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Biomedical subjects

A R Kerr

Publications and source records attributed to A R Kerr.

At least 37 records · Page 2Linked to original sources
PubMed1994

Waiting lists for coronary artery surgery: can they be better organised?

AIM: To determine whether a numerical ranking system can provide an equitable basis for prioritising patients awaiting coronary artery bypass grafting. METHODS: A review of the current coronary surgery waiting list was undertaken using a newly developed scoring system. The factors included in the score were age, symptoms, results of exercise testing, coronary anatomy, employment status and perceived surgical risk. This score was compared with a Canadian consensus system. Rankings were then compared with the clinical priorities given by clinicians when the patients were placed on the waiting list. RESULTS: There was excellent correlation between the two priority ranking systems using only those items included in the Canadian system (r = 0.9179). However, correlation between the Canadian system and the full Green Lane Hospital (GLH) scoring system was weaker (r = 0.6869). The Canadian system assigned higher surgical priorities than Auckland clinicians. Comparison between the GLH system and clinical priority gradings (O, urgent out of hospital), (A) and (B) showed considerable scatter. Waiting times for these three categories considered acceptable by the Canadian consensus group were two to six weeks for priority (O), six weeks to three months for priority (A) and three to six months for priority (B). The mean times on the waiting list for the 260 patients still awaiting surgery at GLH were two months for (O), 11 months for (A) and 22 months for (B). CONCLUSIONS: The Canadian and expanded GLH ranking systems are no more than aids to establishing priorities. They cannot replace clinical judgement because the importance of individual scoring items is heavily influenced by the ranking of other items. Waiting times for surgery are now grossly excessive despite the use of criteria for entry to the waiting list which are very conservative by international standards. There is no equitable or clinically acceptable way to modify priorities to reduce waiting times, and institution of a booking system is impractical.

Aged↗
PubMed1994

End-systolic volume and long-term survival after coronary artery bypass graft surgery in patients with impaired left ventricular function.

BACKGROUND: Left ventricular function is the main predictor of long-term survival in patients with coronary artery disease. In patients with impaired left ventricular function after myocardial infarction, end-systolic volume is a better predictor than the global ejection fraction. We analyzed long-term follow-up of patients with impaired left ventricular function undergoing coronary artery bypass graft surgery to evaluate preoperative predictors of survival. METHODS AND RESULTS: Consecutive patients with ejection fractions < or = 40% (n = 193) who had undergone surgical revascularization were followed to assess the predictive value of preoperative baseline characteristics and catheterization findings for long-term survival. Patients were followed for 133 +/- 30.7 months. At the time of surgery, patient age was 56 +/- 7.9 years and 169 patients (87.6%) had a history of previous myocardial infarction. Thirty-one patients (16%) were female. The ejection fraction was 32 +/- 7%, and the end-systolic volume was 147.4 +/- 52.6 mL. One hundred sixty-four patients (84.9%) had three-vessel disease, and 44 (22.8%) had a left main stenosis with > 50% diameter loss. Follow-up was complete in 99%. Fourteen patients died (7.3%) within the first 30 days after surgery. Twelve-month actuarial survival was 86%, 4-year survival was 80%, and 10-year survival was 40%. Predictors of poor long-term survival on multivariate analysis were end-systolic volume index (chi 2 = 14.02, P = .002), number of previous myocardial infarctions (chi 2 = 6.47, P = .001), preoperative stenosis score (chi 2 = 4.97, P = .02), and age at the time of surgery (chi 2 = 4.45, P = .03). CONCLUSIONS: End-systolic volume index is the major predictor of survival after coronary artery bypass graft surgery in patients with impaired left ventricular function. Strategies to prevent ventricular dilatation, such as angiotensin-converting enzyme inhibitors, may improve the long-term outcome in these patients.

Adult↗
PubMed1993

Coronary artery surgery in the elderly: long-term follow-up.

BACKGROUND: There has been controversy concerning the indications for coronary artery surgery in the elderly, particularly in countries where health resources are restricted. AIMS: To assess the results of coronary artery bypass grafting (CABG) in a large group of elderly subjects with regard to initial risks and long term follow-up. METHODS: Ninety-six consecutive patients aged 70 years or older underwent isolated CABG between January 1981 and December 1985. Long term follow-up was obtained in 94 (98%). RESULTS: The mean age was 71.6 years (70-78) and mean duration of follow-up 73 months. Seventy (73%) were male. In 80 cases the myocardial score was > 10. In 22 of 90 who had left ventricular angiography the ejection fraction was < 50%. Hospital survival was 96% and the five year survival 77%. It was not influenced by gender, myocardial score, ejection fraction or age at the time of operation. The status of survivors was reviewed in 1991. Of the 55 long term survivors 35 (64%) were free of angina. Eight (15%) and ten (18%) were in the Canadian Cardiovascular Society Angina classes 1 and 2 respectively. Seventeen patients (31%) had symptoms of heart failure with 14 (25%) in NYHA class 2 and 3 (5%) in class 3. Eight patients (15%) had survived a cerebrovascular event during follow-up. There were 35 late deaths (37%). Sixteen of these were cardiac, 18 due to other causes and one unknown.

Aged↗
PubMed1993

Aortic valve replacement in the elderly.

Aortic valve replacement is an established mode of therapy that enhances and prolongs life in patients with significant aortic valve disease. This is true for the elderly, but with a higher reported mortality and morbidity than in younger patients. One hundred and eighty-three elderly patients aged 70 years and over were considered suitable candidates for isolated aortic valve replacement (n = 97) or aortic valve replacement combined with coronary artery bypass surgery (n = 86) in the decade 1980-89. The mean age at surgery was 73.2 years (70-80). The hospital mortality and morbidity of this group were compared to 340 consecutive patients aged 60-69 who underwent similar surgery over the same period. There was no significant difference in hospital mortality: 4.4% for elderly patients and 4.1% for those aged 60-69. Measures of hospital morbidity were similar except for the perioperative stroke rate, which was 4.4% in the elderly patients and 1.5% in the younger group (p < 0.05). Detailed long term follow up was obtained in 75 of the 76 elderly patients who underwent aortic valve replacement or aortic valve replacement combined with coronary artery bypass surgery in the first five year period. Hospital survival was 99% (one hospital death). The overall five year actuarial survival was 81% and greater than the age and sexmatched general population (73%). Of the 44 patients alive at the time of review, 35 (80%) were free of angina and 32 (73%) had no significant symptoms of heart failure. Additionally, these patients were questioned about their quality of life.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1992

The role of dipyridamole in addition to low dose aspirin in the prevention of occlusion of coronary artery bypass grafts.

One hundred and one subjects were randomised to receive either aspirin 100 mg or aspirin 100 mg + dipyridamole 300 mg daily before undergoing coronary bypass surgery. The drugs were commenced at least 36 hours before operation and patients were followed for one year. There were three perioperative deaths and 37 withdrawals, of which 14 were drug related (aspirin four, aspirin + dipyridamole ten). Cineangiocardiograms at nine weeks and one year showed vein graft patency rates of 93% and 87% for subjects treated with aspirin alone; and 90% and 89% in those who received aspirin+dipyridamole. During the follow-up period 14% of 232 coronary lesions in the aspirin treated group advanced by more than two grades compared with 15% of 315 lesions in the aspirin+dipyridamole group. The study did not establish superiority of one regimen over another in terms of graft patency or progress of lesions in native vessels. However, low dose aspirin was better tolerated than combination therapy.

Aged↗
PubMed1991

Fatal cerebral haemorrhage after tiger snake (Notechis scutatus) envenomation.

OBJECTIVE: This case report illustrates the threat to life posed by tiger snake venom-induced coagulopathy, the importance of first-aid, precautions with antivenom administration, the dose of antivenom and the necessity to monitor the coagulation status. CASE SUMMARY: An 11-year-old child was envenomated several times by a tiger snake (Notechis scutatus). Despite administration of three ampoules (9000 units) of tiger snake antivenom, fatal cerebral haemorrhage occurred. Inadequate first-aid had been applied. The bite site was covered with a loose bandage instead of a pressure-immobilisation bandage. In hospital, facilities to monitor coagulation status were unavailable. CONCLUSIONS: More public education is required in first-aid management of snake envenomation. Frequent monitoring of coagulation status is necessary to optimise antivenom and coagulation factor therapy.

Blood Coagulation↗
PubMed1991

Progress of patients with pulmonary atresia after systemic to pulmonary arterial shunts.

Between February 1980 and June 1987, 42 shunts were placed in 39 infants with pulmonary atresia: 33 were modified Blalock-Taussig shunts with polytetrafluoroethylene (PTFE) and 9 were classic Blalock-Taussig shunts. There were four hospital deaths not related to the shunts. The remaining 35 patients were followed up for 1.6 months to 6.3 years (mean, 24.7 +/- 18 months). Repeat cineangiocardiographic studies revealed stenosis or distortion of the pulmonary arteries related to the site of the shunt in 11/22 patients (50%) with PTFE shunts and in 1/6 (17%) with classic Blalock-Taussig shunts; the stenosis was severe in only 1 patient. Mean increase in the pulmonary arterial index in the group with classic Blalock-Taussig shunts was 117 +/- 52 mm2/m2 (not significant) and in the group with PTFE shunts, 158 +/- 21 mm2/m2 (p less than 0.001). Late shunt occlusion occurred in 1 patient 23 months postoperatively. Thereafter, shunt patency rate remained at 94% +/- 6%. At the end of 1 year 81% +/- 7% of patients were judged to have adequate palliation, but between 2 and 3 years, only 60% +/- 10%. Univariate analysis showed that after 2 years the ranking order for successful palliation was classic Blalock-Taussig, 5-mm PTFE, and 4-mm PTFE shunts, but differences did not achieve statistical significance.

Abnormalities, Multiple↗
PubMed1989

Assessment and follow-up of patients with ventricular septal defect and elevated pulmonary vascular resistance.

Cardiac catheterization was undertaken in 87 patients (for a total of 89 studies) with ventricular septal defects, including 58 patients with moderate or severe elevation of pulmonary arteriolar resistance. When resting resistance was less than or equal to 7.9 U . m2, it always decreased with isoproterenol and no postoperative problems were experienced with pulmonary vascular obstructive disease. In 36 patients resting resistance measured greater than or equal to 8 U . m2. In 17 of these patients it decreased to less than 7 U . m2 with isoproterenol. Fifteen patients were operated on and postoperative problems with pulmonary vascular disease were experienced only in the single patient whose repair broke down. Surgery was undertaken in 4 of 19 patients in whom resistance did not decrease to less than 7 U . m2 with isoproterenol and advanced pulmonary vascular disease was evident in the 3 patients with follow-up observation. Correlation between measured resistance and other hemodynamic parameters was only fair. A pulmonary to systemic resistance ratio greater than or equal to 0.75 always indicated high absolute resistance but resistance ratios less than 0.75 were found quite frequently in the group with limited response to isoproterenol. These data argue that a reliable estimate of resistance, less than 7 U . m2, with a vasodilator predicts a good postoperative response regardless of measurements at rest or other hemodynamic parameters. Although observations on postoperative progress of patients with resistance greater than 7 U . m2 with a vasodilator are limited, a good postoperative course is unlikely unless resistance can be lowered to a level close to 7 U . m2.

Adult↗
PubMed1988

Early and late results of re-operation for coronary artery disease: a 13-year experience.

A second coronary artery bypass grafting procedure was performed for recurrent angina in 119 patients between 1970 and mid-1983. Angiographic findings were assessed and computerized using the Brandt myocardial scoring system. The myocardial score was similar prior to the first and second operations. Graft failure was the most common indication for re-operation, either alone (48%) or in combination with progression of coronary artery disease (29%) or incomplete revascularization (10%). Progression of coronary artery disease alone was an indication in 9% and previous incomplete revascularization alone in 4%. The completeness of revascularization at the end of operation was analysed using a new index, the myocardial score/graft coverage rate. This showed that revascularization was less complete at the second operation than at the first (P less than 0.0001). The hospital mortality at re-operation was 2.5% and the peri-operative myocardial infarction rate was 9.2%. The follow-up period was 54 months (range 10-160 months). Actuarial survival was 94% at 5 years and 74% at 10 years. The average onset of recurrent angina was earlier after the second operation than after the first (P = 0.001). Using a cumulative actuarial curve, survival at 8 years was 85%, a further 6% of patients had undergone a third or fourth operation, and a further 25% were in NYHA Classes III or IV. Therefore 54% achieved a good or excellent result. It was concluded that re-operation is a worthwhile procedure.

Angina Pectoris↗
PubMed1986

Multivariate analysis of the long-term results of coronary artery bypass grafting performed during 1976 and 1977.

The results of 492 consecutive coronary artery bypass grafting operations performed for angina in the 2-year period from 1976 to 1977 were evaluated 77 months after surgery. Follow-up was complete in 99%. In 80% of patients angina severity was New York Heart Association functional classes III or IV. An ejection fraction of less than 50% and left ventricular end-diastolic pressure of more than 15 mm Hg were each present in one-third of patients. Thirteen patients (2.6%) died in hospital and 70 (14%) died later during the follow-up period. Twenty-six reoperations were performed for recurrent angina (5.3%). Angina was initially relieved by operation in 97% of patients, but only 57% were alive and free of angina 6 years after their operation. Despite this, 91% of patients at last follow-up were in functional class I or II and 94% thought their symptoms were better than preoperatively. The mean postoperative time of onset of angina, estimated independently by family physicians and patients, was 33 months. The significant preoperative predictors of late death were a low left ventricular ejection fraction, previous myocardial infarction, prior cardiac surgery, increased cardiothoracic ratio and the number of coronary arteries with significant narrowing.

Adult↗
PubMed1985

Prosthetic repair of coarctation of the aorta with particular reference to Dacron onlay patch grafts and late aneurysm formation.

Prosthetic material was used in the repair of coarctation of the aorta in 72 patients followed for 8 months to 24 years after operation. False aneurysms occurred late postoperatively in 1 of 17 instances when a tube graft was used to replace the resected aorta and in 1 of 2 patients when the graft bypassed the obstructed area. A Dacron onlay patch graft (DOPG) was used in 52 patients as the primary method of repair, to revise a previous repair or as an adjunct to another procedure at the time of initial operation. True or false late aneurysm occurred between 6 and 18 years postoperatively in 5 of the 38 patients in whom a DOPG was used for primary repair of the coarctation or to revise an earlier repair, an actuarial incidence of 38% at 14 years. Diagnosis of aneurysm formation late postoperatively depends on awareness of this complication and careful assessment of lateral as well as posteroanterior chest radiographs. DOPG should be avoided whenever possible.

Actuarial Analysis↗
PubMed1985

Arrhythmia prophylaxis after aorta-coronary bypass. The effect of minidose propranolol.

After aorta-coronary bypass grafting, 164 consecutive patients were randomized to receive propranolol 5 mg every 6 hours orally (n = 82) or to serve as control subjects (n = 82). All patients were receiving beta blockers preoperatively. There were no significant differences between the two groups. The incidence of sustained supraventricular (nonsinus) tachyarrhythmias was 23% in the control group and 9.8% in the treated group (p = 0.02). The incidence of ventricular arrhythmias was 15% in the control group and 2.4% in the treated group (p = 0.005). The overall difference in clinically important arrhythmias was 38% in the control group and 12.2% in the treated group (p = 0.0002). We conclude that low-dose oral propranolol in patients who were receiving beta blockers preoperatively is effective in reducing the incidence of clinically important arrhythmias occurring after aorta-coronary bypass grafting.

Aged↗
PubMed1983

Serum myoglobin concentration as an index of myocardial damage after cardiac surgery.

We assessed serum myoglobin concentration as an index of myocardial damage after cardiothoracic surgery in a dog model and man. Experimentally, we compared 12 dogs subject to left thoracotomy either with or without coronary artery ligation to cause an infarct. Serial blood sampling for 24 hours after surgery showed that the times taken for the myoglobin peak concentrations to appear distinguished the two groups without overlap. These times were 2.4 +/- 0.4 hours after surgery without ligation compared with 9.8 +/- 0.8 hours in the ligated group (P less than 0.001). Clinically, serial sampling was performed over 48 hours in 20 patients having undergone cardiac surgery involving cardiopulmonary bypass. A further 80 patients were investigated for 12 hours. Myoglobin was compared with the activities of creatine kinase, 2-hydroxybutyrate dehydrogenase and glutamate-oxaloacetate transaminase in relation to electrocardiographic criteria of myocardial damage. A myoglobin peak greater than 800 micrograms/1 appearing later than 6 hours after starting bypass was found in those patients suffering myocardial damage. The appearance times and activities of the enzymes tested were widely scattered and difficult to interpret. We conclude that blood samples taken at approximately 3 and 6 hours after starting bypass should suffice to characterise both peak myoglobin and its time of appearance which together form a sensitive index of myocardial damage. However, this conclusion is limited by the low incidence of myocardial damage (3%) in this group of patients.

Animals↗
PubMed1982

Late follow-up of the Braunwald-Cutter valve.

A retrospective review has been made of 234 patients who received 239 Braunwald-Cutter valves (109 aortic, 130 mitral). For the aortic valve, the thromboembolic rate was very high (10.3 per 100 patient-years). This was associated with severe strut cloth wear in 94.5% of valves and with long strands of fibrin attached to the worn cloth in 58% of valves studied at reoperation or postmortem examination. The aortic poppet showed a mean decrease in volume of 4%, and poppet escape was recognized in 4 patients. The actuarial incidence of poppet escape was less than that predicted in earlier reports. There was a 4% incidence of stenosis of the valve. The hospital mortality associated with removal of the aortic Braunwald-Cutter valve and replacement with another device was 4%. Performance of the mitral Braunwald-Cutter valve appears satisfactory to date (mean follow-up, 42 months). Its electric removal is not recommended.

Actuarial Analysis↗
PubMed1981

Infective endocarditis: a lethal disease.

One-hundred-and-eighty-nine episodes of infective Endocarditis were seen in 177 patients in the Green Lane Cardiology Unit over a 18-year period. Hospital survival was 79% and 13-year actuarial survival was 47%. A number of factors including the underlying cardiac lesion, infecting organism, clinical features and surgical intervention were related to outcome. No patient with extreme heart failure survived without operation. Hospital survival in patients with severe heart failure was 69% (9/13 patients) where surgery was carried out before completion of antibiotic treatment, and 40% (6/15 patients) where the antibiotic course was completed. Survival was 53% in patients who still had a fever after one week of antibiotic treatment and 96% if the temperature was normal. In 61% of patients with a fever at one week, extended infected pannus was present compared with 6--10% where the temperature was normal. In patients undergoing operation before completion of antibiotics, the surgical mortality was higher but neither the incidence of recurrence of endocarditis nor the need for re-operation was increased. We believe that better results will be achieved with a policy of surgical intervention when signs of infection and heart failure have not settled within one week of treatment.

Actuarial Analysis↗
PubMed1981

Coronary surgery after recurrent myocardial infarction: progress of a trial comparing surgical with nonsurgical management for asymptomatic patients with advanced coronary disease.

A randomized trial of surgical vs nonsurgical management was carried out in men 60 years of age or younger who had recovered from a recurrent myocardial infarction. Of 205 patients considered, 100 had few or no symptoms and had coronary vessels favorable for bypass grafting; these patients fulfilled the trial conditions and were randomized (50 surgical and 50 nonsurgical). In 41 patients (elective nonsurgical group), randomization was not considered justifiable because of relatively unfavorable coronary anatomy or severe left ventricular dysfunction. Nineteen patients had elective surgery because of disabling angina despite full medical treatment or because of significant left main coronary stenosis. In 45 patients, coronary angiography was not undertaken because of medical contraindications or reluctance of the patient to enter the study. Actuarial survival curves (mean follow-up 4.5 years) show an annual mortality rate of 3-4% per year for all investigated patients, and no advantage for the randomized surgical over the randomized nonsurgical group. The results suggest that in the absence of disabling angina or left main coronary artery stenosis, coronary artery surgery need not be advised for survivors of recurrent infarctions who have severe coronary artery disease. Moreover, the prognosis for the group of patients not treated surgically appears to be better than has been previously described.

Adult↗
PubMed1980

Mitral valve vegetations in bacterial endocarditis resembling left atrial myxoma.

A patient with Staphylococcus aureus endocarditis is reported whose echocardiogram closely resembled that found in left atrial myxoma. Because of severe mitral incompetence, the valve was replaced using cardiopulmonary bypass and at operation a large 3 cm friable vegetation was found attached to the posterior leaflet of the mitral valve. Histological examination showed changes typical of bacterial endocarditis with no evidence of myxoma.

Aged↗