Sensing Through the Esophagus for Temporary Atrial Synchronous Ventricular VDD Pacing

The purpose of this study was to evaluate the effectiveness and safety of temporary VDD pacing using an esophageal electrode for sensing of the atrial electrogram. We studied 15 patients, 8 men and 7 women, aged 77 ± 2 years (mean ± SE, range 61–90), with severe atriovenfricular (AV) conduction disturbances. A 24-hour beat-to-beat ECG analysis was used to evaluate the effectiveness of the pacing system and special tests were performed to test the stability of pacing and sensing. The system performed satisfactorily in 12 of the 15 patients. The 24-hour Holter ECG monitoring revealed the following percentages of beats: 96.32 ± 0.5 VDD, 2.92 ± 0.6 VVI, and 0.14 ± 0.05 paced beats resulting from pseudosensing. All the latter were single, with no bigeminy or salvos. The results of the stability tests were as follows: the percentage of VDD beats was significantly lower than the 24-hour mean when the patient lay on his right side (92.8 ± 0.5, P < 0.001), during the swallowing of liquids (91.26 ± 0.4, P < 0.001) and soft foods (84.2 ± 1.4, P < 0.001), and during coughing (94.2 ± 0.6, P < 0.001). The percentage of VVI type beats increased in these four cases (6.7 ± 0,5, 7.2 ± 0.3, 13.2 ± 1.2 and 4.8 ± 0.4, respectively, P < 0.001 in each case). The percentage of ectopic beats due to pseudosensing did not change significantly during any of the tests. These results indicate that the method described is a safe and effective technique for temporary VDD pacing.     

Insertable Loop Recorder in Unmasking the Cause of Syncope

SIMANTIRAKIS, E.N., et al. : Insertable Loop Recorder in Unmasking the Cause of Syncope. During the last few years closed loop recorders are being used increasingly in the investigation of unexplained syncope. Our patient had a 5-year history of pre- and syncopal episodes in which the usual invasive and noninvasive tests were nondiagnostic. Finally, a loop recorder was implanted that revealed the cause of the syncope a few days after implantation: a fast, sustained, ventricular tachycardia originating from the right ventricular outflow tract. Loop recorders will undoubtedly contribute toward the decrease in the percentage of undiagnosed syncope cases and possibly to the reduction of the investigation cost.     

The Effect of DDD Pacing on Ergospirometric Parameters and Neurohormonal Activity in Patients with Hypertrophic Obstructive Cardiomyopathy

This study examined the acute and long-term effects of DDD pacing on ergospirometric parameters and neurohormonal activity in patients with hypertrophic obstructive Cardiomyopathy (HOCM). We studied eight patients (five males), aged 56 ± 7 years, with HOCM refractory to drugs. In all patients a DDD pacemaker was implanted and programmed with an atrioventricular (AV) delay that insured full ventricular activation. The patients underwent echocardiographic examination and exercise stress testing before and 3 days, 3 months, and 12 months after pacemaker implantation. Oxygen consumption was measured at the anaerobic threshold (VO_2AT) and peak exercise (pVO₂). Atrial natriuretic peptide (ANP) and cyclic adenosine monophosphate (c-AMP) levels were measured concomitantly. Left ventricular outflow tract (LVOT) pressure gradient decreased significantly from 70 ± 18 to 25 ± 12 mmHg (P < 0.05) 3 days after pacing and remained unchanged at 3 and 12 months. pVO₂ and VO_2AT increased significantly, from 20.1 ± 3 to 23.4 ± 3 mL/kg/min and from 16 ± 3 to 17.8 ± 2 mL/kg/min, respectively (P < 0.05). This improvement continued up to 3 months, and then remained stable until the end of the 12-month follow-up period. ANP levels decreased at 3 days from 85.4 ± 5.7 to 75.4 ± 7.3 fmol/mL (P < 0.05), and remained unchanged over the 12 months. c-AMP levels did not change significantly after the onset of pacing. DDD pacing in patients with HOCM not only reduces the LVOT pressure gradient but also causes a significant early and long-term improvement in exercise capacity and neurohormonal profile.     

Lectin histochemistry of laryngeal squamous cell carcinomas

A panel of five biotinylated lectins was applied to study the presence and distribution of membrane carbohydrate residues in the normal laryngeal epithelium and in laryngeal squamous cell carcinomas (SCCs) of 86 patients with the avidin-biotin peroxidase complex technique. The lectin-binding pattern of well-differentiated SCCs was comparable to that of the spinous cells of the normal laryngeal epithelium. In the less differentiated SCCs, staining of the keratinocyte plasma membrane with lectins was either reduced or absent, indicating a decline in the glycosylation of cell surface glycoconjugates. The lectins applied here could be used in the rapid assessment of less-differentiated areas within a laryngeal SCC, but they cannot be regarded as reliable markers of laryngeal keratinocytes undergoing malignant transformation. (Otolaryngol Head Neck Surg 1998;118:886-91.)