Pulmonary arteriovenous fistula drainage into the left atrium

Arteriovenous fistulas with venous drainage into the left atrium are a rare anomaly. Although the etiology of pulmonary arteriovenous fistulas is unknown, these abnormalities are considered to have occurred during early fetal development. A case of this malformation in a 72-year-old woman successfully treated by surgery is described.

Reduced frequency of occlusion of aorto-pulmonary shunts in infants receiving aspirin

OBJECTIVE

Infants with severely reduced pulmonary perfusion due to complex congenital cardiac malformations are in need of an improved flow of blood to the lungs. One option for treatment is to construct a systemic-to-pulmonary arterial shunt. Although such shunts have been used since 1945, their spontaneous occlusion remains a major problem in the long-term.

DESIGN

We studied all infants in whom a systemic-to-pulmonary arterial shunt had been constructed using a Gore-Tex tube graft between December 1989 and March 1996.

PATIENTS

Of 46 infants undergoing construction of a shunt, 7 (15%) died within 30 days of surgery. The shunts had to be taken down in 2 infants. Thus, 37 infants were included in the study. All but three infants received Aspirin. Aspirin was discontinued on the personal decision of individual physicians. Of 22 infants, 3 never received Aspirin, and in 19 it was stopped well before undertaking subsequent surgery. Aspirin was administered continuously to 15 infants until further surgery.

RESULTS

Those in whom Aspirin was discontinued, or not given, and those receiving Aspirin until further surgery, were comparable concerning their age, time of follow-up, severity of the cardiac lesions, and size and type of shunt. Partial or complete occlusion of the shunt occurred in 2 of 15 (13%) infants taking Aspirin, but was seen in 12 of 22 (54%) infants in whom Aspirin was discontinued. Of these, 3 died due to acute occlusion of the shunt.

CONCLUSIONS

Aspirin reduced effectively the rate of occlusion of systemic-to-pulmonary arterial shunts, and should be continued as long as the shunt is in place.

Fatal pulmonary embolism after atrial septal defect closure in a paediatric patient

A four-year-old girl died of massive acute bilateral pulmonary embolism 11 days after direct closure of a secundum atrial septal defect (ASD II), despite postoperative anticoagulation until the patient was ambulatory. An autopsy showed thrombotic deposits on the suture line of the ASD closure, bilateral 90% occlusion of the pulmonary arteries, and haemorrhagic ulcerative ischaemic colitis of the descending colon and the sigmoid.

Chest re-exploration for complications after lung surgery

BACKGROUND

Review of the most recent chest re-explorations for lung surgery complications may show methods by which risks can effectively be reduced.

METHODS

The data on rethoracotomies following lung surgery over the past 14 years in our department were retrospectively reviewed. The indication, the type of operation, the outcome, and various factors influencing the postoperative mortality were analyzed. From 1983 to 1996, 1960 patients underwent primary thoracotomies for various lung diseases. Among these, 73 (3.7%) patients required re-exploration for various postoperative complications.

RESULTS

Mean age was 56.8 years (15-80 years). There were 66 (90.4%) men and 7 (9.6%) women. The most common indication for rethoracotomy was hemorrhage in 38 (52%) patients. The source of bleeding was a mediastinal and/or bronchial blood vessel in 8 patients and an intercostal blood vessel in 6 patients. Six patients had to be reoperated because of hemorrhage from a major artery of the hilus. In 14 cases the postoperative hemothorax occurred without evident surgical origin. Further indications for rethoracotomy were bronchopleural fistula (BPF) in 13 (17.8%) patients, and persistent parenchymal leak in 8 (10.9%) patients. There were 8 additional causes distributed among the remaining 14 (19.3%) patients. The overall mortality rate was 17.8% (13/73), with the highest (38.4%) among BPF patients.

CONCLUSIONS

Postoperative complications following lung surgery which require rethoracotomy are rare. The most common complication is postoperative bleeding. This is followed by bronchial stump insufficiency which is associated with the highest mortality and morbidity. Our experience shows that the need for re-exploration can hardly be reduced but the indication for re-exploration should be established as early as possible to avoid late complications.

[Pathogenesis of venous congestion symptoms after Fontan operation]

To evaluate a possible common pathogenetic denominator, we compared hemodynamic data of 18 patients who had an uneventful long-term course after a Fontan procedure, with the respective data of patients who developed symptoms of central venous congestion either in the immediate postoperative period (n = 10) or during late follow-up (n = 6). We found a coincidence of increased early postoperative venous pressures (CVP; 17.1 +/- 2.9 mm Hg) with relatively high cardiac indices (3.6 +/- 0.6 l/min.m-2) as compared to 2.4 l/min.m-2 in the group of patients with a symptom-free long-term course but no significant difference in total pulmonary resistance between the two groups. The increased CVP (17.2 +/- 2.9 mm Hg) in patients with late chronic central venous congestion is primarily due to increased total pulmonary resistance (552 +/- 131 dyn s/cm5.m-2). Both groups of patients with central venous congestion display a ratio of systemic to total pulmonary resistance lower than 4.5 whereas symptom-free patients have a significantly higher resistance ratio (6.8 +/- 2.3) and a highly significant increase in peripheral resistance to values of 2687 +/- 527 dyn s/cm5.m-2 as compared to 1486 +/- 340 dyn s/cm5.m-2 in the early postoperative group. Correspondingly, mean arterial pressure of the symptom-free patients is significantly elevated (93 +/- 11 mm Hg) as compared to a control group (81 +/- 11 mm Hg). Based on our theory an increase in systemic arterial resistance may lead to a fall in mean capillary filtration pressure and therefore counteract central venous congestion. To support this, we briefly present cases where pharmacologic enhancement of systemic arterial resistance was effective in the treatment of venous congestion whereas pharmacologic lowering of systemic resistance induced venous congestion.

[Anesthesiologic aspects of pregnancy and delivery in a patient following a modified Fontan procedure ]

The number of patients with congenital cyanotic heart disease who reach child-bearing age is increasing. This is partly a consequence of the high long-term survival and the haemodynamic benefits resulting from the Fontan procedure, which is used for the definitive palliation of such cyanotic heart disease as tricuspid atresia and single ventricle. However, so far little experience has been recorded with pregnant patients who have undergone right ventricular exclusion procedures. The particular physiology of a univentricular heart and a passive, non-pulsatile blood flow through the lungs has significant implications for the anaesthetic obstetric management of these patients. We report a case of successful pregnancy and caesarean delivery after a modified Fontan procedure. CASE REPORT. The patient was a 30-year-old pregnant woman with a singleton pregnancy. At the age of 20, after four palliative shunt operations, she had undergone a modified Fontan operation due to tricuspid atresia with a single ventricle, d-transposition of the great arteries, pulmonary atresia and a single atrium. Following the Fontan repair, she initially suffered from intermittent Wolff-Parkinson-White syndrome and isorhythmic AV dissociation. The pregnancy was uneventful, and caesarean section was scheduled for 32 weeks' gestation. Because of the increased risk of thrombosis, the patient was treated with s.c. heparin preoperatively; for this reason, epidural anaesthesia was excluded, though it may otherwise be preferred for such patients. Amoxicilline was used to prevent endocarditis. At the date of caesarean delivery her body weight was 54 kg and boy height, 155 cm. Before induction of anaesthesia, a central venous and a radial artery catheter were placed for invasive pressure monitoring. An exaggerated left lateral tilt position was used to avoid aortocaval compression. After careful preoxygenation, anaesthesia was induced with 24 mg etomidate, 1.5 mg norcuronium, and 75 mg succinylcholine. Halothane 0.5-0.7% in oxygen was used during the first few minutes of surgery. Central venous pressure under mechanical ventilation was 20 mmHg, while the heart rate varied between 70 and 90 bpm. Delivery was accomplished 8 min after the induction of anaesthesia. The Apgar scores after 1 and 5 min were 9 and 10, respectively. Anaesthesia was continued with fentanyl, midazolam and nitrous oxide 50%. The remainder of surgery was unevenful. The child is now 5 years old and healthy. The mother has a near-normal activity level and does not need any help to care for her child. DISCUSSION. After a modified Fontan repair, i.e. atriopulmonary or total cavopulmonary anastomosis, the pulsatile pulmonary blood flow is converted to a passive, non-pulsatile blood flow that depends critically both on the pressure gradient between right (RAP) and left atrial pressure (LAP) and on pulmonary vascular resistance (PVR). Thus, the maintenance of an adequate transpulmonary pressure gradient and avoidance of an increase in PVR are of major importance for the obstetric anaesthetic management in patients who have undergone right ventricular exclusion procedures. Impairment of venous return caused by slight caval compression or high airway pressure may reduce cardiac output more critically than in patients with a normal circulation. CONCLUSION. This case demonstrates that the haemodynamic consequences of pregnancy and of caesarean delivery under general anaesthesia can be tolerated in post-Fontan patients despite the absence of a contractile pulmonary ventricle.

Clinical outcome and echocardiographic findings of native and prosthetic valve endocarditis in the 1990's

Prosthetic valve endocarditis is considered to be associated with a more severe prognosis than native valve endocarditis. Among other factors, inappropriate visualization of vegetations in prosthetic valve endocarditis by transthoracic echocardiography is responsible for this observation. Since the introduction of transoesophageal echocardiography into clinical practice the diagnostic sensitivity and specificity of the detection of vegetations located on prosthetic valves have been enhanced. Therefore we aimed to determine and compare the prognosis of prosthetic valve endocarditis and native valve endocarditis in the era of this improved diagnostic approach. One hundred and six episodes of infective endocarditis in 104 patients were seen at our institution between 1989 and 1993. Eighty patients (77%) had native valve endocarditis and 24 (23%) had late prosthetic valve endocarditis. In the latter group two patients had recurrent infective endocarditis. Patients with prosthetic valve endocarditis were older (mean age 64 vs 54 years in native valve endocarditis; P < 0.001) and the majority was female (62% vs 38% in native valve endocarditis; P < 0.05). In prosthetic valve endocarditis, infection of a valve in the mitral position predominated (65% vs 30% in native valve endocarditis; P < 0.01), whereas in native valve endocarditis more than half the cases had isolated aortic valve endocarditis (51% vs 27% in prosthetic valve endocarditis; P < 0.01). In prosthetic valve endocarditis more cases were caused by Staphylococcus aureus (31% vs 14% in native valve endocarditis; P = 0.08), whereas in native valve endocarditis the most frequent organisms were streptococci (29% vs 19% in prosthetic valve endocarditis; P = 0.12). Differences in the clinical features of native valve endocarditis and prosthetic valve endocarditis could not be found except for a higher rate of embolism in native valve endocarditis (40% vs 19% in prosthetic valve endocarditis; P < 0.05). Vegetations could be detected by transthoracic echocardiography more frequently in native valve endocarditis (71% vs 15% in prosthetic valve endocarditis; P < 0.0001). Transoesophageal echocardiography visualized vegetations in 95% of the episodes of native valve endocarditis and in 80% of the episodes of prosthetic valve endocarditis (P = 0.09). Thus, the diagnostic gain by transoesophageal echocardiography was greatest in prosthetic valve endocarditis. Patients with native valve endocarditis had significantly larger vegetations than patients with prosthetic valve endocarditis (P < 0.05 for length, P < 0.001 for width). The median time to diagnosis was similar in native valve endocarditis and prosthetic valve endocarditis (31 vs 28 days). Surgery was performed in 74% of patients with native valve endocarditis and in 58% of those with prosthetic valve endocarditis; the median time delay between the diagnosis of infective endocarditis and surgery tended to be shorter in prosthetic valve endocarditis than in native valve endocarditis (45 vs 60 days). The in-hospital mortality and the mortality during a follow-up of 22 +/- 10 months did not significantly differ between native valve endocarditis and prosthetic valve endocarditis (21% vs 17%; 28% vs 25%). In summary in the era of transoesophageal echocardiography, late prosthetic valve endocarditis does not seem to carry a worse prognosis than native valve endocarditis. This can be attributed in part to the improved diagnostic accuracy achieved by transoesophageal echocardiography leading to comparable diagnostic latency periods in both patient groups. Finally, better characterization of vegetations on prosthetic valves by transoesophageal echocardiography allows early lifesaving surgery in patients with prosthetic valve endocarditis.

Infective endocarditis in the elderly in the era of transesophageal echocardiography: clinical features and prognosis compared with younger patients

PURPOSE

Advanced age is considered to be associated with a more severe prognosis in infective endocarditis (IE), which is relevance in view of a change in epidemiology of the disease with an increasing proportion of elderly people. We wanted to examine whether in the era of improved diagnostic sensitivity for IE by transesophageal echocardiography the clinical course in elderly persons would be still more severe than in younger patients.

PATIENTS

During the period from 1989 to 1993, 104 patients with 106 episodes of IE were treated at our university hospital. Three groups were compared: group A with 28 patients younger than 50 years, group B with 58 patients aged 50 to 70, and group C with 20 patients older than 70. Transesophageal echocardiography was performed in 78% of the patients; it was not performed in 22% of the patients with a conclusive transthoracic examination. The patients were followed up for an average of 25 months after the diagnosis.

RESULTS

No significant differences were observed among the age groups with respect to the possible source of infection, the frequency of positive blood cultures, and the type of infective organisms. Elderly patients more often had predisposing valvular conditions (eg, degenerative and calcified lesions and prosthetic valves), which decreased the sensitivity of transthoracic echocardiography to 45% as compared with 75% in group A. Transesophageal echocardiography improved the diagnostic yield by 45% in group C and by 47% in group B. Vegetations were smaller in group C and B as compared with group A, whereas other echocardiographic characteristics were similar. Fever and leukocytosis were less frequent in group C (55% and 25%, respectively) than in group A (82% and 61%, respectively). The interval between the onset of symptoms and the diagnosis of IE was similar in all groups. Elderly patients underwent surgical therapy as frequently (65%) as the other groups. The 1-year survival in group C (26%) was comparable with that in group A (22%) and group B (22%). The major determinant of survival was the occurrence of embolic complications.

CONCLUSION

Infective endocarditis in elderly patients caused less severe clinical symptoms than in young patients. The early diagnosis in elderly patients was facilitated by the high sensitivity of transesophageal echocardiography, which enabled the timely initiation of an appropriate medical and surgical therapy. This led to a clinical outcome similar to that for younger patients.

[Normal pregnancy duration after maternal Fontan operation of univentricular heart]

Up to now pregnancy in patients with a previous Fontan operation for definitive palliation of a univentricular heart has been regarded as contraindicated. Two cases of a pregnancy after Fontan operation and univentricular heart were published in the literature. In a single case a successful delivery of the fetus could be achieved. The presented case is the third published pregnancy after Fontal operation and the second with a successful fetal outcome. The 30 years old patient was born with a univentricular heart of right ventricular type with tricuspid and pulmonary atresia and persisting arterial duct. After bilateral Blalock Taussig anastomoses (1966) and modified Waterston-Cooley-anastomosis (1974) a primary existing cyanosis could be improved. The cyanosis was completely abolished after definitive repair with the Fontan operation at the age of 17 (1980). The course of pregnancy and its surveillance is reported. In the 32nd week of gestation cesarean section had to be performed because of threatening cava compression. A healthy female fetus of 1275 g was delivered. The mother's postoperative recovery was uneventful. Meanwhile the neonate and the mother have been discharged and are in good clinical condition.

[Effects of age in the correction of isthmus stenosis on postoperative stiffness of the aorta]

Operative surgery for coarctation aims to eliminate the narrowed segment of the aorta and to restore a normal function of the aortic Windkessel, which depends on normal elastic properties of the aorta. To evaluate the effect of age at coarctectomy on the postoperative aortic elasticity, parameters of regional wall stiffness within the aortic arch were determined in 24 children after coarctectomy by means of echocardiography and blood pressure measurements. Actual data were compared with reference data (mean value normalized to body weight: mn +/- SD) obtained from n = 43 children, adolescents and young adults (age 1 month to 28 years; mean 12.6 years): elastic modulus Epn = 0.20 +/- 0.07 Mdyn/cm2/kg0.11; stiffness index beta = 3.45 +/- 1.3; diameter Dn = 0.52 +/- 0.08 cm/kg0.37. The results revealed that 4.9 years (mean) after coarctation repair within the first year of life (mean 3.2 months, n = 10) the parameters of elasticity and the diameter did not differ from normal. In those n = 5 children operated on in the age of 4.7 years there was a tendency towards increased aortic stiffness and reduced diameter 8.9 years later. In n = 9 children with a mean age of 9.2 years at operation the elastic modulus was increased 7.6 years later: Epn = 0.28 +/- 0.11 Mdyn/cm2/kg0.11; (p < 0.01). The diameter of the proximal aortic arch was significantly reduced (DN =0.42 +/- 0.08 cm/kg0.37., P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Application of a transpulmonary double indicator dilution method for postoperative assessment of cardiac index, pulmonary vascular resistance index, and extravascular lung water in children undergoing total cavo-pulmonary anastomosis: preliminary results in six patients

Total cavo-pulmonary anastomosis (TCPA) is used for the functional correction of an increasing spectrum of congenital heart diseases. The passive pulmonary perfusion after surgical exclusion of the right ventricle has significant implications for the postoperative hemodynamic management of these patients. Because conventional pulmonary artery thermodilution catheters present methodologic problems in patients after TCPA, important cardiovascular variables such as cardiac index (CI) and pulmonary and systemic vascular resistance indices (PVRI, SVRI) usually cannot be assessed directly. In a preliminary series of six patients undergoing TCPA (age 6-22 years), the applicability of a transpulmonary double indicator dilution technique for postoperative determinations of CI, PVRI, SVRI, and extravascular lung water (EVLW) was investigated. After central venous injection of ice-cold indocyanine green (5 mg), thermal and dye dilution curves were recorded in the abdominal aorta using a combined 4F fiberoptic thermistor catheter. Qualitative assessment of the tracer curves did not show major differences in measurements in patients with pulsatile perfusion of the lungs. CI, SVRI, and EVLW could be determined by use of standard algorithms. Pulmonary perfusion pressure for the calculation of PVRI was based on the gradient between central venous and left atrial pressure. The quality of indicator dilution curves allowed determination of flow-related variables in 33 of a total of 34 sets of measurements. No catheter-related problems occurred during or after the period of investigation. Postoperative EVLW was within the range that is commonly accepted as normal for adults. Mean PVRI initially decreased during the postoperative course but showed a significant increase after extubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Three decades of follow-up of aortic and pulmonary vascular lesions in the Williams-Beuren syndrome

The diagnostic criteria of the Williams-Beuren syndrome (WBS) were established almost 3 decades ago. Until now there has been little knowledge about the natural and post-surgical history of vascular lesions in this syndrome. In order to evaluate the long term follow-up of aortic and pulmonary vascular lesions, we have analysed the catheterization data, angiocardiograms, and Doppler-echo measurements in 59 patients who were seen at least twice in our institution between 1961 and 1993. Their follow-up periods ranged from 2.1 to 28.2 years. Of 45 patients with supravalvular aortic stenosis (SVAS) with a mean follow-up period of 12.9 years, it became evident that pressure gradients of less than 20 mm Hg in infancy generally remained unchanged during the first two decades of life. Pressure gradients exceeding 20 mm Hg increased from an average of 35.5 mm Hg to 52.7 mm Hg in 13 patients. Of these, 8 required surgical relief of the narrowing. In 7 patients aortic hypoplasia was documented. In 5 of them the caliber of the aorta showed a tendency towards normalisation within a period of 11.9 to 23.9 years. Of 6 individuals with aortic hypoplasia and surgical relief of SVAS, 4 patients developed restenosis at the distal end of the aortoplasty patch. In contrast, 9 patients with operated SVAS-but without aortic hypoplasia-remained free of restenosis over a period of 11 years (mean). Coarctation occurred in 4/59 patients; restenosis was seen in 2 after 5 and 16 years. Peripheral pulmonary stenosis was followed in 23 patients over 14.4 years (mean).(ABSTRACT TRUNCATED AT 250 WORDS)

[Quantification of postoperative pulmonary valve insufficiency: severity and clinical symptoms]

Surgical treatment of pulmonary stenosis may lead to inevitable valvular incompetence. The hemodynamic and clinical significance of post-operative pulmonary insufficiency (PI) is uncertain. In patients presenting cardiomegaly and reduced exercise tolerance reoperation may be considered. However, pulmonary valve replacement remains controversial. In order to elucidate the relevance of PI in the long-term post-operative course, quantitative data of PI were compared with chest radiographs and the physical condition. Thirty-one patients with a mean age of 18.5 years (3-36 years) were studied. Twenty-two patients had surgical correction of Tetralogy of Fallot (TOF) and nine had commissurotomy of pulmonary valve stenosis (PS). Catheterization was performed, on average, 12.9 years (2-29 years) after operation in 68% of cases with an interval of more than 10 years. PI was quantitated by digital roentgen densitometry. Regurgitant fraction (RGF) ranged between 13-61%, according to a right ventricle volume load index (VBI) of 1.15-2.6 (ratio of total to effective stroke volume). Twenty of 31 patients (12 TOF, 8 PS) had PI as the only significant lesion. VBI (1.15-2.6) correlated with the cardio thoracic ratio (0.50-0.64), r = 0.74. All patients were in good physical condition. 11 actively took part in sports: all of the eight patients studied by ergometry met normal conditions. Four patients had antiarrhythmic medication. Eleven of 31 patients had PI and additional abnormalities: tricuspid insufficiency (4), right ventricular pressure overload (5), ventricular septal defect (1), depressed left ventricular function (5), and aortic insufficiency (3).(ABSTRACT TRUNCATED AT 250 WORDS)

Successful surgical management of left ventricular free wall rupture in the course of myocardial infarction

The case of a 49-year-old patient is described who presented with cardiogenic shock and electrocardiographic signs of an inferolateral Q-wave infarction, and who received systemic lysis with anisoylated plasminogen streptokinase activator complex (Eminase). After coronary angiography had revealed only peripheral occlusion of a posterolateral branch of the left circumflex coronary artery, a pericardial effusion surrounding both right and left ventricular cavity was identified by echocardiography and was successfully drained via an inferior pericardiotomy with an immediate rise of blood pressure. Upon thoracotomy myocardial rupture was detected in the infarct area and was closed with mattress sutures. A total of 39 cases of successful surgical repair of myocardial free wall rupture reported in the literature is discussed. The mean age of patients was 59.6 +/- 1.3 years. Posterior and anterolateral infarctions were the preferred locations of myocardial rupture. Rupture occurred with a mean delay of 5.0 +/- 1.0 days after the onset of clinical infarct signs. Among patients saved by surgical means were 33 males and 6 females.

[Right-left shunt caused by myxoma of the right atrium]

We report on a 62-year-old female patient who developed central cyanosis due to a right atrial myxoma with right-to-left shunt.

Will emergency coronary bypass grafting after failed elective percutaneous transluminal coronary angioplasty prevent myocardial infarction?

An emergency aorto-coronary bypass grafting operation was performed within 12 hours after the development of acute myocardial ischemia due to partial or complete vascular occlusion in 34 of 950 (3.6%) patients who had received elective percutaneous transluminal coronary angioplasty (PTCA). Of the 34 patients, three (= 8.8%) died postoperatively in irreversible cardiogenic shock. Half of the surviving patients developed a Q-wave infarction after the operation, whereas the other half remained without transmural infarct. With comparable clinical data and times of operation up to placement of the aorto-coronary bypass vessel, an adequate residual perfusion must still have been present in the cases with non Q-wave infarction. Since in many cases a myocardial necrosis is unavoidable despite relatively early operative revascularization, the decisive role will be played by the remaining perfusion of the vessel concerned and any collaterals. It follows that treatment of an early PTCA complication, occurring in the catheter laboratory, ought to be the earliest possible aorto-coronary bypass operation unless available cardiological methods can reliably assure reperfusion. Treatment of a PTCA complication occurring later, however, e.g. after hours in the intensive-care unit, should be a repeat PTCA attempt: surgery at this stage will not prevent the transmural infarction but will increase risk of lethal complications.

[Use of the autoperfusion catheter in acute coronary occlusion within the scope of percutaneous transluminal coronary angioplasty (PTCA)]

The procedure of an autoperfusion catheterization after acute coronary occlusion by dissection during percutaneous transluminal coronary angioplasty (PTCA) is described. Multiple side holes proximal and distal to the dissection allow passive myocardial perfusion only by systemic blood pressure. In the case presented, the catheter immediately reestablished coronary blood flow and thereby produced resolution of symptoms and myocardial ischemia. This easy procedure made it possible to perform the subsequent coronary bypass operation as a controlled revascularization and it prevented myocardial necrosis.

[Experiences with telemetry-supported pacemaker controls in patients with VVI pacemakers]

Investigations on telemetry-supported pacemaker control were carried out in 55 patients with the VVI-pacemaker Quantum (Intermedics). The investigations were done at least once during the 6-24 month period after implantation. The telemetry function was utilised for pacemaker programming, for clarifying pacemaker defects and for characterising the type of pacemaker electrode used. It could be shown that the Osypka spiral electrode VY (Dr. Osypka) had a lower impedance, and greater pulse width and charge threshold in comparison with the two other electrodes used (Encor, Cordis; Polyflex, Intermedics). In 38 of the 55 patients (69%) a pulse amplitude of 2.7 V could be chosen, whereas an amplitude of 5.4 V was programmed in the rest. Pacemaker sensing threshold was set to values between 2.4 and 3.0 mV. Pacemaker problems appeared in three patients; in one patient due to programming too economically and in the other two due to pacemaker defects.

Fontan procedure--indication and clinical results

Twenty-six patients with tricuspid atresia (15), univentricular heart (7), and single ventricle (4) underwent 27 Fontan or modified Fontan procedures between 1975 and 1981. The age of the patients varied between 4 and 26 years. Twenty patients had had a total of 33 palliative operations prior to correction. The original Fontan procedure was performed in 10 patients from 1975 to 1977. According to the various anatomical findings modifications of the Fontan procedure, such as direct anastomosis or implantation of a valveless conduit, were introduced in 1977. Early mortality among all the patients was 22% (6 patients died). Three deaths occurred in the initial period 1975 to 1977. Among the last 20 patients (1978 to 1981) there were 3 early deaths. Three patients with single ventricle survived, one died due to pulmonary failure. There were 2 late deaths (sepsis, sudden cardiac death). Postoperative cardiac catheterization performed in 17 patients revealed excellent results in 13 patients; the remaining 4 displayed diminished arterial oxygen saturation, three of them had Glenn palliation prior to corrective surgery. Postoperative right atrial mean pressure varied from 10 to 23 mmHg. The left ventricular parameters were within the normal range.

Hemodynamics and energy balance of the left ventricle during low flow venoarterial bypass and venoarterial counterpulsation with an oxygenator in experimental animals

The effects of partial venoarterial continuous flow and counterpulsating bypass with an oxygenator on the hemodynamics and energy balance of the left ventricle were studied in 8 anesthetized closed-chest dogs. A mean blood flow of 35%, and 48% of the animals's cardiac output was pumped via an extracorporeal circuit. 1. with continuous flow by means of a roller pump, and 2. with ECG-synchronized counterpulsation by means of a one-chambered electropneumatically driven ventricle pump. Central venous shunt blood was oxygenated with a double oxygenator and returned into the descending aorta. A bypass of 48% of cardiac output both with continuous and counter-pulsating flow resulted in a significant decrease of the maximal rise in left ventricular pressure (dp/dt max, 32% and 30% respectively) and of the calculated myocardial oxygen requirement (10% and 16% respectively). The improved myocardial energy balance during diastolic counterpulsation was due to a significant decrease in systolic aortic pressure (11%). During bypass of 35% of cardiac output with continuous flow the hemodynamics and energy balance of the left ventricle remained essentially unchanged. However, during bypass with counterpulsating flow a significant decrease in systolic pressure (7%) dp/dt max. (19%), and myocardial requirement oxidend (9%) was obtained. The results indicate that, if combined with counterpulsation, partial venoarterial bypass of only 35% of cardiac output can be an effective method of supporting the failing heart. Low flow venoarterial counterpulsation may therefore be of value for transitory use up to 72 hours in postoperative low-output syndrome or myocardial infarction whenever intraaortic balloon pumping alone is not sufficient or combined right and left heart failure is present.

Early and long-term results after surgical treatment of abdominal aortic aneurysm

From 1959 to July 1981, 121 patients underwent surgery for abdominal aortic aneurysm. One hundred-nine patients were male and 12 female. Ninety-one patients had an elective operation, 30 patients were operated on an emergency basis. Among the electively treated there were 32 asymptomatic patients. Early mortality of electively operated patients was 13.2% in period I (1959 to 1974), and 8.8% in period II (1975 to 1981). The early death rate of asymptomatic patients decreased from 9.4% to 4.8%. The prognosis of emergency patients remained unchanged: 50% died in both periods. Cardiac complications were the major cause of early death. The late complication rate related to the aneurysmectomy was 18.1%. Four patients died of rupture of the proximal anastomosis. Aneurysm-related reoperations were necessary in 19.1% of the patients. The mortality rate for patients under 65 years was 6.1% in period II, and 16.7% in patients over 70 years. Another severe risk factor is coronary artery disease (16.0% mortality in period II), especially in combination with advanced age (21.4% mortality in period II). The results indicate that the abdominal aortic aneurysm should be treated electively; however, poor risk patients should not undergo surgery if the aneurysm is asymptomatic. In younger patients with coronary artery disease, coronary artery bypass surgery should be considered prior to aneurysmectomy.