[The interruption of atrioventricular conduction by cardiac fulguration in patients with supraventricular tachycardias. The mid- and long-term results]

Catheter ablation of the atrioventricular node is a therapeutic technique for the treatment of patients with drug-refractory supraventricular tachyarrhythmias. In our Arrhythmia Unit 25 patients (8 women, 17 men) aged (mean +/- DE) 56 +/- 10 years have undergone fulguration of the atrioventricular junction since 1986. The more frequent treated rhythm disturbance was atrial flutter or fibrillation, with uncontrolled rapid ventricular response. Absence of organic heart disease was diagnosed in 9 patients; the remainder had valvular heart disease (2), cor pulmonale (2), cardiomyopathy (7), hypertensive heart disease (2) and Wolff-Parkinson-White syndrome (3). Under general anesthesia 1.8 +/- 0.8 shocks/patients were delivered along 1.2 +/- 0.7 sessions/patient. In 23 of 25 patients (92%) complete atrioventricular block was achieved, and a pacemaker was implanted. There were no complications. The other 2 patients were referred to surgery for cryoablation of the atrioventricular junction. Patients were followed for an average of 21 +/- 12 months. Four patients have died: two due to congestive heart failure, which was present prior to the ablation procedure, the third because of a metastatic carcinoma, and the fourth had a sudden death 14 months after the procedure (he had dilated cardiomyopathy and Wolff-Parkinson-White syndrome). The remainder in chronic stable complete atrioventricular block are asymptomatic for arrhythmias and without antiarrhythmic medication.

Cardiac fulguration, a new alternative therapy for atrioventricular nodal reentrant tachycardia

Ten patients underwent endocardial catheter ablation of the atrioventricular junction for atrioventricular nodal reentrant tachycardias. Unipolar cathodic discharges at the distal electrode were administered against an external plate. Bipolar His and atrial deflections showed a mean of 0.15 mv and 0.5 mv respectively. Mean total energy used per patient was 195 J (range: 50-750), with a mean number of ablating discharges of 2.0 per patient, (range: 1-5). Complete atrioventricular block was achieved, but conduction reappeared in all except one patient, after a mean interval of 19.9 min. Electrophysiological evaluation was assessed 3-8 days after ablation. Sustained atrioventricular nodal reentrant tachycardias were no longer inducible in any patient. Retrograde conduction was abolished in six, and was slow and decremental in four. First-degree atrioventricular block, with intranodal delay was diagnosed in six, with an AH interval that ranged from 240 to 130 ms. Mean cycle length for appearance of Wenckebach atrioventricular block was 390 ms after ablation. One patient developed complete atrioventricular block after two discharges of 50 J, another required a repeat ablation for recurrence of intranodal tachycardia and also developed complete anterograde block in a new session of ablation with a 150 J discharge. In these two patients permanent pacing was needed. Eight patients were cured after a mean follow-up of 20 months. Less energy and fewer discharges should be administered to abolish functional dissociation of the atrioventricular node, without complete interruption of anterograde conduction.

Third-degree atrioventricular block in an athlete

There is a wide spectrum of changes in the resting electrocardiograms of athletes. We here present a case of third-degree atrioventricular block in an asymptomatic young athlete.

[Validation of the Holter method in detecting myocardial ischemia using an exercise test simultaneously]

To evaluate the reliability of Holter monitoring in reproducing myocardial ischemic changes, 110 patients (90 males, 20 females; age range: 14-74 years) underwent a Bruce protocol treadmill exercise test. An electrocardiogram was recorded simultaneously with a two-channel modulated Holter recorder (frequency response: 0.05-100 Hz) with bipolar CM-V3 and CM-V5 leads and by a conventional 12-lead system. An ischemic ST-segment change was defined as 1 mm or more ST-segment depression lasting more than 0.08 sec after the J point. Results were concordant in 101 patients, 36 with both positive and 65 with both negative responses. Eight false negative and one false positive Holter ischemic episodes occurred. This yielded an accuracy (expressed as sensitivity, specificity, positive and negative predictive values) of 81.8%, 98.5%, 97.3% and 89.0%, respectively. There was a good correlation between the maximal ST-segment depression (r = 0.57; p less than 0.001), duration of ischemia (r = 0.89; p less than 0.001), heart rate at the onset of the ischemic episode (r = 0.91; p less than 0.001) and maximal heart rate (r = 0.98; p less than 0.001).

CONCLUSIONS

Two-channel amplitude modulated Holter recording system with bipolar CM-V3 and CM-V5 leads can reliably reproduce ST-segment changes.

[Prognostic significance of silent ischemia in the exercise test in patients with coronary disease]

To evaluate the prognostic significance of silent ischemia during exercise testing, 152 consecutive patients (143 males, 9 females) with a mean SD of 55 +/- 7 years (age range 32-73) who underwent exercise testing and coronary arteriography within 3 months were studied. All patients had the following characteristics: 1) a positive electrocardiographic exercise test response; 2) significant coronary artery disease on the arteriography; 3) uninterrupted clinical follow-up for a minimum of 6 months. The 152 patients were divided in 2 groups: group I: 56 patients (37%) with ischemic ST-segment depression during exercise testing without angina (silent ischemia); group II: 96 patients (63%) with ischemic ST-segment depression and angina (symptomatic ischemia). Patients in group I and group II showed similar time to ST-segment depression (3.6 +/- 1.5 min vs 3.2 +/- 1.4 min; p = NS), maximal ST-segment depression and peak heart rate-systolic pressure product (21,151 +/- 7,124 vs 20,456 +/- 6,024; p = NS). Exercise duration was longer in group I than in group II (5.6 +/- 2.1 min vs 4.8 +/- 1.5 min; p less than 0.001). The extent of coronary artery disease defined by the number of significant narrowed coronary vessels, left ventricular end diastolic pressure and ejection fraction were similar in the 2 groups. Sixty six patients who underwent coronary bypass surgery were not included in the analysis. The remaining 86 patients (40 in group I and 46 in group II) were medically treated. The mean follow-up period was 43,5 +/- 25 months (range 6-101).2+ myocardial ischemia during exercise testing.

Dose related efficacy of adenosine triphosphate in spontaneous supraventricular tachyarrhythmias

Intravenous adenosine triphosphate has been proved to be useful for the treatment of supraventricular tachyarrhythmias. The optimal dose to be employed, however, has yet to be stated. Forty-two episodes of spontaneous paroxysmal supraventricular tachycardia, observed in 33 patients (16 men and 17 women, mean age 51 years) were treated with intravenous boluses. These were given in 10 mg increments at increasing doses from 10 to 50 mg at intervals of three minutes if the arrhythmia persisted despite the previous dose. When using a dose less than or equal to 40 mg, tachycardia was terminated in 37 of 42 episodes in less than 50 seconds. In four of the remaining five, atrial flutter and ectopic atrial tachycardia were diagnosed after administration of adenosine triphosphate. The other patient was subsequently found to have an atrioventricular reentrant tachycardia incorporating two accessory pathways. More than half of the treated episodes of supraventricular tachycardia terminated with the minimal dose of 10 mg and 7.1% required 40 mg. In five patients, arrhythmia ceased and reappeared despite the use of adenosine triphosphate. All the patients experienced an unpleasant feeling of dyspnoea or suffocation after injection of the drug. Sinus pauses and bradycardia following termination of the arrhythmia were directly correlated with the dose employed (P less than 0.05). We conclude that adenosine triphosphate is a useful, safe and effective drug at low dose in correctly diagnosed reentrant tachycardias involving the atrioventricular node. It is also useful as a diagnostic tool in patients with supraventricular tachyarrhythmias.

Thrombus apposition on catheter ablation injuries

64 ablation catheter-induced injuries were studied macroscopically and microscopically to determine the incidence of endocardial thrombus formation. Ablation was performed in 16 mongrel dogs, 7 days before necropsy, 16 endocardial necroses were located in the right atrioventricular (AV) junction, 16 in the non-coronary cusp of the aortic valve or the subaortic valve area, 16 in the right and 16 in the left ventricle. Cathodal discharge at the distal electrode was employed against an external anodal plate for ventricular ablation. Necroses in the right AV junction and in the aortic area where the result of transseptal His bundle ablation. Energies ranged from 100-360 J. Pathologic examination was performed 1 week after ablation. 13 thrombi were observed attached to the endocardial necrosis area, of sizes ranging from 1-25 mm diameter (mean 6.9 mm). Six thrombi were found in the septal valve of the tricuspid valve, two in the aortic valve, two in the subaortic region, and three related to ventricular necroses. We conclude that the incidence of thrombosis is 20% in ablation injuries, the majority, 77%, having a diameter less than or equal to 10 mm. No correlation was found between thrombus formation and delivered energy or catheter polarity.

[Cardiac fulguration. A healing treatment for intranodal re-entry tachycardias refractory to medication]

Six patients underwent fulguration of the AV junction for typical paroxysmal intranodal reentry tachycardias, refractory to medical treatment. Unipolar cathodic discharges at distal electrode were administered against an external plate. Bipolar His and atrial deflections showed mean values of 0.16 and 0.54 mv, respectively. Mean energy used was 233 J (range 50-750), with a mean number of 1.6 (range 1-3) discharges per patient. Complete AV block was achieved, but conduction reappeared in all, within a mean of 30 minutes. Electrophysiologic evaluation was assessed 3-8 days after ablation. Intranodal reentry tachycardias could not be initiated in any patient. Retrograde conduction was abolished in 3 patients, and in three it was slow and decremental. First degree AV block, with intranodal delay was diagnosed in 4 with a mean AH interval of 237 msec (range 190-300). Mean rate for appearance of Wenckebach AV block was 154 b/m. None of the patients required permanent pacing. Mean follow-up of the patients was 6.8 months. One of the patients required a new ablation for reappearance of intranodal tachycardia and CAVB was achieved in the second ablation. The other five remain asymptomatic. Intranodal reentry tachycardias can be cured by fulguration. Less energy and less discharges should be administered to abolish functional dissociation of the AV node, without complete interruption of anterograde conduction.

Amiodarone and hypokalemia. A dangerous combination

We describe the appearance of long QT interval and polymorphous ventricular tachycardia in a patient treated with amiodarone who presented with hypokalemia secondary to chronic diuretic therapy. Ventricular pacing was initiated upon admission. The hypokalemia was corrected and amiodarone was discontinued. After three days the patient showed a normal QT interval and was free of ventricular tachyarrhythmias. Although hypokalemia could itself have been the arrhythmogenic factor in this particular patient, the additional toxic effect of amiodarone cannot be ruled out. It seems reasonable to consider the combination of both as dangerous when we take into account that the majority of patients cited as having amiodarone-induced torsade de pointes had also potassium depletion.

Postnatal dependence of plasma copper and zinc levels on gestational age and maturity observed in infants fed a high zinc content formula

We studied the effect of gestational age and maturity on plasma zinc and copper levels at 10 and 120 days of age. The association of plasma zinc changes and body growth was also investigated. Infants were receiving a controlled intake of zinc and copper solely through a zinc-supplemented formula (4.7 mg/L of zinc and 0.16 mg/L of copper). Twenty-eight low-birthweight infants (less than 2,500 g) having gestational ages ranging from 33 to 40 weeks [17 with an appropriate birthweight for gestational age (AGA) and 11 small for gestational age (SGA)] were enrolled in the present study. Measurements of plasma zinc and copper concentration, weight, length, head circumference, and tricipital and subscapular skinfolds were carried out at 10 and 120 days of age. Proton-induced x-ray fluorescence technique (PIXE) was used to assess copper and zinc concentrations. At 10 days of age a significant correlation between copper concentration and gestational age was found. At 120 days of age the copper concentration was higher than at 10 days and independent of gestational age and maturity (mean +/- SEM = 116 +/- 5 micrograms/dl). At 10 days of age no significant correlation between zinc content and gestational age was found (86 +/- 4 micrograms/dl). The plasma zinc percent change over the period from 10 to 120 days of age was positively correlated with gestational age in the whole sample as well as in AGA and SGA infants separately.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between electrical and echocardiographic data in hypertrophic cardiomyopathy

We have studied 38 patients with clinical and echocardiographic evidence of hypertrophic cardiomyopathy. We tried to correlate the electrical findings of hypertrophy in electrocardiographic and vectorcardiographic tracings with the anatomical data supplied by M-mode echocardiography of septal and posterior wall thickness and left ventricular diameters.

Electrophysiologic study of patients with short P-R interval and normal QRS complex

In order to elucidate the electrophysiological nature of the short P-R interval we have studied 15 patients with this phenomenon and a normal QRS complex in the electrocardiogram; none of them had a history of arrhythmias. His bundle electrography and atrial stimulation were used to study the conductivity and refractory periods of the atrioventricular (AV) junction. In 13 cases the studies were repeated after the administration of verapamil. Baseline recordings showed a shortened A-H interval in 6 cases, a shortened H-V interval in 6 and in 3 more with a borderline H-V interval. During rapid atrial pacing A-H interval prolongation was abnormal in 10 cases that showed small increases or sudden prolongations at certain atrial rates. The effective nodal refractory period was shorter than normal. A double AV nodal pathway was demonstrated in one patient and another developed junctional reentrant tachycardias at fixed extrasystolic intervals. After verapamil the A-H interval increased in all but one patient. Significant changes were recorded for the AV nodal refractory periods. In the patient with dual AV nodal conduction verapamil prolonged conduction time and refractory periods through both pathways, and in the one with reentrant tachycardias upon atrial stimulation it abolished the tachycardia. In the presence of a normal QRS, a short P-R interval may be due to shortened conduction time through the AV node, and/or the His-Purkinje network. Our observations tend to rule out the presence of a complete bypass of nodal tissue. Despite the absence of a history of arrhythmias these patients may have electrophysiological abnormalities that predispose them to reentrant AV nodal tachycardias.

Jaccoud's arthropathy in patients with chronic rheumatic valvular heart disease

In a prospective study over a period of 3 yr, involving all patients with rheumatic valvular heart disease seen at our hospital, we found the diagnostic signs of Jaccoud's arthropathy in 17 of 400 cases (4.2%). All 17 patients had a past history of acute arthritis involving the joints and showed deformities at the time of diagnosis. The valvular lesions were mitral and aortic in 11 cases, mitral in 5 cases and aortic in 1 case. The most frequent joint deformities were: ulnar deviation at the metacarpo-phalangeal joints (12 cases), lateral deviation at the metatarso-phalangeal joints (12 cases), and hammer toe deformity (6 cases). The deformities were reducible in all of them. None of the patients had pain or signs of acute inflammation and functional capacity was normal. Other causes of joint deformity were ruled out by means of radiographic and serologic studies. Jaccoud's arthropathy is not a rare entity and its recognition is important for a differential diagnosis with chronic arthritis of other etiologies, also associated with valvular heart lesions.

[Retroperitoneal rupture of the duodenum caused by closed abdominal injury]

Preoperative diagnosis of retroperitoneal rupture of the duodenum is very difficult. Radiographical observation of air surrounding the right kidney or psoas muscle is of great assistance in this respect, but may only be expected in 30% of cases. Examination of the first segment of the digestive tract with the aid of "gastropgrafin" is advised. With the abdomen open, the presence of air, haematoma or bile in the transverse mesocolon or mesentery of the small intestine may be noted. In most cases, the breach can be closed with a double layer, leaving a drainage tube in the retroperitoneum. Measures than can be taken when suturing is unfeasable are also described.