Effects of intravenous triiodothyronine during coronary artery bypass surgery

A prospective randomized and double-blind study was performed to evaluate whether perioperative triiodothyronine administration has any effect on cardiovascular performance after coronary artery bypass surgery. Sixty patients were assigned to 2 groups of 30 each. When crossclamping ended, group A received an intravenous bolus of triiodothyronine, followed by infusion for 6 hours. Group B received a placebo. Serum triiodothyronine levels and hemo-dynamic parameters were serially measured. Mean postoperative cardiac index was slightly, but not significantly, higher in group A, whereas systemic vascular resistance was significantly lower in group A. Compared with preoperative values, serum triiodothyronine levels dropped significantly in group B at the end of cardiopulmonary bypass and remained low 12 hours postoperatively, while levels rose significantly in group A. No significant differences were detected between the groups in the incidence of arrhythmia, the need for inotropic support, intensive care unit stay, mortality, and morbidity. Perioperative administration of triiodothyronine increased cardiac output slightly and decreased systemic vascular resistance, but it had no effect on operative outcome. Routine use after coronary surgery is thus not recommended.     

Hemodynamic effects of a lorazepam-fentanyl anesthetic induction for coronary artery bypass surgery

Previous anesthetic induction techniques using the combination of a benzodiazepine (midazolam or diazepam) and fentanyl have been reported to produce marked hypotension. In this study, anesthesia was induced with a combination of lorazepam and fentanylin in patients undergoing coronary artery bypass graft surgery. In 10 patients, anesthesia was induced using an exponentially declining continuous infusion of lorazepam equivalent to a total infused dose of 0.1 mg/kg over 15 minutes, which was supplemented at 10 minutes by fentanyl, 75 μg/kg, given as an infusion over 5 minutes. In 8 additional patients, anesthesia was induced with an exponentially declining infusion of fentanyl to a total dose of 75 μg/kg over 15 minutes, which was supplemented at 10 minutes by lorazepam, 0.1 mg/kg, given as an infusion over 5 minutes. Hemodynamics were recorded during a 20-minute observation period. One patient in each group required treatment for bradycardia during the initial drug infusion (before the second drug was added). Four additional patients in the group receiving lorazepam followed by fentanyl required treatment for bradycardia or hypotension within 10 minutes of the beginning of the fentanyl infusion. When an infusion of lorazepam was added to the fentanyl infusion, hemodynamics remained stable; however, the reverse order produced a high level of bradycardia and hypotension.     

冠状动脉搭桥与冠脉介入治疗的比较

冠状动脉旁路移植术（CABG）和经皮冠状动脉介入术（PCI）是目前治疗冠状动脉狭窄的两种主要治疗方法。CABG是半个世纪以来治疗冠心病经典手段之一,近年来由于对桥血管的选择和保护、全动脉再血管化等的重视,其近远期治疗效果明显提高。随着介入技术的发展,这项技术以其微创、安全、易于被患者所接受等特点,适应证不断扩大。本文就近年来CABG和PCI在治疗冠心病方面的发展和优势作一综述。     

Epicardial coronary artery constriction with intravenous ethanol

Although in vitro studies have demonstrated ethanol-induced coronary artery constriction, in vivo reports suggest an ethanol-related coronary dilator effect with increases in coronary blood flow. The principal difference in these studies is the demonstration of epicardial coronary constriction with ethanol, while dilation is described only in resistance vessels. Clinical studies have noted evidence of myocardial ischemia following ethanol ingestion in patients with coronary artery disease, suggesting ethanol-related constriction of diseased epicardial coronary arteries. This study hypothesized that intravenous ethanol would constrict canine epicardial coronary arteries while producing arteriolar resistance vessel dilatation. Ten closed-chest mongrel dogs weighing 24 +/- 1 kg (mean +/- SEM) were given 8 g of ethanol intravenously over 30 min. Left anterior descending and circumflex proximal artery diameters were measured by quantitative coronary angiography; myocardial flow was measured by Xenon washout, and myocardial flow distribution was measured with radioactive microspheres. Baseline proximal left anterior descending and circumflex artery areas were 6.3 +/- 0.5 and 5.8 +/- 0.4 mm2, respectively. Up to 30% left anterior descending and circumflex proximal artery narrowing was noted at 60 and 90 min following ethanol infusion. The constriction was reversed with nitroglycerin. There was a decrease in left anterior descending artery flow but no change in circumflex artery flow at 60 min. Blood ethanol level varied from 520 micrograms/ml initially to 205 micrograms/ml 90 min after the infusion terminated (intoxication = 1500 micrograms/ml). These data suggest that ethanol has significant vasoconstrictor action in vivo on epicardial coronary arteries.     

Efficacy and safety of intravenous tocainide compared with intravenous lidocaine for acute ventricular arrhythmias immediately after cardiac surgery

In this double-blind parallel study, 99 patients with acute ventricular tachyarrhythmias after open-heart surgery were given either tocainide (50 patients) or lidocaine (49 patients) intravenously as 2 bolus injections 15 minutes apart, plus a fixed-rate infusion that started at the first bolus. If needed, a third bolus was administered and simultaneously the infusion rate was doubled. The boluses and initial infusion rate for tocainide treatment were, respectively, 250, 250 and 125 mg and 1.04 mg/min, and for lidocaine treatment, 100, 50 and 50 mg and 2.08 mg/min. When efficacy was defined as 80% or greater reduction in single ventricular premature complexes (VPCs) or complete abolition of ventricular couplets or ventricular tachycardia, no difference in efficacy between the 2 treatments was found by bedside electrocardiographic monitoring. By computer analysis of 24-hour taped electrocardiograms and a regression analysis of the proportion of patients responding favorably to treatment, it was estimated that an 80% or greater reduction of single VPCs occurred in 55% of patients during tocainide treatment and in 48% of patients during lidocaine treatment; abolition of couplets occurred in 74% and 68% of patients, respectively; and abolition of ventricular tachycardia in 87% and 73% of patients, respectively. These treatment-related differences were different (p less than 0.004). Adverse reactions occurred in 5 patients (10%) given tocainide (hypotension in 4; junctional rhythm in 1 patient; and nausea-vomiting in 1) and led to discontinuation of treatment in 3 patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anesthesia for coronary artery surgery

Anesthesia for coronary artery bypass graft surgery continues to evolve in concert with changing epidemiology, advances in technology and pharmacology, and refinement in technique. The profile of the cardiac surgical patient is increasingly characterized by factors such as advanced age, reoperation, combination procedures, complications of acute intervention, and more complex disease. Preoperative risk factor assessment offers a means of strategic planning and intervention. Choice of anesthetic agents, muscle relaxants, and anti-ischemic medications affects both perioperative management and long-term outcome. Transesophageal echocardiography and ST segment monitoring are being applied more broadly. Advances have been made in managing postoperative blood loss. As in other areas of medicine, economic issues have become important considerations in anesthesia for the cardiac surgical patient.     

Sufentanil-midazolam anesthesia for coronary artery surgery

The combination of benzodiazepines and high-dose narcotics has been reported to produce hypotension in patients undergoing coronary artery surgery. This study was performed to evaluate the cardiovascular effects of lower doses of the narcotic sufentanil administered with the benzodiazepine midazolam. Thirty adult patients with good ventricular function undergoing elective coronary revascularization received sufentanil, 2.5 μg/kg, and midazolam, 0.1 mg/kg, followed by infusions of sufentanil; 0.7 to 1.5 μg/kg/h, and midazolam, 0.07 to 0.15 mg/kg/h. Overall, stable hemodynamics were achieved before and after cardiopulmonary bypass (CPB). Patients who were not receiving preoperative β-adrenergic blockade (n = 15) had increases from baseline heart rate and rate-pressure product after sternotomy, during aortic dissection, and after CPB that were not clinically significant. Five patients developed hypertension (increases greater than 20% over the baseline value), which was controlled with additional sufentanil or a vasodilator. Hypertension requiring vasodilator therapy did not occur in patients taking β-adrenergic blockers. Blood pressure decreases exceeding 20% of the baseline value did not occur. Two of 15 patients receiving β-blockers, versus 3 of 15 not receiving β-blockers, developed ischemic electrocardiographic changes before CPB (NS): one of these patients without β-blockade had a postoperative myocardial infarction. The results of this study show that the infusion of low doses of sufentanil with midazolam provides a hemodynamically safe and stable anesthetic for coronary artery surgery and avoids the hypotension seen when a high-dose narcotic is combined with a benzodiazepine.     

Valvular and coronary artery surgery

This brief review supplements recent extensive discussion of valvular and coronary artery surgery in this journal. It includes 1) ultrasonic decalcifications of stenotic aortic valves, a technique once more found wanting because of induced aortic incompetence; 2) the concept of prosthesis-specific anticoagulation, adjusting the level of anticoagulant control for individual prosthetic valves to minimize thromboembolic and hemorrhagic complications; 3) the use of homograft aortic roots to treat aortic prosthetic valve endocarditis; and 4) a new approach to the repair of postinfarction ventricular septal defects, supported by excellent results.     

Robotics and coronary artery surgery

Significant progress in cardiac surgery, and specifically the surgical management of coronary artery disease, has been due in large part to enabling technology. Robotic systems have been recently developed and refined for use in cardiac surgery to facilitate, among other procedures, a totally endoscopic approach to coronary artery bypass surgery. These systems enhance precision through endoscopic approaches by specifically addressing the inherent limitations of conventional endoscopic coronary microsurgical instrumentation via computerized, digital interface, telemanipulation technology. With a combined experience of 125 patients, several groups have independently demonstrated the clinical feasibility of totally endoscopic coronary artery bypass with two commercially available robotic telemanipulation systems. Additional enabling technology is needed to overcome the challenges currently limiting development and widespread application of totally endoscopic off-pump multivessel coronary artery bypass surgery.     

Thyrotoxicosis with coronary spasm that required coronary artery bypass surgery

We describe a 47-year-old woman with severe coronary vasospasm induced by hyperthyroidism. The patient complained of anginal chest pain without specific characteristics of thyrotoxicosis. Coronary arteriography was performed and revealed 90% stenosis of both the left and right coronary os. She was treated with emergent coronary artery bypass graft surgery. Postoperatively, she exhibited a comatose mentality. Severe thyrotoxicosis was indicated on thyroid function tests and thyrotoxic storm was diagnosed. Nineteen days after the surgery and following the initiation of propylthiouracil treatment, coronary arteriography revealed entirely normal coronary arteries.     

Comparison of coronary artery bypass surgery with percutaneous coronary intervention with drug-eluting stents for unprotected left main coronary artery disease.

OBJECTIVES: This study evaluated the clinical outcomes of consecutive, selected patients treated with coronary artery bypass graft (CABG) surgery or percutaneous coronary intervention (PCI) with drug-eluting stents (DES) for unprotected left main coronary artery (ULMCA) disease. BACKGROUND: Although recent data suggest that PCI with DES provides better clinical outcomes compared to bare-metal stenting for ULMCA disease, there is a paucity of data comparing PCI with DES to CABG. METHODS: Since April 2003, when DES first became available at our institution, 123 patients underwent CABG, and 50 patients underwent PCI with DES for ULMCA disease. RESULTS: High-risk patients (Parsonnet score >15) comprised 46% of the CABG group and 64% of the PCI group (p = 0.04). The 30-day major adverse cardiac and cerebrovascular event (MACCE) rate for CABG and PCI was 17% and 2% (p < 0.01), respectively. The mean follow-up was 6.7 +/- 6.2 months in the CABG group and 5.6 +/- 3.9 months in the PCI group (p = 0.26). The estimated MACCE-free survival at six months and one year was 83% and 75% in the CABG group versus 89% and 83% in the PCI group (p = 0.20). By multivariable Cox regression, Parsonnet score, diabetes, and CABG were independent predictors of MACCE. CONCLUSIONS: Despite a higher percentage of high-risk patients, PCI with DES for ULMCA disease was not associated with an increase in immediate or medium-term complications compared with CABG. Our data suggest that a randomized comparison between the two revascularization strategies for ULMCA may be warranted.     

心脏直视手术前颈动脉支架术的初步探讨

目的 评估心脏疾病合并严重颈动脉狭窄患者于心脏直视手术前行颈动脉支架术预防围手术期缺血性卒中的有效性和安全性.方法 前瞻性队列研究,对心脏疾病合并严重颈动脉狭窄患者于心脏直视手术前行颈动脉支架术,评估颈动脉支架术至心脏直视术后30 d的终点事件(卒中、心肌梗死和死亡).结果 自2005年1月至2007年12月,本研究共连续入选42例患者.颈动脉支架技术成功率100%.远端栓塞防护装置使用率为97.6%(41/42).心脏直视手术包括:冠状动脉旁路移植术36例(85.7%),冠状动脉旁路移植术加瓣膜置换术5例(11.9%),瓣膜置换术1例(2.4%).自颈动脉支架术至心脏直视术后30 d的卒中率为2.4%(1/42),心肌梗死率为0%,死亡率为0%.结论 这一小样本前瞻性队列研究表明,心脏直视手术前行颈动脉支架术预防围手术期缺血性卒中安全有效,优于文献报告的分期颈动脉内膜剥脱术的结果,但由于本研究样本量小,需进一步研究验证.     

Hemodynamic and coronary effects of intravenous labetalol in coronary artery disease

Labetalol, an alpha and beta receptor blocking agent, was evaluated in 11 patients with documented coronary artery disease and stable angina. The mean dose of labetalol was 1.5 (range 1 to 2) mg/kg. Cardiovascular effects began within 1 minute after injection and were maximal within 10 minutes. Mean arterial pressure decreased from 105 ± 13 to 81 ± 10 mm Hg (p < 0.0001), heart rate from 70 ± 10 to 66 ± 7 beats/min (p < 0.05) and the pressure-rate product from 10,322 ± 2,344 to 7,717 ± 1,650 (p < 0.001). Cardiac output and pulmonary wedge pressure did not change significantly. Mean pulmonary arterial pressure decreased from 20 ± 3 to 16 ± 2 mm Hg (p < 0.005). Systemic and pulmonary resistances also decreased significantly (p < 0.0001 andp < 0.01, respectively). Coronary sinus flow increased from 107 ± 26 to 118 ± 25 ml/min (p < 0.01) and coronary vascular resistance decreased from 1.0 ± 0.2 to 0.77 ± 0.1 mm Hg/ml per min (p < 0.001).Labetalol may be a useful adjunct in the treatment of angina not only because it diminishes myocardial oxygen requirements but also because it improves coronary hemodynamics. Thus, labetalol appears to have some advantage compared with the usual beta blocking agents with their potentially detrimental effects on coronary hemodynamics.