Coronary artery bypass grafting in patients with severe left ventricular dysfunction: predictive significance of left ventricular diastolic filling pattern.

AIMS: The aim of our study was to evaluate the influence of left ventricular (LV) diastolic filling impairment on postoperative results in patients (pts) with low LV ejection fraction (EF) (<35%) undergoing coronary artery bypass grafting (CABG). METHODS: The study covered 56 patients (mean age 58.9 +/- 17.1 years). Two dimensional Doppler echocardiographic investigations were performed pre- and 10-14 days post-CABG. Patients were divided into three groups according to the LV diastolic filling. RESULTS: Early postoperative mortality rate (including perioperative period and 2 weeks after surgery) was highest in the restriction group (33%) vs. pseudonormalization (12.5%) vs. impaired relaxation (13.6%). Postoperative cardiovascular complications rate was highest also in the restriction group, 55.5%, and did not differ between pseudonormalization (25%) and impaired relaxation group (27.2%). Logistic regression analysis showed that restrictive LV filling pattern, early diastolic filling deceleration time and LV end-diastolic diameter independently influence perioperative mortality. In the early postoperative period mean LV wall motion score (WMS) did not improve in 8/19 (42%), 6/14 (43%) and 8/12 (67%) patients, respectively, in the impaired relaxation, pseudonormalization and restriction group. CONCLUSIONS: In patients with severe LV dysfunction undergoing CABG, impaired relaxation and pseudonormal pattern of LV diastolic filling correlated with postoperative improvement in LV regional contraction, while restrictive pattern correlated with high early postoperative mortality, morbidity and minimal improvement in LV systolic function. Restrictive LV filling pattern, early diastolic filling deceleration time and LV end-diastolic diameter were found to be independent predictors of perioperative mortality.

Estimulaçäo com adaptaçäo de freqüência controlada pelo sistema nervoso autônomo - uma avaliaçäo clínica / ANS controlled rate-adaptive pacing: a clinical evaluation

Para o tratamento da incompetência cronotrópica, marcapassos com adaptaçäo em freqüência baseados em diferentes sinais de sensores têm sido desenvolvidos, visando restaurar o mecanismo fisiológico em malha fechada e utilizando informaçäo fornecida pelo sistema nervoso autônomo (SNA). A medida da impedância cardíaca unipolar permite a monitorizaçäo do estado de contraçäo do coraçäo, diretamente relacionado ao tônus simpático. Marcapassos uni ou bicamerais com sistemas responsivos controlados pelo SNA foram implantados em 262 pacientes em vários centros clínicos. Protocolos de exercícios clíncos, monitorizaçäo por Holter, testes de estresse psicológico e estudos adicionais visando uma variaçäo intencional do tônus simpático confirmaram a resposta fisiológica em freqüência para os vários tipos de mudanças hemodinâmicas.

Electrostimulated cardiomyoplasty: from experimental to clinical studies.

Cardiomyoplasty is a method for managing patients with dilated cardiomyopathy. We evaluated the means of carbon fiber electrode stimulation of the nerve to the latissimus dorsi muscle (LDM) in dogs to increase skeletal muscle contractility. Histochemical examination of biopsies of muscle electrically conditioned by a single pulse stimulator via the thoracodorsal nerve demonstrated transformation of muscle into fatigue resistant slow fibers without damage to muscle or nerve tissue. Canine experiments confirmed that carbon fibers are one of the best electrodes for chronic LDM stimulation. Between 1988 and 1992, we operated on ten patients, New York Heart Association (NYHA) Class III (4 patients) and Class IV (6 patients), with a mean left ventricular ejection fraction (LVEF) of 23%. The indications for cardiomyoplasty were idiopathic (7 patients) and ischemic (3 patients) cardiomyopathy refractory to maximum medical therapy. The operative procedure was performed via median sternotomy (5 patients) and left thoracotomy (5 patients). There was one operative mortality and two additional deaths during the late follow-up period. The mean postoperative LVEF increased to 27%. Functional class, quality-of-life, and ventricular performance were improved after cardiomyoplasty. Two of the surviving patients are in NYHA Class I, four in Class II, and one in Class III.

ANS controlled closed loop cardiac pacing - a multicenter study

A pacemaker system has been developed that in controlled by the autonomic nervous system (ANS). It measures the intracardiac impedance and derives a measure for the sympathetic drive from specific characteristics of the impedance curves. The pacing rate is adapted to this measure and thus is put under closed loop control of the ANS. In this paper the validity of the sensor principle and calculation of pacing rate were investigated. The formation of a closed-loop pacing rate regulation was demonstrad. Furthermore the entire system was validated in a clinical stting evaluating rate adaptive performance and benefit for the patient.

Doppler echocardiography during transesophageal atrial pacing in the detection of coronary artery disease. Stress Doppler echocardiography in the detection of coronary artery disease.

The aim of this study was to assess the applicability of the Doppler echocardiogram (EchoKG) during transesophageal atrial pacing (TAP) with respect to the detection of coronary artery disease (CAD). Aortic flow peak velocity (PV), mean acceleration (MA), stroke distance (SD), minute distance (MD) and time to PV were measured using pulsed Doppler EchoKG during sinus rhythm and at pacing rates of 120 and 140 bpm in 11 patients, taken as subjects, with CAD defined by coronary arteriography and 15 patients without CAD (the control group). Similar changes of PV, SD, MD and time to PV during TAP were observed in subjects with and without CAD. Only changes of MA were different between subjects with and without CAD:MA during TAP remained unchanged in the control group and decreased from 1055.2 +/- 49.7 cm/s2 (baseline) to 829.0 +/- 55.9 cm/s2 at pacing rate 140 bpm (p < 0.05) in subjects with CAD. On the basis of these data we suggest a new criterion for the detection of hemodynamically significant CAD: decrease of MA at a pacing rate of 140 bpm > 15% of initial value. Its specificity and sensitivity in the detection of CAD were respectively 87% and 82%. We conclude that the Doppler EchoKG during TAP is a relatively simple and reliable method for the diagnosis of CAD, and that the response of the Doppler EchoKG parameter of MA to TAP is a sensitive and specific index, useful for the detection of significant coronary artery stenosis.

Correlations between the localization of accessory atrioventricular pathway and Doppler indices of left ventricular output and function in patients with Wolff-Parkinson-White syndrome.

Left ventricular (LV) output and function was investigated, using pulsed Doppler echocardiography in 52 patients with various localizations of accessory AV pathway (AP) in sinus rhythm and during paroxysm of AV reentrant tachycardia. In patients with sinus rhythm and ventricular preexcitation the most marked decrease in LV output and function (reduced aortic flow peak velocity [PV], mean acceleration [MA], stroke distance [SD], minute distance [MD], and lengthened time to peak velocity [TTP]) was noted in the presence of right parietal AP and less marked changes (decreased MA, lengthened TTP)--in the presence of posteroseptal AP, in comparison with the controls (P less than 0.005). During antidromic tachycardia the pronounced decrease in PV, MA, SD, and MD was noted, especially in patients with left parietal and posteroseptal AP, while in the case of right parietal AP changes in MA and MD were insignificant. During orthodromic tachycardia the decrease in LV function was less marked and no significant differences in the magnitude of LV output and function changes were found in various localizations of AP, except MA, which was more severely decreased in patients with posteroseptal AP. We conclude, that the alterations in Doppler indices of LV output and function are related to the localization of AP during AV reentrant tachycardia and regular sinus rhythm.

Diagnosis and surgical treatment of ectopic atrial tachycardia.

Eighty-two patients with ectopic atrial tachycardia (EAT) were subjected to radical closed heart surgery (without cardiopulmonary bypass). The age of the patients ranged from 1 to 51 years. Permanent EAT was present in 19 patients, incessant EAT in 14, and paroxysmal EAT in 49 patients. Preoperative electrophysiological study included computed analysis of the P wave vector. Ectopic foci were established in the right atrium in 34 patients, in the left atrium in 11, in the interatrial septum in 32, and extracardially in 5 patients. For ablation or isolation of the foci, the cryogenic technique was used in 74 patients, cryo- and laser techniques in 4, and the laser technique alone in 1 patient. In 3 patients resection of the atrial auricles including the ectopic focus was undertaken. In 4 patients complete AV block was induced and a cardiac pacemaker implanted. After primary surgery, favourable results were obtained in 71 patients. In 11 patients recurrences were observed; 8 of these patients underwent successful repeat surgery. In 3 patients medical treatment was effective. Finally, the follow-up results have been promising-79 patients (96.4%) (including 4 patients in whom a complete AV block was created) have become arrhythmia-free. When EAT is resistant to medical treatment, closed heart ablation of the ectopic focus has proved to be safe (no mortality or morbidity) and effective. It can therefore be recommended not only for the termination of EAT but also for the prevention of dilated cardiomyopathy.