Value of intraoperative left ventricular microbubbles detected by transesophageal two-dimensional echocardiography in predicting neurologic outcome after cardiac operations

To determine whether the presence or absence of left ventricular (LV) intracavitary microbubbles during cardiac surgery predicts neurologic sequelae, 82 patients undergoing cardiac surgery were studied using transesophageal 2-dimensional (2-D) echocardiography. Cross-sectional images were recorded just before and immediately after cardiopulmonary bypass and stop frames were reviewed for the presence of microbubbles, rated as: 0 = absent, 1 = fewer than 5/frame, 2 = 10 to 25/frame, 3 = too numerous to count. Microbubbles were detected after cardiopulmonary bypass in 34 patients (41%) and found more often in valvular or other intracardiac manipulations than in coronary revascularization, 30 of 40 vs 4 of 42, respectively (p less than 0.001). When grade 2 or 3 microbubbles were identified (22 of 34 patients), mechanical attempts to eradicate them were not successful. Postoperative follow-up in all patients revealed no new focal neurologic deficits. Prolonged encephalopathy (confusional state more than 72 hours) occurred in 4 of 48 patients with no detectable microbubbles and in 3 of 34 patients with microbubbles (difference not significant). Thus, intracavitary left ventricular microbubbles are often detected during cardiac operations, particularly during valve replacement, but are not predictive of postoperative neurologic complications. This is true even if microbubbles are densely concentrated; attempts to eradicate microbubbles are unsuccessful and may be unnecessary.     

Real-time, intracardiac, two-dimensional echocardiography: enhanced depth of field with a low-frequency (12.5 mhz) ultrasound catheter

Advances in catheter-based ultrasound imaging technology allow for a unique opportunity to develop two-dimensional intracardiac echocardiography, an imaging method that could have significant clinical applications. In this study, we evaluated the potential of a new, percutaneous, 9-Fr prototype intracardiac echocardiographic catheter with a 12.5-MHz rotating crystal in 13 dogs. In all dogs, we were able to easily advance the intracardiac echocardiographic catheter into the right and left hearts percutaneously and obtain dynamic images of cardiac structures in various imaging planes. With the intracardiac echocardiographic catheter in the right atrium, the whole chamber could be visualized. Minor manipulation allowed visualization of the right atrium, right ventricle, and tricuspid valve in a two-chamber view; further maneuvering yielded four-chamber views. With advancement of the catheter into the right ventricle and pulmonary artery, the right ventricular cavity, right ventricular outflow tract, and pulmonary artery could be imaged. The intracardiac echocardiographic catheter in the aortic root allowed visualization of the pulmonary artery and its bifurcation, superior portions of the atria, interatrial septum, aortic valve, and the proximal left coronary artery. With the intracardiac echocardiographic catheter in the left ventricle, short-axis images of the whole left ventricle were obtained. Manipulating the catheter tip within the left ventricle, we could visualize the left ventricle, left atrium (LA), and the mitral valve in the long axis. We were also able to visualize and identify experimentally-induced ischemic regional left ventricular dyskinesis (four of of five dogs), aortic valvular tear (five out of five dogs), and pericardial effusion with right atrial collapse (two out of two dogs). Intracardiac echocardiography was not associated with any complications. We conclude that percutaneous, low-frequency intracardiac echocardiography with a 12.5-MHz, 9-Fr catheter yields cardiac images in many imaging planes with a good depth of field, allows identification of valvular, myocardial, and pericardial abnormalities, and has excellent clinical potential in the assessment of many cardiovascular disorders.     

Ultrasonic enhancement of myocardial infarction with perfluorocarbon compounds in dogs

Medically pure (100%) carbon dioxide directly injected into a peripheral vein was used for 2-dimensional contrast echocardiography in 134 patients with an arteriovenous shunt demonstrated by cardiac catheterization and cineangiography, Qp/Qs ratios of 1.5 to 3.7, pulmonary-to-systemic peak systolic pressure ratios of 0.2 to 0.8 and no oximetrically demonstrable venoarterial shunt. Two patients with transposition of the great arteries, intact ventricular septum and a Senning operation as well as 30 normal subjects of comparable age also were studied. In patients with an atrial septal defect, the gas microbubbles opacified the left atrium. In patients with a ventricular septal defect, the gas microbubbles opacified the left ventricle, whereas the left atrium was free of contrast. In all patients with patent ductus arteriosus, the gas microbubbles opacified the abdominal aorta, whereas the left atrium, left ventricle, aortic root and aortic arch remained free of contrast. In 2 patients in whom an aneurysm of the sinus of Valsalva ruptured into the right ventricle, the "negative" contrast effect permitted localization of the shunt. In 2 patients with transposition of the great arteries, an intact ventricular septum and a Senning operation, the intracardiac flow pattern was clearly demonstrated. No complication was observed. We conclude that pure carbon dioxide directly injected into a peripheral vein is a safe and advantageous echocardiographic contrast material. Because of its greater diffusibility in comparison with oxygen and fluid contrast media, small venoarterial shunting can be detected in defects such as atrial septal defect, ventricular septal defect and patent ductus arteriosus, in which only an arteriovenous shunt can be demonstrated by oximetry.     

The ventricular A wave: a new echocardiographic index of late diastolic filling of the left ventricle.

Echocardiography was used to evaluate the late diastolic filling period of the left ventricle in 30 normal individuals, 25 patients with left ventricular hypertrophy, normal sinus rhythm, and either a normal or delayed mitral valve closure, and 15 patients with atrial fibrillation. The echocardiographic ventricular A wave (VAW) was defined as the difference between the end-diastolic and an earlier late-diastolic internal left ventricular dimension, and it was felt to primarily reflect the atrial contribution to late diastolic filling of the left ventricle. It disappeared during ventricular pacing and was significantly smaller than normal in patients with atrial fibrillation. The VAW was significantly larger in patients with left ventricular hypertrophy and normal mitral valve closure reflecting the greater contribution by atrial contraction to late diastolic filling in these patients. In patients with left ventricular hypertrophy and delayed mitral valve closure, the VAW was normal reflecting lesser ventricular enlargement with atrial contraction than in the other patients with left ventricular hypertrophy. This suggested a greater impairment to left ventricular filling in these patients. Therefore, the VAW appears to be an indicator of abnormalities of late diastolic filling caused by left ventricular hypertrophy.     

Role of transoesophageal echocardiography in evaluation of cardiogenic embolism.

OBJECTIVE--To determine the value of transoesophageal echocardiography in the assessment of selected patients at risk of cardiogenic embolism or after it. DESIGN--Prospective comparison of the results of transoesophageal and transthoracic echocardiography. Transoesophageal echocardiography was performed with a 5 MHz single plane phased array transducer. SETTING--University teaching hospital. PATIENTS--100 patients referred for transoesophageal echocardiography after a cerebral ischaemic event or peripheral arterial embolism (n = 63), before percutaneous balloon dilatation of the mitral valve (n = 23), or before electrical cardioversion of atrial fibrillation (n = 14). RESULTS--Transthoracic echocardiography showed potential sources of embolism in four patients including left ventricular thrombus in two patients (with one false positive), left atrial appendage thrombus (n = 1), and patent foramen ovale (n = 1). Transoesophageal echocardiography showed 59 potential embolic sources in 45 patients including left atrial spontaneous echo contrast (n = 33), left atrial appendage thrombus (n = 13), left ventricular thrombus (n = 5), patent foramen ovale (n = 3), left ventricular spontaneous echo contrast (n = 2), mitral valve prosthesis thrombus (n = 1), mitral valve prolapse (n = 1), and pronounced aortic atheroma (n = 1). Transoesophagal echocardiography showed potential embolic sources in 36/53 (68%) patients with atrial fibrillation compared with 9/47 (19%) patients in sinus rhythm. Percutaneous balloon dilatation of the mitral valve was performed without embolic complications in 18 patients without left atrial thrombi and in three patients with small fixed thrombi in the left atrial appendage. It was cancelled in two patients with large thrombi in the left atrial appendage. Cardioversion was performed without embolic complications in 14 patients without left atrial thrombi. CONCLUSIONS--Transoesophageal echocardiography detects potential sources of embolism better than transthoracic echocardiography in selected patients at risk of cardiogenic embolism or after it.     

Role of transoesophageal echocardiography in evaluation of cardiogenic embolism.

OBJECTIVE--To determine the value of transoesophageal echocardiography in the assessment of selected patients at risk of cardiogenic embolism or after it. DESIGN--Prospective comparison of the results of transoesophageal and transthoracic echocardiography. Transoesophageal echocardiography was performed with a 5 MHz single plane phased array transducer. SETTING--University teaching hospital. PATIENTS--100 patients referred for transoesophageal echocardiography after a cerebral ischaemic event or peripheral arterial embolism (n = 63), before percutaneous balloon dilatation of the mitral valve (n = 23), or before electrical cardioversion of atrial fibrillation (n = 14). RESULTS--Transthoracic echocardiography showed potential sources of embolism in four patients including left ventricular thrombus in two patients (with one false positive), left atrial appendage thrombus (n = 1), and patent foramen ovale (n = 1). Transoesophageal echocardiography showed 59 potential embolic sources in 45 patients including left atrial spontaneous echo contrast (n = 33), left atrial appendage thrombus (n = 13), left ventricular thrombus (n = 5), patent foramen ovale (n = 3), left ventricular spontaneous echo contrast (n = 2), mitral valve prosthesis thrombus (n = 1), mitral valve prolapse (n = 1), and pronounced aortic atheroma (n = 1). Transoesophagal echocardiography showed potential embolic sources in 36/53 (68%) patients with atrial fibrillation compared with 9/47 (19%) patients in sinus rhythm. Percutaneous balloon dilatation of the mitral valve was performed without embolic complications in 18 patients without left atrial thrombi and in three patients with small fixed thrombi in the left atrial appendage. It was cancelled in two patients with large thrombi in the left atrial appendage. Cardioversion was performed without embolic complications in 14 patients without left atrial thrombi. CONCLUSIONS--Transoesophageal echocardiography detects potential sources of embolism better than transthoracic echocardiography in selected patients at risk of cardiogenic embolism or after it.     

Problems in echocardiographic volume determinations: echocardiographic-angiographic correlations in the presence of absence of asynergy.

The relation of minor and major axes of the left ventricle was determined in 100 left ventriculograms performed in the right anterior oblique projection. This relation taken over a wide range of volumes was used to derive a theoretically correct equation for determination of ventricular volume by echocardiography. The final equation was: V =[7.0/2.4 +d] (D3), where V = volume and D = the echocardiographically measured internal dimension. In 12 patients without asynergy, this equation accurately and directly calculated end-systolic and end-diastolic volumes whether the left ventricle was small or large. However, in 12 patients exhibiting left ventricular asynergy the correlation between angiographically and echocardiographically determined volumes was poor. Thus, caution is recommended in the use of time-motion echocardiography to calculate ventricular volumes in patients with coronary artery disease and possible left ventricular asynergy.     

Noninvasive coronary imaging and assessment of left ventricular function using 16-slice computed tomography

In recent years, multislice computed tomography (MSCT) has been demonstrated to be a feasible imaging modality for noninvasive coronary angiography and left ventricular function analysis. The present study evaluated overall performance of 16-slice MSCT in the detection of significant coronary artery disease, stent, or bypass graft stenosis in combination with global left ventricular function analysis. Forty-five patients underwent 16-slice MSCT. Multislice computed tomograms were used to evaluate the presence of significant coronary artery stenoses (>/=50% decrease in luminal diameter) in native coronary segments, bypass grafts, and coronary stents and were compared with conventional coronary angiograms. In addition, left ventricular ejection fraction was calculated and compared with 2-dimensional echocardiography. MSCT was performed successfully in all patients. A close correlation between MSCT and 2-dimensional echocardiography was demonstrated for the assessment of left ventricular ejection fraction (y = 0.93x +3.33, r = 0.96, p <0.001). A total of 298 of native coronary artery segments (94%) were evaluated with MSCT, whereas 81 of 94 grafts (85%) and 41 of 52 coronary stents (79%) were also evaluated. For all segments, overall sensitivity, specificity, and positive and negative predictive values were 85%, 89%, 71%, and 95%, respectively. In conclusion, 16-slice MSCT is a feasible modality for noninvasive evaluation and exclusion of coronary artery disease in patients who present with chest pain.     

Coronary arteriovenous fistula complicating aortocoronary bypass surgery

A coronary artery fistula complicating aortocoronary bypass surgery is reported in a patient. A continuous murmur heard on follow-up visits was the important clinical clue. The diastolic murmur was localized by intracardiac phonocardiography to the area of the tricuspid valve. A small left-to-right shunt was demonstrated in the right ventricle. Angiographic studies demonstrated a saccular structure arising from the left anterior descending artery, just distal to the anastomotic site and communicating with the right ventricle through a maze of vessels.     

Prognostic significance of clinically silent coronary artery fistulas

Symptomatic coronary artery fistulas (CAF) are associated with significant morbidity and mortality. With the advent of high-resolution 2-dimensional and color Doppler echocardiography, the detection rate of clinically silent CAF has increased, but their clinical significance and outcome have not been defined. The clinical, echocardiographic, electrocardiographic, and angiographic findings and documented follow-up of 31 patients with an echocardiographic finding of a clinically silent coronary artery fistula from 1986 to 1997 were analyzed. Mean age at diagnosis was 7.2+/-8.4 years. Indications for echocardiography were murmur (n = 23), congenital heart disease (n = 2), cardiomegaly (n = 2), chest pain (n = 1), stridor (n = 1), syncope (n = 1), and chest trauma (n = 1). CAF were detected with color Doppler flow mapping in all patients. The origin of the fistula was from the left coronary artery system (n = 27), right coronary artery system (n = 3), and bilateral (n = 1). The exit sites were the pulmonary artery (n = 18), right ventricle (n = 8), right atrium (n = 2), and left ventricle (n = 3). Global and regional left ventricular function were normal in all patients at presentation and follow-up. Spontaneous closure of the fistula was documented in 7 patients (23%) at mean follow-up of 2.6+/-2.0 years. In 23 patients the fistula persisted without intervention. All patients remained asymptomatic, without adverse clinical events or evidence of ischemia at a mean age at follow-up of 9.3+/-9.1 years (range 4 months to 42.0). Based on this experience, there is no evidence that clinically silent CAF diagnosed incidentally by color Doppler echocardiography are associated with adverse clinical outcome in childhood and adolescence. Conservative management with continued follow-up of these patients appears to be appropriate.     

Surgically treated intraoperative coronary embolism

We report a case of intraoperative coronary embolism in a 52-year-old male patient undergoing mitral valve replacement. The patient had persistent atrial fibrillation and was treated with oral anticoagulants and, in spite of well controlled anticoagulation, he suffered a transient ischemic attack. No intracardiac thrombus was found by transthoracic echocardiography. Three weeks later open heart surgery was performed. During valve surgery no thrombus was found in the left atrium. When cardiopulmonary bypass was discontinued the heart function rapidly deteriorated and the heart swelled up, became bluish, with left atrial pressure rising to 40 mm Hg. It was noticed that the anterior surface of the left ventricle was not moving. Coronary embolism was considered. Multiple thrombi were found and removed from the left anterior coronary artery. After successful thrombectomy the patient came off the pump easily. Early and late postoperative course were uneventful. Intraoperative coronary embolism should be considered when cardiac function is deteriorating and there is an inability to wean the patient from the pump. Early and correct diagnosis is lifesaving.     

Coronary artery abnormalities and right ventricular histology in hypoplastic left heart syndrome.

OBJECTIVES. To determine whether right ventricular preservation is compromised in any anatomic subgroup of hypoplastic left heart syndrome, we assessed the coronary artery anatomy and myocardial histologic features of 151 postmortem specimens with hypoplastic left heart syndrome. BACKGROUND. Although previous studies have shown that coronary artery abnormalities are more prominent in the subgroup of patients who have a patent mitral valve and obstructed aortic valve, it has not been established that these abnormalities compromise right ventricular perfusion. METHODS. Eighty-nine specimens with a patent mitral valve and aortic atresia, 52 with mitral and aortic atresia and 10 with patent mitral and aortic valves were examined. Histologic sections of the right ventricle, left ventricle and coronary arteries were obtained from 64 study hearts and 5 control hearts. RESULTS. Gross coronary anomalies included coronary-cameral communications (n = 29), single left coronary artery (n = 2), single right coronary artery (n = 1) and tortuosity (n = 19). Coronary-cameral communications and tortuosity were significantly associated with the subgroup that had mitral hypoplasia and aortic atresia. Coronary artery wall thickness relative to lumen diameter was not different among the subgroups. No areas of coronary artery stenosis or interruption were discovered. Although endocardial fibroelastosis of the left ventricle was strongly associated with the mitral hypoplasia and aortic atresia group, the right ventricular histologic findings were similar in all subgroups and were not differentially affected by older age. CONCLUSIONS. Although the incidence of coronary abnormalities is greater in patients with mitral hypoplasia and aortic atresia, in this study there was no apparent difference in perfusion of the right ventricle among the anatomic subgroups of hearts with hypoplastic left heart syndrome.     

Mitralinsuffizienz

Mitral regurgitation is the second most frequent reason for valve surgery. The most important causes of mitral regurgitation are degenerative valve disease (mitral valve prolapse), left ventricular impairment and dilatation (in coronary artery disease or dilated cardiomyopathy), and infective endocarditis. The regurgitation of blood from the left ventricle into the left atrium leads to dilatation of the left atrium, increase in pulmonary capillary pressure and pulmonary congestion. In chronic severe mitral regurgitation, the left ventricle dilates and becomes impaired over time. Key symptoms are fatigue and dyspnea on exertion. The most prominent physical sign is the characteristic systolic murmur. Echocardiography identifies severity, delineates morphology, and estimates the impact of mitral regurgitation on left ventricular function. Importantly, echocardiography identifies candidates for mitral valve repair. Symptomatic patients and asymptomatic patients with impaired left ventricular function should be operated. If possible, valve repair is preferred over valve replacement to better preserve left ventricular function and to avoid the need for postoperative anticoagulation (except if atrial fibrillation persists).     

Mitral regurgitation

Mitral regurgitation is the second most frequent reason for valve surgery. The most important causes of mitral regurgitation are degenerative valve disease (mitral valve prolapse), left ventricular impairment and dilatation (in coronary artery disease or dilated cardiomyopathy), and infective endocarditis. The regurgitation of blood from the left ventricle into the left atrium leads to dilatation of the left atrium, increase in pulmonary capillary pressure and pulmonary congestion. In chronic severe mitral regurgitation, the left ventricle dilates and becomes impaired over time. Key symptoms are fatigue and dyspnea on exertion. The most prominent physical sign is the characteristic systolic murmur. Echocardiography identifies severity, delineates morphology, and estimates the impact of mitral regurgitation on left ventricular function. Importantly, echocardiography identifies candidates for mitral valve repair. Symptomatic patients and asymptomatic patients with impaired left ventricular function should be operated. If possible, valve repair is preferred over valve replacement to better preserve left ventricular function and to avoid the need for postoperative anticoagulation (except if atrial fibrillation persists).     

Atrial transport function in coronary artery disease: relation to left ventricular function

The atrial contribution to ventricular stroke volume was evaluated in 50 patients with coronary artery disease and found to be related to left ventricular function. All patients underwent complete hemodynamic and angiographic studies. Angiographic volume studies were utilized to determine atrial contribution to the stroke volume, end-systolic volume and ejection fraction. In 11 patients without heart disease, atrial contribution to stroke volume was (mean value +/- standard deviation) 9.3 +/- 6 ml/m2 compared with 13.5 +/- 6 ml/m2 in the patients with coronary disease (probability [p] less than 0.05). The percent of atrial contribution to stroke volume was 20 +/- 7 and 33 +/- 11%, respectively, in normal subjects and patients with coronary disease (p less than 0.05). The combination of congestive heart failure and cardiomegaly was the only clinical aspect associated with a significantly higher (p less than 0.05) atrial contribution to stroke volume than that in the remaining patients with coronary disease (46 versus 31%). Relating the atrial contribution to stroke volume to the left ventricular end-diastolic pressure, stroke volume, end-systolic volume and ejection fraction revealed correlation coefficients of 0.30, -0.44, 0.56 and -0.64, respectively. No patient with a normal ejection fraction (greater than 0.50) had an atrial contribution greater than 40% of stroke volume. The ratio of peak left ventricular systolic pressure/end-systolic volume (mm Hg/ml) was 2.7 +/- 1.5 in patients (n = 14) with an atrial contribution greater than 40% of stroke volume compared with 5.3 +/- 3.4 in patients having an atrial contribution of 40% or less (p less than 0.01). These findings indicate that atrial contribution to stroke volume is inversely related to left ventricular function.     

Role of echocardiography in patients with coronary artery disease.

Impaired left ventricular performance, one of the hallmarks of coronary artery disease, can be detected by echocardiography in various ways. One of these approaches is the recording of abnormal wall motion. Because of the way in which the left ventricle can be examined echocardiographically, this technique has the capability of detecting regional wall abnormalities. In fact echocardiography is probably the most sensitive technique available, including even contrast ventriculography, for the detection of akinetic, hypokinetic or dyskinetic wall segments. With increasing experience it is apparent that more areas of the left ventricle can be examined echocardiographically than had previously been thought possible. Newer techniques include directing the ultrasonic beam not only through the body of the left ventricle but also toward the apical portion of the ventricle near the vicinity of the papillary muscles. In addition the true anterior left ventricular wall can be examined by moving the transducer laterally away from the left sternal border. Yet another approach utilizes a subxiphoid position for the transducer while the ultrasonic beam is directed through the medial portion of the septum and posterolateral wall of the left ventricle. M-mode scanning techniques together with recently developed cross-sectional echocardiographic instruments give great promise of improved detection of abnormalities of ventricular shape, especially the presence of aneurysms. The cross-sectional approach makes it possible to examine the left ventricular apex, an area virtually impossible to record with M-mode echocardiography. Recording of left ventricular dimensions and abnormal mitral valve motion may help in assessing overall left ventricular performance. A dilated left ventricular dimension in the vicinity of the mitral valve seems to be an ominous finding both in patients with acute myocardial infarction and in patients with chronic coronary disease being considered for possible surgery. Another echocardiographic sign of abnormal ventricular performance is altered closure of the mitral valve, which reflects a significantly elevated left ventricular diastolic pressure. These echocardiographic techniques are still in the investigational stages and are more technically difficult than the usual echocardiographic applications. However, the preliminary data are encouraging and make us hopeful that echocardiography will prove to be an important tool in the overall evaluation of the left ventricle in patients with coronary artery disease.     

Real-time 3-dimensional echocardiography. Technique and clinical applications

This article will provide an overview of real time 3-dimensional (3D) echocardiography (RT-3D) in evaluation of patients with heart disease. We will briefly describe the technique and our experience in its clinical applications in patients with coronary artery disease, left ventricular apical thrombi, mitral stenosis and its role in guiding intracardiac catheter placement. Our extensive experience with application of RT-3D during dobutamine stress and during supine bicycle exercise indicates the technique is sensitive in detection of ischemia. RT-3D has been valuable in clearly identifying left ventricular apical thrombi in patients in whom 2-dimensional (2D) echo cannot firmly establish their presence or absence. We have utilized RT-3D in guiding myocardial biopsy in heart transplant patients and in precisely measuring mitral valve area before and after balloon valvuloplasty. RT-3D technique continues to evolve and should play an important role in assessment of patients with heart disease.     

Prediction of the extent of coronary artery disease with the evaluation of left ventricular wall motion abnormalities during atrial pacing. A cross-sectional echocardiographic study

In patients with coronary artery disease, left ventricular performance during stress is affected by the degree of coronary stenosis. In order to verify whether there exists a relationship between the extent of wall motion abnormalities detectable during atrial pacing and the degree of coronary obstruction, 76 patients, without previous myocardial infarction, were studied. Each patient underwent cross-sectional echocardiography during transesophageal atrial pacing and exercise electrocardiography before coronary angiography. Of the 76 patients, 46 had significant coronary artery disease (stenosis ⩾ 75% of at least one major coronary vessel), while 30 had normal coronaries or a stenosis of less than 75%. Eighteen patients had single-, 14 had two-and 14 had three-vessel disease. For each patient a coronary score was obtained: the score used took into consideration the site, number and severity of the stenosis. This score was then correlated with the wall motion score, obtained from the analysis of 9 segments of the left ventricle. A weak correlation was obtained between wall motion score at rest and coronary score (r = −0.42), while the correlation between coronary score and the difference between wall motion score at rest and during transesophageal atrial pacing was slightly better (r = 0.53); this correlation further improved if wall motion score during pacing was considered (r = −0.63). If the patients with discordant diagnostic tests (echocardiography during transesophageal atrial pacing and exercise electrocardiography) were excluded, the correlation coefficient between coronary score and wall motion score during pacing increased even more (r = −0.77).In conclusion: (1) analysis of wall motion of the left ventricle during atrial pacing is useful for the non-invasive evaluation of the severity of coronary disease; (2) cross-sectional echocardiography during atrial pacing, apart from being a useful diagnostic tool, is also a help in judging the degree of severity of coronary artery disease.     

Clinical uses of two dimensional echocardiography

The added advantages of two dimensional over M mode echocardiography in the diagnosis of cardiac disorders occurring in adults are reviewed. In patients with coronary artery disease, left ventricular aneurysm, wall motion abnormalities and ventricular dysfunction can be reliably evaluated with two dimensional echocardiography. Preliminary studies have demonstrated that two dimensional echocardiography is useful for assessing regional cardiac dilatation and prognosis after acute myocardial infarction, detecting left main coronary stenosis and predicting operability in patients with ventricular aneurysm. Determination of mitral valve area by two dimensional echocardiography in patients with mitral stenosis has shown good correlation with measurements of mitral valve area and size performed at the time of operation or calculated from cardiac catheterization data. The cause of mitral regurgitation can be more reliably elucidated by the differentiation of valvular and myocardial pathologic conditions. In addition, precise anatomic cardiac detail can be obtained in the localization of left and right ventricular and aortic outflow obstruction. Tricuspid valve disorders are particularly apparent because all three leaflets of the tricuspid valve can be visualized in real time studies and the detection of tricuspid regurgitation can be readily accomplished. Two dimensional echocardiography appears to be more reliable than M mode echocardiography in the detection of complications occurring as a result of bacterial endocarditis. Bioprosthetic valve function and localization and site of pericardial effusions as well as aortic aneurysms can be determined with two dimensional echocardiography. Two dimensional echocardiography can provide an accurate appreciation of the size, shape, mobility and origin of an intracardiac mass. With the use of contrast echocardiography, right to left shunting or the negative contrast effect can be demonstrated in patients with an atrial septal defect. Thus, the precision, accuracy and sensitivity of two dimensional echocardiography affords the clinician a valuable noninvasive instrument in the detection of cardiac disease.     

Catheter ablation of right ventricular outflow tract tachycardia: value of defining coronary anatomy

INTRODUCTION: Thermal damage to coronary arteries during catheter ablation has been previously reported. Coronary artery damage during LV outflow tract ventricular tachycardia is well recognized. However, the relationship of the coronary arteries to the RV outflow tract during catheter ablation has not been delineated. The purpose of this study was to define the relationship between the RV outflow tract and the coronary arteries utilizing arteriography, echocardiography, CT angiography, and gross anatomic pathology. METHODS: The relationship of the coronaries to the RV outflow tract was analyzed in three patients groups: Group 1: patients (n = 10) undergoing RV outflow tract ventricular tachycardia; Group 2: patients (n = 50) undergoing CT coronary angiography; Group 3: patients (n = 4) undergoing echocardiography during open heart surgery and intracardiac echocardiography (ICE) during catheter ablation of atrial fibrillation (n = 5). RESULTS: Group 1: The left main coronary artery was found to be 3.8 +/- 1.2 mm from the right ventricular outflow tract in patients undergoing ablation. Group 2: The minimum distance between the left main, left anterior descending, and right coronary artery to the RV outflow tract endocardial wall were 4.1 +/- 1.9 mm, 2.0 +/- 0.6 mm, and 4.3 +/- 1.9 mm (average +/- SD) respectively. Group 3: During open heart surgery using echocardiography, the minimum distance between the left main and the right coronary artery to the RV outflow tract were 3.4 +/- 0.35 mm and 2.0 +/- 0.1 mm, respectively. The distance between the let main coronary artery and the RVOT by ICE was 3.8 +/- 0.45 mm. CONCLUSIONS: The major coronary arteries lie in close proximity of the RVOT, and their anatomic course should be taken into consideration during ablation of ventricular tachycardias arising from the RV outflow tract.