Low power radiofrequency electromagnetic radiation for the treatment of pain due to osteoarthritis of the knee.

OBJECTIVE: To investigate the analgesic effect of low power radiofrequency electromagnetic radiation (RF) in osteoarthritis (OA) of the knee. METHODS: In a randomized study on 40 patients the analgesic effect of RF was compared with the effect of transcutaneous electrical nerve stimulation (TENS). RF and TENS applications were repeated every day for a period of 5 days. The therapeutic effect was evaluated by a visual analogue scale (VAS) and by Lequesne's index: tests were performed before, immediately after and 30 days after therapy. RESULTS: RF therapy induced a statistically significant and long lasting decrease of VAS and of Lequesne's index; TENS induced a decrease of VAS and of Lequesne's index which was not statistically significant. CONCLUSIONS: A therapeutic effect of RF was therefore demonstrated on pain and disability due to knee OA. This effect was better than the effect of TENS, which is a largely used analgesic technique. Such a difference of the therapeutic effect may be due to the fact that TENS acts only on superficial tissues and nerve terminals, while RF acts increasing superficial and deep tissue temperature.

[Monitoring of ischemic changes of the QRS complex with a new system of computerized electrocardiography]. / Monitoraggio delle alterazioni ischemiche del complesso QRS mediante un nuovo sistema di elettrocardiografia computerizzata.

BACKGROUND: Evoked ischemia induces morphological modifications in QRS complex that can be detected by a new electrocardiographic computerized system that we have developed (ventricular ischemic site analysis-VISA). The aim of this study was to evaluate, by continuous recording, the ischemia evolution during stress or pharmacological test and to correlate the modifications of QRS with the shift of the ST-T segment. METHODS: According to our method, the vectorial differences between rest QRS and stress QRS are recorded as deformations of the QR and/or RS segments. Sixty patients were studied: 44 had inducible ischemia during single photon emission computed tomography 99mTc-sestamibi test; 33 of these underwent ergometric test and 11 pharmacological test. RESULTS: The VISA test was positive in 91% of patients against the 61% with standard ECG. Ischemic deformations of the QRS appeared at 62.1% of stress duration, while the ST-T shift appeared at 81.4% of the test. During pharmacological stress the ST-T segment did not change. CONCLUSIONS: Our method is more sensitive than standard ECG in identifying inducible ischemia. Ischemic deformations of the QRS complex occur earlier than the repolarization modifications and they may be present also in their absence. The higher sensitivity of the VISA test depends on the fact that QRS ischemic modifications are caused both by the lesion current and a conduction delay in the ischemic zone.

[A new computerized electrocardiographic method of the study of the QRS complex in the diagnosis of myocardial ischemia (preliminary results)]. / Nuovo metodo elettrocardiografico computerizzato per lo studio del complesso QRS nella diagnosi di ischemia miocardica (risultati preliminari).

Based on the premise that the QRS complex is also involved in reversible ischemia, we designed a computerized electrocardiographic method, that we have named Ventricular Ischemic Site Analysis (VISA). This method compares mean resting QRS to the QRS complex recorded during exercise or pharmacologic stress. The effect of ischemia on the electrical process of myocardial depolarization can be seen as a smaller slope in the QR and/or RS segment of the QRS signal, thus causing a local change in shape of the QRS. This method makes it possible to evaluate both the maximum entity of the change in shape and the time at which this occurs with reference to the beginning of the cycle. The VISA test was compared to SPECT and to the normal ECG stress test on a group of 53 patients who underwent a SPECT 99mTc-Sestamibi for suspected myocardial ischemia. Among the 39 patients confirmed as ischemic, the VISA test was positive in 37, while the ischemic alterations of the ST-T segment were observed in only 10 patients. According to this study, the sensitivity of the VISA test is comparable to the levels seen in SPECT. Moreover, this method demonstrates a trend towards localization of the ischemia in posterior or lateral sites when the shape change in localized in RS segment, and in anterior or infero-apical sites when the change is in QR segment. In addition to increasing sensitivity with respect to normal ECG stress tests, this method may also represent a new field of application for the ECG stress test, offering the possibility of localizing ischemic areas via simple computerized electrocardiography.

Implantable pharmacological defibrillator (AIPhD): preliminary investigations in animals.

The treatment of ventricular fibrillation (VF) by means of automatic implantable cardioverter defibrillators (AICD) poses many severe problems and limitations at the present time. In order to overcome these problems, we propose a totally new way to terminate VF or ventricular sustained tachycardia (VST). Our proposal consists of replacing the electric shock, which is dangerous, delayed, and sometimes ineffective, with a "chemical" shock: i.e., a chemical bolus retroperfused in the coronary sinus (CS) immediately after VF arises. The possible device is hypothesized and preliminary investigations in animals, performed to verify the theoretical assumption, are presented. In rabbits, and in larger animals (sheep and swine). Drugs were perfused in the coronary bed: lidocaine was used in 86% and bretylium tosylate in 14% of the animals. The results were: lidocaine immediately terminated VF in 100% and sinus rhythm was restored in rabbits; lidocaine terminated VF in VST in sheep; and in swine, bretylium immediately produced sinus rhythm in one case; in another one, only delayed sinus rhythm was achieved but lasted a short time; in the last case ventricular tachycardia at 128 beats/min appeared. Because new drugs, which are really "defibrillating" drugs, are available (bretylium tosylate, bethanidine, clofilium, tricyclic antidepressants, phenotiazine derivatives), we plan to investigate these defibrillating drugs in isolated hearts, found in suitable animals like dogs (sheep and swine are difficult to defibrillate) and in humans during routine electropharmacological studies.

[Electrocardiogram simulation. A theoretical model of ischemia]. / La simulazione dell'elettrocardiogramma. Un modello teoretico di ischemia.

Using an electric circuit model, made of two segments formed of sections that behave electrically as subendocardial and subepicardial cells, we simulated myocardial ischemia in one of the two segments. The changes in the ST segment and in the T wave were obtained respectively by diminishing the intercellular potential from -90 mV to -60 mV and by shortening or prolonging the duration of action potentials. In order to simulate acute subendocardial, subepicardial and transmural ischemia, the potentials of the internal section, the outer section, and of both sections were diminished respectively. The ST segment appeared depressed both in the segment involved and in the undamaged one in subendocardial ischemia. In subepicardial ischemia it appeared elevated in the segment involved and was normal in the undamaged one. In transmural ischemia it was elevated in the segment with reduced potential and it was depressed in the undamaged segment. The depression of the ST segment in the undamaged part, both in subendocardial ischemia and in transmural ischemia, depends on the imbalance of the central point and therefore the whole subendocardial layer behaves electrically as if it really were ischemic. The T-wave changes in acute ischemia are in keeping with those of the ST segment.

Results, problems and perspectives with the autoregulating pacemaker.

Experimental in vitro testing coupled with animal and clinical studies have shown that a pH sensor may sense acute changes in pH occurring in response to exercise. This signal may in turn be used as a determinant for optimal pacing rate. Further investigation into membrane coating of electrodes and algorithm testing is necessary to maximize sensor response and control.

Preliminary experience with the pH-triggered pacemaker.

A cardiac pacemaker capable of responding to blood acidosis by change in its stimulation rate allows adjustment to a patient's metabolic needs. The blood pH is sensed by an iridium oxide electrode in the right atrium. During exercise, the venous pH decreases and the paced ventricular rate increases. If acidosis persists, the paced rate gradually returns to baseline and reaches it after about 70 minutes. A pH-triggered pacemaker has been implanted in a 72-year-old male. The pacemaker remained responsive one year after implant, increasing rate during exercise, cold pressor stress, ischemia of the arms and emotional stress.

[Clinical and biological aspects in patient with pH-triggered implanted pacemaker (author's transl)]. / Aspetti clinici e biologici in pazienti portatori di pacemaker pilotato dalle variazioni del pH ematico.

The Authors have selected the variations of blood pH to drive the pacing rate according to the new biological balance created by exercise. The clinical tests performed on the patients who have had a pH-triggered pacemaker implanted one year previously demonstrated that: a) during physical exercise there is an increase of cardiac rate triggered by the pacemaker, comparable with that noted when sinus rhythm is present; b) situations causing an increased production of cathecolamines and thus a pH variation--Cold Pressor Test, Ischaemic Test, as well as emotional stress--cause an increase of the stimulation rate of pH triggered pacemaker.