Detection of coronary artery disease by digital stress echocardiography: comparison of exercise, transesophageal atrial pacing and dipyridamole echocardiography.

OBJECTIVES: This study assessed and compared the diagnostic potential of exercise, transesophageal atrial pacing and dipyridamole stress echocardiography in a clinical setting. BACKGROUND: Although they have been widely studied, no data exist with regard to comparisons of these procedures in a head-to-head study in different clinical settings. METHODS: One hundred four consecutive patients with suspected coronary artery disease undergoing coronary angiography and with no previous myocardial infarction or rest left ventricular wall motion abnormalities underwent digital posttreadmill, transesophageal atrial pacing and dipyridamole echocardiography. RESULTS: Feasibility of digital exercise echocardiography was 84%; 8 of 88 remaining patients had a nondiagnostic exercise echocardiographic test (inadequate exercise or imaging). In 80 patients with feasible and diagnostic digital exercise echocardiography, sensitivity, specificity and accuracy were, respectively, 89%, 91% and 90%. Eighty of the 104 patients underwent transesophageal atrial pacing and dipyridamole echocardiography. Feasibility of the alternative stress procedures was 77% for transesophageal atrial pacing and 96% for dipyridamole. In 60 patients successfully undergoing both alternative stress procedures, sensitivity and specificity were 83% and 76% for atrial pacing and 43% and 92% for dipyridamole echocardiography, respectively. In the group of 24 patients with nondiagnostic exercise echocardiography and consequent indication to alternative stress procedures, accuracy of transesophageal atrial pacing was higher than that of dipyridamole echocardiography (73% vs. 45%, p = 0.06). CONCLUSIONS: Because of its higher diagnostic potential and additional functional information, exercise is the stress of choice when stress echocardiography is used to detect the presence of coronary artery disease. Alternative stresses can be used in patients with nondiagnostic exercise echocardiography. Transesophageal and dipyridamole echocardiography differ in feasibility and diagnostic reliability (higher sensitivity of transesophageal atrial pacing, higher specificity of dipyridamole). These characteristics must be considered when selecting procedures to be used as alternatives to exercise.

[Echo-Doppler evaluation of the internal mammary artery bypass on the left coronary artery: a 4-year follow-up]. / Valutazione eco-Doppler del bypass di arteria mammaria interna su coronaria sinistra: 4 anni di follow-up.

In this study ultrasonographic techniques are suggested to monitor internal mammary artery bypass graft on the anterior descending coronary artery. One hundred and fourty patients were studied using 3 different ultrasonographic methods: zero-crossing continuous wave Doppler, fast Fourier transform (FFT) continuous wave Doppler and high resolution echo-Doppler. The patients underwent the ultrasonographic examinations 3 times a year for 4 years. By means of FFT Doppler analysis and echo-Doppler it was possible to perform the study in 138 patients and by zero-crossing system in 127 patients. Ultrasonographic techniques showed pathologies of the graft in 17 (13%) patients: 15 with obstructive pathologies and 2 with haemodetournament of the second intercostal artery.

Patterns of atrioventricular conduction during postexercise recovery in patients with atrial fibrillation and Wolff-Parkinson-White syndrome.

The effects of the postexercise recovery phase on the functional anterograde conduction properties of the accessory pathway (AP) were evaluated. Twenty-nine patients with Wolff-Parkinson-White (WPW) syndrome were submitted to supine maximal bicycle exercise testing. In seven patients (group I), in whom sustained atrial fibrillation (AF) could be induced by transesophageal pacing (TP), mean ventricular rate (MVR), the shortest R-R interval (SRR) between preexcited beats, and the observed percentage of preexcited beats were evaluated at rest, after each step of exercise and 2 minutes after the end of exercise. In 22 patients (group II), in whom sustained AF could not be induced, decremental TP was performed to evaluate the shortest atrial cycle length (SCL) with 1:1 conduction over AP at rest, after each step of exercise, and 2 minutes after the end of exercise. In four patients in group I, the protocol was repeated with atropine injected during the last minute of exercise. In 12 patients (three from group I and nine from group II), catecholamine plasma levels were measured at rest, at peak exercise, and during recovery. MVR was 144 +/- 20 beats/min at rest, 186 +/- 21 beats/min at peak exercise (P less than 0.001 vs rest), and 179 +/- 21 beats/min during recovery (P less than 0.001 vs rest; P less than 0.05 vs peak exercise). SRR was 289 +/- 73 msec at rest, 223 +/- 25 msec at peak exercise (P less than 0.05 vs rest), and 227 +/- 29 msec during recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

[Blood acceleration is the principal factor in coronary flow increase during exercise test]. / L'accelerazione ematica è il principale fattore di aumento del flusso coronarico durante test da sforzo.

Continuous wave Doppler evaluation of the blood flow velocity in the internal mammary artery anastomosed to the left anterior descending coronary artery is a technique for assessing human coronary flow that shows a good reproducibility and lower change in Doppler angle between resting and supine exercise conditions. In this study the reciprocal changes which occur in coronary blood flow, coronary stroke volume, coronary resistance and blood pressure have been studied. During supine exercise coronary stroke volume remains constant and the increase of blood cells acceleration is necessary to have the shortening of cardiac cycle. This parameter is inversely dependent on the coronary resistances and directly dependent on blood pressure. As a consequence it plays the main role in increasing coronary blood flow during exercise.

[Doppler velocimetry of the internal mammary artery anastomosed to the anterior descendent coronary artery: a noninvasive analysis of coronary circulation]. / Velocimetria Doppler dell'arteria mammaria interna anastomizzata sulla discendente anteriore: analisi non invasiva della circolazione coronarica.

This study analyses the static and dynamic characteristics of the flow curves obtained by continuous wave Doppler flow velocity analysis in the internal mammary artery (IM) under normal conditions and after left anterior descending coronary artery by-pass. The IM flow velocity curve has the characteristics of a muscular artery both in basal conditions and during hyperventilation and Valsalva manoeuvre. On the other hand, the by-passed IM shows a typically phasic flow velocity curve, the diastolic flow prevailing over the systolic as is commonly the case in the coronary circulation. This curve also shows variations characteristic of the coronary circulation during Valsalva manoeuvre, whereas it is not affected by the alterations induced by hyperventilation in the area of the respiratory muscles. Continuous wave Doppler flow analysis of the by-passed IM can therefore be considered a reliable method for evaluating coronary flow in man. The fact that this method is non-invasive makes it obviously advantageous and widens its field of application not only to strictly diagnostic evaluations but also to physiopathological and therapeutical ones.

Electrophysiological properties of intravenous metoprolol in man.

Electrophysiological changes produced by intravenous (0.1 mg/kg) metoprolol, a new selective beta 1-blocking agent devoid of intrinsic activity, were studied in 16 subjects with estimated normal impulse formation and conduction. The most important effects were sinus bradycardia, mild increase of sinoatrial conduction time, depression of intranodal conduction, and prolongation of AV node refractory periods. Sinus node recovery time and atrial refractory periods were unmodified. Infranodal conduction and the refractory periods of the His-Purkinje system, as well as of the bundle-branches, were unchanged. These effects are compared with those observed after intravenous propranolol, pindolol, and oxprenolol.