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Biomedical subjects

R Candinas

Publications and source records attributed to R Candinas.

90 records · Page 5Linked to original sources
PubMed1993

[Heart pacemaker therapy: a guideline for clinical practice].

Pacemakers have evolved enormously over the past 15 years because of technical developments in the field of microprocessors. Implantation of physiologic dual chamber systems (DDD pacemakers) have gained growing importance. The goal of therapy with modern pacemakers is to relieve symptoms under rest as well as under hemodynamic load. Next to indications for and explications on the function of the various systems (single and dual chamber systems, rate responsive pacemakers) this article covers hemodynamic consequences of pacemaker implantation. Particular reference is made to the follow-up of patients with pacemakers and to the possibility of external interference with these devices. A glossary of pacemaker therapy is given in the appendix.

Aftercare↗
PubMed1993

[Surgery for arrhythmia in patients with therapy-resistant ventricular tachycardia].

We reviewed the data of 42 consecutive patients (mean age 55 +/- 12 years) who underwent surgery for control of recurrent drug-refractory ventricular arrhythmia. A history of myocardial infarction was present in 38 patients, 4 patients had congenital heart disease (2 aneurysms, 1 right ventricular dysplasia, 1 hamartoma). The mean LV ejection fraction was 40 +/- 14%. At preoperative electrophysiologic study, ventricular tachycardia was inducible in 32 of 33 patients. The mean heart rate was 188/min. A mean of 3.3 +/- 2.1 antiarrhythmic drug trials were ineffective. The most frequently performed surgical procedure (n = 36) was visually guided subendocardial resection, alone or in combination with cryothermal ablation. In 30 patients additional aneurysmectomy was performed. A mean of 1.9 +/- 1.4 coronary arteries in 32 patients were bypassed. The overall in-hospital mortality (30 days) was 9.5% (1 arrhythmic death, 1 pump failure, 1 sepsis, 1 hemorrhagic shock). We found 2 significant (p < 0.05) predictors of perioperative mortality: recent myocardial infarction and patient's age. During a mean follow-up of 33 months (range 1 to 90), there were 3 sudden cardiac deaths and 6 nonfatal recurrences of ventricular tachycardia which were subsequently prevented with antiarrhythmic drug therapy. Thus, the overall success in control of arrhythmia was 92%, in 59% by surgery alone. Survival was 79% at 2 years after surgery and 63% at 5 years. We conclude that patients who have successful subendocardial resection and aneurysmectomy for control of ventricular arrhythmia have an excellent chance of arrhythmia-free survival and a relatively good prognosis.

Adolescent↗
PubMed1993

[Right ventricular dysplasia (right ventricular cardiomyopathy). Clinical aspects, diagnosis and course in 15 patients from the Zurich area].

Fifteen patients (8 men, 7 women) with right ventricular dysplasia (RVS) from the greater Zürich area are described. Two thirds of these patients were younger than 30 years at first manifestation. 12 presented with ventricular tachycardia of left bundle branch block type. Other forms of arrhythmia (supraventricular tachycardia, sinus node dysfunction) or condition disturbances were documented in 9 subjects. 6 patients had additional symptoms of congestive heart failure; in 3 of them this was the only symptom. 12-lead ECG at rest showed precordial T-negativity (1 pacemaker ECG not interpretable) in 14/15 subjects. Signal averaged ECG revealed late potentials as well as spectral turbulence in the Y or Z leads. Echocardiography yielded typical local abnormalities in the whole study cohort and all but 2 patients showed decreased right ventricular ejection fraction and right heart dilatation. Moreover, left ventricular ejection fraction was concomitantly impaired in 6 subjects. 4 of these 6 individuals suffered from further impairment of left ventricular function within a time period of 19 to 47 months. Recurrent ventricular tachycardia was documented in 11 patients. 2 subjects underwent heart transplantation because of severe progressive right heart failure. One subject died shortly after diagnosis and autopsy confirmed nearly total absence of right ventricular myocardium. This extreme form of right ventricular dysplasia corresponds to Uhl's anomaly. Thus, recurrent ventricular arrhythmias, in particular ventricular tachycardia of left bundle branch block type, together with precordial T-negativity without signs of ischemic heart disease, is highly suggestive of RVD. Echocardiography allows reliable diagnosis. Concomitant left ventricular involvement is frequent. Considering that the etiology and pathogenesis of this disease are unknown, the term right ventricular cardiomyopathy, rather than right ventricular dysplasia, seems more accurate.

Adult↗
PubMed1993

[Clinical late results following surgical ablation of an accessory atrioventricular connection in Wolff-Parkinson White syndrome].

All patients operated because of WPW-syndrome between 1980 and 1990 at the University clinics of Zürich were followed up by clinical examination and by electrocardiography. Relief from symptoms (tachycardia, vertigo and/or syncopes) was defined as "symptomatic" success, lack of preexcitation in the ECG at rest as "surgical" success. Overall 56 patients (40 men, 16 women) aged from 13 to 66 years had been operated in the stated time period. Before operation 52 of these patients had pre-excitations in the ECG, 54 had tachycardia and 23 had syncopes. None of the patients died from the operation. In order to localize the AAVVs epicardial cartography was performed in all patients during operation before the AAVVs were cut through an endocardial access. The follow-up was possible after an average interval of 5.5 years (1-120 months) in 50 of the 56 patients. One patient died 10 years after operation from heart failure. 6 patients were reported to be out of the country. The follow-up revealed symptomatic success of the intervention, defined as absence of tachycardia, in 88% (44 out of 50). In 84% (42 out of 50) also a surgical success of the operation was found. In these patients the accessory atrio-ventricular bundle had been successfully ablated, and they were free of tachycardia and of preexcitation in the ECG. Two patients with persisting preexcitation remained free of clinical symptoms. Insofar the rate of symptomatic success was higher than the rate of surgical success. Summarizing the results surgical transsection (ablation) of an accessory atrioventricular bundle in patients with WPW-syndrome is a good therapeutic option with favorable long term success. It has today still its place--in selected cases--as alternative to the now available radio-frequency ablation.

Adolescent↗
PubMed1993

Premature ICD battery depletion due to a defective lead adapter component: usefulness of extensive data logging.

Described herein is the usefulness of extensive data logging of third generation ICDs in a patient with premature ICD battery depletion due to a defective pace/sensing lead component. Due to noise artifacts, VT/VF detections occurred leading to inappropriate patient shock discharges and 2,267 internal charge dumps within 2 weeks. During manual manipulations at the ICD site, real-time intracardiac electrocardiogram and event markers revealed noise artifacts that were interpreted as VT/VF. Radiography confirmed slight movement of the pace/sensing lead pin out of the Y-adapter. Therefore, the design of adapter systems without screw fixation should be reviewed to ensure lead integrity. In the case of sudden increases in VT/VF recognition, defective sensing components must be considered.

Electric Power Supplies↗
PubMed1993

[Arrhythmias and heart failure].

Numerous factors contribute to the genesis of arrhythmias and sudden cardiac death in patients with congestive heart failure. Fibrosis of myocardium, ischemia, dilatation of the ventricles and atria, electrolyte imbalance, and neurohumoral factors are examples. Various drugs used in the treatment of congestive heart failure can also precipitate serious arrhythmias. The role of antiarrhythmics, including amiodarone, is still controversial. Judicious antiarrhythmic therapy involves weighing potential benefits of such therapy against risks, such as worsening heart failure or proarrhythmia. In patients with heart failure antiarrhythmic drugs should only be used for symptomatic arrhythmias. Low-dose beta-blockade offers a promising measure for the prevention of sudden cardiac death even in patients with symptomatic congestive heart failure.

Anti-Arrhythmia Agents↗
PubMed1993

[Therapy of atrial fibrillation with class III anti-arrhythmia agents].

Medical treatment of atrial fibrillation has been carried out most frequently with digoxin, quinidine, propafenone or flecainide. In spite of unequivocal efficacy, the use of class I antiarrhythmic agents is the subject of considerable controversy. In addition to increased mortality in patients with ventricular arrhythmias after myocardial infarction, proarrhythmic effects with flecainide have also been described in patients with supraventricular arrhythmias. A meta-analysis of long-term treatment of atrial fibrillation with quinidine disclosed that the mortality in those treated with quinidine at 2.9% was significantly higher than those receiving placebo at 0.8%. In consideration of the prevailing uncertainty with the use of class I antiarrhythmic agents, class III antiarrhythmic drugs such as sotalol and amiodarone have been administered for supraventricular arrhythmias with increasing frequency. Treatment of atrial fibrillation with sotalol Sotalol is a noncardioselective beta-adrenergic receptor blocker with antiarrhythmic properties of class III. This drug prolongs the duration of the action potential and the refractory periods in atrial and ventricular myocardium and slows the AV-conduction as well as the sinus node rate. On oral administration, there is good resorption and a half-time of seven to 18 hours. The effective oral dose varies between 80 and 320 mg/12 hours. For conversion of acute supraventricular arrhythmias, an i.v. bolus of 0.5 to 1.5 mg/kg has been used. The results of clinical studies with sotalol in the treatment of atrial fibrillation are shown in Table 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone↗
PubMed1992

[Clinical aspects of arrhythmias].

Arrhythmias are frequent and occur in normal individuals as well as in patients with structural heart disease. In supraventricular arrhythmias the indication for treatment is mainly based on symptoms. In atrial fibrillation the thromboembolic risk has to be taken into account. In ventricular arrhythmias, especially in combination with significant structural heart disease, prognostic considerations play an important role in decision-making.

Arrhythmias, Cardiac↗
PubMed1992

[Electrophysiology: indications for and results in programmed stimulation].

Since the early seventies electrophysiology is a diagnostic tool to evaluate mechanisms of arrhythmias and to control drug therapy. Advances in technology have led to newer methods, such as radiofrequency ablation and the use of implantable defibrillators. These techniques as well as their diagnostic, prognostic and therapeutic indications will be discussed.

Arrhythmias, Cardiac↗
PubMed1992

[Drug therapy in supraventricular arrhythmia].

In view of their potentially dangerous proarrhythmic effects, antiarrhythmic drugs should only be prescribed for patients with poorly tolerated symptomatic supraventricular arrhythmias. The choice of a suitable preparation depends not only on the type of arrhythmia, but also on the underlying heart disease and left-ventricular function. Digoxin, verapamil, sotalol and quinidine remain first-line drugs, while in view of recent trials the type-1c antiarrhythmics (flecainide) should only be given in cases resistant to other agents. Amiodarone is also an important and efficacious "reserve" antiarrhythmic, which has to be utilized at low doses to avoid its well-known side effects.

Amiodarone↗
PubMed1992

Predictors of surgical mortality and long-term results of endocardial resection for drug-refractory ventricular tachycardia.

The results of surgical therapy performed in 51 consecutive patients with ventricular tachycardia were reviewed to determine short- and long-term predictors of success of such therapy in preventing recurrences of life-threatening ventricular arrhythmias. Of 41 patients (80%) who survived surgery, 40 had postoperative programmed stimulation and, of these patients, 78% (n = 31) had no inducible ventricular tachycardia on no antiarrhythmic therapy. This group had a very low incidence of arrhythmia recurrence, with only one nonfatal episode of ventricular tachycardia after a mean follow-up of 41 +/- 30 months. In contrast, two of the nine patients (22%) who had inducible arrhythmias postoperatively had cardiac arrest (p = 0.12). Multivariate analysis identified two significant predictors of perioperative mortality in our patients: increased duration of cardiopulmonary bypass time and increased baseline pulmonary capillary wedge pressure. It is concluded that (1) patients who do not have inducible ventricular tachycardia after arrhythmia surgery have a very low incidence of recurrent arrhythmia and (2) prolonged time of cardiopulmonary bypass and increased pulmonary capillary wedge pressure are predictive of perioperative mortality.

Adult↗
PubMed1991

[Clinical experience with a second-generation cardioverter-defibrillator].

Implantable cardioverter defibrillators (ICD's) are effective for reducing mortality in refractory malignant ventricular arrhythmias (MVA). Second generation ICD's (Telectronics Guardian 4202/4203) were implanted in 7 patients (all male, mean age 58.1 years) with ventricular fibrillation (VF) in 2, ventricular tachycardia (VT) in 1, and both VF and VT in 4. Underlying heart disease was coronary artery disease in 4 patients, and valvular heart disease, dilated cardiomyopathy and no obvious cause (documented primary VF, reproducible at electrophysiologic study) in 1 patient each. Mean ejection fraction was 40 +/- 14%. Mean defibrillation threshold of the two epicardial patches at implantation by means of median sternotomy was 18 +/- 9 joule, and patch impedance 35 +/- 7 ohms. Post defibrillation bradypacing via epicardial electrode was programmed in 5 patients (70%). Mean follow-up was 10.1 months (1-25 months). Successful defibrillation of 28 spontaneous VT/VF episodes was noted in 2 patients, while the other 5 have had no further episodes of MVA so far. One device was explanted following tissue necrosis at the battery site after a MVA-recurrence-free interval of 15 months. The reconfirmation algorithm prevented false shock delivery in 2 patients.

Cardiac Pacing, Artificial↗
PubMed1990

Role of the sympathetic nervous system in the genesis of ventricular arrhythmia.

Activation of the sympathetic nervous system is an important factor in the genesis of ventricular arrhythmias in patients with impaired ventricular function. Such patients have an appropriate substrate that is capable of generating rhythm abnormalities, which may be related to enhanced automaticity, triggered automaticity, and reentrant mechanisms; all three mechanisms are markedly potentiated by the action of catecholamines. Additionally, the sympathetic nervous system can provoke the development of hypokalemia and ischemia (which can independently lead to the occurrence of rhythm disturbances), and catecholamines may negate the beneficial electrophysiological actions of antiarrhythmic drugs. A substantial amount of experimental data implicates the sympathetic nervous system as a potent stimulus for ventricular tachyarrhythmias and sudden cardiac death, especially in the setting of myocardial ischemia. Two important mechanisms that have been identified include 1) enhanced sympathetic outflow from the central nervous system and 2) nonuniform myocardial denervation resulting in beta-receptor up-regulation and catecholamine hypersensitivity in the infarct zone. Disruption of sympathetic neural innervation of the heart and the use of beta-blocking agents may reduce the occurrence of sudden death and improve survival in animal models of arrhythmias and in some subsets of patients, including those with the long QT syndrome, a recent myocardial infarction, and perhaps those with a cardiomyopathy. The mechanism of this beneficial effect remains to be defined.

Adrenergic beta-Antagonists↗
PubMed1987

[Morphology of the sick sinus node].

Normally functioning sino-atrial nodes have been compared with nodes of patients with sick sinus syndrome (SSS) in a study of 65 autopsy hearts. 40-50 numbered sections of each node in constant intervals were compared quantitatively by light microscope. The results were: 1. Sino-atrial nodes of patients with SSS and normally functioning nodes are of the same size. 2. In patients with SSS the sino-atrial node has a higher content of collagenous fibres. 3. Sino-atrial node and conduction system tend to become sick at the same time. 4. This study offers no clue as to the etiology of SSS, but ischemia can be ruled out as the cause in most cases.

Humans↗
PubMed1979

[Progress and developments in insulin therapy].

BANTING and BEST revolutionized diabetes therapy with the discovery of insulin 57 years ago. Since then, progress in this area has been slow despite tremendous reseach efforts. The subcutaneous injection of a depot insulin does not provide optimal control of blood sugar. True progress has been brought about by intravenous insulin administration for the management of diabetic coma. The authors do not recommend ultra low dose therapy. The prognosis of diabetic coma is much better than 20 years ago, in particular because of much improved and continuous supervision of the circulation (CVP, ECG, K+ etc.). Pancreas and islet transplantation fail in man due to immunological rejection. The "artificial pancreas" with a glucose sensor is useful for research purposes, and for controlling blood sugar for a few days at most. The implantable glucose sensor is not yet in sight. The authors have treated diabetics successfully with a programmable flexible open loop infusion program. The basal insulin infusion rate can be varied from 0.25 to 2 U/h, and rectangular one hour extra insulin infusions between 2 and 10 U/h are superimposed by pushing a button on the steering unit. The pump automatically switches back to the basal rate after one hour. No hypoglycemic reactions have been observed in patients on ths program on the ward or at home. At present, technical problems with the catheter remain to be solved before this simple therapeutic approach can be applied routinely.

Adolescent↗
PubMedDate not supplied

Surgical management of infected permanent transvenous pacemaker systems: ten year experience.

BACKGROUND: Between January 1985 and June 1995, more than 1800 consecutive patients underwent implantation of a new permanent cardiac pacemaker at our institution. Thirty-six patients (0.02%) had 45 reinterventions for infected pacemaker systems. METHODS: in group A, 24 of 27 patients received simultaneous implantation of a new pacemaker. One had reimplantation of the same pacemaker in the same pocket, and two did not require reimplantation. The leads were retained in 19 (70%) of the patients. In group B, nine patients underwent cardiopulmonary bypass or "pursestring" surgery for removal of an infected pacemaker; a new epicardial pacemaker system was simultaneously implanted in seven patients. RESULTS: Identification of an infectious agent failed in 17 patients (47%), and Staphylococci were found in 15 patients (42%). The time from pacemaker implantation to onset of infection ranged from 1 month to 11 years (mean 31 months; median 19 months) and the time from onset of infection to surgical treatment from 1 month to 7 years (mean 7 months; median 2 months). The mean follow-up time is 74 months (range, 1 month to 10 years; median 5 years). There were 9 reoperations in 3 patients (16%) of group A for recurrent infection of their retained leads ultimately necessitating the use of open cardiac surgery. There was no early death; six patients died late due to unrelated causes. CONCLUSIONS: Complete removal of all pacemaker leads is recommended; open heart surgery with the use of cardiopulmonary bypass is indicated in selected cases and is effective and safe.

Adolescent↗