Electrical remodeling and cardiac dimensions in patients treated by cardiac resynchronization and heart failure controls

BACKGROUND: Cardiac resynchronization therapy (CRT) reduces the left ventricular diameter (LVEDD) in heart failure (HF) patients with left bundle branch block (LBBB). The study compares structural and electrical remodeling in HF patients on CRT and matched HF controls without LBBB. METHODS: In 42 patients (64 +/- 9 years left ventricular ejection fraction [LVEF] 25 +/- 8%, 16 coronary artery disease, 26 nonischemic cardiomyopathy, 21 with LBBB and CRT indication vs 21 controls [matched for gender, age, LVEF, and underlying disease]) an unpaced electrocardiogram (ECG) and echocardiogram were recorded at baseline (bl) and after 20.6 +/- 13.8 months (fup). LVEDD, left atrial (LA) width, mitral regurgitation (MR), P-wave, PR interval, QRS width, QRS vector, and QT interval were analyzed. RESULTS: LVEDD diminished with CRT (bl 68.7 +/- 10.3 vs fup 62.0 +/- 7.7 mm, P = 0.002). Controls showed no change (bl 64.1 +/- 9.4 vs fup 64.8 +/- 8.4 mm, P = n.s.). MR improved with CRT (bl 1.2 +/- 0.6 vs fup 0.8 +/- 0.7, P = 0.02), but not among controls. LA width tended to decrease on CRT (CRT bl 48.9 +/- 4.4 vs fup 46.9 +/- 7.2 mm, P = 0.17, controls bl 48.5 +/- 5.1 vs fup 47.5 +/- 6.5 mm, P = 0.49). PR interval lengthened in both groups (CRT bl 175 +/- 29 vs fup 188 +/- 30 ms, P = 0.03, controls bl 177+/-25 vs fup 187 +/- 19 ms, P = 0.27). QRS increased in both groups (CRT bl 165 +/- 22 vs fup 171 +/- 20 ms, P = 0.07, controls bl 111 +/- 17 vs fup 118 +/- 19 ms, P = 0.01). Analyses revealed no significant association of echocardiographic and ECG parameters. CONCLUSIONS: Despite LVEDD reduction with CRT, electrical activation does not recover. Electrical remodeling does not differ between LBBB patients under CRT and matched controls without CRT indication.     

The spectrum of inter- and intraventricular conduction abnormalities in patients eligible for cardiac resynchronization therapy

Although cardiac resynchronization therapy (CRT) has clearly demonstrated its clinical benefit in patients with congestive heart failure (CHF) and intraventricular conduction abnormalities, selection of eligible patients and/or optimal pacing site are still a matter of debate. The aim of the study was to analyze the spectrum of conduction abnormalities in CRT candidates. A total of 26 patients (mean age 62 +/- 9 years) with CHF and conduction disturbances (QRS > or = 130 ms) were studied. The underlying heart disease was dilated cardiomyopathy (DCM) (n = 12) or coronary artery disease (CAD) (n = 14). High density, left ventricular endocardial activation maps were constructed using an electroanatomic mapping system (CARTO). Based on endocardial activation patterns, left ventricular conduction abnormalities were classified as left bundle branch block (LBBB) (n = 9), nonspecific intraventricular conduction disturbances (n = 10), and the bifascicular block (n = 7). In DCM patients the endocardial activation sequences corresponded with a 12-lead ECG pattern with a homogeneous spread of activation wavefront and the latest activation laterally (LBBB) or anteriorly (bifascicular block), respectively. CAD patients presented with variable activation patterns that reflected the location of the postinfarct scar, and the 12-lead ECG was less predictive. Although there was a trend for longer QRS durations for DCM subjects (170 +/- 23 vs 156 +/- 23 ms, P = NS), left ventricular activation time was significantly longer in the CAD group (115 +/- 21 ms vs 134 +/- 23 ms, P < 0.05). CRT candidates represent a broad spectrum of conduction abnormality patterns with variable inter- and intraventricular activation delays. CAD subjects have more pronounced intraventricular conduction abnormality. The standard ECG is less reliable in the characterization of complex conduction abnormalities.     

QRS duration in high-resolution methods and standard ECG in risk assessment after first and recurrent myocardial infarctions

Background: Prolonged QRS duration (QRSd) is associated with increased mortality after myocardial infarction (MI). Only little data exist about its predictive ability and relationships to clinical variables in the present era of active treatment of myocardial ischemia and cardiac dysfunction. We investigated whether QRSd in high-resolution methods and standard ECG predict arrhythmic events and cardiac death in post-infarction patients with cardiac dysfunction and how it relates to clinical variables, with a special emphasis on history of previous MI.
Methods and Results: Patients (n = 158) with acute MI and cardiac dysfunction had magnetocardiography (MCG), signal-averaged ECG (SAECG), and ECG registered at discharge. Patients with a previous MI had significantly longer QRSd although their left ventricular function was almost similarly impaired. During the mean follow-up of 50 ± 15 (range 1–72) months, 32 patients died and 17 (53%) of the deaths were classified as cardiac. Eighteen patients had an arrhythmic event. QRSd >121 ms in MCG and >114 ms in SAECG were significant predictors of arrhythmic events and cardiac death, whereas QRSd in ECG predicted only cardiac death. In multivariate analysis, QRSd in MCG (hazard ratio (HR) = 3.6, P = 0.007) and SAECG (HR = 4.6, P = 0.016) predicted only arrhythmic events, whereas QRSd in ECG was an independent predictor of cardiac death.
Conclusions: Prolonged QRSd in MCG and SAECG are powerful indicators of the arrhythmia substrate in post-infarction patients with cardiac dysfunction, whereas prolonged QRSd in standard ECG associates with increased risk of cardiac death.     

Analysis of the electrocardiographic waveforms produced by right ventricular pacing: relation to the nonpaced patterns

Background: Ventricular aberrant conduction has a confounding effect on the known relationships between the electrocardiogram (ECG) and left ventricular (LV) mass. By relating the ECG of right ventricular pacing to LV mass and to nonpaced recordings, clarification of these effects might emerge.
Methods and Results: In 30 patients (age, 81 ± 7 years; 13 women) who had right ventricular paced ECGs and echocardiograms, 24 of who also had nonpaced ECGs, comparative analyses were performed. Although the nonpaced ECGs had strong correlations with various echocardiographic measurements, for paced ECGs, only QRS complex voltage and interventricular septal thickness (IVS) were significantly related. However, paced QRS complex voltage relationships correlated with those of nonpaced QRS complexes, ranging from an r = 0.54, P < 0.006, for the sum of the R in aVL and the S in V-3 to r = 0.78, P < 0.001, for the sum of the R in I and the S in III. Paced ECGs had a QRS complex with a greater spatial amplitude, a longer duration, and a more superior position, and had more deeply inverted T waves than nonpaced ECGs. The differences between the voltages of paced and nonpaced QRS complexes, moreover, diminished as LV mass and/or IVS increased. When compared with nonpaced ECGs, paced ECGs showed the most similarity to nonpaced ECGs having a left bundle branch block (LBBB) pattern. Except for the presence of more superiorly directed QRS complexes, paced impulses were not significantly different (P < 0.008) from nonpaced impulses having a LBBB pattern. Also, the nonpaced ECG pattern had no discernable effect on ECG produced by right ventricular (RV) pacing.
Conclusions: Despite having weak relations with echocardiographic measurements, the QRS complex voltage of the paced ECG correlated with those of nonpaced ECGs, and the voltage differences between them were smaller as LV mass increased.     

Sympathetic reflex control of subcutaneous blood flow in patients with congestive heart failure

Central and local regulation of forearm subcutaneous vascular resistance (FSVR) during postural changes were studied in congestive heart failure (CHF). Blood flow was measured by the local 133Xe-washout technique. Nine patients with severe CHF (baseline angiographic ejection fraction, 23 +/- 2%, mean +/- SEM; cardiac index, 2.2 +/- 0.2 litres min-1 m-2; increased left ventricular pressures and dimensions) were compared with seven control subjects who had normal cardiac performance. Baseline FSVR and plasma concentrations of noradrenaline and adrenaline were substantially higher in patients with CHF than control subjects. However, the patients, like control subjects, increased FSVR by 46 +/- 3% in response to increase in local venous transmural pressure and disclosed a normal response to decrease in forearm perfusion pressure. Both responses to changes in vascular transmural pressure were preserved after either proximal nervous blockade or local beta-receptor blockade. Central sympathetic stimulation was induced with use of 45 degrees upright tilt. Control subjects developed vasoconstriction (FSVR increased by 59 +/- 5%), which was completely abolished after proximal nerve blockade. Patients with CHF developed vasodilatation (FSVR decreased by 24 +/- 8%), which was not only abolished but reversed after proximal nerve blockade (FSVR increased by 22 +/- 7%), probably owing to the increased humoral vasoconstrictor activity. The paradoxical vasodilator response to central sympathetic stimulation in these patients was reversed after local beta-receptor blockade (FSVR increased by 19 +/- 9%). The local vasoconstrictor reflex responsiveness and intrinsic vascular reactivity were not affected by the augmented baseline sympathetic vasoconstrictor activity in patients with CHF.(ABSTRACT TRUNCATED AT 250 WORDS)     

aVR,An Index of all ECG Limb Leads,with Clinical Utility for Monitoring of Patients with Edematous States,Including Heart Failure

Background: Nonreproducibility of precordial electrocardiogram (ECG) leads in serial ECGs has led to emphasis on the limb leads for some applications. Since modern electrocardiographs measure leads I and II and calculate on line the other four limb leads, the former can substitute for the set of six limb leads. Furthermore, based on the mathematical relationship of lead aVR and leads I and II, it was hypothesized that aVR could be used as a representative index of the set of the six limb leads. The aim of this study was to evaluate whether ECG lead aVR could function as an index of all limb leads, in clinical electrocardiography. Methods: Automation‐derived and manually derived QRS voltage amplitude measurements of all limb leads in ECGs of a series of 100 randomly selected consecutive patients, and ECGs of 36 patients with various edematous states (EDST), congestive heart failure (CHF), or undergoing hemodialysis (HD), and aVR were inter‐correlated with the sums of leads I and II (ΣI&II), and the entire set of the six limb leads (Σ6LbLds). Results: Correlation of aVR with ΣI&II and Σ6LbLds was excellent (P < 0.00005); also, aVR was found to be a reliable index of the six limb leads in repeat ECGs in the patients with various EDST, CHF, or undergoing HD, in whom changes in aVR correlated with changes in patients’ body weight. Conclusion: aVR could be taken as an index of all ECG limb leads in analysis in general, and in monitoring patients with EDST, CHF, and HD in particular.     

Effect of the isolated left bundle branch block on systolic and diastolic functions of left ventricle.

BACKGROUND: We planned this study to evaluate the effects of left bundle branch block (LBBB) on systolic and diastolic functions of left ventricle (LV) that have not previously been investigated in detail. MATERIAL AND METHODS: Forty-five cases diagnosed as isolated LBBB according to the standard electrocardiographic criteria (group I, mean age: 60 +/- 12 years) were taken as the case group and 65 cases with normal conduction system (group II, mean age 58 +/- 14 years) were taken as the control group. Echocardiography was performed to all patients and coronary angiography was performed to 21 patients in group I and 35 patients in group II. In addition to standard systolic and diastolic function parameters, isovolumetric relaxation time (IRT), isovolumetric contraction time (ICT), and ejection time (ET) were measured by echocardiography, and the myocardial performance index (MPI) [(IRT+ICT)/ET] was calculated. LV end-diastolic pressure was calculated for the patients undergoing coronary angiography. RESULTS: In group I, LV end-systolic diameter was greater (3.1 +/- 0.4 cm vs 2.8 +/- 0.4 cm, P <.001) and ejection fraction was lower (64% +/- 6% vs 68% +/- 6%, P <.001) than those of group II. Rapid filling deceleration time and rate was markedly different in group I (respectively, 133 +/- 50 ms vs 166 +/- 24 ms, P <.001; 608 +/- 291 cm/s(2) vs 383 +/- 116 cm/s(2), P <.001). In addition, it was found that LBBB caused shortening of LV diastolic period and ET markedly (respectively, 347 +/- 116 ms vs 394 +/- 106 ms, P =.03; 255 +/- 40 ms vs 294 +/- 21 ms, P <.001) and prolongation of IRT and ICT (respectively; 124 +/- 36 ms vs 91 +/- 16 ms, 96 +/- 35 ms vs 38 +/- 9 ms, P <.001). The MPI was predominantly higher in group I (0.89 +/- 0.29 vs 0.40 +/- 0.06, P <.001). Invasively determined LV end-diastolic pressure was found higher in group I (14 +/- 3 mm Hg vs 10 +/- 3 mm Hg, P <.001). CONCLUSION: A marked elevation of the LV MPI and end-diastolic pressure, parallel to changes of conventional echocardiographic parameters, in patients with isolated LBBB points out that LBBB causes marked deterioration on LV systolic and diastolic functions.     

Intracoronary infusion of dobutamine to patients with and without severe congestive heart failure. Dose-response relationships, correlation with circulating catecholamines, and effect of phosphodiesterase inhibition.

We infused dobutamine into the left main coronary artery of 24 patients with severe congestive heart failure (CHF) and 8 normal subjects without hemodynamic dysfunction. The maximal +dP/dt response to intracoronary (IC) dobutamine in CHF patients was only 37% of that in normals. This decrease in maximal response was not associated with a rightshift in the EC50 for dobutamine's effect on +dP/dt, or a decrease in the affinity of myocardial beta adrenergic receptors for dobutamine determined in vitro. In nine of the CHF patients, IC dobutamine infusion was followed by IC infusion of the phosphodiesterase inhibitor milrinone, and subsequently, by a second IC infusion of dobutamine. After IC milrinone, the increase in +dP/dt caused by IC dobutamine (74 +/- 10%) was significantly greater than that caused by the first infusion of dobutamine (52 +/- 11%; P less than 0.003) or milrinone (42 +/- 6%; P less than 0.001). Resting plasma norepinephrine was markedly elevated in CHF patients (837 +/- 208 ng/liter), but not in normal subjects (142 +/- 32 ng/liter); and the increase in +dP/dt caused by IC dobutamine was inversely related to resting plasma norepinephrine levels (r = -0.653; P less than 0.001). IC dobutamine caused a dose-related decrease in plasma norepinephrine (maximal effect, -160 +/- 31 ng/liter; P less than 0.001). Thus, (a) the maximal inotropic response to dobutamine is markedly depressed in patients with severe CHF, and is significantly greater after pretreatment with the phosphodiesterase inhibitor milrinone; (b) the impairment in inotropic response to dobutamine is inversely related to circulating norepinephrine levels; and (c) myocardial stimulation by dobutamine results in withdrawal of sympathetic tone.     

Neural networks--a diagnostic tool in acute myocardial infarction with concomitant left bundle branch block

The prognosis of acute myocardial infarction (AMI) improves by early revascularization. However the presence of left bundle branch block (LBBB) in the electrocardiogram (ECG) increases the difficulty in recognizing an AMI and different ECG criteria for the diagnosis of AMI have proved to be of limited value. The purpose of this study was to detect AMI in ECGs with LBBB using artificial neural networks and to compare the performance of the networks to that of six sets of conventional ECG criteria and two experienced cardiologists. A total of 518 ECGs, recorded at an emergency department, with a QRS duration > 120 ms and an LBBB configuration, were selected from the clinical ECG database. Of this sample 120 ECGs were recorded on patients with AMI, the remaining 398 ECGs being used as a control group. Artificial neural networks of feed-forward type were trained to classify the ECGs as AMI or not AMI. The neural network showed higher sensitivities than both the cardiologists and the criteria when compared at the same levels of specificity. The sensitivity of the neural network was 12% (P = 0.02) and 19% (P = 0.001) higher than that of the cardiologists. Artificial neural networks can be trained to detect AMI in ECGs with concomitant LBBB more effectively than conventional ECG criteria or experienced cardiologists.     

Prolonged paced QRS duration as a predictor for congestive heart failure in patients with right ventricular apical pacing

BACKGROUND: The recent studies showed that right ventricular (RV) pacing was associated with worsening of heart failure. The aim of this study is to clarify the clinical significance of paced QRS duration during RV pacing to predict congestive heart failure (CHF) patients. METHODS AND RESULTS: This study enrolled in 92 patients with atrioventricular block who underwent initial pacemaker implantation. The paced QRS duration was automatically obtained by electrocardiography immediately after pacemaker implantation and then by routine attendance at a pacemaker clinic every 3 months. The paced QRS duration was positively correlated with left ventricular end-diastolic dimension (P < 0.05) and left ventricular end-systolic dimension (P < 0.05), and tended to negatively correlate with left ventricular ejection fraction (P = 0.0507). The paced QRS duration immediately after pacemaker implantation was 170.4 +/- 18.9 ms. During a mean follow-up period of 53 +/- 16 months, 16 patients developed CHF. We selected as a cut-off value the nearest whole number (190 ms) that was one standard deviation greater than the mean, and divided into two groups according to baseline paced QRS duration. Patients with a paced QRS duration of <190 ms comprised group A (n = 77, nine of which developed CHF) and the remainder comprised group B (n = 15, seven of which developed CHF). Prolonged paced QRS duration (> or =190 ms) was associated with a significant increase in the overall morbidity of CHF (P < 0.05). Additionally, paced QRS duration significantly prolonged during the follow-up period among group A patients with CHF (P < 0.05), but did not change among patients without CHF. CONCLUSION: We concluded that paced QRS duration can be a useful indicator of impaired left ventricular function in patients with RV pacing. Even in patients whose paced QRS duration is relatively shorter, progressive prolongation of paced QRS duration can predict the development of CHF.     

Ventricular coupling of electrical and mechanical dyssynchronization in heart failure patients

We studied the relationships of electrical and mechanical synchronization in patients with heart failure (CHF) and various degree of ventricular conduction delays. Ninety-two CHF patients (60 +/- 13 years old, LVEF < 45%), NYHA II-III-IV, and 35 age-matched control subjects were studied with angioscintigraphic phase analysis. We measured ejection fractions (LVEF, RVEF) and calculated the total activation time for the left (TtLV) and right ventricle (TtRV), and the synchronization time between right and left ventricle (TRVLV), and between LV apex and base (Tab). Patients were divided into three groups according to QRS duration: group 1 < 120 ms (n = 28), group 2 < 150 ms (n = 23), group 3 > or = 150 ms (n = 41). In group 1: LVEF = 31.1 +/- 10.9%, RVEF = 30.1 +/- 12.6%, TtLV = 204 +/- 70 ms, TtRV = 183 +/- 61 ms, TRVLV = 7 +/- 33 ms, Tab = 29 +/- 23 ms. In group 2, these were: 27.8 +/- 9.1%, 27.8 +/- 8.8%, 227 +/- 95 ms, 248 +/- 137 ms, 35 +/- 42 ms*, and 39 +/- 53 ms respectively. In group 3: LVEF = 20.5 +/- 9.5%t, RVEF = 28.4 +/- 16.1%, TtLV = 304 +/- 155 mst, TtRV = 234 +/- 106 mst, TRVLV = 64 +/- 42 mst, and Tab = 67 +/- 48 ms*, all P < 0.001 versus controls *P < 0.05 versus G1, tP < or = 0.01 versus G1. A significant relation links QRS to both inter- and intraventricular asynchrony (TRVLV: r = 0.65; TtLL: r = 0.70, Tab: r = 0.60), and to LV function (r = 0.72); while LVEF relates more closely to intraventricular asynchrony: TtLV (r = 0.52), TtLL (r = 0.67), than to interventricular asynchrony: TRVLV (r = 0.48); P < 0.01, P < or = 0.001. In CHF patients, electromechanical and contractile alterations are coupled; regional activation may be an early parameter allowing the detection of ventricular dyssynchronization.     

Uncovering Heart Failure in Patients with a History of Pulmonary Disease: Rationale for the Early Use of B-type Natriuretic Peptide in the Emergency Department

Plasma B-type natriuretic peptide (BNP) can reliably identify acute congestive heart failure (CHF) in patients presenting to the emergency department (ED) with acute dyspnea. Heart failure, asthma, and chronic obstructive pulmonary disease (COPD) are syndromes where dyspnea and wheezing are overlapping signs, and hence, these syndromes are often difficult to differentiate. OBJECTIVE: To determine whether BNP can distinguish new-onset heart failure in patients with COPD or asthma presenting with dyspnea to the ED. METHODS: The BNP Multinational Study was a seven-center prospective study of 1,586 adult patients presenting to the ED with acute dyspnea who had blinded BNP levels measured on arrival with a rapid, point-of-care device. This study evaluated the 417 patients with no previous history of heart failure and a history of asthma or COPD as a subgroup from the 1,586 adult patients in the BNP Multinational Study. The reference standard for CHF was adjudicated by two independent cardiologists, also blinded to BNP results, who reviewed all clinical data and standardized CHF scores. RESULTS: A total of 417 subjects (mean age 62.2 years, 64.4% male) had a history of asthma or COPD without a history of CHF. Of these, 87/417 (20.9%, 95% CI = 17.1% to 25.1%) were found to have CHF as the final adjudicated diagnosis. The emergency physicians identified a minority, 32/87 (36.8%), of these patients with CHF. The mean BNP values (+/- SD) were 587.0 +/- 426.4 and 108.8 +/- 221.3 pg/mL for those with and without CHF (p < 0.0001). At a cutpoint of 100 pg/mL, BNP had the following decision statistics: sensitivity 93.1%, specificity 77.3%, positive predictive value 51.9%, negative predictive value 97.7%, accuracy 80.6%, positive likelihood ratio 4.10, and negative likelihood ratio 0.09. If BNP would have been added to clinical judgment (high > or = 80% probability of CHF), at a cutpoint of 100 pg/mL, 83/87 (95.4%) of the CHF subjects would have been correctly diagnosed. Multivariate analysis found BNP to be the most important predictor of CHF (OR = 12.1, 95% CI = 5.4 to 27.0, p < 0.0001). In the 87 subjects found to have CHF, 39.0%, 22.2%, and 54.8% were taking angiotensin-converting enzyme inhibitors (ACEIs), beta-blockers (BBs), and diuretics on a chronic basis, respectively. CONCLUSIONS: The yield of adding routine BNP testing in patients with a history of asthma or COPD in picking up newly diagnosed CHF is approximately 20%. This group of patients presents a substantial therapeutic opportunity for the initiation and chronic administration of ACEI and BB therapy, as well as other CHF management strategies.     

Level of activities associated with mobility during everyday life in patients with chronic congestive heart failure as measured with an "activity monitor".

BACKGROUND AND PURPOSE: Because of dyspnea and fatigue, patients with congestive heart failure (CHF) may be restricted in the performance of normal everyday activities. The aim of this study was to obtain a preliminary indication of the level of activities associated with mobility during everyday life and between-day variance in activities in patients with mild to moderate CHF as measured with an "Activity Monitor." SUBJECTS AND METHODS: The "Activity Monitor" is based on long-term (>24 hours) ambulatory monitoring of signals from accelerometers fixed to the subject's body during everyday activities with the aim of assessing the level of activities associated with mobility. Measurements were obtained over 3 days from 5 male subjects with CHF (mean age=64 years, SD=5, range=59-72) and over 2 days from 5 matched comparison subjects (mean age=65 years, SD=4, range=61-71). RESULTS: Mean duration of movement-related activities (walking, cycling, or general movement) (expressed as a percentage of the duration of the measurement day) was lower in the subjects with CHF (X=3.9, SD=1.5, range=2.2-6.7) than in the comparison subjects (X=11.3, SD=3.0, range=6.6-14.1). In the patients, between-day variance was smaller for different weekdays (eg, Monday versus Tuesday) than for similar weekdays (eg, 2 Mondays) (1.11% and 7.28%, respectively). DISCUSSION AND CONCLUSION: The results show how activities associated with mobility during everyday life may be restricted in people with CHF.     

Differentiating Systolic from Diastolic Heart Failure Using Impedance Cardiography

OBJECTIVE: Differentiating systolic from diastolic congestive heart failure (CHF) is often difficult in the ED. Impedance cardiography (IC) allows for the noninvasive evaluation of systolic function and measurement of diastolic time intervals. This study was designed to assess the ability of IC to accurately measure isovolumic relaxation time (IVRT) and determine relative cardiac contractility, thereby differentiating systolic from diastolic mechanisms in acute CHF. METHODS: In an evaluation of the technique, the average differences in the diastolic time intervals measured in normal subjects by both IC tracings and phonocardiography were compared. Likewise, the average Heather index (HI) of patients with known systolic dysfunction (ejection fraction < 30% by echo-cardiography) was compared with the mean HI measured in the normal subjects. In a retrospective analysis, the clinical performance of the method was examined by extracting the values of IVRT and HI from IC tracings of patients presenting with CHF. The determined IVRT and HI values were then correlated to clinical markers for diastolic and systolic dysfunction. RESULTS: Analysis of 280 IC tracings in eight healthy volunteers revealed an average difference of 0.0075 seconds (95% CI = -0.0067 to 0.0217) when IVRT intervals measured by phonocardiography and IC are compared. The HI in this normal group averaged 14.2 (95% CI = 9.4 to 19.0), contrasting to the much lower value of 2.8 (95% CI = 1.98 to 3.62) seen in eight subjects with documented systolic dysfunction. In 26 patients with decompensated CHF, there was a close correlation (r = 0.81) of the measured IVRT to left ventricular hypertrophy by voltage criteria and while a fall in the HI was correlated with intravascular volume expansion. Though there was considerable overlap (46%) in mechanisms of CHF, 35% of the patients were found to have only systolic dysfunction (HI < 5 and IVRT < 0.125), while 19% had a predominantly diastolic etiology (IVRT > 0.125 and HI > 5) for their failure. CONCLUSION: IC measures of contractility and diastolic time intervals are a potentially effective method for differentiating the dominant mechanisms of CHF in the emergent setting and categorizing CHF patients into different subsets.     

Differential diagnosis of slow/slow atrioventricular nodal reentrant tachycardia from atrioventricular reentrant tachycardia using concealed posteroseptal accessory pathway by 12-lead electrocardiography

Slow pathways are used as both antegrade and retrograde conduction pathway in slow/slow atrioventricular nodal reentrant tachycardia (SS-AVNRT), and patients with SS-AVNRT have tachycardia ECGs mimicking atrioventricular reentrant tachycardia using concealed posteroseptal accessory pathway (PS-AVRT). Therefore, SS-AVNRT can be misdiagnosed as PS-AVRT, and the differential diagnosis is clinically important. Standard 12-lead ECGs during tachycardia were analyzed in patients with SS-AVNRT (n = 10) and PS-AVRT (n = 10). All these patients were diagnosed by electrophysiological study and underwent successful catheter ablation. Differences of the RP' intervals (dRP') between V1 and the inferior leads were evaluated. SS-AVNRT had significantly longer RP' intervals measured in V1 (167 +/- 25.2 vs 137 +/- 26.8 ms, SS-AVNRT vs PS-AVRT, respectively, P = 0.02), longer dRP' between V1 and II (dRP'[V1-II], 37 +/- 14 vs 17 +/- 6.7 ms, P = 0.0007), longer dRP'[V1-III] (39 +/- 14 vs 17 +/- 9.9 ms, P = 0.0011), and longer dRP'[V1-aVF] (39 +/- 13 vs 20 +/- 9.5 ms, P = 0.0008). The following criteria were suggested for differential diagnosis of SS-AVNRT from PS-AVRT: dRP'[V1-II] >25 ms (sensitivity and specificity: 80% and 100%, respectively), dRP'[V1-III] >23 ms (90% and 90%), dRP'[V1-aVF] >30 ms (90% and 90%). Differences of the RP' intervals between V1 and the inferior leads in the tachycardia ECGs were useful for differential diagnosis of SS-AVNRT from PS-AVRT.     

Pulmonary vein vestibule ablation for the control of atrial fibrillation in patients with impaired left ventricular function

INTRODUCTION: Congestive heart failure (CHF) and atrial fibrillation (AF) are frequently linked, and when associated produce additive deleterious effects. In this prospective study, the effects of catheter ablation for AF in patients with impaired left ventricular (LV) function are presented. METHODS: Baseline data and clinical outcome have been prospectively collected in 105 consecutive patients who underwent pulmonary vein ablation for the control of AF. We evaluated 40 patients affected by LV dysfunction with ejection fraction (EF)<40% and compared them to the remaining 65 patients with normal ventricular function in terms of changes in LV function, maintenance of sinus rhythm, and quality of life during follow-up. RESULTS: After a mean follow-up of 14+/-2 months, 87% of patients with impaired LV function and 92% of patients with normal ventricular function were in sinus rhythm, with or without antiarrhythmic therapy (P=NS). A significant improvement in LVEF and fractional shortening was documented in patients with CHF (33+/-2% vs 47+/-3%, and 19+/-4% vs 30+/-3%, P<0.01 for both comparisons). Evaluation of exercise capacity and quality of life documented better improvements in patients with CHF compared to patients without CHF. CONCLUSIONS: Catheter ablation in patients with LV dysfunction is feasible, not associated with higher procedural complications, and provides a significant improvement in LV performance, symptoms, and quality of life during follow-up.     

Influence of congestive heart failure on prazosin kinetics.

The kinetics of oral prazosin was studied in 10 healthy normal subjects (NS) and in 9 patients with congestive heart failure (CHF). NS received a single 5-mg dose, and blood concentrations of prazosin (CB) were measured, using a specific HPLC assay, during an 8-hr period. CHF patients received a 2-mg dose after which CB was measured for 10 hr. These patients then received 2 to 5 mg prazosin every 8 hr for 48 hr. After the last dose of prazosin, CB was measured for 24 hr. After the initial dose, time to peak CB did not differ significantly between that of the NS (123 +/- 19 SEM min) and of patients with CHF (132 +/- 31.3 min). AUC/mg prazosin was greater (p less than 0.001) in patients with CHF (3,385 +/- 380 Ng x min/ml) than in NS (1,603 +/- 208 ng x min/ml). Elimination of prazosin from blood was slower in CHF patients (t1/2 = 374 +/- 33.4 min) than in NS (t1/2 = 144.5 +/- 4.3 min) (p less than 0.001). These data suggest that in patients with CHF the elimination of prazosin is substantially slower than in NS and therefore higher steady-state prazosin concentrations can be expected in CHF patients than in NS.     

Brain natriuretic peptide in patients with ST segment elevation myocardial infarction. Prognostic significance

AIM: To study changes in the level of brain natriuretic peptide (BNP) in patients with ST segment elevation myocardial infarction (MI) to assess prognostic value of this marker and validity of its use as a criterion of therapy effects. MATERIAL AND METHODS: The trial enrolled 217 patients (102 males and 15 females, mean age 63.96 +/- 0.73 years) admitted to hospital on MI day 1. Plasmic level of BNP (Nt-proBNP) was measured 1, 7, 21 days, 8 weeks and 6 months after MI. RESULTS: The severity of chronic cardiac failure (CCF) correlated with peptide content in the blood: it was by 46.6% higher in patients with chronic heart failure (CHF) functional class (FC) IV than in those with CHF FC I (p = 0.047), in FC III by 27.5% higher (p = 0.003) and in FCII--by 13.1% (p = 0.485). Initially high levels of BNP correlated with early development of CHF (R2 = 0.9058), with hospital lethality (in the deceased--1040.0 +/- 65.8 fmol/ml, in the survivors--461.4 +/- 26.2 fmol/ml, r = 0.35, p < 0.001) and overall lethality. A more pronounced decrease in the peptide level was seen in patients after 3 week intake of beta-adrenoblocker esmolol than in those who did not take it (by 125.2 vs 74.1 fmol/ml, respectively, p < 0.05). By BNP level, efficacy of perindopril vs captopris was studied (group 1 and group 2, respectively), in patients with ejection fraction under 40%. Initially, BNP levels were elevated and did not differ among the groups. On MI week 8 there was a decrease in the level of BNP by 25.4% (p = 0.004), 19.1% (p = 0.06) in groups 1 and 2, respectively. Six months after MI patients of group 1 had normal levels of BNP (up to 269.6 +/- 18.3 fmol/l). CONCLUSION: Measurements of BNP levels are useful for prediction of poor prognosis in MI patients and evaluating efficacy of the treatment.     

Measuring baroreflex sensitivity from the gain function between arterial pressure and heart period

We tested an innovative approach for estimating baroreflex sensitivity (BRS) from the gain function between spontaneous oscillations of systolic arterial pressure (SAP) and heart period (HP). The major goal was to assess the practical implications of abandoning the classical coherence criterion (> or =0.5) as regards measurability of BRS, and agreement with values of BRS obtained using the phenylephrine test (Phe-BRS). We studied 19 normal subjects, 44 patients with a history of previous myocardial infarction (MI) and 45 patients with chronic heart failure (CHF). The experimental protocol included recording of SAP and HP for 10 min of supine rest, and evaluation of Phe-BRS. From resting SAP and HP, the gain and coherence functions were computed. The new BRS index was obtained in all subjects by averaging the gain function over the whole low-frequency band (0.04-0.15 Hz) (whole-band average BRS, WBA-BRS). WBA-BRS was 7.4 (5.8-10.8) ms/mmHg [median (25th-75th percentile)] in normal controls, 3.1 (1.4-5.4) ms/mmHg in MI patients (P<0.001 compared with normals) and 5.0 (3.2-6.9) ms/mmHg in CHF patients (P<0.01 compared with normals). Using the coherence criterion, BRS could be measured in only 43% and 49% of MI and CHF patients respectively, and the proportion of the low-frequency band contributing to the measurement was 21% (14-47%) and 29% (16-35%) respectively. The correlation between WBA-BRS and Phe-BRS was 0.47, 0.63 and 0.36 in the normal, MI and CHF groups respectively (all P<0.001). The relative bias of WBA-BRS was -5.2 ms/mmHg (P<0.001) in normals, -1.4 ms/mmHg (P=0.004) in MI patients and -1.0 ms/mmHg (P=0.11) in CHF patients. The limits of agreement were -13 to 2.6, -7.4 to 4.6 and -9.3 to 7.3 ms/mmHg in the normal, MI and CHF groups respectively. Thus the WBA-BRS method standardizes the computation of BRS among subjects, and dramatically increases its measurability in subjects with pathology compared with the classical spectral technique based on the coherence criterion. Compared with Phe-BRS, WBA-BRS tends to give negatively biased results. The correlation and the magnitude of the limits of agreement between the two methods are similar to those observed previously using coherence-based spectral methods.     

Pharmacokinetics and protein binding of cefpiramide in patients with alcoholic cirrhosis

The pharmacokinetics of cefpiramide, a new cephalosporin, were investigated after a single 1 gm intravenous injection in 11 patients with alcoholic cirrhosis and compared with those of 11 healthy subjects. In patients with cirrhosis the plasma elimination half-life was three times longer than that in normal subjects. The total plasma clearance was decreased significantly (p less than 0.001): 12.3 +/- 6.5 ml/min in patients and 25.6 +/- 4.6 ml/min in healthy volunteers, respectively. The urinary excretion of unchanged drug (percent of intravenous dose) for patients (69.8% +/- 29.9%) was statistically higher (p less than 0.01) than that for subjects (16.2% +/- 3.9%). The renal elimination became increasingly important with hepatic impairment. Protein binding of cefpiramide was reduced significantly in the group with cirrhosis. The average unbound fraction was 10.4% +/- 9.5% in patients with cirrhosis and 1.9% +/- 0.3% in normal subjects (p less than 0.01). Because the rate of elimination from plasma in patients is slower, the dosage regimen of cefpiramide would probably be modified in cirrhosis.