E. Merikallio

ASD in patients over 40 years of age.

To evaluate the benefits of operative treatment of congenital heart disease in older age groups, a clinical study on patients over 40 years of age with atrial septal defect was carried out. The series consisted of 125 consecutive patients operated on between 1966 and 1974. There were 8 cases with a primum, 12 cases with a sinus venosus type of secundum and 105 cases with a simple secundum defect. The operative mortality was 2 patients (1.6%). It was due to myocardial infarction in one case and high pulmonary vascular resistance in the other. On re-examination 3-6 months postoperatively, 107 patients were improved, 13 patients unchanged and 3 patients were worse than before operation. On re-evaluation after an average period of 6 years, 88 patients were still improved. 32 patients unchanged and 3 patients were worse compared with their pre-operative status. On the basis of the results and the previous reports on atrial septal defect without operation, the surgical correction of ASD even in older age groups can be recommended. The problem of deterioration of some patients, despite a good immediate postoperative result, is discussed.

Cardiorespiratory function after correction of tetralogy of Fallot. Modifying effect of previous shunt operation.

Of 28 patients with total surgical correction of tetralogy of Fallot in adult life, 22 had previously undergone Blalock-Taussig shunt operation. Possible modifying effects of the shunt on pulmonary ventilation and perfusion and on exercise tolerance were investigated with spirometry, radiospirometry and bicycle ergometry. The observed ventilatory volumes and capacities and diffusing capacity were significantly lower than the predicted values. Vital capacity was significantly reduced in patients with adverse NYHA or haemodynamic classification. Between the various NYHA or haemodynamic groups no statistically significant difference was demonstrable in pulmonary function or diffusing capacity or in airway resistance. Ventilatory obstruction was found also in patients without previous shunt. Other lung function tests showed no significant difference between the shunt and the non-shunt group. Nor was distribution of lung perfusion significantly affected by shunt. No correlation was seen between lung function and bicycle ergometric findings. However, in non-shunt patients who had ventilatory obstruction or impaired diffusing capacity, exercise tolerance was significantly higher than in patients who had had palliative shunt.

Cardiac Tamponade and Different Modes of Artifical Ventilation

Cardiac tamponade after open‐heart surgery often occurs in a situation when the patient is still mechanically ventilated and needs circulatory support with catecholamines. To evaluate the effects of different modes of artificial ventilation and dopamine on cardiac tamponade, an experimental study was carried out in seven mongrel dogs. In pentobarbital ‐ N2O anaesthesia, a cardiac tamponade of 20 mmHg was produced by injecting 120–200 ml of normothermic saline into the pericardium. Intermittent positive pressure ventilation (IPPV) and positive end‐expiratory pressure (PEEP) ventilation with frequencies of 12 and 20 were tested before and after producing the tamponade. Cardiac tamponade produced a significant fall in arterial pressure and cardiac output, a significant rise in central venous pressure and only a slight increase in pulmonary arterial pressure. PEEP with the slower ventilation frequency of 12 produced additional, significant falls in cardiac output and systemic arterial pressure, which were not noted with the ventilation frequency of 20 and PEEP. Dopamine infusion increased the cardiac output by increasing the heart rate during tamponade. It is concluded that PEEP ventilation with a slow frequency should not be used if cardiac tamponade is suspected after open‐heart surgery, and that dopamine has a favourable effect on haemodynamics even in the presence of a severe cardiac tamponade.

Prostacyclin production in free versus native IMA grafts

The long-term patency of the internal mammary artery (IMA) in coronary artery surgery has been superior to that of other grafts. We tested the IMAs as free grafts in an experimental study with 8 dogs. The right IMA was dissected free as a naked artery without surrounding tissue, and the left IMA was dissected with surrounding tissue using electrocautery. Both free IMA grafts were anastomosed first to the left IMA one after another and then to the left anterior descending coronary artery. The grafts were harvested 6 months later, and the prostacyclin (PGI2) production of the free IMA grafts and of the intact IMAs was measured. Radioimmunoassay was used to measure 6-keto-prostaglandin F1 alpha, the stable metabolite of PGI2. The PGI2 production of the right free IMA without surrounding tissue was 21.1 +/- 8.5 pg/mg and of the left IMA with surrounding tissue was 17.9 +/- 7.9 pg/mg (expressed in picograms of 6-keto-prostaglandin F1 alpha per milligram of tissue wet weight). The control value of the intact IMA was 18.3 +/- 6.5 pg/mg. Thus, PGI2 production of both free IMAs did not differ significantly from each other and from controls. This study showed that free IMAs were able to produce as much PGI2 as were control IMAs and that the type of dissection did not affect the result.

Total Correction of Tetralogy of Fallot in Adults

A series of 42 patients who underwent total correction of tetralogy of Fallot as adults is presented. Previous palliative operation had been performed in 33 cases: Blalock-Taussig shunt in 28 (bilateral in 6), Brock operation in four and Potts anastomosis in one case. Severe cyanosis (average hemoglobin 203 g/l), thrombotic complications and hypoxic spells were the most pertinent of the clinical manifestations necessitating the total repair. Blalock-Taussig shunt had closed spontaneously before the intracardiac operation in 14 cases (3 bilateral) and in 11 it was ligated. In six cases the shunt was left untreated, being hemodynamically insignificant at operation. Three of the 42 patients died in association with the intracardiac operation. A-V block developed in two patients and required permanent pacemaker. During follow-up periods of up to 13 years, a residual ventricular septal defect was found in seven patients. Two of the defects were surgically closed. Five were not corrected, as the patients were doing well and the pulmonary/systemic flow ratio was less than 1.5 at repeat catheterization. Two-thirds of the patients were in NYHA class I at re-examination, and the others were in class II. The subjective functional improvement was greater than could have been expected from results of exercise tolerance tests.

Effects of synthetic blood combined with contrast medium on coronary endothelium: an experimental study.

The study described was carried out to evaluate endothelial injury following incubation of coronary material in contrast medium and in contrast medium diluted with fluorocarbon solution. Six porcine hearts were excised and isolated. Immediately thereafter, pieces of the main coronary arteries and ascending aortas were incubated in four different solutions: 1) blood, 2) contrast medium, 3) fluorocarbon solution, 4) fluorocarbon — contrast medium (1:1). Flow surfaces and coronary endothelial morphology were evaluated by scanning electron microscopy (SEM). Porcine blood (at room temperature) preserved endothelial structures intact but, in two samples, small patchy areas of denuded surface were found. Four minutes immersion in contrast medium resulted in easily visible changes in the endothelial lining and individual cells. Denuded flow surface areas were common, the intact surface morphology was flattened. After 7 minutes, destruction was total. The addition of fluorocarbon solution to contrast medium (1:1) diminished the changes, which also occurred later than after incubation in pure contrast medium. After 7 minutes, separate endothelial cells were still identifiable but the microvilli had disappeared. Fluorocarbon solution preserved the endothelial lining well during a 10-minute follow-up period. The experimental protocol described confirmed the deleterious effect of con-trast medium on coronary endothelial lining, which could be reduced to some extent by adding fluorocarbon solution to contrast medium.

Intracellular-type solution flush for preservation of myocardium and coronary and pulmonary artery flow surface

Modified Euro-Collins solution (ECS), which has been successfully used in kidney, liver and lung transplantation, was tested concerning myocardial and endothelial preservation in nine piglets. In six (group I), 1-hour cardiac arrest was induced with cold modified ECS, and in three (group II) heart-lung transplantation was performed, using modified ECS for graft preservation. In group I myocardial energy preservation was determined with biochemical assays for adenosine triphosphate, creatine phosphate, lactate and creatine 5, 15, 30 and 60 minutes after aortic clamping, and preservation of endothelium in the aorta and coronary arteries was studied with scanning electron microscopy. In group II electron microscopy was performed on endothelial samples from the ascending aorta and coronary and pulmonary arteries of the heart-lung block after excision, after 2 hours of ischemia, and after 1-2 hours of reperfusion. High-energy phosphates decreased progressively during the ECS cardioplegia in group I, and circulatory support was required during the post-transplantation reperfusion period in group II. The endothelial lining in all specimens was remarkably well preserved, however. Modified ECS flush thus was ideal for vascular endothelium but, because of its poor energy-preserving capacity, unsuitable for cardioplegia.

The possibility of using celiac trunk branches as coronary artery bypass grafts

The internal mammary artery has proved to be superior to the saphenous vein for coronary artery bypass grafting, because of its arterial nature and closer approximation in size to the coronary arteries. But the internal mammary artery cannot reach the posterior surface of the heart as a pedicled graft. Two suitable intra-abdominal grafts can reach that surface, viz. the right gastroepiploic artery and the splenic artery. In experiments on eight dogs (weight 9-13.5 kg), the gastroepiploic artery was found to be too small for coronary artery anastomosis, and therefore the splenic artery was used. The size approximation with coronary artery (diameter less than 1 mm) was good. Four dogs survived the month of the study. In two of them the anastomosis was patent, in another the splenic artery was patent despite occlusion of the anastomosis, and in the fourth dog both anastomosis and graft were thrombosed. The possibility of using visceral arterial grafts in coronary surgery is discussed.

Free Internal Mammary Artery as Canine Coronary Artery Bypass Graft

From 8 dogs both internal mam mary arteries (IMA) were harvested: the right IMA as a naked artery with out surrounding tissue and the left IMA with 2-cm-wide surrounding tis sue. Both free IMA grafts were anas tomosed to the proximal end of the left IMA one after another and then to the left anterior descending coro nary artery. At six months the free IMA grafts were harvested and stud ied by light microscopy and scanning electron microscopy (SEM). Six dogs lived the period of six months and all free IMA grafts were patent at that time. In the histologic study 3 grafts were graded as normal and intimal thickening was seen in 8 cases. The endothelial cells were covering the lu minal surface of every free IMA graft in SEM, although some degeneration was seen. This study showed that free IMA grafts maintain their patency well and the method of the dissection of the IMAs did not have any effect on the results.

Ischaemic Cardiac Aneurysms and Ventricular Septal Defects: Surgical Treatment with and Without Revascularization

During the period 1968--78, 35 patients with left ventricular aneurysm after acute myocardial infarction were operated on at the Department of Thoracic and Cardiovascular Surgery, University Central Hospital, Helsinki. Twenty patients underwent resection of the left ventricular aneurysm and had coronary bypass grafting (Group I) and 15 patients had aneurysmectomy without revascularization procedures (Group II). Most of the patients (21) had the operation within one year after acute myocardial infarction. The aneurysm was located in the anterior wall in 31 cases and in the posterior wall in 4 cases. Three patients in Group II had a concomitant ventricular septal rupture, which was repaired simultaneously with the aneurysmal resection. In average, the patients in Group I had bypass grafting in 1.8 coronary branches. There were no intra-operative deaths. Three patients in the revascularization group died and 2 patients in the non-revascularization group died during hospitalization (15% hospital mortality). Two patients in the revascularization group and one in the non-revascularization group died during the average follow-up time of 3.4 and 6.4 years for the respective groups (late mortality 10 and 7%). The rest of the patients were doing well, including those with repaired VSDs. Follow-up coronary angiography was carried out of 12 patients; in 10 all the grafts were patent and in 2 one revascularized coronary branch had a patent graft. Revascularization produced apparent relief of anginal symptoms. Its beneficial effects on longevity remained unestablished.