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PubMed2003

Biphasic response to dobutamine predicts improvement of left ventricular dysfunction after revascularization: correlation with positron emission and rest-redistribution 201Tl tomographies.

BACKGROUND: Dobutamine echocardiography (DSE), positron emission tomography (PET) and 201Tl-single photon emission computed tomography (SPECT) have been used to identify myocardial viability. There are few reports, however, that compare high doses DSE with myocardial metabolic and perfusion imaging techniques in the same patient population. The aim of this study was to determine the correlation between high doses DSE, metabolic PET and 201Tl-SPECT imaging to predict the recovery of function after revascularization in patients with severe left ventricular (LV) dysfunction. METHODS: Twenty-five patients underwent DSE (up to 40 microg/kg/min), rest and 4-hour redistribution 201Tl SPECT, rest 13N-ammonia and 18fluoro-deoxy-glucose PET imaging and coronary angiography 7-10 days before surgical revascularization. A follow-up 2D-echocardiography was performed 6 weeks after surgery. RESULTS: Of the 109 successfully revascularized segments with severe dysfunction, 62 (57%) improved. LV ejection fraction increased from 30 +/- 10% to 42 +/- 13 at follow-up (p < 0.05). 201Tl SPECT, PET and the presence of contractile reserve determined by DSE had a similar sensitivity (77-87%) to predict recovery of function, but specificity was higher for the PET mismatch pattern and biphasic DSE (85-89%) than for any of the 201Tl viability patterns (19-64%). The highest positive predictive values were obtained by biphasic DSE and PET mismatch pattern (78-79%) compared to all other criteria (54-67%). In a multivariate model, which included evidence of viability by all imaging modalities, biphasic response was the best predictor of regional recovery of function (Odds ratio, OR: 9.9, 95% confidence intervals, 95% CI: 3.5-27.8). CONCLUSIONS: Although DSE and PET had overall comparable results, the presence of contractile reserve by the biphasic response to dobutamine was a best predictor for the improvement of LV contractile function in this group of patients.

Cardiotonic Agents↗
PubMed1989

Relation of exercise capacity to resting arterial oxygen transport in left ventricular dysfunction.

To determine the relation between arterial oxygen delivery and exercise capacity, 38 men with mild to severe chronic left ventricular (LV) dysfunction (New York Heart Association functional class II or III) were studied. All diagnostic cardiac catheterizations were performed 1 week before the exercise tests and the mean LV ejection fraction was 0.30 +/- 0.07. All patients performed graded treadmill exercise tests according to the Sheffield protocol. The relation between supine resting hemodynamic measurements did not correlate with exercise duration. Only resting cardiac output (r = 0.54, p less than 0.01) and systemic vascular resistance (r = -0.51, p less than 0.05) correlated weakly with exercise duration. However, arterial oxygen transport was highly related to exercise duration (r = 0.76, p less than 0.001) and peak oxygen consumption (r = 0.71, p less than 0.001). Thus, knowledge of calculated arterial oxygen transport can predict exercise capacity in patients with chronic LV dysfunction.

Adult↗
PubMed1997

Significance of persistent left ventricular dysfunction during recovery after dobutamine stress echocardiography.

OBJECTIVES: This study sought to determine the duration of new or worsening left ventricular regional wall motion abnormalities (RWMAs) after dobutamine stress echocardiography (DSE) and their relation to the extent of coronary artery disease (CAD). BACKGROUND: Despite extensive reports on DSE, little is known about the duration of new or worsening RWMAs during recovery. We hypothesized that the persistence of RWMAs during recovery may be associated with the extent of CAD and therefore ischemia. METHODS: Sixty-five consecutive patients with positive results on DSE and angiographically documented CAD were studied. Each patient underwent 12-lead electrocardiography and two-dimensional echocardiography at rest, during dobutamine infusion and continuously during recovery to assess the recovery time of ischemic myocardial regions. RESULTS: All patients had at least one ischemic region during DSE. Complete resolution of RWMAs occurred within 25 min in patients with multivessel CAD, within 20 min in those with two-vessel disease and within 15 min in those with single-vessel disease (p < 0.001). The greater the wall motion score index at peak stress, the longer the duration of RWMAs into the recovery phase (p < 0.01). RWMAs persisted long after normalization of each patient's symptoms, electrocardiographic (ECG) changes, heart rate and rate-pressure product during recovery. CONCLUSIONS: We demonstrated that normalization of left ventricular RWMAs occurs after resolution of symptoms and ECG changes during recovery. The time to recovery is related to the extent of CAD and myocardial ischemia as well as to the presence or absence of collateral circulation. These findings may represent stunned myocardium after brief period of ischemia.

Adult↗
PubMed2001

Beneficial effects of the Ca2+ sensitizer EMD 57033 in exercising pigs with infarction-induced chronic left ventricular dysfunction.

1. It is unknown how cardiac stimulation by Ca(2+) sensitization modulates the cardiovascular response to exercise when left ventricular (LV) function is chronically depressed following a myocardial infarction. We therefore investigated the effects of EMD 57033 at rest and during exercise and compared these to those of the mixed Ca(2+)-sensitizer/phosphodiesterase-III inhibitor pimobendan. 2. Pigs were chronically instrumented for measurement of cardiovascular performance. At the time of instrumentation, infarction was produced by coronary artery ligation (MI, n=12). Studies in MI were performed in the awake state, 2 - 3 weeks after infarction. 3. MI were characterized by a lower resting cardiac output (18%), stroke volume (30%) and LVdP/dt(max) (18%), and a doubling of LV end-diastolic pressure, compared to normal pigs (N, n=13). 4. In 11 resting MI, intravenous EMD 57033 (0.2 - 0.8 mg kg(-1) min(-1)) increased LVdP/dt(max) (57+/-5%) and stroke volume (26+/-6%) with no effect on heart rate, LV filling pressure, and myocardial O(2)-consumption, similar to N. 5. In MI, the effects of EMD 57033 (0.4 mg kg(-1) min(-1), IV) on stroke volume and LVdP/dt(max) were maintained during treadmill exercise up to 85% of maximal heart rate, while heart rate was lower compared to control exercise (all P<0.05). In contrast, the effects of EMD57033 gradually waned in N at increasing intensity of exercise. 6. Compared to N, the cardiostimulatory effects of pimobendan (20 microg kg(-1) min(-1), IV) were blunted in MI both at rest and during exercise compared to N. 7. In conclusion, the positive inotropic actions of the Ca(2+) sensitizer EMD 57033 are unmitigated in resting and exercising MI compared to N, while those of the mixed Ca(2+)-sensitizer/phosphodiesterase-III inhibitor pimobendan are blunted.

Animals↗
PubMed1999

Revascularization of residual viable myocardium improves left ventricular dysfunction in patients after myocardial infarction.

The symptoms and prognosis of patients after myocardial infarction are essentially influenced by left ventricular function. About 50% of infarct related segments contain partly viable myocardium. The aim of this study was to test the hypothesis that regional and global left ventricular function can be improved by revascularization of infarct related segments with residual myocardial viability. In 15 of 30 consecutive patients, residual viable myocardium was found in the affected segment within 2.2 +/- 1.6 months after AMI. Myocardial viability was estimated by exercise-redistribution-reinjection thallium scintigraphy (SPECT imaging). Rest and exercise radionuclide ventriculography was performed to measure regional and global left ventricular ejection fraction before and after revascularization of the infarct related artery. 10 +/- 3 months after revascularization we observed a significant increase in the regional left ventricular ejection fraction at rest (from 32 +/- 16% to 41 +/- 19%; p = 0.03), global left ventricular ejection fraction at rest (from 38 +/- 12% to 46 +/- 11%; p = 0.01), regional LV ejection fraction during exercise (from 34 +/- 16% to 46 +/- 20%; p = 0.01), and global left ventricular ejection fraction during exercise (from 38 +/- 14% to 49 +/- 14%; p = 0.02). The results show that after revascularization of infarct related segments with residual myocardial viability, the regional and global left ventricular ejection fraction may be significantly improved, both at rest and during exercise. Thus infarct related segments should be tested for residual viability. In its presence revascularization is recommended, as the left ventricular function may be markedly improved.

Aged↗
PubMed2004

Excessive tumor necrosis factor activation after infarction contributes to susceptibility of myocardial rupture and left ventricular dysfunction.

BACKGROUND: We investigated the potential contributions of tumor necrosis factor-alpha (TNF-alpha) on the incidence of acute myocardial rupture and subsequent chronic cardiac dysfunction after myocardial infarction (MI) in TNF knockout (TNF-/-) mice compared with C57/BL wild-type (WT) mice. METHODS AND RESULTS: Animals were randomized to left anterior descending ligation or sham operation and killed on days 3, 7, 14, and 28. We monitored cardiac rupture rate, cardiac function, inflammatory response, collagen degradation, and net collagen formation. We found the following: (1) within 1 week after MI, 53.3% (n=120) of WT mice died of cardiac rupture, in contrast to 2.5% (n=80) of TNF-/- mice; (2) inflammatory cell infiltration and cytokine expression were significantly higher in the infarct zone in WT than TNF-/- mice on day 3; (3) matrix metalloproteinase-9 and -2 activity in the infarcted myocardium was significantly higher in WT than in TNF-/- mice on day 3; (4) on day 28 after MI compared with sham, there was a significant decrease in LV developed pressure (74%) and +/-dP/dt(max) (68.3%/65.3%) in WT mice but a less significant decrease in +/-dP/dt(max) (25.8%/28.8%) in TNF-/- mice; (5) cardiac collagen volume fraction was lower in WT than in TNF-/- mice on days 3 and 7 but higher on day 28 compared with TNF-/- mice; and (6) a reduction in myocyte apoptosis in TNF-/- mice occurred on day 28 compared with WT mice. CONCLUSIONS: Elevated local TNF-alpha in the infarcted myocardium contributes to acute myocardial rupture and chronic left ventricle dysfunction by inducing exuberant local inflammatory response, matrix and collagen degradation, increased matrix metalloproteinase activity, and apoptosis.

Animals↗
PubMed1997

Left ventricular dysfunction: a clue to cognitive impairment in older patients with heart failure.

OBJECTIVES: Cognitive impairment has been reported in middle aged patients with end stage heart failure. This cross sectional study assessed the prevalence and determinants of cognitive dysfunction in older patients with mild to moderate heart failure. METHODS: 57 consecutive patients (mean age 76.7 years) with chronic heart failure underwent physical examination, blood chemistry, urinalysis, chest radiography ECG, Doppler echocardiography, and the mini mental state examination (MMSE), mental deterioration battery, depression scale of the Center for Epidemiological Studies (CES-D), Katz activities of daily living, and instrumental activities of daily living 24 hours before hospital discharge. RESULTS: MMSE scores <24 were found in 53% of participants. The MMSE score was associated with left ventricular ejection fraction according to a non-linear correlation, so that cognitive performance was significantly lower in subjects with left ventricular ejection fraction < or =30%. The same pattern of correlation was evidenced between left ventricular ejection fraction and both the attention sub-item of MMSE and the Raven test score. In a multivariate linear regression model, after adjusting for age, sex, and a series of clinical data and objective tests, both age (beta=-0.30; P=0.038) and the natural log of left ventricular ejection fraction (beta=0.58; P=0.001) were associated with the MMSE score. CONCLUSION: Cognitive impairment in older patients with chronic heart failure is common, and independently associated with lower left ventricular ejection fraction. Given the overwhelming incidence and prevalence of heart failure in older populations, early detection of cognitive impairment in these subjects with prompt, intensive treatment of left ventricular systolic dysfunction may prevent or delay a remarkable proportion of dementia in advanced age.

Aged↗
PubMed1995

3,5,3' Triiodo-L-thyronine pretreatment with cardioplegic arrest and chronic left ventricular dysfunction.

BACKGROUND: The active form of thyroid hormone, T3, may be an important determinant of left ventricular (LV) function after hypothermic cardioplegic arrest and rewarming, particularly in patients with preexisting LV dysfunction. Thus, the present project tested the hypothesis that T3 pretreatment will improve myocyte contractile performance after hypothermic cardioplegic arrest and rewarming in the setting of chronic LV dysfunction. METHODS: Control LV porcine myocytes (n = 160) and cardiomyopathic LV (rapid pacing for 3 weeks at 240 beats/min) myocytes (n = 100) were treated with or without 80 pmol/L T3. Myocytes then were maintained in normothermic conditions (2 hours at 37 degrees C in media) or exposed to hypothermic cardioplegic arrest ([K+], 24 mmol/L; 2 hours at 4 degrees C) with subsequent rewarming. RESULTS: After cardioplegic arrest and rewarming, T3 pretreatment increased myocyte velocity of shortening by 41% in control myocytes and by 35% in cardiomyopathic myocytes when compared to untreated myocytes. Furthermore, T3 pretreatment followed by beta-adrenergic receptor stimulation with isoproterenol (25 nmol/L) improved myocyte velocity of shortening by 24% in control myocytes and 90% in cardiomyopathic myocytes after hypothermic cardioplegic arrest and rewarming, as compared with untreated myocytes. CONCLUSIONS: In summary, this study provides evidence to suggest that preemptive treatment with T3 may improve LV pump function and beta-adrenergic responsiveness after hypothermic cardioplegic arrest and rewarming in patients with underlying LV dysfunction.

Animals↗
PubMed1994

The impact of left ventricular dysfunction on outcomes with the implantable defibrillator.

Implanted cardioverter defibrillators (ICDs) are very effective in the treatment of life-threatening ventricular arrhythmias. Among patients with severe left ventricular (LV) dysfunction, ICDs can defibrillate at energies similar to those in patients with well-preserved LV function; the perioperative mortality rate with transvenous systems is low, even in patients with a low ejection fraction (EF). In patients whose EF is < 30%, sudden death and total mortality rates are relatively low. However, at most only 50% of deaths in patients with low EFs are sudden, and life in these patients may be only slightly prolonged by successful defibrillator shocks. The true value of ICDs in these patients can be determined only by comparison with optimal medical therapy in randomized controlled studies. The Canadian Implantable Defibrillator Study randomly assigns patients with ventricular fibrillation or ventricular tachycardia to ICD or amiodarone. Current patient profiles show that most of these patients have poor LV function (mean EF, 33.6%), and most receive optimal medical therapy. Results of this and other studies will clarify the benefits from ICDs in these patients with severe heart disease.

Anti-Arrhythmia Agents↗
PubMed1999

Clinical significance of consecutive shocks in patients with left ventricular dysfunction treated with implantable cardioverter defibrillators.

The purpose of the present study was to determine the clinical significance of consecutive automatic shocks delivered by implantable cardioverter defibrillators (ICDs). Sixty-four patients who received ICDs at our institution between January 1990 and July 1997 were included in this study. There were 53 men and 11 women with a mean age of 50 +/- 14 years. During a follow-up period ranging between 0.2 and 73 months (mean 23 +/- 21 months), 17 patients received consecutive shocks (group A), 29 patients received single shocks (group B), and 18 patients received no ICD therapy (group C). Clinical characteristics, episodes of ICD therapy, and prognosis were compared among the three groups. There were no significant differences among the three groups with regard to clinical characteristics, time to first ICD therapy, number of antitachycardia pacing episodes, or frequency of inappropriate discharges. The mortality rate was higher in group A than in groups B and C (P = 0.0021). The sensitivity of consecutive shocks in predicting death was 70%, the specificity was 88%, and the predictive accuracy was 81% in patients with left ventricular ejection fractions < 35%. In summary, consecutive shocks are a clinically important event in patients with ICDs. Specifically, patients who receive consecutive shocks and have a depressed left ventricular function should be considered particularly high risk.

Defibrillators, Implantable↗
PubMed2006

Cardiac resynchronization therapy as an 'alternative' approach to a non-operable severe aortic stenosis with left ventricular dysfunction.

Severe symptomatic aortic stenosis (AS) is an indication for surgical replacement of the aortic valve in adults. Patients are often affected by comorbidities, and the surgical indication is sometimes problematic. Non-surgical techniques have been developed during the past few years, though their roles have not yet been established. Cardiac resynchronization therapy has been shown to be effective in selected patients, but no data yet exist on the role of this therapy in AS patients. The case is presented of a patient with non-operable severe symptomatic AS and cardiac dissynchrony who showed significant improvement following the implantation of a biventricular pacemaker.

Aged↗
PubMed1987

Cardiovascular time course after digoxin administration in left ventricular dysfunction after coronary artery bypass grafting.

Intravenous digoxin, 1 mg, was administered over 8 hours to 10 cardiac patients with left ventricular (LV) dysfunction after coronary artery bypass grafting. The cardiovascular effects of digoxin were monitored over 20 hours by indwelling pulmonary artery and radial artery lines and were compared with those of a control group of 10 patients who had normal postoperative LV function. Digoxin administration produced an increased cardiac index and mean arterial blood pressure within 2 hours. Within 4 hours after digoxin administration pulmonary artery wedge pressure in patients receiving digoxin was significantly lower than in control patients. At 16 hours there was a significant increase in both the LV stroke work and LV stroke work index in patients receiving digoxin vs control patients. Two patients receiving digoxin and 3 control patients had changes in cardiac rhythm during the study. Thus, digoxin can be safely administered to postoperative patients with LV dysfunction and is an acceptable inotropic agent.

Arrhythmias, Cardiac↗