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Biomedical subjects

S R Large

Publications and source records attributed to S R Large.

At least 55 records · Page 3Linked to original sources
PubMed1994

Heart-lung transplantation in situs inversus and chest wall deformity.

Heart-lung transplantation in the presence of complex congenital heart disease including situs inversus and significant chest wall deformity can be accomplished successfully. However, the postoperative course is apt to be prolonged because of mechanical respiratory problems, which will respond to a protocol of weaning and nutritional supplementation.

Adult↗
PubMed1994

Using "unsuitable" hearts for transplantation.

Donor availability is the single most limiting factor in heart transplantation. From a consecutive series of 100 heart donors, there were 21 which fell well outside our minimum criteria on initial inspection: mean arterial pressure (MAP) more than 60 mm Hg, central venous pressure (CVP) less than 12 mm Hg, pulmonary capillary wedge pressure (PCWP) less than 12 mm Hg, left ventricular stroke work index (LVSWI) more than 15 g.m. on inotropes less than 5 mcg/kg per min. Of these 13 out of 21 had a MAP less than 55 mm Hg, 6 out of 21 a CVP more than 15 mm Hg and 2 out of 21 were on inotropes at more than 20 mcg/kg per min. Following full invasive monitoring another 14 donors fell outside our criteria; 5 had a mean LVSWI of 12.4 g.m. and 9 had a mean PCWP of 19.6 mm Hg. Following the institution of our hormone-based pharmacological resuscitation regime 30 of these donors yielded 19 transplantable hearts and 11 transplantable heart-lung blocks. The other five were not used due to left ventricular hypertrophy (2), inotrope dependency (2) and persistent poor function (1). Twenty-five of the 30 recipients of these organs (83.3%) are alive and well, 4-25 months post transplant. Four early deaths occurred; one arrhythmia (heart), one acute respiratory distress syndrome (heart), one cerebrovascular accident (heart lung) and one infection (heart, lung and liver). One death occurred at 90 days from tamponade (heart). Aggressive and focussed donor management has helped us to maintain our levels of transplant activity, without compromising the outcome--a 30-day mortality of 16.2% in 1989, 11.8% in 1990 and 6.8% in 1991.

Blood Pressure↗
PubMed1994

Sternal wound dehiscence after internal mammary artery harvesting. Logical management.

There is clear evidence that the internal mammary artery is superior to other forms of vascular conduit in surgical coronary revascularisation. Its patency rate at 10 years is of the order of 2-3 times that of autologous saphenous vein. Unfortunately, harvesting of the internal mammary is associated with an increased incidence of sternal wound complications, probably due to temporary sternal devascularisation. The restoration of sternal blood supply has been shown to occur after several weeks. It is proposed by this group that delayed primary closure of dehisced wounds after 3-4 weeks is an effective way of dealing with this malignant and, fortunately, rare complication of arterial coronary artery revascularisation.

Humans↗
PubMed1994

Risk factors for survival following combined heart-lung transplantation. The first 100 patients.

As the numbers of heart and lung transplant recipients have increased it has become possible to identify major risk factors for early (within 3 months) and later (after 3 months) death after this procedure. For 100 patients receiving organs between April 1984 and February 1991, and followed up until February 1992, patient characteristics, operative details, and early morbidity were assessed for their effects on early and later deaths. Recipient age, sex, and preoperative diagnosis did not have a significant effect on early (within 3 months) or later death. Positive cytomegalovirus antibody status of donor or recipient conferred greater risk of death within 90 days (odds ratio [OR] = 3.24, P = 0.06). Greater than 2 L blood in the first 24 hr after operation (OR = 6.00, P = 0.05), and ventilation for greater than 24 hr (OR = 4.87, P = 0.006) were significant prognostic indicators of early death. After the first 3 months, the main risk factor for death was rejection in the first 3 months (OR = 1.38 per episode, P = 0.008). Early infection in general and CMV infection in particular were associated with a small increase in risk. This study confirms the importance of matching donor and recipient for CMV and shows that difficulties during operation, reflected in postoperative bleeding and ventilation times increased the chance of early death. Later death was associated with early acute rejection. A detrimental effect of infection, including CMV infection, either does not exist, or is too small to be detected in a study of this size.

Actuarial Analysis↗
PubMed1994

Maze 3 for atrial fibrillation: two cuts too few?

The Maze procedure has been developed as a surgical approach to the management of patients with atrial fibrillation refractory to medical treatment. The recent modification of the technique (Maze 3) achieves good rate control with coordinated AV contractions. However, the procedure involves cuts that completely isolate a block of left atrial (LA) wall, including the four ostia of the pulmonary veins. The electrical and mechanical activity of this isolated LA block are dissociated from the rest of the atrium, and the area may, in fact, continue to fibrillate. This may provide a nidus for the development of mural thrombus. The weight and endocardial surface area of the LA block and of the entire LA were estimated in ten formalin fixed hearts from trauma victims with no evidence of cardiac disease. In these samples, the LA block represented 35% of the endocardial surface area of the entire LA and 29% of the weight. The LA block is of sufficient size to allow macroreentrant circuits to form and has the potential to fibrillate if isolated from the rest of the atrium. We modified the Maze 3 procedure to recruit the otherwise isolated LA block by using two additional cuts around each pair of pulmonary veins as they enter the LA. The first patient who underwent the modified procedure demonstrated sinus rhythm on Holter monitoring postoperatively and remained in sinus rhythm following burst atrial pacing at 300 and 420 beats/min each for 30 seconds. In addition, atrial contractions were found to contribute 19% of the cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗
PubMed1992

Error rates with which endomyocardial biopsy specimens are graded for rejection after cardiac transplantation.

Control of the immune response to the transplanted organ is fundamental to the success of transplantation. Endomyocardial biopsy to diagnose and grade rejection is the mainstay in achieving this control. As rejection tends to be a patchy process, accurate diagnosis depends on adequate sampling from the myocardium. This study estimates the error rates with which biopsy specimens are graded. The results of 459 biopsy sets, in which at least 4 fragments were graded, were analyzed. Combinations of grades observed at the same biopsy session were used to estimate error rates. An E-M algorithm was used to estimate error rates. Predictive probabilities of true grades, given a set of 4 graded fragments, were calculated using Bayes theorem. If 4 fragments at a biopsy session were negative there was a 0.02% chance of missing clinically significant rejection (moderate or severe). Similarly, if minimal rejection was the highest grade observed, the probability of missing moderate-severe rejection was negligible, between 0.06 and 0.09%. However, where mild rejection is the highest observed on the 4 fragments, there is between a 2% (1 mild fragment) and 28% (4 mild fragments) chance of moderate-severe rejection being the underlying grade. This study concludes that 4 fragments are adequate as a minimum in most cases. However, if only 4 fragments are available, and greater than or equal to 3 are graded mild, the risk of missing moderate-severe rejection is unacceptably high, and repeat biopsy or treatment may be indicated.

Biopsy↗
PubMed1992

Coronary flow reserve and coronary occlusive disease.

The functional effects of coronary occlusive disease (COD) in cardiac transplant patients on small-resistance coronary vessels are unclear. We investigated the changes in coronary flow reserve (CFR) in response to the non-specific smooth muscle vasodilator papaverine. A 3F Doppler probe was inserted into the left anterior descending (LAD) coronary artery in 61 patients following orthotopic heart transplantation. Studies were performed in 57 males and 4 females with a mean age of 46 years (range 20-61 years). The median time from operation was 4 years (range 3 months to 10 years). Coronary blood velocity was measured at rest (RFV) and maximum hyperaemia (PFV) produced by intracoronary papaverine. Coronary flow reserve (CFR) was defined as the ratio of PFV to RFV. Minor lesions in epicardial vessels were found in 23 transplant patients. The mean percentage diameter of the most severe lesion in the coronary tree was 23% SD 3% including 12 lesions in the LAD coronary artery itself (mean 24% SD 4%). Patients with COD had an impaired CFR (2.6 SEM 0.2) compared with normals (3.9 SEM 0.2, P = 0.0003), adjusting for year after operation. Mean resting flow velocity was similar in both groups (minor COD, 6.8 cm/s SEM 1.2; normals, 7.1 cm/s SEM 0.6), but mean peak flow velocity response to papverine was reduced (16.5 cm/s SEM 2.5 versus 27.3 cm/s SEM 2.6; P = 0.007). In the presence of minor epicardial disease, coronary flow reserve in resistance vessels was reduced due to impairment of peak flow. This demonstrates that non-endothelial-dependent coronary resistance vessel vasodilatation is abnormal and may be caused by a defect in vascular smooth muscle function.

Blood Pressure↗
PubMed1992

Coronary artery bypass grafting nine years after cardiac transplantation.

Angina and increasing exertional dyspnea developed in a 53-year-old man 9 years after cardiac transplantation. Left heart catheterization revealed severe proximal triple coronary artery disease, and he underwent surgical revascularization. Now 18 months after the operation he continues to be free of symptoms.

Coronary Angiography↗
PubMed1992

Pleural effusions: is thoracoscopy a reliable investigation? A retrospective review.

In this paper, we consider the results of thoracoscopy in a busy thoracic unit where the referring physicians place their greatest emphasis upon simple standard investigation of pleural disease. Between 1985 and 1989 620 patients with a pleural effusion of unknown aetiology were referred to our thoracic medical unit. Initial investigations included aspiration of pleural fluid for cytology and culture, and blind pleural biopsy for histological examination. Recourse to thoracoscopy was only taken in the absence of a diagnosis or non-resolution of the patients symptoms and signs. Of these 620 patients only 48 (8%) remained without a diagnosis and were referred for thoracoscopy. Histological assessment of biopsies obtained at thoracoscopy revealed malignancy in 24 patients (50%) and benign conditions in 16 patients (33%). In eight patients (17%) no conclusive diagnosis was established; in this latter group, six patients continued with their symptoms and further invasive investigations revealed malignancy. In this setting where thoracoscopy was used as a last resort, the sensitivity for thoracoscopy was 83% and the specificity was 100% with a predictive value of a negative result being 25%. In conclusion, from our experience, the majority of pleural disease may be diagnosed using simple techniques but thoracoscopy can be very helpful in the more complex cases. Moreover, inconclusive histology following thoracoscopy is an indication for further investigation if the condition does not improve.

Adult↗
PubMed1992

Coronary occlusive disease and late graft failure after cardiac transplantation.

OBJECTIVE: Coronary occlusive disease is the main cause of late mortality after cardiac transplantation. It has both similarities and differences compared with conventional atherosclerotic coronary disease. The pathophysiology of late graft failure from coronary occlusive disease is unclear at present. We reviewed the experience of this disorder in our cardiac transplant programme. DESIGN: A retrospective analysis of angiographic and pathological data. SETTING: A regional cardiothoracic centre and transplant unit. PATIENTS: Of a population of 383 orthotopic cardiac transplant recipients operated upon between January 1979 and June 1990, 447 coronary angiograms were available for review in 193 patients. Thirteen of a possible 18 results of post mortem examinations from patients dying from coronary occlusive disease were available. MAIN OUTCOME MEASURE: Coronary occlusive disease was defined as any evidence of disease on coronary angiography. Post mortem examinations were performed with standard techniques. RESULTS: The angiographic prevalence of coronary occlusive disease was 3% (1/32 patients) and 40% (19/47 patients) at one and five years respectively. Twenty six grafts failed due to coronary occlusive disease compared with 132 graft failures from all causes during this period. Acute thrombosis was present in a large vessel in seven of 13 fatal cases undergoing necropsy (54%). Noticeable large vessel involvement with disease in smaller distal vessels was present in four patients (31%). The remaining two patients (15%) had small vessel disease alone. Twelve of the 13 patients had significant cardiomegaly (cardiac weight > or = 400 g) with a mean weight of 510 (range 370-740) g. CONCLUSION: Coronary occlusive disease is the main late complication after cardiac transplantation. A combination of coronary thrombosis, ischaemia from stenoses of large and small coronary vessels, and cardiomegaly contribute to the graft failure of these patients.

Adolescent↗