, potassium level, and pH were also measured. This study shows that the pleural cavity fluid during cardiac operations contains significant amounts of endogenous prostacyclin. Considering the potential benefit of prostacyclin on the recovering myocardium, we believe that this fluid should be transfused as a volume replacement, keeping in mind the transient phase of hemodynamic instability.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Atrial myxoma: national incidence, diagnosis and surgical management.

Despite being the most common benign intracardiac tumour with an excellent prognosis after surgical excision the incidence of atrial myxoma (except at autopsy) is unknown. We reviewed all patients admitted to the National Cardiac Surgery Unit (n = 26) with an atrial myxoma over a fifteen year period (1977-1991) to compile national incidence data and assess pre-operative diagnosis, management, surgical technique, and outcome. Preoperative symptoms were: congestive cardiac failure (12 patients), embolism (8 patients), constitutional (3 patients), asymptomatic (2 patients) and tachyarrhythmia (1 patient). The diagnosis was confirmed by 2D echocardiography alone in thirteen patients and by a combination of echocardiography and angiography in thirteen patients. At operation the site of the tumour was left atrial in 24 patients and bi-atrial in two patients. All cases were confirmed by histology. All patients made a good post-operative recovery, although one patient survived a pulmonary embolus and one patient developed a deep venous thrombosis. There has been one late death (five months after surgery) from a cerebrovascular accident. Serial echocardiography has revealed one recurrence to date (8 years after surgery). The surgical incidence of these tumours in the Republic of Ireland over the study period was 0.5 atrial myxomas/million population/year. Although rare atrial myxomas are the most important cardiac tumours to diagnose as the results from surgery are excellent.

Adolescent↗
PubMed1991

Mediastinoscopy as a predictor of resectability in patients with bronchogenic carcinoma.

Eighty consecutive mediastinoscopies, performed for assessment of patients with bronchogenic carcinoma, were reviewed with regard to accuracy and complications. Thirty patients had mediastinal lymph node metastases: 26 were considered inoperable and thus saved non-therapeutic thoracotomy, 4 were considered operable of whom 3 had a curative resection, and one was inoperable at thoracotomy. Of 50 patients with negative mediastinal nodes 43 had thoracotomy; 42 were resectable and one was unresectable. Seven did not have thoracotomy because of other contraindications. In total of 47 patients undergoing thoracotomy on the basis of mediastinoscopy, 45 were resectable, giving mediastinoscopy a positive predictive value for resectability of 95.7%. There was no mortality and two superficial wound infections occurred giving a morbidity of 2.5%. Mediastinoscopy is a safe, reliable and accurate predictor or resectability in patients with bronchogenic carcinoma and continues to have a major role in the management of these patients.

Aged↗
PubMed1990

Repeated echocardiography: essential in the management of Staphylococcus aureus endocarditis.

Staphylococcus aureus endocarditis in a previously healthy 25 year old man is described. Repeated echocardiography recorded rapid progression of aortic root and interventricular septal involvement and, even though the patient was clinically stable, early surgery was advised with a satisfactory outcome. This case report clearly demonstrates the vital role of repeated cross-sectional echocardiography in the management of such cases.

Adult↗
PubMed1989

Low potassium cardioplegia: its effect on the incidence of complete heart block following cardiac surgery.

To investigate whether the concentration of potassium ion in cardioplegic solution was related to the incidence of complete heart block in patients undergoing myocardial revascularisation 163 consecutive cases were studied. Cardiac arrest was with St. Thomas' hospital cardioplegic solution in all patients. Ongoing myocardial protection was provided with St. Thomas' hospital solution (potassium concentration 20 mmol/l) in 56 patients (group A) and with Ringer's injection (potassium concentration 4 mmol/l) in 107 patients (group B). These two groups were studied sequentially. The incidence of complete heart block was higher in group A than in group B. Following aortic unclamping, 27 per cent of patients in group A compared to 14 per cent in group B exhibited the phenomenon (p less than 0.05). At the time of weaning from cardiopulmonary bypass the incidence was 20 per cent in group A compared to 10 per cent in group B (p less than 0.1). No differences were demonstrated between the two groups in terms of myocardial recovery, morbidity or mortality.

Cardioplegic Solutions↗
PubMed1986

Right-sided cardiac transplantation: importance of functional valves.

An original surgical procedure had been developed entailing the implantation of a right-sided heterotrophic cardiac graft in 14 dogs. The benchwork preparation included creation of both atrial and ventricular septal defects which allowed transplantation with the avoidance of extracorporeal circulation and the utilization of all transplanted myocardium and parts. The structure and function of this graft were sequentially evaluated using rapid cine-computed tomograms which permitted assessment of forward graft flow, ventricular wall contraction, and diastolic thickness for both the native and grafted hearts. These parameters were followed during the early (E) (less than 3 days), intermediate (I) (4-21 days), and late (L) (greater than 21 days) postoperative periods. Forward flow (E: 3.0, I: 1.5, L: 2.6) through the transplant was maintained by the competence of the implanted valves despite a progressive decrease in the contraction (E: 3.0, I: 1.3, L: 1.0) and associated decrease in the wall thickness (E: 3.0, I: 2.6, L: 2.4). These findings were consistent with severe cardiac graft rejection without immunosuppression. In summary, long-term structural and functional forward flow of this configurated right-sided transplantation had been maintained by the competent valves on both sides of the graft despite severe rejection without immunosuppression as documented by rapid cine-computed tomograms.

Animals↗