Biomedical subjects
Publications and source records attributed to Roxy Senior.
Thirty-five patients underwent quantitative low-power myocardial contrast echocardiography to evaluate the severity of left anterior descending coronary artery stenosis. Coronary flow reserve and myocardial blood flow were able to accurately differentiate among angiographically derived grades of coronary stenosis.
BACKGROUND: No previous studies have compared myocardial contrast echocardiography (MCE) and single-photon emission computerized tomography (SPECT) for the detection of coronary artery disease (CAD) in patients with a medium likelihood of CAD. This study was developed to test the hypothesis that MCE is superior to SPECT for the detection of CAD. METHODS: Fifty-five patients with a medium probability of CAD and no previous myocardial infarction were recruited. Results of MCE and SPECT were compared to quantitative coronary arteriography, where CAD was defined as >50% stenosis. Each patient was examined for the anterior and posterior circulations. RESULTS: On a coronary circulation basis (n = 110), the sensitivity of MCE was significantly greater than that of SPECT for the detection of CAD (86% vs 43%, P <.0001). However, the specificities were similar (88% and 93%, P =.52). Both techniques were marginally more accurate in the anterior compared to the posterior circulation (88% vs 76%, P =.07 for MCE and 79% vs 63%, P =.19, for SPECT). On a patient basis (n = 55), MCE had a higher sensitivity than SPECT for the detection of CAD (83% vs 49%, P <.05). Although specificity tended to be higher for SPECT than MCE (92% vs 58%), it was not significant (P =.33). When CAD was defined as >40% coronary stenosis, the specificity of MCE increased to 83% without any change in sensitivity. CONCLUSION: In this preliminary study, MCE was found to be superior to SPECT during dipyridamole stress for the diagnosis of CAD in patients with a medium pretest probability of CAD. Larger studies are required to confirm these findings.
BACKGROUND: We hypothesized that imaging of regional myocardial function (RF) and perfusion (PER) will add incremental value for both diagnosis and short-term prognosis to routine demographic, clinical, and electrocardiographic findings in patients presenting to the emergency department (ED) with chest pain and without ST-segment elevation on the electrocardiogram. METHODS: We compared contrast echocardiography (CE) with gated single-photon emission computed tomography (SPECT) for this purpose. Both CE and SPECT readings included separate and composite assessments of both RF and PER. Adverse events in the first 48 hours after ED presentation included acute myocardial infarction, emergent revascularization, and cardiac-related death. RESULTS: Concordance between CE and SPECT was 77% (73% to 82%) for all territories, with a higher concordance for the anterior wall of 84% (78% to 89%). Of the 203 patients recruited for the study, 38 (19%) had a cardiac event within 48 hours of ED presentation: 21 had acute myocardial infarction, 16 underwent an urgent revascularization procedure, and 1 died. In multivariate logistic regression models, the number of abnormal segments on CE and SPECT were significant predictors (P <.05) of cardiac events. The composite scores on CE provided 17% incremental information (P =.009, n = 203) and gated SPECT provided 23.5% additional information (P =.020, n = 163) for predicting cardiac events compared with routine demographic, clinical, and electrocardiographic variables. RF and composite evaluation was superior on SPECT compared with CE, whereas PER alone was not. CONCLUSIONS: Cardiac imaging of RF and PER at the time of ED presentation offers substantially greater diagnostic and prognostic information for early cardiac events in patients presenting to the ED with chest pain and no ST elevation than does the routine demographic, clinical, and electrocardiographic assessment.
MCE is a reliable, bedside technique for assessment of a patient with acute coronary syndrome. It can be used to estimate the myocardial risk-area and infarct size and to establish peri-infarct viability. This information is critical in both management decision-making and in assigning prognosis in the setting of acute coronary syndromes.
Left ventricular (LV) hypertrophy (LVH) confers increased cardiovascular risk on patients with hypertension. Echocardiography using new hand-held devices might allow community-based cost-effective screening for LVH in a targeted hypertensive population. Thus, the aim of this study was to test the validity of hand-held ultrasound devices to screen for LVH in the community. Accordingly, 189 patients with hypertension attending a community-based heart failure screening program underwent echocardiography by both hand-held and standard devices by an experienced echocardiographer. LVH was defined as LV mass index >/=134 g.m(-2) for men and >/=110 g.m(-2) for women using the Devereux-modified American Society of Echocardiography cube equation. No significant differences were noted between the 2 devices in the measurement of LV wall thickness or LV mass index. Agreement for estimation of LVH between the 2 devices was 86% (kappa = 0.63). The sensitivity, specificity, and positive and negative predictive values of the hand-held device for predicting LVH were 72%, 91%, 73%, and 90%, respectively. Thus, hand-held echocardiography devices accurately assessed LVH and may be used for community-based screening for LVH in targeted patients with hypertension.
BACKGROUND: We investigated whether the extent of residual myocardial viability demonstrated by myocardial contrast echocardiography (MCE) predicts the degree of left ventricular (LV) remodelling after acute myocardial infarction as assessed by cardiovascular magnetic resonance. METHODS: Accordingly, 25 patients underwent MCE 5 to 7 days after acute myocardial infarction followed by cardiovascular magnetic resonance assessment of LV end-diastolic volume, LV end-systolic volume, and LV ejection fraction. A contrast perfusion index was calculated within the infarct-related territory. RESULTS: LV end-diastolic and end-systolic volumes were significantly smaller (138 +/- 38 vs 188 +/- 43 mL, P =.008, and 86 +/- 35 vs 119 +/- 49 mL, P =.01, respectively) and LV ejection fraction was significantly higher (52 +/- 5.4 vs 31.5 +/- 3.2%, P> =.02) in patients showing good myocardial viability (contrast perfusion index </= 1.5) compared with those without viability. MCE was the only multivariate predictor of LV volumes and LV ejection fraction at 2 weeks and 6 months. CONCLUSIONS: The extent of residual myocardial viability as demonstrated by MCE predicts the degree of LV remodelling after acute myocardial infarction.
AIMS: To investigate whether the vasoconstrictor isoprostane F2alpha-III (iPF2alpha-III), released during myocardial reperfusion, contributes to the low/no reflow phenomenon observed following acute myocardial infarction (AMI). METHODS AND RESULTS: Thirteen patients undergoing primary percutaneous coronary intervention (PCI) for AMI had iPF2alpha-III measured by high-performance liquid and gas chromatography-mass spectrometry. Isoprostane F2alpha-III concentrations were significantly higher following PCI than in controls (1.5+/-1.3 vs.16+/-0.06 nM, p < 0.001). Mean iPF2alpha-III concentration correlated positively with ST-segment resolution at 90 min (R = 0.62, p < 0.05). In the isolated murine heart: (a) coronary vasoconstriction occurred at, or above, iPF2alpha-III concentrations of 1 microM. From 1 to 10 microM, iPF2alpha-III induced dose-dependent vasoconstriction (p = 0.005) with reduction in coronary flows (f) of 57+/-5% and 31+/-4% (percentage baseline), respectively; (b) SQ29548 1 microM completely reversed the vasoconstrictive effects of iPF2alpha-III 10 microM; (c) SQ29548 1 microM infused during reperfusion following 30 min ischaemia had no effect on CF or infarct volume. CONCLUSION: Concentrations of iPF2alpha-III released into the venous circulation during reperfusion following AMI in humans are significantly lower than those required to diminish coronary flow in the murine heart; increased levels indicate successful reperfusion. Inhibition of iPF2alpha-III has no effect on coronary flow or infarct size in the murine heart, suggesting that iPF2alpha-III alone does not account for the low/no reflow phenomenon observed following AMI.
AIMS: To determine the prognostic value of a normal stress echocardiogram in the setting of a large district general non-university hospital in the United Kingdom. METHODS: Between January 1996 and December 1999, all patients who had undergone stress echocardiography were identified and those with normal results were studied. Normal stress echocardiograms were found in 252 patients, 19 of whom were lost to follow-up. Deaths and nonfatal myocardial infarctions were considered hard cardiac events and data was collected in the remaining 233 patients. RESULTS: Among the 233 patients, the pre-test probability of coronary artery disease was low in 68 (27.9%) and intermediate or high in 168 (72.1%). During a follow-up period of mean (SD) 2.7 (1.1) years, death occurred in 4 patients of which 3 were consequent to acute myocardial infarctions and 1 was unexplained. One patient sustained a nonfatal infarction. Thus, the annualized mortality and hard event rates were 0.6% per patient/year and 0.8% per patient/year, respectively. CONCLUSIONS: A normal stress echocardiogram portends an excellent prognosis, even in a cohort with a high proportion of patients having intermediate or high pre-test probability of coronary artery disease.
BACKGROUND: Experimental evidence suggests that although vasodilator stress agents consistently induce regional flow disparity between stenosed and normal coronary vascular beds, the occurrence of functional myocardial ischemia is infrequent, especially in mild-to-moderate coronary artery stenosis. Thus, it is hypothesized that dipyridamole infusion, even at high doses, will result in a disproportionately higher frequency of perfusion defects compared to regional wall thickening abnormalities. METHODS: We performed simultaneous high-dose (0.84 mg/kg) dipyridamole stress echocardiography (Echo) and Tc-99m sestamibi SPECT (MIBI, methoxyisobutyl isonitrile) in 46 patients with coronary artery diameter stenosis >50% and < o =90% in one or two epicardial coronary arteries, and no previous myocardial infarction. RESULTS: Of a total of 828 segments, MIBI showed 97 reversible defects while Echo showed only 23 reversible wall thickening abnormalities. Of the 97 segments with reversible MIBI defects, only 13 (13%) showed simultaneous reversible wall thickening abnormalities during dipyridamole infusion. There were 24 patients with MIBI defects, of whom 10 (41%) showed a corresponding wall thickening abnormality. The sensitivity of MIBI and Echo for the detection of coronary artery disease was 52% and 21%, respectively (P = 0.001). CONCLUSION: This suggests that vasodilator stress is not optimally suited for use with techniques that use regional wall thickening abnormality as a marker of ischemia for the diagnosis of coronary artery disease.
Microvascular perfusion is a prerequisite for ensuring viability early after acute myocardial infarction (AMI). For adequate assessment of myocardial perfusion, both myocardial blood volume and velocity need to be evaluated. Due to its high frame rate, low-power continuous myocardial contrast echocardiography (MCE) can rapidly assess these parameters of myocardial perfusion. We hypothesized that the technique can accurately differentiate necrotic from viable myocardium after reperfusion therapy in AMI. Accordingly, 50 patients underwent low-power continuous MCE using intravenous Optison (Amersham Health, Amersham, Middlesex, United Kingdom) 7 to 10 days after AMI. Myocardial perfusion (contrast opacification assessed over 15 cardiac cycles after the destruction of microbubbles with high energy pulses) and wall thickening were assessed at baseline. Regional and global left ventricular (LV) function was reassessed after 12 weeks. Out of the 297 dysfunctional segments, MCE detected no contrast enhancement during 15 cardiac cycles in 172 segments, of which 160 (93%) failed to show improvement. MCE demonstrated contrast opacification during 15 cardiac cycles in 77 segments, of which 65 (84%) showed recovery of function. The greater the extent and intensity of contrast opacification, the better the LV function at 3 months (p <0.001, r = -0.91). Almost all patients (94%) with <20% perfusion in dysfunctional myocardium (assessing various cut-offs) failed to demonstrate an improvement in LV function. MCE and peak creatine kinase proved to be independent predictors of functional recovery (p <0.001). In conclusion, low-power continuous MCE is an accurate and rapid bedside technique to identify microvascular perfusion after AMI. This technique may be utilized to reliably predict late recovery of function in dysfunctional myocardium after AMI.
We hypothesized that the presence of microvascular integrity, detected by myocardial contrast echocardiography (MCE) in dobutamine nonresponsive segments, may enhance identification of recovery of function, which is a surrogate marker of myocardial viability. Accordingly, 96 patients underwent dobutamine echocardiography (DE) and intravenous MCE on the same day, 4.6 +/- 1.5 days after acute myocardial infarction (AMI). Recovery of function of akinetic segments was assessed at 3 months after AMI. Of 387 akinetic segments, 102 (26%) recovered function during follow-up. Sensitivities and specificities of MCE, DE, and the combination of DE and MCE in dobutamine nonresponsive segments were 58%, 59%, and 79%, respectively (p <0.001, compared with MCE and DE) and 76%, 84%, and 69%, respectively (p <0.05 compared with DE) for predicting recovery of function. In anterior AMI, the positive and negative predictive values of MCE, DE, and the combination of DE and MCE were 47% and 88%, 57% and 89%, and 49% and 95%, respectively. Multivariate analysis using clinical characteristics, electrocardiography, biochemical factors, MCE, and DE showed that the combination of DE and MCE in dobutamine nonresponsive segments (p <0.00001) and Q-wave AMI (p = 0.002) were the only independent predictors of recovery of function. Thus, for optimum prediction of recovery of function after AMI, a combination of DE and MCE in dobutamine nonresponsive segments may be utilized.
We report the case of a 63-year-old woman who presented to her local emergency department unresponsive and in a state of cardiogenic shock 4 hours after the sudden onset of a severe headache. Her electrocardiogram revealed nonprogressive 1-mm S-T elevation in leads V(5) to V(6) and a prolonged QTc. A transthoracic echocardiogram performed at the time of her resuscitation revealed regional wall-motion abnormalities not consistent with any known coronary artery territory but consistent with a diagnosis of acute subarachnoid hemorrhage. This diagnosis was subsequently confirmed on computed tomography brain imaging. Although subarachnoid hemorrhage is known to be associated with cardiopulmonary dysfunction, and electrocardiogram and echocardiogram abnormalities, the diagnosis of subarachnoid hemorrhage suspected by echocardiography before brain imaging has not previously been described.
With or without contrast, echocardiographic evaluation of left ventricular (LV) function is qualitative, subjective, and experience dependent, because it is mostly based on visual interpretation of gray-scale 2-dimensional images or, at best, relies on tedious and time-consuming manual tracing of the endocardial boundaries. Adequate endocardial visualization is essential for accurate interpretation of regional wall thickening abnormalities, which constitute the diagnostic hallmark of coronary artery disease, and for reproducible assessment of LV ejection fraction. Studies performed in the last decade have estimated the number of patients with suboptimal endocardial delineation by fundamental imaging at 30%. These studies have highlighted the problem of variable image quality as a major limitation of transthoracic echocardiography because failure to adequately visualize a segment, either at rest or during stress, may compromise the ability of this technique to identify areas of dysfunctional myocardium. Several remedies based on different technologic and methodologic approaches have been tested over the years with variable success. In this review we discuss the most recent techniques that have had a positive impact on endocardial visualization, as well as the potential benefits of these approaches.
AIM: To delineate the natural history of left ventricular remodelling following large anterior myocardial infarction (MI), in the era of aggressive medical therapy. METHODS: Seventeen selected patients underwent cardiovascular magnetic resonance (CMR) at 2 weeks and 1, 3, 6 and 12 months post infarction. RESULTS: There was a significant increase in left ventricular (LV) end-diastolic volume index (EDVI) and LV ESVI from 2 weeks to 1 month (P<0.05) but no significant change thereafter. The LV ejection fraction (EF) decreased from 2 weeks to 1 month (P<0.05) and then increased over the year (P=0.02). Throughout the study period the sphericity index increased. There was a significant and progressive decrease in LV mass index over the year, which was associated with a decrease in wall thickness at both the infarct and non-infarct sites. Independent predictors of an early increase in LVESVI were increasing age, increasing CK-MB and not receiving treatment with a statin. CONCLUSION: This study delineates the natural history of left ventricular remodelling in the modern medical era in those patients who have suffered a large anterior MI. Classical remodelling occurred up to 1 month, but thereafter was attenuated. These findings would suggest that remodelling is not as prevalent in the modern era, and that combined medical management with thrombolysis, ACEi, beta-blockers and statins may strongly influence the development of this remodelling.
BACKGROUND: Patients with pathological left ventricular hypertrophy have depressed midwall systolic shortening in spite of normal indices of left ventricular chamber function and a reduced midwall function has been observed to be an independent predictor of cardiovascular risk. Whether midwall shortening is depressed in physiological hypertrophy is unknown. METHODS: Forty-two subjects, 27 athletes and 15 age- and sex-matched normal control subjects (group 1) were studied. The athletes were divided into those with eccentric hypertrophy (group 2) and those with concentric hypertrophy (group 3). Systolic left ventricular function was assessed at the midwall and endocardium using two-dimensional echocardiography in all subjects. RESULTS: Left ventricular mass index was significantly greater in both athletic groups than in controls (group 1, 101+/-5.8 g/m(2), group 2, 141+/-11.1*, group 3, 155+/-5.8*; *P<0.01 compared with group 1). Left ventricular systolic function assessed at the endocardium was similar among all three groups (ejection fraction: group 1, 66.2+/-2.38, group 2, 66.8+/-1.44, group 3, 63.7+/-1.66%; endocardial fractional shortening: group 1, 37.1+/-1.71, group 2, 37.6+/-1.13, group 3, 35.1+/-1.25%). However, fractional shortening at the midwall was reduced in the concentric hypertrophy athletes compared with the other two groups (midwall fractional shortening: group 1, 21.9+/-1.1, group 2, 21.9+/-0.86, group 3, 18.4+/-0.96*%; P<0.05 compared with groups 1 and 2). CONCLUSION: Subjects with physiological concentric hypertrophy have depressed midwall fractional shortening. This suggests that the observed discrepancy between midwall and endocardial shortening in patients with left ventricular hypertrophy is likely to be a function of the geometry and not necessarily a reflection of pathology within the myocardium.
BACKGROUND: Clinical factors, electrocardiography, and cardiac troponins provide a satisfactory, although not ideal, means for risk-stratifying patients with non-ST-segment elevation acute chest pain. Tissue harmonic echocardiography enables improved assessment of wall motion abnormalities compared with fundamental echocardiography and may be a useful adjunct for the detection of myocardial ischemia and infarction. We aimed to determine the value of tissue harmonic echocardiography in relation to electrocardiographic and biochemical factors for risk stratification of these patients. RESULTS: Eighty patients with non-ST-segment elevation chest pain were studied using tissue harmonic echocardiography and troponin-T and -I. Fifty-five (69%) patients had abnormal electrocardiograms and 47 (59%) patients had abnormal echocardiograms. Thirteen patients (17%) had elevated troponin-T levels and 17 (21%) had elevated levels of troponin-I. Twelve patients (15%) had a myocardial infarction as the presenting event and, of the remaining 68 patients, 24 sustained an adverse cardiac event during the follow-up period (3 cardiac deaths, 4 nonfatal myocardial infarctions, 17 revascularization procedures). Troponin-T (98%), troponin-I (97%), and echocardiography (97%) all had similar negative predictive values for myocardial infarction as the presenting event, but troponin-T was the only independent predictor of this endpoint (relative risk 230, 95% CI 22-2427). An abnormal echocardiogram was the only independent predictor of subsequent events. The independent predictors of all events were age, troponin-T, and echocardiography. CONCLUSION: Tissue harmonic echocardiography provides independent information for risk stratification of patients with non-ST-segment elevation acute chest pain.
Despite the recent introduction of tissue harmonic imaging in echocardiography, in 10%-15% of patients endocardial borders of the left ventricle are poorly defined. This may lead to erroneous assessment of regional and global left ventricular (LV) function or further diagnostic imaging with another modality leading to increased cost to the healthcare system. The recent development of second generation contrast echocardiography agents such as SonoVue has resulted in several studies showing the value of these agents to outline endocardium clearly, thereby improving assessment of LV function. The use of these contrast agents has also opened the possibility of automated and qualitative LV function assessment, resulting in more accurate and reproducible assessment. Other major clinical uses of these contrast agents are evaluation of LV masses such as thrombus and tumors, and better definition of LV structure such as delineating LV aneurysm, pseudoaneurysm; and noncompaction of LV and apical cardiomyopathy. Thus, it is clear that contrast-enhanced LV assessment at rest will play an important role in echocardiography.
The endocardial border of the left ventricle is incompletely identified in at least 30% of patients at rest or during stress echocardiography during fundamental imaging. This may lead to inaccurate assessment of regional and global left ventricular function or may lead to further diagnostic imaging with another modality resulting in a higher cost of healthcare. The recent development of second generation ultrasound contrast agents has resulted in improved detection of endocardial border at rest and during stress fundamental echocardiography. This has been consistently shown in various clinical trials involving 702 patients using a new contrast agent, SonoVuetrade mark. Other studies with contrast agents have also shown improved accuracy for determining left ventricular ejection fraction and volumes. Although unenhanced tissue harmonic imaging itself improved the assessment of left ventricular function, contrast enhanced harmonic imaging has recently been shown to be more accurate; however, larger clinical studies are required to establish the value of harmonic contrast imaging for the assessment of left ventricular function.