Loading...
(1/4972) Effect of coronary occlusion on left ventricular function with and without collateral supply during beating heart coronary artery surgery.

OBJECTIVE: To study the effects of coronary occlusion and collateral supply on left ventricular (LV) function during beating heart coronary artery surgery. DESIGN: Prospective intraoperative study, performed at baseline, during wall stabilisation, coronary artery occlusion, and 2 and 10 minutes after reperfusion. Transoesophageal M mode echocardiograms, simultaneous high fidelity LV pressure, and thermodilution cardiac output were measured. LV anterior wall thickening, thinning velocities, thickening fraction, regional work, and power production were derived. Asynchrony during the isovolumic periods was quantified as cycle efficiency. SETTING: Tertiary referral cardiac centre. PATIENTS: 14 patients with stable angina, mean (SD) age 62 (7) years, undergoing left anterior descending artery grafting using the "Octopus" device. RESULTS: Collaterals were absent in nine patients and present in five. Epicardial stabilisation did not affect LV function. Results are expressed as mean (SD). Coronary occlusion (15.6 (2) minutes) depressed anterior wall thickening (1.4 (0.6) v 2.6 (0.6) cm/s) and thinning velocities (1.4 (0.5) v 3.0 (0.6) cm/s), regional work (2.2 (0.8) v 4.6 (0.6) mJ/cm2), and power (21 (4) v 33 (5) mW/cm2) in patients without collaterals (p < 0.05 for all), but only wall thinning (3.5 (0.5) v 4.8 (0.5) cm/s, p < 0.05) in patients with collaterals. All returned to baseline within 10 minutes of reperfusion. Cycle efficiency and regional work were impaired at baseline and fell during occlusion, regardless of collaterals. Within 10 minutes of reperfusion both had increased above baseline. CONCLUSIONS: Coronary occlusion for up to 15 minutes during beating heart coronary artery surgery depressed standard measurements of systolic and diastolic anterior wall function in patients without collaterals, but only those of diastolic function in patients with collaterals. Regional synchrony decreased in both groups. All disturbances regressed within 10 minutes of reperfusion.  (+info)

(2/4972) QT dispersion in patients with chronic heart failure: beta blockers are associated with a reduction in QT dispersion.

OBJECTIVE: To compare QT dispersion in patients with impaired left ventricular systolic function and in matched control patients with normal left ventricular systolic function. DESIGN: A retrospective, case-control study with controls matched 4:1 for age, sex, previous myocardial infarction, and diuretic and beta blocker treatment. SETTING: A regional cardiology centre and a university teaching hospital. PATIENTS: 25 patients with impaired left ventricular systolic function and 100 patients with normal left ventricular systolic function. MAIN OUTCOME MEASURES: QT and QTc dispersion measured by three methods: the difference between maximum and minimum QT and QTc intervals, the standard deviation of QT and QTc intervals, and the "lead adjusted" QT and QTc dispersion. RESULTS: All measures of QT/QTc dispersion were closely interrelated (r values 0.86 to 0.99; all p < 0.001). All measures of QT and QTc dispersion were significantly increased in the patients with impaired left ventricular systolic function v controls (p < 0.001): 71.9 (6.5) (mean (SEM)) v 46.9 (1.7) ms for QT dispersion, and 83.6 (7.6) v 54.3 (2.1) ms(-1-2) for QTc dispersion. All six dispersion parameters were reduced in patients taking beta blockers (p < 0.05), regardless of whether left ventricular function was normal or impaired-by 9.4 (4.6) ms for QT dispersion (p < 0.05) and by 13.8 (6. 5) ms(-1-2) for QTc dispersion (p = 0.01). CONCLUSIONS: QT and QTc dispersion are increased in patients with systolic heart failure in comparison with matched controls, regardless of the method of measurement and independently of possible confounding factors. beta Blockers are associated with a reduction in both QT and QTc dispersion, raising the possibility that a reduction in dispersion of ventricular repolarisation may be an important antiarrhythmic mechanism of beta blockade.  (+info)

(3/4972) Enteroviral RNA replication in the myocardium of patients with left ventricular dysfunction and clinically suspected myocarditis.

BACKGROUND: Previous studies dealing with the detection of enteroviral RNA in human endomyocardial biopsies have not differentiated between latent persistence of the enteroviral genome and active viral replication. Enteroviruses that are considered important factors for the development of myocarditis have a single-strand RNA genome of positive polarity that is transcribed by a virus-encoded RNA polymerase into a minus-strand mRNA during active viral replication. The synthesis of multiple copies of minus-strand enteroviral RNA therefore occurs only at sites of active viral replication but not in tissues with mere persistence of the viral genome. METHODS AND RESULTS: We investigated enteroviral RNA replication versus enteroviral RNA persistence in endomyocardial biopsies of 45 patients with left ventricular dysfunction and clinically suspected myocarditis. Using reverse-transcriptase polymerase chain reaction in conjunction with Southern blot hybridization, we established a highly sensitive assay to specifically detect plus-strand versus minus-strand enteroviral RNA in the biopsies. Plus-strand enteroviral RNA was detected in endomyocardial biopsies of 18 (40%) of 45 patients, whereas minus-strand RNA as an indication of active enteroviral RNA replication was detected in only 10 (56%) of these 18 plus-strand-positive patients. Enteroviral RNA was not found in biopsies of the control group (n=26). CONCLUSIONS: These data demonstrate that a significant fraction of patients with left ventricular dysfunction and clinically suspected myocarditis had active enteroviral RNA replication in their myocardium (22%). Differentiation between patients with active viral replication and latent viral persistence should be particularly important in future studies evaluating different therapeutic strategies. In addition, molecular genetic detection of enteroviral genome and differentiation between replicating versus persistent viruses is possible in a single endomyocardial biopsy.  (+info)

(4/4972) Endogenous endothelin-1 depresses left ventricular systolic and diastolic performance in congestive heart failure.

Endothelin-1 (ET-1) is a positive inotrope in normal hearts; however, the direct cardiac effects of endogenous ET-1 in congestive heart failure (CHF) are unknown. We evaluated the cardiac responses to endogenous ET-1 using an ETA and ETB receptor blocker (L-754,142) in seven conscious dogs before and after pacing-induced CHF. Before CHF, when the plasma ET-1 was 7.3 +/- 1.7 fmol/ml, L-754,142 caused no significant alterations in heart rate, left ventricular (LV) end-systolic pressure, total systemic resistance, and the time constant of LV relaxation (tau). LV contractile performance, measured by the slopes of LV pressure (P)-volume (V) relation (EES), dP/dtmax-end-diastolic V relation (dE/dtmax), and stroke work-end-diastolic V relation, was also unaffected. After CHF, when the plasma ET-1 was significantly increased to 14.1 +/- 3.0 fmol/ml (p <.05), L-754,142 produced a significant decreases in LV end-systolic pressure (101 +/- 11 versus 93 +/- 8 mm Hg) and total systemic resistance (0.084 +/- 0.022 versus 0.065 +/- 0.15 mm Hg/ml/min). The tau (42 +/- 12 versus 38 +/- 10 ms), mean left atrial P (22 +/- 5 versus 18 +/- 4 mm Hg) (p <.05), and minimum LVP were also significantly decreased. After CHF, the slopes of P-V relations, EES (3.4 +/- 0.4 versus 4.8 +/- 0.8 mm Hg/ml), dE/dtmax (42.4 +/- 7.8 versus 50.0 +/- 7.8 mm Hg/s/ml), and stroke work-end-diastolic V relation (58.1 +/- 3.3 versus 72.4 +/- 5.2 mm Hg) (p <.05) all increased after L-754,142, indicating enhanced contractility. Before CHF, low levels of endogenous ET-1 have little cardiac effect. However, after CHF, elevated endogenous ET-1 produces arterial vasoconstriction, slows LV relaxation, and depresses LV contractile performance. Thus, elevated endogenous ET-1 may contribute to the functional impairment in CHF in this canine model.  (+info)

(5/4972) Racial differences in the outcome of left ventricular dysfunction.

BACKGROUND: Population-based studies have found that black patients with congestive heart failure have a higher mortality rate than whites with the same condition. This finding has been attributed to differences in the severity, causes, and management of heart failure, the prevalence of coexisting conditions, and socioeconomic factors. Although these factors probably account for some of the higher mortality due to congestive heart failure among blacks, we hypothesized that racial differences in the natural history of left ventricular dysfunction might also have a role. METHODS: Using data from the Studies of Left Ventricular Dysfunction (SOLVD) prevention and treatment trials, in which all patients received standardized therapy and follow-up, we conducted a retrospective analysis of the outcomes of asymptomatic and symptomatic left ventricular systolic dysfunction among black and white participants. The mean (+/-SD) follow-up was 34.2+/-14.0 months in the prevention trial and 32.3+/-14.8 months in the treatment trial among the black and white participants. RESULTS: The overall mortality rates in the prevention trial were 8.1 per 100 person-years for blacks and 5.1 per 100 person years for whites. In the treatment trial, the rates were 16.7 per 100 person-years and 13.4 per 100 person-years, respectively. After adjustment for age, coexisting conditions, severity and causes of heart failure, and use of medications, blacks had a higher risk of death from all causes in both the SOLVD prevention trial (relative risk, 1.36; 95 percent confidence interval, 1.06 to 1.74; P=0.02) and the treatment trial (relative risk, 1.25; 95 percent confidence interval, 1.04 to 1.50; P=0.02). In both trials blacks were also at higher risk for death due to pump failure and for the combined end point of death from any cause or hospitalization for heart failure, our two predefined indicators of the progression of left ventricular systolic dysfunction. CONCLUSIONS: Blacks with mild-to-moderate left ventricular systolic dysfunction appear to be at higher risk for progression of heart failure and death from any cause than similarly treated whites. These results suggest that there may be racial differences in the outcome of asymptomatic and symptomatic left ventricular systolic dysfunction.  (+info)

(6/4972) Prevalence of hibernating myocardium in patients with severely impaired ischaemic left ventricles.

OBJECTIVE: Severe impairment of left ventricular (LV) contraction is associated with an adverse prognosis in patients with ischaemic heart disease. Revascularisation may improve the impaired LV contraction if hibernating myocardium is present. The proportion of patients likely to benefit from this intervention is unknown. Therefore, the prevalence of hibernating myocardium in patients with ischaemic heart disease and severe impairment of LV contraction was assessed. DESIGN: From a consecutive series of patients undergoing coronary angiography for the investigation of chest pain or LV impairment, all patients with ischaemic heart disease and an LV ejection fraction (LVEF) < or = 30% were identified. These patients underwent positron emission tomography (PET) to detect hibernating myocardium, identified by perfusion metabolism mismatch. SETTING: A teaching hospital directly serving 500,000 people. RESULTS: Of a total of 301 patients, 36 had ischaemic heart disease and an LVEF < or = 30%. Twenty-seven patients had PET images, while nine patients were not imaged because of emergency revascularisation (three), loss to follow up (one), inability to give consent (four), and age < 50 years (one, ethics committee guidelines). Imaged and non-imaged groups were similar in LV impairment, demographic characteristics, and risk factor profile. Fourteen patients (52% of the imaged or 39% of all patients with ischaemic heart disease and LVEF < or = 30%) had significant areas of hibernating myocardium on PET. CONCLUSION: It is possible that up to 50% of patients with ischaemic heart disease and severely impaired left ventricles have hibernating myocardium.  (+info)

(7/4972) Echo derived variables predicting exercise tolerance in patients with dilated and poorly functioning left ventricle.

OBJECTIVE: To determine whether resting echo derived measurements predict exercise tolerance and its interrelation with heart rate response and ventilation drive in patients with systolic left ventricular disease. DESIGN: Prospective echocardiographic examination followed by cardiopulmonary exercise testing. SETTING: A tertiary referral centre for cardiac diseases. SUBJECTS: 21 patients (11 with coronary artery disease, 10 with idiopathic dilated cardiomyopathy) with end diastolic dimension > 6.4 cm, shortening fraction < 25%, and in sinus rhythm. There were 11 age matched normal controls. RESULTS: In the patients, peak oxygen consumption (mVo2) correlated with right ventricular long axis excursion (r = 0.62); 65% of the variance in mVo2 was predictable using a multivariate model with right ventricular long axis excursion and peak lengthening rate, and peak mitral atrial filling velocity as independent variables. Aetiology was not an independent predictor, although the right ventricular long axis excursion (mean (SD)) was greater in patients with idiopathic dilated cardiomyopathy than in those with coronary artery disease (2.4 (0.5) cm v 1.6 (0.5) cm, p < 0.001). Peak heart rate correlated with duration of mitral regurgitation (r = -0.52) and the slope of ventilation against CO2 production correlated with M mode isovolumic relaxation time (r = 0.61). CONCLUSIONS: In patients with systolic left ventricular dysfunction, more than half the variance in exercise tolerance can be predicted by factors measured on echocardiography at rest, particularly right ventricular long axis excursion.  (+info)

(8/4972) Acute saline infusion reduces alveolar-capillary membrane conductance and increases airflow obstruction in patients with left ventricular dysfunction.

BACKGROUND: Impaired alveolar-capillary membrane conductance is the major cause for the reduction in pulmonary diffusing capacity for carbon monoxide (DLCO) in heart failure. Whether this reduction is fixed, reflecting pulmonary microvascular damage, or is variable is unknown. The aim of this study was to assess whether DLCO and its subdivisions, alveolar-capillary membrane conductance (DM) and pulmonary capillary blood volume (Vc), were sensitive to changes in intravascular volume. In addition, we examined the effects of volume loading on airflow rates. METHODS AND RESULTS: Ten patients with left ventricular dysfunction (LVD) and 8 healthy volunteers were studied. DM and Vc were determined by the Roughton and Forster method. The forced expiratory volume in 1 second (FEV1), vital capacity, and peak expiratory flow rates (PEFR) were also recorded. In patients with LVD, infusion of 10 mL. kg-1 body wt of 0.9% saline acutely reduced DM (12.0+/-3.3 versus 10.4+/-3.5 mmol. min-1. kPa-1, P<0.005), FEV1 (2.3+/-0.4 versus 2.1+/-0.4 L, P<0.0005), and PEFR (446+/-55 versus 414+/-56 L. min-1, P<0.005). All pulmonary function tests had returned to baseline values 24 hours later. In normal subjects, saline infusion had no measurable effect on lung function. CONCLUSIONS: Acute intravascular volume expansion impairs alveolar-capillary membrane function and increases airflow obstruction in patients with LVD but not in normal subjects. Thus, the abnormalities of pulmonary diffusion in heart failure, which were believed to be fixed, also have a variable component that could be amenable to therapeutic intervention.  (+info)