[Importance of the history and the utilization of therapy guidelines in patients with arrhythmias]. / Bedeutung der Anamnese und der Umsetzung von Therapieleitlinien bei Rhythmuspatienten.

In this article criteria for taking the history in patients with manifest or potential life threatening arrhythmias are outlined. The importance of a sound (family) history is demonstrated. Besides specific correlates for arrhythmias in the history of a patient, the long term consequences of dyspnoe on exertion and hypertension are outlined. In 80% of patients sudden death is due to myocardial ischemia or interstitial myocardial fibrosis which in turn result from acquired diseases such as coronary artery disease and hypertension. Against this background the importance of the prevention of sudden cardiac death by nonantiarrhythmics drugs is stressed. Examples of under-utilization of therapy guidelines are given with special reference to beta-blocker therapy.

Altered dynamics of action potential restitution and alternans in humans with structural heart disease.

BACKGROUND: Restitution kinetics and alternans of ventricular action potential duration (APD) have been shown to be important determinants of cardiac electrical stability. In this study, we tested the hypothesis that APD restitution and alternans properties differ between normal and diseased human ventricular myocardium. METHODS AND RESULTS: Monophasic action potentials were recorded from the right ventricular septum in 24 patients with structural heart disease (SHD) and in 12 patients without SHD. Standard and dynamic restitution relations were constructed by plotting APD as a function of the preceding diastolic interval. The dynamic restitution relation of both groups showed a steeply sloped segment at short diastolic intervals that was associated with the occurrence of APD alternans. Patients with SHD had a wider diastolic interval range over which APD alternans was present (mean+/-SEM 68+/-11 versus 12+/-2 ms) and showed an earlier onset (168+/-7 versus 225+/-4 bpm) and an increased magnitude (20+/-2 versus 11+/-2 ms) of APD alternans compared with patients without SHD. The occurrence of APD alternans during induced ventricular tachycardia (6 episodes) and during rapid pacing could be derived from the dynamic restitution function. CONCLUSIONS: There are marked differences in the dynamics of APD restitution and alternans in the ventricular myocardium of patients with SHD compared with patients without SHD. These differences may contribute importantly to cardiac electrical instability in diseased human hearts and may represent a promising target for antiarrhythmic substrate modification.

Effect of pacing current strength on indexes of myocardial activation in humans: influence of chronic infarction and polarity of pacing.

The effects of current strength (threshold to 20 mA) and pacing polarity (bipolar versus unipolar) on indexes of ventricular activation during endocardial pacing (cycle length 400 to 500 ms) from 10 normal and 17 abnormal left ventricular sites were assessed in 19 patients. Abnormal sites were infarcted and demonstrated an electrogram duration greater than 70 ms and amplitude less than 3 mV during sinus rhythm. Bipolar pacing was performed from poles 1 (cathode) and 3 (1 cm interelectrode distance) of a quadripolar catheter. Unipolar cathodal pacing was performed from the tip electrode (pole 1). Local activation was indexed by the interval from the pacing stimulus to 1) the onset of the QRS complex, 2) the largest rapid deflection of the local electrogram, and 3) the end (total duration) of the local electrogram recorded from poles 2 and 4 of the quadripolar catheter used for left ventricular pacing. Distant activation was indexed by the interval from pacing stimulus to electrograms recorded at the right ventricular apex and outflow tract. Bipolar and unipolar pacing of normal sites produced a modest homogeneous reduction of all activation times by 3 to 11 ms (median) with increments in current strength from threshold (0.8 mA) to 20 mA. Bipolar pacing of abnormal sites showed marked (up to 110 ms) and heterogeneous changes in local (median 22 to 30 ms) as well as distant (median 14 to 23 ms) activation times with increases in current strength from threshold (2.7 mA) to 20 mA.(ABSTRACT TRUNCATED AT 250 WORDS)

Closed chest catheter ablation of an accessory pathway in a patient with permanent junctional reciprocating tachycardia.

This report describes a 23 year old woman with a lifelong history of permanent junctional reciprocating tachycardia refractory to conventional antiarrhythmic medications who was successfully treated with closed chest, transvenous selective ablation of a posteroseptal bypass tract. Two 100 J (stored) direct-current shocks were delivered to the region of the os of the coronary sinus using a quadripolar catheter positioned in the coronary sinus. At a 2 month follow-up interval, the patient is asymptomatic without recurrence of the tachycardia. It is concluded that in patients with permanent junctional reciprocating tachycardia, selective catheter ablation of a posteroseptal accessory pathway is a feasible alternative to a difficult pharmacologic regimen or to ablative surgery.

Subthreshold atrial pacing in patients with a left-sided accessory pathway: an effective new method for terminating reciprocating tachycardia.

This study investigated the possibility of terminating reciprocating atrioventricular (AV) tachycardia using subthreshold atrial pacing. Ten patients with a left-sided accessory pathway and sustained AV tachycardia underwent subthreshold atrial pacing from the coronary sinus site closest to insertion of the accessory pathway. In seven of these patients, the tachycardia could be reliably terminated with subthreshold atrial overdrive pacing. When pacing at a cycle length of 80 +/- 23% of the tachycardia cycle length, the minimal subthreshold current that was effective in tachycardia termination was 64 +/- 14% of threshold current and the maximal ineffective current was 49 +/- 17% of threshold (p less than 0.05). In all cases, the tachycardia was terminated by one or two instances of atrial capture that resulted in a premature atrial impulse (20 +/- 4% advancement of the atrial cycle) that blocked the AV node limb of the tachycardia. Anterograde conduction over the accessory pathway never occurred, either during the tachycardia or during subthreshold pacing after a return to normal sinus rhythm. No instances of atrial fibrillation were provoked by subthreshold pacing. Possible explanations for the intermittent atrial capture with critically placed subthreshold impulses include supernormal atrial conduction or summation of impulses at the atrial insertion site of the accessory pathway. It is concluded that subthreshold pacing is effective in selected patients with AV tachycardia due to an accessory pathway. Furthermore, because neither atrial fibrillation nor anterograde conduction over the accessory pathway is seen with subthreshold pacing, this modality may hold significant promise for permanent antitachycardia pacing in these patients.

Selective perfusion of ischemic myocardium during coronary venous retroinjection: a study of the causative role of venoarterial and venoventricular pressure gradients.

Coronary venous retroinjection is often associated with preferential distribution of flow to ischemic myocardium. The purpose of this study was to define the mechanism of such retrodistribution of flow. In 24 anesthetized open chest dogs, Monastral blue dye (10 ml) was injected by way of a balloon catheter in the distal great cardiac vein as a marker for retrograde flow distribution. The injection rate (0.6 to 2.4 ml/s) was adjusted such that systolic pressure in the anterior interventricular vein ranged between 60 and 85 mm Hg. In 11 dogs with no ischemia and normal myocardial perfusion pressure (96 +/- 8 mm Hg), no myocardial staining occurred despite retrograde filling of epicardial veins. One minute after occlusion of the left anterior descending coronary artery, dye injections caused selective staining of the cyanotic area in 15 of 18 episodes, sparing the normal myocardium within the zone of retroperfused veins. In five dogs, with the arterial pressure less than 55 mm Hg, retroinjection resulted in homogeneous staining of all the myocardium drained by the retroperfused veins. Selective staining of the ischemic myocardium caused by retroinjection was associated with the following pressure gradients: during systole from the anterior interventricular vein to the occluded coronary artery, 31 to 58 mm Hg, and during diastole from the retroperfused veins to the left ventricular chamber, 9 to 28 mm Hg. There was no diastolic venoarterial gradient in the ischemic myocardium. In normal myocardium, retroinjection did not reverse the arteriovenous pressure gradient. In conclusion, retrograde flow is primarily directed to myocardium with low anterograde perfusion pressure. Selective retrograde penetration of acutely ischemic myocardium can thus be achieved by a mechanism consistent with the development of venoarterial and venoventricular pressure gradients.

Relation of monophasic action potential recorded with contact electrode to underlying transmembrane action potential properties in isolated cardiac tissues: a systematic microelectrode validation study.

Monophasic action potentials, recorded with contact non-suction electrodes, have been used both clinically and experimentally. However, to date no systematic microelectrode validation studies have been done to underlying myocardial cell populations from different myocardial regions with different transmembrane potential profiles. In the present study transmembrane action potential properties, recorded with standard microelectrodes, were compared with monophasic action potentials recorded with contact electrodes in three different (endocardium, epicardium, and free running Purkinje fibre) isolated canine preparations during pacing and during spontaneous automatic activity. The mean transmembrane durations at 50% and 90% repolarisations (APD50 and APD90) of 19-30 cells at a monophasic action potential recording site was not statistically significant from monophasic action potential duration in all three tissue preparations studied. However, in endocardial preparations, composed of superficial (1-2 cell layers) Purkinje fibres with deeper ventricular muscle cells, the APD50 (139(17) ms) and APD90 (181(26) ms) of monophasic action potentials more closely reflected (but not significantly different) the underlying deeper ventricular muscle cells (APD50 134(14) ms and APD90 167(15) ms) rather than the mean transmembrane action potential durations of the underlying most superficial Purkinje fibres (166(22) ms for APD50 and 210(30) ms for APD90) (p less than 0.025). Tetrodotoxin (TTX) at 1 x 10(-6) mol.litre-1 shortened Purkinje fibre action potential duration and slightly lengthened that of ventricular muscle. Simultaneously recorded monophasic action potential showed an intermediate change in action potential duration. Incremental pacing and applied single premature stimuli resulted in similar degrees of shortening of action potential duration for both monophasic action potential and transmembrane potential in all three preparations. In endocardial preparations, barium chloride (4 mmol.litre-1) superfusion induced early afterdepolarisations, and spontaneous phase 4 depolarisations (n = 6) in both Purkinje and ventricular muscle cells giving rise to spontaneous automatic activity. These abnormal automatic activities were accurately detected by simultaneous monophasic action potential recordings. Suppression of automaticity by verapamil (0.2-0.5 micrograms.ml-1) as confirmed by transmembrane action potential recordings were similarly detected by monophasic action potential recordings (ABSTRACT TRUNCATED AT 250 WORDS)

Decline in ventricular fibrillation threshold after successive premature extrastimuli: a possible explantation for the induction of ventricular fibrillation during programmed stimulation with multiple extrastimuli.

To examine the relation between the ventricular fibrillation threshold and the number of premature extrastimuli delivered to the right ventricle during programmed ventricular stimulation, a clinical stimulation protocol was performed in nine normal, anaesthetised, closed chest dogs. In addition, the ventricular fibrillation threshold was measured in each dog after a train of eight paced (S1) beats (VFT-S2), after a single premature extrastimulus (VFT-S3), and after two extrastimuli (VFT-S4). The VFT-V3 was 32% lower than the VFT-S2 (16(7) mA vs 24(9) mA, p less than 0.001). The VFT-S4, or the current required by the S4 extrastimulus to induce ventricular fibrillation, was 25% lower than the VFT-S3 (12(8) mA vs 16(7) mA, p less than 0.05). The cumulative reduction in the ventricular fibrillation threshold measured by the S1S2S3S4 stimulation protocol was approximately 50%. Although in most dogs the VFT-S4 was still considerably higher than twice threshold current intensity, the results of the study suggest that a possible mechanism for the induction of non-clinical ventricular fibrillation in the clinical electrophysiology laboratory may be the progressive lowering of the ventricular fibrillation threshold caused by the addition of multiple extrastimuli. This may be particularly relevant in patients with an already reduced fibrillation threshold.

Breath-to-breath variability correlates with apnea-hypopnea index in obstructive sleep apnea.

BACKGROUND: Breathing in patients with obstructive sleep apnea (OSA) is frequently interrupted by periods of hypopnea and apnea. There is limited information regarding a possible disturbance of breathing outside these periods. STUDY OBJECTIVE: To analyze the degree of breathing disturbance during nonocclusion. DESIGN: Prospective determination of breathing variability during full polysomnographic sleep studies. PATIENTS: Breath-to-breath variation was monitored in 34 patients with OSA and in 9 healthy subjects. MEASUREMENTS AND RESULTS: All breath-to-breath intervals were automatically analyzed from flow signal, displayed, and manually corrected for artifacts. Distribution of all nonapneic breath intervals was analyzed for the extent of difference from a normal distribution pattern by specifying kurtosis. In untreated OSA patients, kurtosis was significantly reduced (0.0 +/- 0.5, mean +/- SD) compared to control subjects (0.8 +/- 0.5), indicating increased variability of nonoccluded breathing. This effect was present in all sleep stages, and the extent depended significantly on the degree of disease. Continuous positive airway pressure breathing was able to normalize kurtosis (1.0 +/- 0.9) immediately. CONCLUSIONS: Breathing in OSA is not only characterized by interruptions of breathing during occlusion, but by a greater variation in the pattern of normal-length breaths.

[Solitary liver tumor as a manifestation of polyarteritis nodosa]. / Solitärer Lebertumor als Manifestation der Panarteriitis nodosa.

HISTORY: A 65-year-old female was admitted with fever of unknown origin. DIAGNOSTIC PROCEDURES: Abdominal computed tomography showed a solid mass (7.5 cm in diameter) with central fluid, located in the right lobe of the liver. Fine-needle aspiration cytology was unremarkable. Further work-up procedures for suspected liver abscess included colonoscopy, which surprisingly revealed adenocarcinoma at 13 cm from the anal orifice. THERAPY AND CLINICAL COURSE: Both lesions in the rectum and liver were resected. While a moderately differentiated (G2) adenocarcinoma of the rectosigmoid junction (stage T3/ N0) was confirmed, histology of the hepatic mass showed liver infarction due to polyarteritis nodosa of the medium-sized arteries. Treatment with 20 mg/d prednisolone was initiated and tapered off over the next three months. The clinical course after discontinuation of corticosteroids was unremarkable over a 6-month follow-up. CONCLUSION: It is suggested that polyarteritis nodosa of the liver occurred in this patient as a paraneoplastic phenomenon and subsided after resection of colorectal cancer and short-term immunosuppression with prednisolone.

[Combined coronary angioplasty and aortic valve valvulotomy]. / Kombinierte koronare Angioplastie und Aortenklappenvalvulotomie.

Because of treatment-resistant angina, percutaneous coronary angioplasty was performed at the same time as aortic valvotomy in a 74-year-old woman with calcific aortic stenosis and coronary heart disease. There were no complications and good angiographic, haemodynamic and clinical results were obtained. It is concluded that combined valvotomy and coronary angioplasty can be recommended as palliative treatment in elderly patients in whom operation would carry an increased risk.

Independent autonomic modulation of the human sinus and AV nodes: evidence from beat-to-beat measurements of PR and PP intervals during sleep.

INTRODUCTION: Evidence from animal experiments indicates that the autonomic nervous system may influence the sinus (SA) and atrioventricular (AV) nodes differently. We investigated, therefore, whether there are spontaneous functional differences in the innervation of the SA and AV nodes in man. METHODS AND RESULTS: This study was performed in 10 healthy males (ages 21 to 26 years) during strict bed rest from 10 pm to 6 am. Three ECG leads were digitized on-line. PR and PP intervals were determined on a beat-to-beat basis off-line using a correlation algorithm with an accuracy of +/- 2 msec and were verified visually. During major body movements, there were sudden decreases in PP intervals of 36 to 827 msec (mean 335) for periods of 6 to 265 seconds (mean 24). During these phases of heart rate (HR) acceleration, PR intervals showed either concomitant shortening (9 to 30 msec), no change, or lengthening (6 to 25 msec). Furthermore, tonic changes in the PR interval occurred over 15-minute periods during which the range of PP intervals was constant. Additionally, recovery-adjusted PR interval (PR-b2/RP) and cycle length were negatively correlated for some periods, which confirmed independent autonomic effects on SA node and AV node. CONCLUSION: Beat-to-beat measurement of PR intervals allows for evaluation of autonomic effects on the human AV node. The different patterns in PR intervals during sudden spontaneous increases in HR and the tonic changes in PR interval indicate that the autonomic inputs to the SA and AV nodes are, in principle, independent of each other.

[Congenital aneurysm of the membranous interventricular septum]. / Angeborenes Aneurysma des membranösen interventrikulären Septums.

In a 50-year-old patient with complex ventricular arrhythmia (monotopic ventricular extrasystoles in bigeminy and triplet form), coronary angiography with ventriculography revealed an aneurysm of about 2-3 cm diameter that bulged visibly into the right ventricle during the systole. Electrophysiology was able to localise the earliest excitation during the ventricular extrasystoles at the septal border of the aneurysm. Hence, the congenital aneurysm was definitely identified as the source of the arrhythmia. Surgery or drug therapy were not indicated since there was no haemodynamically effective ventricular tachycardia in the patient who was largely free from complaints.

[Neurocardiogenic convulsive syncope--differential diagnosis, pathophysiology and therapy based on a case report]. / Die neurokardiogene konvulsive Synkope--Differentialdiagnose, Pathophysiologie und Therapie anhand eines Fallberichts.

Neurocardiogenic convulsive syncope as a disease at the border between cardiovascular and neurologic dysfunction can pose considerable diagnostic challenges. We report on the case of a 19 year-old female patient with recurrent neurocardiogenic convulsive syncope where the time from the onset of symptoms to the correct diagnosis and initiation of an effective therapy spanned more than three years. Based on this case report, we discuss differential diagnosis, pathophysiology and therapy of this disorder of autonomic cardiovascular regulation. Neurocardiogenic convulsive syncope should be considered whenever a patient has both syncope that exhibits a typical cardiovascular pattern (e.g., fainting of short duration with rapid reorientation phase) and prolonged loss of consciousness with characteristic neurological features (e.g., cerebral seizures with postictal state of confusion). Head-up tilt testing, introduced into clinical practice in 1986, is an efficient tool to diagnose neurocardiogenic syncope with comparatively high sensitivity in patients with recurrent syncope of unknown origin. Besides orthostatic training and pharmacotherapy, permanent dual-chamber cardiac pacing has gained increasing importance as treatment for cardioinhibitory forms of neurocardiogenic syncope.

Independent autonomic modulation of sinus node and ventricular myocardium in healthy young men during sleep.

INTRODUCTION: The aim of this study was to investigate whether autonomic modulation of ventricular repolarization may spontaneously differ from that of the sinoatrial node. METHODS AND RESULTS: Onset of P waves, QRS complexes, and the apex and end of T waves were detected beat to beat in high-resolution ECGs from nine healthy young men during the night. There were time-dependent fluctuations in the QT/RR slopes of consecutive 5-minute segments that could not be explained by the mean RR cycle length of the respective segment. Because the variability found in QT intervals could not be explained by either possible effects of rate dependence or hysteresis, autonomic effects were obvious. Power spectral analysis was performed for consecutive 5-minute segments of PP and QT tachograms. In a given subject, trends in the time course of low-frequency (LF) and high-frequency (HF) power in PP and QT often were similar, but they were quite different at other times. The mean LF/HF ratio for QTend (0.75 +/- 0.1) was different from that of PP (1.8 +/- 0.2; P = 0.002), indicating differences in sympathovagal balance at the different anatomic sites. Furthermore, at a given mean heart rate, averaged QT intervals were different on a time scale of several minutes to hours. The QT/RR slope of 5-minute segments correlated significantly with the HF power of QT variability but not with that of PP variability, indicating effects of the autonomic nervous system on ventricular action potential restitution. CONCLUSION: These differences demonstrate that changes in sinus node automaticity are not necessarily indicative of the autonomic control of ventricular myocardium.

Analog-digital recording of current and voltage during high voltage DC shocks.

UNLABELLED: Efficient on-line digitization is the prerequisite for computerized analysis of the electrical phenomena occurring during defibrillation. Conventional hardware presently provides only limited time resolution. The performance of various digitization rates for recording of voltage, current, and calculation of derived quantities like impedance, energy, and defibrillator capacitance was investigated. It was assessed both experimentally and by computer simulation of a trapezoidal discharge (of 9 msec duration into a constant resistive load of 50 omega with a defibrillator capacitance of 132 microF). The accuracy achieved with different digitization rates is given. For example, an accuracy of 1% for analog-digital conversion for impedance calculation during this kind of DC shock requires a sampling rate of 8 kHz without, and a rate of 1 kHz with linear interpolation to correct for the hardware dependent error due to sequential sampling. CONCLUSION: Highly efficient analog-digital conversion of delivered voltage and current during DC shocks is available within the limits of conventional inexpensive hardware.