Dipyridamole-echocardiography test as a clue for assessing the organic 'ceiling' of individual coronary reserve

Twenty-four patients with a history of effort angina, a positiveexercise stress test (EST) and coronary artery disease wereenrolled in the study; 12 patientshada positive dipyridamole-echocardiographytest (DET) and 12 had a negative DET. Each patient performeda total of 4 ESTs in the absence of therapy on two successivedays; for each test the rate-pressure product (RPP), an establishedindex of my ocardial oxygen demand, was measured at the onsetof ischaemia (ST depression >0–15mV) or at the peakof maximal exercise (if a repeated EST was negative). Taking into account the lowest of the 4 RPP values ( x 1/100)in each patient, there was no significant difference betweenDET-negatives and DET-positives (185.2±49.3 vs 157.4±32.4).Conversely, when considering the highest of the 4 RPP valuesin each patient, there was a significant difference betweenDET-negatives and DET-positives (280.3 ± 63.9 vs 183.3± 37.0; p < 0.01). Thus, DET may provide a clinically useful tool for assessingin the individual the organic ’ceiling‘ of coronaryreserve, by eliminating the variability in coronary tone, whichmay affect EST reproducibility and the correct evaluation ofthe impairment of organic coronary reserve.     

Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dipyridamole echocardiography

Dipyridamole echocardiography test (DET) has gained acceptancedue to its safety, feasibility, diagnostic accuracy and prognosticpower. The main limitation of the test is a less than idealsensitivity in some patient subsets, such as those with limitedcoronary artery disease. Atropine with dipyridamole might theoreticallycombine to become a synergistic ischaemic stress test, by increasingmyocardial oxygen demand through chronotropic stress and byreducing flow supply through a shortening of the diastolic intervalunder maximal coronary vasodilation. The aim of this study wasto assess the effects of the addition of atropine to DET. Threehundred and twenty-one patients (age=58±9 years), referredfor testing in the echo lab, were initially studied by DET.Of these, 151 were stopped during or within the 2 min followingdipyridamole infusion because of achievement of a predeterminedend-point: obvious echocardiographic positivity (n = 137), severechest pain (n = 3), diagnostic ST segment changes (n = 7) orlimited side effects (n = 4). In another three cases, atropinewas not given due to a history of glaucoma or severe prostatichypertrophy. In the remaining 167 patients with a negative DETtest, atropine (0.25 mg intravenously, repeated every min upto a maximum of 1 mg, if necessary) was added, starting 3 minafter the end of the dipyridamole infusion. The dipyridamole-atropineecho test (DETA) was positive in 32 and negative in 135 patients,and no major side effects occurred in any patient. The peakheart rate was significantly higher during DETA than with DETalone (108±16 vs 86±14 beats . min^–1; P<0.0001).In the subset of 178 patients who were studied while not takingantianginal therapy, who had no prior myocardial infarctionor revascularization procedure and who underwent coronary catheterization,independently of the test results, coronary angiography showednormal coronary arteries in 48 patients and significant coronaryartery disease (CAD) ( 50% luminal reduction in at least onemajor coronary vessel by quantitative coronary arteriography)in 130 patients—with single-, double- and triple-vesseldisease in 56, 47 and 27 patients, respectively. The sensitivitywas 96/130 for DET and 110/130 for DETA (72 vs 85%, P<0.01)while the specflcity was 96% and 92% (P=ns), respectively. Theaddition of atropine to dipyridamole, which causes further chronotropicstress to the myocardium already challenged by flow maldistribution,is well tolerated and safe, and increases the sensitivity ofthe test for the detection of coronary artery disease with noloss in specificity.     

Transthoracic Sensor for Noninvasive Assessment of Left Ventricular Contractility: Validation in A Minipig Model of Chronic Heart Failure

Background: Invasively measured left ventricular (LV) dP/dt is the accepted standard for measuring acute and chronic directional changes in LV contractility. Recently, we developed a noninvasive force sensor based on an accelerometer positioned on the chest, which measures the vibrations generated by isovolumic myocardial contraction. The aim of this paper was to compare noninvasive (accelerometer) versus invasive (LV dP/dt) indices of myocardial contractility in a chronic minipig model of pacing‐induced heart failure (HF). Comparative assessment was performed both at rest and following dobutamine infusion. Methods: In adult male minipigs (n = 6), LV contractility was simultaneously assessed both invasively (LV dP/dt, Millar catheter) and noninvasively (accelerometer) at rest and following dobutamine (up to 7.5 mcg/kg/min), both before and after development of HF by pacing the LV at 180 beats/min for 3 weeks. Results: Invasive and noninvasive assessments were obtained in 24 conditions (12 at rest and 12 after dobutamine infusion). Sensor‐based cardiac force changes were significantly related to positive peak LV dP/dt_max changes following dobutamine infusion both in normal (r = 0.88, P < 0.001) and failing heart (r = 0.89, P < 0.001). The force‐frequency relation showed a tight correlation between invasive and noninvasive assessment (r = 0.68, P = 0.02). Conclusions: The force‐frequency relation can be assessed noninvasively by a transthoracic sensor based on an accelerometer. The method can efficiently detect the development of resting dysfunction and the contractile reserve at different HF steps, with potential for wearable HF monitoring. (PACE 2010; 795–803)     

The First International Stress Echo Symposium

The First International Stress Echo Symposium (held in Pisa, Italy on January 12-14, 1993) was a good occasion for old and new friends to come to Pisa to discuss their work and plan future ventures.     

The value of dipyridamole echocardiography in risk stratification before vascular surgery: A multicenter study

PURPOSE: Patients undergoing major vascular surgery are at relativelyhigh risk of cardiac events, and pharmacological stress echocardiographyis increasingly used for peri-operative risk strattfication. PATIENTS AND METHODS: One hundred and twenty-one patients undergoing vascular surgery(age 65±7 years) were studied by dipyridamole echocardiographytesting in six different centres. Of the total 136 patients,15 were subsequently excluded because surgery was either cancelled(n=8) or postponed pending cardiac revascularization (n=7) becauseof the presence of a ‘high-risk’ stress echo response(identified ‘a priori’ as a positive dipynidamoleecho cardiography testing with a dipyridamole-time <5 minand/or a peak wall motion score index>2, upon scoring eachsegment from 1=normal to 4=dyskinetic in an 11-segment model) RESULTS: No major complications occurred during dipyridamole echocardiographytesting. Technically adequate images were obtained in all patients;however, in one patient only the low dipyridamole dose (56 Prig.kg^–1 over 4 min) was given to limit side effects. Of the121 patients undergoing surgery 28 (23%) had a positive test.Pen-operative events occurred in nine patients (8%) two deaths,two myocardial infarctions, five cases of unstable angina. Sensitivityand speccificity of dipyridamole echocardiography testing forpredicting cardiac events were 78% and 81%, respectively, witha positive predictive value of 25% and a negative predictivevalue of 98% Dipyridamole echocardiography testing effectivelysingled out patients with, from those without, events, but neitherclinical parameters, such as Detsky score, nor baseline echoparameters, such as resting wall motion score index or ejectionfraction were able to distinguish between such patients. CONCLUSION: In conclusion, dipyridamole echocardiography testing is safeand well tolerated in patients undergoing major vascular surgery,and provides an effective pre-operative screening test for riskstrat fi cation of these patients mainly due to the extremelyhigh negative predictive value. Stress echocardiography is abetter discriminator than clinical and rest echocardiographicvariables.     

Left ventricular performance and ultrasonic myocardial quantitative reflectivity in endurance senior athletes: an echocardiographic study

Young elite athletes often show left ventricular hypertrophy,but normal values of quantitatively evaluated myocardial wallreflectivity. The aim of this study is to assess the acousticpattern of ventricular wall reflectivity, as well as of systolicand diastolic function, in older endurance runners with increasedleft ventricular mass. For this purpose, 12 elite, senior isotonicathletes in full training and 11 normal, age-matched controlswith sedentary life styles were studied. The following parameterswere measured with a commercially available 2D echo-Dopplermachine: end-diastolic diameter, diastolic septum thickness,left ventricular mass index, ejection fraction (by Teicholtzrule); peak E, peak A, E/A ratio, acceleration and decelerationtime of mitral inflow velocity and isovolumic relaxation time. On-line radio frequency analysis was also performed to obtainquantitative operator-independent measurements of the integratedbackscatter signal of the ventricular septum and the posteriorwall. The integrated values of the radiofrequency signals werenormalized for the pericardial interface and expressed in percent(% 2D-1B). In spite of the greater left ventricular mass in athletes versusnormal controls (319±81 vs 225±63 g. m–2,P <0.0005), there were no significant intergroup differencesas regards end-diastolic diameter (50.7±5.1 vs 48.1±5.2mm, P = ns), ejection fraction (75.5±9.3 vs 71.8±9.1%,P = ns), and 2D-1B of septum (22.2±6.9 vs 22.4±7.0,P = ns) and posterior wall (12.5 ±5.6 vs 13.1 ±2.8,P=ns). Endurance athletes when compared with age-matched controls showan increase in left ventricular mass but no significant impairmentof systolic and diastolic function detectable by 2D-echo andDoppler indexes. Furthermore, in the athlete group, the quantitativelyassessed ultrasonic backscatter of myocardial walls (septumand posterior wall) was found to be comparable to controls inspite of a marked increase in wall thickness suggesting thatno significant pathological structural changes occur in theolder athletes' heart.     

Pharmacological Methods Instead of Exercise for the Assessment of Coronary Artery Disease

Due to new knowledge of pathophysiology, diagnosis, and treatment, the clinical approach to the patient with suspected coronary artery disease has deeply changed over the last few years. The central role of functional factors-independent from or in association with organic stenosis-are important in the genesis of myocardial ischemia. On the diagnostic side, the widespread use of new methodologies permits detection of ischemia by means of perfusion, mechanical, and metabolic markers. Drugs such as beta blockers, nitrates, and calcium antagonists, and procedures such as coronary angioplasty, have fostered a new era in which it is crucial not only to document ischemia, but also to understand the underlying mechanism. The present article deals with the most important pharmacological tests that can fit into a modern approach to noninvasive ultrasonic diagnosis of coronary artery disease. (ECHOCARDIOGRAPHY, Volume 8, January 1991)     

Quantitative Texture Analysis in Two-Dimensional Echocardiography

Background: Myocardial reflectivity is abnormally increased in patients with thalassemia major under transfusion treatment, probably due to myocardial iron deposits and / or secondary structural changes. Such increased reflectivity has been detected by both qualitative and subjective analysis of two-dimensional echocardiographic (2-D echo) images and quantitative assessment of integrated backscatter amplitude with noncommercially available ultrasound prototypes. The purpose of this study was to assess the acoustic properties of myocardium in patients with beta-thalassemia major and iron overload by means of quantitative computerized offline textural analysis of conventionally recorded 2-D echo images, and to compare textural data with other qualitative (visual assessment) and quantitative (ultrasound backscatter analysis) approaches for myocardial ultrasound tissue characterization simultaneously applied to these patients. Methods and Results: Thirty-five young patients with thalassemia major, without clinical signs of cardiac failure, and 20 age and sex matched normal controls were studied by echocardiography. Each patient was receiving blood transfusion every 2-3 weeks. Two-dimensional echo images, obtained with a commercially available echocardiograph using the parasternal long-axis view, were digitized offline and analyzed by first and second order texture algorithms applied to regions of interest in the myocardium (septal and posterior wall). The mean gray level value was higher in thalassemic patients than in controls on both the septum (110 ± 25 vs 57 ± 13, arbitrary units on a 0-255 scale; P > 0.01) and posterior wall (91 ± 25 vs 67 ± 18; P > 0.01). Among second order statistical parameters, contrast and angular second moment significantly (P > 0.01) differentiated septal and posterior walls of patients and controls. In thalassemic patients, no consistent correlation was found between wall texture parameters and hematologic (years of transfusions and chelation, number of transfusions), 2-D echo (posterior wall thickness, left ventricular end-diastolic diameter), and Doppler (transmitral E/A waves ratio) parameters. Myocardial walls with visually assessed increased echo reflectivity showed a trend toward higher values of mean gray level when compared with myocardial segments with qualitatively assessed normal reflectivity (septum: 121 ± 26 vs 106 ± 24; posterior wall: 105 ± 23 vs 87 ± 23). Although radiofrequency integrated backscatter has been demonstrated to be capable of identifying thalassemic patients, no significant correlation was found between mean gray level (by texture analysis) and radiofrequency data (septum: r = 0.03; posterior wall: r = 0.09; P = NS for both). Conclusions: Myocardial walls affected by hemochromatosis show ultrasound image texture alterations that may be quantified with digital image analysis techniques and appear mostly unrelated to hematologic and conventional, as well as radiofrequency-based, echocardiographic parameters. These changes in quantitatively evaluated echo reflectivity are present even before the development of clinical and echocardiographic signs of cardiac dysfunction.