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Biomedical subjects

S C Lennox

Publications and source records attributed to S C Lennox.

47 records · Page 3Linked to original sources

Protein C deficiency associated with massive cerebral thrombosis following open heart surgery.

We describe a case of massive cerebral venous thrombosis following open heart surgery in a patient with a reduced level of Protein C (40% of mean level). Protein C deficiency is an inherited disorder which in the homozygous form may result in massive fatal venous thrombosis in the newborn. A Protein C level below 55% is highly suggestive of heterozygous deficiency and has been associated with a tendency to venous thrombosis although its clinical penetrance is variable. This is the first reported case of massive venous thrombosis in a patient following open heart surgery associated with Protein C deficiency.

Aged↗

Reduction of blood use in surgery for coronary artery disease.

Ninety consecutive patients underwent surgery for coronary artery disease. Eighty-one (90%) did not require blood transfusion in the immediate postoperative period; nine patients received 16 units of blood, 6 of whom bled excessively; 2 were re-explored. Twelve had post-operative haemoglobins below 8.5 G/dl during their stay. They were transfused a total of 28 units of blood before discharge. Post-operative blood loss in the 9 transfused early averaged 894 +/- 176 ml (SEM). Loss from the not transfused patients averaged 481 +/- 18 ml (p less than 0.001). Patients transfused later had a mean loss of 510 +/- 36 ml (P NS). Sixty-nine patients were not transfused. Haemoglobin on the first post-operative day was 11.3 +/- 1.3 G/dl (SD). This declined to 10.2 +/- 1.2 G/dl on the fifth day. Discharge haemoglobin was 10.5 +/- 1.2 G/dl. Two patients died, one of myocardial infarction on the third day and the other of pancreatitis on the fourth. Both had had early blood transfusion. Haemoglobins were above 10 G/dl. Of the 69 untransfused patients 17% had supraventricular arrhythmias. Ten percent had serous wound discharges; 3 were infected. There were no sternal dehiscences. It is concluded that bank blood transfusion with its attendant hazards and expense is easily avoidable in most patients. This saving of resources will increase the availability of blood and rare groups for surgery.

Adult↗

The effects of low flow, low pressure pulsatile bypass.

The effects of low flow low pressure pulsatile bypass were studied in 90 consecutive patients undergoing coronary artery surgery. Overall pump flow rate (OFR) was 19-49 (mean 31 +/- 7) ml/kg/min at all temperatures. Moderate (28 degrees C) hypothermia was used. When cross-clamped flow was 17-49 (mean 27 +/- 7) ml/kg/min and mean perfusion pressure 50-60 mmHg. Priming volume (PV) was reduced to 1.45 +/- 0.02 L (range 1.2-2.0 L) PV, cardioplegia and volume additions were considered as total bypass crystalloid (TBC) and this correlated positively with increased post-operative positive water balance (r = 0.58, P less than 0.001). Bypass urine output averaged 135 +/- 24 ml (range 0-1,000 ml) was unrelated to OFR and correlated only with TBC (r=0.47, P less than 0.001). In 86 a single cardioplegia dose of 0.7 L (range 0.4-0.8 L) sufficed for this ischaemic period (mean 46 +/- 16 min). Four required a further 0.2-0.3 L. Their ischemic times were 44-74 min (mean 59 +/- 13 PNS). Inotropes were used in only 3 patients. Post-operatively 7 required diuretics for low hourly urine flow. Of the 76 with normal pre-operative renal function urea rose transiently in 15. Three had raised urea for over 9 days. Creatinine rose transiently in 7 but persisted in only one. Plasma cortisol (n=78) rose in 67 and fell in 11, indicating, overall, an adequate metabolic response. Plasma free haemoglobin before and after bypass varied widely and did not correlate with flow rate or perfusion time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Evaluation of synthetic and biosynthetic conduits used as aorto-pulmonary shunts in growing pigs.

Synthetic and biosynthetic conduits 6 mm in internal diameter and 3 cm long were implanted as aorto-pulmonary shunts in 4 week old piglets. The synthetic conduit was made of Polytetrafluoroethylene (P.T.F.E.) manufactured by Gore-Tex; the biosynthetic graft was prepared by tanning bovine ureters and covering it with a polyester mesh. Two groups of six animals for each conduit underwent operation. Following implantation, when the animals were physiologically stable, the pressure and blood flow were measured in the pulmonary artery, conduit and aorta, and at the same time blood gases were obtained. These measurements were repeated four weeks later, following which the grafts were excised and processed for histological studies. All the conduits were patent, 4 weeks after implantation, but whereas there was little difference in the flows through the bovine grafts (506 ml/min) there was a marked reduction in the flow through the Gore-Tex conduit (235 ml/min). These differences could be related to the changes seen histologically. No drugs were used to affect patency of the conduits in this study.

Animals↗

The results of surgery for active endocarditis of the native aortic valve.

Between 1968 and 1981, 40 patients with active endocarditis of the native aortic valve were treated by aortic valve replacement (A.V.R.). There were 8 postoperative deaths (hospital mortality 20%). This included 5 patients who had developed cardiogenic shock prior to surgery. Antibiotic treatment for less than one week and positive cultures on the excised valve had poor prognostic implications but tended to be associated with irreversible haemodynamic failure. Twenty five patients underwent A.V.R. following the onset of severe pulmonary oedema. The hospital mortality in this group was 28% and the 5 year actuarial survival 56% (+/- 11%). Fifteen patients who had developed premature closure of the mitral valve (P.C.M.V.) on M-mode echocardiography but who had no overt signs of cardiac failure underwent A.V.R. with a single death (7% hospital mortality). The 5 year actuarial survival in this group was 87% (+/- 9%). P.C.M.V. is a useful prognostic sign identifying those patients with endocarditis on the native aortic valve likely to benefit from early surgery.

Adolescent↗

Long-term survival following left ventricular aneurysmectomy.

Ninety-four patients who underwent left ventricular aneurysmectomy between 1971 and 1980 are reviewed. In thirty-four cases this operation was combined with myocardial revascularisation. The overall hospital mortality was 6% with a five-year survival of 72% +/- 6%. Symptomatology dominated by dyspnoea, a raised left ventricular end diastolic pressure (L.V.E.D.P.) and ventricular dysrhythmias adversely affected survival. Combined myocardial revascularisation did not affect the hospital mortality but was associated with a trend toward improved long-term survival in two groups of patients viz those presenting with predominant angina and those with major stenoses of two or more coronary arteries. Fifteen patients agreed prospectively to post-operative cardiac catheterisation. Despite symptomatic relief no improvement in L.V.E.D.P. or ejection fraction was demonstrated in this group.

Angina Pectoris↗

The management of prosthetic valve endocarditis.

During the period 1970 to 1980 2,945 patients underwent valve replacement at the Brompton Hospital. Thirty-one (1%) patients subsequently developed prosthetic valve endocarditis (P.V.E.). Twenty-one (0.7%) patients developed endocarditis within two months of valve replacement. Ten patients were treated medically, with seven deaths, whilst four of the eleven surgical cases died. There were ten cases of late P.V.E. occurring between two months and eight years after initial valve replacement (0.12% per annum). Eight patients were treated surgically, with two deaths, whilst both medical cases died. Thus 67% patients were effectively treated by immediate valve replacement, whilst only 25% medical cases survived. Actuarial survival curves predict a 41% five-year survival following surgery for P.V.E. We stress the importance of early diagnosis of this condition and recommend immediate valve replacement in all patients with P.V.E. developing signs of haemodynamic failure.

Adult↗

Aorto-pulmonary window.

Aorto-pulmonary window (septal defect) is an uncommon congenital cardiac malformation accounting for only about 0.5% of the cases of congenital heart disease catheterised at our institution. Of 15 patients with this anomaly eight had associated cardiac malformations. Three patients presented in the neonatal period and in these patients the other cardiac anomalies (aortic interruption in two, pulmonary atresia in one) determined the clinical presentation and haemodynamic disturbance. A second group of five patients presented with heart failure during infancy and in these patients additional anomalies, present in three, were "incidental" findings. A third group of seven patients with similar physical signs but without heart failure did not present until after the first year of life and all were asymptomatic. Associated anomalies, present in two, were again "incidental" in that they did not influence the presentation. Of 12 patients without serious associated anomalies, five, operated on before 1970, had division and suture of the aorto-pulmonary window with one death. In two the defect was patched from the pulmonary artery but one required re-closure from the aorta. In six the defect was successfully patched from the aorta, which is now the preferred technique.

Adolescent↗