L. Molina

Medium-Term Effects of Septal and Apical Pacing in Pacemaker-Dependent Patients: A Double-Blind Prospective Randomized Study

Pacing the right ventricle is established practice, but there remains controversy as to the optimal site to preserve hemodynamic function.

3. Vasovagal Syncope, Tilt Testing

Objective To evaluate the sensitivity and specificity and to establish the positive and negative predictive values for the tilt test in patients with syncope of unknown origin. Methods We studied patients with history of dizziness or syncope without any underlying cardiac condition (group A), and another group consisting of healthy volunteers that did not have history of dizziness or syncope (group B). They were initially tilted upright to 70° during 30 min. If the result was negative, 5 mg of sublingual isosorbide dinitrate were given and the patients were tilted upright to 70° again. Results Of the last 156, a total of 134 patients (45 males and 89 females, mean age of 27.9±14 yrs) had had syncope (Group A), whereas 22 were normal subjects (7 male and 15 females, mean age of 25.4±6.4) that volunteered for the same test. During the panic phase of tilt test syncope occurred in 25 patients (18.7%) of group A, and 5 (22.7%) of group B. 109 were submitted to the drug phase: (81.3%) of group A, and 17 (72.3%) of group B. Sixty patients of group A (55%), and 8 of group B (47%) had a positive test. This increased sensitivity from 18 to 55% and decreased specificity from 77 to 52%. The positive rate of tilt test was 62.8%, the sensitivity 63% and the specificity 40%; the positive predictive value was 0.86, and the negative predictive value 0.15. Conclusions We consider that either the tilt test is not the ideal to evaluate vaso-vagal syncope, or this is only a physiological condition related to other factors such as anxiety.

3. Vasovagal Syncope, Tilt Testing3.4 Validation of the Head-Up Tilt Test in Patients with Syncope

Objective To evaluate the sensitivity and specificity and to establish the positive and negative predictive values for the tilt test in patients with syncope of unknown origin. Methods We studied patients with history of dizziness or syncope without any underlying cardiac condition (group A), and another group consisting of healthy volunteers that did not have history of dizziness or syncope (group B). They were initially tilted upright to 70° during 30 min. If the result was negative, 5 mg of sublingual isosorbide dinitrate were given and the patients were tilted upright to 70° again. Results Of the last 156, a total of 134 patients (45 males and 89 females, mean age of 27.9±14 yrs) had had syncope (Group A), whereas 22 were normal subjects (7 male and 15 females, mean age of 25.4±6.4) that volunteered for the same test. During the panic phase of tilt test syncope occurred in 25 patients (18.7%) of group A, and 5 (22.7%) of group B. 109 were submitted to the drug phase: (81.3%) of group A, and 17 (72.3%) of group B. Sixty patients of group A (55%), and 8 of group B (47%) had a positive test. This increased sensitivity from 18 to 55% and decreased specificity from 77 to 52%. The positive rate of tilt test was 62.8%, the sensitivity 63% and the specificity 40%; the positive predictive value was 0.86, and the negative predictive value 0.15. Conclusions We consider that either the tilt test is not the ideal to evaluate vaso-vagal syncope, or this is only a physiological condition related to other factors such as anxiety.

Validation of the Head-Up Tilt Test in Patients with Syncope

Objective To evaluate the sensitivity and specificity and to establish the positive and negative predictive values for the tilt test in patients with syncope of unknown origin. Methods We studied patients with history of dizziness or syncope without any underlying cardiac condition (group A), and another group consisting of healthy volunteers that did not have history of dizziness or syncope (group B). They were initially tilted upright to 70° during 30 min. If the result was negative, 5 mg of sublingual isosorbide dinitrate were given and the patients were tilted upright to 70° again. Results Of the last 156, a total of 134 patients (45 males and 89 females, mean age of 27.9±14 yrs) had had syncope (Group A), whereas 22 were normal subjects (7 male and 15 females, mean age of 25.4±6.4) that volunteered for the same test. During the panic phase of tilt test syncope occurred in 25 patients (18.7%) of group A, and 5 (22.7%) of group B. 109 were submitted to the drug phase: (81.3%) of group A, and 17 (72.3%) of group B. Sixty patients of group A (55%), and 8 of group B (47%) had a positive test. This increased sensitivity from 18 to 55% and decreased specificity from 77 to 52%. The positive rate of tilt test was 62.8%, the sensitivity 63% and the specificity 40%; the positive predictive value was 0.86, and the negative predictive value 0.15. Conclusions We consider that either the tilt test is not the ideal to evaluate vaso-vagal syncope, or this is only a physiological condition related to other factors such as anxiety.

6. AVNRT: Electrophysiological Aspects and Ablation Results6.1 Nodal Conduction Velocity According to Site of Stimulus Origin

Objective Establish if the nodal conduction velocity is different if the impulse comes from the left atrium in relation to the right. Methods Twenty patients submitted to an electrophysiological study for different reasons were paced during sinus rhythm with an S1 series followed by six test stimuli emulating the beginning of a supraventricular tachycardia. Identical stimuli sets were given in the coronary sinus and the high right atrium. We then considered the Sx-Hx interval. Results The mean Sx-Hx interval stimulating the right atrium was 220 ±37, vs. 170 ±35 ms (p<0.0003) when the stimulus was in the coronary sinus, which represents a 29% difference. Effective (222 ±49 vs. 230 ±40 ms.) and functional (314 ±53 vs. 320±54 ms.) refractory periods were similar from both atria. Comparing conduction curves to find refractory periods, the S2-H2 interval pacing in the coronary sinus was 27.4% shorter than that from the high right atrium. Comparing anatomical distances in an anatomical piece, both distances were similar (65 ±5 mm). Conclusions Nodal conduction is significantly faster (30%) if the impulse comes from the left atrium compared to the right.

Nodal Conduction Velocity According to Site of Stimulus Origin

Objective Establish if the nodal conduction velocity is different if the impulse comes from the left atrium in relation to the right. Methods Twenty patients submitted to an electrophysiological study for different reasons were paced during sinus rhythm with an S1 series followed by six test stimuli emulating the beginning of a supraventricular tachycardia. Identical stimuli sets were given in the coronary sinus and the high right atrium. We then considered the Sx-Hx interval. Results The mean Sx-Hx interval stimulating the right atrium was 220 ±37, vs. 170 ±35 ms (p<0.0003) when the stimulus was in the coronary sinus, which represents a 29% difference. Effective (222 ±49 vs. 230 ±40 ms.) and functional (314 ±53 vs. 320±54 ms.) refractory periods were similar from both atria. Comparing conduction curves to find refractory periods, the S2-H2 interval pacing in the coronary sinus was 27.4% shorter than that from the high right atrium. Comparing anatomical distances in an anatomical piece, both distances were similar (65 ±5 mm). Conclusions Nodal conduction is significantly faster (30%) if the impulse comes from the left atrium compared to the right.

6. AVNRT: Electrophysiological Aspects and Ablation Results

Objective Establish if the nodal conduction velocity is different if the impulse comes from the left atrium in relation to the right. Methods Twenty patients submitted to an electrophysiological study for different reasons were paced during sinus rhythm with an S1 series followed by six test stimuli emulating the beginning of a supraventricular tachycardia. Identical stimuli sets were given in the coronary sinus and the high right atrium. We then considered the Sx-Hx interval. Results The mean Sx-Hx interval stimulating the right atrium was 220 ±37, vs. 170 ±35 ms (p<0.0003) when the stimulus was in the coronary sinus, which represents a 29% difference. Effective (222 ±49 vs. 230 ±40 ms.) and functional (314 ±53 vs. 320±54 ms.) refractory periods were similar from both atria. Comparing conduction curves to find refractory periods, the S2-H2 interval pacing in the coronary sinus was 27.4% shorter than that from the high right atrium. Comparing anatomical distances in an anatomical piece, both distances were similar (65 ±5 mm). Conclusions Nodal conduction is significantly faster (30%) if the impulse comes from the left atrium compared to the right.