Predictability of aortic dissection as a function of aortic diameter

The role of aortic diameter on the occurrence of type A dissectionwas investigated in 73 patients with dilated ascending aortaat the lime of pre-operative evaluation. Using transthoracicechocardiography for diagnosis and measurements, 54 patientswere identified with type A dissection (group 1) and 19 withoutdissection (group 2). The true mean aortic diameters were identical(6·0±1·3 cm in group 1 and 6·4±1·4cm in group 2; mean±SD; ns) as were the indexed aorticdiameters (ratio of diameter/body surface area; 3·2±0·8cm . m^–12 and 3·4±0·7cm m^–2respectively; ns). However, the individual diameters showeda pronounced scatter in both groups (range from 3·6±11·0cm). Of the 73 patients, 66 had surgery (47/54 with and 19/19without dissection) and seven patients were treated medically.Emergency surgery was performed in 45/66 patients (all withacute type A dissection) andelective repair in 21/66 (19 withoutand two with chronic type A dissection). In-hospital mortalitywas 18% in the emergency group, 5% in the elective group and57% in the medical group. It is concluded that patients with dilated ascending aorta havea substantial incidence of acute dissection. Their clinicalcourse is unpredictable; acute dissection occurs in some, andin others the ascending aorta continues to enlarge without dissection.Because patients with dissection often arrive too late for electiverepair andhave to be operated on as emergencies with a higheroperative risk, we recommend elective surgery before the diameterof the ascending aorta has reached 6 cm.     

Predictability of aortic dissection as a function of aortic diameter.

The role of aortic diameter on the occurrence of type A dissection was investigated in 73 patients with dilated ascending aorta at the time of pre-operative evaluation. Using transthoracic echocardiography for diagnosis and measurements, 54 patients were identified with type A dissection (group 1) and 19 without dissection (group 2). The true mean aortic diameters were identical (6.0 +/- 1.3 cm in group 1 and 6.4 +/- 1.4 cm in group 2; mean +/- SD; ns) as were the indexed aortic diameters (ratio of diameter/body surface area; 3.2 +/- 0.8 cm.m-2 and 3.4 +/- 0.7 cm.m-2, respectively; ns). However, the individual diameters showed a pronounced scatter in both groups (range from 3.6 +/- 11.0 cm). Of the 73 patients, 66 had surgery (47/54 with and 19/19 without dissection) and seven patients were treated medically. Emergency surgery was performed in 45/66 patients (all with acute type A dissection) and elective repair in 21/66 (19 without and two with chronic type A dissection). In-hospital mortality was 18% in the emergency group, 5% in the elective group and 57% in the medical group. It is concluded that patients with dilated ascending aorta have a substantial incidence of acute dissection. Their clinical course is unpredictable: acute dissection occurs in some, and in others the ascending aorta continues to enlarge without dissection. Because patients with dissection often arrive too late for elective repair and have to be operated on as emergencies with a higher operative risk, we recommend elective surgery before the diameter of the ascending aorta has reached 6 cm.     

Aorta and aortic valve morphologies predisposing to aortic dissection: An in vivo assessment with ransoesophageal echocardiography

Predisposing factors for aortic dissection are well known fromnecropsy series. To evaluate the frequency of aortic and aorticvalve disease in aortic dissection in vivo, 139 patients withacute aortic dissection (96 men, 43 women, mean age 60.5 ±15.7 years) were studied by transoesophageal echocardiography(TEE) using 3.5 and 5.0 MHz transducers. Left ventricular hypertrophyby TEE, defined as an end-diastolic wall thickness of the leftventricular septal wall over 1.5 cm, was found in 42 (67.7%)of 62 patients with type I, in 10 (58.8%) of 17 patients withtype II and in 46 (76.7%) of 60 patients with type III dissection.The mean value for the aortic root diameter was 3.2 ±1.3 cm. m^–2 in type I dissection and 2.8 ± 0.9cm. m^–2 (ns) in type II dissection. In the patient groupwith type III dissection this diameter was significantly smaller(1.8 ± 0.9 cm m^–2; P<0.001). Thickening of aorticvalve leaflets was demonstrated in six (9.7%) of 62 patientswith aortic dissection type I (two of them with mild aorticstenosis), in two (11.8%) of 17 patients with aortic dissectiontype II and in 15 (25.0%) of 60 patients with aortic dissectiontype III. A bicuspid aortic valve was diagnosed in five (6.3%)of 79 patients with aortic dissection types I and II and inone (1.7%) of 60 patients with type III dissection. By colourcoded Doppler echocardiography, aortic regurgitation was foundin 46 (74.2%) of 62 patients with type I, 13 (76.5%) of 17 patientswith type II and 23 (38.3%) of 60 patients with type III dissection.A coarctation of the aorta was present in two patients. TEE allows the diagnosis of aortic dissection, as well as ofaccompanying pathologies of the aorta and aortic valve. Factorspredisposing for aortic dissection can be detected in vivo.     

三分支主动脉弓覆膜支架在Stanford A型主动脉夹层手术中的应用

目的总结三分支主动脉弓覆膜支架治疗StanfordA型主动脉夹层的临床经验。方法正中开胸,股动脉、右房插管转流,不游离主动脉弓及头臂血管,鼻温18℃,停循环,于无名动脉近端2cm部分切开升主动脉,直视下置入三分支主动脉弓覆膜支架于主动脉弓和近端降主动脉及三支头臂血管内,行左颈总动脉、右无名动脉气囊导管选择性脑灌注,吻合支架血管近端与升主动脉人工血管,恢复全身灌注。观察并发症及疗效。出院时和3个月复查CT血管造影（CTA）。结果本组无死亡,手术过程顺利,脑及右上肢停循环6-7min,左上肢及降主动脉停循环25-27min,心肌血运阻断时间81-96min,体外循环时间145-190min。术后64排CTA示1例左锁骨下动脉支架外左侧少量血流流向降主动脉,3个月时消失;术后短暂、轻度精神症状1例;二次开胸止血1例,与血管吻合无关。术后1周及3个月CTA示支架血管位置满意,各头臂血管血流通畅。结论三分支主动脉弓覆膜支架术中置人治疗A型主动脉夹层具有操作简单、并发症少、临床效果好等优点,值得临床推广应用。     

3D morphometric analysis of ascending aorta as an adjunctive tool to predict type A acute aortic dissection

BackgroundAcute type A aortic dissection (AAAD) is a pathological process that implicates the ascending aorta and represents a surgical emergency burdened by high mortality if not promptly treated in the first hours of onset. Despite best efforts, the annual incidence rates of aortic dissection has remained stable over the past decades. We measured aortic dimensions (aortic diameters, area, length and volume) using 3D multiplanar reconstruction imaging with the purpose of refining the risk- morphology for AAAD.MethodsComputerized tomography angiography studies of three groups were compared retrospectively: patients affected by AAAD (AAAD group; n=71), patients affected by aortic aneurysm and subsequently subjected to ascending aorta replacement (Aneurysm, n=77) and a healthy aorta’s group (Control, n=75).ResultsMean diameters of AAAD (4.9 cm) and Aneurysm (5.1 cm) aortas were significantly larger than those of the control group (3.4 cm). In AAAD patients, an ascending aorta diameter greater than 5.5 cm was observed in 18% of patients. Multiple comparisons showed statistically significant differences among mean of the ratio of aortic root area to height between the three groups (P<0.001). In frontal and sagittal planes, the length of the ascending aorta was significantly greater in patients affected by aortic pathology (AAAD and aneurysm) than in the control group (P<0.001). Significant differences were confirmed when indexing the aortic length to patient’s height and BSA, and the aortic volume to patient’s BSA.ConclusionsMaximum transverse diameter, considered separately, is not the best predictor of aortic dissection. In our opinion, the introduction into clinical practice of measurements of the area, length, and volume of the aorta, as absolute or indexed values, could improve the selection of patients who would benefit from preventive surgical aortic replacement.     

Three-dimensional echocardiography of the thoracic aorta

OBLECTIVES: The feasibility and diagnostic potential of three-dimensionalechocardiography, using transoesophageal multiplane echocardiographyfor the assessment of thoracic aortic pathology, has not beenevaluated. METHODS: We studied 21 patients (10 women, 11 men), mean age 52·1years (range 20–78). Images for three dimensional reconstructionwere acquired during a diagnostic multiplane transoesophagealechocardiographic examination. In all, 30 acquisitions wereperformed: 19 of the ascending aorta and 11 of the arch anddescending aorta. Three-dimensional reconstruction was performedto visualize normal aortic segments in three patients with anormal thoracic aorta, postoperative anatomy in seven, chronicaortic dissection in two, non-dissecting aneurysm in seven (threepatients had coexisting thrombi) and protruding aortic atheromain two. RESULTS: Three-dimensional image quality was scored excellent in 17 acquisitions(57%), adequate in 10 (33%) and inadequate in three (l0%). Anyplanetwo-dimensional views of regions of interest of the aorta werereconstructed off-line from the data sets, which provided improvedanalysis with potential for quantitation. Advanced computerassisted imaging modalities (electronic vivisection, lumen castdisplay, detail extraction) were feasible. CONCLUSIONS: We conclude that three-dimensional echocardiography of the thoracicaorta is feasible. Adequate image quality is obtained in thevast majority of patients, which adds additional qualitativeand quantitative information to routine multiplane transoesophagealechocardiographic studies. (Eur Heart J 1996; 17: 1584–1592)     

Ascending aortic aneurysm and dissection in young adults with bicuspid aortic valve: Implications for echocardiographic surveillance

Bicuspid aortic valve (BAV) is an independent risk factor for aneurysm and dissection of the ascending aorta. Despite this association, routine imaging of the aorta has not been recommended for patients with BAV. We describe two young men who developed life-threatening aneurysm or dissection of the ascending aorta; one had a normally functioning BAV and the other was 10 years after valve replacement. The pathology of this condition is very similar to that found in the Marfan syndrome. We recommend echocardiographic surveillance of the ascending aorta at regular intervals, and consideration of beta-adrenergic blockade among patients with significant dilation.     

“象鼻”支架术治疗Stanford B型主动脉夹层胸主动脉腔内修复术后Ⅰ型内漏

目的:回顾应用支架"象鼻"术治疗Stanford B型主动脉夹层胸主动脉腔内修复术(TEVAR)术后Ⅰ型内漏的临床效果。方法:2009年3月至2013年1月,首都医科大学附属北京安贞医院,收治的Stanford B型主动脉夹层TEVAR术后Ⅰ型内漏12例患者进行回顾性分析。12例患者均为男性,平均年龄(50.2±6.2)岁,平均身高(171.92±4.98)cm,平均体质量(77.50±8.43)kg,所有患者均无相关家族遗传病史,均有高血压病史,与第一次TEVAR术间隔时间平均34.4个月。支架"象鼻"术均在全麻体外循环下进行。如漏口暴露清楚,可缝闭漏口;如置入支架裸区妨碍象鼻支架缝合,可剪除部分裸露部分金属支架或将置入支架取出;如漏口累及左锁骨下动脉开口,可将左锁骨下动脉近端缝闭,截断左锁骨下动脉,其远端与左颈总动脉行端侧吻合,建立左颈总动脉至左锁骨下动脉转流或8mm人工血管行升主动脉至左腋动脉或左锁骨下动脉转流。于之前置入的支架内置入26~30mm Microport术中支架血管,覆盖内漏破口。术后随访6~48个月,平均6.53个月。结果:12例支架"象鼻"术均为择期手术,其中7例患者漏口位置累及左锁骨下动脉,4例剪除置入支架金属裸区;1例将置入支架取出;3例术中支架血管近端吻合于左锁骨下动脉以远,8例吻合于左颈总动脉与左锁骨下动脉之间;4例同期行左颈总动脉至左锁骨下动脉转流术;2例行升主动脉-左锁骨下动脉转流术;2例行升主动脉-左腋动脉转流术;1例患者因合并二尖瓣关闭不全同期行二尖瓣置换术;1例合并迷走右锁骨下动脉的患者同期行升主动脉-右腋动脉转流术。12例患者手术时间为平均(5.92±1.14)小时,平均住院时间为(21.92±9.14)天,2例患者术后出现围术期并发症,其中1例胸骨哆开,行再次胸骨固定痊愈;1例术前肾功能不全,术后出现急性肾衰竭,经透析治疗后肾功能恢复。本组患者均顺利出院。所有患者术后内漏均消失,术后随访6~48个月,平均6.53个月,均无复发。在术后随访期间,3例患者支架远端病变需再次处理,1例患者术后7个月出现支架感染、咯血、死亡。结论:应用支架"象鼻"术治疗Stanford B型主动脉夹层TEVAR术后Ⅰ型内漏,有较好的临床疗效,但远期效果仍需进一步观察。     

Application of thoracic endovascular dissecting aneurysm repair for secondary type B aortic dissection

Type A aortic dissection is an emergency condition that requires immediate surgery. Graft replacement of the ascending aorta is the main treatment for this disorder. However, after ascending aortic replacement, the dissection flap may progress to the distal side (to the descending aorta) and a new intimal tear may develop. In this study, we report on a 66-year-old woman who had a history of ascending aortic replacement six months earlier. She was admitted to hospital with a new onset of back pain. Computed tomography revealed a new dissection tear originating from the distal side of the subclavian artery orifice. Thoracic endovascular dissecting aneurysm repair (TEVDAR) was carried out on the patient. Additional complications were not observed in the postoperative period. Complete cure was provided and the patient was discharged on the fourth day after the operation. TEVDAR may be safe and effective in preventing progression of the aortic flap and the formation of a new intimal tear in type A aortic dissections. Optional hybrid interventions could ameliorate the outcomes in aortic dissection cases.     

支架型人工血管介入治疗主动脉夹层动脉瘤及主动脉穿透溃疡30例报告

目的探讨支架型人工血管介入治疗主动脉夹层动脉瘤和主动脉穿透溃疡的可行性及疗效。方法2001年6月至2004年3月,行支架型人工血管治疗主动脉夹层动脉瘤及主动脉穿透溃疡30例。男性24例,女性6例。平均年龄(523±119)岁。25例主动脉夹层动脉瘤中,慢性TypeB23例,急性TypeB1例,TypeA1例。主动脉穿透溃疡5例。术后随诊1～32个月。结果30例支架型人工血管均成功植入。5例有近端内漏,1例术中发生升主动脉夹层,2例分别在术后1d、7d发生升主动脉夹层。术后30d内死亡2例。术后30d内死亡率为67%。1例术后20个月因近端内漏接受第2次支架型人工血管植入术。术后随诊1～32个月,无死亡,亦无支架移位、狭窄等并发症。结论支架型人工血管是治疗主动脉夹层动脉瘤和主动脉穿透溃疡的有效方法,中远期效果还有待进一步观察。     

Functional characteristics of myocardial bridging: A combined angiographic and intracoronary Doppler flow study

AIMS: Combined quantitative coronary angiography and intracoronaryDoppler flow velocity measurements were performed to study theunderlying haemodynamic mechanisms leading to myocardial ischaemiain patients with myocardial bridging in the absence of coronaryartery disease. METHODS AND RESULTS: In 42 symptomatic patients with myocardial bridging of the leftanterior descending coronary artery, quantitative coronary angiographywas used to measure absolute and relative vessel diameters duringsystole and diastole. In 14 patients, serial frame-by-framediameter quantification during a complete cardiac cycle wasperformed. Intracoronary blood flow velocities were determinedusing a 0·014 inch Doppler flow guide wire proximal,within, and distal to myocardial bridges, and coronary flowreserve was calculated. Quantitative coronary angiography revealeda maximal systolic lumen diameter reduction of 71 ± 16%with a persistent diameter reduction of 35 ± 13% duringmid-diastole. Flow velocities revealed increased average diastolicpeak flow velocities within myocardial bridges of 38·6± 19 cm. s^–1 vs 22·4 ± 7·7cm. s^–1 proximal and 18·6±4·6cm.s^–1 distal (P<0·001), which increased duringrapid pacing (64·7 ± 25 cm. s^–1, P<0·001vs baseline). Coronary flow reserve distal to myocardial bridgeswas 2·3 ± 0·9 (vs 2·9 ± 0·9proximal, P<0·05). There was a characteristic Dopplerflow profile within myocardial bridges with an early diastolicovershoot, which was further augmented during rapid pacing. CONCLUSION: Myocardial bridging is characterized by a delay in diastoliclumen gain and a concomitant increase in diastolic intracoronaryDoppler flow velocities, which are enhanced by rapid pacing.In combination with a reduced coronary flow reserve and anginalsymptoms these findings support the concept of a haemodynamicallysignificant obstruction to coronary flow due to myocardial bridgingin a selected subset of patients.     

Outcome of reoperative aortic root or ascending aorta replacement after prior aortic valve replacement

BackgroundThere are limited data regarding the clinical outcomes of reoperative aortic root or ascending aorta replacement after prior aortic valve replacement (AVR). We aimed to analyze outcomes of reoperative aortic root or ascending aorta replacement after prior AVR.MethodsEighty patients with prior AVR underwent reoperative aortic root or ascending aorta replacement in our hospital. The indications were root or ascending aortic aneurysm in 36 patients, root or ascending aortic dissection in 37, root false aneurysm in 2, prosthesis valve endocarditis (PVE) with root abscess in 2, Behçet’s disease (BD) with root destruction in 3 patients. An elective surgery was performed in 63 patients and an emergent surgery in 17. The survival and freedom from aortic events during the follow-up were evaluated with the Kaplan-Meier survival curve and the log-rank test.ResultsThe operative techniques included ascending aorta replacement in 14 patients, ascending aorta replacement with AVR in 3, prosthesis-sparing root replacement (PSRR) in 35, Bentall procedure in 24, and Cabrol procedure in 4 patients. Operative mortality was 1.3% (1/80). A composite of adverse events occurred in 5 patients, including 1 operative death, 2 stroke and 3 renal failure necessitating hemodialysis. The mean follow-up was 35.5±22.1 months. Five late deaths occurred. The Kaplan-Meier survival at 1 year, 3 years and 6 years were 97.5%, 91.1% and 84.1%, respectively. Aortic events developed in 3 patients. The freedom from aortic events at 1-year, 3-year, and 6-year were 100%, 96.3% and 88.9%, respectively. There were no differences in survival and freedom from aortic events between the elective group and the emergent group.ConclusionsReoperative aortic root or ascending aorta replacement after prior AVR could be performed to treat the root or ascending pathologies after AVR, with satisfactory early and midterm outcomes.     

Influence of the force--frequency relationship on haemodynamics and left ventricular function in patients with non-failing hearts and in patients with dilated cardiomyopathy

In isolated human myocardium it was shown that a positive force-frequencyrelationship occurs in non-failing myocardium; however, theforce-frequency relationship was found to be inverse in myocardiumfrom failing human hearts. In order to investigate the clinicalrelevance of these experimental findings, the influence of heartrate changes on haemodynamics and left ventricular functionwas studied in eight patients without heart failure and in ninewith failing dilated cardiomyopathy (NYHA II–III). Rightventricular pacing was performed at a rate slightly above sinusrate and at 100, 120 and 140 beats. min^–1 Haemodynamicparameters were obtained by right heart catheterization andby high-fidelity left ventricular pressure measurements. Leftventricular angiography was performed at basal pacing rate andat 100 and 140 beats. min^–1 With increasing heart rate,cardiac index increased in patients with normal left ventricularfunction from 2·9 ± 0·2 to 3·5 ±0·21. min^–1. m^–2 (P<0·01) and decreasedcontinuously in patients with dilated cardiornyopathy from 2·6± 0·1 to 2·2 ± 0·11. min^–1. m^–2 (P<0·05). With increasing heart rate,the maximum rate of left ventricular pressure rise increasedin non-failing hearts from 1388 ± 86 to 1671 ±88 mmHg. s^–1 (P<0·01) and did not change infailing hearts. Ejection fraction decreased from 27 ± 3% to 19 ±2% in patients with dilated cardiomyopathy (P<0·05)when the pacing rate was changed from 84 ± 2 beats. min^–1to 140 beats. min^–1, which was associated with a significantlyincrease in end-systolic volume without significantly changesin end-diastolic volume. In patients with normal left ventricularfunction, when the pacing rate was changed from 85 ±3 beats. min^–1 to 140 beats. min^–1, end-diastolicvolume decreased significantly by 13%, whereas left ventricularend-systolic volume and ejection fraction did not significantlychange. Left ventricular systolic and end-diastolic pressuresdid not significantly change with pacing tachycardia in eithergroup. The frequency-related changes in left ventricular volumesand pressures indicate that the differrent haemodynamic effectsof pacing tachycardia in both groups of patients result predominantlyfrom frequency effects on myocardial function and not from frequencyeffects on preload or afterload. These data indicate that recentexperimental findings of positive force-frequency effects innon-failing and negative force-frequency effects in failinghuman myocardium are relevant for the intact heart.     

Endovascular stent-grafts for acute and chronic type B aortic dissection: comparison of clinical outcomes

Within the recent months, endovascular repair of aor- tic aneurysms has become a rather interesting alternative to patients considering open surgery. In the past, the proce- dure was typically and more solely reserved to a selected group of elderly patients with several co-morbidities. Currently, there are a number of ongoing trials that are com-     

Physical training improves exercise capacity in patients with mitral stenosis after balloon valvuloplasty

BACKGROUND: Haemodynamic measurements taken at rest and during exerciseshowed that percutaneous transvenous mitral commissurotomy resultsin both acute and long-term improvement. However, the time lagbefore there is an increase in exercise and in peak oxygen uptakeappears to be delayed and irregular. PATIENTS AND METHODS: To assess the potential of physical training to restore betterphysical capacity after percutaneous transvenous mitral commissurotomy,26 patients with mitral stenosis were studied after the procedure.The group was split into two. Thirteen underwent a 3-month rehabilitationprogramme, and the other 13, who did not, acted as controls. RESULTS: The mitral valve orifice area increased similarly, from 1·;12±017to 1·88 ±0·28 cm² in the training groupand from 1·04±0·16 to 1·88±0·19cm² in the control group. Cardiopulmonary parameters were similarbefore percutaneous transvenous mitral commissurotomy (peako₂: 19·9±2·4 vs 18·9±4·5ml. min^–1. kg^–1; peak workload: 94·6±29·3vs 96·1±25 watts; o₂ at anaerobic threshold: 17±3·4vs 16·1±5·2 ml. .min^–1. kg^–1;all P=ns). Three months later the results were higher in thetraining group (peak o₂: 26·6±4·7 vs 21·6±3·8ml. min^–1. kg^–1, P=0·001; peak workload:125·4±26·6 vs 108·5±23 watts,p=0·03; o₂ at anaerobic threshold: 19·6±5·8vs 15·8±2·9 ml. min^–1. kg^–1;P=0·02). CONCLUSION: These results indicate that patients should take up exerciseafter successful percutaneous transvenous mitral commissurotomyfor better functional improvement.     

Clinical, adrenergic and heart endocrine measures in chronic atrial fibrillation as predictors of conversion and maintenance of sinus rhythm after direct current cardioversion

The aim of this study was to evaluate clinical, adrenergic andendocrine factors that could predict sinus rhythm maintenanceafter direct current cardioversion in chronic atrial fibrillation. Nineteen patients with chronic non-rheumatic atrial fibrillation(mean duration 6±5 months) were studied. They were exercised24 h before cardioversion at maximum effort with the Naughtonprotocol. Heart rate and blood pressure at rest and exercisewere recorded and blood samples were taken for the assessmentof adrenergic activity, by measuring cyclic adenosine monophosphate,heart endocrine function, atrial natriuretic peptide and itssecond messenger, cyclic guanosine monophosphate. Fifteen ofthe 19 patients were initially converted to sinus rhythm (eightpatients with external and seven patients with internal DC shocks).After 3 months eight patients remained in sinus rhythm and 11had relapsed, most of them within the first month. On exercisethe chronotropic response was lower in the group who remainedin sinus rhythm than in the group in atrial fibrillation (peakheart rate 147±11 beats.min^–1 vs 165±24beats.min^–1 p=0·02). During exercise, the systolicblood pressure in the sinus group reached higher values thanin the group who relapsed (192±17 mmHg vs 176±18mmHg, p=0·03). Cyclic adenosine monophosphate increasedsignificantly from rest to peak exercise in the sinus rhythmgroup (from 23±9 pmol.ml^–1 to 31±15 mol.ml^–1,p=0·02) while it remained unchanged in the atrial fibrillationgroup (25±10 pmol.ml^–1 to 24±8 pmol.ml^–1,p=0·02). For all 19 patients the differ ence in cyclicadenosine monophosphate between rest and exercise was negativelycorrelated with maximum heart rate (r=0·58, p=0·009).Atrial natriuretic peptide increased from rest to peak exercisein the sinus rhythm group (from l29±58 fmol.ml^–1to 140±66fmol.ml^–1 while it remained unchangedin the group in which atrial fibrillation persisted or recurred(from 112±58 fmol.ml^–1 to 111±53 fmol.ml^–1p=0· A significant correlation between atrial natriureticpeptide and cyclic guanosine monophosphate levels at exercisebefore cardioversion was found for the sinus rhythm group only(r=0·76, p=0·02). In patients with non-rheumatic chronic atrial fibrillation evaluationof clinical parameters such as heart rate and blood pressurechanges during maximal exercise can be useful in the choiceof suitable therapy. An inadequate increase in plasma cyclic-adenosinemonophosphate and atrial natriuretic peptide on exercise couldpredict patients with more severe underlying disease, wherecardioversion should not be recommended.     

Stanford A型主动脉夹层的外科治疗

目的 总结A型主动脉夹层外科治疗经验,探讨治疗A型主动脉夹层安全有效的术式和方法.方法 我院2008年1月至2013年11月对40例A型主动脉夹层患者予以外科治疗.Bentall（带瓣人造血管替代升主动脉根部和主动脉瓣膜,并移植左右冠状动脉）手术17例,其中10例同期行主动脉弓部替换＋降主动脉象鼻支架置入术;单纯升主动脉人工血管置换术8例;窦部成形＋主动脉瓣交界悬吊术6例,窦部替换＋主动脉瓣成形＋升主动脉半弓替换5例;升主动脉人工血管置换术＋主动脉全弓替换4例.采用深低温停循环技术（DHCA）12例,其余为浅中低温体外循环.采用冷血心脏停搏液灌注12例,组氨酸-色氨酸-酮戊二酸（HTK）停搏液灌注7例,冷晶体心脏停搏液21例.采用改良超滤技术19例.结果 手术死亡1例,围术期死亡4例,死亡率12.5％（5/40）,余均痊愈出院.结论 细化A型主动脉夹层的分型有利于制订个体化手术方案.术中止血彻底及心肌、脑保护确切可提高手术成功率.     

Natural history of a dilated ascending aorta after aortic valve replacement.

BACKGROUND: Little information is available regarding the incidence of aortic dissection or rupture in patients with a dilated ascending aorta after aortic valve replacement (AVR). The present clinical study aimed to demonstrate the incidence of aortic complications after AVR in patients with a dilated ascending aorta and to clarify those risk factors associated with the progression of a dilated ascending aorta or late aortic events. METHODS AND RESULTS: A total of 35 patients with a dilated ascending aorta at the time of AVR were enrolled. A dilated ascending aorta was defined as 40 mm or greater in diameter by preoperative computed tomography or operative findings. The baseline ascending aorta diameter ranged from 40 to 55 mm with a mean of 44.8+/-4.4 mm. There was a high frequency of bicuspid valve disease in patients with a dilated ascending aorta (57%). The mean follow-up interval was 8.1+/-3.5 years (range: 2.3-13). Aortic events occurred in 5 patients (aortic dissection in 1, rupture in 2, reoperation in 2) during the follow-up. One aortic dissection developed at a baseline aortic size of 42 mm, whereas 2 aortic ruptures occurred at baseline aortic sizes of 47 mm and 50 mm. There was no statistically significant univariate association between any of the patient clinical characteristics and late aortic events or ascending aortic progression. CONCLUSION: Although the clinical course of patients with a dilated ascending aorta is unpredictable, aortic events may occur even in patients with a baseline aortic diameter of <50 mm. Therefore, preventive aortic surgery at the time of AVR should be considered to prevent aortic dissection or rupture in patients with an even slightly dilated ascending aorta with a diameter of 40 to 50 mm, unless the patient has a high operative risk or older age.     

Effects of percutaneous balloon mitral valvuloplasty and exercise training on the kinetics of recovery oxygen consumption after exercise in patients with mitral stenosis

Aims Kinetics of recovery oxygen consumption after exercise playsan important role in determining exer-cise capacity. This studywas performed to assess the kinetics of recovery oxygen consumptionin mitral stenosis and evaluate the effects of percutaneousballoon mitral valvuloplasty and exercise training on the kinetics. Methods and Results Thirty patients with mitral stenosis (valve area 1·0cm²)and same sized age- and size-matched healthy volunteers wereincluded for this study. All subjects performed maximal uprightgraded bicycle exercise. Thirty consecutive patients who underwentsuccessful percutaneous balloon mitral valvuloplasty (valvearea 1·5cm²and mitral regurgitation grade 2), were randomizedto an exercise training group or non-training group. The exercisegroup performed daily exercise training for 3 months. Half-recoverytime of peak oxygen consumption was significantly delayed inmitral stenosis as compared to normal subjects (120±42svs 59±5,P<0·01). Peak oxygen consumption (ml.min^–1.kg^–1)was significantly increased in both the training (16·8±4·9to 25·3±6·9) and non-training groups (16·3±5·1to 19·6±6·0) 3 months after percutaneousballoon mitral valvuloplasty. Half-recovery time of peak oxygenconsumption was significantly shortened in the training group(124±39 to 76±13,P<0·01), but not inthe non-training group (114±46 to 109±44s,P=0·12)at 3 months follow-up. The degrees of symptomatic improvementafter percutaneous balloon mitral valvuloplasty were more closelycorrelated with the changes of the half-recovery time of peakoxygen consumption than those of peak oxygen consumption. Conclusion Kinetics of recovery oxygen consumption was markedly delayedin mitral stenosis, which was improved after exercise trainingbut not after percutaneous balloon mitral valvuloplasty alone.These results suggest that adjunctive exercise training maybe useful for improvement of recovery kinetics and subjectivesymptoms after percutaneous balloon mitral valvuloplasty.     

Age-related transmural peak mean velocities and peak velocity gradients by Doppler myocardial imaging in normal subjects

Doppler myocardial imaging is a new cardiac ultrasound techniquebased on the principles of colour Doppler imaging which candetermine myocardial velocities by detecting the changes ofphase-shift of the ultrasound signal returning directly fromthe myocardium. To determine the normal range of transmuralvelocities in healthy hearts a prospective study was carriedout involving 42 normal subjects (age from 21 to 78, mean 47±16years). Using M-mode Doppler myocardial imaging the peak valuesof the mean velocity and velocity gradient across the left ventricularposterior wall were measured during standardized phases of thecardiac cycle. Peak mean velocities had the following valuesduring the cardiac cycle: isovolumic contraction –1·3±1·2cm.s^–1, early ventricular ejection 4·2±1·2cm.s^–1, late ventricular ejection 1·8±1·1cm.s^–1, isovolumic relaxation –2·0±0·8cm.s^–1, rapid ventricular filling –6·6±2·2cm.s^–1, atrial contraction –2·8±1·8cm.s^–1, atrial relaxation 1·2±1·1cm.s^–1. Peak velocity gradients were: isovolumic contraction1·3±1·9 s^–1, early ventricular contraction4·7±1·9s^–1, late ventricular contraction1·1 ±1·0 s^–1, isovolumic relaxation–0·6±0·5 s^–1, rapid ventricularfilling 6·1±3·4 s^–1, atrial contraction2·6±1·7 s^–1, atrial relaxation 0·0±0·3s^–1. Linear regression analysis showed that with the increaseof age, peak velocity gradient decreases during rapid ventricularfilling (r=0·83; P<0·0001) and increases duringatrial contraction (r=0·86; P<0·0001) whilepeak mean velocity increases only during atrial contraction(r=0·80, P<0·0001). Thus, there was no correlationbetween increasing age and systolic peak mean velocity and peakvelocity gradient but both diastolic filling phases rapid ventricularfilling and atrial contraction demonstrated age-related changes. In summary, this study has determined the age-related rangeof normal transmural myocardial velocities within the left ventricularposterior wall in healthy hearts during the cardiac cycle. Weconclude that these measurements of peak mean velocities andpeak velocity gradients, should form the baseline for subsequentDoppler myocardial imaging clinical studies on myocardial diseasesprocesses.