Dieter Hammel

Impact of a Molecular Approach to Improve the Microbiological Diagnosis of Infective Heart Valve Endocarditis

Background—Even today, infective endocarditis (IE) remains a severe and potentially fatal disease demanding sophisticated diagnostic strategies for detection of the causative microorganisms. Despite the use of appropriate laboratory techniques, classic microbiological diagnostics are characterized by a high rate of negative results. Methods and Results—Broad-range polymerase chain reaction (PCR) targeting bacterial and fungal rDNA followed by direct sequencing was applied to excised heart valves (n=52) collected from 51 patients with suspected infectious endocarditis and from 16 patients without any signs of IE during an 18-month period. The sensitivity, specificity, and the positive and negative predictive values for the bacterial broad-range PCR were 41.2%, 100.0%, 100.0%, and 34.8%, respectively, compared with 7.8%, 93.7%, 80.0%, and 24.2% for culture and 11.8%, 100.0%, 100.0%, and 26.2% for Gram staining. Without exception, database analyses allowed identification up to the (sub)species level comprising streptococcal (n=13), staphylococcal (n=4), enterococcal (n=2), and other signature sequences such as Bartonella quintana and Nocardia paucivorans. Fungal ribosomal sequences were not amplified. All valve tissues of the reference group were negative for both PCR and conventional methods, except one sample that was contaminated by molds. Conclusions—Culture-independent molecular methods substantially improve the diagnostic outcome of microbiological examination of excised heart valves. Importantly, this was true not only for fastidious, slow-growing, and/or nonculturable microorganisms but also for easy-to-culture pathogens such as streptococci and staphylococci. Both patient management and empiric antibiotic therapy of IE are likely to benefit from improved knowledge of the spectrum of pathogens now causing IE.

Intraoperative Radiofrequency Ablation of Chronic Atrial Fibrillation: A Left Atrial Curative Approach by Elimination of Anatomic “Anchor” Reentrant Circuits

Intraoperative Ablation of Atrial Fibrillation. Introduction: The percutaneous approach to radiofrequency (RF) catheter ablation for curative treatment of atrial fibrillation (AF) is an investigational technique, and the optimal composition of lesion lines is unknown. We tested an intraoperative RF ablation concept with elimination of left atrial anatomic “anchor” reentrant circuits.

Left ventricular pressure and volume unloading during pulsatile versus nonpulsatile left ventricular assist device support

BACKGROUND Nonpulsatile axial or centrifugal pumps are the latest generation of left ventricular assist devices (LVAD). Whether left ventricular (LV) unloading and outcome in these devices is similar to pulsatile LVADs during long-term support has not been investigated. We compared LV unloading and mortality between different types of LVAD support (pulsatile versus nonpulsatile). METHODS In 31 patients undergoing long-term LVAD implantation (nonpulsatile = 10, pulsatile = 21) preoperative and postoperative echocardiographic and hemodynamic assessment with right heart catheterization had been obtained. RESULTS All patients had similar echocardiographic, hemodynamic, and clinical heart failure characteristics at baseline. The degree of LV pressure unloading was the same in both device types, caused by similar reduction of mean pulmonary pressure (18.6 +/- 5.1 versus 18.3 +/- 7.5 mm Hg) and pulmonary capillary wedge pressure (8.9 +/- 4.4 versus 8.0 +/- 7.0 mm Hg). Left ventricular volume unloading was pronounced with a pulsatile device owing to a statistically significant higher pump output (5.1 +/- 1.0 L/min) in comparison with nonpulsatile LVADs (3.6 +/- 0.9 L/min, p < 0.001). Echocardiographic-determined end-systolic indicators confirm this augmentation in pulsatile LVADs. Etiology or the time interval of hemodynamic reassessment had no impact in left ventricular pressure unloading, but LV volume unloading decreased between day 60 and 120 in patients with nonpulsatile LVADs. The preoperative and postoperative transplant mortality was comparable in both groups. CONCLUSIONS Left ventricular pressure unloading is similar in patients with nonpulsatile as compared with pulsatile implantable long-term assist devices. Left ventricular volume unloading is pronounced in pulsatile LVADs.

Do patients with an implantable defibrillator live longer

OBJECTIVES This study was done to provide information on the potential benefit of implantable cardioverter-defibrillator therapy regarding sudden and arrhythmia-related deaths and to examine whether such therapy improves survival. BACKGROUND Implantation of automatic cardioverter-defibrillators is reported to abort sudden cardiac death due to malignant tachyarrhythmias. METHODS Between 1989 and 1992, 107 patients were screened for implantation of a third-generation implantable cardioverter-defibrillator combined with endocardial leads. Mean age was 57 +/- 13 years and mean ejection fraction was 40 +/- 15%. Sudden death, total arrhythmia-related death and total cardiac death were compared with the occurrence of fast ventricular tachyarrhythmias (> 240 beats/min), assuming that most of these arrhythmias would have been fatal without treatment by the implantable cardioverter-defibrillator. RESULTS The surgical mortality rate was 2.7% in all 107 patients and 1% in the 99 patients who qualified for endocardial leads. During a follow-up period of 12 +/- 8 months, actuarial survival rate free of events at 6 months as well as at 12 and 18 months was 100% for sudden death, 97% for total arrhythmia-related death and 95% for total cardiac death. In contrast, after 6, 12 and 18 months, the rate of survival free of fast ventricular tachycardia was only 83%, 74% and 69%, respectively, and the rate of survival free of any ventricular tachyarrhythmia was only 59%, 49% and 40%, respectively. CONCLUSIONS The outcome of patients treated with an implantable cardioverter-defibrillator and endocardial defibrillation leads is excellent. For many patients, this treatment is probably lifesaving.

Cerebral and Systemic Embolization During Left Ventricular Support With the Novacor N100 Device

BACKGROUND Patients undergoing implantation of left ventricular assist systems (LVAS) are prone to thromboembolic complications. We analyzed the incidence, clinical findings, and outcome of neurologic and systemic thromboembolic events (TE) in patients with the Novacor N100 LVAS. In a subset of patients, transcranial Doppler sonography was used to detect microembolic signals. METHODS Thirty-six patients underwent implantation of a Novacor N100 LVAS for various reasons. The surgical procedure was elective in 18 patients and scheduled on an urgent or emergency basis in another 18 patients. The assist period lasted from 17 to 336 days (109 +/- 88 days); 22 patients were forwarded to heart transplantation after being supported for 140 +/- 87 days. RESULTS Clinical cerebral embolism was evident in 17 patients (47%). Thromboembolic events were singular in 8 and multiple in 9 patients; in the latter up to 10 TE occurred (mean +/- SD, 1.4 +/- 2 TE). Leading neurologic symptoms were unilateral hemiplegia in 11, as well as ocular symptoms and aphasia in 12 patients each. Noncerebral TE were detected in 4 patients, 2 of whom underwent an emergency operation for intestinal and iliac artery occlusion. The incidence of TE did not correlate strongly with the interval of LVAS support. Cerebral computed tomography confirmed lesions in 58% of patients. Transcranial Doppler sonography detected microembolic signals on 67% of all recordings, with the microembolic signals being more frequent on days with clinically manifest TE. The outcomes were good, as only 2 patients suffer from neurologic sequelae. CONCLUSIONS Thromboembolism is still a major threat for patients with LVAS implantation. Neurologic sequelae are frequent but have a favorable prognosis, and systemic complications occur considerably less often. Patient selection, adequate anticoagulation, and transcranial Doppler sonography may help to reduce the incidence of TE.

Potential Benefit From Implantable Cardioverter-Defibrillator Therapy in Patients With and Without Heart Failure

BACKGROUND Whether patients with heart failure derive a benefit from therapy with implantable cardioverter-defibrillators (ICDs) has been questioned. The purpose of this study was to investigate whether New York Heart Association (NYHA) functional class had an impact on the potential benefit from ICD therapy as assessed from data stored in the memory of ICDs. METHODS AND RESULTS Between 1989 and 1996, 603 patients (77% men; 59% with coronary artery disease and 16% with dilated cardiomyopathy; age, 57+/-13 years; ejection fraction, 44+/-18%) were treated with an ICD with extended memory function (storage of electrograms and/or RR intervals from treated episodes) in combination with endocardial lead systems. The stages of heart failure (NYHA functional class I through III) at implantation were correlated with overall mortality and the recurrence of fast ventricular tachyarrhythmias (>240 bpm) during follow-up. The potential benefit of the device was estimated as the difference between overall mortality and the hypothetical death rate had the device not been implanted. The latter was based on the recurrence of fast and, without termination by the devices, presumably fatal ventricular tachyarrhythmias. In the overall group, a significant difference between hypothetical death rate and overall mortality was observed (13.9%, 23.5%, and 26.6% at 1, 3, and 5 years, respectively) that suggested a benefit from ICD implantation. In patients in NYHA class I, the estimated benefit, which increased over time, was 15.2%, 29.2%, and 35.6% after 1, 3, and 5 years, respectively. In patients in NYHA class II or III, the estimated benefit increased until the third year (21.8% and 21.9%, respectively) and then remained constant until the fifth year (22.9% and 23.8%, respectively). Even those patients in NYHA class III with a history of decompensated heart failure benefited from ICD implantation. CONCLUSIONS Analysis of stored ECG data suggests that in patients with a history of ventricular tachycardia or ventricular fibrillation, ICD therapy may lead to a prolongation of life in NYHA classes I through III. The initial benefit is greatest in patients in NYHA class II and class III, but the estimated benefit might persist longest for patients in NYHA class I.

Implantable cardioverter defibrillator therapy in patients with arrhythmogenic right ventricular cardiomyopathy, long QT syndrome, or no structural heart disease

Recent technical developments in implantable cardioverter defibrillator (ICD) systems and reduced operative mortality and morbidity rates associated with ICD implantation have expanded the indications for ICD treatment of ventricular tachyarrhythmias. This review summarizes data regarding ICD therapy in patients with arrhythmogenic right ventricular cardiomyopathy, long QT syndrome, and idiopathic ventricular fibrillation and presents preliminary concepts for identification of patients who will benefit more from ICD therapy than from pharmacologic and other nonpharmacologic approaches. Recent studies suggest that ICD therapy may improve long-term prognosis by reliably terminating recurrences of life-threatening arrhythmias. Appropriate ICD therapies during mean follow-up periods of 12 to 36 months occurred in 30% of patients with idiopathic ventricular fibrillation to 50% of patients with arrhythmogenic right ventricular cardiomyopathy and long QT syndrome. At present no strict recommendations can be given for ICD implantation in these patients. However, at least in cardiac arrest survivors in whom the clinical arrhythmia is not reproducibly inducible during electrophysiologic study, ICD therapy appears to be superior to other treatment options with regard to long-term survival and thus should be considered as a first-line treatment. We are hopeful that continued study of long-term follow-up with and without ICD treatment and improved risk stratification will lead to better criteria for selection of treatment options.

Comparison of d,l-Sotalol and Implantable Defibrillators for Treatment of Sustained Ventricular Tachycardia or Fibrillation in Patients With Coronary Artery Disease

BACKGROUND Implantable cardioverter-defibrillators (ICDs) and d,l-sotalol are widely used to treat ventricular tachyarrhythmia and ventricular fibrillation (VT/VF). The purpose of this study was to compare the long-term efficacy of d,l-sotalol and ICDs in patients with coronary artery disease. METHODS AND RESULTS In a case-control study, 50 patients treated with oral d,l-sotalol were matched to 50 patients treated with ICDs. Both groups were matched for sex (82 men), age (58 +/- 10 years), ejection fraction (40 +/- 12%), extent of coronary artery disease, presenting arrhythmia, and year that treatment began. In all patients in the sotalol group, VT/VF was inducible in the drug-free electrophysiological study. Induction of sustained VT/VF was suppressed by d,l-sotalol (438 +/- 95 mg/d). In the ICD group, either VT/VF was not inducible (n = 5) or inducible sustained VT/VF was refractory to antiarrhythmic drug treatment (n = 45). Sotalol treatment led to a marked reduction in arrhythmic events. Whereas 83% of the patients in the sotalol group were free of sudden death and nonfatal VT at 3 years, only 33% of the ICD patients did not receive appropriate ICD therapies (P < .005). Actuarial rates for absence of sudden death at 3 years were 85% in the sotalol group and 100% in the ICD group (P < .005). Actuarial rates for overall survival at 3 years were 75% in the sotalol group and 85% in the ICD group (P = .02). CONCLUSIONS In this case-control study, ICD therapy was more effective tha electrophysiologically guided antiar-rhythmic treatment with d,l-sotalol in prevention of sudden death and reduction of total morality in patients with coronary artery disease. Prospective studies are needed to confirm these results.

Selection and management of ventricular assist device patients : The Muenster experience

BACKGROUND Because of the growing discrepancy between the availability of donor organs and the number of patients with end-stage heart disease who need heart transplantation, a larger proportion of patients waiting for a suitable donor heart require pre-operative mechanical circulatory assistance. The criteria for the selection and management of these patients as applied at Muenster University Hospital are reviewed. METHODS The study population consists of 631 patients referred to our center for transplantation between January 1, 1990, and December 31, 1996. Two hundred ninety-seven patients were listed for transplantation and 157 were transplanted. Of 41 patients who underwent implantation of a ventricular assist device (n = 34, Novacor; n = 6, TCI HeartMate; n = 1, Medos), 39 received the device as a bridge to transplantation and 2 as permanent support. For the purpose of the analysis, the study population was divided into 3 groups (elective bridging, urgent bridging, emergency bridging) and compared with heart transplant candidates who did not require mechanical circulatory assistance. RESULTS Patients who underwent elective or urgent assist-device implantation were younger and had greater hemodynamic compromise than the remainder of patients waiting for heart transplantation, as suggested by a higher functional class and lower mean arterial pressure, cardiac index, serum sodium, and pulmonary artery wedge pressure. Survival of patients who electively underwent implantation of an assist device was better than that of patients who were stable on the waiting list and did not undergo heart transplantation during follow-up. CONCLUSIONS This finding suggests that earlier implantation of assist devices may facilitate resolution of organ dysfunction before heart transplantation.

A prospective randomized cross-over comparison of mono- and biphasic defibrillation using nonthoracotomy lead configurations in humans.

Biphasic Defibrillation with Nonthoracotomy Leads. Introduction: For current implantable defibrillators, the nonthoracotomy approach to implantation fails in a substantial number of patients. In a prospective randomized cross‐over study the defibrillation efficacy of a standard monophasic and a new biphasic waveform was compared for different lead configurations.