Christian Perings

Incidence and clinical outcome of iatrogenic femoral arteriovenous fistulas: Implications for risk stratification and treatment

OBJECTIVES We sought to determine the incidence of arteriovenous fistulas (AVF), identify risk factors for AVF, and follow up the clinical outcome of femoral AVF. BACKGROUND Arteriovenous fistulas are a potential harmful complication of cardiac catheterization. Incidence and clinical outcome of iatrogenic AVF are unknown so far, although important for risk stratification and treatment. METHODS A total of 10,271 consecutive patients undergoing cardiac catheterization were followed up prospectively over a period of three years. Diagnosis of AVF was performed by duplex sonography. RESULTS The incidence of AVF was 0.86% (n = 88). The following significant and independent risk factors for AVF were identified: high heparin dosage (odds ratio [OR]) = 2.88), coumadin therapy (OR = 2.34), puncture of the left groin (OR = 2.21), arterial hypertension (OR = 1.86), and female gender (OR = 1.84). Within 12 months 38% of all AVF closed spontaneously. No signs of cardiac volume overload or limb damage were observed in patients with persisting AVF. None of the risk factors for AVF influenced the incidence or the rate of AVF closure. Only intensified anticoagulation showed a tendency to extend AVF persistence. CONCLUSIONS Almost 1% of patients undergoing cardiac catheterization acquire femoral AVF, for which patient- and procedure-related risk factors could be identified. One-third of iatrogenic AVF close spontaneously within one year. Cardiac volume overload and limb damage are highly unlikely with AVF persistence. Thus, a conservative management for at least one year seems to be justified.

T Wave Alternans as a Risk Predictor in Patients with Cardiomyopathy and Mild-to-Moderate Heart Failure

The analysis oft wave alternans (TWA) was introduced to identify patients with an increased risk of ventricular tachyarrhythmias. The inducibility of ventricular tach‐yarrhythmias and the spontaneous arrhythmic events are correlated with a positive TWA in patients with a reduced left ventricular ejection fraction and survived myocardial infarction. In contrast, this study is the first to investigate the correlation of a survived sudden cardiac death and TWA in patients without coronary heart disease and only slightly decreased left ventricular function. Sixty patients were included in the study. The TWA analysis was performed using the Cambridge Heart system (CH2000). Patients were sitting on a bicycle ergometer and exercised with a gradual increase of workload to maintain a heart rate of at least 105 beats/min. The exercise test was stopped after recording 254 consecutive low noise level heart beats. The electrocardiographic signals were digitally processed using a spectral analysis method. The magnitude of TWA was measured at a frequency of 0.5 cycles/beat. A TWA was defined as positive if the ratio between TWA and noise level was > 3.0 and the amplitude of the TWA was > 1.8 μV. Twelve (20%) of the included 60 patients showed a positive TWA. The sensitivity concerning a previous arrhythmic event amounted to 65%, the specificity up to 98%, respectively. The alternans ratio was significantly higher in patients with a previous event (30.3 ± 53.2 vs 2.9 ± 5.9, P < 0.001) and cumulative alternans voltage (4.67 ± 3.55 vs 1.75 ± 1.88 μV, P < 0.001). In 19 patients, invasively investigated by an electro‐physiological study, a significant correlation between inducibility of tachyarrhythmias and a positive TWA result was found (Spearman R = 0.51, P = 0.01). In conclusion, the TWA analysis seems to identify patients with nonischemic Cardiomyopathy who are at an increased risk of ventricular tachyarrhythmias.

Defibrillation Energy Requirements with Single Endocardial (Endotak™) Lead

The need for thoracotomy in usually high risk patients has limited the use of the implantable cardioverter defibrillator. Initial clinical results with endocardial and subcutanous patch electrodes (SQPs) are en couraging. Using a single endocardial lead in the absence of a SQP for chronic implantation of the cardioverter defibrillator, the goal of the study was to obtain defibrillation thresholds (DFTs) of 15 Joules (J) or less and to investigate changes in DFT over time. We tested 19 consecutive patients (15 men, 4 women] age 62 ± 8.5 years with malignant ventricular arrhythmias (14 VT/5 VF). The underlying heart disease was coronary artery disease in 15 pafients, dilative cardiomyopathy in two patients, and primary electricaJ disease in two patients. Four patients had undergone previous cardiac surgery. Left ventricular ejection fraction ranged between 14% and 66% (39%± 12.6%). Pacing thresholds (0.54 ± 0.17 Vat 0.5 msec), R wave amplitude for pacemaker sensing (14.2 ± 7.0 mV), slew rate (2.12 ± 1.4 V/sec), and resistance (500.3 ± 73.9 W) were sufficient in all patients. Eighteen patients met our endocardial impiant criteria with a DFT ≤ 15 J (10.05 ± 4.03 J) using monophasic (14 patients) or biphasic (four patients) pulse wave forms. In the one remaining patient, with a DFT of 20 J, we implanted a SQP but there was no reduction of the DFT. All patients tested showed successful defibrillation prior to discharge. During follow‐up of 88 patient‐months (1–9 months), 114 spontaneous VT/VF episodes occurred in five patients and were all successfully terminated. Eleven patients with a minimum follow‐up of 2 months were reassessed. In seven out of 11 patients, termination of VF was achieved with the same minimal energy requirements obtained intraoperatively. In three patients, DFT increased by 5 J (one patient) and 10 J (two patients). In a further patient, X ray revealed dislocation of the endocardial lead. Our data suggest that effective defibrillation is feasible with a single endocardial lead for implantation of cardioverter defibrillator. In addition, we strongly recommend repetitive x‐ray control to detect asymptomatic lead dislocation. Despite stable DFTs in most of our patients, an energy difference of ≤ 15 J between acute DFT and cardioverter defibrillator energy rating seems to be currently desirable to ensure successful postoperative defibrillation.

T Wave Alternans and Ventricular Arrhythmias in Arterial Hypertension

Patients with a positive microvolt-level T wave alternans (TWA) are characterized by an increased risk of ventricular tachyarrhythmias. Arterial hypertension leads to an increase of sudden cardiac death risk, particularly if left ventricular hypertrophy is present. The aim of this study was to investigate the value of TWA in patients with arterial hypertension. Fifty-one consecutive patients were included in the study. TWA analysis was performed with patients sitting on a bicycle ergometer and exercising with a gradual increase of workload to maintain a heart rate of at least 105/min. After recording 254 consecutive low-noise-level heartbeats, the exercise test was stopped. The ECG signals were digitally processed by a spectral analysis method. The magnitude of TWA was measured at a frequency of 0.5 cycle per beat. A TWA was defined as positive if the ratio between TWA and noise level was >3.0 and the amplitude of the TWA was >1.8 &mgr;V. Eight of the 51 patients (16%) showed a positive TWA. If left ventricular hypertrophy was present, the prevalence of TWA was higher (33.3% versus 8.3%;P <0.05). Sensitivity concerning a previous arrhythmic event was 73%, and specificity was 100%. The alternans ratio was significantly higher in patients with a previous event (39.3±62.3 versus 2.4±4.6;P <0.001), as was the cumulative alternans voltage (4.7±4.1 versus 1.6±1.9 &mgr;V;P <0.001). In 16 patients invasively investigated by an electrophysiological study, a significant correlation between inducibility of tachyarrhythmias and a positive TWA result was found (Spearman R =0.36, P =0.01). We conclude that the arrhythmic risk of patients with arterial hypertension is markedly increased if microvolt-level TWA is present. The prevalence of TWA is higher in patients with left ventricular hypertrophy.

Chemoreflexsensitivity in chronic heart failure patients

Patients with heart failure are characterised by a disturbed sympathovagal balance, as could be shown by analyses of heart rate variability and baroreflexsensitivity. Furthermore, the modulation of ventilation is disturbed in those patients with an increased ventilation volume following the inhalation of hypoxic gas. This study should evaluate, whether heart failure patients have a decreased hyperoxic chemoreflexsensitivity associated with an increased rate of ventricular arrhythmias.

Chemoreflexsensitivity in Patients with Survived Sudden Cardiac Arrest and Prior Myocardial Infarction

For evaluation of patients with an increased risk of sudden cardiac death, the analyses of ventricular late potentials, heart rate variability, and baroreflexsensitivity are helpful. But so far, the prediction of a malignant arrhythmic event is not possible with sufficient accuracy, For a better risk stratification other methods are necessary. In this study the importance of the ChRS for the identification of patients at risk for ventricular tachyarrhythmic events should be investigated. Of 41 patients included in the study, 26 were survivors of sudden cardiac arrest. Fifteen patients were not resuscitated, of whom 6 patients had documented monomorphic ventricular tachycardia and 9 had no ventricular tachyarrhythmias in their prior history. All patients had a history of an old myocardial infarction (> 1 year ago). For determination of the ChRS the ratio between the difference of the RR intervals in the ECG and the venous pO2 before and after a 5‐minute oxygen inhalation via a nose mask was measured (ms/mmHg). The 26 patients with survived sudden cardiac death showed a significantly decreased ChRS compared to those patients without a tachyarrhythmic event (1.74 ± 1.02 vs 6.97 ± 7.14 ms/mmHg, P < 0.0001). The sensitivity concerning a survived sudden cardiac death amounted to 88% for a ChRS below 3.0 ms/mmHg. During a 12‐month follow‐up period, the ChRS was significantly different between patients with and without an arrhythmic event (1.64 ± 1.06 vs 4.82 ± 5.83 ms/mmHg, P < 0.01). As a further method for evaluation of patients with increased risk of sudden cardiac death after myocardial infarction the analysis of ChRS seems to be suitable and predicts arrhythmias possibly more sensitive than other tests of neurovegetative imbalance. The predictive importance has to be examined by prospective investigations in larger patient populations.

Effects of right coronary artery PTCA on variables of P-wave signal averaged electrocardiogram.

Background: P‐wave signal averaged ECG has been used to detect atrial late potentials that were found in paroxysmal atrial fibrillation. Ischemia is supposed to trigger ventricular late potentials, which indicate an elevated risk for ventricular tachycardia. Preexistent ventricular late potentials measured by ventricular signal averaged ECG is supposed to be eliminated by successful PTCA.

Chemoreflex sensitivity as a predictor of arrhythmia relapse in ICD recipients

BACKGROUND The chemoreflex sensitivity as a marker of a disturbed vagal reflex activity has proved to be a parameter of increased risk for ventricular tachyarrhythmias or sudden cardiac death. The sensitivity of patients with prior myocardial infarction concerning ventricular tachyarrhythmias amounted to about 70%. This prospective study should evaluate the positive predictive accuracy of this new method in patients at risk for ventricular arrhythmias. METHODS 42 patients were enrolled into this study. All had a prior myocardial infarction at least 6 months previously; 35 patients were resuscitated from sudden cardiac death, and seven patients had documented monomorphic ventricular tachycardias. All patients were recipients of an ICD. The chemoreflex sensitivity was measured by determination of the venous partial pressure of oxygen and the heart rate before and after inhalation of pure oxygen. The difference in the RR-intervals before and after inhalation divided by the difference in the oxygen pressures were calculated as the chemoreflex sensitivity [ms/mmHg]. Furthermore, in all patients additional risk stratifiers used in this study were the presence of ventricular late potentials (LP), the short-term heart rate variability (HRV), the baroreflex sensitivity (BRS) and a decreased left ventricular function (ejection fraction<40%, EF). RESULTS The chemoreflex sensitivity in the patient group as a whole amounted to 2.59+/-2.06 ms/mmHg. During follow-up, out of the 42 patients enrolled, 20 had a documented arrhythmic event (AE: sustained ventricular tachycardia or ventricular fibrillation). Patients with and without AE showed significantly different values of chemoreflex sensitivity (1.58+/-1.09 vs. 3.51+/-2.31 ms/mmHg, P<0.01) and EF (33.3+/-15.6 vs. 47.9+/-17.9%, P<0.05), but not of LP, HRV or BRS. The relative risk of reduced chemoreflex sensitivity concerning an AE amounted to 2.83 (95% CI 0.99-8.01). CONCLUSIONS The chemoreflex sensitivity as a marker of increased risk for ventricular tachyarrhythmias shows a high positive predictive power in patients with prior myocardial infarction and who previously survived ventricular tachyarrhythmias. These results should be confirmed by studies in broad populations and without survived arrhythmic event.

Der Nachweis atrialer Spätpotentiale mittels P-Wellen-Signalmittelungs-EKG bei Patienten mit paroxysmalem Vorhofflimmern

The analysis of the QRS-complex with signal averaged ECG (SAECG) has been evaluated for patients affected by ventricular tachycardia for a long time. A longer filtered QRS-complex was a marker of a slower ventricular conduction velocity and reentry tachycardia. This method was modified for an analysis of the P wave (P-SAECG). Different filter methods were evaluated for the analysis of atrial late potentials. Method: We measured the bidirectional P wave signal averaged ECG of 45 consecutive patients with (group A) and without (group B) paroxysmal atrial fibrillation (PAF) and 15 young volunteers without a cardiac disease (group C). Results: As a result patients with PAF had a significantly lower root mean square voltage of the last 20 ms (RMS 20) (2.59±0.89 vs 4.08±1.45μV, p<0.0003) and a significantly longer filtered P wave duration (FPD) than patients of the control collective (139.2±17.5 vs 115.1±17.7 ms, p<0.0001) and the young volunteers (3.44±0.95μV, p<0.0001/101.9±14.2 ms, p<0.009). Furthermore we found an age-dependent relationship of FPD between group B and C (115.1±17.7vs 101.9±14.2 ms, p<0.05) but not an age-dependent relationship of the RMS 20 (4.08±1.45 vs 3.44±0.95μV, p=n.s.). A specificity of 80% and a sensitivity of 78% was achieved for identifying patients with atrial fibrillation by using a definition of atrial late potentials as FPD >120 ms and a RMS 20 <3.5μV. Conclusions: The analysis of the P-SAECG can be used as a noninvasive method for identifying atrial late potentials. Atrial late potentials might be a reason for PAF. The predictive power of atrial late potentials has to be examined by prospective investigations of a larger patient population. Das Signalmittelungs-EKG (SAEKG) wird zur Analyse des QRS-Komplexes schon seit langem für die Evaluation von Patienten mit ventrikulären Tachykardien angewandt. Hierbei konnte der Nachweis eines verlängerten QRS-Komplexes als Marker für eine ventrikuläre Leitungsverzögerung und Reentrytachykardien dargestellt werden. Darüber hinaus ist diese Technik auch zur Analyse der P-Welle (P-SAEKG) erweitert worden. Es wurden verschiedene Filtertechniken zur Evaluation der P-Wellen-Spätpotentiale entwickelt. Methodik: Unter Verwendung eines bidirektionalen Filters wurde bei je 28 konsekutiven Patienten mit (Gruppe A) und ohne (Gruppe B, Kontrollkollektiv) bekanntem paroxysmalem Vorhofflimmern (PAF) sowie einem Kollektiv von 15 jungen Patienten (Gruppe C) ohne kardiale Grunderkrankung eine P-Wellen-Spätpotentialanalyse durchgeführt. Ergebnisse: Das Ergebnis dieser Messungen zeigte eine signifikant erniedrigten root mean square voltage der letzten 20 ms (RMS 20) (2,59±0,89 vs. 4,08±1,45μV, p<0,0003) sowie eine signifikant längere Dauer der gefilterten P-Welle (FPD) bei Patienten mit bekanntem PAF gegenüber dem Kontrollkollektiv (139,2±17,5 vs 115,1±17,7 ms, p<0,0001) sowie den Patienten ohne kardiale Grunderkrankung (3,44±0,95μV, p<0,0001/101,9±14,2 ms, p<0,009). Zudem konnte ein altersabhängiger Unterschied in Bezug auf die FPD zwischen dem Kontrollkollektiv sowie den Patienten ohne kardiale Grunderkrankung mit einer altersabhängigen Zunahme der FPD festgestellt werden (115,1±17,7 vs. 101,9±14,2 ms, p<0,05) jedoch ohne Nachweis einer Altersabhängigkeit des RMS 20 (4,08±1,45 vs. 3,44±0,95μV, p=n.s.).    Bei einer Definition atrialer Spätpotentiale mit einer FPD länger als 120 ms und RMS 20 kleiner als 3,5μV wurde eine Sensitivität von 78% und eine Spezifität von 80% für Patienten mit PAF erzielt. Schlussfolgerungen: Die Analyse des P-SAEKG kann als nicht invasive Methode zur Erfassung von atrialen Spätpotentialen verwendet werden. Das Vorhandensein atrialer Spätpotentiale könnte als Risikoprediktor für das Auftreten von PAF verwendet werden. Die prädiktive Bedeutung muss durch eine prospektive Untersuchung an einem großen Patientenkollektiv gesichert werden.

Determinanten des paroxysmalen Vorhofflimmerns bei Patienten mit arterieller Hypertonie

Introduction: Atrial fibrillation represents an important arrhythmia, in particular in patients with arterial hypertension. Hitherto, the connection between paroxysmal atrial fibrillation, left atrial size and left ventricular muscle mass has not been investigated sufficiently. In the present study, determinants of paroxysmal atrial fibrillation in patients with arterial hypertension were evaluated. Methods: 104 consecutive patients were enrolled into this study. All of them suffered from arterial hypertension for more than one year. Persistent or permanent atrial fibrillation was not documented. In all of these patients, clinical, echocardiographic and rhythmologic variables were evaluated. Results: In 10.3% of the patients, paroxysmal atrial fibrillation was found. These patients showed a significantly larger left atrium (43.3±6.7 vs 37.5±4.9mm, p<0.001), a significantly higher muscle mass of the left ventricle (152.38±43.57 vs 134.41±27.19g/m2, p<0.01) and significantly more frequent a mild mitral regurgitation (38.1 vs 28.6%, p<0.01). The multivariate regression analysis revealed as independent factors for paroxysmal atrial fibrillation the size of the left atrium and the presence of mild mitral regurgitation. Independent factors for an enlarged left atrium were mitral insufficiency and left ventricular muscle mass. Conclusion: This study shows that paroxysmal atrial fibrillation in aterial hypertension is based on the left atrial size, and left atrial size on left ventricular muscle mass. Therefore, these results should lead to a causal therapy for treatment of paroxysmal atrial fibrillation in these patients. Einleitung: Vorhofflimmern stellt eine insbesondere für Hypertoniker klinisch bedeutsame Arrhythmie dar. Der Zusammenhang zwischen paroxysmalem Vorhofflimmern, linksatrialer Vorhofgröße und ventrikulärer Muskelmasse ist bisher allerdings noch unzureichend untersucht. In der vorliegenden Studie sollten Determinanten des paroxysmalen Vorhofflimmerns bei Patienten mit arterieller Hypertonie erfasst werden. Methoden: In diese Studie wurden 104 Patienten eingeschlossen. Alle hatten eine über ein Jahr bestehende arterielle Hypertonie. Persistierendes oder permanentes Vorhofflimmern bestand nicht. Bei diesen wurden neben klinischen die echokardiographischen und rhythmologischen (24-Stunden-EKG) Daten erfasst. Ergebnisse: Insgesamt wurde in 10,3% der Fälle paroxysmales Vorhofflimmern festgestellt. Diese Patienten wiesen einen signifikant größeren linken Vorhof auf (43,3±6,7 vs. 37,5±4,9mm, p<0,001), daneben eine signifikant höhere linksventrikuläre Muskelmasse (152,38±43,57 vs. 134,41±27,19g/m2, p<0,01) und häufiger eine leichtgradige Mitralinsuffizienz (38,1 vs. 28,6%, p<0,01) als Patienten mit durchgehendem Sinusrhythmus. Die multivariate Regressionsanalyse erbrachte als unabhängige Parameter für das Auftreten von Vorhofflimmern die Größe des linken Vorhofes und das Vorhandensein einer Mitralinsuffizienz. Für die Vergrößerung des linken Vorhofes wurden ebenfalls die Mitralinsuffizienz, aber auch die linksventrikuläre Muskelmasse als unabhängige Parameter identifiziert. Zusammenfassung: Diese Studie zeigt, dass paroxysmales Vorhofflimmern bei Hypertonikern vor allem durch die linksatriale Größe bestimmt wird, welche aber wiederum insbesondere durch die linksventrikuläre Muskelmasse beeinflusst wird. Damit sollten diese Ergebnisse vorherrschend zu einer Kausaltherapie zur Behandlung von paroxysmalem Vorhofflimmern bei diesen Patienten führen.