Atrioventricular node modification in patients with chronic atrial fibrillation: role of morphology of RR interval variation.

BACKGROUND: This study evaluates the role of RR interval distribution pattern as an outcome predictor of radiofrequency (RF) modification of atrioventricular (AV) node in chronic atrial fibrillation (AF) and attempts to elucidate the likely mechanism of rate control. METHODS AND RESULTS: Sixty-five patients with chronic AF underwent AV node modification. The RR interval distribution pattern was derived from 24-hour ECG recordings obtained before and after the procedure. The preablation pattern was bimodal (B) in 36 patients (55%) and unimodal (U) in 29 patients (45%). After the modification procedure, the B pattern shifted to U (78%) or became modified B (22%). The mean number of RF pulses delivered and the fluoroscopy time were n=8+/-5 and 24+/-11 minutes, respectively, in patients with B pattern versus n=18+/-7 and 45+/-17 minutes in patients with U pattern (P<0.001 for both). The location of successful ablation was posteroseptal and lower midseptal in 26 patients (81%) with B pattern versus 2 (13%) with U pattern (P<0.001). Mean and maximal ventricular rates and heart rate at peak exercise were reduced after the procedure in both groups (P<0.001 for all). Long-term success rate, AV block incidence, and pacemaker implantation rate were 89%, 0%, and 8%, respectively, in patients with B pattern versus 52% (P<0.001), 21% (P=0.006), and 48% (P<0.001) in patients with U pattern. CONCLUSIONS: RF modification of the AV node is expected to be more effective, safe, and expeditious in patients with chronic AF and B RR interval distribution pattern. Posterior atrionodal input ablation may be the prevailing mechanism of rate control in these patients, whereas U-pattern patients may benefit from partial injury to the AV node.

A noninvasive method for the detection of dual atrioventricular node physiology in chronic atrial fibrillation.

Considering the electrophysiologic study as a reference, the RR interval distribution analysis is a sensitive (88%) and specific (80%) noninvasive method for detecting dual atrioventricular (AV) node physiology. This method may prove useful in selecting patients with atrial fibrillation who are considered appropriate candidates for radiofrequency modification of AV nodal conduction as opposed to AV nodal ablation.

Sealing of coronary artery aneurysm by using a new stent graft.

Coronary stenting has begun to play an increasingly important role in the management of coronary artery aneurysms. A case of successful and complete sealing of a coronary aneurysm by using a new stent graft is described. Further studies in a large patient population are required to confirm the safety and efficacy of this method. Cathet. Cardiovasc. Intervent. 48:96-99, 1999.

Intracoronary stent placement proximal to a myocardial bridge: immediate and long-term results.

The intracoronary stent placement in a lesion proximal to a myocardial bridge is of special importance and is considered to be a challenge for the interventional cardiologist. In this study 4 cases of stent implantation proximal to a coronary bridged segment are described. In all cases complications were observed after the procedure. The patients remained free of symptoms and the exercise TI201 test was negative for ischemia 8.5+/-2.6 months later. Although there is skepticism because of the abnormal coronary flow pattern, the endothelial dysfunction and the subsequent thrombogenicity, the stent placement proximal to a myocardial bridge was safe and with favorable long term results in all 4 cases. However, further studies in large populations are necessary.

Elective intracoronary Micro-Stent II implantation without quantitative coronary angiography or intravascular ultrasound guidance and without subsequent anticoagulation: short- and long-term results.

Intracoronary stenting has been shown to reduce acute closure and restenosis rate in patients treated with coronary angioplasty. The use of high inflation pressures and intravascular ultrasound guidance allowed the substitution of anticoagulants with antiplatelet agents but increased the cost. The aim of this study was to investigate the effectiveness, safety, and long-term outcome of the elective implantation of a relatively new type of stent (Micro-Stent II), without the use of quantitative coronary angiography or intravascular ultrasound guidance and without subsequent anticoagulation. The study included 361 patients who underwent elective microstent implantation. Stent expansion was performed at 8 atm followed by higher inflation pressure at 14-20 atm. Heparin was given intraarterially only once immediately after the arterial sheath insertion. Ticlopidine was started at least 48 hours before the procedure and continued for 1 month while aspirin was continued indefinitely. All patients were followed up for 12.9 +/- 3.6 months. Short term outcome (first month): Stent implantation was successfully achieved in 361 of 366 patients (98.6%). Seven patients (1.9%) were excluded from the study and received anticoagulants because of a suboptimal result. In total, 423 stents were implanted. There was no subacute thrombosis, but acute vessel closure occurred in one patient (0.3%). Non-Q wave myocardial infarction occurred in six patients (1.7%), Q wave myocardial infarction occurred in one patient (0.3%), and only one death (0.3%) of nonischemic origin was reported. No major peripheral vascular complications were observed. Late results: Q or non-Q wave infarction occurred in 13 patients (3.6%), 26 patients (7.2%) underwent a repeat angioplasty, eight patients (2.2%) underwent coronary artery bypass grafting, and four patients (1.1%) died. Overall, 284 patients (78.7%) were free of symptoms, while 77 (21.3%) had recurrent coronary ischemia. In conclusion, Micro-Stent II implantation without quantitative coronary angiography or intravascular ultrasound guidance and without anticoagulation was found to be effective, safe, and with good long-term outcome.

New method for placement of intracoronary stents in order to avoid their embolization in the intravascular space.

Stent dislodgment from the delivery catheter is a well-known complication of angioplasty with stent implantation. The aim of our study was to investigate the feasibility, effectiveness, and safety of a new technique of intracoronary stent implantation in order to avoid stent loss in the intravascular space. Fifty consecutive patients were candidates for angioplasty and stent placement. During angioplasty, a technique was followed according to which the guide wire "hindered" the dislodgment of the stent from the balloon catheter. Successful angioplasty and stent placement were performed in 46 out of 50 patients (92% success rate). In three cases of failure of stent implantation, the stent moved onto the balloon catheter; however, this was impeded by the guide wire. One non-Q-wave myocardial infarction occurred. No major complications (Q-wave myocardial infarction, CABG, or death) were observed. In conclusion, the technique applied was feasible enough, safe, and effective. However, the appropriate modification of its "hardware" will render it even more feasible and user-friendly.

Entrapment of angiographic catheter in the right coronary artery: a trap for the nonexperienced operator.

A case of angiographic catheter entrapment in the right coronary artery during coronary angiography in a patient with excessive tortuosity of the right iliac artery is described. Alternative manipulations in order to avoid this problem are presented.

Stent implantation in patient with visible intracoronary thrombus and compromised left ventricular function, after local thrombolysis using the Dispatch catheter.

The case of a patient with unstable angina and angiographic findings of significant (approximately 90%) right coronary artery stenosis with an intracoronary thrombus next to the lesion, total left anterior descending and circumflex occlusion and an ejection fraction of approximately 22% is described. The case was treated with stent implantation after local thrombolysis with the use of the Dispatch infusion catheter.

Successful management of right coronary air embolus after intracoronary administration of verapamil.

A case of a 50 year-old male with a coronary air embolism is described. The case was successfully treated with intracoronary administration of verapamil.

Aneurysm of the mitral-aortic intervalvular fibrosa as a rare cause of angina pectoris: angiographic demonstration.

Aneurysms of the mitral-aortic interventricular fibrosa (MAIF) are exceptionally rare complications, commonly following aortic valve endocarditis. This report describes the angiographic findings of such an aneurysm, in a patient who developed an uncommon symptomatology of unstable angina pectoris, caused by the aneurysm's expansion against the coronary arteries. Surgical treatment is also discussed.

Angioplasty followed by coronary stenting at the anastomotic site of saphenous vein bypass graft with the native vessel: a case that needs special procedural strategy.

In this report we describe a case in which a saphenous vein graft stenosis at the site of anastomosis with the left anterior descending artery (LAD) was dilated with a special Controlled Angioplasty Technology (CAT) balloon, and then stented. Balloon angioplasty and stenting at the site of anastomosis represents a technical problem because of diameter discrepancy and needs special attention in order to avoid minor or major complications.

Angioplasty without the use of "Y connector": a new, easier, bloodless method.

The "Y connector" that is used in angioplasty has the following disadvantages: 1) it is not blood-tight; 2) we need to "screw and unscrew" every time we want to inject contrast material or measure the pressure; and 3) it does not allow the advancement of the guidewire or the balloon catheter during the injection of contrast material. We created a new type of connection composed of a cut sheath for the femoral artery, connected with a cut (at the "hub") guiding catheter. The aim of this study was to examine the feasibility, efficacy, and safety of the new method. Using the new technique we performed plain-balloon angioplasty, implantation of stent, and atherectomy in 350 patients. The technical success of the method was 100%, and no complications related to the method were seen. In conclusion, the novel connection that we created eliminated all the disadvantages of the "Y connector" and was found to have 100% technical success and safety.

Contraction-excitation feedback in human atrial fibrillation.

BACKGROUND: Contraction-excitation feedback, that is, electrophysiologic changes that are caused or preceded by mechanical changes of the myocardium, has been extensively studied in the ventricles. The role of contraction-excitation feedback in the atria, and more particularly in the genesis and maintenance of atrial fibrillation, has been less adequately investigated. HYPOTHESIS: The aim of the present study was to determine whether increased right atrial pressure (RAP) facilitates the induction of atrial fibrillation (AF) in patients with a history of lone AF. METHODS: Sixteen patients with a history of paroxysmal AF but without structural heart disease were included in the study. All patients underwent electrophysiologic study at both a lower (3.1 +/- 2.0 mmHg) and (in 13 cases) a higher (6.4 +/- 2.5 mmHg) RAP. "Higher" was considered the pressure following rapid (in about 30 min) intravenous administration of normal saline or before the administration of a diuretic. RESULTS: Rapid atrial pacing induced AF in 19 of 29 attempts. At a lower pressure, rapid pacing induced brief (3 s to 3 min) AF in 3 of 16 patients, long-lasting (> 3 min) AF in 3 of 16 patients, and no AF in 10 of 16 patients. At a higher pressure, brief AF was induced in 3 of 10 patients in whom no AF could be induced at a lower pressure, and long-lasting AF in 10 patients in whom either brief AF (3 cases) or no AF (7 cases) was induced at a lower pressure. In 11 patients, in whom Wenckebach periodicity was determined at both higher and lower pressure, the critical cycle length at which atrioventricular block appeared was significantly (p < 0.001, paired t-test) longer (349.1 +/- 44.4 ms, i.e., +15.5 +/- 11.3 ms) at higher than at lower atrial pressure (333.6 +/- 41.0 ms). In nine patients, in whom Wenckebach periodicity was determined and two rhythms occurred at different pressures, the critical cycle length was 332.2 +/- 45.8 ms when associated with sinus rhythm, and significantly (p < 0.01) longer (344.4 +/- 48.0 ms, i.e., +12.2 +/- 8.3 ms) when associated with induction of AF. CONCLUSION: In patients with lone atrial fibrillation, modest increases in atrial pressure may facilitate the induction of atrial fibrillation.

Electrophysiologic abnormalities of cardiac function in progressive systemic sclerosis.

The heart has been generally recognized as a target organ in progressive systemic sclerosis. Noninvasive studies have assessed the incidence and prognostic importance of cardiac arrhythmias in these patients. However, detailed exploration of the function of impulse formation and the conduction system of the heart in these patients has never been reported. Therefore, invasive electrophysiologic studies were performed in 30 patients with systemic sclerosis, all of whom had neither obvious cardiac involvement nor cardiac arrhythmias, and in 32 subjects with no evidence of heart disease, who served as a control group. Corrected sinus node recovery time in patients with systemic sclerosis was significantly longer (P < .001) than in the control group, as was the HV interval (P < .05). Of the 30 patients with systemic sclerosis, 10 had an HV interval of 60 ms or longer. In four patients with systemic sclerosis, the recorded AH interval exceeded 125 ms. The intra-atrial conduction time tended to increase to a significant degree (P < .05) in patients with systemic sclerosis. The interatrial conduction time was much longer (P < .001), and the maximal conduction delay to the atrioventricular junction and to the distal coronary sinus was much greater in the patients with systemic sclerosis than in the control group (P < .001 for both). Supraventricular tachyarrhythmias were induced in 15 patients with systemic sclerosis versus 3 control group subjects (P < .001). With respect to corrected sinus node recovery time, AH and HV intervals, atrial vulnerability, and ventricular tachycardia, 3 of the 30 patients with systemic sclerosis had abnormal findings in one of these parameters and 14 had abnormalities in more than one. These results suggest that a broad spectrum of electrophysiologic abnormalities is present in patients with systemic sclerosis, which can be revealed only by invasive studies. Furthermore, this study provides additional support for the hypothesis that diffuse myocardial involvement is characteristic of scleroderma patients, since a number of these patients showed more than one electrophysiologic defect.

Proarrhythmic effects of reactive hypoglycemia.

A patient with refractory atrioventricular nodal reentry tachycardia is reported in whom it was possible to document that reactive hypoglycemia was the trigger for aggravation of arrhythmia. Over a period of 6 years, a series of electrophysiological studies revealed that, when the patient was in a hypoglycemic state, initiation of tachycardia was easy and most importantly that tachycardla termination by extra-stimulus pacing always failed. Furthermore, atrial fibrillation was inducible or spontaneously occurred only when the blood glucose level was reduced by IV insulin administration.

Chronic atrial fibrillation and incessant ventricular tachycardia treated with a single transcatheter ablation.

We present a unique patient with a 12-year history of chronic atrial fibrillation resistant to external direct current shocks associated with incessant ventricular tachycardia. Both arrhythmias were treated with a single shock delivered through a catheter at the atrioventricular junction. The other unusual feature is that sinus rhythm has been maintained in a follow-up of 6 months after the intervention.

Pressure-related ventricular tachycardia.

A case with syncope on exertion and paced heart block is presented. Non-sustained ventricular tachycardia was seen on Holter monitoring and reproduced repeatedly by either exercise or an injection of an alpha agonist, but not with provocative electrophysiology. Antihypertensive treatment using a beta-blocker with endogenous sympathomimetic activity prevented recurrences. It is suggested that this is a case of pressure-related tachycardia.

Electrophysiologic studies of the heart in patients with rheumatoid arthritis.

We investigated the electrophysiological properties of the heart in patients with definite or classical rheumatoid arthritis using programmed electrical stimulation techniques. Twelve patients with rheumatoid arthritis and without evidence of organic heart disease or arrhythmia detectable with serial electrocardiograms and 24-hour ambulatory electrocardiographic monitoring were compared with 12 control subjects. Stimulation was performed from the high right atrium and right ventricular apex at a drive cycle length of 600 msec and the recording sites included high right atrium, atrioventricular junction and distal coronary sinus. There was no statistically significant difference in the corrected sinus node recovery time between the study and control group of patients. Similarly, no differences from normal were found in the AH and HV intervals or in the atrial and ventricular refractoriness, whereas the atrioventricular nodal effective refractory period was higher in patients with rheumatoid arthritis, compared with the control group (338 +/- 38 vs 286 +/- 29, P less than 0.02). The atrial conduction time during basic cycle length had a tendency to increase from high right atrium to atrioventricular junction in the study group and reached statistical significance from high right atrium to coronary sinus (92 +/- 15 vs 74 +/- 14, P less than 0.05). Electrophysiologic differences between the study and control patients also included a greater increase in maximal intraatrial (40 +/- 13 vs 27 +/- 16, P less than 0.05) and interatrial conduction delay (54 +/- 16 vs 31 +/- 12, P less than 0.01) of early premature stimuli in patients with rheumatoid arthritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Valvuloplasty with large trefoil balloons for the treatment of congenital pulmonary stenosis.

Percutaneous balloon valvuloplasty was performed in 16 children, 1 1/2 to 14 years old, with congenital pulmonary stenosis with teh use or trefoil balloons. These balloons, which consist of 3 identical angioplasty balloons, do not interrupt completely the blood flow during inflation. The size of the trefoil balloons used was 30 to 50% larger than the valve anulus. A obtain an effective pulmonary valvuloplasty in two patients with large valve anulus. The mean prevalvuloplasty systolic gradient fo 78.2 +/- 28.9 mmHg (range 40 to 140 mmHg) was reduced to 20.3 +/- 5.7 (range 10 to 30 mmHg) after valvuloplasty. No patient developed significant hypotension or bradycardia or other complications as a result of the procedure. The findings demonstrate that percutaneous balloon valvuloplasty with oversized trefoil balloons effectively treated congenital pulmonary stenosis without complications in the cases studied. The use of large trefoil instead of single balloons of a similar diameter is advantageous since they cause no significant compromise of the cardiac output during valvuloplasty.

Cardiac involvement in postnatal rubella.

Two cases of rubella myocarditis are reported: a 6-year-old boy who developed a complete, distal to His, atrioventricular block, during the third day of illness; and a 12-year-old boy who developed myocarditis with congestive heart failure 20 days following rubella infection. Although permanent pacing was required in the first patient, six years later he showed a normal growth and maintained normal activity. The second patient has deteriorated markedly and 6 months after the initial illness he had severe heart failure. It should be noted that myocarditis with abnormalities of the conduction system or congestive heart failure may be a complication to postnatal rubella.