Klaus Kettering

Image quality and diagnostic accuracy of non-invasive coronary imaging with 16 detector slice spiral computed tomography with 188 ms temporal resolution

Objective: To evaluate image quality and clinical accuracy in detecting coronary artery lesions with a new multidetector spiral computed tomography (MDCT) generation with 16 detector slices and a temporal resolution of 188 ms. Methods: 124 consecutive patients scheduled for invasive coronary angiography (ICA) were additionally studied by MDCT (Sensation 16 Speed 4D). MDCTs were analysed with regard to image quality and presence of coronary artery lesions. The results were compared with ICA. Results: 120 of 124 scans were successful. The image quality of all remaining 120 scans was sufficient (mean (SD) heart rate 64.2 (9.8) beats/min, range 43–95). The mean calcium mass was 167 (223) mg (range 0–1038). Thirteen coronary segments were evaluated for each patient (1560 segments in total). Image quality was graded as follows: excellent, 422 (27.1%) segments; good, 540 (34.6%) segments; moderate, 277 (17.7%) segments; heavily calcified, 215 (13.8%) segments; and blurred, 106 (6.8%) segments. ICA detected 359 lesions with a diameter stenosis > 50% and MDCT detected 304 of 359 (85%). Sensitivity, specificity, and positive and negative predictive values were 85%, 98%, 91%, and 96%, respectively. The correct clinical diagnosis (presence or absence of at least one stenosis > 50%) was obtained for 110 of 120 (92%) patients. Conclusions: MDCT image quality can be further improved with 16 slices and faster gantry rotation time. These results in an unselected population underline the potential of MDCT to become a non-invasive diagnostic alternative, especially for the exclusion of coronary artery disease, in the near future.

Efficacy of Metoprolol and Sotalol in the Prevention of Recurrences of Sustained Ventricular Tachyarrhythmias in Patients with an Implantable Cardioverter Defibrillator

KETTERING, K., et al.: Efficacy of Metoprolol and Sotalol in the Prevention of Recurrences of Sustained Ventricular Tachyarrhythmias in Patients with an Implantable Cardioverter Defibrillator. ICDs provide protection against sudden cardiac death in patients with life‐threatening ventricular arrhythmias. Nevertheless, most ICD recipients receive adjunctive antiarrhythmic drug therapy to reduce the number of recurrent episodes and ICD discharges. The aim of the study was to compare the efficacy of metoprolol and d,l‐sotalol in preventing VT/VF recurrences in patients with an ICD in a prospective, randomized trial. One hundred patients (83 men, 17 women; mean age 59 years, SD ± 11 years) were randomized to receive metoprolol or sotalol after implantation of an ICD. There were no significant differences between the two groups with regard to age, sex, underlying cardiac disease, left ventricular ejection fraction, NYHA class assessment and clinical arrhythmia. The median follow‐up was 728 days (25th percentile: 530 days, 75th percentile: 943 days) in the metoprolol group and 727 days (25th percentile: 472 days, 75th percentile: 1,223 days) in the sotalol group (P = 0.52). Thirty‐three patients treated with metoprolol and 30 patients receiving sotalol had at least one episode during the follow‐up. Event‐free survival curves were generated for the two treatment arms using the Kaplan‐Meier method and showed no significant difference (P = 0.68). Eight patients treated with metoprolol and six patients treated with sotalol died during follow‐up. Total mortality was not significantly different between the two study groups (P = 0.43). Metoprolol is as efficacious as sotalol in preventing VT/VF recurrences in patients with an ICD.

Long-term experience with subcutaneous ICD leads: a comparison among three different types of subcutaneous leads.

ICDs provide protection against sudden cardiac death in patients with life‐threatening arrhythmias. Nevertheless, efficacy of defibrillation remains an important issue to guarantee the future safety of patients who receive an ICD. There is a significant number of patients who need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J between the maximum output of the ICD and the energy needed for ventricular defibrillation. However, few data exists about the long‐term performance of different types of subcutaneous leads. Therefore, the aim of this study was to analyze the long‐term experience with three different types of subcutaneous leads. The study included 132 patients (109 men, 23 women; mean age 59.8 years [SD ± 10.7 years]). All of them received a subcutaneous lead in addition to a single chamber or dual chamber ICD between October 1990 and April 2002. Two patients received a second subcutaneous lead after the first lead had been removed so that a total of 134 subcutaneous leads were evaluated. Inclusion criteria for the implantation of an additional subcutaneous lead were (1) unsuccessful ventricular defibrillation at implant without a subcutaneous lead, (2) insufficient safety margin (< 10 J) between the maximum output of the ICD and the energy needed for ventricular defibrillation, or (3) clinical evaluation of a new subcutaneous lead (Medtronic 13014). There were no significant differences between the three study groups with regard to age, sex, underlying cardiac disease, left ventricular ejection fraction, NYHA class assessment and clinical arrhythmia. The results of the DFT testing during follow‐up (prehospital discharge test and 1 and 3 years) were compared to the baseline value obtained during the implantation procedure. All lead related complications were analyzed. Eighty‐two single element subcutaneous array electrodes (SQ‐A1), 31 subcutaneous three‐finger electrodes (SQ‐A3), and 21 subcutaneous patch electrodes (SQ‐P) were implanted during the study period. The median follow‐up was 1,499 days (25th percentile: 798 days, 75th percentile: 1,976 days) in the SQ‐A1 group, 2,209 days (25th percentile: 1,242 days, 75th percentile: 2,710 days) in the SQ‐A3 group, and 1,419 days (25th percentile: 787 days, 75th percentile: 2,838 days) in the SQ‐P group. None of the three groups had a significant change of the DFT during follow‐up compared to baseline. Major complications occurred in six (7.3%) patients in group SQ‐A1 and in two (9.5%) patients in group SQ‐P. There were no major complications in group SQ‐A3. Kaplan‐Meier curves analyzing freedom from subcutaneous lead related complications did not show a significant difference between the three study groups (P = 0.16). SQ‐A1, SQ‐A3, and SQ‐P leads provide stable DFTs during long‐term follow‐up. Major complications are rare. However, a careful follow‐up including chest radiographs at regular intervals is needed to detect potentially fatal complications like lead fractures.

Enhanced detection criteria in implantable cardioverter defibrillators: sensitivity and specificity of the stability algorithm at different heart rates.

KETTERING, K., et al.: Enhanced Detection Criteria in Implantable Cardioverter Defibrillators: Sensitivity and Specificity of the Stability Algorithm at Different Heart Rates. Sensitivity and Specificity of the Stability Algorithm at Different Heart Rates. The lack of specificity in the detection of ventricular tachyarrhythmias remains a major clinical problem in the therapy with ICDs. The stability criterion has been shown to be useful in discriminating ventricular tachyarrhythmias characterized by a small variation in cycle lengths from AF with rapid ventricular response presenting a higher degree of variability of RR intervals. But RR variability decreases with increasing heart rate during AF. Therefore, the aim of the study was to determine if the sensitivity and specificity of the STABILITY algorithm for spontaneous tachyarrhythmias is related to ventricular rate. Forty‐two patients who had received an ICD (CPI Ventak Mini I, II, III or Ventak AV) were enrolled in the study. Two hundred ninety‐eight episodes of AF with rapid ventricular response and 817 episodes of ventricular tachyarrhythmias were analyzed. Sensitivity and specificity in the detection of ventricular tachyarrhythmias were calculated at different heart rates. When a stability value of 30 ms was programmed the result was a sensitivity of 82.7% and a specificity of 91.4% in the detection of slow ventricular tachyarrhythmias (heart rate < 150 beats/min). When faster ventricular tachyarrhythmias with rates between 150 and 169 beats/min (170–189 beats/min) were analyzed, a stability value of 30 ms provided a sensitivity of 94.5% (94.7%) and a specificity of 76.5% (54.0%). For arrhythmia episodes ≥ 190 beats/min, the same stability value resulted in a sensitivity of 78.2% and a specificity of 41.0%. Even when other stability values were taken into consideration, no acceptable sensitivity/specificity values could be obtained in this subgroup. RR variability decreases with increasing heart rate during AF while RR variability remains almost constant at different cycle lengths during ventricular tachyarrhythmias. Thus, acceptable performance of the STABILITY algorithm appears to be limited to ventricular rate zones < 170 beats/min.

Hypoxia and Myocardial Remodeling in Human Cardiac Allografts: A Time-course Study

BACKGROUND Cardiac allografts are known to develop myocardial fibrosis, which may be a cause of progressive cardiac dysfunction. Apart from the renin-angiotensin and transforming growth factor-beta system, hypoxia has been proposed as an important player in the pathogenesis of fibrosis, but its significance remains unclear. This study examines the degree of myocardial fibrosis, cellular remodeling and hypoxic signaling over a time-course of 10 years after human cardiac allograft transplantation. METHODS Serial right ventricular biopsies of 57 patients were collected in 6-month intervals after cardiac transplant surgery for a total of 10 years to allow a retrospective longitudinal analysis. Over this period, tissue remodeling, including interstitial fibrosis and cellular changes, were determined morphometrically. Immunohistochemistry (IHC) was used to analyze expression of the following hypoxia-related proteins: hypoxia-induced factor 1-alpha (HIF1alpha); the oxygen sensor prolyl hydroxylase 3 (PHD3); and vascular endothelial growth factor (VEGF). RESULTS Fibrosis increased significantly from 12.6 +/- 6.5% at the point of transplantation throughout follow-up to 28.8 +/- 7.7% at 10 years. The DNA content and number of nuclei changed over the period of follow-up, displaying signs of cellular hypertrophy and a loss of myocytes. Whereas HIF1alpha expression revealed a U-shaped pattern with both early and late elevation during fibrogenesis, PHD3 and VEGF expression patterns showed a gradual increase with PHD3 decreasing again in later fibrogenesis. CONCLUSIONS In cardiac allografts, extensive and progressive tissue remodeling is present. Hypoxia may play a role in this process by up-regulating HIF1alpha and leading to differential regulation of pro-angiogenic signals.

Atrial linear lesions: feasibility using cryoablation.

Background: Long linear lesions are created in the left atrium to modify the atrial substrate, thereby curing atrial fibrillation. The creation of long linear left atrial lesions using radiofrequency (RF) ablation is time consuming and difficult. Furthermore, it might result in significant complications. Cryoablation might overcome some of the disadvantages of RF ablation. Therefore, the aim of our study was to assess whether the creation of a long linear lesion is possible using cryotherapy.

Catheter ablation of an incessant ventricular tachycardia originating from the left aortic sinus cusp in an adolescent with subacute myocarditis

because of recurrent dizziness and palpitations. On admission, several twelve-lead ECG recordings showed an incessant ventricular tachycardia (VT) with an inferior axis and a left bundle branch block pattern (approximately 130 beats/min; Fig. 1a). There was a history of palpitations (for 1 month), but no structural heart disease. The tachycardia was poorly tolerated by the patient. She suffered from severe dizziness during VT episodes and was transferred to the intensive care unit. Laboratory tests did not reveal any abnormalities and there was no evidence for myocardial ischemia or an acute inflammatory process. Antiarrhythmic drug therapy was initiated using a beta blocker (starting with an intravenous application of esmolol, followed by the oral administration of metoprolol succinate (100 mg/d)). Nevertheless, the patient suffered from further repetitive sustained and non-sustained episodes of a monomorphic ventricular tachycardia with the above-mentioned morphology. All episodes terminated without any intervention (maximum duration: 30 min). However, the tachycardia developed an incessant character. A transthoracic echocardiographic evaluation revealed a moderately impaired left ventricular ejection fraction (possibly related to the incessant tachycardia). In coincidence with the echocardiographic findings, magnetic resonance imaging of the heart (MRI; 1.5 T Magnetom Sonata; Siemens Medical Solutions, Forchheim, Germany) showed a slightly reduced left ventricular function and a normal right ventricle with no evidence for a right ventricular dysplasia. A distinct edema was found in the interventricular septum and in the adjacent part of the aortic root (Fig. 2). The MRI findings suggested a subacute inflammatory process of the myocardium affecting mainly the septum and the adjacent wall of the aortic root (based on fat-suppression sequences as well as on late gadoliniumenhanced images). The patient continued to have repetitive episodes of the ventricular tachycardia for more than one week. Therefore, the decision was taken to perform a VT ablation as a curative approach.

Addition of a Defibrillation Electrode in the Low Right Atrium to a Right Ventricular Lead Does Not Reduce Ventricular Defibrillation Thresholds

Transvenous unipolar active can defibrillation systems have proven to be effective in treating ventricular tachyarrhythmias. However, a further reduction of ventricular defibrillation thresholds (V‐DFT) would increase the longevity, reduce the size of pulse generators, and help to avoid additional leads in patients with inacceptable high V‐DFTs. In a finite difference computer model, the extension of the right ventricular (RV) defibrillation coil into the low right atrium led to a 40% reduction of unipolar V‐DFT. To evaluate this finding, we conducted a prospective, randomized study in 11 patients receiving an ICD. Extension of the RV electrode was simulated by adding a second coil placed in the low right atrium with the same polarity. Using a binary search protocol, V‐DFT was determined with and without the additional electrode in each patient. Total shock impedance was significantly lower in the two coil (low RA) configuration, compared to the single coil (RV) configuration. Corresponding values were 49.9 ± 6.7 Ohm and 61.1 ± 9.3 Ohm, respectively (P < 0.01, paired t‐test). However, there was no reduction, but even a nonsignificant increase in V‐DFTs. Mean V‐DFT in the RV configuration was 12.0 ± 5.6 J and 16.3 ± 7.8 J in the low RA configuration (P = 0.09, paired t‐test). Despite a reduction in total impedance, the addition of a defibrillation coil in the low right atrium does not reduce ventricular defibrillation thresholds. (PACE 2004; 27:346–351)

Catheter ablation of atrial fibrillation: Radiofrequency catheter ablation for redo procedures after cryoablation

AIM To evaluate the effectiveness of two different strategies using radiofrequency catheter ablation for redo procedures after cryoablation of atrial fibrillation. METHODS Thirty patients (paroxysmal atrial fibrillation: 22 patients, persistent atrial fibrillation: 8 patients) had to undergo a redo procedure after initially successful circumferential pulmonary vein (PV) isolation with the cryoballoon technique (Arctic Front Balloon, CryoCath Technologies/Medtronic). The redo ablation procedures were performed using a segmental approach or a circumferential ablation strategy (CARTO; Biosense Webster) depending on the intra-procedural findings. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic. A 7-day Holter monitoring was performed at 3, 12 and 24 mo after the ablation procedure. RESULTS During the redo procedure, a mean number of 2.9 re-conducting pulmonary veins (SD ± 1.0 PVs) were detected (using a circular mapping catheter). In 20 patients, a segmental approach was sufficient to eliminate the residual pulmonary vein conduction because there were only a few recovered pulmonary vein fibres. In the remaining 10 patients, a circumferential ablation strategy was used because of a complete recovery of the PV-LA conduction. All recovered pulmonary veins could be isolated successfully again. At 2-year follow-up, 73.3% of all patients were free from an arrhythmia recurrence (22/30). There were no major complications. CONCLUSION In patients with an initial circumferential pulmonary vein isolation using the cryoballoon technique, a repeat ablation procedure can be performed safely and effectively using radiofrequency catheter ablation.

Wie nützlich sind die Algorithmen zur Differentialdiagnostik der monomorphen Tachykardien mit breitem QRS-Komplex in kardiologischen Notfällen?@@@How Useful Are the Algorithms for the Differential Diagnosis of the Monomorphic Tachycardias with Broad QRS Complex in Cardiac Emergencies?

ZusammenfassungDiese Übersicht stellt die drei alten und die zwei neuen EKG-Algorithmen zur Differentialdiagnose der monomorphen regulären Tachykardien mit breitem QRS-Komplex zusammenfassend dar. Mehrere Studien haben nachgewiesen, dass die Diagnose einer Kammertachykardie von den Notfallärzten oder Ärzten in der Notaufnahme nur in 35–50% der Fälle richtig gestellt wird. Ob ein Algorithmus im klinischen Alltag die Diagnostik wirklich verbessern kann und ob die Algorithmen für die Ärzte praktikabel sind, ist bisher noch nicht geklärt worden.Die Algorithmen besitzen in den prospektiven Studien eine hohe Sensivität von 88–95%, aber eine nur zufriedenstellende Spezifität von 73–80%. Die Wertigkeit aller Algorithmen ist vergleichbar. In den Händen wenig erfahrener Ärzte dürfte die Inzidenz der korrekten Diagnosen deutlich geringer sein. Die Algorithmen haben erhebliche Limitationen, vor allem bei der Verwendung der „Morphologiekriterien“. Da die Nichterkennung einer Kammertachykardie fatale Folgen für den Patienten haben kann, sollte in Notfällen jede Tachykardie mit breitem QRS-Komplex als Kammertachykardie behandelt werden. Eine diagnostische Gabe von Adenosin kann bei hämodynamisch stabilen Patienten sofort zur einen korrekten Diagnosestellung führen. Aufgrund der Studienlage wurde ein Schema zur Differentialdiagnostik anhand sehr einfacher, für jeden Arzt erkennbarer EKG-Kriterien erstellt.AbstractThis review gives an integrated summary of the three old and two new ECG algorithms for the differential diagnosis of monomorphic regular tachycardias with broad QRS complex. Several studies have provided evidence that a ventricular tachycardia was diagnosed correctly by doctors on call and emergency physicians only in 35–50% of cases. Whether an algorithm may really improve diagnosis in everyday clinical practice and whether the algorithms are feasible for physicians, has not yet been clarified.The algorithms possess a high sensitivity of 88–95%, but only a satisfactory specificity of 73–80%. The values of all algorithms are similar. In the hands of physicians with little experience, the incidence of correct diagnoses is likely to be markedly lower. The algorithms have considerable limitations, especially with regard to the application of the “morphology criteria”. As the nondetection of a ventricular tachycardia can have fatal consequences for the patient, any tachycardia with broad QRS complex should be treated as ventricular tachycardia in emergencies. In hemodynamically stable patients, the administration of adenosine for diagnostic purposes should immediately lead to a correct diagnosis. Based on the study situation, a schematic representation for the differential diagnosis has been created which follows very simple ECG criteria identifiable by any physician.