Radiofrequency catheter ablation of posteroseptal accessory pathways--results of a step-by-step ablation approach.

INTRODUCTION: Transcatheter radiofrequency ablation of posteroseptal accessory pathways (AP) is challenging. A number of different interventional approaches have been suggested by different groups. The selection of the initial approach is crucial in order to reduce radiation exposure and the number of unsuccessful lesions applied. We present our ablation technique as guided by a simplified electrocardiographic analysis of the delta wave polarity and the electrophysiologic mapping results. METHODS AND RESULTS: Out of 35 manifest APs encountered in the right (n=17) or the left posteroseptum (n=18) in 35 patients, 34 were successfully ablated. Despite their left sided location, 7 of the 18 "left" sided APs were ablated after switching from an initial arterial to a venous approach looking for an appropriate target site in the right posteroseptal space or within the coronary sinus network. The other 11 left sided APs were ablated in the mitral ring, on 2 occasions, on their atrial aspect through a retrograde transmitral approach. On the contrary, 16 of the 17 "right" sided APs were successfully ablated exclusively through a venous approach. Fourteen of these were ablated in the right posteroseptum, in 2 cases, only after reaching their ventricular aspect. Two right sided APs were interrupted in the coronary sinus os and the middle cardiac vein respectively. CONCLUSION: It appears that even though the electrocardiographic and electrophysiologic location of the AP in the posteroseptal space helps select the appropriate initial approach, it does not always guarantee a successful ablation procedure in the expected site of the corresponding atrioventricular ring. Not uncommonly, it will be necessary to look after intermediate target sites within the coronary sinus to improve the overall ablation success rate.

Ischemia-induced reflex sympathoexcitation during the recovery period after maximal treadmill exercise testing.

BACKGROUND: Heart rate variability (HRV) analysis is problematic during maximal treadmill exercise testing (ET) due to rapidly changing heart rate. HYPOTHESIS: The aim of this study was to assess HRV spectral components during treadmill ET in patients with coronary artery disease (CAD) and in healthy controls, and to search for possible differences between the two groups. METHODS: Thirty patients with CAD and 30 age-matched healthy controls underwent symptom-limited ET and continuous electrocardiographic monitoring. For adequate assessment of HRV during maximal ET, we calculated the HRV measures [normalized units (NU)]--low-frequency (0.040-0.150 Hz) power (LF), high-frequency (0.150-0.400 Hz) power (HF), and the LF/HF ratio--from all the sequential stages of the ET with limited changes (20 beats/min) in heart rate (stress 80-100, 100-120, 120-140, 140-160, 160-180/recovery 180-160, 160-140, 140-120, 120-100, 100-80). RESULTS: Both LF and HF were found to decrease gradually during ET and to increase during the recovery period in both patients and controls (p < 0.001). LF values were higher during the recovery period than during the respective stages of exercise time in both patients and controls, and LF/HF ratio was higher during recovery in patients only. CONCLUSIONS: During maximal ET (1) vagal tone withdraws during the exercise time and increases during the recovery period; (2) the sympathetic activity predominates during the recovery period, especially in patients with CAD and exercise-induced myocardial ischemia. This finding raises the possibility of ischemia-induced cardiocardiac sympathetic excitatory reflexes.

Assessment of time domain and spectral components of heart rate variability immediately before ischemic ST segment depression episodes.

In an attempt to study autonomic function during the 5-minute period preceding ischemic ST segment depression (decreases ST) episodes, we selected 138 decreases ST episodes, without preceding decreases ST during the last 15 minutes before each episode, from the Holter tapes of 35 patients with multivessel coronary artery disease. For the 5-minute period preceding each decreases ST episode, we calculated the following heart rate variability (HRV) indices; the mean RR interval (RR5), the standard deviation of all RR intervals (SD Index5), the corresponding coefficient of variation (CV5), and the natural log (Ln) of the spectral components, total power at 0.000 to 0.400 Hz (TP5), low frequency power at 0.040 to 0.150 Hz (LF5), high frequency power at 0.150 to 0.400 Hz (HF5), and the ratio of the low to high frequency power (LF5/HF5). As HRV indices of the 24-hour period, we calculated the respective RR, SD Index, CV, LnTP, LnLF, LnHF, and Ln LF/HF. RR5, SD Index5, CV5, and Ln TP5 were all significantly lower than RR (t = -5.343, p = 3.7 x 10(-7)), SD Index (t = -19.091, p = 1.99 x 10(-40)), CV (t = -15.780, p = 1.28 x 10(-32)), and LnTP (t = -3.210, p = 0.0016), respectively. LnHF5 was inversely correlated with the magnitude of the decreases ST; r = -0.174, P < 0.05, and CV5 was inversely correlated with the natural log (Ln) of the ischemic event duration; r = -0.183, P < 0.05. Analogous results were obtained for both the painful and silent decreases ST episodes. It is concluded that HRV is decreased during the 5-minute period preceding decreases ST episodes, and is inversely related with the magnitude and the duration of the *ST.

Significance of arterial hypertension on coronary collateral circulation development and left ventricular function in coronary artery disease.

To assess the role of arterial hypertension in the development of coronary collateral circulation in relation to coronary artery disease, severity and left ventricular function, we studied 433 men with angiographically documented coronary artery disease. Of these, 122 showed disease in one vessel, 157 showed disease in two vessels and 159 patients showed disease in three vessels; 153 (35.3%) patients had arterial hypertension. The hypertensive patients had a similar distribution of diseased coronary vessels and similar coronary obstruction scores according to Gensini compared with the normotensive patients (64 versus 62, NS), but they had higher left ventricular ejection fraction values (51.5 versus 46.8%, P = 0.002). Coronary collateral circulation was more often seen in hypertensives (70.6 versus 57.1%, P = 0.006), especially high-grade coronary collateral circulation (27 versus 15%, P = 0.001). However, patients with coronary collateral circulation had more severe coronary artery disease, whether they had arterial hypertension (71 versus 46, P = 0.00008) or not (76 versus 43, P less than 0.00001). Thus, for a similar severity of coronary artery disease, patients with arterial hypertension and also coronary collateral circulation had higher ejection fraction values (52.6 versus 46.1%, P = 0.0006). This was more readily observed in those patients with disease in three vessels and coronary collateral circulation (52 versus 42.8%, P = 0.002). Patients without coronary collateral circulation had similar ejection fraction and coronary obstruction score values, irrespective of arterial hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)