Effect of cardiac resynchronization therapy on regional left ventricular function: a speckle tracking strain analysis.

AIMS: The mechanisms associated with cardiac resynchronization therapy (CRT) benefits have been elucidated in part, however little is known about the effects of biventricular pacing (BVP) on regional myocardial contractility. METHODS AND RESULTS: Twenty patients with conventional CRT criteria were studied before and after device implantation. Speckle tracking strain analysis was performed from standard bidimensional acquisitions during different pacing configurations. Longitudinal and transverse strains were measured for the six basal left ventricular (LV) segments. Acute CRT improved LV end-diastolic and end-systolic volumes without significantly modifying LV ejection fraction. Moreover, CRT produced significant changes in regional strain. When compared with spontaneous rhythm, simultaneous BVP caused a significant increase in longitudinal septal strain (-4.8 vs. -7.3%, P = 0.003) and a significant decrease in longitudinal lateral strain (-8.2 vs. -5.9%, P = 0.03). Simultaneous BVP also induced a significant decrease in transverse lateral strain from 17.9 to 10.9% (P = 0.004). CONCLUSION: In this acute echocardiographic study, BVP decreased lateral wall deformation while improving septal wall contraction, thus potentially improving LV contractile pattern.

Assessment of a right ventricular metastasis using contrast echocardiography perfusion imaging.

Cardiac metastases of thyroid carcinomas are rarely diagnosed ante mortem and infrequently reported in the literature. A 68-year-old man with known papillary thyroid carcinoma presented to the hospital with progressive shortness of breath. A transthoracic echocardiogram revealed a right ventricular mass. Contrast echocardiography perfusion imaging was used to evaluate the vascularity of the mass.

Echocardiographic evaluation of cardiac dyssynchrony.

First described a decade ago, cardiac resynchronization therapy (CRT) has recently become a proven therapeutic strategy for refractory heart failure. Large clinical trials have shown a reduction in both morbidity and mortality in patients treated with CRT. Initial patient selection has relied mainly on electrocardiographic criteria, which allows identification of only 70% of responders. Accordingly, echocardiographic criteria were developed to identify mechanical dyssynchrony in an effort to improve patient selection. Multiple echocardiographic criteria have since been proposed, with no consensus as to which parameter better predicts CRT response. Although comparison studies using different criteria are underway, current evaluation of dyssynchrony should probably use an integrated multiparameter approach. The objective of the present article was to review the role of echocardiography in the evaluation of cardiac dyssynchrony in clinical practice.

Contrast echocardiography in Canada: Canadian Cardiovascular Society/Canadian Society of Echocardiography position paper.

As an adjunct to transthoracic, transesophageal and stress echocardiography, contrast echocardiography (CE) improves the diagnostic accuracy of technically suboptimal studies when used in conjunction with harmonic imaging. Intravenous ultrasound contrast agents are indicated for left ventricular (LV) opacification and improvement of LV endocardial border delineation in patients with suboptimal acoustic windows. Demonstrated benefits of CE include improvement in the accuracy of LV measurements, regional wall motion assessment, evaluation of noncompaction cardiomyopathy, thrombus detection, Doppler signal enhancement and conjunctive use with stress echocardiography. Studies have shown the value of CE in the assessment and quantification of myocardial perfusion, and recent clinical trials have suggested a role for contrast perfusion imaging in the stratification of patients with suspected coronary artery disease. While it adds some time and cost to the echocardiographic study, CE frequently obviates the need for additional specialized, expensive and less accessible cardiac investigations, and allows for prompt and optimal subsequent patient management. Despite its proven advantages, CE is presently underused in Canada, and this situation will, unfortunately, not improve until several barriers to its use are overcome. Resolving these important hurdles is vital to the future of CE and to its eventual implementation into clinical practice of promising contrast-based diagnostic and therapeutic applications, including the assessment of perfusion by myocardial CE.

Prescription patterns of pharmacological agents for left ventricular systolic dysfunction among hemodialysis patients.

BACKGROUND: Recommendations for the management of left ventricular (LV) systolic dysfunction in the general population and patients with end-stage renal disease (ESRD) include the use of angiotensin-converting enzyme (ACE) inhibitors and beta-blockers. Limited data from the literature suggest that these pharmacological agents may be underused in patients with ESRD. The goal of this study is to describe the use of these medications and investigate barriers to their use in dialysis patients. METHODS: We prospectively studied 420 hemodialysis patients. Diagnosis of systolic dysfunction was based on echocardiogram results. Use of cardiac medication was recorded for all patients with systolic dysfunction, and a questionnaire was administered to nephrologists to determine the basis for decisions concerning ACE-inhibitors and beta-blockers use/nonuse. RESULTS: Forty-seven patients (11%) were found to have an LV ejection fraction of 40% or less. Of those, 72% were administered a beta-blocker and 36% were administered an ACE inhibitor. Only 12 patients (25.5%) were administered a combination of beta-blocker and ACE inhibitor. Reasons indicated by nephrologists for not prescribing these medications were "concern about adverse reactions (eg, hypotension, hyperkalemia)" in 88% of cases, "adequate control of symptoms with ultrafiltration" in 38%, "unproven benefit" in 25%, and "unfavorable risk-benefit ratio" in 17%. Medication costs and concern about patient compliance were not identified as significant concerns by physicians. CONCLUSION: Only 25.5% of patients with ESRD with LV systolic dysfunction receive appropriate treatment. Concern regarding adverse reactions was the most frequent reason indicated by nephrologists for not prescribing ACE inhibitors and beta-blockers.

Intensity of lipid lowering with statins and brachial artery vascular endothelium reactivity after acute coronary syndromes (from the BRAVER trial).

The time course and differential effects of statin regimens on endothelial function after acute coronary syndromes (ACSs) are unknown and could contribute to the superiority of a more intense strategy. A subset of subjects who were enrolled in the PROVE IT-TIMI 22 trial (n = 50) underwent evaluation of vascular reactivity by high-resolution brachial ultrasound. Endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent sublingual nitroglycerin-mediated dilation (NMD) were measured at baseline and at 48 hours, 1 month, and 4 months after the initiation of 40 mg of pravastatin (n = 26) or 80 mg of atorvastatin (n = 24). After 4 months, low-density lipoprotein cholesterol was decreased by 32% in the atorvastatin group but was not different from baseline after ACS in the pravastatin group. C-reactive protein decreased similarly in the 2 groups. Brachial artery diameters at rest were similar in the 2 groups and at each time point of the trial. FMD and NMD increased significantly after 4 months by 27% and 24%, respectively (p <0.05), with no difference between groups. There was no correlation between the change in FMD and the change in lipids or C-reactive protein. In subjects who had received previous statin therapy (n = 15), there was no significant variation in FMD (p = 0.140) and NMD (p = 0.129). In conclusion, initiation of statin therapy soon after ACS is associated with improvements in endothelium-dependent and independent vascular reactivities after 4 months.

Left ventricular ejection fraction assessment by non-cardiologists from transverse views using a simplified wall motion score index.

For the non-cardiologist emergency physician and intensivist, performing an accurate estimation of left ventricular ejection fraction (LVEF) is essential for the management of critically ill patients, such as patients presenting with shock, severe respiratory distress or chest pain. Our objective was to develop a semi-quantitative method to improve visual LVEF evaluation. A group of 12 sets of transthoracic echocardiograms with LVEF in the range of 18-64% were interpreted by 17 experienced observers (PRO) and 103 untrained observers or novices (NOV), without previous training in echocardiography. They were asked to assess LVEF by two different methods: i) visual estimation (VIS) by analysing the three classical left ventricle (LV) short-axis views (basal, midventricular and apical short-axis LV section) and ii) semi-quantitative evaluation (base, mid and apex (BMA)) of the same three short-axis views. The results for each of these two methods for both groups (PRO and NOV) were compared with LVEF obtained by radionuclide angiography. The semi-quantitative method (BMA) improved estimation of LVEF by PRO for moderate LV dysfunction (LVEF 30-49%) and normal LVEF. The visual estimate was better for lower LVEF (<30%). In the NOV group, the semi-quantitative method was better than than the visual one in the normal group and in half of the subjects in the moderate LV dysfunction (LVEF 30-49%) group. The visual estimate was better for the lower LVEF (ejection fraction <30%) group. In conclusion, semi-quantitative evaluation of LVEF gives an overall better assessment than VIS for PRO and untrained observers.

Two-dimensional echocardiography estimation of right ventricular ejection fraction by wall motion score index.

BACKGROUND: Radionuclide angiography (RNA) and echocardiography (biplane Simpson method) are the most accepted methods for right ventricular ejection fraction (RVEF) evaluation. The authors tried to determine a new method to measure RVEF based on wall motion score index (WMSI). OBJECTIVES: One hundred forty-one patients with RV dysfunction had transthoracic echocardiography (TTE) evaluation of the right ventricle. In a first group of 54 patients, a correlation between RVEF using the biplane Simpson method (four chamber and two chamber [4C+2C]) and RV-WMSI was established from a polar map using an eight-segment model to find a regression equation. With the second group of 51 subsequent patients, this equation (RVEF=73.07-20.7 x WMSI), comparing the RVEF-WMSI with the biplane Simpson RVEF (4C+2C), was validated. In a third group of 36 consecutive patients with abnormal RV contractility, the RVEF was calculated by RNA and this RVEF was correlated to the RV-WMSI. RESULTS: The first group of 54 patients had a correlation coefficient of 0.84 between WMSI and RVEF (biplane Simpson method). The results from the second group of 51 patients with RVEF derived from the estimated regression equation correlated well with the biplane Simpson RVEF (r=0.84). The correlation coefficient for these two groups taken together (105 patients), that is, between WMSI and RVEF (biplane Simpson method), was 0.92. The third group of 36 patients with RNA-EF displayed a correlation coefficient of 0.83 with RV-WMSI. CONCLUSION: This new semiquantitative method for estimating RVEF from RV-WMSI is easy to use in routine TTE and shows an excellent correlation with the biplane Simpson method and RNA.

A new tool for estimating left ventricular ejection fraction derived from wall motion score index.

BACKGROUND: Radionuclide angiography (RNA) and echocardiography (biplane Simpson method) are the most accepted techniques for left ventricular ejection fraction (LVEF) assessment. A new method to evaluate LVEF based on the regional wall motion assessment of the LV was attempted. OBJECTIVE: To develop a simple method for LVEF estimation using wall motion score index (WMSI) with transthoracic echocardiography (TTE). METHODS: Two hundred and forty-three patients with abnormal LV contractility had TTE and RNA performed less than three days apart. The WMSI was calculated in all patients using the 16-segment model as proposed by the American Society of Echocardiography. For the first 150 patients, a correlation between LV WMSI and RNA EF was established to create a regression equation. This regression equation (RNA LVEF=92.8-25.8xWMSI) was used on 93 consecutive patients to compare this equation with RNA EF. From the total cohort (243 patients), three subgroups were studied specifically: atrial fibrillation (AF) (n=50 patients), dyskinesia (DK) (n=40 patients) and aneurysm (AN) (n=42 patients). RESULTS: Correlation between RNA EF and WMSI in the first 150 patients was r=0.82. In the second group of 93 consecutive patients, WMSI EF derived from the estimated regression equation correlated well with RNA EF (r=0.86). Correlation remained high in the three subgroups: AF (r=0.87), DK (r=0.87) and AN (r=0.80). In the 111 patients without DK, AN or AF correlation between RNA and the studied method was even higher (r=0.91). In a random subgroup of 54 patients, RNA was compared with the biplane Simpson method (49 of 54 patients, r=0.82). In the same subgroup of 54 patients, the score was modified to allow for mild hypokinesia (score=1.5) and severe hypokinesia (score=2.5) (54 of 54 patients, r=0.83). CONCLUSION: LVEF assessment by this new simple mathematical model using the WMSI is feasible and easy to use during routine TTE. It has excellent correlation with other methods such as biplane Simpson and RNA.

Ventricular septal rupture and right ventricular free wall dissection after inferior myocardial infarction: a case report and review of the literature.

Ventricular septal rupture (VSR) with dissection of the right ventricular free wall is an extremely rare complication after inferior myocardial infarction. Mortality is 100% without surgical treatment. The optimal surgical strategy remains unclear because of the limited number of cases, but repair of VSR alone might be equally effective as repair of VSR and right ventricular free wall reconstruction. Transesophageal echocardiography is an important adjunct to transthoracic echocardiography to establish the diagnosis.

Comparison of electrocardiographic recordings in open-chest and closed-chest swine models.

The aim of our study was to compare the electrocardiographic recordings in an experimental open-chest swine model before and after left-sided thoracotomy to detect any surgery-induced fluctuations that might interfere with subsequent experimental interventions. We obtained electrocardiograms from 8 deeply anesthetized domestic swine and compared the respective ST-segment potentials obtained after vascular surgery and after left-sided thoracotomy and dissection of the left anterior descending coronary artery. Compared with baseline recordings, no significant ST-segment deviation on any of the electrocardiographic leads occurred after vascular surgery. However, statistically significant ST-segment depression was observed after thoracotomy. Invasive surgical procedures in open-chest swine models may lead to morphologic changes in the ST segment. The physiologic mechanism of these changes is not fully understood.

The Epworth Sleepiness Scale: self-administration versus administration by the physician, and validation of a French version.

BACKGROUND/OBJECTIVES: The Epworth Sleepiness Scale (ESS) measures sleepiness and is used for, among others, patients with obstructive sleep apnea (OSA). The questionnaire is usually self-administered, but may be physician administered. The aim was to compare the two methods of administration and to validate a French version. METHODS: Consecutive patients presenting to the sleep clinic at a tertiary care centre completed a self-administered questionnaire containing the ESS. During the medical interview the same day, one of three pulmonologists who specialized in sleep medicine administered the ESS. Correlations with the apnea-hypopnea index and mean sleep latencies were used to assess construct validity, while results of previous self-administered ESS questionnnaires in untreated and recently treated OSA patients were used to test reproducibility and longitudinal construct validity, respectively. RESULTS: In OSA patients, the ESS weakly correlated with the apnea-hypopnea index (r=0.224; P=0.05; n=120) and negatively with mean sleep latency. For untreated patients (test-retest), the mean (+/- SD) average score was unchanged (10.3+/-6.0 to 10.8+/-6.5; P=0.35; n=56) after a median of seven months. With continuous positive airway pressure use, the mean score decreased from 12.4+/-6.8 to 7.6+/-5.0 after 40.2 months (P<0.0001; n=68). For all subjects, the ESS score obtained by the physician was less than that of the self-administered result (9.4+/-5.9 versus 8.5+/-5.8; P<0.0001 [paired t test]; n=188). CONCLUSIONS: In a sleep clinic population, the French version of the ESS performed similarly to the English version. However, the systematic underscoring during physician administration may be important to consider in the research setting if questionnaire administration methods are not consistent.

Progressive epicardial coronary blood flow reduction fails to produce ST-segment depression at normal heart rates.

ST-segment depression is commonly seen in patients with acute coronary syndromes. Most authors have attributed it to transient reductions in coronary blood flow due to nonocclusive thrombus formation on a disrupted atherosclerotic plaque and dynamic focal vasospasm at the site of coronary artery stenosis. However, ST-segment depression was never reproduced in classic animal models of coronary stenosis without the presence of tachycardia. We hypothesized that ST-segment depression occurring during acute coronary syndromes is not entirely explained by changes in epicardial coronary artery resistance and thus evaluated the effect of a slow, progressive epicardial coronary artery occlusion on the ECG and regional myocardial blood flow in anesthetized pigs. Slow, progressive occlusion over 72 min (SD 27) of the left anterior descending coronary artery in 20 anesthetized pigs led to a 90% decrease in coronary blood flow and the development of ST-segment elevation associated with homogeneous and transmural myocardial blood flow reductions, confirmed by microspheres and myocardial contrast echocardiography. ST-segment depression was not observed in any ECG lead before the development of ST-segment elevation. At normal heart rates, progressive epicardial stenosis of a coronary artery results in myocardial ischemia associated with homogeneous, transmural reduction in regional myocardial blood flow and ST-segment elevation, without preceding ST-segment depression. Thus, in coronary syndromes with ST-segment depression and predominant subendocardial ischemia, factors other than mere increases in epicardial coronary resistance must be invoked to explain the heterogeneous parietal distribution of flow and associated ECG changes.

Absence of clinically significant increase in pulmonary artery pressure after intravenous perflutren injection for myocardial perfusion imaging in pigs.

OBJECTIVE: We sought to evaluate the impact of a continuous intravenous infusion of perflutren on systemic pulmonary artery pressures at clinically relevant doses for myocardial perfusion imaging in pigs. METHODS: Five anesthetized, ventilated, open-chest pigs were administered perflutren intravenously at a rate of 0.0364 mL/kg/min over approximately 5 minutes. RESULTS: Optimal, sustained myocardial opacification was achieved in all animals. Perflutren produced transient, reversible increases in pulmonary artery pressures versus baseline: 10.6% (3.0 +/- 1.4 mm Hg; 95% confidence interval 1.7-4.2; P < .01) for systolic, 15.2% (2.5 +/- 1.4 mm Hg; 95% confidence interval 1.3-3.7; P < .05) for diastolic, and 11.6% (2.6 +/- 1.1 mm Hg; 95% confidence interval 1.68-3.65; P < .01) for mean pressures. Heart rate and systemic arterial pressures displayed nonsignificant increases during perflutren infusion compared with baseline. CONCLUSION: A continuous intravenous infusion of perflutren at a rate achieving optimal, sustained myocardial perfusion imaging in pigs induces a mild, transient, not clinically significant increase in pulmonary artery pressures without affecting heart rate or systemic arterial pressures.