Mechanische Herz-Kreislauf-Unterstützung in der Kardiologie

[Importance of mechanical assist devices in acute circulatory arrest]

Mechanical assist devices are indicated for hemodynamic stabilization in acute circulatory arrest if conventional means of cardiopulmonary resuscitation are unable to re-establish adequate organ perfusion. Their temporary use facilitates further diagnostic and therapeutic options in selected patients, e.g. coronary angiography followed by revascularization.External thorax compression devices allow sufficient cardiac massage in case of preclinical or in-hospital circulatory arrest, especially under complex transfer conditions. These devices perform standardized thorax compressions at a rate of 80-100 per minute. Invasive mechanical support devices are used in the catheter laboratory or in the intensive care unit. Axial turbine pumps, e.g. the Impella, continuously pump blood from the left ventricle into the aortic root. The Impella can also provide right ventricle support by pumping blood from the vena cava into the pulmonary artery. So-called emergency systems or ECMO devices consist of a centrifugal pump and a membrane oxygenator allowing complete takeover of cardiac and pulmonary functions. Withdrawing blood from the right atrium and vena cava, oxygenated blood is returned to the abdominal aorta. Isolated centrifugal pumps provide left heart support without an oxygenator after transseptal insertion of a venous cannula into the left atrium.Mechanical assist devices are indicated for acute organ protection and hemodynamic stabilization for diagnostic and therapeutic measures as well as bridge to myocardial recovery. Future technical developments and better insights into the pathophysiology of mechanical circulatory support will broaden the spectrum of indications of such devices in acute circulatory arrest.

Preoperative Insertion of an Intra-Aortic Balloon Pump Improved the Prognosis of High-Risk Patients Undergoing Off-Pump Coronary Artery Bypass Grafting

This study investigated the efficacy and safety of preoperative insertion of an intra-aortic balloon pump (IABP) in high-risk coronary atherosclerotic disease patients undergoing off-pump coronary artery bypass grafting (OPCAB). A total of 232 patients were recruited to the study, of whom 107 underwent percutaneous insertion of an IABP prior to OPCAB. The remaining 125 patients underwent OPCAB alone. Pre-, peri- and postoperative parameters were compared between the two groups. Preoperative insertion of an IABP was associated with a shorter stay in intensive care, decreased incidence of postoperative dialysis and acute heart failure, and a reduction in postoperative mortality compared with OPCAB alone. There were no between-group differences in terms of haematocrit level, number of distal anastomoses, volume of postoperative drainage or incidence of reoperation for bleeding and postoperative stroke/cerebrovascular accident. In conclusion, preoperative insertion of an IABP improved the prognosis of high-risk CAD patients undergoing OPCAB.

Superior venous drainage in the "LifeBox": a portable extracorporeal oxygenator with a self-expanding venous cannula

BACKGROUND

In an experimental setting, the performance of the LifeBox, a new portable extracorporeal membrane oxygenator (ECMO) system suitable for patient transport, is presented. Standard rectilinear percutaneous cannulae are normally employed for this purpose, but have limited flow and pressure delivery due to their rigid structure. Therefore, we aimed to determine the potential for flow increase by using self-expanding venous cannulae.

METHODS

Veno-arterial bypass was established in three pigs (40.6+/-5.1 kg). The venous line of the cardiopulmonary bypass was established by cannulation of the external jugular vein. The arterial side of the circulation was secured by cannulation of the common carotid artery. Two different venous cannulae (SmartCanula 18/36F 430mm and Biomedicus 19F) were examined for their functional integrity when used in conjunction with the centrifugal pump (500-3000 RPM) of the LifeBox system.

RESULTS

At 1500, 2000, 2500, and 3000 RPM, the blood flow increased steadily for each cannula, but remained higher in the self-expanding cannula. That is, the 19F rectilinear cannula achieved a blood flow of 0.93+/-0.14, 1.47+/-0.37, 1.9+/-0.68, and 1.5+/-0.9 l/min, respectively, and the 18/36F self-expanding cannula achieved 1.1+/-0.1, 1.9+/-0.33, 2.8+/-0.39 and 3.66+/-0.52 l/min. However, when tested for venous line pressure, the standard venous cannula achieved -29+/-10.7mmHg while the self-expanding cannula achieved -13.6 +/-4.3mmHg at 1500 RMP. As the RPM increased from 2500 to 3000, the venous line pressure accounted for -141.9+/-20 and -98+/-7.3mmHg for the 19F rectilinear cannula and -30.6+/-6.4 and -45+/-11.6mmHg for the self-expanding cannula.

CONCLUSION

The self-expanding cannula exhibited superior venous drainage ability when compared to the performance of the standard rectilinear cannula with the use of the LifeBox. The flow rate achieved was approximately 40% greater than the standard drainage device, with a maximal pump flow recorded at 4.3l/min.

First use of a novel plug-and-play percutaneous circulatory assist device for high-risk coronary angioplasty

OBJECTIVES

Novel circulatory assist devices provide hemodynamic stability in high risk coronary interventions. They ensure sufficient organ perfusion during transfer in case of procedural failure or cardiogenic arrest. We describe the first human use of a novel plug-and-play circulatory assist device for high risk coronary angioplasty.

METHODS

An 84 year old lady suffered syncope with complex fracture of the left forearm. Her syncope was related to a subtotal stenosis of the left main coronary artery associated with an acute myocardial infarction. Additional risk factors were previous cardiac surgery, pulmonary disease, diabetes mellitus, and renal insufficiency. Coronary angiography revealed stenosis of both coronary ostia. The emergency assist device LIFEBRIDGE was connected with the patient's circulation by percutaneous cannulation (15F and 17F) of the femoral artery and vein.

RESULTS

Stent implantation was performed in both coronary ostia by Judkin's technique. The cannulas were removed two hours after the intervention by local compression. Osteosynthesis of the left radius and ulna was performed five days later under regional anesthesia. The patient was discharged without any complains on day 10.

CONCLUSION

This case illustrates the safe and easy use of a novel plug-and-play percutaneous circulatory assist device for high risk interventions. It may be recommended for use in emergency situations.

[Emergency therapy for acute heart failure]

Acute heart failure (AHF) is defined as the rapid onset of symptoms and signs secondary to abnormal heart function which may occur with or without previous cardiac disease. Diagnosis and classification of severity are primarily based on clinical findings. The conditions leading to and reasons for acute heart failure which require specific therapeutic interventions should always be taken into consideration. Immediate goals in the guideline-oriented treatment of AHF are to improve the patient's symptoms and stabilize the hemodynamic condition. Medical therapy - besides oxygen supply - consists of the application of vasodilators, diuretics, and inotropes (especially dobutamine) depending both on the patient's clinical state and hemodynamic parameters. In the presence of ongoing signs of hypoxia, non-invasive ventilation has to be considered early. Bradycardia in AHF patients should initially be treated with atropine; a temporal pacemaker has to be inserted if no response is achieved by medical therapy. Ventricular fibrillation and tachycardia require immediate cardioversion.