Markus Kunze

Electrocardiographic and cardiac magnetic resonance imaging parameters as predictors of a worse outcome in patients with idiopathic dilated cardiomyopathy

Aims Clinical parameters are weak predictors of outcome in patients with idiopathic dilated cardiomyopathy (IDC). We assessed the prognostic value of cardiac magnetic resonance (CMR) parameters in addition to conventional clinical and electrocardiographic characteristics. Methods and results One hundred and forty-one IDC patients were studied. QRS and QTc intervals were measured in 12-lead surface electrocardiogram. Patients were followed for median 1339 days, including 483 patient-years. The primary endpoint—cardiac death or sudden death—occurred in 25 (18%) patients, including 16 patients with cardiac death, 3 patients with sudden cardiac death (SCD), and 6 patients with ICD shock. Late gadolinium enhancement (LGE) was detected in 36 patients (26%). Kaplan–Meier survival analysis displayed QRS >110 ms (P = 0.010), the presence of LGE (P = 0.037), and diabetes mellitus (P < 0.001) as significant parameters for a worse outcome. Multivariable analysis revealed cardiac index (P < 0.001), right ventricular end-diastolic volume index (RVEDVI) (P = 0.006) derived from CMR imaging, the presence of diabetes mellitus (P = 0.006), and QRS >110 ms (P = 0.045) as significant predictors for the primary endpoint. Conclusion Cardiac index and RVEDVI derived from CMR imaging in addition to QRS duration >110 ms from conventional surface ECG and diabetes mellitus provide prognostic impact for cardiac death and SCD in patients with IDC.

Assessment of Left Ventricular Outflow Tract Geometry in Non-Stenotic and Stenotic Aortic Valves by Cardiovascular Magnetic Resonance

PURPOSE To assess the geometry and area of the left ventricular outflow tract (LVOT) in non-stenotic and stenotic aortic valves and to determine the aortic valve area (AVA) in non-stenotic valves by magnetic resonance imaging (MRI) using a modified continuity equation. METHODS Twenty patients (10 male, mean age 54.8 +/- 15 years) without known aortic valve disease and 10 patients (7 male, mean age 65.1 +/- 14 years) with moderate to severe aortic stenosis were included in this study. MRI was performed using a 1.5 T scanner (Philips Intera CV). AVA was assessed by planimetry on high quality SSFP cine sequences and used as reference standard. LVOT area was defined by calculating a circular area using the LVOT diameter from the 3 chamber view (3CV) and by planimetry. Peak flow velocity was assessed in the LVOT and the proximal aorta. AVA was calculated by a modified Gorlin equation, the continuity equation and a modified continuity equation using the planimetric LVOT area. RESULTS Planimetric AVA ranged from 2.9 to 6.4 cm2 in patients with non-stenotic and from 0.3 to 1.3 cm2 with stenotic valves, LVOT area from 3.4 to 6.1 cm2 and from 2.6 to 6.5 cm2, respectively. The LVOT area based on the LVOT diameter derived from the 3CV was significantly underestimated in comparison to planimetry in non-stenotic and stenotic aortic valves (3.3 +/- 0.7 vs. 4.7 +/- 1.0 cm2, p < 0.0001; mean difference 1.1 +/- 0.12 cm2, CI 0.86-1.36 and 3.7 +/- 1.2 vs. 4.7 +/- 1.5 cm2, p < 0.05; mean difference 1.0 +/- 1.0 cm2, CI 0.24-1.71). The Gorlin formula showed a poor agreement with planimetry, whereas continuity equation and the modified continuity equation revealed a very good agreement. Planimetry of the LVOT displayed an elliptic shape of the LVOT in all patients with the minimum diameter perpendicular to the 3CV, which was the reason for the above mentioned underestimation. CONCLUSION The LVOT area calculated from the 3CV-LVOT diameter underestimates the LVOT area compared to planimetry due to an elliptic shape of the LVOT in patients with non-stenotic as well as with stenotic aortic valves. The modified Gorlin equation proved to be less useful to assess AVA in non-stenotic valves, whereas the continuity equation and a modified continuity equation displayed a very good agreement with planimetric area measurements.

Assessment of myocardial perfusion for detection of coronary artery stenoses by steady-state, free-precession magnetic resonance first-pass imaging.

Objective: To evaluate the diagnostic impact of magnetic resonance imaging (MRI) first-pass perfusion using steady-state, free-precession (SSFP) sequences with parallel imaging (SENSE) for detection of coronary stenoses. Design: Prospective observational study. Setting: University hospital, cardiac MRI and catheterisation laboratories. Patients and methods: 228 patients were examined with coronary angiography and MRI (1.5 T Intera CV). A three-slice, short-axis SSFP perfusion scan with a saturation prepulse was performed during infusion of adenosine and at rest followed by myocardial scar (late enhancement) imaging. Gadolinium-DTPA was given at 0.1 mmol/kg body weight. Perfusion images were visually assessed. Analysis for myocardial hypoperfusion was done according to patient group and according to vessel. Results: Sensitivity, specificity and accuracy of MRI first-pass perfusion for detection of a coronary artery stenosis (>50% luminal narrowing) in the total patient group were 93.0%, 85.7%, 91.2% and for a significant lesion (>70% luminal narrowing) 96.1%, 72.0%, 88.2%, respectively. Based on 536 coronary artery territories without myocardial scar, the sensitivity of MRI perfusion analysis for detection of a significant lesion was for the left anterior descending artery 91.4%, for the circumflex artery 81.6% and for the right coronary artery 65.1% (p<0.001). Conclusions: MRI first-pass perfusion analysis using an SSFP sequence with three myocardial slices was a highly accurate diagnostic method for detection of coronary artery stenoses. This MRI technique can be included in daily practice and has the potential to guide the indication for invasive coronary angiography.

Whole-heart coronary vein imaging: a comparison between non-contrast-agent- and contrast-agent-enhanced visualization of the coronary venous system.

The feasibility of three‐dimensional (3D) whole‐heart imaging of the coronary venous (CV) system was investigated. The hypothesis that coronary magnetic resonance venography (CMRV) can be improved by using an intravascular contrast agent (CA) was tested. A simplified model of the contrast in T2‐prepared steady‐state free precession (SSFP) imaging was applied to calculate optimal T2‐preparation durations for the various deoxygenation levels expected in venous blood. Non‐contrast‐agent (nCA)‐ and CA‐enhanced images were compared for the delineation of the coronary sinus (CS) and its main tributaries. A quantitative analysis of the resulting contrast‐to‐noise ratio (CNR) and signal‐to‐noise ratio (SNR) in both approaches was performed. Precontrast visualization of the CV system was limited by the poor CNR between large portions of the venous blood and the surrounding tissue. Postcontrast, a significant increase in CNR between the venous blood and the myocardium (Myo) resulted in a clear delineation of the target vessels. The CNR improvement was 347% (P < 0.05) for the CS, 260% (P < 0.01) for the mid cardiac vein (MCV), and 430% (P < 0.05) for the great cardiac vein (GCV). The improvement in SNR was on average 155%, but was not statistically significant for the CS and the MCV. The signal of the Myo could be significantly reduced to about 25% (P < 0.001). Magn Reson Med 57:1019–1026, 2007.

Nonautonomous Kolmogorov parabolic equations with unbounded coefficients

We study a class of elliptic operators A with unbounded coeffi- cients defined in I × R d for some unbounded interval IR. We prove that, for any s 2 I, the Cauchy problem u(s,·) = f 2 Cb(R d ) for the parabolic equation Dtu = Au admits a unique bounded classical solution u. This allows to associate an evolution family {G(t, s)} with A, in a natural way. We study the main properties of this evolution family and prove gradient estimates for the function G(t, s)f. Under suitable assumptions, we show that there exists an evolution system of measures for {G(t, s)} and we study the first properties of the extension of G(t, s) to the L p -spaces with respect to such measures.

Magnetic resonance imaging to assess acute changes in atrial and ventricular parameters after transcatheter closure of atrial septal defects

To evaluate acute changes in atrial and ventricular parameters by the use of cardiac magnetic resonance imaging (MRI) in patients with percutaneous transcatheter atrial septal defects (ASD) closure.

Detection of long-term progression of myocardial fibrosis in Duchenne muscular dystrophy in an affected family: a cardiovascular magnetic resonance study.

BACKGROUND Detection of myocardial fibrosis and left ventricular dysfunction in Duchenne muscular dystrophy (DMD) is the corner stone for further therapeutic studies. Little is known about the ability of cardiac magnetic resonance imaging (CMR) to evaluate progression of myocardial fibrosis. Aim of our study was to provide CMR data in a previously genotyped DMD family and to evaluate whether progression of myocardial fibrosis could be visualized. METHODS AND RESULTS DMD genotypes were available in 14 family members. CMR was performed in 4/5 carrier females, in 2/2 affected males and in one healthy family member with normal genotype. Functional images and late gadolinium enhanced (LGE) images in contiguous short-axis orientation were acquired at baseline and follow-up of 1231 days CMR examination could be repeated in three carrier females, in one affected male and in the healthy subject previously scanned. Mean decrease of left ventricular ejection fraction during the follow-up period was 10.5±11.0%, mean progression of LGE volume 11.7±9.5%. CONCLUSIONS Myocardial fibrosis seems to occur prior to global left ventricular dysfunction in DMD diseased males and carrier females. CMR could be used to evaluate progression of myocardial fibrosis and left ventricular function and may thus serve as an important diagnostic tool in the evaluation of therapeutical options in DMD.

Cardiac involvement in a female carrier of Duchenne muscular dystrophy

A 42 year-old female carrier of Duchenne muscular dystrophy (DMD) was referred with suspected subacute myocarditis and non-sustained ventricular tachycardia. Echochardiography and cardiac catheterization revealed severely reduced left ventricular function (LVF). Coronary artery disease was excluded. Cardiac magnetic resonance imaging showed transmural, intramural and subepicardial late gadolinium enhancement. Myocardial biopsy excluded viral infection and showed severe myopathic changes with abnormal expression of dystrophin and utrophin. Moleculargenetic analysis of the DMD gene revealed frameshift duplication of exon 2. The patient received conventional heart failure therapy, implantable cardioverter/defibrillator-implantation and prednisolone to attenuate cardiac degradation. 6 months later she had improved clinically though LVF was still severely reduced.

Effect of bivalirudin compared with unfractionated heparin plus abciximab on infarct size and myocardial recovery after primary percutaneous coronary intervention: The horizons‐AMI CMRI substudy

Background: Myocardial infarct size is a strong independent predictor of mortality in patients with ST‐elevation myocardial infarction (STEMI). In the Harmonizing Outcomes with RevasculariZatiON and Stents in Acute Myocardial Infarction (HORIZONS‐AMI) trial, bivalirudin compared with unfractionated heparin plus a glycoprotein IIb/IIIa inhibitor reduced cardiac mortality in STEMI patients, which was attributed to reduced major bleeding. Whether a possible reduction in infarct size with bivalirudin may have contributed to the enhanced survival with this agent is unknown. Methods: Cardiac magnetic resonance imaging was performed within 7 days and after 6 months in 51 randomized patients from a single center in HORIZONS‐AMI trial (N = 28 bivalirudin, N = 23 heparin plus abciximab). Infarct size, microvascular obstruction (MVO), left ventricular ejection fraction (LVEF), and LV end‐diastolic and end‐systolic volume indices were evaluated. Results: Infarct size was not significantly different after treatment with bivalirudin compared with heparin plus abciximab either within 7 days (median 9.3% [interquartile range 4.9%, 26.6%] vs. 20.0% [5.9%, 28.2%], P = 0.28) or at 6 months 6.7% [3.8%, 20.0%] vs. 8.2% [1.8%, 16.5%], P = 0.73). MVO was present in 28.6% versus 34.8% of patients respectively (P = 0.63). LVEF and LV volume indices also did not significantly differ between the two groups at either time period, nor were differences in myocardial recovery evident. Conclusions: In conclusion, in the HORIZONS‐AMI Cardiac magnetic resonance imaging (CMRI) substudy, cardiac magnetic resonance imaging within 7 days and at 6 months after primary percutaneous coronary intervention (PCI) did not demonstrate significant differences in infarct size, MVO, LVEF, or LV volume indices in patients treated with bivalirudin compared with unfractionated heparin plus abciximab.

A Pettis-type integral and applications to transition semigroups

Motivated by applications to transition semigroups, we introduce the notion of a norming dual pair and study a Pettis-type integral on such pairs. In particular, we establish a sufficient condition for integrability. We also introduce and study a class of semigroups on such dual pairs which are an abstract version of transition semigroups. Using our results, we give conditions ensuring that a semigroup consisting of kernel operators has a Laplace transform which also consists of kernel operators. We also provide conditions under which a semigroup is uniquely determined by its Laplace transform.