Cataldo Memmola

Transesophageal Doppler echocardiography evaluation of coronary blood flow velocity in baseline conditions and during dipyridamole-induced coronary vasodilation.

Transesophageal echocardiography allows the evaluation of proximal coronary artery anatomy and coronary blood flow velocity (CBFV). To assess the potential of transesophageal echocardiography in evaluating CBFV and its variations induced by coronary-active drugs, we studied 15 patients by high-quality pulsed wave Doppler recordings of CBFV. In these patients, transesophageal Doppler evaluation of CBFV was performed before, 2 minutes after cessation of dipyridamole infusion (0.56 mg/kg in 4 minutes), and 2 minutes after aminophylline infusion (240 mg injected 4 minutes after cessation of dipyridamole infusion). The following CBFV parameters were evaluated at each of the three steps of the study protocol: maximal and mean diastolic velocities and maximal and mean systolic velocities. Furthermore, the following indexes of coronary flow reserve were evaluated: the ratio between maximal diastolic velocity recorded after and before dipyridamole administration and the ratio between mean diastolic velocity recorded after and before dipyridamole administration. Nine of the 15 patients had a normal left anterior descending coronary artery (group A), whereas the remaining six had significant (less than or equal to 75%) stenosis (group B). In group A patients, all CBFV parameters increased significantly during dipyridamole infusion and returned to near baseline values after aminophylline infusion. In group B patients, on the other hand, none of the CBFV parameters increased after dipyridamole infusion. Dipyridamole/baseline maximal diastolic velocity and mean diastolic velocity ratios were, respectively, 3.22 +/- 0.96 and 3.04 +/- 0.88 in group A and 1.46 +/- 0.45 (p less than 0.01 versus group A) and 1.48 +/- 0.49 (p less than 0.01 versus group A) in group B patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary flow dynamics and reserve assessed by transesophageal echocardiography in obstructive hypertrophic cardiomyopathy

Myocardial ischemia is frequently associated with left ventricular outflow obstruction. To assess coronary flow impairment in obstructive hypertrophic cardiomyopathy (HC), 10 patients with echo-Doppler-detected obstructive HC and normal coronary arteries underwent transesophageal echo-Doppler examination of both coronary flow velocity (CFV) at rest, recorded in the proximal left anterior descending coronary artery, and coronary flow reserve (CFR) evaluated by means of dipyridamole infusion response. Ten normal patients were similarly studied and served as a control group. Two relevant alterations in coronary flow dynamics were detected in patients with HC: (1) a significantly increased diastolic/systolic CFV ratio, and (2) a significantly reduced dipyridamole/baseline CFV ratio. Compared with normal subjects, the CFV pattern showed a significantly greater diastolic and a significantly lower systolic component at rest (in some patients it was reversed). Diastolic/systolic CFV ratio was significantly higher in patients with HC at baseline (3.1 +/- 1 vs 1.6 +/- 0.5; p < 0.01) and increased further after dipyridamole infusion (4.9 +/- 2 vs 2.2 +/- 0.7; p < 0.01). In addition, CFR was impaired in patients with HC (1.8 +/- 0.3 vs 3.1 +/- 0.5; p < 0.01). Furthermore, a significant correlation between CFR and intraventricular pressure gradient was found. Thus, transesophageal echo-Doppler examination is a useful tool for evaluating CFV dynamics and CFR as demonstrated in patients with obstructive HC.

Detection of Proximal Stenosis of Left Coronary Artery by Digital Transesophageal Echocardiography: Feasibility, Sensitivity, and Specificity

To assess feasibility, sensitivity, and specificity of transesophageal echocardiography (TEE) in visualizing proximal left coronary artery segments (entire left main, proximal left anterior descending, and circumflex) and in identifying proximal coronary stenosis, 160 consecutive patients were studied. Each patient underwent TEE before coronary angiography; the echocardiographic images were digitized and reviewed in a continuous cineloop format. The entire proximal left coronary artery was adequately imaged in 111 patients (70%). A stenosis was considered to be present at TEE if hyperreflecting plaques narrowing the coronary lumen were observed. TEE observed the presence of a stenosis in 6 of 6, 50 of 63, and 13 of 24 patients with stenosis detected at angiography on the left main, left anterior descending, and circumflex, respectively, and 2 of 105, 5 of 48, and 14 of 87 patients without angiographically detectable coronary stenosis in corresponding coronary segments. Thus, sensitivity and specificity of TEE in identifying stenosis of the left main coronary artery, proximal left anterior descending artery, and proximal circumflex artery were 100% and 98%, 79% and 89%, 54% and 84%, respectively. In conclusion, TEE identification of the proximal left coronary artery is feasible in most patients. Accuracy in identifying significant proximal stenosis varies from segment to segment and is higher for the left main coronary artery.

Visualization of the Coronary Artery Using Transesophageal Echocardiography

The left main coronary artery, its bifurcation, and the proximal part of both the left anterior descending and the circumflex coronary arteries can be visualized by two-dimensional echocardiography (Chen et al. 1980; Douglas et al. 1988; Presti et al. 1987; Rink et al. 1982; Rogers et al. 1980a, b; Ryan et al. 1986). Several studies have demonstrated that this technique enables one to investigate the proximal left coronary tree and to diagnose significant coronary artery disease with variable sensitivity and specificity by recognising high-intensity infraluminal echoes which are very probably due to the calcification of the arterial walls (Presti et al. 1987; Rink et al. 1982; Rogers et al. 1980; Ryan et al. 1986).

Early onset of heparin-induced thrombocytopenia with thrombosis after open heart surgery: importance of an early diagnosis and Lepirudin treatment.

Heparin-induced thrombocytopenia with thrombosis (HITT) is a rare complication of cardiac surgery with cardiopulmonary bypass. We report two cases of HITT treated with the direct thrombin inhibitor Lepirudin. Immediate diagnosis was essential to prompt heparin discontinuation and successful early Lepirudin administration in the first case. In the second, the presence of an intra-aortic balloon pump delayed HITT recognition, and Lepirudin infusion could not prevent limb amputation. In both cases HITT occurred earlier (< 5 days after heparin exposure) than its usual presentation.

Transesophageal echo-Doppler studies of coronary arteries — identification, assessment of flow reserve and value of contrast enhancement

Blood flow in the left coronary artery usually has a biphasic pattern with a greater diastolic and a smaller systolic component. The diastolic component is greater because in diastole coronary resistance is lower and the pressure gradient between the aortic root and left ventricle (i.e. the driving pressure) is higher. The amount of coronary blood flow (or flow velocity), its baseline characteristics and the changes induced by drugs capable of decreasing coronary resistance (and thus increasing forward flow) represent an important aspect of clinical and research cardiology studies. A better understanding of coronary pathophysiology is, in fact, extremely useful for the comprehension of the underlying angina mechanisms in some non “coronary artery diseases” characterized by effort chest pain (patients with reduced coronary flow reserve), for the evaluation of the effects of coronary active drugs and for the assessment of resting flow alterations in coronary arteries produced by different cardiac diseases.

Coronary anatomy and myocardial perfusion: Role of contrast echocardiography

Coronary stenoses reduce coronary flow and, consequently, myocardial perfusion. This is the main cause of clinical symptoms of coronary artery disease. Though coronary arteriography is the most important diagnostic examination for evaluating this disease, it does have several limitations. It cannot, for example, estimate the actual ‘haemodynamic’ severity of the coronary stenoses and, therefore, its real significance in limiting myocardial perfusion. Interpretation of coronary angiograms is also affected by an intra- and inter-observer variability which cannot be overlooked [1, 2]. Furthermore, coronary arteriography as performed in most institutions gives only qualitative information on the distribution and characteristics of coronary stenoses. Myocardial perfusion is further influenced by many other factors which cannot be evaluated by coronary angiography (the microcirculation, heart muscle conditions, interstitial characteristics, wall stress, collateral circulation etc.).

901-52 Ultrasonic Integrated Backscatter Cyclic Variations During Atrial Pacing in Patients with and without Coronary Artery Disease

Contraction and relaxation of normal myocardium are associated with parallel integrated backscatter cyclic variations (IB CV). It has been demonstrated that IB CV are reversibly reduced in magnitude during coronary occlusion and reperfusion. To evaluate in humans the effects of pacing-induced ischemia on IB Cv, 29 pts were studied with multiplane TEE and simultaneous atrial pacing (up to 150 beats/m’). A prototype (Hewlett-Packard AD system) was used to acquire and analyse IB images. In each pt a transgastric 2 chamber view was acquired at rest, at peak-pacing and 5 cardiac cycles after pacing interruption (recovery). Twenty-one pts had significant coronary stenosis (≥50% narrowing): 8 pts developed myocardial ischemia (chest pain, ECG changes and wall motion abnormalities) during atrial-pacing [Group A], while the remaining 13 pts did not [Group B]. Eight pts had normal coronaries and no myocardial ischemia during pacing [Group C]. IB CV analysis was performed only in myocardial segments perpendicular to ultrasonic beam (anterior and inferior wall in transgastric view). In group A and B pts only segments within a territory supplied by a stenotic coronary artery were considered. Results IB CV are expressed in decibel units Download high-res image (64KB) Download full-size image Conclusion atrial pacing does not affect IB CV in myocardium supplied by normal coronary arteries. During pacing, IB CV are blunted in myocardium supplied by significantly narrowed coronary arteries, even in the absence of traditional signs of ischemia. IB CV have a potential in the identification of stress-induced regional left ventricular dysfunction in pts with coronary artery disease.

Stress echocardiography for identifying patients at risk after myocardial infarction

Several factors contribute to the prognosis of patients surviving acute myocardial infarction [1–3]. Among these, the presence of additional myocardium at jeopardy is felt to be one of the most important. Consequently, many stress tests have been developed and proposed over the last few years for evaluating patients with recent myocardial infarction [1–9]. These tests are based on the combined use of a stress capable of inducing ischemia and a diagnostic technique capable of detecting the direct or indirect signs of acute myocardial ischemia. Among the stress tests used so far for prognostically stratifying patients with recent myocardial infarction, exercise echocardiography (treadmill or bicycle) is certainly the most common.

Evaluation of proximal left coronary artery anatomy and blood flow using digital transesophageal echocardiography

Non-invasive evaluation of the proximal left coronary artery can be obtained by two-dimensional echocardiography [1–6]. Even if the feasibility of this kind of evaluation has been demonstrated, its clinical application has not yet obtained wide acceptance because of some difficulties that considerably hamper echocardiographic imaging of coronary arteries. First of all, review¬ing and evaluation of real time 2D Echo images of the coronaries is troublesome because of the cyclic movement of the heart that does not allow con¬tinuous monitoring of a tubular structure as small as the coronary artery; furthermore, the quality of echocardiographic images is very often poor and, therefore, does not allow accurate definition of the coronary boundaries.