Transesophageal echocardiography for study of bioprostheses in the aortic valve position.
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Aged↗
Biomedical subjects
I Schnittger
Publications and source records attributed to I Schnittger.
Aspects of mechanical ventilation affecting interatrial shunt flow during general anesthesia.
Intraoperative transesophageal echocardiography was used to study the incidence of flow-patent foramen ovale in 33 normal, healthy patients (ASA physical status I) undergoing general anesthesia in the supine position for nonthoracic surgical procedures. Echocardiographic contrast was injected intravenously during mechanical ventilation in the presence of 0, 5, 10, 15, or 19 cm H2O positive end-expiratory pressure (PEEP). A final test was performed during the release of 19 cm H2O PEEP. The presence of a flow-patent foramen ovale was detected when the injected echo targets were observed crossing the interatrial septum from right to left. Most interesting, 3 of 33 patients developed a right-to-left shunt that was first detected with the steady application of 10 (1 patient) or 15 cm H2O PEEP (2 patients). In all three cases, the shunt flow was accentuated on the release of PEEP; however, no additional cases were detected using this respiratory maneuver. These cases represent the first demonstration of right-to-left interatrial shunting evoked as the result of the sustained application of PEEP. This study also revealed a lower than expected incidence of flow-patent foramen ovale (9%) when measured during general anesthesia and positive pressure ventilation with or without PEEP.
Adult↗
Frequency and mechanism of bradycardia in cardiac transplant recipients and need for pacemakers.
Orthotopic cardiac transplantation is occasionally complicated by unexplained bradyarrhythmias. Sinus node injury as a consequence of operation or acute rejection has anecdotally been linked to the development of bradycardia early after transplantation. These arrhythmias are empirically managed by pacemaker implantation, the indications for which remain poorly defined. This retrospective study examined the 20-year experience of our institution with bradyarrhythmias after transplantation to determine the predisposing factors and indications for pacemaker implantation. Forty-one of 556 patients in our cardiac transplant program (7.4%) received permanent pacemakers between 1969 and 1989. The predominant rhythm disturbances were junctional rhythm (46%), sinus arrest (27%) and sinus bradycardia (17%). Most patients were asymptomatic (61%), and presented in the early post-transplant period (73%). Four possible predisposing factors were evaluated: (1) graft ischemic time, (2) rejection history, (3) use of bradycardia-inducing drugs, and (4) anatomy of blood supply to the sinoatrial (SA) node. No significant differences existed between patients with and without pacemakers with regard to the first 3 variables. However, after transplantation angiograms showed that prevalence of abnormal SA nodal arteries was greater in patients with than without pacemakers (p less than 0.02). Pacemaker follow-up at 3, 6 and 12 months showed persistent bradycardia (60 to 90 beats/min) in 88, 75 and 50% of patients, respectively. The most common pacemaker complication (15%) was lead displacement at time of biopsy. These results suggest that disruption of the SA nodal blood supply may be an important predisposing factor in the development of bradycardias.
Adolescent↗
Hepatic venous flow assessed by transesophageal echocardiography.
Systemic venous flow patterns are easily assessed by transthoracic echocardiography for evaluation of right heart dynamics. However, the transthoracic approach cannot be used in patients undergoing thoracic surgery. The present study describes a method for obtaining hepatic venous flow velocity with transesophageal Doppler echocardiography. Twenty-nine patients were studied with transthoracic echocardiography just before cardiac surgery and with transesophageal echocardiography during surgery. Hepatic venous flow velocity recordings were obtained in 14 of 29 patients with the transthoracic and in all 29 with the transesophageal approach. Timing of flow pattern was similar with the two methods, but recordings obtained with transesophageal echocardiography were inverted compared with those obtained with transthoracic echocardiography as a result of the difference in probe location in relation to flow direction. The time-velocity integrals obtained with the two techniques did not differ significantly; for the transthoracic and transesophageal approaches, they were, respectively, 7.3 +/- 3.4 versus 5.7 +/- 4.4 for systolic flow; 1.0 +/- 1.0 versus 0.5 +/- 0.6 for end-systolic flow reversal; 4.7 +/- 2.3 versus 3.7 +/- 1.7 for diastolic flow; 2.0 +/- 1.8 versus 1.5 +/- 1.5 for atrial flow reversal and 1.9 +/- 1.0 versus 1.7 +/- 1.1 for systolic/diastolic ratio. In conclusion, hepatic venous flow values are obtained more frequently and with better quality by transesophageal than by transthoracic echocardiography. The flow patterns and velocity integrals are similar with both methods and previous experience with transthoracic echocardiography should be applicable to the transesophageal technique. Transesophageal Doppler echocardiography therefore has potential for studying right heart dynamics during anesthesia and surgery.
Anesthesia, General↗
Intraoperative ventilator-induced right-to-left intracardiac shunt.
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Anesthesia, General↗
Enhanced detection of intracardiac sources of cerebral emboli by transesophageal echocardiography.
We performed transesophageal echocardiography in 50 consecutive hospitalized patients with recent transient ischemic attack or stroke of embolic origin to determine whether transesophageal echocardiography is more sensitive than transthoracic echocardiography in detection of possible intracardiac sources of embolism. Twenty-six of 50 patients with a negative transthoracic echocardiogram for potential source of emboli had a transesophageal echocardiography study that demonstrated at least one intracardiac abnormality. Abnormalities noted by transesophageal echocardiography included five of 50 patients with either a left atrial or left atrial appendage clot, four patients with a patent foramen ovale, and nine patients with spontaneous echocardiographic contrast. In 11 of 50 patients with no other source of embolism, we found highly mobile filamentous strands on the mitral valve, which have not been described previously. These mitral valve echo strands may represent a fissured surface or fibrosis that can serve as a nidus for thrombus formation. We detected no unexpected left ventricular thrombus or left atrial myxoma. Factors significantly associated with a greater likelihood of a positive transesophageal echocardiography study included left atrial enlargement, atrial fibrillation, and a calcified or thickened mitral valve. Our study suggests that transesophageal echocardiography is a valuable addition to transthoracic echocardiography in investigating potential intracardiac sources of embolism.
Cerebral Infarction↗
Leftward shift of the interventricular septum and pulsus paradoxus in obstructive sleep apnea syndrome.
Echocardiograms were taken from the parasternal long axis view during nocturnal sleep in ten patients diagnosed with OSAS. A table designed to support the echocardiographic probe prevented significant sleep disturbances during monitoring and allowed continuous data collection with and without nasal CPAP administration. In five of ten patients, there was before CPAP treatment a diastolic LSIVS during NREM sleep, inducing a flattening of the left ventricle. Arterial blood pressure recordings showed pulsus paradoxus when LSIVS was occurring. Nasal CPAP led to normal, unobstructed breathing, significant decrease in Pes nadir and disappearance of LSIVS and pulsus paradoxus. Increase in left ventricular afterload and increase in total peripheral resistance could lead to hypertrophy and hypertension in some OSAS patients. The presence of pulsus paradoxus in OSAS indicates a marked increase in Pes nadir, and its disappearance with nasal CPAP may be one of the signs of effective treatment of OSAS.
Adult↗
Serial measurement of integrated ultrasonic backscatter in human cardiac allografts for the recognition of acute rejection.
Cyclic variation of integrated ultrasonic backscatter (IB) was noninvasively measured in the septum and left ventricular posterior wall using a quantitative IB imaging system to assess the alterations in the acoustic properties of myocardium associated with acute cardiac allograft rejection. The study population consisted of 23 cardiac allograft recipients and 18 normal subjects. In each cardiac allograft recipient, one to eight (mean, four) IB studies were performed, each within 24 hours of right ventricular endomyocardial biopsy performed for rejection surveillance. The magnitude of the cyclic variation of IB in the posterior wall was 5.9 +/- 0.9 dB in normal subjects and 6.2 +/- 1.3 dB in the cardiac allograft recipients without previous or current histological evidence of acute rejection (n = 17, p = NS vs. normal subjects). The magnitude of cyclic variation of IB in the septum was 4.8 +/- 1.1 dB in normal subjects and 3.8 +/- 2.0 dB in the cardiac allograft recipients (n = 15, p = NS vs. normal subjects). A significant decrease in the septal IB measure was observed in cardiac allograft recipients with left ventricular hypertrophy (wall thickness of at least 13 mm) (2.6 +/- 1.7 dB, n = 8, p less than 0.05 vs. normal subjects). IB studies were done before and during moderate acute rejection in 11 recipients (14 episodes). During moderate acute cardiac rejection, the magnitude of the cyclic variation in IB decreased from 6.7 +/- 1.3 to 5.1 +/- 1.4 dB in the posterior wall (n = 14, p less than 0.05) and from 4.2 +/- 2.1 dB to 2.9 +/- 1.8 dB in the septum (n = 12, p less than 0.05). These data suggest 1) the magnitude of the cyclic variation in IB of the septum is different in cardiac allografts with cardiac hypertrophy and normal subjects, possibly reflecting regionally depressed myocardial contractile performance and 2) acute cardiac rejection in humans is accompanied by an alteration in the acoustic properties of the myocardium. This change is detectable by serial measurement of the magnitude of the cyclic variation in IB, both in the septum and in the posterior wall.
Echocardiography↗
Left ventricular diastolic function. Doppler echocardiographic changes soon after cardiac transplantation.
In acute cardiac rejection, left ventricular diastolic function is altered, and a restrictive ventricular filling pattern occurs. Doppler echocardiographic indexes of mitral inflow have been proposed as sensitive markers of the rejection process. As rejection progresses, the restrictive ventricular filling pattern is reflected by a shortening of isovolumic relaxation time and mitral valve pressure half-time and by an increase in early transmitral filling velocity. Diastolic function is also compromised in the nonrejecting cardiac transplant recipient during the early postoperative period. This study examined the progression in Doppler-derived mitral filling indexes in 25 recent cardiac transplant recipients who demonstrated no histological evidence of transplant rejection. Isovolumic relaxation time, mitral valve pressure half-time, and early transmitral filling velocity were measured at postoperative weeks 1, 2, 4, and 6 on the day that surveillance right ventricular endomyocardial biopsies were performed. The initial indexes were comparable to previously described restrictive parameters and over the 6-week study period evolved into a nonrestrictive filling pattern. This evolution reflects a progressive improvement in postoperative diastolic function and a decrease in left heart filling pressures. None of the evaluated clinical characteristics, including preoperative pulmonary pressures, total ischemic time of the transplanted heart, cardiopulmonary bypass time, and age of the donor heart, correlated with this process. Given the increasing use of Doppler echocardiography as a means of screening for transplant rejection, it is important to have a thorough understanding of normal postoperative changes in left ventricular diastolic function.
Adult↗
Ultrasonic tissue characterization with a real time integrated backscatter imaging system in normal and aging human hearts.
Experimental studies have shown that variation in the magnitude of integrated ultrasonic backscatter during the cardiac cycle represents acoustic properties of myocardium that are affected by pathologic processes; however, there are few clinical studies using integrated backscatter. Forty subjects without cardiovascular disease (aged 22 to 71 years, mean 41) were studied with use of a new M-mode format integrated backscatter imaging system to characterize the range of cyclic variation of integrated backscatter in normal subjects. Cyclic variation in integrated backscatter was noted in both the septum and the posterior wall in all subjects. The magnitude of the cyclic variation of integrated backscatter and the interval from the onset of the QRS wave of the electrocardiogram to the minimal integrated backscatter value were measured using an area of interest of variable size for integrated backscatter sampling and a software resident in the ultrasound scanner. The magnitude of cyclic variation was larger for the posterior wall than for the septum (6.3 +/- 0.8 versus 4.9 +/- 1.3 dB, p less than 0.01). The interval to the minimal integrated backscatter value was 328 +/- 58 ms for the septum and 348 +/- 42 ms for the posterior wall (p = NS). There was a weak correlation between the magnitude of cyclic variation of integrated backscatter and subject age for the posterior wall (r = -0.47, p less than 0.01), but this was not significant for the septum (r = -0.21) (partially because of inability to exclude specular septal echoes) and septal endocardium.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Long-term results of antitachycardia pacing in patients with supraventricular tachycardia.
Between 1979 and 1984 the Cybertach-60, (Intermedics, Inc. Model 262-01), a programmable, automatic antitachycardia pacemaker was implanted in 11 patients who had drug-refractory supraventricular tachycardia (SVT). The patients have been followed for a total of 64-108 (mean 84 months). All patients were symptomatic and had failed two or more drugs and six patients had required prior DC cardioversion. The mechanism of supraventricular tachycardia was atrioventricular (AV) nodal reentry in six patients, AV reentry in four patients, and atrial tachycardia in one patient. Preoperatively all patients had reliable termination of the tachycardia without induction of atrial fibrillation by pacing methods available to Cybertach-60. Postimplant, Cybertach-60 reliably terminated all episodes of tachycardia without ancillary drug therapy. Nevertheless, at long-term follow-up antitachycardia pacing was effective and safe in the minority (36%), with only four patients out of eleven still using a pacemaker for supraventricular tachycardia. One of these four patients required additional drug therapy. In one of the patients, the Cybertach-60 was replaced after 78 months by a more advanced device, (Intertach, Intermedics, Inc.) because of a depleted Cybertach-60 battery. In seven patients who no longer use antitachycardia pacing for termination of tachycardia, one patient developed atrial fibrillation during tachycardia termination (at 58 months postimplant). Three patients experienced induction of tachycardia or atrial fibrillation by the pacemaker due to undersensing of sinus P waves (at 36, 48, and 51 months).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Ultrasonic tissue characterization of human hypertrophied hearts in vivo with cardiac cycle-dependent variation in integrated backscatter.
Integrated ultrasonic backscatter (IB) is a noninvasive measure of the acoustic properties of myocardium. Previous experimental studies have indicated that altered acoustic properties of the myocardium are reflected by the magnitude of variation of IB during the cardiac cycle. In our study, cardiac cycle-dependent variation of IB was noninvasively measured using a quantitative IB imaging system in 12 patients with uncomplicated pressure-overload hypertrophy and 13 patients with hypertrophic cardiomyopathy. Sixteen normal subjects served as a control. The magnitude of cardiac cycle-dependent variation of IB for the posterior wall was 6.0 +/- 0.9 dB in normal subjects, 5.7 +/- 0.8 dB in the patients with uncomplicated pressure-overload hypertrophy, and 6.7 +/- 2.1 dB in the patients with hypertrophic cardiomyopathy. There were no significant differences among any of these groups. In contrast, the magnitude of cardiac cycle-dependent variation of IB for the septum was significantly smaller in the patients with uncomplicated pressure-overload hypertrophy (2.8 +/- 1.3 dB) and in the patients with hypertrophic cardiomyopathy (3.1 +/- 2.3 dB) than in normal subjects (4.9 +/- 1.0 dB). The magnitude of cardiac cycle-dependent variation of IB was smaller as the wall-thickness index increased (r = -0.53, p less than 0.01, n = 82 for all data). This IB measure also correlated with percent-systolic thickening of the myocardium (r = 0.67, p less than 0.01, n = 82). Thus, alteration in the magnitude of cardiac cycle-dependent variation of IB was observed in hypertrophic hearts and showed apparent regional myocardial differences.
Adult↗
Diastolic mitral and tricuspid regurgitation by Doppler echocardiography in patients with atrioventricular block: new insight into the mechanism of atrioventricular valve closure.
The purpose of this study was to prospectively determine the incidence of diastolic mitral and tricuspid regurgitation in atrioventricular (AV) block using Doppler echocardiography. The temporal relation between mitral and tricuspid diastolic insufficiency and the diastolic murmur recorded in patients with complete heart block was also investigated. Twenty-two consecutive patients with AV block (referred to the Echo-Doppler laboratory for routine clinical studies), aged 18 to 87 years, were enrolled in the study. Eleven patients had third degree AV block and a ventricular-inhibited (VVI) pacemaker, two patients had second degree AV block, seven patients had first degree AV block, one patient had blocked premature atrial complexes and one patient had atrial flutter with 4:1 AV block. Diastolic mitral regurgitation was detected in 20 patients, and diastolic tricuspid regurgitation in 21. A mid-diastolic murmur was detected in all patients except in the three youngest. The murmur occurred before diastolic regurgitation and coincided with peak forward flow through the AV valve after atrial contraction. M-mode mitral valve echocardiograms obtained in nine patients demonstrated near closure of some portions of the mitral valve after atrial contraction. Effective closure of the valve, however, did not occur unless ventricular systole supervened. In conclusion, diastolic mitral and tricuspid regurgitation are almost universally present in patients with AV block and are associated with a diastolic murmur. The murmur coincides with forward AV valve flow. Diastolic regurgitation is silent. Effective AV valve closure is not established until ventricular systole occurs, as demonstrated by M-mode echocardiographic recording of the mitral valve.
Adult↗
Transesophageal Doppler echocardiography.
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Aortic Diseases↗
Transesophageal two-dimensional echocardiography and color Doppler flow velocity mapping in the evaluation of cardiac valve prostheses.
To determine the value of transesophageal ultrasound in the assessment of cardiac valve prostheses, 14 patients with clinically suspected mitral prosthesis malfunction were studied by transthoracic and transesophageal two-dimensional imaging as well as by color Doppler flow velocity mapping (color Doppler). Patients underwent left ventricular angiography (n = 13), surgery (n = 11), or both angiography and surgery (n = 10). Nine patients had only mitral valve replacement, four patients had both mitral and aortic valve replacement, and one patient had mitral, aortic, and tricuspid valve replacement. There were 16 biological and four mechanical prostheses. The degree of mitral regurgitation was graded by both transthoracic and transesophageal color Doppler according to the area of the regurgitant jet visualized and was compared with a three-point classification of mitral regurgitation by left ventricular angiography judged by observers blinded to the echocardiographic results. All transesophageal studies were performed without complication and were well tolerated. The pathological morphology of the mitral prosthesis was additionally or more clearly visualized by transesophageal two-dimensional imaging and subsequently proven at surgery in three patients with flail leaflets and one patient with a vegetation compared with images obtained by the transthoracic approach. Valvular regurgitation was graded by the transthoracic approach as absent in four patients, mild in two patients, moderate in five patients, and severe in only three patients. The transesophageal assessment showed absence of mitral regurgitation in two patients, moderate regurgitation in two patients, and severe regurgitation in 10 patients.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Diagnostic challenges following cardiac transplantation.
It is now almost two decades since the first human cardiac transplantation was performed. Recipients will require close follow-up by their referring physicians outside of the main referral centers. This article is intended to assist the referring physician in choosing the most appropriate diagnostic studies throughout the posttransplant period.
Biopsy↗
Esophageal electrocardiography: a new technology revives an old technique.
This study evaluates the clinical use of an easily swallowed bipolar electrode for recording an esophageal electrocardiogram (ECG). Fourteen patients were selected for bedside diagnosis (ECG group) because of arrhythmias difficult to evaluate using a standard 12-lead ECG. A second group of 27 non-selected patients scheduled for routine 24-hour ambulatory electrocardiographic recordings (ambulatory ECG group) had an esophageal ECG recorded as the "third channel." All 14 patients (100%) in the ECG group had excellent-quality tracings, and the esophageal ECG was diagnostic in 12 cases (86%). Of 27 patients in the ambulatory ECG group, 19 (70%) had fairly good to excellent-quality 24-hour esophageal pill tracings, with the esophageal ECG contributing to correct arrhythmia diagnosis in 11 patients (41%). It is concluded that this easily swallowed esophageal electrode provides an excellent-quality short-term ECG and often permits proper arrhythmia diagnosis in selected patients with arrhythmias. Good-quality 24-hour esophageal ambulatory electrocardiographic recordings can also be obtained that contribute to arrhythmia diagnosis in a limited number of unselected patients, and should be even more clinically useful in carefully selected patients.
Arrhythmias, Cardiac↗
Timing of abnormal interventricular septal motion after cardiopulmonary bypass operations. Lack of injury proved by preoperative, intraoperative, and postoperative echocardiography.
Abnormal interventricular septal motion after cardiopulmonary bypass is a widely known occurrence. The cause and exact timing of this phenomenon remain unclear. We have studied 21 patients prospectively with preoperative, intraoperative, and postoperative two-dimensional and M-mode echocardiograms. Intraoperative studies were obtained with the pericardium closed and open and after completion of procedures performed with cardiopulmonary bypass. Fourteen patients had coronary artery bypass graft operations alone. Six patients had valve replacement with or without coronary bypass, and one patient had removal of a left atrial myxoma. All patients had normal interventricular septal motion before the operation, and none had abnormal septal motion intraoperatively. Four to eight days postoperatively, the septum still thickened normally in all patients, with five patients having normal, nine patients abnormal, and seven patients paradoxical interventricular septal motion. Studies in 11 patients 1 to 4 months postoperatively showed no change from the early postoperative study. The pericardium was left open postoperatively in all patients. Six patients were studied a few hours after sternal closure and all had abnormal interventricular septal motion. We conclude that abnormal interventricular septal motion after cardiac operations is not due to injury of the septum, adhesion formation, or loss of pericardial constraint. Closure of the chest wall itself, with the pericardium left open, is associated with this abnormality.
Cardiomyopathies↗