Postnatal development of the pig heart.

The small amount of data concerning the normal postnatal development of the pig heart has prompted us to study and quantify these changes from birth to the sixth month of postnatal life. The method used consisted of separation of the various cardiac components. Their individual weights are assessed, and width and length of both ventricles were determined. The free wall myocardial thickness of both ventricles was also measured. Major differences in the growth pattern of the ventricles were clearly shown. At birth the free will of the left ventricle was already thicker than that of the right ventricle. This difference became more accentuated with growth. Similar findings in terms of mass were found, but the difference between the two free walls was reduced. There was disproportionate postnatal growth in favour of the left ventricle in all measurements taken except length. The right ventricle was longer in the newborn period.

Comparison of intravenous nicardipine and nitroglycerin to control systemic hypertension after coronary artery bypass grafting.

The efficacy of intravenous (i.v.) nicardipine hydrochloride (a calcium antagonist) compared with nitroglycerin, the drug generally used for treatment of hypertension after coronary artery bypass grafting, was tested in 20 postoperative patients. The patients were randomly divided in a nonblinded manner into 2 groups. Baseline characteristics were similar in the 2 groups. Patients in both groups received various oral calcium antagonists. In addition, 1 group was treated with i.v. nitroglycerin. Both drugs were infused at a maximal rate of 30 mg/hour, as needed to maintain systolic blood pressure below 110 mm Hg. If blood pressure increased to more than 120 mm Hg, nitroprusside was administered. Intravenous nicardipine was superior to nitroglycerin in control of hypertension after coronary artery bypass grafting. In patients treated with nicardipine, blood pressure was decreased sooner (mean infusion time 7.7 hours vs 11.9 hours for nitroglycerin), mean systolic blood pressure was reduced (94 vs 108 mm Hg for the nitroglycerin group; p less than 0.05), and no patient required nitroprusside treatment (compared with 3 patients who required this treatment in the nitroglycerin group). There were no differences in heart rate, diastolic pressure, cardiac index and urine flow between the 2 treatment groups. No adverse effects were observed in patients treated with nicardipine.

Rupture of the posterior wall of the left ventricle after mitral valve replacement: etiological and technical considerations.

Rupture of the posterior wall of the left ventricle after mitral valve replacement, although infrequent, may be a highly lethal complication. Controversy exists regarding the etiology of this complication. Suggested causative factors include the type and extent of the valvular disease, type and size of the prosthesis, and the surgical techniques used. Our experience over a 20-year period includes 10 patients with rupture of the left ventricle following mitral valve replacement. In all patients, both mitral leaflets were excised together with the attached chordae. Three patients survived after repair of the rupture. Repair consisted of compressing the area between the left atrium and the base of the papillary muscle using two strips of Teflon and deep mattress sutures passed beneath the coronary vessels in the atrioventricular groove. Since 1983 we have routinely preserved the posterior leaflet of the mitral valve with its attached chordae to maintain a "tethered loop" between the mitral valve and ventricle. No further ruptures have occurred. The technique used for repair represents reconstitution of the divided loop between the ventricle and the mitral valve.

Avoidance of blood transfusion in coronary artery surgery: a trial of hydroxyethyl starch.

Banked blood transfusion, with its attendant hazards, may be avoided in certain instances. A search for an acceptable plasma substitute was made. A randomized prospective trial of hydroxyethyl starch (HES) versus plasma for postoperative volume replacement is described. Ninety patients undergoing operations for coronary artery disease were studied over a six-month period. Ten received banked blood in the immediate postoperative period and were excluded from the study. The remaining 80 were randomized into two groups. Group 1 received plasma, and Group 2 received HES. All patients initially had autologous blood transfusion, and in 7 patients this sufficed; these patients were excluded from the study except for regression analysis. Postoperative blood loss and urine output did not differ between groups, but Group 2 patients required significantly more volume replacement (p less than 0.02). In a total of 27 patients drawn from both groups, coagulation factors and colloid osmotic pressure were investigated. There were no significant differences in fibrinogen titer and prothrombin time between groups, but return to normal values was significantly delayed in the HES group (p less than 0.01). Activated clotting time and partial thromboplastin time were unaffected. Colloid osmotic pressure was significantly higher at one week in the HES group (p less than 0.001) and was correlated with the volume of HES given (r = 0.525; p less than 0.01). There were no untoward effects attributable to HES. It is concluded that HES is a safe, cheap, and effective plasma substitute for volume replacement following cardiac surgical procedures.

Sleeve lobectomy (lobectomy and bronchoplasty) for bronchial carcinoma.

We present a series of 90 patients who underwent sleeve lobectomy for malignant bronchial tumors at the Brompton Hospital, London, between 1964 and 1974. The operative mortality was low (1%), and technical complications were infrequent. Bronchial stenosis, which occurred in 6% of patients, was due to recurrence of tumor in 4% and cicatrization in 2%. The majority of patients had squamous cell carcinomas of the upper lobe (76/90). In this group, the 5-year survival was 71% when the hilar lymph nodes were clear of tumor at the time of operation and 17% when the hilar lymph nodes were involved. Because these 5-year survival figures suggest that tumor-free survival is not significantly compromised by this conservative approach, we believe that sleeve lobectomy rather than pneumonectomy should be considered the operation of choice for squamous cell carcinomas of the upper lobe orifice involving the main bronchus.

Reduction of complement activation during bypass by prime manipulation.

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.

Experimental ventricular hypertrophy in growing pigs.

An experimental model has been developed in the growing pig to study the pathology of myocardial hypertrophy. Aortopulmonary shunts were created in 4-week-old piglets and the animals were followed-up to 7 months of age. The pulmonary arterial pressure had increased at 4 weeks of shunt function by an average of 118% and the pulmonary blood flow by as much as 63%. In the longest living animal (7 months), the pulmonary arterial pressure and blood flow had increased by 170 and 53%, respectively, in relation to normal findings. The animals were killed at varying intervals and the hearts removed and examined. The weight of the entire hearts and their individual component parts increased significantly when compared with values found for normal postnatal development (P less than 0.001). The percentage increase in the total heart weights increased at all stages of development varying from an initial 109% to 39% at the time of killing. All the other parameters were also significantly greater than the values found for the normals, including the myocardial wall thickness in both ventricles (P less than 0.001). Histology showed changes comparable to gross myocardial wall thickness hypertrophy observed in human congenital anomalities. The method is recommended as a model for further studies on myocardial hypertrophy in growing individuals.

Entrapping of the clotted intra-aortic balloon in the descending aorta.

Percutaneous insertion of a catheter for intra-aortic balloon pumping (IABP) was introduced in 1979 by Bregman and Casarella and has become a popular technique. Rupture of the balloon, allowing clot to form inside it, is rare. When the clot is large, it may cause entrapping of the balloon. This is a potentially dangerous complication of IABP. We are aware of only one case report of this complication, by Aru and co-workers. The entrapping of the balloon in their report occurred at the site of insertion in the femoral artery. We report here a case in which the entrapping occurred in the descending aorta, and its removal required extensive exposure of the aortic bifurcation.

Complement activation before, during and 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.

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.

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)

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.

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.

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.

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.

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.

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.