Biomedical subjects
Publications and source records attributed to R S Bonser.
We report the case of a 67-year-old, diabetic patient who underwent antibiotic-preserved homograft replacement of a thoraco-abdominal segment of the aorta for leaking mycotic aneurysm. This was successful in eradicating the sepsis and no graft complication had occurred at (18 months). Follow-up with computed tomography (CT) scanning.
OBJECTIVE: Retrograde cerebral perfusion (RCP) via the superior vena cava has been described as an adjunctive technique to enhance the safety of hypothermic circulatory arrest (HCA), but perfusion of cerebral tissue in humans during RCP has not been demonstrated to date. We report our clinical experience with RCP and our attempt to demonstrate "true" perfusion of the brain. METHODS: Between April 1993 and June 1995, 49 thoracic aortic procedures were performed in 48 patients (male:female = 26:22) (emergency: elective = 25:24). The indications for surgery were acute type "A" dissection (18) chronic aneurysm (28) and infected valved conduit (3). Hypothermic circulatory arrest (15 degrees C) and RCP were implemented in all cases (mean HCA time 29 min, range 11-69) (mean RCP time 26 min, range 10-65). The 99mTechnetium labelled brain perfusion agent d,l, hexamethyl propylene amine oxime (99mTc-HMPAO) was administered (100 MBq) into the cardiotomy reservoir following institution of HCA (15 degrees C) in three consecutive patients and planar dynamic brain imaging with a portable gamma camera was commenced at the start of RCP. RESULTS: Six hospital deaths (12.2%) occurred in the emergency group due to atheromatous embolic stroke in one patient, sepsis in one, ruptured infrarenal aortic aneurysm in one, myocardial failure in one, renal failure in one and multi-system organ failure in one patient. The remaining patients suffered no major neurological complications (median Intensive Care Unit stay 1 day, range 1-5). Inspection of the images acquired showed 99mTc-HMPAO activity spreading quickly from the jugular bulb and the superior sagittal sinus throughout the cerebral white and gray matter. Time-activity curves calculated for both cerebral hemispheres showed homogeneous regional cerebral perfusion. CONCLUSIONS: Retrograde cerebral perfusion is easy to establish, "safe" and provides blood flow to the brain during HCA. The flow quantification and metabolic contribution of RCP require further investigation.
OBJECTIVE: Elevated pulmonary vascular resistance and transpulmonary gradient are predictors of increased perioperative mortality in patients undergoing orthotopic heart transplantation. Sodium nitroprusside and prostacyclin PGI2 are routinely used to assess the reversibility of pulmonary vascular resistance and transpulmonary gradient in heart transplant candidates, but their use is limited by their systemic vasodilatory effect. The aim of this study was to evaluate the systemic and pulmonary haemodynamic effects of low concentration (10 and 20 parts per million) inhaled nitric oxide in patients with severe heart failure with elevated transpulmonary gradient and pulmonary vascular resistance undergoing assessment for cardiac transplantation, and to compare the haemodynamic effects of inhaled nitric oxide with those of sodium nitroprusside and prostacyclin PGI2. METHOD: In 10 consecutive patients with elevated transpulmonary gradient (16+/-2 mm Hg) and pulmonary vascular resistance (3.6 +/-0.3 Wood units (WU)) nitric oxide (10 and 20 parts per million in 23% inspired oxygen (O2) via a tight fitting facemask) and increasing doses of intravenous sodium nitroprusside and prostacyclin were administered in a random, single-blinded fashion. RESULTS: Inhalation of nitric oxide (10 ppm) reduced the transpulmonary gradient (-7+/-2 mm Hg; P<0.01) and pulmonary vascular resistance (-1.8+/-0.4 WU; P<0.001) but did not affect the systemic vascular resistance (-0.3+/-1 WU) or mean systemic arterial pressure (-1.3 5 mm Hg). Sodium nitroprusside and prostacyclin reduced the transpulmonary gradient (-4.5+/-2 mm Hg; P<0.01 and -3.6+/-2 mm Hg; P<0.05), pulmonary vascular resistance (-1.5+/-0.4 WU; P<0.001 and -1.3+/-0.4 WU; P<0.01), systemic vascular resistance (-7+/-2 WU; P<0.01 and -7.2+/-2 WU; P<0.01) and mean systemic arterial pressure (-15+/-5 mm Hg; P<0.01 and -18+/-4 mm Hg; P<0.01). CONCLUSION: Low-concentration inhaled nitric oxide is as effective as sodium nitroprusside and prostacyclin in reducing transpulmonary gradient and pulmonary vascular resistance, and is highly pulmonary vasoselective.
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AIMS: To evaluate an immunohistological stain for complement component C9 as a method of detecting early myocardial infarction and to compare this with (1) an enzyme histochemical method and (2) conventional histological staining. METHODS: (1) Eight hearts taken at necropsy were stained using the nitroblue tetrazolium/phenazine methosulphate method and an immunohistological stain for C9. (2) Twenty five hearts from cases of suspected or confirmed myocardial infarction and 25 from cases without conventional evidence of infarction were stained for C9 and by haematoxylin and eosin. RESULTS: (1) The histochemical method indicated myocardial necrosis in five hearts and the C9 method in seven, all of which had clinical evidence of myocardial damage or a reason for it. The histochemical method required fresh myocardium, was difficult to use and was difficult to interpret. (2) Of 25 hearts with suspected or confirmed infarction, 24 were stained by the C9 method. Staining with haematoxylin and eosin showed infarction in 16 of these, all with infarcts at least 24 hours old; the other eight had clinical evidence of infarction less than 24 hours old. The heart not stained by C9 was from a patient who, on review, had no evidence of infarction. Of the 25 control hearts, none had infarction on staining with haematoxylin and eosin, but three were stained by the C9 method. These three were from patients with septicaemia or another reason for myocardial damage. CONCLUSIONS: The immunohistological method for C9 is a simple, reliable and sensitive method for the detection of early myocardial necrosis that could be used on formalin fixed, paraffin wax embedded necropsy material. This had advantages over a histochemical method and conventional staining with haematoxylin and eosin.
We describe a patient with post-infarction left ventricular rupture exhibiting several atypical features. A successful outcome was achieved after serendipitous surgery.
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We recently have used retrograde cerebral perfusion via the superior vena cava in association with hypothermic circulatory arrest as an adjunct to cerebral protection during aortic arch operations. Between April 1993 and March 1994, 23 patients (14 male; 9 female; median age, 64 years; age range, 25 to 76 years; 14 emergency, 9 elective) underwent operation on the ascending aorta, aortic arch, or both for acute dissection (11) or aneurysm (12). Aortic root replacement was performed in 13 patients (7 with arch replacement), ascending aortic replacement in 7 (4 with arch replacement), isolated aortic arch replacement in 2, and repair of sinus of Valsalva aneurysm in 1. Coronary artery bypass grafting was performed in 4 patients. Hypothermic circulatory arrest (15 degrees C) and retrograde cerebral perfusion were implemented in all cases (median circulatory arrest time, 21 minutes; range, 13 to 51 minutes; median retrograde cerebral perfusion time, 20 minutes; range, 12 to 50 minutes). Three hospital deaths occurred (atheromatous embolic stroke, sepsis, rupture of infrarenal aortic aneurysm). The remaining patients had no neurologic damage (median intensive therapy unit stay, 1 day; range, 1 to 5 days). Retrograde cerebral perfusion is easy to establish and safe, and may improve brain protection during hypothermic circulatory arrest.
A 45-year-old female presented with typical recent-onset exertional angina pectoris. Subsequent investigation showed that the likely cause was an aberrant origin of the right coronary artery arising from the left coronary sinus. This anomaly is uncommon and is not usually associated with angina pectoris. Surgical rerouting of the origin of the right coronary artery produced complete resolution of ischaemia.
Seventeen patients with severe ischaemic heart failure without angina were studied prospectively to determine the effects of surgical revascularization on exercise tolerance, peak oxygen consumption and left ventricular function at rest and during inotropic stimulation at 3 months after surgery. Suitability for surgery was assessed by the presence of ischaemia identified by thallium scintigraphy and stress electrocardiographic (ECG) testing and the left ventricular response to dobutamine measured by radionuclide ventriculography. One patient died awaiting surgery and one required cardiac transplantation. Fifteen patients underwent coronary artery surgery with two perioperative deaths. Thirteen patients were restudied 3 months after surgery. Mean treadmill exercise time (362 +/- 204 s to 562 +/- 303 s, P < 0.05) and peak oxygen consumption (14.9 +/- 3.5 ml/kg per min to 20.8 ml/kg per min, P < 0.01) increased significantly. Resting ejection fraction was not changed after surgery (20 +/- 5% to 21 +/- 6%) but ejection fraction during derived from thermodilution Swan-Ganz catheter data both at rest during dobutamine stimulation were unchanged after surgery. At 13 +/- 3 months after surgery there had been three sudden deaths and one patient had undergone successful cardiac transplantation. Of the remaining nine patients, three had improved to NYHA symptomatic class I, three were in NYHA class II and three in NYHA class III. Repeat treadmill exercise testing in seven patients showed that the improvement in exercise capacity evident in the first follow-up visit was maintained during long-term follow-up.
I.m. temperature probes were used in humans during and after hypothermic cardiopulmonary bypass (CPB). After rewarming to apparent normothermia of the body core, we found that the temperature of the vastus lateralis muscle remained well below the nasopharyngeal temperature at the time of weaning from bypass. This reduced muscle temperature represents a considerable deficit in total body heat which may account for a large proportion of the afterdrop in temperature which occurs in the postoperative period. There was no morbidity associated with the use of the i.m. probes which could be incorporated into standard clinical practice.
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Ten male patients with a mean age of 57.5 years (range 27-75 years) underwent homograft aortic valve or root replacement for destructive aortic valve endocarditis. Six patients had native valve endocarditis (one with associated native mitral valve endocarditis) and four had prosthetic valve endocarditis (one with associated prosthetic mitral endocarditis). Causative organisms were Streptococci in six patients, Staphylococci in one, Q fever in one and no organisms were isolated in the remaining two patients. All the patients were operated while on antibiotics (mean lengths of treatment 13 days; range 2-42). The main indication for surgery was cardiogenic shock in five patients, progressive cardiac failure in four patients and uncontrolled sepsis in one patient. Operative procedures involved homograft aortic root replacement with coronary reimplantation (seven patients; associated prosthetic mitral valve replacement in one patient), infracoronary homograft aortic valve replacement (three patients) and a number of other procedures were performed to reconstruct the disrupted cardiac anatomy. Patients were followed up for a mean of 13.2 months (range 2-21). One patient died 4 months postoperatively of an unrelated cause; all the others are asymptomatic with no evidence of recurrent endocarditis. We conclude that homograft aortic valve or root replacement is an effective method of managing destructive aortic valve endocarditis.
OBJECTIVE: To determine the incidence and outcome of refractory cardiac arrest necessitating emergency coronary artery bypass grafting. DESIGN: Retrospective survey of cardiac catheterisation and surgical records. SETTING: The London Chest Hospital. PATIENTS: All patients requiring emergency coronary artery bypass grafting after cardiovascular collapse in the catheterisation suite between January 1984 and December 1989. MAIN OUTCOME MEASURES: Incidence of refractory cardiac arrest in the study group and perioperative mortality. RESULTS: Thirteen of 8675 patients undergoing coronary arteriography or angioplasty had refractory cardiac arrests. Five patients died, but the remainder survived to be discharged from hospital without serious morbidity. CONCLUSION: Without immediate surgical intervention the mortality for these 13 patients would have been 100%.
Serial complement estimations during cardiopulmonary bypass are reported in a patient with acquired C1 esterase inhibitor deficiency. Although the extent of classic and alternative pathway activation appeared appropriate, exaggerated common pathway activation with massive increase in the C3d:C3 ratio occurred. A fatal hemostatic disorder, pulmonary edema, and circulatory collapse ensued despite prophylaxis and therapy.
Complement activation is believed to be of importance in the development of complications arising after cardiopulmonary bypass. The effect on complement activation of priming the extracorporeal circuit with crystalloid alone, crystalloid plus albumin, or crystalloid plus the plasma expander polygeline was assessed in 36 patients undergoing coronary artery operations with cardiopulmonary bypass using a bubble oxygenator. Activation of the alternative and common complement pathways was monitored before, during, and after the bypass period by measuring concentrations of factor B and its fragment Ba and C3 and its fragment C3d. Complement activation occurred in all three groups of patients, with no difference between the crystalloid and crystalloid-albumin groups. In contrast, Ba fragment concentrations were persistently and significantly lower during and after bypass in the polygeline group, denoting reduced complement activation. C3d levels also showed a tendency to be lower in this group. Our results indicate that addition of polygeline to the priming solution reduces complement activation. Because complement activation is associated with morbidity after cardiopulmonary bypass, addition of polygeline to the priming solution may offer an inexpensive method of reducing morbidity after cardiopulmonary bypass.
Plasma levels of the complement parent molecules C3, C4, and factor B and their split products, C3d, C4d, and Ba were measured in 12 patients undergoing cardiopulmonary bypass for coronary artery surgery. Alternative and common complement pathway activation, demonstrated by statistically significant rising levels of Ba (P less than 0.05), and C3d (P less than 0.05) and by elevated Ba:B (P less than 0.05) and C3d:C3 (P less than 0.05) ratios were found before the institution of cardiopulmonary bypass but following heparin administration suggesting that heparin may itself initiate alternative pathway activation. In addition, significant depletion of parent complement components and elevation of split product concentrations was seen during bypass suggesting classical and alternate pathway activation (P less than 0.01). This study clarifies the pathways of complement activation during bypass and presents evidence that heparin administration may initially activate the complement cascade.
A canine double-lung allotransplantation model was developed to study the effects of 12-h static pulmonary preservation. This model has not been used extensively for such experiments but allows a detailed evaluation of the quality of preservation. An operative technique is described in which cautery dissection and preliminary devascularization of the recipient right lung allows the period of cardiopulmonary bypass to be limited and reduces postoperative bleeding. Six double-lung blocks were successfully orthotopically transplanted and recipient animals were studied for 12 h postoperatively. All animals survived the study period and had a mean PO2 (FIO2 0.4) of 141 mm Hg, 12 h following reimplantation suggesting adequate pulmonary preservation. There was no evidence of pulmonary edema at any time following implantation, although airway pressures and pulmonary vascular resistance were elevated. The role of this model in lung preservation studies is discussed.