Long-term effects of spinal cord stimulation on myocardial ischemia and heart rate variability: results of a 48-hour ambulatory electrocardiographic monitoring.

BACKGROUND: Spinal cord stimulation (SCS) has analgesic properties and may be used to treat pain in patients with therapeutically refractory angina who are unsuitable for myocardial revascularization. Some studies have also demonstrated an anti-ischemic effect. The aim of this study was to evaluate the long-term persistence of the effects of SCS on myocardial ischemia and on heart rate variability. METHODS: Fifteen patients (9 males, 6 females, mean age 76 +/- 8 years, range 58-90 years) with severe refractory angina pectoris (Canadian class III-IV), on optimal pharmacological therapy, unsuitable for myocardial revascularization and treated with SCS for a mean follow-up of 39 +/- 27 months (range 9-92 months) were studied. Eleven patients had had a previous myocardial infarction and 5 a coronary artery bypass graft. The mean ejection fraction was 54 +/- 7% (range 36-65%). All patients underwent 48-hour ambulatory ECG monitoring and were randomly assigned to 24 hours without SCS (off period) and 24 hours with SCS (on period). The primary endpoints were: number of ischemic episodes, total duration of ischemic episodes (min), and total ischemic burden (mV*min). RESULTS: The heart rate was not statistically different during the off and on SCS periods (median 64 and 67 b/min respectively). The number of ischemic episodes decreased from a median of 6 (range 0-29) during the off period to 3 (range 0-24) during the on period (p < 0.05). The total duration of ischemic episodes decreased from a median of 29 min (range 0- 186 min) during the off period to 16 min (range 0-123 min) during the on period (p < 0.05). The total ischemic burden decreased from a median of 2.5 mV*min (range 0-19.5 mV*min) during the off period to 0.8 mV*min (range 0-13 mV*min) during the on period (p = NS). The heart rate variability parameters were similar during the on and off periods. CONCLUSIONS: SCS exerts long-term anti-ischemic effects.

[Epidural spinal stimulation in the treatment of refractory angina pectoris. Its clinical efficacy, complications and long-term mortality. An Italian multicenter retrospective study]. / La stimolazione spinale epidurale nel trattamento dell'angina pectoris refrattaria. Efficacia clinica, complicanze e mortalità a lungo termine. Studio retrospettivo multicentrico Italiano.

BACKGROUND: Spinal cord stimulation has been used for many years in the treatment of refractory angina pectoris. Its anti-anginal and anti-ischemic effect has been well documented in several studies, but the long-term efficacy, safety and survival rate are not well known. The aim of this study was to carry out a retrospective analysis of a series of patients from the Italian Multicenter Registry, the data of which were collected in five centers, by means of a questionnaire. METHODS: One hundred and thirty patients (83 males, 47 females, mean age 74.8 +/- 9.8 years) were submitted to spinal cord stimulator implantation for refractory angina pectoris in the period 1988-1995 and controlled during a mean follow-up of 31.4 +/- 25.9 months. A previous myocardial infarction had already occurred in 69.3% of patients, whereas in 67.6% multivessel coronary artery disease was documented. A left ventricular dysfunction (ejection fraction < 0.40) was present in 34% of patients; bypass surgery and coronary angioplasty were performed in 49.6% and in 27% of patients respectively. In 96.3% of cases revascularization procedures were not advisable. RESULTS: A complete follow-up of 116 patients (89.2%) was available. The spinal cord stimulator induced a significant reduction in NYHA functional class from 2.5 +/- 1.2 to 1.5 +/- 0.9 (p < 0.01). During the follow-up 41 patients (35.3%) died, and in 14.2% a new acute myocardial infarction developed. The total percentage of minor spinal cord stimulation-related complications was 6.8%. No major complications occurred. The annual total mortality rate was 6.5%, whereas the cardiac mortality rate was 5%. Compared to the survivors, patients who died showed a higher incidence of left ventricular dysfunction, previous myocardial infarction and bypass surgery at implantation. CONCLUSIONS: In our experience, spinal cord stimulation is an effective therapy in patients affected by refractory angina pectoris and who cannot undergo revascularization procedure. The complication rate is low, with the total and cardiac mortality showing a trend as that reported for patients with similar coronary disease.

Dual chamber pacing with optimal AV delay in congestive heart failure: a randomized study.

AIM: A prospective randomized trial was set up to evaluate contractile parameters and quality of life in patients with congestive heart failure. METHODS AND RESULTS: We describe the results from 38 patients in sinus rhythm and with chronic heart failure due to congestive cardiomyopathy, prospectively randomized to optimal medical therapy (Group 1, 19 patients) or optimal medical therapy plus dual chamber pacemaker programmed to optimal AV delay (Group 2, 19 patients). At a 6 month follow-up, 7/19 patients in Group 1 had died compared with 5/19 patients in Group 2. During follow-up, there were few significant changes in evaluated parameters except for mitral regurgitation time, which was prolonged in Group 1 and shortened in Group 2. The systolic left ventricular diameter shortened significantly only in Group 2. An energy and activity questionnaire showed that the effect of DDD pacing in the latter patient population was beneficial. CONCLUSIONS: From these results we may conclude that at the 6 month follow-up DDD pacing with echo-optimized AV interval programming can improve quality of life without affecting survival.

Multicenter clinical evaluation of a new SSIR pacemaker.

A multicenter clinical evaluation of Sorin Swing 100, a new SSIR pacemaker with a gravimetric sensor, was performed by seven different centers enrolling a total of 89 patients, 56 men and 33 women, mean age 73.1 years, for pacemaker implantation (73 patients) or pacemaker replacement (16 patients). Pacing mode was VVIR in 73 patients and AAIR in 16. The behavior of pacing rate was evaluated 3 months after the implant by performing a 24-hour Holter monitor, an exercise stress test, and tests for the assessment of mechanical external interference (MEI). A physiological behavior of the paced rate was always observed during Holter monitoring. In 52 completely paced patients mean diurnal, nocturnal, and maximal heart rate were, respectively, 74.9 +/- 5.7 ppm, 58.1 +/- 5.8 ppm, and 113.4 +/- 12.7 ppm; a paced rate exceeding 100 ppm was reached on the average 5.6 times/Holter monitor. In all but two patients the sleep rate (55 ppm) was reached during the night or long resting time. During exercise stress test a direct correlation between the increase in pacing rate and the increase in workload was observed; the mean maximal heart rate reached in 49 completely paced patients was, respectively, 102.8 +/- 9 ppm in 17 patients who accomplished stage 1, 116.2 +/- 13.6 ppm in 28 patients who accomplished stage 2, and 133 +/- 6.7 ppm in 10 patients who accomplished stage 3 of the Bruce protocol. MEI testing never increased the pacing rate over the noise rate (10 ppm over the basic rate). In only seven patients the results obtained suggested to change the nominal set up of the pacemaker.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful catheter ablation by radiofrequency energy of posteroseptal accessory pathway in a patient with drug refractory Wolff-Parkinson-White syndrome.

A 45-year-old patient with the Wolff-Parkinson-White syndrome suffering from recurrent intractable reciprocating atrioventricular tachycardia (RAVT) is reported. He used amiodarone, sotalol, quinidine, propafenone and flecainide unsuccessfully. An electrophysiological study (EPS) performed with four catheters localized the site of the anomalous pathway in the ostium of the coronary sinus. In this region we could also record a Kent potential. In the ostium of the coronary sinus, radiofrequency energy was repeatedly applied until the conduction over the accessory pathway was abolished both in the anterograde and the retrograde direction. The Kent deflection detectable before ablation, could not be detected after it. During follow-up (1 month) the patient remained asymptomatic and the control EPS showed no evidence of pre-excitation, either anterogradely or retrogradely.

[Post-ischemic inversion of the T wave]. / L'inversione post-ischemica dell'onda T.

The significance of new T wave inversion (so called post-ischemic T wave inversion) in the basal electrocardiogram of patients suffering from unstable angina is still controversial. Some AA suggest that the patients who develop this ecg pattern represent a subgroup with poor prognosis, particularly when to deep negative T waves (greater than 3 mm) a long QT interval is associated (giant negative T waves). On the contrary other AA suggest that there is not a different prognosis between patients which develop and which do not develop post-ischemic T waves (post-I T waves). We studied 113 patients with unstable angina: 95 patients were reviewed retrospectively (group I), 18 patients were studied perspectively (group II). In group I 63/95 developed post-I T waves (49 in anterior, 9 in inferior and 5 in both anterior and inferior leads) while 32/95 did not develop post-ischemic T waves. In group II all 18 patients developed post-ischemic T waves according to the characteristics of giant negative T waves. Follow up periods were 62 +/- 36 months in group I and 11 +/- 7 months in group II. In 61 cases (45 of group I and 16 of group II) the electrocardiogram was registered during anginal pain. ST increase and/or pseudonormalization of T wave from negative to positive, indicating transmural ischemia, was observed in 59% of patients with post-ischemic T waves vs 30% of pts without post-ischemic T waves (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of oral calcium-antagonists in spontaneous angina. Verapamil and nifedipine in a double-blind cross-over trial.

Verapamil and nifedipine, two calcium-antagonist drugs, were evaluated in a double-blind cross-over trial. The study was performed in 15 patients admitted to our Coronary Care Unit for spontaneous angina. Before and after a 24 hours placebo period, oral verapamil 480 mg daily and oral nifedipine 60 mg daily were administered alternatively. Symptomatic as well as asymptomatic ischemic episodes with ST segment elevation or depression and ventricular and supraventricular ectopic beats were documented by continuous electrocardiographic Holter monitoring. The average number of attacks during the placebo periods was 243; the number of attacks decreased to 129 during verapamil treatment (P less than 0.05) and to 57 during nifedipine treatment (P less than 0.01). Ventricular ectopic beats decreased with both drugs while supraventricular ectopic beats decreased only during verapamil treatment. The difference was not statistically significant because of a small number of observations. In conclusion the two drugs appear to be effective in the management of patients with unstable angina at rest, especially in the variant form.

The anterior displacement of the QRS loop as a right ventricular conduction disturbance. Electrophysiologic and vectorcardiographic study in man.

Anterior displacement (AD) of the QRS horizontal loop (Frank VCG method) was induced by programmed right atrial stimulation (PRAS) in 15 cases. When AD occurred we noticed changes of the terminal QRS vectors and of the T loop similar to those observed in incomplete right bundle branch block (RBBB). The increasingly anticipated extrastimuli induced progressively the AD and then progressive degrees of RBBB. The anterior shifting of the efferent limb never appeared after the induction of RBBB. A left conduction disturbance never appeared after the AD. In cases of supposed incomplete left bundle branch block (i.e. left ventricular hypertrophy) the QRS duration decreased when the AD was induced. Therefore, the AD induced by PRAS and probably those observed in some clinical cases are due to a right ventricular conduction disturbance.