[Allograft vasculopathy in the early phase of orthotopic heart transplantation: angiography, intravascular ultrasound and functional in vivo findings]

Accelerated graft coronary atherosclerosis disease is the main reason for long-term mortality and morbidity of heart transplant recipients. The aim of this in vivo study was to evaluate coronary atherosclerotic vessel abnormalities and endothelial function using angiography, intravascular ultrasound, and intracoronary acetylcholine infusion. Fourteen patients (11 male, 3 female; mean age 49.3 years) were examined early after heart transplantation (mean interval after transplantation: 11 weeks) because of coronary artery disease (n = 8), idiopathic dilatative cardiomyopathy (n = 7), mitral valve replacement (n: 1) or left atrial filiae of a leiomyosarcoma (n = 1). Mean age of the donor hearts (female n = 8) was 29 years; 3 patients received double- and 14 patients triple-immunosuppression. All patients underwent biplane ventriculography and coronary angiography; a total of 120 coronary segments (main stem 21, left anterior descending artery 85, circumflex artery 14) was examined by intravascular ultrasound (20 MHz, 3.5 F catheters). In 13 patients, acetylcholine was infused into the proximal left anterior descending artery (0.15 microgram/min to 150.0 micrograms/min) to evaluate vasomotion within this segment. Ventriculography demonstrated regional wall abnormalities in 2 patients, angiography revealed 9 noncritical stenotic segments in 5 patients. Intravascular ultrasound detected 52 cross-sectional areas with a three-layer appearance indicating intimal thickening. Mean circumferential expansion of intimal proliferation was 192 degrees and mean intimal thickness was 0.35 mm. Only 5 segments of the sonographically pathological cross-sectional areas showed angiographic evidence of atherosclerotic lesions. After intracoronary infusion at a lower dose (0.15 and 1.5 micrograms/min) of acetylcholine, vasoconstriction was observed in 2 patients, at a dose of 15.0 and 150.0 micrograms/min in 10 patients. This response to acetylcholine did not depend on the intravascular or angiographical extent of atherosclerotic vessel abnormalities. In heart transplant recipients, coronary artery abnormalities can already be depicted at an early stage using intravascular ultrasound. The majority of patients show coronary vasoconstriction following infusion of acetylcholine at a higher dose. Further investigation is necessary to clarify whether the depicted vessel wall abnormalities can already be interpreted as newly developed graft atherosclerosis and whether abnormal vasomotion after acetylcholine is indicative of endothelial dysfunction.

Value of intravascular ultrasound in the diagnosis and characterization of patent ductus arteriosus in an adult patient

We report the case of a 47-year-old patient with a patent ductus arteriosus who underwent angiography and percutaneous intravascular ultrasound examination. The case illustrates that intravascular ultrasound contributes to the characterization of patent ductus arteriosus when a surgical or trans-catheter closure is planned, as calcifications of the wall as well as aneurysmal dilatations can be ruled out. Furthermore, measurements of the diameter of the ductus can be made.

[Reproducibility of the signal-averaged, high-pass filtered electrocardiogram]

In order to test the reproducibility of the signal-averaged electrocardiogram (SAECG) using Simson's method (high-pass filter cutoff frequency 25 Hz, orthogonal leads, recording of 133 s per lead), 121 patients were examined. In all patients, two signal-averaged ECGs were performed on the first day of the study immediately after each other, using identical electrode position. In a subgroup of 47 patients, the same procedure was repeated 3 days later. There was no difference between the mean values of conventionally calculated averaging parameters (heart rate, QRS-duration, root-mean-square voltage in the terminal 40 ms of the highly amplified and filtered QRS-complex [V40], the low amplitude signal duration under 40 microV in the terminal portion of the QRS-complex [LAS], total root-mean-square voltage of the QRS-complex), both with regard to immediate and short-term reproducibility. Thus, conventionally calculated averaging parameters are well reproducible.

[Detection of pacemaker electrode infection using intravascular ultrasound]

The case of a 60-year-old man who developed fever 14 months after last implantation of a DDD pacemaker system is reported. Though staphylococcus epidermidis could be identified in several blood cultures, transthoracic and transesophageal echocardiograms and scintigraphy with antibodies to human leucocytes could not identify any focus of infection. The percutaneous intravascular and intracavitary ultrasound examination clearly demonstrated a vegetation within the subclavian vein, being attached to the ventricular lead; within that segment of the vein the atrial lead showed a small hyperdense structure. Further vegetations along the leads within the right atrium and ventricle could be ruled out. Subsequent removal of the pacemaker system caused resolution of the signs of inflammation.

Radiofrequency ablation of accessory pathways: characteristics of transiently and permanently effective pulses

The purpose of this study was to characterize and compare the radiofrequency current applications that produced permanent or transient accessory pathway conduction block. One hundred fifty-two radiofrequency energy applications that induced permanent (permanently effective pulses, n = 48) or transient (transiently effective pulses, n = 104) accessory pathway block in 57 patients with 60 accessory pathways were analyzed. The time from the onset of current application to disappearance of preexcitation or termination of supraventricular tachycardia by permanently effective pulses was 1-15 seconds (mean 3.6 +/- 3.8 sec) compared to 2-29 seconds (mean 11.5 +/- 7.5 sec) by transiently effective pulses (P less than 0.01). After transiently effective pulses that induced block in accessory pathway, conduction resumed within 5 minutes while induced block by permanently effective pulses persisted in 44 of 48 patients (92%) during follow-up of 11 +/- 12 months. The accessory pathway conduction returned in the remaining four patients after ablation 2 weeks to 7 months. After transiently effective pulses, 41 impulses were delivered to the same site using a higher power output (n = 32) and/or longer energy delivery duration (n = 20) without new mapping of accessory pathway location. Thirty-six of these impulses again resulted in transient accessory pathway block, four had no effect, only one impulse induced a permanent block in the accessory pathway. Pulses with higher power outputs tended to induce transient effects more frequently than pulses with lower energy.(ABSTRACT TRUNCATED AT 250 WORDS)

[Catheter ablation of ventricular tachycardia]

Catheter ablation of ventricular tachycardias was performed in a total of 80 patients whose tachycardias were considered as drug refractory and who were not considered to be candidates for antitachycardic surgery or implantation of an automatic cardioverter defibrillator. After careful endocardial catheter mapping including pacing interventions, either direct-current (DC) (n = 61) or radiofrequency current (RF) (n = 13) or both (n = 6) were applied of the "site of origin" of ventricular tachycardia or the "zone of slow conduction". 42 of 51 patients with coronary heart disease were discharged; ventricular tachycardia recurred in 8 cases, and 2 patients died suddenly. In the remaining 32 patients, there were no recurrences of ventricular tachycardia during a mean follow-up period of 12 month. Three patients died perioperatively. In 21 of 29 patients without coronary artery disease, no recurrences of ventricular tachycardia were observed (mean duration of follow-up 17 months) whereas 8 cases had a recurrence of ventricular tachycardia.

Relation between ventricular late endocardial activity during intraoperative endocardial mapping and low-amplitude signals within the terminal QRS complex on the signal-averaged surface electrocardiogram

Noninvasive recording of ventricular late potentials and intraoperative endocardial mapping at 36 sites were performed in 24 patients with left ventricular aneurysm and drug-resistant sustained ventricular tachycardia due to coronary artery disease. Their mean age was 55 +/- 8 years. Mean ejection fraction was 28 +/- 12%. For detection of late potentials on the signal-averaged QRS complex, 3 different algorithms were used. Late potentials were found in 54, 67 and 67% of the patients, respectively. In patients with a late potential on the signal-averaged electrocardiogram (ECG), delayed local activation (greater than 40 ms beyond the QRS complex on the intraoperative surface ECG) was recorded at 5.5, 5.5 and 5.6 endocardial sites. In patients without a late potential, this type of delayed local activation was detected at 2.4, 1.1 and 0.9 of 36 endocardial sites, respectively (p less than 0.05; p less than 0.01; p less than 0.002). The mean delay of local endocardial activity was 38, 35 and 37 ms in patients with a late potential on the body surface recording versus 20, 19 and 11 ms, respectively, in patients without a late potential (p less than 0.05; p less than 0.05; p less than 0.002). There was no correlation between the duration or amplitude of the late potential, if present, and the number of endocardial sites exhibiting delayed activity (r = -0.23, r = -0.05, r = 0.21; correlation not significant for each) or the mean duration of the endocardial delayed activity (r = -0.25, r = -0.14, r = -0.07; correlation not significant for each). These results indicate that the presence of late potentials on the signal-averaged surface ECG is related to the mean duration of endocardial late activity as well as to the number of endocardial sites exhibiting a given degree of delayed activation. Thus, it is dependent on the mass of slowly activated tissue. However, a direct conclusion from the duration or the amplitude of a late potential to the amount of delayed activation or the extent of endocardial time delay does not seem possible.

[Catheter ablation in ventricular tachycardia]

The basis for management of ventricular tachycardia (VT) is pharmacologic treatment which is effective, however, in only about 20 to 30% of the patients. With respect to this problem, alternative therapeutic modes have been developed which include, in addition to antitachycardia stimulation, electrical, palliative therapy such as the implantable automatic defibrillator, definitive measures such as map-guided antitachycardia surgery and catheter ablation. The goal of catheter ablation is the selective destruction of heart structures which are the morphologic correlate for initiation of propagation of VT. Catheter ablation was discovered by chance by Fontaine after a defibrillation during an electrophysiologic study in which a defibrillating electrode in the proximity of a catheter at the His bundle induced complete AV-block. This effect of destruction in the AV-conduction system by direct current as a therapeutic measure was further developed by Gallagher and Scheinman. The mechanism held responsible is coagulation by the electrode of neighboring tissue and barotrauma. The technique, which was initially used for ablation of the His bundle in supraventricular tachycardia, can also be used for ablation of accessory pathways or the site of origin of VT which generally lies endocardially in marginal regions of myocardial infarctions. CATHETER MAPPING: In sinus rhythm and induced VT, endocavity catheter mapping is carried out after heparinization with electrocardiograms recorded from at least six to ten sites in the right and left ventricles. At the site of early activation, detailed mapping is used for identification of the site of earliest activation, then pace-mapping is performed during sinus rhythm and VT. The morphology of the stimulated QRS complexes is compared with that of the spontaneous VT. In patients in whom VT cannot be induced, localization is carried out by pace-mapping alone. CATHETER ABLATION: After localization, in intubation narcosis and with continuously monitored arterial blood pressure, the suspected site of origin of the VT is subjected to an initial shock during sinus rhythm by means of a distal electrode of a catheter in stable contact with the endocardium. For mapping and ablation, the same catheter is used. After each subsequent shock, assessment is performed to determine if the distal electrode pair still conducts local ventricular signals and if ventricular stimulation is possible. The shock energy delivered is 100, 200 or 400 Joules. At the time of shock discharge, the remaining electrodes or catheters are disconnected. In the case of bradycardia or tachycardia after the shock, immediate connection to an external stimulation generator is established. At the time of the shocks, relaxation is provided by succinylcholine. All shocks are delivered from the anode. The integrity of the catheter is tested after each shock, no catheter is used more than three or four times. At the earliest, ten minutes after shock delivery, induction of clinical VT is attempted with programmed stimulation and if induction is possible, at the same site a maximum of two more shocks are delivered or, after renewed mapping, another shock is delivered to a different site. Induced non-clinical VT is not subjected to ablation.(ABSTRACT TRUNCATED AT 400 WORDS)

[Behavior of ventricular late potentials following catheter ablation of ventricular tachycardia]

In 10 patients non-invasively recorded signal-averaged electrocardiograms were obtained before and after direct-current ablation of ventricular tachycardia (right ventricular origin n = 5; left ventricular origin n = 5). The algorithms proposed by Simson and Karbenn et al. were used (modified Frank leads, high-pass filter cut-off frequency 25 Hz). No differences were observed between the mean values of the duration of the QRS-complex, the mean voltage during the last 40 ms of the QRS-complex, the duration of the late potentials and the number of patients having late potentials before and after ablation, respectively. The success of ablation could not be predicted by the signal-averaged ECG. There was no difference between the averaging parameters of those patients without recurrences of ventricular tachycardia during the follow-up period and those with (n = 3). Thus, the signal-averaged ECG did not prove helpful in predicting a successful outcome of direct-current catheter ablation of ventricular tachycardia.

Effects of non-pharmacological interventions on ventricular late potentials

The purpose of the paper is to review the presently available information of the effects of non-pharmacological interventions for the control of drug-refractory ventricular tachyarrhythmias on non-invasively recorded ventricular late potentials. During recent years, non-pharmacological interventions have evolved as an alternative form of treatment to control drug-refractory ventricular tachyarrhythmias. The effects of these non-pharmacological measures on ventricular late potentials are poorly understood. Successful surgical control of ventricular tachycardia often normalizes the signal averaged ECG and may eliminate delayed potentials. Thus, this non-invasive test may be useful in assessing surgical efficacy in subgroups of patients with ventricular tachycardia. However, the clinical value of late potentials in assessing surgical efficacy in the individual case may be limited as the sensitivity and specificity of the loss of late potentials after antitachycardia surgery are low. In addition, the effects of transvenous catheter ablation on ventricular late potentials will be reviewed. The available information suggests that this intervention has little effects on the presence or absence of late potentials. Thus, non-invasive recording of late potentials seems not to be helpful in predicting the acute and long-term efficacy of catheter ablation. In conclusion, changing of the parameters in the signal-averaged QRS complex after antitachycardia surgery may be useful in predicting the efficacy of surgical interventions for drug-refractory ventricular tachycardias in subgroups of patients. However, the sensitivity and predictive accuracy of this test are low, thus limiting its clinical usefulness.

Effects of pharmacological and non-pharmacological interventions on ventricular late potentials

The purpose of this paper is to review the presently available information on the effect of antiarrhythmic drugs and of map-guided antitachycardia surgery on ventricular late potentials. Studies in experimental myocardial infarction have shown that antiarrhythmic drugs are able to prolong regional low-amplitude fractionated electrical activity. However, no correlation between changes in duration of low-amplitude electrical activity and antiarrhythmic drug efficacy could be demonstrated. A similar lack of correlation between changes in duration of late potentials as recorded by the signal averaging technique from the body surface and inducibility or suppression of ventricular tachycardia were observed. Neither changes in duration or amplitude nor in the frequency content of ventricular late potentials showed an unequivocal correlation with drug efficacy. By contrast, there is convincing evidence that exclusion of arrhythmogenic tissue by map-guided antitachycardia surgery correlates with the loss of late potentials postoperatively in a high percentage of cases. If, however, late potentials persist after surgery, there is a high chance of ventricular tachycardia being still inducible postoperatively. A loss of ventricular late potentials by surgery may be the result of isolation of the arrhythmogenic tissue, devitalization and/or removal. In conclusion, there is presently no convincing evidence that any of the parameters for characterization of ventricular late potentials is clinically useful to predict the efficacy of antiarrhythmic drug therapy. On the other hand, ventricular late potentials have proved useful for prediction of the success of map-guided antitachycardia surgery.

[Therapy of refractory ventricular tachycardia by transvenous electrical ablation]

In 6 patients (mean age 49 +/- 11 years) with chronic recurrent ventricular tachycardia which were relatively slow during antiarrhythmic therapy and had been proven to be resistant to various antiarrhythmic drugs, catheter ablation of the site of origin of ventricular tachycardia was performed after endocardial activation and/or pace-mapping. According to the results of catheter mapping, the sites of origin of ventricular tachycardia were in the region of the infero-lateral wall (n = 3), in the anterolateral wall (n = 1) and in the right ventricle (n = 2). In 3 cases, two ablative procedures were performed as the first was only transiently successful. A total of 51 shocks was delivered (200 J 45 times, 100 J 5 times and 400 J once). The following complications were observed: multiple episodes of spontaneous, partly polymorphous ventricular tachycardia which degenerated into ventricular flutter on several episodes (n = 1); transient third degree AV-block and intermittent complete right bundle branch block (n = 1); transient ST-elevation (n = 3); and self-terminating atrial tachycardia lasting for several minutes (n = 1). Immediately after the first ablative procedure, either no ventricular tachycardia could be induced any longer (n = 2) or non-clinical ventricular tachycardia was induced (n = 2). In the remaining 2 patients, programmed ventricular stimulation was not repeated immediately at the end of the ablative procedure. During a follow-up study at the end of the first week, the clinical ventricular tachycardia could be induced again in 3 of 4 cases. In 3 cases, a second ablative procedure was performed because of recurrences of ventricular tachycardia (n = 2) or syncope (n = 1). During final follow-up (mean 4.3 +/- 3.4 months), no recurrences of ventricular tachycardia were observed in 5 cases. In one case, recurrences occurred. Therefore, an automatic cardioverter was implanted. In conclusion, these preliminary results show that catheter ablation of drug-resistant ventricular tachycardia is feasible and may be an alternative to surgical procedures.

Methods for non-invasive detection of ventricular late potentials--a comparative multicenter study

To evaluate the methodological problems of the non-invasive registration of late potentials the results obtained with four different averaging devices in the same 109 patients were compared. The high-resolution ECG was obtained from the body surface, high-gain amplified and filtered. With the averaging technique, the improved signal-to-noise ratio was able to detect low-amplitude cardiac activity. The incidence of late potentials detected with the four averaging systems, whose characteristics are described, ranged between 12% and 21%. Corresponding positive results were obtained in 5.5%, corresponding negative results in 68.8%. The reasons for differing results were mainly due to differences in visual or automatic interpretation of the registered fractionated electrical cardiac activity. Additionally, the determination of the end of QRS using the QRS width, obtained from reference leads, may influence the specificity of the methods.

Automatic identification of late potentials

The purpose of the present study was to develop an algorithm for the automated identification of ventricular late potentials (LP) that can be recorded non-invasively by means of the signal averaging technique. This new algorithm was designed to determine the possible presence and the onset and duration of a given LP by analyzing the end of the QRS complex. As there is no objective standard for identifying these late potentials, the new algorithm was developed by continuous comparison and adaptation to visual analysis in 65 patients (algorithm definition phase). In the subsequent trial phase, visual and automated analysis were compared in a second cohort of 50 patients (40 patients with and 10 patients without late potentials). In the latter 50 patients, the results obtained with the new algorithm corresponded to the analysis made by at least two of three independent observers in 92% of cases. In only four patients--one without and three with late potentials--there was no agreement between the observers and the new program. In conclusion, the new algorithm can be used reliably for the evaluation of late potentials. The results are more objective. They are reproducible, which is of great advantage when data from different groups are to be compared or when less experienced investigators are using non-invasive methods for registration of late potentials.

Effects of antiarrhythmic surgery on late ventricular potentials recorded by precordial signal averaging in patients with ventricular tachycardia

In seven patients with documented ventricular tachycardia (VT) and prior myocardial infarction, late potentials (LP) were recorded at the end of or after the QRS complex from the body surface using high-gain amplification and the signal averaging technique (RC filter settings 100 to 300 Hz). In 6 to 7 patients VT could be initiated by programmed right ventricular stimulation; in one case, VT was inducible only from the left ventricle during surgery. Surgery was guided by epi- and endocardial mapping. In most cases besides resection of scar tissue, a partial or complete subendocardial encircling ventriculotomy was performed. Postoperatively, LPs were abolished in five cases, VT being no longer inducible. In the remaining two patients, LPs were still present. VT was still inducible in one of these two cases whereas in the other case, no programmed testing was done postoperatively. These data suggest that the abolition of LPs by surgery is closely related to the disappearance of the propensity to stimulus-induced VT. Thus, the averaging technique represents a new approach to the noninvasive control of the efficacy of surgery in patients with VT and prior myocardial infarction.

[Response of ventricular late potentials after surgical therapy of ventricular tachycardia]

19 patients with either previously documented sustained ventricular tachycardia (VT) (n = 16) or only inducible VT (n = 3, one of whom had recurrent syncope), due to previous myocardial infarction were studied pre- and postoperatively. Mean age was 53 +/- 6 years, 16 were male, 3 female. In all but one, VT could be induced preoperatively by programmed right ventricular stimulation. Late potentials (LP) were recorded at the end of or after the QRS-complex from the body surface using high-gain amplification and the signal averaging technique (RC-filter settings 100 to 300 Hz). Indication for surgery was either intractable VT or bypass grafting and/or aneurysmectomy. Preoperatively, mean duration of late potentials was 54 +/- 37.7 ms, mean amplitude was 12 +/- 14.0 mean V. Surgery was guided by epi- and endocardial mapping. In 14 cases endomyocardial encircling ventriculotomy was the main procedure, whereas in 5 patients only aneurysmectomy and bypass grafting were performed. Postoperatively, late potentials were no longer detectable in 12 cases, whereas in 6 of 7 cases there was a decrease in duration, but no essential change in amplitude. A postoperative electrophysiological study was performed in 18 cases. In those 12 patients with abolition of LPs, the maximal number of inducible ventricular echo beats using an extended stimulation program from three right ventricular sites, ranged between 1 and 5 in 9 cases, between 10 and 11 VE in 2 cases, whereas VT was induced in only 1 case. In 6 patients in whom LPs were still detectable, ventricular tachycardia could still be induced in 2 cases and a maximal response of ten echo beats was observed in another patient. Abolition of LP by surgery is closely related to the disappearance of the propensity to stimulus-induced VT. Thus the averaging technique may provide a non-invasive procedure to assess the successful outcome after operation for ventricular tachycardia. If, however, LPs are still present, this does not exclude successful surgical abolition of the propensity to ventricular tachycardia.

Prevalence of late potentials in patients with and without ventricular tachycardia: correlation with angiographic findings

Late potentials occurring at the end of or after the QRS complex were searched for from the body surface using high gain amplification and signal averaging techniques with filter settings between 100 and 300 hertz. The number of repetitions of the averaging process ranged between 150 and 300. Two hundred thirty-six patients were studied. In 27 control subjects, no late potentials were recorded. Among 146 patients without ventricular tachycardia or fibrillation, late potentials were present in 49 (34 percent). The mean duration of late potentials was 31 +/- 15.3 ms (median 25). Of 63 patients with documented ventricular tachycardia or fibrillation, 45 (71 percent) had late potentials (mean duration 51 +/- 31.5 ms; median 50) (probability [p] greater than 0.001). There was a close correlation between the detection of late potentials and left ventricular function. Late potentials occurred more frequently in patients with than in those without ventricular akinesia or aneurysm and in patients with than in those without ventricular tachycardia or fibrillation. In conclusion, late potentials are a frequent finding in patients with regional contraction abnormalities, both in patients with and in those without documented ventricular tachycardia. The greater prevalence and longer duration of these signals in patients with ventricular tachycardia or fibrillation might be responsible for the greater susceptibility to ventricular tachycardia. Long-term follow-up studies will be necessary to assess the possible prognostic significance of late potentials in patients without previously documented ventricular tachycardia or fibrillation.