[Acute coronary syndrome : Prevention]. / Akutes Koronarsyndrom : Prävention.

For life style modifications primary and secondary prevention of acute coronary syndrome (ACS) are approximately similar, even though in the postinfarction situation functional diagnostic programs have to be performed in a rehabilitative manner. All three life style pillars of fitness, nutrition and relaxation implicate prognostic significance and the efficacy is higher for secondary prevention than for primary. The pharmacotherapeutic indications for thrombocyte aggregation inhibition are connected to the presence of atherosclerosis and statin medication is already connected to cardiovascular risk factor stratification, for which scores are used. Depending on the postinfarction myocardial destruction after ACS, additional pharmacotherapies, such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor antagonists, beta blockers and also mineral corticoid receptor antagonists are evident. New potential for prevention is ascribed to the new oral anticoagulants (NOAC) in the context of coincidental atrial fibrillation.

[Prevention after acute coronary syndrome]. / Prävention nach akutem Koronarsyndrom.

Mortality is increased in acute coronary syndrome (ACS) related to the extent of myocardial injury even if percutaneous coronary intervention (PCI) was successful. The development of congestive heart failure (CHF) after PCI in ACS is of prognostic interest. Non-invasive imaging plays a major role for determination of structural myocardial damage and loss of function. Secondary prevention regarding pharmacologic and non-pharmacologic therapy is dependent on myocardial function and the presence or absence of CHF. Exercise training as part of the non-pharmacological therapy plays an important role in rehabilitation after ACS according to the severity of injury.

Area at risk and viability after myocardial ischemia and reperfusion can be determined by contrast-enhanced cardiac magnetic resonance imaging.

BACKGROUND/AIMS: Clinical differentiation between infarcted and viable myocardium in the ischemic area at risk is controversial. We investigated the potential of contrast-enhanced cardiac magnetic resonance imaging (ceCMRI) in determining the area at risk 24 h after ischemia. METHODS: Myocardial ischemia was induced by percutaneous coronary intervention of the left anterior descending coronary artery in pigs. Coronary occlusion time was 30 min in group A, which caused little myocardial infarction and 45 min in group B, which led to irreversible damage. 24 h after reperfusion ceCMRI was performed at 2 and 15 min after administration of gadolinium-diethylenetriamine pentaacetic acid. The area at risk was determined by intravenous injection of Evans blue and myocardial viability by triphenyltetrazolium-chloride staining. RESULTS: The signal-intense areas at 2 and 15 min after contrast administration matched the area at risk in groups A and B. Nonviable myocardium in group A was overestimated (14-15%) while good agreement was present in group B. CONCLUSION: The area at risk of reperfused ischemic myocardium can be determined by ceCMRI 24 h after coronary recanalization. This type of information might have relevant clinical implications in the treatment and stratification of patients with acute coronary syndrome in particular after surgical interventions.

[Contribution of early systole to total antegrade flow volume in breath-hold phase-contrast flow measurements]. / Anteil des frühen systolischen Flussanstiegs am antegrad fliessenden Gesamtvolumen bei Phasenkontrast-Flussmessungen in Atemanhaltetechnik.

PURPOSE: To evaluate the contribution of early systole for the assessment of antegrade aortic flow volume by breath-hold velocity-encoded magnetic resonance (MR) flow measurements. MATERIALS AND METHODS: Expiratory breath-hold fast low-angle shot (FLASH) phase-contrast flow measurements (temporal resolution tRes 61 msec, shared phases) perpendicular to the proximal ascending aorta and short axis true fast imaging with steady-state precession (TrueFISP) cine MR ventriculometry (tRes 34.5 msec) were performed in ten healthy male volunteers on a 1.5 T MR system (Sonata, Siemens Medical Solutions). Antegrade aortic flow volume (AFV) and left ventricular stroke volume (LV-SV) were evaluated using Argus Ventricular Function and Argus Flow Software, version MR 2002B (Siemens Medical Solutions). A beta release of Argus Flow MR 2004A allowed interpolation of the flow up-slope during early systole to the preceding R-wave trigger. The respective intraindividual median differences between the AFV of each flow evaluation and LV-SV as well as between both AFV measurements were calculated and compared using the sign test for paired samples. RESULTS: Non-interpolated AFV significantly deviated from LV-SV (p = 0.006), underestimating the latter by 13.1 mL (13 %). Interpolating aortic flow during early systole significantly increased AFV by 10.8 mL (13 %) compared to the flow evaluation which did not take early systole into account (p = 0.006). AFV with interpolation of early systolic flow agreed well with LV-SV (median difference - 3.0 mL or - 3 %, respectively), and no significant difference between these measurements was found (p = 1.0). CONCLUSION: Flow during early systole contributes substantially to total forward flow volume in the ascending aorta. Interpolation of the early systolic up-slope is therefore recommended for the evaluation of breath-hold phase-contrast flow measurements.

Effect of different operative techniques for myocardial revascularisation on hemodynamics and myocardial perfusion in a porcine model.

BACKGROUND: During surgical coronary revascularisation hemodynamics and myocardial contractility can be affected. This in vivo study aimed to determine the effects of different operative techniques on hemodynamics and regional myocardial perfusion. METHODS: In 24 pigs IMA to LAD bypass was constructed using ECC (n = 8) and cardioplegic arrest, OPCAB techniques (n = 8), or the Impella elect 100 support device (n = 8). 8 animals received a sham operation. Mean arterial pressure (MAP), cardiac output (CO), and left ventricular pressure (LVP, LVdp/dt) were recorded. Regional myocardial perfusion (RMP) of both ventricles was assessed by fluorescent microspheres. RESULTS: MAP significantly decreased during revascularisation in all groups ( p < 0.05), staying below preoperative values thereafter ( p < 0.05). After ECC norepinephrine was administered to maintain MAP. CO and LVdp/dt were impaired more distinctly during OPCAB than with Impella ( p < 0.05) during subsequent recovery. RMP showed global reactive hyperemia during early reperfusion after ECC, remained unchanged in OPCAB, and showed low flow during and after Impella pump run ( p < 0.05). CONCLUSIONS: ECC led to hemodynamic impairment with post-ischemic reactive hyperemia. OPCAB created hemodynamic depression but left RMP unchanged. Hemodynamic depression can be reduced by the Impella pump, however regional myocardial blood flow is decreased.

[Non-invasive assessment of coronary artery bypass grafts -- an update]. / Koronare Bypassdiagnostik mit CT und MRT -- eine Bestandsaufnahme.

The limited lifetime and the correlation between graft occlusion and recurring symptoms underline the need for repeated imaging of coronary artery bypass grafts. CT and MRI allow for non-invasive imaging of coronary bypasses with high accuracies concerning the patency of these vessels. Multidetector CT seems to be the CT technique of choice, especially after the introduction of 16 slice CT scanners for morphologic assessment of coronary artery bypass grafts. Compared with MRI, CT is a robust technique for assessment of cardiac anastomoses, native coronary arteries, and for the detection of graft stenoses. MRI, however, is able to deliver functional information about the grafts and the recipient coronary arteries by determining the coronary flow reserve. Furthermore, it can be integrated in a multiparametric MR examination protocol. The follow-up of asymptomatic patients can primarily be done by these non-invasive techniques as nearly every third patient reveals an asymptomatic bypass occlusion 5 years after operation. Furthermore, patients with atypical complaints after the operation may undergo non-invasive imaging as long as documented patency of the bypass averts coronary angiography. Patients with recurrent angina pectoris and/or myocardial ischemia discovered by other cardiologic tests have to undergo coronary angiography.

[Cardio-MRT. The multimodal functional analysis of the future]. / Kardio-MRT. Die multimodale Funktionsanalyse der Zukunft.

Since initial reports in the early 1990s cardiac magnetic resonance imaging (CMR) has matured and is likely to become an established method for routine cardiac diagnostics. The development of faster gradient-echo sequences and stronger magnetic fields has led to improved temporal and spatial resolution. Myocardial viability can be examined by morphological and functional analysis. Contrast enhanced MRI (ceMRI), perfusion measurements and regional wall motion analysis are the major diagnostic tools. The ability to image in arbitrary double oblique planes provides comprehensive visualization of the heart. The introduction of the MR navigator technique allowed for free-breathing motion corrected 3D coronary MR angiography with improved spatial resolution. Using this approach proximal and mid parts of the coronary arteries have been visualized. Subsequently, sensitivity and specificity for the detection of significant coronary stenoses has been evaluated in a multicenter trial demonstrating good sensitivity and specificity for the detection of significant left main and three vessel disease. However, specificity for the detection of single vessel disease was relatively low. Improved motion compensation techniques and novel imaging sequences (SSFP) are currently under investigation to further refine this technique. Despite these promising results coronary MR-angiography is not likely to replace conventional coronary angiography especially with regard to in-plane spatial resolution, coronary collateralization and in-stent restenosis. In contrast, coronary MR-angiography can provide useful morphological informations including functional analysis of the coronary vascular bed. The combination of a conventional cathlab with CMR may provide CMR-guided myocardial interventions. With further improvements in the catheter technology, CMR interventions using real-time imaging guidance will allow to take advantage of the excellent soft tissue contrast of CMR and the simultaneous visualization of the pulmonary, aortic and coronary vessels. CMR is advantageous for screening and follow-up examinations, and it offers comprehensive assessment of cardiac morphology and function in one single examination.

Late improvement of regional wall motion after the subacute phase of myocardial infarction treated by acute PTCA in a 6-month follow-up.

BACKGROUND: The aim of this follow-up study was to investigate the late effects of acute coronary angioplasty (PTCA) on regional wall motion after the subacute phase of myocardial infarction (MI). METHODS AND RESULTS: Seventeen patients were investigated initially at a median of 11 days and again at 6 months after acute PTCA for myocardial infarction (< 8 hours after onset of symptoms) by cardiac magnetic resonance imaging. Corresponding short-axis slices encompassing the left ventricle (LV) were acquired using a standard cine MR for regional wall motion analysis and using delayed contrast enhanced magnetic resonance imaging (ceMRI) for infarct size quantification. The infarct size was similar in the subacute phase and the 6 month follow-up (20.8 and 21.9%, respectively; n.s.). Regional wall motion improved significantly in the area of hyperenhancement [percentage wall thickening (PWT) 21.9% and 37.9%, p < 0.05] in contrast to remote normal myocardium (46.4% and 38.4%; n.s.). Regional wall motion was significantly poorer in transmural compared with nontransmural MI in the subacute stage, and a late improvement could only be observed in transmural MI. CONCLUSION: Transmural areas of hyperenhancement displayed significant late long-term improvement of regional wall motion after acute PTCA, possibly related to prolonged stunning compared with nontransmural areas.

[Evaluation of myocardial perfusion reserve in patients with CAD using contrast-enhanced MRI: a comparison between semiquantitative and quantitative methods]. / Bestimmung der myokardialen Perfusionsreserve bei KHK-Patienten mit der kontrastmittelverstärkten MRT: Ein Vergleich zwischen semiquantitativer und quantitativer Auswertung.

OBJECTIVE: Comparison between two semiquantitative methods and a quantitative evaluation of myocardial blood flow (MBF) for assessment of myocardial perfusion reserve (MPR) in patients with CAD. MATERIAL AND METHODS: 9 patients with coronary stenoses > 50 % were examined with an ECG-gated Saturation Recovery Turbo FLASH sequence by using Gd-DTPA as contrast agent (CA). The entive measurements were performed both during rest and hyperemia induced by adenosine. The up-slopes of the signal-time S(t) curves in the myocardium and left ventricular (LV) cavity were evaluated by a linear fit. MPR was calculated from the original up-slopes of the myocardial S(t) curves and from the up-slopes, which were normalized to the up-slopes of the LV S(t) curves, respectively. For quantification of MBF values, the mathematical model MMID 4 was used and MPR was evaluated from the MBF values. RESULTS: With all tested methods, MPR was reduced in myocardial regions subtended by arteries with stenoses >/= 70 % compared with remote regions. With MMID 4 and the normalized up-slope method, differences between severe ischemic and remote regions were statistically significant. CONCLUSION: The up-slope method with normalization and quantification with MMID 4 are more sensitive methods to differentiate between remote and ischemic myocardium than the up-slope method without normalization.

Application of C1-esterase inhibitor during reperfusion of ischemic myocardium: dose-related beneficial versus detrimental effects.

BACKGROUND: Complement activation during reperfusion of ischemic myocardium augments myocardial injury, and complement inhibition with C1-esterase inhibitor (C1-INH) at the time of reperfusion exerts marked cardioprotective effects in experimental studies. Application of C1-INH in newborns, however, was recently reported to have dangerous and even lethal side effects. This study addresses the essential role of dosage in studies using C1-INH. METHODS AND RESULTS: Cardioprotection by C1-INH was examined in a pig model with 60 minutes of coronary occlusion followed by 120 minutes of reperfusion. C1-INH was administered intravenously 5 to 10 minutes before coronary reperfusion without heparin at a dose of 40, 100, and 200 IU/kg body wt. Compared with the NaCl controls, C1-INH 40 IU/kg reduced myocardial injury (44.1+/-13.8% versus 76.7+/-4.6% necrosis of area at risk, P/=100 IU/kg) of C1-INH will provoke detrimental side effects, probably via its procoagulatory action.

Plasma protein loss during surgery: beneficial effects of albumin substitution.

Plasma protein loss during abdominal surgery is a known phenomenon, but its possible pathophysiological relevance has remained unknown. The present study evaluates the effects of albumin substitution on systemic and local hemodynamics and cellular interactions in the mesenteric microcirculation. Rats underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Plasma protein concentrations, systemic and local hemodynamics were recorded during the follow up period, with or without albumin substitution. Depending on the time course of plasma protein loss in control experiments, 80% of the calculated protein loss was infused during the first 2 h of surgery, and the other 20% over the following 5 h of intravital microscopy. The control group received a continuous infusion of normal saline. Plasma protein loss was mainly due to loss of albumin. A significant increase in adherent and rolling leukocytes was observed during the course of mesenteric exteriorization, which was almost entirely reversed by albumin replacement. Albumin substitution led to stabilisation of mean arterial pressure and abdominal blood flow and also attenuated reductions in arterial base excess. Albumin infusions to replace plasma protein loss may be a simple and effective measure to attenuate microcirculatory disturbances and may be of benefit in patients undergoing abdominal surgery.

Effect of the atrial blanking time on the detection of atrial fibrillation in dual chamber pacing.

Patients with paroxysmal atrial fibrillation (PAF) and dual chamber pacemakers frequently have short postventricular atrial blanking times and sensitive atrial sensing thresholds used to provide reliable detection and mode switching during AF. However, short atrial blanking times increase the risk of atrial sensing of ventricular far-field signals. We evaluated if the length of the atrial blanking time influences the detection of AF. The study included ten patients with a VDDR (n = 7) or DDDR system (n = 3), who presented with AF at 18 follow-up visits. Bipolar atrial sensing was programmed to the most sensitive value. Atrial blanking times were programmed from 100 to 200 ms in 25-ms steps in each patient. Using marker annotation, the following parameters were measured at ten consecutive ventricular beats: VAF = the interval between ventricular stimulus and first sensing of AF; AFS = the number of atrial-sensed events between two ventricular events; and XAF = the interpolated number of atrial-sensed events during atrial blanking time. The intervals between ventricular events and between atrial-sensed event markers showed no significant differences for the five blanking times tested. There was no significant influence of the atrial blanking time onto the measured parameters (least square means +/- standard error) with VAF between 281 +/- 12 and 300 +/- 12 ms (P = NS), AFs between 3.4 +/- 0.2 and 3.6 +/- 0.2 beats (P = NS) and XAF between 1.84 +/- 0.12 and 2.03 +/- 0.12 beats (P = NS). At ventricular rates < 100/min, the atrial sensing of AF in dual chamber pacemakers demonstrated no evidence for deterioration by an increase of the atrial blanking time from 100 to 200 ms. Thus, the risk of ventricular far-field sensing may be reduced without compromising atrial sensing.

[Perfusion MR imaging of the heart with TrueFISP]. / MR-Perfusionsbildgebung des Herzens mit TrueFISP.

OBJECTIVE: Development and test of a saturation-recovery TrueFISP (SR-Trufi) pulse sequence for myocardial perfusion MR imaging (MRI) using improved gradient hardware. MATERIAL AND METHODS: Measurements were performed on a 1.5 T scanner with prototype gradients (50 mT/m, minimum rise time 300 microseconds). T1-weighted first-pass MRI of Gd-DTPA (0.025 mumol/kg) kinetics in the myocardium was performed using an SR-Trufi pulse sequence (TR/TE/alpha = 2.6 ms/1.4 ms/55 degrees) with a saturation preparation of TD = 30 ms before the TrueFISP readout. Measurements were performed in volunteers (n = 4) and in a pig model of chronic ischemia (n = 1). RESULTS: In phantoms, the signal intensity was linear with contrast concentration up to 0.9 mmol/kg Gd-DTPA. MR images obtained with SR-Trufi had a good image quality and high spatial resolution of 2.1 mm x 2.1 mm. Differences of the contrast agent's kinetics between a subendocardial perfusion deficit and neighboring myocardium were well visible on both MR images and signal-time curves derived from the region-of-interest analysis. CONCLUSION: SR-Trufi appears to be an interesting new technique for the assessment of myocardial microcirculation using dedicated cardiovascular MR systems.

[MR angiography and flow measurement in coronary arteries and coronary bypass grafts]. / MR-Angiographie und Flussmessung in Koronararterien und koronaren Bypassgefässen.

Better MR image quality of coronary arteries and coronary grafts is the product of increased spatial and temporal resolution. Breathing artifacts could be reduced by implementing breath-holding and navigator techniques. With these developments normal coronary arteries can often be imaged reliably. Several trials have been performed in order to test the reliability of MR angiography to detect coronary artery stenosis. But up to now, sensitivity and specificity have proven to be too low to introduce these techniques in clinical routine. The patency of coronary grafts can be detected reliably using different MR techniques. Coronary flow reserve can be measured using the MR phase contrast technique. This noninvasive approach was tested in diseased coronary arteries and in graft stenoses. A reduced MR coronary flow reserve corresponded to reduced flow reserve measured invasively. Measurement of MR flow reserve in normal and diseased coronary grafts revealed significant differences (3.3 +/- 0.4 vs. 1.3 +/- 0.2).

C1-esterase-inhibitor treatment at early reperfusion of hemorrhagic shock reduces mesentry leukocyte adhesion and rolling.

OBJECTIVE: Complement activation probably plays a pathogenic role in multiple organ failure in shock. This study evaluates the effects of C1-esterase-inhibitor treatment on leukocyte-endothelial interaction in the mesenteric microcirculation in hemorrhagic shock. METHODS: Rats underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Volume controlled hemorrhagic shock was provoked by arterial blood withdrawal (2.5 mL/100 g body wt. for 60 minutes) followed by a 4-hour reperfusion period. C1-INH (100 IU/kg body wt. i.v.) or 0.9% NaCl i.v. were administered as a bolus at the beginning of reperfusion. Reperfusion time mimicked a "pre-hospital" phase of 30 minutes followed by a quasi "in-hospital" phase of 3.5 hours. The "in-hospital" phase was initiated by substitution of blood followed by fluid resuscitation with normal saline. RESULTS: Application of C1-INH markedly reduced rolling and adherent leukocytes to numbers approaching baseline values. Vmax and shear rate of the mesenteric microcirculation improved in both groups after reperfusion with a trend to higher values in the C1-INH group (n.s. p = 0.08). CONCLUSION: C1-INH applied in a bolus dose of 100 IU/kg body wt. i.v. abrogated enhanced leukocyte adhesion and rolling in the mesenteric microcirculation after hemorrhagic shock. Single bolus treatment with a complement inhibitor may provide clinical benefit when applied at an early stage of reperfusion during hemorrhagic shock.

Plastic foil technique attenuates inflammation in mesenteric intravital microscopy.

BACKGROUND: Interpretation of intravital microscopic observations is complicated by the "inflammatory"-type response to the trauma inflicted on the tissue by the surgical preparation. The present study evaluates different experimental conditions for prolonged observations of the mesenteric microcirculation in the rat. METHODS: The mesentery was exteriorized through a median laparotomy and subjected to an organ bath or a modified plastic foil technique. Hemodynamic, metabolic, respiratory, and microcirculatory data were analyzed. RESULTS: In contrast to the plastic foil technique, which yielded stable baseline values over a 5-h observation period, venular velocity and wall shear rates decreased significantly in the organ bath technique, and leukocyte adhesion to the endothelium was significantly increased. Likewise, abdominal blood flow decreased significantly by 35% and base excess declined (-10.0+/-0.4 mmol/L) in the organ bath, with reduced pco(2) (26.4+/-2.5 mm Hg vs. 33.7+/-1.1 mm Hg in plastic foil technique) due to respiratory pH compensation. CONCLUSIONS: The plastic foil technique was found clearly superior to the organ bath technique for maintenance of stable baseline metabolic, hemodynamic, and microcirculatory conditions in mesenteric intravital microscopy.

C1-esterase inhibitor reduces infarct volume after cortical vein occlusion.

In order to clarify the role of complement as a mediator of cerebral infarct growth, we inhibited the classical complement activation pathway in a photochemical cortical vein occlusion model. Immediately after occlusion, rats were infused with either 0.9% saline (vehicle), or C1-esterase inhibitor (C1-INH) over 30 min. Regional cerebral blood flow (rCBF) decreased after occlusion, and was about 50% of baseline after 2 h. No difference was noted between experimental groups. Mean arterial blood pressure (MABP) and arterial blood gases were likewise unaffected by the treatment. However, administration of C1-INH had significantly reduced infarct volume by 72%, as evaluated after 5 days survival. Thus, the neuroprotective effect cannot be explained by an improvement of cerebral perfusion but rather by protection of the parenchyma in the penumbra.

Surgical procedure affects physiological parameters in rat myocardial ischemia: need for mechanical ventilation.

Several surgical approaches are being used to induce myocardial ischemia in rats. The present study investigated two different operative procedures in spontaneously breathing and mechanically ventilated rats under sham conditions. A snare around the left coronary artery (LCA) was achieved without occlusion. Left lateral thoracotomy was performed in spontaneously breathing and mechanically ventilated rats (tidal volume 8 ml/kg) with a respiratory rate of 90 strokes/min at different levels of O2 supplementation (room air and 30, 40, and 90% O2). All animals were observed for 60 min after thoracotomy. Rats operated with exteriorization of the heart through left lateral thoracotomy while breathing spontaneously developed severe hypoxia and hypercapnia despite an intrathoracic operation time of <1 min. Arterial O2 content decreased from 18.7 +/- 0.5 to 3.3 +/- 0.9 vol%. Lactate increased from 1.2 +/- 0.1 to 5.2 +/- 0.3 mmol/l. Significant signs of ischemia were seen in the electrocardiogram up to 60 min. Mechanically ventilated animals exhibited a spectrum ranging from hypoxia (room air) to hyperoxia (90% O2). In order not to jeopardize findings in experimental myocardial ischemia-reperfusion injury models, stable physiological parameters can be achieved in mechanically ventilated rats at an O2 application of 30-40% at 90 strokes/min.