Death of a neonatal lamb due to Clostridium perfringens type B in New Zealand.

Case history and clinical findings: A flock of 20 sheep was kept within three paddocks on a single property. None of the animals in the flock had been vaccinated against any disease for at least three years. Abdominal bloating and haemorrhagic diarrhoea were observed in Lamb 1 at 24 hours-of-age. The lamb subsequently died within an hour of the onset of clinical signs. Lamb 2 was 3-days-old when observed to be recumbent with opisthotonus. The lamb was treated with dextrose, vitamins B1 and B12, and penicillin G, but died 4 hours later.Pathological findings: Examination of Lamb 1 revealed markedly increased gas within the peritoneum and within dilated loops of intestine. The intestines were dark red and contained large quantities of haemorrhagic fluid. Histology of the intestines revealed peracute mucosal necrosis with minimal accompanying inflammation. The intestinal lumen contained cell debris, haemorrhage, and myriad large Gram-positive bacilli. The intestines of Lamb 2 did not appear bloated or reddened. However, multiple fibrin clots were visible within the pericardial sac. Histopathological examination revealed small foci of necrosis within the mucosa of the distal intestine. The necrotic foci were often associated with large numbers of large Gram-positive bacilli.Immunohistochemsitry and molecular biology: Intestinal samples from Lamb 1 were processed for Clostridium perfringens immunohistochemistry, which revealed large numbers of intralesional, positively immunostained rods. Fragments corresponding to the expected sizes for genes encoding alpha, beta, and epsilon C. perfringens typing toxins were amplified by PCR from DNA extracted from formalin-fixed sections of intestine.Diagnosis: Lamb dysentery due to C. perfringens type B.Clinical relevance: C. perfringens bacteria have a worldwide distribution, but disease due to C. perfringens type B has only been diagnosed in a small number of countries and has never been reported in New Zealand or Australia. C. perfringens type B produce both beta toxin and epsilon toxins, therefore both haemorrhagic enteritis and systemic vascular damage can develop. As many animals are exposed to C. perfringens without developing disease, there must be additional unknown factors that resulted in disease in these particular sheep. Vaccines that specifically protect against C. perfringens type B are available and may be recommended for use in smaller non-commercial flocks, as in the present case.

Cryoablation of the accessory pathway in Wolff-Parkinson-White syndrome: initial results and long term follow up.

Cryoablation of the accessory pathway was used in the management of 20 patients with pre-excitation syndromes. All patients had presented with paroxysmal atrioventricular reentrant tachycardia; in addition, six had experienced atrial fibrillation. In 16 patients pre-excitation was overt and in four the accessory pathway was concealed. Intraoperative epicardial and endocardial mapping showed 10 left free wall pathways, seven septal pathways, and four right free wall pathways. One patient had two right free wall accessory pathways. There was one postoperative death (from a ruptured cerebral haemangioma) and one patient had transient hemiparesis. There was early recurrence of arrhythmia or pre-excitation in six patients and five of these were among the first ten in the series. Four of the six underwent successful reoperation; 17 patients remain symptom free of all antiarrhythmic treatment. Two patients did not undergo reoperation--one became symptom free on drugs that had previously been ineffective and the other received an antitachycardia pacemaker. The mean period of follow up was six years. Accessory pathway function was not restored and atrioventricular nodal function was preserved in all patients, demonstrating the feasibility of this technique in the long term management of patients with the pre-excitation syndrome.

Operation for ascending aortic aneurysm and aortic regurgitation--pathological influence on survival.

The author briefly reviews the early operations of treatment of aortic aneurysm and aortic regurgitation leading to his description, in 1968, of the first composite graft replacement of the ascending aorta and aortic valve, with anastomosis of the coronary arteries into the graft. The original operation is described with reference to modifications suggested by a number of authors throughout the last 20 years. Methods of achieving coronary artery continuity by Carrel patch and pull-through by saphenous vein interposition and by synthetic graft techniques are discussed. While any of these methods may be needed in individual cases the preference of the author remains for simplicity. The arguments for and against excision of the aneurysmal sac are considered in relation to the control of haemorrhage. The early and medium term results of operation are good but in comparing results world-wide a lack of uniform diagnostic criteria is apparent. The full clinical Marfan syndrome presents little difficulty but the status of "annuloaortic ectasia", Erdheim's medionecrosis, "cystic medial necrosis" and many other pathological descriptions are not defined: "forme fruste" of Marfan's disease has been used for any of the above. Interpretation of surgical results remains difficult and often impossible in the absence of clear definitions. Recent work on elastic tissue and on the chemistry of collagen together with the hope of identification of the genetic background now offers real hope of clearer understanding.

Mycotic aneurysm of the pulmonary artery. Direct surgical approach with preservation of lung tissue.

A solitary mycotic aneurysm of the right apical lower segmental pulmonary artery developed in an 8 year old child with infective endocarditis, ventricular septal defect and pulmonary hypertension. Surgical treatment was undertaken to prevent rupture and achieved by direct ligation of the feeding vessel and endoaneurysmorrhaphy with preservation of all lung tissue. Successful surgical treatment has been described in eight previous cases of mycotic pulmonary artery aneurysm though in only one adult patient has lung resection been avoided.

Ten-year clinical evaluation of isolated mitral valve and double-valve replacement with the Starr-Edwards prostheses.

From 1974 through 1983, 689 hospital survivors of Starr-Edwards (SE) valve replacement were identified; 279 (40.4%) patients with complete follow-up had an isolated mitral valve (SE model 6120 or 6400) replacement: 60.6% of these patients were women, 33.4% were in sinus rhythm, 32.3% had predominantly mitral stenosis, and 23.6% had predominantly regurgitation. Forty-six (6.7%) patients had mitral and aortic valve (SE model 1260 or 2400) replacement, 60.9% were women, and 13% were in sinus rhythm. To determine the long-term outcome of these SE valve prostheses, 325 (97.8%) patients were observed for up to 10 years. Total 10-year mortality was 40 patients (2.54% patients/yr) in the mitral group, of which 26 deaths (9.3%) were cardiac in origin; 8 deaths (2.8%) were directly valve related. Eight patients died (3.47% patients/yr) in the double-valve group, of which 5 deaths (10.8%) had a cardiac cause; 2 deaths (4.3%) were directly valve related. Primary valve failure was never proved. Actuarial estimates of survival at 10 years were 82 +/- 2.6% for the mitral valve group and 81 +/- 6% for the double-valve group. Actuarial estimates of freedom from valve-related morbidity were 87 +/- 2% for the mitral valve group and 59 +/- 7% for the double-valve group. Actuarial estimates of freedom from thromboembolism were 93 +/- 2% for the mitral valve group and 70 +/- 7% for the double-valve group. This prosthesis-based assessment has shown satisfactory long-term performance characteristics of the SE mitral models 6120 and 6400 without any recorded episodes of mechanical valve dysfunctions.

Usefulness of the phenomenon of histofluorescence in the identification of early myocardial necrosis.

To evaluate the histological phenomenon of fluorescence of necrotic myocardium in ultraviolet light a prospective study of fatal myocardial infarction with accurate clinical and biochemical correlation was made. To test the morphological characteristics and specificity of the technique experimental infarctions were induced surgically in sheep and pigs and acute ischaemia and infarction induced by catheter in intact dogs. Fluorescence was visible within five minutes of the injury in routinely stained sections and persisted for as long as cellular debris was identifiable. It was independent of autolysis, optimal fixation, prolonged storage, and special stains. Although the fluorescence was associated with hypereosinophilia in stained sections, necrotic myocardium also fluoresced in unstained ones, demonstrating primary or autofluorescence. Fluorescence microscopy is a useful adjunct to the histological identification of early myocardial necrosis and of scattered or focal necrosis especially in the absence of myocardial infarction.

The longevity of sterilized aortic valve homografts 1966-1972.

Between 1966 and 1972 seventy-two adult patients underwent aortic valve replacement with unstented aortic valve homografts prepared by chemical beta-propiolactone sterilization and storage. There were 5 hospital deaths and 6 foreign patients are lost to follow-up. Of the remaining 61, there have been 7 late deaths. Thirty-one patients have needed re-operation and 6 of them died. To date, 13 patients still have their homografts--none take anticoagulants and endocarditis has not occurred. The technique for valve preparation is not currently used anywhere, but the results, especially with respect to freedom from endocarditis and from calcification compare most favourably with current methods. The relative freedom from calcification suggests that it may still have relevance to the problems of aortic and pulmonary valve replacement in children.

Determinants of work capability and employment after coronary artery surgery.

In 120 patients subjected to coronary artery surgery we have investigated employment status and work capability in relation to age, pre-operative ventricular function and extent of coronary artery disease, peri-operative infarction and post-operative angina. The patients were followed up for 6 to 23 months (mean 10 months). Fifty-three out of 74 patients (72%) employed before the onset of angina, returned to work after operation. Return to work was more likely in patients working immediately prior to surgery and in patients less than 45 years old (P less than 0.05). Sixty patients (50%) reported a return to normal work capability, the most striking changes occurring in those less than 45 years old (P less than 0.02). Pre-operative left ventricular (LV) function and extent of coronary disease and mode of employment did not correlate with post-operative employment status but normal LV function was related to improvement in work capability (P less than 0.02). Return to work after coronary bypass surgery is mainly due to angina relief but is also related to age and pre-operative work status.

Ten year follow up of models 1260 and 2400 Starr-Edwards isolated aortic valve replacement.

In our experience the structural durability of the S-E models 1260 and 2400 aortic prostheses is excellent, with no episodes of mechanical valve failure recorded over a 10 year period. Long term performance characteristics compare favourably with other published series and other prostheses, with a specifically low incidence of thromboembolism recorded. Such data will provide a useful comparison against newer prostheses in the search for the ideal cardiac valve substitute.

Surgical treatment of infective endocarditis with special reference to prosthetic valve endocarditis.

Patients with native valve endocarditis treated surgically between 1968 and 1978 (n = 15) and all patients presenting with prosthetic valve endocarditis during this period (n = 21) were followed up for at least four years. Five of the patients with native valve endocarditis required urgent early surgical intervention, of whom two died. The remaining 10 underwent valve replacement after a course of antibiotic treatment: all survived, though one required further valve replacement. The 21 patients with prosthetic valve endocarditis suffered 25 attacks. Nine were cured by medical treatment alone; two died before surgical intervention was possible; 11 required valve replacement, of whom three died; and two required valve replacement after a course of antibiotic treatment. The incidence of early prosthetic valve endocarditis--that occurring within two months of operation--was 0.67%, but that of late prosthetic valve endocarditis could not be determined. Medical treatment when started early should cure endocarditis in most patients, but vigilance should be maintained for the appearance of indications for surgery. When such indications exist surgery should not be delayed.

Longterm effects of cryosurgery in the sheep heart.

This study concerns the longterm effects of both epicardial and endocardial cryosurgery with particular reference to the coronary arteries. Sheep were subjected to epicardial cryosurgery without cardiopulmonary bypass, and to endocardial application with bypass. In both groups the heart was kept beating throughout the operation. Neither cardioplegia nor aortic cross-clamping was used. In the first group applications were made for 5 min directly over or adjacent to a major branch of the left coronary artery. In the second, the cryoprobe was applied for 5 min or until atrioventricular dissociation occurred. No sheep developed late arrhythmias or evidence of myocardial ischaemia. Only minimal arterial changes were observed and all the major coronary arteries remained widely patent. Cryothermia to the heart produced a small discrete lesion without complication. Bright fluorescence of necrotic myocytes was observed in all the immature lesions when sections stained with haematoxylin and eosin were examined under ultraviolet light. This vivid fluorescence clearly delineated the extent of the lesions and persisted while cytoplasmic elements remained. Our results indicate that cryosurgery provides a safe and permanent technique for the surgical treatment of arrhythmias in man, and may safely be used even in proximity to the coronary arteries. Cardioplegia is contraindicated.

Reoperation for failed aorto-coronary bypass grafts.

Despite the initial overall good results of aorto-coronary bypass grafting for myocardial revascularisation, a small but increasing number of patients require consideration for reoperation after the first procedure. In the period 1973 to 1981, 36 reoperations were performed in 34 patients with one operative death. In all of them the clinical indication for reoperation was recurrence of angina pectoris. In this special group of patients a high incidence of risk factors was present. Three major probable causes for the recurrence of angina were found: (1) Progression of the coronary atherosclerotic disease; (2) Graft failure; (3) Incomplete original revascularisation. Combined factors were present in 18 (53%) patients. There were no statistically significant differences in the incidence of postoperative complications at the first and second operation. Follow-up of 79% of the 33 survivors over a mean time period of 18 months, demonstrated no late mortality and a low subsequent infarction rate. Overall 69% of patients either lost their angina or were improved. We therefore conclude that reoperation can be accomplished with low mortality and morbidity and has a potential therapeutic benefit in the majority of cases.

A comparison of two prophylactic antibiotic regimes for open-heart surgery.

Two groups of patients undergoing open-heart surgery were given prophylactic courses of antibiotic lasting five days. One group (61 patients) received a cephalosporin and the second (57 patients) received a combination of penicillin, flucloxacillin and streptomycin. The overall major infection rate was low (3--4%), particularly so in the cephalosporin group (1.6%). There was no increased nephrotoxic effectt of the cephalosporin, and any nephrotoxic effect that was present was temporary and clinically unimportant. The major infecting organism in both groups was Staphylococcus albus (Staph. epidermidis). The efficiency, therefore, of any prophylactic regime which omits gentamicin, to which Staph. albus in usually sensitive, remains in doubt.

Electrophysiological manifestations of non-penetrating cardiac trauma.

Electrophysiological disturbances were observed in four cases of non-penetrating cardiac trauma. Ventricular tachycardia occurred both as an early and late complication in three, responding to medical treatment in two; it was cured by cryoablation in the other case. The fourth patient developed an isolated conduction defect associated with anteroseptal myocardial infarction, the coronary arteries and left ventricular function being normal.

Return to work and quality of life after surgery for coronary artery disease.

Changes in work capability and quality of life were assessed retrospectively in 130 patients with ischaemic heart disease who had undergone aortocoronary bypass operations during 1976-7 because of medically uncontrollable angina. A total of 85 patients (65.4%) reported complete relief from angina six months after operation, though 12 later suffered a recurrence. Substantially fewer patients needed drugs after the operation. Before operation 9 out of 117 men fully employed at the onset of angina were working without restriction or doing lighter, fulltime work, 38 were at work but seriously incapacitated by angina, and 70 were forced to stop work. After operation 70 were working without restriction or engaged in lighter work, 15 were at work but still restricted by angina, and only 32 were forced to stop work. This result was highly significant (P less than 0.001). These differences were even more pronounced in heavy manual workers, of whom none cobld work normally before operation, whereas 16 were working without restriction afterwards. Of patients wishing to engage in hobbies or sports, social activity, and sexual intercourse but were restricted before operation, about two-thirds could resume these activities afterwards. Coronary artery surgery provided dramatic symptomatic relief in up to 90% of patients and permitted rehabilitation and return to gainful employment irrespective of type of labour. The degree of symptomatic improvement and increase in exercise tolerance after successful surgery is usually far greater than occurs with any other form of treatment and directly improves quality of life and work capability.