Cardiac resynchronization therapy (CRT) - A new option in the treatment ofend-stage heart failure

Background: With regard to epidemiological aspects, heart failure has been shown an increasing incidence in constrast to coronary artery disease which counts decreasingly due to secondary and primary prevention. The present d ata show an incidence for heart failure of 2% per year. 4-5 million people are newly affected by the disease. The prognosis is limited after diagnosis is confirmed. According to the US Framingham study, the median life expect ancy is 3.2 and 5.4 after diagnosis for male and female, respectively. For patients in an advanced stage of the disease the mortality rate is 27% with in 3 years. AV Sequential Pacing. The introduction of AV sequential pacing by the Austr ian group of Margarete Hochleitner in 1992 showed an improved left ventricu lar systolic function, an improved clinical benefit in terms of NYHA classi fication, an enhanced left ventricular ejection fraction, an improved systo lic a nd diastolic blood pressure, a reduction of the heart-chest relations hip as well as a reduction of the resting hart rate and the echocardiograph ic dimension parameters. Studies: First experimental approach for biventricular stimulation, which m eans the simultaneous activation of the right and the left chamber, relied on the observation of a distorted ventricular activation due to the presenc e of a bundle branch block. The bundle branch block is a result of the dila tation of the myocardial fibers, death of myocardial cells which are replac ed by fibrous tissue. Resynchronization of both ventricles was associated w ith an improved left ventricular function and improved diastolic relaxation . Clinical studies of patients with heart failure, severe left ventricular systolic dysfunction, and left bundle branch block have shown that systolic function can be improved by electrically stimulating the site of late acti vation. The magnitude of the improvement seems to be associated with the du ration of the intrinsic surface ORS complex and whether the ventricle ipsi lateral with the conduction defect is stimulated. The effect of Ventricular resynchronization therapy was optimized by timing of atrioventricular acti vation associated with a decrease in both systolic and diastolic mitral reg urgitation. Conclusion: The prognosis of patients with end-stage heart failure is limit ed by two determinants: myocardial pump failure and sudden (arrhythmogenic) cardiac death. Due to the fact that the incidence for sudden cardiac death is considerably high in patients with end-stage heart failure it is reason able to include the implantation of cardioverters/defibrillaters (ICD) in t he concept of biventricular stimulation.