Assessment of left internal mammary artery graft patency and flow reserve after minimally invasive direct coronary artery bypass.

Despite its merits, minimally invasive direct coronary artery bypass surgery (MIDCAB) has been criticized for variable left internal mammary artery (LIMA) graft patency rates, prompting the frequent use of postoperative LIMA angiography. Noninvasive transthoracic Doppler interrogation of LIMA grafts has recently been shown to have utility for assessing patency and flow reserve after conventional bypass surgery, but data after MIDCAB has been limited. The objective of this study was to assess LIMA graft anatomy and physiology in 54 patients after MIDCAB using angiography and noninvasive LIMA Doppler imaging. The right internal mammary artery (RIMA) was studied as a control. LIMA flow reserve in response to adenosine was evaluated in a subgroup of 18 randomly chosen patients with patent grafts. LIMA angiographic patency was 93%. Forty-four patients (81%) had obtainable LIMA Doppler data. Patent grafts had a diastolic dominant flow pattern with a peak diastolic/systolic velocity ratio of 1.3 +/- 0.6 and a percent diastolic time-velocity integral (TVI) of 70 +/- 11%. These data were significantly different than the RIMA control values of 0.2 +/- 0.1 and 30 +/- 10%, respectively (p <0.05). Occluded grafts had absent flow or a systolic dominant pattern. Adenosine-induced increases in LIMA peak diastolic velocity from 48 +/- 20 to 105 +/-28 cm/s (p <0.05 vs baseline) and diastolic TVI from 21 +/- 10 to 37 +/- 19 cm (p <0.05 vs baseline), yielding adenosine/baseline ratios of 2.4 +/- 0.9 and 2.0 +/- 0.7, respectively, which was consistent with normal flow reserve. The diastolic flow velocity reserve response was inversely related to baseline diastolic flow (r = -0.69). In conclusion, MIDCAB can be associated with a high rate of LIMA potency and favorable physiologic Doppler flow patterns. Correlation of these findings to long-term patient outcome after MIDCAB is warranted.     

Left internal mammary artery grafting to left anterior descending coronary artery by minimally invasive direct coronary artery bypass approach

New surgical techniques for the treatment of the isolated lesion of the left anterior descending coronary artery (LAD) include off-pump surgery, minimal access to the heart, and endoscopic or computer enhanced coronary artery bypass surgery. The term minimally invasive direct coronary artery bypass surgery (MIDCAB) is related to a leftside minithoracotomy, the harvest of the left internal mammary artery (IMA) under direct vision, and an anastomosis performed between IMA and LAD under direct vision, using the technique of mechanical local immobilization by a special device. Alternative techniques include endoscopic harvesting of the IMA, or as a new and still experimental approach, the closed-chest total endoscopic coronary artery bypass grafting (TECAB) with the use of a high tech telemanipulator system. The currently reported results demonstrate the safety of MIDCAB surgery (30-day mortality < 0.5%, perioperative myocardial infarction < 2%, early patency rate between 95% and 98%). Mid-term results after 6 months have shown a patency rate between 94% and 97%, and more than 90% of the patients are without any angina symptoms. Due to this promising results MIDCAB is an alternative treatment for high-grade LAD lesions.     

Coronary bypass grafting without cardiopulmonary bypass--technical considerations, clinical results, and follow-up

BACKGROUND: Coronary bypass surgery can be performed less invasively by avoiding cardiopulmonary bypass (CPB). We present our early 'off pump' coronary bypass surgery experience in combination with a minithoracotomy or sternotomy. METHODS: Between 11/1996 and 12/1997 312 patients were included in a prospective study, 223 (Group A) underwent an antero-lateral minithoracotomy (MIDCAB) and 89 (Group B) had a full sternotomy (OPCAB). ITA harvesting and anastomosis was performed under direct vision in all cases. Different devices for local mechanical immobilization were used to perform the anastomosis. RESULTS: In 212 patients of group A revascularization was by a single ITA graft and in 11 patients by a double graft using the radial artery as a T graft. Conversion to sternotomy and cardiopulmonary bypass was necessary in 12 (5.3%) patients. Intraoperative myocardial infarction was observed in 5 patients (2.2%). Early-postoperative reoperation due to graft failure was necessary in 5 patients (2.2%). Mortality was 0.4% (one patient). The early postoperative graft patency rate was 97.1% as confirmed by angiography. In group B, 25 patients had single graft and 64 patients multiple graft revascularization. Intraoperative conversion to CPB was necessary in 10 patients (11.2%). Intraoperative myocardial infarction occurred in 1 patient (1.1%), postoperative low output syndrome in 2 patients (2.2%). Early postoperative reoperation due to graft failure was necessary in 1 patient (1.1%). Mortality was 1.1%. Angiographic control of 48 patients after 6 months confirmed a patency rate of 92.6%. CONCLUSION: Coronary bypass surgery without using cardiopulmonary bypass is safe to achieve good early and mid-term results. MIDCAB is a minimally invasive technique. Experienced surgeons should be ready to compete with PTCA techniques.     

Awake off- pump coronary artery bypass surgery in 25 patients

Objectives To test the feasibility of the use of high thoracic epidural anesthesia as a sole anesthetic in patients undergoing off pump coronary artery bypass surgery, avoiding general anesthesia. Methods Between October 2002 to April 2003, twenty five cases underwent beating heart coronary artery revascularization without endotracheal general anesthesia, using high thoracic epidural anesthesia and analgesia. All the patients underwent epidural catheterization on the evening before the surgery. Resuits The patients in all received 71 grafts (single n= 11, double n = 5, triple n = 6, quadruple n =3). Six patients underwent repeat coronary artery bypass. Except one was converted to general anesthesia and cardiopulmonary bypass, the other patients underwent off- pump coronary artery bypass graft surgery, 2 patients underwent grafting via left thoracotomy (MIDCAB) and the rest through mid sternotomy. There was no mortality. Mean length of stay in the intensive care unit was 16 . 2 ( 4.2 hours and hospital was 3.0(1.2 days. Conclusions Our experience confirms the feasibility of performing muhiple coronary artery bypasses in conscious patients without endotracheal general anesthesia.     

Diabetes in patients undergoing coronary artery bypass grafting. Impact on perioperative outcome

Summary Diabetes mellitus is an established risk factor related to significant morbidity and mortality after coronary artery bypass grafting. Data on 9682 patients undergoing coronary artery bypass grafting either with (n=8917) or without cardiopulmonary bypass (off-pump coronary artery bypass grafting; n=765) were subjected to an univariate analysis to identify potential associations between diabetes mellitus and 26 a priori selected perioperative outcome variables. Those having a significant association with diabetes were then subjected to a stepwise logistic regression model to identify the impact of diabetes as compared to additional 22 different a priori chosen patient related risk factors and treatment variables. Prevalence of outcome variables independently associated with diabetes has been determined in the subgroup of diabetics undergoing coronary artery bypass grafting with cardiopulmonary bypass or off-pump coronary artery bypass grafting surgery to evaluate the effect of avoiding cardiopulmonary bypass on perioperative patient outcome. Diabetes mellitus was defined as glucose intolerance either treated dietary, with oral hypoglycemics or with insulin. According to this definition of diabetes mellitus we found an overall prevalence of 37.1% (coronary artery bypass grafting with cardiopulmonary bypass: 37.5%; off-pump coronary artery bypass grafting: 32.5%). Eleven outcome variables having a significant association with diabetes were identified. Diabetes could be identified as an independent predictor of postoperative delirium, renal dysfunction and respiratory insufficiency. Prevalence of these three variables was lower in diabetics undergoing offpump coronary artery bypass grafting as in those undergoing coronary artery bypass grafting with cardiopulmonary bypass surgery reaching statistical significance with regard to postoperative delirium and respiratory insufficiency. In conclusion, diabetes mellitus is a significant independent predictor for three postoperative outcome variables in coronary artery bypass surgery. Avoiding cardiopulmonary bypass in diabetics seems to have a beneficial effect.     

Detection of patency of internal mammary artery grafts to the left anterior descending artery by transthoracic Doppler echocardiography

BACKGROUND: To determine whether a coronary artery bypass graft (CABG) is patent, we examined the flow of the left internal mammary artery (LIMA) to the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE). PATIENTS AND METHODS: Eighty-seven patients with CABG (LIMA to distal LAD) were enrolled in the study. The flows from each subject were analyzed by three criteria: mosaic flow at the anastomosis site, distal anterograde flow (ante flow), and proximal retrograde flow (retro flow). RESULTS: On angiography, 79 grafts were patent and eight were not. TTDE study of 79 patent grafts demonstrated mosaic, ante, and retro flow in 63 (79.7%), 74 (93.7%), and 35 grafts (49.4%), respectively. The averaged diastolic peak velocity of ante flow was 26.3 +/- 11.0 cm/sec, significantly higher than that (4.8 +/- 7.1 cm/sec, P < or = 0.0001) in eight patients without patent grafts. These eight patients had no mosaic or retro flow and only three had ante flow. The accuracies to predict patency were 81.6%, 90.8%, and 49.4% for mosaic, ante, and retro flows, respectively. CONCLUSIONS: The existence of mosaic, retro, or sufficient ante flows strongly indicated the patency of LIMA to the LAD. When symptoms are possible to be derived from the occlusion of CABG to LAD, TTDE is a promising method to examine whether a LIMA to LAD bypass is patent.     

Robot-assisted coronary artery bypass grafting improves short-term outcomes compared with minimally invasive direct coronary artery bypass grafting

Background

Robot-assisted coronary artery bypass grafts (RACAB) utilizing the da Vinci surgical system are increasingly used and allow the surgeon to conveniently harvest internal mammary arteries (IMAs). The aim of this study was to compare the outcomes of off-pump RACAB and minimally invasive direct coronary artery bypass grafting (MIDCAB) in the short and medium term.

Methods

We performed a retrospective review of 132 patients with single- or multiple-vessel coronary artery disease who underwent minimally invasive off-pump CABG (OPCAB) between May 2009 and May 2014. The patients were divided into two groups based on the surgical approach, MIDCAB and RACAB group. The anastomosis of the left internal mammary artery (LIMA) to the left anterior descending artery (LAD) was performed as regular OPCAB through the incision on the beating heart using regular stabilization devices (Genzyme Corporation). The preoperative, intraoperative, postoperative, and follow-up data, including major adverse cardiac and cerebrovascular events (MACCE), were compared.

Results

The preoperative data were similar. RACAB significantly shorten the intensive care unit (ICU) stay and postoperative compared with the MIDCAB group (P<0.05). There were 12 (19.7%) patients treated with a two-stage hybrid procedure in the MIDCAB group and 34 (47.9%) patients in the RACAB group (P=0.001). Thirty-day mortality was 1.6% in the MIDCAB group. There were 9 (14.7%) MIDCAB patients and 2 (2.8%) RACAB patients (P=0.013) that developed new arrhythmia. The two groups showed comparable mid-term survival (P=0.246), but the MACCEs were significantly different (P=0.038).

Conclusions

RACAB may be a valuable alternative for patients requiring single or simple multi-vessel coronary artery bypass grafting (CABG). Although the mid-term mortality outcomes are similar, RACAB improves short-term outcomes and mid-term MACCE-free survival compared with MIDCAB.     

Echocardiographic detection of free-floating thrombus in left ventricle during coronary artery bypass grafting

We report an incident of detection of a free-floating thrombus in the left ventricle (LV) using intraoperative two-dimensional (2D) and three-dimensional (3D) transesophageal echocardiography (TEE) during proximal coronary artery bypass graft anastomosis. A 58-year-old man presented to us with a 6-month history of chest pain without any history suggestive of myocardial infarction or transient ischemic attacks. His preoperative echocardiography revealed the systolic dysfunction of LV, mild hypokinesia of basal and mid-anterior wall, and the absence of an aneurysm. He was scheduled for on-pump coronary artery bypass surgery. On intraoperative TEE before establishing cardiopulmonary bypass (CPB), a small immobile mass was found attached to LV apical area. After completion of distal coronary artery grafting, when the aortic cross-clamp was removed, the heart was filled partially and beating spontaneously. TEE examination using 2D mode revealed a free-floating mass in the LV, which was suspected to be a thrombus. Additional navigation using biplane and 3D modes confirmed the presence of the thrombus and distinguished it from papillary muscles and artifact. The surgeon opened the left atrium after re-establishing electromechanical quiescence and removed a thrombus measuring 1.5 cm × 1 cm from the LV. The LV mass in the apical region was no longer seen after discontinuation of CPB. Accurate TEE-detection and timely removal of the thrombus averted disastrous embolic complications. Intraoperative 2D and recent biplane and 3D echocardiography modes are useful monitoring tools during the conduct of CPB.     

Percutaneous coronary intervention with drug-eluting stent implantation vs. minimally invasive direct coronary artery bypass (MIDCAB) in patients with left anterior descending coronary artery stenosis.

The aim of this study was to assess the effects of percutaneous coronary intervention with drug-eluting stents (DESs) versus minimally invasive direct coronary artery bypass (MIDCAB) surgery in the management of patients with proximal left anterior descending (LAD) coronary artery stenosis. Until recent years, despite the advantages of percutaneous transluminal coronary angioplasty (PTCA) with bare metal stent implantation, such as shorter hospital stays and recovery time, MIDCAB showed better results with regard to the need for repeated intervention in the target vessel than PTCA with proximal LAD lesions. Symptomatic patients (n = 189) were randomly assigned to DES group (n = 119) and MIDCAB group (n = 70). Patients with an isolated high-grade lesion (stenosis of > or = 70% of the luminal diameter) in the proximal LAD coronary artery (from the ostium to the first diagonal branch) were included in this study. During the 6-month follow-up period, 1.7% (n = 2) in the DES group needed repeated revascularization procedures for target lesion revascularization compared with 5.9% (n = 4) in the MIDCAB group (P = 0.196). The rates of death and myocardial infarction were similar in both groups [DES 0.0% (n = 0) vs. MIDCAB 2.9% (n = 2), P = 0.135; DES 1.7% (n = 2) vs. MIDCAB 2.9% (n = 2), P = 0.627; respectively] during 6 months of follow-up. In-hospital length of stay was significantly shorter in the DES group compared with the MIDCAB group (5.8 +/- 2.1 days vs. 8.9 +/- 2.6 days; P = 0.001). DES implantation and MIDCAB surgery showed similar rates of myocardial infarction, the need for repeated revascularization, and death during 6 months of follow-up. However, DES implantation resulted in lower average number of hospital stays and similar postoperative complications.     

Systemic venous flow during cardiac surgery examined by intraoperative transesophageal echocardiography.

Patterns of systemic venous return change after cardiac surgery. However, the exact timing and underlying mechanisms are not well understood. To analyze these changes transesophageal echocardiography was used to evaluate 21 patients (mean age 56 +/- 17 years) during cardiac surgery. Eleven patients underwent coronary bypass grafting, 2 had ablation of accessory bundles, 4 had mitral and 4 had aortic valve replacements. All were in sinus rhythm and were undergoing their first cardiac operation. Hepatic and pulmonary venous flow, tricuspid annular motion, and signs of tricuspid regurgitation were recorded sequentially 5 times: (A) with chest closed, (B) with chest open and pericardium closed, (C) with both chest and pericardium open, (D) after cardiopulmonary bypass with chest open, and (E) after cardiopulmonary bypass with chest closed. The hepatic venous Doppler flow velocity integrals (cm) changed, from stage A to stage E: systolic flow decreased from 5.9 +/- 5.2 to 2.2 +/- 1.4 (p less than 0.01); diastolic flow increased from 3.1 +/- 1.5 to 4.8 +/- 3.3 (p less than 0.001); and systolic to diastolic ratio decreased from 2.0 +/- 1.2 to 0.7 +/- 0.6 (p less than 0.001). Reversed flow at the end of ventricular systole was present in 9 patients (43%) at stage A and in all patients at stage E. Decreased tricuspid annular motion was noted in all but 1 patient after cardiopulmonary bypass. No patient presented significant tricuspid regurgitation at any stage. In conclusion, the significant change in the pattern of systemic venous return after open heart surgery is not due to opening of the chest wall or parietal pericardium, or to tricuspid regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the postoperative blood flow waveforms of the bypassing grafts in patients following minimally invasive direct coronary artery bypass

PURPOSE: To use Doppler ultrasound velocimetry to detect and compare the postoperative flow characteristics of the bypassing grafts in patients following minimally invasive direct coronary artery bypass surgery (MIDCAB). MATERIALS AND METHODS: From January 1997 to June 1999, 34 patients underwent MIDCAB with the left internal thoracic artery (LITA) to the left anterior descending coronary artery (LAD) [n = 23], with the right gastroepiploic artery (RGEA) to the right posterior descending artery (RPD) [n = 3], or with the LITA with a saphenous vein graft extension to the LAD (n = 6), the diagonal coronary artery (n = 1), or the right acute coronary artery (n = 1). There were two patients with LITA to the LAD and RGEA to the RPD. Patients underwent MIDCAB due to coronary artery stenosis (100% occlusion, n = 10; 90 to 99% stenosis, n = 18; < 90% stenosis, n = 5) or unsuccessful percutaneous transcoronary angioplasty with dissection (n = 1). All patients underwent flow velocity measurement by Doppler ultrasound velocimetry in the immediate postoperative period, and at 6-month and 12-month intervals; graft flows were quantified based on Doppler velocimetric data. RESULTS: The results showed that in a patient with a totally occluded LAD or RPD, typical biphasic velocity waveforms were consistently observed. However, a delayed diastolic wave was noted in RGEA grafts. In patients with less-occluded stenotic lesions or with strong back flows, the flow velocity patterns showed biphasic waveforms but systolic reversal was observed in the area closest to the anastomotic site. CONCLUSION: The presence of an LAD or RPD stenosis proximal to the anastomotic site significantly affects the LITA or RGEA graft flow volume. The biphasic flow pattern proves that an LITA or RGEA graft transports the blood primarily to coronary arteries during the diastolic phase.     

Myocardial Revascularization for the Elderly: Current Options, Role of Off-pump Coronary Artery Bypass Grafting and Outcomes

The increase in life expectancy has confronted cardiac surgery with a rapidly growing population of elderly patients requiring surgical myocardial revascularization. Recent advances in surgical and anesthetic techniques and improvements in postoperative care have made coronary artery bypass grafting an established therapeutic option for the treatment of coronary artery disease in this group of patients. However, conventional coronary artery bypass grafting on cardiopulmonary bypass is associated with significant risk and related morbidity and mortality in the elderly. In recent years off-pump coronary artery bypass grafting has emerged as a safe and less invasive strategy for surgical myocardial revascularization. Off-pump coronary artery bypass grafting by avoiding the deleterious effects of cardiopulmonary bypass can offer potential benefits to elderly patients requiring surgical myocardial revascularization. This review article provides an overview of the age-related cardiovascular changes, epidemiology of coronary artery disease in the elderly and focuses on outcomes of surgical myocardial revascularization with special emphasis on the impact of off-pump coronary artery bypass surgery in the elderly.     

序贯桥终末端与细小靶冠状动脉侧侧和端侧吻合的疗效对比

目的:评估不停跳冠状动脉旁路移植术中,分别采用侧侧吻合与端侧吻合方式缝合大隐静脉序贯桥终末端与细小靶冠状动脉的疗效。方法:回顾性分析2012年10月至2013年4月,行不停跳冠状动脉旁路移植术且终末靶冠状动脉细小的患者共89例。其中37例患者使用侧侧吻合术,即采用侧侧吻合方法缝合大隐静脉序贯桥终末端与靶冠状动脉;52例患者使用端侧吻合术,即将大隐静脉序贯桥终末端与靶冠状动脉进行端侧吻合。术中监测桥血管流量及搏动指数,术后6个月复查超声心动图、心电图等指标,以评估手术疗效。术后1年行双源CT冠状动脉造影检查,观察终末桥血管的通畅情况。结果:两组术中终末桥血管流量分别为[(17.32±6.18)vs.(14.15±5.09)mL/min,P0.05],搏动指数分别为[(2.50±1.08)vs.(3.47±0.74),P0.05]。两组患者在围术期内均无低心排出量综合征(低心排)、恶性心律失常及心肌梗死等不良事件发生。术后6个月复查超声心动图,提示两组患者心功能均较术前改善,但两组之间差异无统计学意义(P0.05)。术后随访1年时侧侧吻合组患者均无心绞痛发作,端侧吻合组有9例患者再发心绞痛。双源CT冠状动脉造影提示:侧侧吻合组中终末桥血管均保持通畅,而端侧吻合组中8例患者的终末桥血管再狭窄(P0.05)。随访截至2014年1月底,平均随访时间为(10.7±2.5)个月,患者随访率为100%,存活率为100%。结论:采用侧侧吻合术缝合大隐静脉序贯桥终末端与细小靶冠状动脉,可改善终末桥血管的通畅性。     

Atrial fibrillation after minimally invasive direct coronary artery bypass surgery

OBJECTIVES: The study compared the adjusted risk for developing atrial fibrillation (AF) after minimally invasive direct coronary artery bypass surgery (MIDCAB) and coronary artery bypass graft surgery (CABG). BACKGROUND: Atrial fibrillation results in increased morbidity and delays hospital discharge after CABG. Recently, MIDCAB has been explored as an alternative to CABG. Because of differences in surgical approach between the two procedures, the incidence of AF may differ. METHODS: Randomly selected patients undergoing CABG and MIDCAB were examined. Baseline variables and postoperative course were recorded through review of medical record data. RESULTS: The MIDCAB patients were younger than CABG patients (64+/-12 vs. 67+/-10, p<0.04) and had less extensive coronary artery disease (53% of MIDCAB vs. 3% of CABG had single-vessel disease, while 15% of MIDCAB vs. 69% of CABG had triple-vessel disease, p<0.001 for overall group comparisons). No other differences in clinical or treatment data were noted. Postoperative AF occurred less often after MIDCAB (23% vs. 39%, p = 0.02). Other significant factors associated with postoperative AF included age (p = 0.0024), prior AF (p = 0.0007), left main disease (p = 0.01), number of vessels bypassed (p = 0.009), absence of postoperative beta-blocker therapy (p = 0.0001), and a serious postoperative complication (p = 0.0018). Because of differences between CABG and MIDCAB patients, multivariate logistic analysis was performed to determine independent predictors of postoperative AF. The type of surgery (CABG vs. MIDCAB) was no longer a significant predictor of postoperative AF (estimated relative risk for AF in CABG vs. MIDCAB patients: 1.57, 95% confidence interval (0.82-2.52). CONCLUSIONS: Although AF appears to be less common after MIDCAB than after CABG, the lower incidence is due to different clinical characteristics of patients undergoing these procedures.     

Hybrid revascularization using percutaneous coronary intervention and robotically assisted minimally invasive direct coronary artery bypass surgery

Hybrid revascularization (HR) combines staged percutaneous coronary intervention (PCI) on stenoses in the non-left anterior descending (LAD) territories with minimally invasive direct coronary artery bypass (MIDCAB) using the left internal thoracic artery (LITA) to the LAD. The LITA-to-LAD graft, which has a 5-year patency rate of 95%, is the major determinant of the long-term survival for patients. Thus, HR aims to perform full revascularization without compromising the survival advantage of the LITA-to-LAD graft, while preserving the minimally invasive advantages associated with the percutaneous treatment of symptomatic coronary stenoses. We investigated whether HR was a valid alternative to conventional coronary artery bypass graft surgery in patients with multivessel coronary artery disease. We also present our early experiences with HR using a combined approach of advanced PCI and robotically-assisted MIDCAB.     

Intra-operative contrast echocardiography in coronary artery disease.

Intra-operative echocardiography is becoming a reference standard for the evaluation of the results of cardiac surgery. Myocardial contrast echocardiography has been recently introduced to study regional myocardial blood flow and cardioplegia distribution in patients undergoing coronary artery surgery. It can be used in three different stages: before cardiopulmonary bypass, to identify the most hypoperfused myocardial segments; during cardioplegic arrest, to check the adequacy of myocardial protection; postoperatively, to assess graft patency. The priority in revascularization can be assigned according to the regional perfusion pattern, which depends not only on coronary artery narrowing, but also on the extent of collateral circulation. The distribution of cardioplegia to the myocardium can be monitored in real time with clear identification of poorly protected myocardial segments. The injection in the graft after weaning from cardiopulmonary bypass allows assessment of graft patency and measurement of the 'area at risk' for graft occlusion. In conclusion, the information obtained in the operating theatre by myocardial contrast echocardiography is original and promises to have a significant impact on surgical strategy. Implementation of the ultrasonic equipment to obtain quantitative on-line data on myocardial blood flow is desirable.     

Assessment of left internal mammary artery graft patency by transthoracic Doppler echocardiography

BACKGROUND: The successful application of noninvasive Doppler spectrum analysis has been reported for the hemodynamic assessment of LIMA graft after myocardial revascularization. HYPOTHESIS: The objective of this study was to assess the utility of transthoracic Doppler echocardiography (TTE) in providing information on LIMA flow in patients after coronary artery bypass graft surgery. METHODS: In all, 22 patients (aged 62 +/- 8 years) with LIMA graft to the left anterior descending (LAD) coronary artery who underwent coronary angiography were assessed using high-frequency (5 MHz) transthoracic Doppler echocardiography. They were compared with 25 patients with angina (control group A, aged 59 +/- 12 years), in whom an ungrafted LIMA was assessed, and with 17 patients (control group B, aged 59 +/- 9 years) with angiographically normal coronary arteries, in whom the LAD was assessed. RESULTS: A biphasic pattern (systolic and diastolic) was recorded in all cases. In 14 patients with a normal graft or < 70% stenosis (Group 1) and in control group B, blood flow was maximal during diastole. In eight patients with severe graft stenosis > 70% (Group 2) and control group B, blood flow was maximal during systole, with low diastolic flow. The diastolic fraction of the velocity time integrals was 0.81 +/- 0.11 for Group 1 and 0.25 +/-0.06 for Group 2 (p < 0.05). A diastolic velocity time integral fraction < 0.5 predicted > 70% stenosis with a sensitivity and specificity of 100%. The ratio of systolic/diastolic peak velocities was 0.61 +/- 0.31 for Group 1 and 3.21 +/- 0.49 for Group 2 (p < 0.05). A systolic/diastolic peak velocity > 1 predicted stenosis > 70% with a sensitivity and specificity of 100 and 90%, respectively. CONCLUSIONS: High-frequency TTE is a useful noninvasive method for detecting LIMA graft blood flow. Severe graft stenoses exhibited Doppler velocity patterns, which were different from those of patent grafts, or grafts with moderate stenoses.     

Hybrid-Verfahren zur Myokardrevaskularisation: Stellenwert der Kombination von minimal-invasiver Bypasstechnik (MIDCAB) mit interventioneller Therapie (PTCA)

BACKGROUND: Minimally invasive direct coronary artery bypass (MIDCAB) grafting without cardiopulmonary bypass (CPB) through an anterolateral minithoracotomy has become a promising therapeutical option especially in multimorbid, elderly and reoperative patients with single vessel disease. However, this procedure precludes complete revascularization in multivessel disease because the minithoracotomy limits the surgical access either to anterior or lateral or posterior vessels of the beating heart. To expand the benefits of the MIDCAB concept to patients with multivessel disease, new interdisciplinary approaches have recently been introduced. METHODS: Since December 1996, 26 patients (21 male, 5 female, mean age 56.6 +/- 18.8 years) underwent a "hybrid" revascularization performed as a primary MIDCAB procedure for grafting of the left anterior descending artery (LAD) with the left internal mammary artery (LIMA) followed by staged angioplasty and stenting of additional coronary lesions. RESULTS: After MIDCAB grafting, the postoperative course was uneventful in all patients. Coronary re-angiography after a median of 7 days revealed patent and functioning LIMA grafts in all patients. Applying subsequent percutaneous transluminal coronary angioplasty (PTCA) and occasional stenting (n = 8), a total of 31 lesions were treated successfully. Procedure related complications did not occur. All patients remained angina-free and no stress electrocardiographic changes were recorded. CONCLUSION: Our preliminary results of a "hybrid" approach to myocardial revascularization suggest that this concept is a safe and effective approach of complete revascularization for selected patients with multivessel involvement. Especially elderly and reoperative patients with significant comorbidity may benefit from hybrid procedures avoiding cardiopulmonary bypass and midsternotomy.     

Pericardial effusion after cardiac surgery: incidence, site, size, and haemodynamic consequences.

OBJECTIVE--To evaluate the incidence, characteristics, and haemodynamic consequences of pericardial effusion after cardiac surgery. DESIGN--Clinical, echocardiographic, and Doppler evaluations before and 8 days after cardiac surgery; with echocardiographic and Doppler follow up of patients with moderate or large pericardial effusion after operation. SETTING--Patients undergoing cardiac surgery at a tertiary centre. PATIENTS--803 consecutive patients who had coronary artery bypass grafting (430), valve replacement (330), and other types of surgery (43). 23 were excluded because of early reoperation. MAIN OUTCOME MEASURES--Size and site of pericardial effusion evaluated by cross sectional echocardiography and signs of cardiac tamponade detected by ultrasound (right atrial and ventricular diastolic collapse, left ventricular diastolic collapse, distension of the inferior vena cava), and Doppler echocardiography (inspiratory decrease of aortic and mitral flow velocities). RESULTS--Pericardial effusion was detected in 498 (64%) of 780 patients and was more often associated with coronary artery bypass grafting than with valve replacement or other types of surgery; it was small in 68.4%, moderate in 29.8%, and large in 1.6%. Loculated effusions (57.8%) were more frequent than diffuse ones (42.2%). The size and site of effusion were related to the type of surgery. None of the small pericardial effusions increased in size; the amount of fluid decreased within a month in most patients with moderate effusion and in a few (7 patients) developed into a large effusion and cardiac tamponade. 15 individuals (1.9%) had cardiac tamponade; this event was significantly more common after valve replacement (12 patients) than after coronary artery bypass grafting (2 patients) or other types of surgery (1 patient after pulmonary embolectomy). In patients with cardiac tamponade aortic and mitral flow velocities invariably decreased during inspiration; the echocardiographic signs were less reliable. CONCLUSIONS--Pericardial effusion after cardiac surgery is common and its size and site are related to the type of surgery. Cardiac tamponade is rare and is more common in patients receiving oral anticoagulants. Echo-Doppler imaging is useful for the evaluation of pericardial fluid accumulations after cardiac surgery. It can identify effusions that herald cardiac tamponade.     

Should use of the internal thoracic artery be avoided under conditions of low free flow? Postoperative hemodynamic assessment using pulsed Doppler echocardiography.

There are cases in which it is thought advisable to avoid the use of the left internal thoracic artery (LITA) in coronary artery bypass grafting (CABG) due to its low free flow (FF). However, even though the LITA flow is very low, anastomosis without any further maneuvers intraluminally is recommended. The present study investigated the clinical results of CABG, using a LITA with low FF. The 60 cases of CABG were divided into 2 groups: (i) Group L (n = 23), in which LITA FF was less than 20 ml/min; and (ii) Group H (n = 37) in which it was more than 20 ml/min. A comparative study on the basis of coronary angiography and pulsed Doppler echocardiography was performed. In both groups, no LITA graft occlusion was identified, and the 'string sign' was also absent. In the LITA blood waveform, all cases exhibited a biphasic pattern with a higher mid-diastolic and a lower end-systolic component. There were no significant differences in the LITA flow diastolic peak velocity, velocity time integrals and the diastolic/systolic peak velocity ratios. These results suggest that the LITA can be used for CABG even when the free flow is less than 20 ml/min.