Detection of U wave activity in healthy volunteers by high-resolution magnetocardiography.

INTRODUCTION: The purpose of our study was to prove the existence of the U wave using magnetocardiograms (MCGs). METHODS: The 31-channel MCGs of 25 healthy volunteers were recorded. The onset of the U wave was defined by newly developed spatial correlation analysis; and the end, by different approaches. RESULTS: A U wave could be proved in all volunteers. In 10 volunteers (heart rate, 57 +/- 19 beats/min) in whom the U wave was found to be separated from the following P wave, the U wave's end could be determined as a threshold value (U wave duration, 310 +/- 24 milliseconds). In 15 volunteers (heart rate, 70 +/- 38 beats/min), the end of the U waves was concealed by a continuous transition of the U waves into the following P waves. CONCLUSIONS: The U wave seems to be a regular phenomenon and has a distinct spatiotemporal assembly.

Experimental evaluation of the JenaClip transcatheter aortic valve.

OBJECTIVE: Transcatheter techniques of aortic valve replacement are a treatment option for valvular heart disease in high-risk surgical candidates. We evaluated a self-expanding valve system with a novel mechanism of fixation in an experimental setting in an acute animal model and ex vivo in aortic root specimens. METHOD: A self-expanding nitinol stent containing a pericardial tissue valve was implanted in a transapical approach in 15 sheeps. The valve was introduced under fluoroscopic guidance through a 22F sheath by means of a specially designed delivery catheter. Deployment was performed on the beating heart without cardiopulmonary bypass or rapid ventricular pacing and facilitated by positioning feelers anchoring the device to the native aortic cusps. To investigate release and anchoring of the device during retrograde implantation, the stent was also implanted in aortic root specimens obtained from an autopsy series. RESULTS: In animal experiments, stent deployment was primarily successful in 12 (80%) animals. Positioning feelers facilitated implantation by confirming the correct implantation plane of the stent and anchoring to the native aortic cusps. If primary location was not satisfactory the stent was retracted into the catheter and repositioned. After successful implantation no significant changes of hemodynamics were observed. Two animals (13%) developed ventricular fibrillation early in this experimental series due to displacement of one positioning element into a coronary ostium, major regurgitation was observed in two animals. Ex vivo evaluation of the device in aortic root specimens proved feasibility of stent release and leaflet fixation; ex vivo implantation was successful in all cases. CONCLUSION: In this study, we demonstrate feasibility of a leaflet-fixation device in nondiseased aortic valves. The JenaClip provides an effective concept of fixation with positioning feelers that allows exact positioning without outflow obstruction and anchoring the valve to the native leaflets. Further studies are necessary to investigate this concept in diseased aortic valves.

Providing macro- and microcirculatory support with the Lifebridge System during high-risk PCI in cardiogenic shock.

High-risk percutaneous procedures are necessary in patients with contraindications to surgery in whom the inherent risk of the underlying disease is very high. Circulatory support may be provided with an intra-aortic balloon pump. If active cardiac support is required different devices have been successfully used. We report the case of a 75-year-old patient admitted in cardiogenic shock with a severe coronary three-vessel disease with distal left main stenosis. The ejection fraction was 23%. The high-risk PCI of the distal left main coronary artery and left circumflex artery PCI as the main supplying vessel was supported by Lifebridge (Lifebridge Medizintechnik GmbH, Ampfing, Germany), a new portable mechanical circulatory support system. During the procedure we evaluated the macro- and microcirculation. The complex procedure succeeded with a flow of 2-2.5l providing both adequate macro- and microcirculation.

Evaluation of the microcirculation during extracorporeal membrane-oxygenation.

Extracorporeal membrane oxygenation (ECMO) provides pulmonary and circulatory support in critically ill patients (Cardiopulmonary Resuscitation, Acute Respiratory Distress Syndrome, or low output syndrome). Hemodynamic parameters are used for evaluation of the macrocirculation, while the microcirculation is monitored by blood-lactate as a surrogate parameter. We evaluated the microcirculation by orthogonal polarization spectral imaging in a patient during ECMO support. This method was initially proposed to quantify changes of microcirculation in patients with septic shock. However, we were able to non-invasively monitor microcirculatory changes at the bedside during temporary intentional arrest of ECMO due to an exchange of the oxygenator. Using a computerized analyzation model, the flow after ECMO stop in vessels (10-100 microm) in the sublingual mucosa was acutely absent or intermittent, respectively. 120 s after restart, microflow was improved with new ECMO settings compared to baseline, while macrocirculation with a mean arterial pressure of 75 mmHg was present after 60 s. The application of orthogonal polarization spectral imaging might be a valuable technique for evaluation of the microcirculation during extracorporeal circulation. It is rapidly implementable, can be used in vivo, and no invasive probes are required.

Better outcome after cardiopulmonary resuscitation using percutaneous emergency circulatory support in non-coronary patients compared to those with myocardial infarction.

BACKGROUND & OBJECTIVES: Mobile heart-lung-machines applied by percutaneous cannulation are mostly used in patients suffering from acute myocardial infarction (AMI). Whether patients with non-coronary reasons for circulatory arrest benefit of percutaneous emergency circulatory support (PECS) in the same way is still unclear. METHODS: We included 22 consecutive patients who were treated by PECS during a registry period of two years. Primary study endpoint was 30-day mortality rate. RESULTS: Circulatory arrest was caused by AMI in 14 patients (64%). The remaining 8 patients suffered from cardiomyopathy/myocarditis, 4; pulmonary embolism, 2; acute pulmonary failure, 1; and tumor lysis syndrome, 1. Revascularization rate was 93% in the AMI group under PECS support. Overall survival rate was 36.4% at one month: it reached 62.5% among non-coronary patients, but only 21.4% in the AMI group (P = 0.02). Weaning was possible by direct heart transplantation in two patients. Additional two patients required implantation of a left ventricular assist device. Pumpless extracorporeal lung assist was used in one case. CONCLUSION: In this small retrospective study percutaneous emergency circulatory support provided sufficient hemodynamic stabilization in emergency situations. One fifth of AMI patients were saved by immediate restoration of circulation and causal treatment when other means of resuscitation failed. Higher survival rates were noted in non-coronary patients.

Magnetocardiography based spatiotemporal correlation analysis is superior to conventional ECG analysis for identifying myocardial injury.

Electrocardiogram (ECG) particular from tiny, non Q-wave myocardial infarction may lack striking infarct pattern. Spatiotemporal correlation analysis (SCA) of multichannel magnetocardiogram (MCG) is a high-resolution "magnifying glass" to analyze homogeneity of repolarization. SCA involves full 4D spatiotemporal information to identify abnormalities as empirically done by eye in conventional ECG-but on an advanced level of analysis. We compared the discriminatory performance of SCA to ECG analysis in identifying myocardial infarction. Eleven SCA parameters were taken from signal averaged 31-channel MCG and compared to infarct indicators of ECG's in 178 subjects: 108 patients (76 males, mean age 62 years) after myocardial infarction (16-64 d) and 70 controls (36 males, mean age 46 years). SCA improves the detection of myocardial injury: in 72.5% ECG (sensitivity 68.6%, specificity 56%) and in 80.2% SCA parameters (sensitivity 72.6%, specificity 64%) separated patients from controls. SCA is applicable for the analysis of de- and repolarization of cardiac mapping data.

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.