Acute respiratory failure after cardiac surgery: clinical experience with the application of continuous arteriovenous hemofiltration.

Hemodynamic and oxygen measurements were obtained before and during 24 h of continuous arteriovenous hemofiltration (CAVH) in 36 postoperative cardiac surgery patients with severe acute pulmonary failure. During the first 6 h, the low mean arterial pressure averaged only 50 +/- 7 mm Hg; PaO2 was 90 torr on an inspired oxygen fraction of 0.86 +/- 0.03; and lactic acid was 10.5 +/- 6 mmol/L. Of the 34 patients recovering from shock within 12 h, only 24 (67%) were hospital survivors. Cardiac index, oxygen availability index, oxygen consumption, and PaO2 increased during CAVH. This treatment decreased serum levels of the myocardial depressant factor, thus allowing catecholamine support to be reduced. We conclude that CAVH eliminates cardiopulmonary toxic substances partly responsible for shock. Our patients' improved hemodynamic and respiratory function suggests that CAVH may be useful in postoperative cardiac surgery patients with respiratory and hemodynamic failure.

[Positive modification of hemodynamics in post cardiac surgery patients by hemofiltration. Improved method for the demonstration of myocardial depressant factor (MDF) in hemofiltrate]. / Positive Beeinflussung der Hämodynamik bei postkardiochirurgischen Patienten durch die Hämofiltration. Eine verbesserte Methodik zur Darstellung des Myocardial Depressant Factor's (MDF) in Hämofiltrat.

The method of haemofiltration was used in 29 postoperative cardio-surgical patients with low blood pressure, high left ventricular filling pressure and low total peripheral resistance, which did not respond to the use of the intraaortic balloon pump or pharmaco-therapy. In severe low-output syndrome hemodynamic parameters are: reduced mean arterial pressure, increased left ventricular filling pressure, increased mean arterial pulmonary pressure as well as significantly reduced total peripheral resistance [4-6, 28]. Inspite of pharmaco-therapy, cardiac performance regarding peripheral perfusion is insufficient; this leads to a vicious cycle of irreversible O2-debt and severe cellular damage. After haemofiltration there was a significant improvement in the haemodynamic parameters, which in our opinion was due to the elimination of toxic peptides such as Myocardial Depressant Factor (MDF). In 27 of a total of 29 patients, haemodynamic parameters returned to normal after treatment. 19 patients were discharged, eight patients died after a number of days or weeks from causes not related to the original cardiogenic shock (cerebral embolism, reinfarction, myocardiopathy and pneumonia).

[The research programme "Artificial Heart" at the 2nd Department of Surgery, University of Vienna: a ten year review (author's transl)]. / Das Forschungsprojekt "Künstliches Herz" an der II. Chirurgischen Universitätsklinik Wien. Ein 10-Jahres-Bericht.

The experimental and clinical results are presented of the research programme "Artificial Heart" carried out by the 2nd Department of Surgery, University of Vienna. In particular, an assessment of the clinical experience in 177 patients with the intra-aortic balloon pump is documented and it is concluded that only limited cardiac support is possible by this pump. In view of this fact more efficient methods of mechanical circulatory support, such as the interaortic auxilliary ventricle, the aortic "Windkessel" ventricle with guiding balloon, and two types of ventriculo-aortic bypass ventricle were tested with regard to their haemodynamic and long-time efficacy. The transatrio-aortic auxilliary ventricle (E-LVAD) was also clinically tested in 11 patients. In conclusion the problems of total mechanical heart replacement are discussed.

[Partial mechanical cardiac replacement in experimental cardiogenic shock]. / Mechanischer Teilherzersatz beim experimentellen kardiogenen Schock.

The importance to evaluate artificial ventricles for left heart assist under cardiogenic shock conditions is emphasized. The main cardiogenic shock models currently used for assisted circulation research are mentioned. Our own method called selective peripheral coronary embolization is presented in detail with its anatomic, pathologic-histologic and electrocardiographic pattern. Polyester fibrils are embolized selectively to the posterior wall of the heart by direct puncture of the circumflex branch of the left coronary artery. Shock hemodynamics and the effects of circulatory assist by the pneumatically driven ellipsoid ventricle (ELVAD) are demonstrated in 20 acute calf experiments. The artificial ventricle was inserted to the circulation between the natural left ventricle and the thoracic aorta in a paracorporeal and intrathoracic position. ELVAD activation was followed by a significant decrease of left ventricular pressure (-65%) and left atrial pressure (-35%). Cardiac index was increased by 10% and mean aortic pressure by 28% from their shock levels. Hemodynamics in irreversible ventricular fibrillation are analyzed in a calf experiment with a 40 hours survival only with ELVAD assist.

[Exit block: a postoperative complication of pacemaker implantation (author's transl)]. / Der Exit-Block als postoperatives Problem der Schrittmacherchirurgie.

Exit block occurs in 7% of cases following implantation of a pacemaker for the first time and appears to be a serious and unpredictable occurrence which cannot be prevented by the selection of a particular technique or type of electrode of pacemaker. Therapeutic measures in patients who are not dependent on a pacemaker consist primarily of exchanging the intracardial lead. In all patients, as well as in those cases with recurrence of exit block, a pulse width-adjustable pulse generator should be implanted without resorting to other methods of questionable efficacy. The implantation of such a pulse generator was successful in all our cases.

Clinical application of the ellipsoid left heart assist device.

The ellipsoid left heart assist device (E-LVAD) was implanted in eight patients suffering from intraoperative heart failure. It was not possible to remove these patients from extracorporeal circulation following an intracardiac procedure; therefore, implantation of the E-LVAD was performed during extracorporeal circulation. The inflow connector was pushed forward from a purse-string suture on the right superior pulmonary vein, across the mitral valve and into the left ventricle. The outflow connector was joined to the ascending aorta. In two patients, the artificial heart chamber was removed after complete recovery of the circulation; these patients, however, later died. In six other patients, untreatable right heart failure developed and these patients died with the pump in place. It is concluded, therefore, that the right heart must also be mechanically supported during postoperative heart failure.

[Influencing of the kininogen-Kinin-System by means of a kallikrein-inhibitor during extracorporeal circulation in open heart surgery (author's transl)]. / Beeinflussung des Kininogen-Kininsystems durch einen Kallikreinhemmer bei Operationen am offenen Herzen in extracorporaler Zirkulation.

During extracorporeal circulation for open heart surgery an activation of the kininogen-kininsystem occurs with a decrease in plasma-kininogen-levels significantly exceeding the effect of haemodilution, and thus being due to an increased liberation of kinin. This effect could be suppressed by kallikrein inhibition by means of a protease-inhibitor.

Artificial heart driven by an automatic driving system.

Thrombi formation within artificial ventricles is caused by the effects of biomaterials, stagnation areas, and major turbulences. During systolic and diastolic cycles, stagnation area increase in hearts that are properly designed. Stagnation areas may also occur in properly designed artificial hearts that are not working with a maximum stroke volume. The ellipsoid heart avoids stagnation areas and major turbulences because all the inside surfaces have an adequate washout with blood. The optimum washout of these surfaces is obtained by driving the heart with a constant maximum stroke volume. The cardiac output is regulated according to Starling's law by adjusting the frequency according to the venous return.

The Windkesselventricle with guiding balloon as a new approach for assisted circulation.

A simple method was developed to aid the patient with low cardiac output syndrome following cardiac surgery. The concept was shown to be feasible in electric circulatory analog studies and verified in 20 dog experiments. A Dacron graft (end-to-side) through the right second intercostal space connects the ascending aorta to the subcutaneously implanted, ellipsoidal-shaped artifical ventricle. A spherical polyurethane balloon is positioned in the aorta distal to the Dacron graft via the femoral artery. The ventricle and balloon are pneumatically driven synchronously with the ECG. In natural systole the balloon is inflated, occluding the aorta, and the artificial ventricle sucks the entire stroke volume. In natural diastole the balloon deflates and the artificial ventricle ejects the blood into the peripheral arteries. With this system it is possible to maintain a normal systemic pressure and have high hemodynamic efficiency. The left ventricular systolic pressure is 85 percent unloaded. The systolic wave is turned 180 degrees to the natural. After treatment, the device can be removed without thoracotomy.

Saving the aortic and pulmonary artery valves with total heart replacement.

The natural aortic and pulmonary artery valves can be saved with excision of the ventricles and inflow valves. These valves remain functional and unaltered with implantation of an artificial heart, when pumped for 96 and 122 days. The capacity of the artificial heart to meet the physiological needs of the animal, during exercise and body growth, over 3 and 4 mos has been documented. All of the parameters monitored in 2 experiments for 3 mos (and continuing) and 4 mos clearly demonstrates the efficacy of meeting the cardiac needs with an artificial heart.

[Partial replacement of the heart]. / Zum Teilersatz des Herzens

A ventricular-aortic blood pump was constructed for the functional replacement of the left heart. Hemodynamic experiments showed that the device was able to pump the total cardiac output in calves with a body weight under 85 kg. In these cases the myocardial oxygen consumption decreased to 40%. Laboratory findings in 5 longterm experiments revealed a complete adaptation of the body to the artificial organ up to 73 days.

[Long-term results in pacemaker therapy]. / Langzeitergebnis bei der Schrittmachertherapie

The range of age, life expectancy and problems of functional control in pacemaker patients, are reported. The results demonstrate the dependability of pacemaker treatment, provided that there is an adequate functional control. The life expectancy, in comparison with total population, was found to be similar.