Günter Steurer

The differential diagnosis of a regular tachycardia with a wide QRS complex on the 12-lead ECG: ventricular tachycardia, supraventricular tachycardia with aberrant intraventricular conduction, and supraventricular tachycardia with anterograde conduction over an accessory pathway.

The differential diagnosis of a regular tachycardia with a wide QRS complex on the 12-lead electrocardiogram (ECG) remains an important challenge. Three different types of mechanisms can produce such an arrhythmia: (1) a supraventricular tachycardia with intraventricular aberrant conduction; (2) a supraventricular tachycardia conducting to tbe ventricles over an accessory pathway; and (3} a ventricular tachycardia. After an analysis of the limitations of the diagnostic criteria, we recently proposed new criteria for the differential diagnosis between intraventricular aberrant conduction and ventricular tachycardia. These criteria are reviewed here and new criteria are presented to recognize a tachycardia conducting anterogradely to the ventricles over an accessory pathway. As far as we know, this is the first systematic attempt to electrocardiographically differentiate this last arrhythmia from ventricular tachycardia.

Radiofrequency Ablation of Symptomatic but Benign Ventricular Arrhythmias

GURSOY, S., et al.: Radiofrequency Ablation of Symptomatic but Benign Ventricular Arrhythmias. Two cases are presented where ablation of severely symptomatic ventricular arrhythmias not responding to medical therapy was accomplished with radiofrequency current application. After a routine programmed stimulation protocol, a quadripolar ablation catheter with a 4‐mm tip was advanced percutaneously into the left ventricle in one case and into the right ventricle in the second case; and after precise pace mapping, the arrhythmogenic focus was successfully ablated using radiofrequency current. The postablation ambulatory recording revealed virtual eradication of ventricular ectopy in both cases. In conclusion, in severely symptomatic cases of “benign” ventricular arrhythmias, radiofrequency ablation offers an effective therapeutic alternative.

Right‐Sided Versus Left‐Sided Radiofrequency Ablation of the His Bundle

Radiofrequency (RFJ ablation of the His bundle was attempted in 30 consecutive patients with atrial flutter or fibrillation. A 7 French quadripolar catheter with a 4‐mm distal electrode was advanced from the right femoral vein (21 patients), or subclavian vein (two patients) and positioned across the tricuspid valve. Adequate His‐bundle potentials were obtained in all patients. However, in six patients atrioventricular (AV) block could not be obtained after multiple (mean = 8) applications of RF energy from the conventional right‐sided approach. In these patients the same catheter was advanced to record a His potential through a retrograde arterial approach. AV block was created in all patients with one to three applications of RF energy. The duration of the procedure was 22 to 90 minutes for the right‐sided approach and 5 to 10 for the left‐sided approach (P < 0.005). Subsequently, in seven patients a left‐sided approach was used first. One to six applications of RF energy were required to create AV block. The radiation exposure time was 3 to 20 minutes. No complications occurred. Conclusions: RF ablation of the His bundle seems easier using a left‐sided than a right‐sided approach, reduces procedure and radiation time, and avoids recovery of conduction. These data suggest that a left‐sided approach, in spite of requiring arterial catheterization, may be preferable to a right‐sided approach.

Heart Rate Variability in Isolated Rabbit Hearts

The presence of heart rate variability (HRV) in patients with cardiac denervation after heart transplantation raised our interest in HRV of isolated, denervated hearts. Hearts from seven adult white ELCO rabbits were transferred to a perfusion apparatus. All hearts were perfused in the working mode and in the Langendorff mode for 20 minutes each. HRV was analyzed in the frequency domain. A computer simulated test ECG at a constant rate of 2 Hz was used for error estimation of the system. In the isolated, denervated heart, HRV was of random, broadband fluctuations, different from the well‐characterized oscillations at specific frequencies in intact animals. Mean NN was 423 ± 51 ms in the Langendorff mode, 406 ± 33 ms in the working heart mode, and 500 ms in the test ECG. Total power was 663 ± 207 ms2, 817 ± 318 ms2, and 3.7 ms2, respectively. There was no significant difference in any measure of HRV between Langendorff and working heart modes. The data provide evidence for the presence of HRV in isolated, denervated rabbit hearts. Left atrial and ventricular filling, i.e., the working heart mode, did not alter HRV, indicating that left atrial or ventricular stretch did not influence the sinus nodal discharge rate.

Cardiac depolarization and repolarization in Wolff-Parkinson-White syndrome.

Delta wave and QRS complex polarities have been extensively studied in preexcitation syndromes. However, only limited data exist about ventricular depolarization and repolarization in the setting of maximal preexcitation in relation to the site of insertion of the accessory pathway. Therefore this study was designed to systematically analyze cardiac depolarization and repolarization in patients with maximal preexcitation. We analyzed the polarity of the QRS complex and T wave on the frontal plane on the conventional 12-lead electrocardiogram in 118 patients with maximal preexcitation. Fast atrial pacing was used to provoke maximal ventricular preexcitation. The 32 patients with a left lateral accessory pathway showed right-axis deviation of the QRS complex (110 +/- 20 degrees) with a left-axis deviation of the T-wave axis (-40 +/- 25 degrees). The 54 patients with a posteroseptal accessory pathway had a left axis of the QRS complex (-50 +/- 20 degrees) with a right-axis deviation of the T-wave axis (95 +/- 15 degrees). The 11 patients with a right lateral accessory pathway had a left axis of the QRS complex (-40 +/- 20 degrees) and a right axis of the T wave (110 +/- 10 degrees). In 7 patients with a left anterolateral accessory pathway and 14 patients with a right anteroseptal accessory pathway, the axis of the QRS complex was 50 +/- 25 degrees and 45 +/- 20 degrees, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Early-Onset Thrombocytopenia During Combination (Chemotherapy in Testicular Cancer is Induced by Vinblastine

Platelet kinetics were studied in 70 patients with testicular cancer to elicit the agent responsible for chemotherapy‐induced transient early‐onset thrombocytopenia; 204 treatment courses were analyzed using three different therapy protocols, which contained vinblastine and bleomycin either alone or in combination with cisplatin. Platelet count decreased significantly from the start of vinblastine administration reaching its nadir on the third day of therapy in each of the three treatment groups. Between day 4 and day 10 of the treatment cycle, platelet counts steadily increased even in patients still receiving continuous bleomycin infusions. The conclusion that the observed early‐onset thrombocytopenia was caused by vinblastine was substantiated by the outcome of two additional examinations. Platelet half‐life was significantly shortened 24 hours after vinblastine administration and electron microscopy revealed a dissolution of cytoplasmatic microtubules with loss of the typical discoid shape of platelets within 15 minutes after the start of therapy. Both findings occurred irrespective of the specific treatment protocol, i.e., even after nothing but vinblastine had been given. These results strongly suggest that vinblastine is the main cytostatic agent responsible for the transient early‐onset thrombocytopenia observed during chemotherapy of testicular cancer.

Bedside recordings of His-bundle electrograms using conventional twelve-lead surface electrocardiography.

Bedside Recording of His Potentials. Introduction: Endocavitary His‐bundle electro‐grams are usually recorded using high fidelity amplifiers and special filters.

Antiadrenergic cardiovascular adverse effects of high-dose amiodarone loading regimen

A 55-year-old patient with inferior wall infarction was treated effectively for ventricular tachycardia with high-dose oral amiodarone loading regimen (5 g within 16 hours). Serial pharmacokinetic studies demonstrated a rapid temporary increase in amiodarone plasma concentration to a maximum of 3.40 micrograms/ml 17 hours after initiation of therapy followed by a return to normal plasma concentration within 8 hours. During fast drug evasion the patient developed acute low-output syndrome with syncope successfully controlled with intravenous catecholamine administration. Our findings suggest that the cardiovascular collapse was caused by the non-competitive adrenoceptor antagonism of amiodarone resulting in secondary autonomic insufficiency.

Surgical treatment of cardiac arrhythmias. The physician’s point of view

The present therapeutic armentarium for the management of cardiovascular disease is enormous. We have at our disposal many pharmacologic and nonpharmacologic means to diminish or relieve ischemia, improve mechanical function of the heart, and to prevent or terminate an acute episode of cardiac arrhythmia. There are not, however, many cardiovascular diseases which can be truly cured. ‘Cure’ means the total suppression of symptoms, no need for any additional treatment, return of life expectancy to normal and an improvement in quality of life to such an extent that the patient can really forget that he (she) was ever ill.