Chau-Hsiung Chang

Predictors of Systemic Embolism in Patients with Mitral Stenosis: A Prospective Study

Systemic, especially cerebral, embolism is one of the major causes of illness and death in patients with mitral stenosis [1-5]. Identification of risk factors for embolism may improve the strategies for preventing this event. However, most large studies addressing risk predictors have been retrospective [1, 2, 6-9]. We sought to reappraise this issue in a large, prospective study. Methods Patients Eligible patients were consecutive adults (age 15 years) with mitral stenosis (mitral valve area 2 cm2 according to echocardiographic planimetry) who presented to a university-affiliated medical institution from April 1987 to December 1994. We excluded patients with infective endocarditis and those who were in critical condition because of systemic embolism and died during hospitalization. End Point The study end point was the occurrence of new systemic embolism during follow-up. The diagnosis of systemic embolism was based on symptoms and signs (sudden onset of peripheral arterial ischemic [for example, sudden flank pain with hematuria, abdominal pain with gastrointestinal bleeding, or leg pain with pulse deficit] or neurologic manifestations without prodromes) and on findings from computed tomography, angiography, and surgery. We did not attempt to detect silent emboli. Clinical Variables We assessed nine clinical variables (Table 1): age at enrollment; sex; presence or absence of previous systemic embolism, atrial fibrillation, hypertension, and New York Heart Association class III or IV congestive heart failure; and therapy with anticoagulants, percutaneous balloon mitral commissurotomy, or valvular surgery. Patients were regularly followed at outpatient clinics. Table 1. Clinical and Echocardiographic Variables in 534 Patients with Mitral Stenosis* Echocardiographic Method and Variables Standard transthoracic echocardiography was done at enrollment in all patients by using a Hewlett-Packard 7340, Sonos 1000, or Sonos 1500 echocardiographic system (Hewlett-Packard, Palo Alto, California) interfaced with both 2.5-MHz and 5.0-MHz transducers. Biplane or omniplane transesophageal echocardiography using a 5.0-MHz transducer was also performed in a subgroup of consecutive patients who entered the study from September 1991 to October 1992. Ten echocardiographic variables were examined (Table 1). Mitral valve area was measured by planimetry from two-dimensional echocardiography. When two-dimensional echocardiography of the mitral orifice yielded unsatisfactory results, we used the pressure half-time (T1/2) method (mitral valve area [cm2] = 220/T1/2 ms) [10-12]. We did not use the pressure half-time method when the mitral orifice could be clearly defined by two-dimensional echocardiography because pressure half-time is influenced by many factors other than mitral valve area [13, 14]. Other echocardiographic variables were left atrial diameter at end systole; presence or absence of a left atrial thrombus [15] or left atrial smoky echoes on transthoracic or transesophageal echocardiography [16-18]; presence or absence of impaired left ventricular systolic performance; and presence or absence of significant (moderate or severe) aortic stenosis, aortic regurgitation, mitral regurgitation, tricuspid regurgitation, or pulmonic regurgitation. The degrees of these valvular lesions were semiquantified by using a continuity equation (for aortic stenosis) or color Doppler imaging (for various regurgitations), as described elsewhere [19, 20]. Briefly, significant aortic stenosis refers to an aortic valve area of 1.2 cm2 or less determined by the continuity Equation method RF 19*; significant mitral or tricuspid regurgitation refers to a ratio of regurgitant jet area to left or right atrial area of 20% or more; and significant aortic or pulmonic regurgitation refers to a ratio of jet width to ventricular outflow tract diameter of 25% or more [20]. Left atrial diameter at end systole was measured from an M-mode echocardiogram recorded in parasternal long-axis view. The measurement was made according to the recommendations of the American Society of Echocardiography [21]. To detect left atrial smoky echoes, we used a 5-MHz transducer during transthoracic and transesophageal echocardiography because a 5-MHz transducer is more sensitive than a 2.5-MHz transducer [16]. We chose the term smoky echoes instead of spontaneous echocardiographic contrast (a term frequently used in other studies [6, 7]) because some patients with severe tricuspid regurgitation or right heart failure had bright moving spots (originating from microbubbles) in the venae cavae or hepatic veins that were identical to those seen during contrast echocardiography. Thus, we reserve spontaneous echocardiographic contrast for that echocardiographic pattern and use smoky echoes for the finer, lighter whorling echoes (originating from aggregated erythrocytes) [16-18] that appeared in the left atrium in patients with severe mitral stenosis. Statistical Analysis For each clinical and echocardiographic measure, the log-rank statistic was used to determine whether the overall pattern of the time to development of systemic embolism (embolism-free time) varied among levels of the measure. Mean embolism-free time was estimated by using a nonparametric method that considers censoring [22]. Cox regression was used to examine the significance of the clinical and echocardiographic variables in predicting embolism-free time for patients in sinus rhythm and patients in atrial fibrillation. All analyses were performed by using BMDP Dynamic Release 7.0 [23]. Results Five hundred thirty-four patients were followed for a mean (SD) of 36.9 22.5 months. Of these, 257 patients (48.1%) received anticoagulants throughout the follow-up period. The indications for anticoagulation were the presence of a left atrial thrombus, atrial fibrillation, or a history of systemic embolism; patient compliance with therapy; and lack of risk factors for bleeding. The relatively low percentage of patients receiving anticoagulants in this series was due to minimal patient compliance. During the follow-up period, 60 patients (11.2%) developed a systemic embolism. When Cox regression was performed, significant interaction was found between atrial fibrillation and age, percutaneous balloon mitral commissurotomy, mitral valve area, previous systemic embolism, left atrial thrombus, and anticoagulation. In other words, the significance of these variables depended to some extent on whether the patient was in atrial fibrillation or sinus rhythm. We therefore performed subgroup analyses. Subgroup Analyses Of the 132 patients in sinus rhythm, 12 (9.1%) developed systemic embolism during follow-up. Age (P < 0.001), percutaneous balloon mitral commissurotomy (P = 0.02), and mitral valve area (P = 0.02) were significant predictors in the log-rank analysis (Table 2). Results of the Cox regression showed that age (relative risk [RR], 1.12 [95% CI, 1.04 to 1.21]), left atrial thrombus (RR, 37.1 [CI, 2.82 to 487.8]), mitral valve area (RR, 16.9 [CI, 1.53 to 187.0]), and significant aortic regurgitation (RR, 22.4 [CI, 2.72 to 184.8]) were significant predictors of new systemic embolism (Table 3). No interactions were found among these variables. However, mitral valve area became a nonsignificant predictor (P = 0.12) when patients with percutaneous balloon mitral commissurotomy were excluded from the analysis. Table 2. Subgroup Univariate Analysis of Correlates of Systemic Embolism in Patients with Mitral Stenosis* Table 3. Cox Regression Analysis of Predictors of Systemic Embolism in Patients with Mitral Stenosis* Of the 402 patients in atrial fibrillation, 48 (11.9%) developed systemic embolism. Age (P = 0.01), previous embolism (P = 0.001), and percutaneous balloon mitral commissurotomy (P = 0.003) were significant predictors in the univariate analysis (Table 2). In the multivariate analysis, however, only previous embolism (RR, 3.11 [CI, 1.66 to 5.85]) and percutaneous balloon mitral commissurotomy (RR, 0.37 [CI, 0.18 to 0.79]) remained significant predictors of embolism-free time (Table 3). Again, no interactions were found between these two variables. A subgroup analysis of the 164 patients who underwent baseline transesophageal echocardiography revealed no other significant predictors. Discussion Factors Correlated with Systemic Embolization in Patients with Mitral Stenosis Our prospective study revealed that for patients in sinus rhythm, embolization was related to age, mitral valve area, the presence of a left atrial thrombus, and significant aortic regurgitation. For patients in atrial fibrillation, the significant factors were previous embolism and percutaneous balloon mitral commissurotomy (Table 3). Other retrospective studies have shown that atrial fibrillation [1, 2, 8], age [1, 2, 8], and previous embolism [3] correlate with increased incidence of systemic embolism in patients with mitral stenosis and that age is closely related to the prevalence of atrial fibrillation [24] and to a history of embolization [1, 2, 8]. Several studies have shown that anticoagulation reduces the incidence of systemic embolism in patients with mitral stenosis and atrial fibrillation [25-27]. To the best of our knowledge, however, our study is the first to show that the presence of a left atrial thrombus and significant aortic regurgitation are positive predictors and that percutaneous balloon mitral commissurotomy seems to be a negative predictor. Left Atrial Thrombus and Systemic Embolism in Patients with Mitral Stenosis Who Are in Sinus Rhythm Dislodgement of a left atrial thrombus in patients with mitral stenosis has been thought to lead to systemic embolism. Although a correlation between left atrial thrombus and systemic thrombus would be expected, previous studies have not confirmed such a correlation. We found that the presence of a left atrial thrombus was a positive predictor (RR, 37.1 [CI, 2.82 to 487.8]) for patients in sinus

Video-assisted mitral valve operations

BACKGROUND Video-assisted endoscopy has been applied frequently in the management of a variety of surgical diseases. However, it has rarely been applied in mitral valve surgery. METHODS We report 2 patients who received emergency operations for thrombosis of a mitral prosthesis (patient 1, a 68-year-old man) and acute mitral regurgitation due to rupture of anterior chordae (patient 2, a 75-year-old woman). They both had severe congestive heart failure. Cardiogenic shock was noted in patient 2. The mitral valve was approached through a right anterior minithoracotomy with the aid of an endoscope by means of projected images on the video monitor under femorofemoral cardiopulmonary bypass. The aorta was not cross-clamped, and the myocardium was protected by continuous coronary perfusion with hypothermic fibrillatory arrest. The left atrium was entered posterior to the interatrial groove. Thrombectomy and mitral valve repair were performed successfully. RESULTS The duration of extracorporeal circulation was 204 and 147 minutes, respectively. Both patients recovered from the operation rapidly with uneventful postoperative courses. CONCLUSIONS Our preliminary results suggest that video-assisted endoscopic cardiac surgery is technically feasible and could be performed in the milieu of open heart surgery.

Thoracoscopic management of effusive pericardial disease: Indications and technique

Video-assisted thoracoscopic technique was evaluated in 28 patients who underwent operation for massive pericardial effusion. Excellent results were obtained using this newly developed approach for inspection of all pericardial surfaces as well as pleural and pulmonary disorders. No perioperative or postoperative complications ensued. Videothoracoscopy revealed positive lung malignancies in 11 patients, and these would not have been promptly diagnosed without thoracoscopy. Thoracoscopy also confirmed metastatic deposits on the pleura and diaphragm in 4 other patients. The visible nodules were proved to be metastatic adenocarcinoma. In 13 patients, thoracoscopy did not reveal malignancy, although 2 of these patients had a clinically suspected malignant lung tumor. Other indications for thoracoscopic drainage included 2 patients with impending pericardial tamponade after heart procedures and 6 patients with recurrent/loculated pericardial effusion. All of the patients showed promising and favorable postoperative courses after thoracoscopy. From our experience, video-assisted thoracoscopy was a safe and effective procedure, especially for those patients with combined pericardial effusion and abnormal pulmonary or pleural pathology in whom subxiphoid pericardial window was not clearly diagnostic at the time of operation. It was effective also in the situation with recurrent or loculated pericardial effusion which allowed localization and drainage of it. We believe that the use of videothoracoscopy to visualize the whole pericardial and pleural cavity will continue to be of great benefit to patients with combined pericardial and pleural/lung diseases.

Thoracoscopic Removal of Intrathoracic Neurogenic Tumors: A Combined Chinese Experience

ObjectiveTo review the surgical and clinical results of minimally invasive resection of intrathoracic neurogenic tumors using a video-assisted thoracoscopic technique. Summary Background DataThoracoscopy has emerged as a possible means for diagnosing and managing various intrathoracic disorders. Benign intrathoracic tumors often are ideal lesions for resection using a video-assisted technique. The authors report on their combined experience with the thoracoscopic resection of 143 intrathoracic neurogenic tumors. MethodsBetween March 1992 and February 1999, 143 patients with intrathoracic neurogenic tumors were diagnosed and underwent resection using video-assisted thoracoscopic techniques in three teaching centers. Case selection, surgical technique, and clinical results were reviewed. ResultsThe average age of the patients was 40.8 years; 57.3% were male. Thirty-eight patients (27%) had symptoms attributable to the masses. Seventy-two masses were neurofibromas, 33 were neurilemmomas, 7 were paragangliomas, and 31 were ganglioneuromas. All but seven tumors were located in the posterior mediastinum. The masses were on average 3.5 cm in greatest diameter. The mean surgical time was 40 minutes, and the average hospital stay was 4.1 days. There were no major postoperative complications or recurrences to date. Nine patients reported paresthesias over the chest wall during a mean follow-up of 29 months. ConclusionsResection of intrathoracic neurogenic tumors using a thoracoscopic technique based on standard surgical indications would seem to be appropriate. Most of these masses are benign and readily removed. For dumbbell tumors, a combined thoracic and neurosurgical approach is mandatory.

Thoracoscopic Surgery for Spontaneous Pneumothorax

Abstract. Spontaneous pneumothorax in apparently healthy individuals is a relatively common occurrence. The management of patients with spontaneous pneumothorax remains controversial. With the advances in thoracoscopic techniques and instrumentation, video-assisted thoracic surgery (VATS) is now accepted by many as the procedure of choice for surgical treatment of spontaneous pneumothorax. We report our combined experience with 757 patients who suffered from recurrent or persistent spontaneous pneumothorax treated by VATS over a 5-year period. Surgical indications included persistent air leak (n= 165), recurrence (n= 325), radiologically demonstrated huge bulla (n= 12), spontaneous hemopneumothorax (n= 13), incomplete expansion of the lung (n= 212), and bilateral involvement (n= 30). Several surgical procedures were undertaken, based on the thoracoscopic findings: endoscopic stapled bullectomy (n= 312), argon beam coagulation (n= 6), endoscopic suturing (n= 52), and endoloop ligation (n= 352). In 49 cases, mechanical or chemical pleurodesis was the only procedure performed. There were no mortalities or intraoperative hazards. Complications consisted of wound infections (n= 16), localized empyema (n= 2), chest wall bleeding (n= 1), and persistent air leaks (bulla type III) (n= 31). The median duration of the operation was 55 minutes (15–160 minutes), and the average postoperative hospital stay was 4.5 days (range 0–27 days). There were 16 recurrences (2.1%), after a mean follow-up of 30 months (range 1–60 months). Seven patients had recurrence from 9 to 17 months after stapled bullectomy. All the remaining patients had recurrence after failed pleurodesis. On the basis of our results, we conclude that video-assisted thoracoscopic management allows effective, safe performance of standard surgical procedures, avoiding a formal thoracotomy incision. We consider thoracoscopy the treatment of choice for patients with pneumothorax requiring surgical therapy.

Video-assisted thoracic surgery in treatment of chest trauma.

Although the indications for video-assisted thoracic surgery (VATS) have expanded rapidly, especially in the areas of therapeutic and operative procedures, its role in the definite surgical treatment of chest trauma is not clear. From July 1994 to December 1995, 56 patients with hemothorax or posthemothorax complications resulting from chest trauma received thoracic surgery. Their ages ranged from 17 to 71 years. Mechanisms of injury included penetrating (n = 23) and blunt injury (n = 33). VATS was successfully applied in 50 patients; six patients with cardiovascular injuries (n = 4) or minor chest wall lacerations (n = 2) did not receive VATS. All patients who received VATS survived, with no morbidity. Twelve of the 50 patients treated with VATS would have otherwise had to undergo thoracotomy. Our results indicate that VATS can be safely used in hemodynamically stable patients with no cardiovascular or great vessel injury, sparing many patients the pain and morbidity associated with thoracotomy. Additionally, use of VATS may reduce the likelihood of posthemothorax complications by allowing early direct inspection of the chest wall, because VATS has a lower associated risk and can be performed with a lower index of suspicion than can standard thoracotomy.

Minimally Invasive Cardiac Surgical Techniques in the Closure of Ventricular Septal Defect: An Alternative Approach

BACKGROUND Minimally invasive cardiac surgical techniques recently have been applied in the management of a variety of intracardiac lesions. METHODS Fourteen patients (6 boys and 8 girls; age, 8.9 +/- 5.5 years; body weight, 29.0 +/- 13.5 kg) were operated on using minimally invasive cardiac surgical techniques for the closure of a ventricular septal defect (subarterial in 11 patients and perimembranous in 3 patients). The operations were performed through a left anterior minithoracotomy and were guided by video-assisted endoscopic techniques under femorofemoral cardiopulmonary bypass. The myocardium was protected by continuous coronary perfusion with hypothermic fibrillatory arrest. The right ventricular outflow tract was entered after pericardiotomy was performed. RESULTS Closure of the defect (directly in 4 patients and by patch in 10 patients) was performed successfully in all patients. A right ventricular outflow tract obstruction and ruptured sinus of Valsalva aneurysm also were repaired in 1 patient each. The duration of cardiopulmonary bypass was 41 +/- 10 minutes (range, 28 to 100 minutes) and the total operative time was 2.2 +/- 0.8 hours (range, 1.3 to 3.5 hours). All the patients recovered rapidly from their operation and had an uneventful postoperative course. Follow-up (mean, 6.2 months; range, 6 to 9 months) was complete in all patients. There were no late deaths. Transthoracic echocardiographic examination showed no residual shunt and no aortic regurgitation in all patients. CONCLUSIONS Our experience demonstrates that minimally invasive cardiac surgical techniques are technically feasible and an alternative option for the repair of a ventricular septal defect.

Pulmonary artery perforation after Kirschner wire migration : case report and review of the literature

Utilization of Kirschner wires for bone and joint fixation is potentially complicated by migration of the wire from the fixation site over time. However, a review of the literature disclosed few reports of this complication. We describe such a case in order to emphasize the potential danger of the migration of such metallic devices used near thoracic cavity.

Doppler and two-dimensional echocardiographic features of sinus of Valsalva aneurysm

Doppler, contrast, and two-dimensional echocardiograms of 12 aneurysms of the sinus of Valsalva in 10 consecutive patients were analyzed in order to highlight the diagnostic features. The diagnosis were confirmed by surgical and/or catheterization findings. The aneurysms had ruptured in 7 of 12 (58%). Two-dimensional echocardiography prior to the contrast studies was able to delineate the aneurysms in 7 of 12 (58%). The contrast studies outlined two additional aneurysms. The right aneurysms directed anteriorly and caudally. The noncoronary aneurysms formed an extraneous lumen at the posterior part of the aortic root, mimicking aortic dissection. Doppler examinations showed systolic and diastolic turbulence in five of six (83%) of the right aneurysms rupturing into the right ventricular outflow tract. Color Doppler echocardiography showed a left ventricular diastolic turbulence emanating from the aneurysm in a case with a noncoronary aneurysm rupturing into the left ventricle. It is concluded that the principal Doppler, contrast, and two-dimensional echocardiographic features usually allow a rapid correct diagnosis of sinus of Valsalva aneurysm.

Protection of the brain by retrograde cerebral perfusion during circulatory arrest

Hypothermic circulatory arrest is commonly used to facilitate repair of complex congenital heart defects and aortic lesions and for complex neurosurgical procedures. However, extended periods of circulatory arrest may impair cerebral metabolism and cause ischemic injury. Retrograde cerebral perfusion has been applied recently in aortic surgery to protect the brain. From January 1991 to December 1993, 29 patients underwent emergency operations to repair acute type A aortic dissection with the aid of hypothermic circulatory arrest. Six patients received hypothermic circulatory arrest without retrograde cerebral perfusion with a rectal temperature of 16.4 degrees +/- 0.9 degrees C (mean +/- standard error of the mean, group 1). Retrograde cerebral perfusion during hypothermic circulatory arrest was performed in 15 patients with a rectal temperature of 15.9 degrees +/- 0.5 degrees C (group 2) and in eight patients with a rectal temperature of 21.7 degrees +/- 0.8 degrees C (group 3). The hypothermic circulatory arrest times were 25 +/- 4, 42 +/- 4, and 63 +/- 6 minutes, respectively (p < 0.05). The cardiopulmonary bypass times were 173 +/- 5, 184 +/- 7, and 143 +/- 6 minutes, respectively (p < 0.05). All patients survived the operation and regained consciousness with no neurologic defects. Follow-up (mean 23.2, 14.5, and 5.1 months, respectively) was complete in all patients except one. This patient, from group 2, was killed in a road traffic accident 12 months after the operation. Our experience suggests that retrograde cerebral perfusion can effectively protect the brain from ischemic injury and extend the safe period of hypothermic circulatory arrest. With the aid of retrograde cerebral perfusion, prolonged circulatory arrest can probably be performed safely with moderate hypothermia.