[Myocardial lactate extraction during programmed ventricular stimulation and its value for etiologically-related therapy of ischemic ventricular tachyarrhythmia]. / Myokardiale Laktatextraktion während programmierter Ventrikelstimulation und ihre Bedeutung für die Kausaltherapie ischämisch induzierter ventrikulärer Tachyarrhythmien.

UNLABELLED: Ischemia is considered to be one of the most important trigger mechanisms of ventricular tachyarrhythmias, i.e., tachycardia (VT) and fibrillation (VF) in coronary artery disease (CAD). The aim of the study was 1) to investigate the relationship between ischemia and inducibility of VT/VF, and 2) to address the question, if removal of ischemia leads to suppression, resp. noninducibility of arrhythmias. In 30 patients (pts) with CAD (healed myocardial infarction in 73%, acute myocardial infarction excluded) and sustained malignant ventricular arrhythmias (VF in 47%, VT in 37%, and arrhythmogenic syncope in 16%) the myocardial lactate extraction (MLE) was calculated by measuring the arterio venous coronary lactate difference simultaneously during programmed ventricular stimulation. Eighteen pts (group A, "lactate-positive") showed a significant decrease of MLE from +16 +/- 13% at rest to -18 +/- 24% during stimulation just before induction of VT/VF (p < 0.0005). During recovery up to 10 min following termination of VT/VF MLE returned to normal range (+19 +/- 16%). In 12 pts (group B, "lactate-negative") MLE showed no significant change between rest, stimulation, and recovery. Compared to group B pts, group A pts demonstrated a significantly higher number and degree of coronary lesions as well as regions with reversible ischemia during 201Tl- scintigraphy. Lactate-positive pts presented spontaneous arrhythmias of higher frequency and had usually a two- or three-vessel disease, while lactate-negative pts presented arrhythmias of lower frequency and had more often a one-vessel disease with ventricular aneurysm. 17/18 (94%) group A pts underwent coronary bypass grafting (11) or balloon angioplasty (6) and were rendered noninducible during post interventional PVS in 94%, showing also a normalized MLE in 87% of cases. In group B only 4/12 pts were suitable for revascularization and could be rendered noninducible in only 50% of cases. With respect to the success-rate of the anti-ischemic therapy in terms of arrhythmia suppression, a lactate-positive result during primary PVS had a sensitivity of 89%, a specificity of 75%, a positive predictive value of 94%, and a negative predictive value of 60%. IN CONCLUSION: in about 60% of pts with VT/VF and significant CAD a correlation between ischemia and inducibility could be demonstrated. MLE during PVS has a highly significant predictive value for the effect of an antiischemic intervention on arrhythmia induction.

Late potentials and heart rate variability in heart muscle disease.

To elucidate the incidence and clinical significance of ventricular late potentials (LP) and reduced heart rate variability (HRV) in primary and secondary heart muscle disease, 157 patients with dilated cardiomyopathy (DCM, n = 19), chronic myocarditis (MC, n = 50), hypertrophic cardiomyopathy (HCM, n = 27) and systemic hypertension (HT, n = 61) were studied. LP measured by the signal averaging technique were found in 24% of the total study group--47% of the patients with DCM, 28% with MC, 29% with HCM and 10% with HT. Complex ventricular arrhythmias were detected during Holter monitoring in 56% of patients with DCM, in 41% with MC, in 21% with HT and in 16% with HCM. An electrophysiological study was performed in a total of 75 patients. Non-sustained or sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) were inducible during programmed ventricular stimulation in 32% of patients with MC, in 30% with HT, in 20% with DCM and in 17% with HCM. The total duration of the signal-averaged, filtered QRS complex was the only independent predictive factor for severe arrhythmic events and sudden cardiac death. HRV measured in 39 patients were most reduced in patients with DCM (RR interval standard deviation (HRV-SD) 39 +/- 23 ms), followed by 44 +/- 16 ms in patients with HCM, 45 +/- 28 ms in patients with HCM and 67 +/- 51 ms in patients with HT. A significant reduction in the HRV-SD below 30 ms was recorded in 24% of patients measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophysiological and therapeutic implications of cardiac arrhythmias in hypertension.

UNLABELLED: Hypertension, especially if associated with left ventricular hypertrophy (LVH), is a risk factor in complex ventricular arrhythmia (VA) and sudden cardiac death (SCD). To determine the effectiveness of the clinical use of programmed ventricular stimulation (PVS) we studied 40 symptomatic hypertensive patients after excluding coronary heart disease (CHD), as characterized by dizziness and palpitation, syncope, aborted SCD and/or documented complex VA. PVS revealed a normal result, i.e. a maximum of six ventricular echobeats, in 70% (group A) and a pathological result, i.e. ventricular tachycardia (VT) or fibrillation (VF) in 30% (group B). Both groups differed significantly with respect to LV (left ventricular) muscle mass: 158 +/- 45 (A) vs. 222 +/- 112 (B) g.m-2, LVEF (left ventricular ejection fraction): 71 +/- 17% (A) vs. 47 +/- 18% (B) and LV end-systolic volume index: 34 +/- 25 (A) vs. 63 +/- 27 (B) ml.m-2. Coronary reserve was comparably reduced in both groups: 2.6 +/- 1.0 (A) vs. 2.3 +/- 0.6 (B). In 3/8 (37%) patients with aborted SCD and VT/VF the clinical VA (2/2 VT and 1/6 VF) could be induced, whereas in the remaining five patients nsVT or no complex VA was induced. The therapeutic regimen included no drugs in 30%, beta-blockers in 50%, serial drug testing in 12% and implantation of an automatic cardioverter defibrillator (AICD) in 8% of patients. Ventricular late potentials (LPs), detected by the signal averaging electrocardiogram, represent zones of delayed myocardial activation, which may become an origin of ventricular tachycardias. Three criteria constitute a positive LP: (1) QRS duration greater than 114 ms, (2) root mean square voltage of the last 40 ms less than 20 microV and (3) duration of low amplitude signal below 40 microV greater than 38 ms. To look for the prognostic value of LP in hypertension we investigated 43 hypertensive patients without evidence of CHD. All three criteria were positive in 4/43 patients (9%), three of them demonstrating inducible monomorphic VT during PVS. 17/30 patients (56%) with LVH had at least one positive criterion, whereas only one out of 13 patients without left ventricular hypertrophy (8%) had one positive criterion. Symptomatic patients presenting with syncope, aborted SCD or documented VT/VF differed significantly from patients without symptoms or complex arrhythmias in regard to all three criteria. CONCLUSION: In hypertensive heart disease clinical arrhythmias as well as the result of electrophysiological testing are closely related to left ventricular performance and hypertrophy.(ABSTRACT TRUNCATED AT 400 WORDS)