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.

Sudden development of intraoperative left ventricular outflow obstruction: differential and mechanism. An intraoperative two-dimensional echocardiographic study.

Systolic anterior motion (SAM) of the mitral valve, once considered to be pathognomonic of hypertrophic cardiomyopathy, has been reported in the absence of asymmetric septal hypertrophy. Of the 1,000 open heart operations performed with intraoperative two-dimensional epicardial echocardiography monitoring, four patients developed intraoperative dynamic left ventricular outflow obstruction associated with systolic anterior motion of the mitral valve that was not present preoperatively: three cases of mitral valve annuloplasty with Carpentier ring insertion and one of coronary artery bypass grafting. Though no patient had asymmetric septal hypertrophy or echocardiographic evidence of outflow obstruction by either preoperative cardiac catheterization or echocardiography, intraoperative two-dimensional epicardial echocardiography revealed SAM, and hyperdynamic left ventricles with three of these patients having documented left ventricular outflow tract gradients causing hemodynamic compromise. (Case 4 was hemodynamically stable following mitral valve repair, but had SAM and significant residual mitral regurgitation [MR] requiring reinstitution of cardiopulmonary bypass and re-repair). Measurement of mitral annular dimension demonstrated a normal decrease in size from diastole to systole in control operative subjects but not in the patients who developed outflow obstruction. The pathophysiology, treatment, and role of intraoperative echocardiography of dynamic left ventricular outflow tract obstruction are discussed.

Intraoperative evaluation of valvular regurgitation: comparison of echocardiographic techniques.

Intraoperative echocardiography provides information on cardiac structure and function that is unobtainable from routine monitoring modalities. Intraoperative imaging can be performed from the epicardial and/or transesophageal approach, and with the addition of contrast and/or color flow Doppler mapping, blood flow characteristics within the cardiac chambers can be visualized. The relative severity of regurgitation can be assessed before and after valvular surgery, and before the patient leaves the operating room, thereby facilitating successful valve repair or replacement. Surgeon preference, equipment availability, and valvular pathology will determine which technique will be utilized.

Open heart surgery in patients in the eighth and ninth decades of life.

One hundred fifty-one patients aged 70-89 years underwent a variety of open heart surgical procedures during a period of 1 year. We divided these patients into two groups: Group A was comprised of 127 patients between 70 and 79 years of age. In group B, 24 patients were between 80 and 89 years of age. These patients underwent elective open heart surgery. Information was retrieved retrospectively from the computerized data pool of the cardiothoracic registry in our institution. Statistical analysis in these two groups revealed no significant differences in any of the evaluated factors. We concluded that age should not be a contraindication for cardiac operations.

Quantitative HPLC analysis of human plaque proteins in coronary and thoracic aorta arteries.

Quantitative HPLC analysis of saline-soluble proteins obtained from human coronary and thoracic aorta plaque and from whole internal mammary artery were performed. Protein extracts were characterized by anion exchange and reverse-phase HPLC and the integrated chromatographs revealed significant differences in both peak retention times and areas for protein species from coronary artery compared to thoracic aorta artery plaque. Coronary artery plaque proteins possessed a high degree of cationic charge and polarity compared to those present in thoracic aorta plaque and normal mammary artery. This suggests that specific protein markers may be expressed in plaque of different anatomical origin, and that the processing of protein may be distinct to plaque sites. In contrast, characterization of molecular weight by gel electrophoresis resolved no major differences between plaque types. These findings indicate that proteins in human plaque lesions of different anatomical origin can be resolved by HPLC methodology and that they exhibit different charge and polarity. Such an HPLC approach may prove useful in the quantitative identification and ultimate isolation of specific protein markers present in plaque during atherogenesis, and in the study of mechanisms of protein involvement in plaque formation.

A comparison of hemodynamic indices derived by invasive monitoring and two-dimensional echocardiography.

Intraoperative two-dimensional echocardiography (2D-echo) is useful for monitoring global and regional left ventricular function. The 2D-echo view most frequently utilized during intraoperative monitoring is the short-axis view at the level of the papillary muscles. To determine whether hemodynamic data can be derived from this single 2D-echo short-axis view, 12 patients undergoing coronary artery bypass grafting (CABG) were studied. All patients had normal left-ventricular function preoperatively (ejection fraction = 64% +/- 12%). Echo-data were obtained before and after cardiopulmonary bypass (CPB) by epicardial placement of a 5 MHz echo-transducer. The correlation between thermodilution and echo-derived cardiac indices was good (r = 0.8), and not significantly different from the correlation between stroke indices (r = 0.68). A strong positive correlation was established between end-diastolic volume index and echo cardiac index (CIE) (r = 0.93 before CPB; r = 0.91 after CPB) and end-diastolic area index and CIE (r = 0.94 before CPB; r = 0.91 after CPB). The pulmonary capillary wedge pressure was not a determinant of cardiac index before or after cardiopulmonary bypass. No correlation was observed between systemic vascular resistance and echo-derived wall stress. These findings demonstrate that, in patients with good left-ventricular function undergoing CABG surgery, 2D-echo provides a better index of left-ventricular preload than conventional invasive hemodynamic monitoring.

Absence of prostaglandin changes associated with protamine administration in patients with pulmonary hypertension.

In patients with pre-existing pulmonary hypertension, severe pulmonary vasoconstriction has been observed following protamine administration. Thromboxane A2, a potent vasoconstrictor, is capable of producing increases in pulmonary vascular resistance, and animal studies suggest that heparin-protamine complexes stimulate thromboxane A2 synthesis. This study assessed the effect of protamine administration on hemodynamics and on plasma thromboxane A2 and its biologic antagonist, prostacyclin, by serial measurement of the stable metabolites, thromboxane B2 and 6-keto-prostaglandin F1 alpha, respectively. Ten adults with pulmonary artery hypertension undergoing elective mitral valve replacement were studied. After termination of cardiopulmonary bypass, baseline hemodynamic measurements were obtained and arterial blood for prostanoid analysis was sampled. Hemodynamic and prostanoid measurements were obtained 5, 10, 15, and 30 minutes after the protamine infusion began. Prostanoid levels were performed by double antibody radio-immunoassay. No significant hemodynamic changes occurred and no significant changes in prostanoid levels were observed. It is concluded that in patients with pulmonary hypertension, heparin-protamine complexes do not consistently raise circulating thromboxane levels, and the relationships among prostanoids, pulmonary hypertension, and systemic hypotension are still not clear.

Mitral valvuloplasty is superior to valve replacement for preservation of left ventricular function: an intraoperative two-dimensional echocardiographic study.

To investigate the mechanism and time of onset of ventricular dysfunction after mitral valve replacement, 18 patients with pure, severe mitral regurgitation (of whom 10 underwent mitral valve repair and 8 standard mitral valve replacement with papillary muscle excision) were studied by intraoperative two-dimensional echocardiography immediately before and immediately after the operative procedure. No patient sustained a perioperative myocardial infarction or had any residual mitral regurgitation. Although preoperative hemodynamics were similar, postoperatively the patients with valve repair had a lower pulmonary capillary wedge pressure than did the patients with valve replacement (8.6 +/- 1.9 versus 14.4 +/- 7.5 mm Hg, p less than 0.04). Although intraoperative echocardiographic ejection fraction fell significantly after mitral valve replacement (0.64 +/- 0.11 to 0.40 +/- 0.09, p less than 0.0001), it was maintained after valve repair (0.44 +/- 0.20 to 0.49 +/- 0.16, p = NS). Additionally, regional myocardial contractile abnormalities in the anterior and posterior septum were detected immediately after the procedure by intraoperative echocardiography in the patients with valve replacement, but not in those with repair. These postoperative regional contractile abnormalities after papillary muscle resection have not been described previously. Resection of the papillary muscles may disrupt the muscle bundle alignment and induce contractile abnormalities remote from the excised muscle. This study demonstrated that significant global and regional ventricular dysfunction develops immediately after removal of the papillary muscles, whereas myocardial contractility is preserved in patients undergoing mitral valve repair. Therefore, with intraoperative echocardiography to assure minimal residual regurgitation, surgeons should attempt to preserve ventricular function by performing mitral valve reconstruction in patients with mitral regurgitation.

Effect of nitroglycerin during hemodynamic estimation of valve orifice in patients with mitral stenosis.

In patients with mitral stenosis, valve orifice calculations using pulmonary capillary wedge pressure as a substitute for left atrial pressure may overestimate the severity of disease. Previous studies have shown that mitral valve area determined from transseptal left atrial pressure measurements exceeds that area derived from pulmonary wedge pressure measurements. This is probably due to pulmonary venoconstriction, which is reversed by nitroglycerin. Nitroglycerin, 0.4 mg, was administered sublingually to 20 patients with mitral valve disease during preoperative cardiac catheterization using the pulmonary capillary wedge pressure as the proximal hydraulic variable. At the time of a peak hypotensive effect, 3 to 5 minutes after nitroglycerin administration, the mean pulmonary capillary wedge pressure decreased from 23 +/- 2 (mean +/- SEM) to 19 +/- 2 mm Hg (p less than 0.005). The mean diastolic transmitral pressure gradient (12.6 +/- 1.2 mm Hg before and 11.5 +/- 1.0 mm Hg after nitroglycerin; p = NS) and cardiac output (4.0 +/- 0.3 to 4.1 +/- 0.3 liters/min; p = NS) did not change significantly. Nevertheless, the hemodynamic mitral orifice area, calculated using the Gorlin formula, increased from 0.8 +/- 0.1 to 1.1 +/- 0.2 cm2 (p less than 0.05). In 12 patients with isolated mitral stenosis, without regurgitation, the mitral valve orifice area after nitroglycerin was 0.4 +/- 0.2 cm2 larger than it was before drug administration (p less than 0.05). Administration of nitroglycerin during evaluation of mitral stenosis eliminates pulmonary venoconstriction, which raises the pulmonary capillary wedge pressure above the left atrial pressure in some patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Extraluminal compression of an aortic graft simulating recoarctation.

Restenosis rarely develops after surgical correction of coarctation of the aorta in adults. Late morbidity is usually related to residual hypertension or progressive aortic valve disease. A patient in whom symptoms and signs of recurrent coarctation developed 19 years after initial graft repair is described. Dehiscence of the original silk suture line was found at operation. Extensive thrombus had produced graft compression. Milder hypertension persisted in the postoperative period despite relief of the aortic obstruction.

Improved surgical approach to cardiac tumors with intraoperative two-dimensional echocardiography.

Intraoperative two-dimensional echocardiography allows visualization of cardiac anatomy and function not possible by other techniques. Although preoperative evaluation by noninvasive methods is usually adequate for diagnosis of cardiac tumors, two-dimensional echocardiography can be beneficial intraoperatively. Intraoperative echocardiography provides an accurate evaluation of cardiac anatomy, extent of tumor invasion, valvular function and the possible presence of intracardiac communications. Importantly, following tumor resection and a complex operative reconstructive procedure, the echocardiogram can confirm complete intracardiac tumor excision, evaluate post-repair ventricular function, and exclude an intracardiac communication or valvular insufficiency.

Validation of quantitative intraoperative transesophageal echocardiography.

Transesophageal echocardiography (TEE) is a new monitoring technique that images the heart and provides information on regional wall motion and left ventricular filling. However, despite its potential for inaccuracy due to its retrocardiac position and angulation, TEE has not been validated by another imaging technique. Using direct on-heart echocardiography (OHE) as a standard, the authors evaluated the ability of TEE to measure accurately left ventricular end-diastolic area (EDa), end-systolic area (ESa), and ejection fraction area (EFa). Ten patients with coronary artery disease without evidence of valvular dysfunction undergoing myocardial revascularization were studied. A Diasonics 3.5 MHz two-dimensional TEE probe was introduced into each patient's esophagus and positioned to obtain a view equivalent to the parasternal short-axis projection. A similar view was obtained by OHE using a sterilely prepared 3 MHz ATL probe placed on either the pericardium or epicardium. In each patient, immediately prior to and after pericardiotomy, both transesophageal and on-heart short-axis views at the level of the papillary muscles were obtained. Using a dedicated Diasonics computer echoanalyzer, EDa and ESa from four consecutive cardiac cycles were outlined with a light pen and averaged. EFa was calculated by the formula EFa = (EDa - ESa)/EDa. Seventeen comparable transesophageal and on-heart echocardiograms were obtained. ESa by TEE correlated well with ESa by OHE (15.13 +/- 9.62 cm2 vs. 14.92 +/- 10.53 cm2; r = 0.94). Similar results were obtained for EDa (27.75 +/- 9.88 cm2 vs. 30.40 +/- 13.99 cm2; r = 0.88) and EFa (0.49 +/- 0.17 vs. 0.54 +/- 0.13; r = 0.92). filling and ejection.

Aortic valvuloplasty for acquired aortic stenosis.

With the advent of reliable prosthetic valves, the number of aortic valvuloplastic procedures performed in adults has decreased significantly. This is in contradistinction to patients with congenital aortic stenosis, in whom aortic valvuloplasty remains the primary approach. Although only a 25% to 50% incidence of long-term clinical improvement has been reported after aortic valvuloplasty for acquired aortic stenosis, long-term success in adults can be predicted only if a valve area of greater than 1.0 cm2 is obtained, and if there is only minimal residual aortic insufficiency. Due to potential prosthetic valve-related complications aortic valvuloplasty was performed in 23 patients (14 women; nine men) with a mean age of 75 years (range 59 to 94). All patients had small aortic roots (20 less than or equal to 19 mm, 3 less than or equal to 21 mm) and a contraindication to anticoagulation. Baseline and postprocedure intraoperative two-dimensional contrast echocardiography was used to image leaflet mobility and the degree of aortic insufficiency. Cardiac outputs and pressure gradients were also recorded to calculate valve area before and after cardiopulmonary bypass. The postrepair gradient (mean 9 +/- 1.4 mm Hg) was significantly less (p = 0) than the prerepair gradient (mean 54 +/- 6.3 mm Hg). The postrepair valve area (mean 1.56 +/- 0.05 cm2) was significantly greater (p = 0) than the prerepair valve area (mean 0.55 +/- 0.05 cm2). Two patients required late reoperation: one for late bacterial endocarditis and one, whose valve area after valvuloplasty increased from 0.71 to only 0.91 cm2, for "restenosis."(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative echocardiography for the evaluation of valvular regurgitation: experience in 263 patients.

Because of the limited orifice size and potential complications associated with prosthetic valves, native valve repair and reconstruction is an attractive surgical alternative. However, significant residual valvular regurgitation, which cannot be reliably detected intraoperatively by current methods, increases postoperative morbidity and mortality. Direct epicardial two-dimensional echocardiography with contrast injections can be applied intraoperatively to rapidly and accurately assess the presence and severity of valvular regurgitation in the baseline and postoperative state. Five milliliters of dextrose or saline are injected into the appropriate cardiac chamber, generating echogenic microbubbles (contrast) that normally exit in an antegrade direction, but reflux retrograde in the presence of valvular regurgitation. In a total of 263 patients who underwent intraoperative contrast echocardiography, 177 mitral, aortic, and tricuspid valves were adequately assessed by preoperative catheterization and results were compared with those of intraoperative contrast echocardiography. The sensitivity and specificity of the intraoperative detection of valvular regurgitation by echocardiography were 0.97 and 0.98, respectively, for all valves, 1.00 and 0.90 for mitral valves, and 0.91 and 1.00 for aortic valves. Moreover, intraoperative contrast echocardiography can also provide quantification of valvular regurgitation. In 120 mitral valves evaluated, the correlation between the degree of regurgitation determined by preoperative ventriculography and by intraoperative contrast echocardiography (both on a scale of 0 to 4+) was 0.93. Importantly, 11 patients who had mitral surgery (eight after mitral valve repair, and three after valve replacement) were identified as having significant postprocedure mitral regurgitation by intraoperative contrast echocardiography only, not by other methods. Additionally, nine patients were found to have significant tricuspid regurgitation by intraoperative contrast echocardiography after mitral surgery and underwent successful tricuspid annuloplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of temperature, mean arterial pressure, and cardiopulmonary bypass flows on somatosensory evoked potential latency in man.

Median nerve somatosensory evoked potentials were recorded in 21 patients undergoing cardiac surgical procedures utilizing cardiopulmonary bypass, in order to establish the effects of hypothermia, reductions in mean arterial pressure, and alterations in cardiopulmonary bypass flows on evoked potential latency. Induction and maintenance of anesthesia with fentanyl caused a significant prolongation of latency of the first cortical peak. Temperature changes were linearly correlated with changes in latency for peaks recorded from Erb's point (r = -0.843, p less than 0.01) and the contralateral cortex (r = 0.843, p less than 0.01). There was no significant effect of mean arterial pressure or cardiopulmonary bypass flow reductions on latencies under the conditions of this study. Our results emphasize the importance of monitoring peripheral and first cortical peak latencies in evaluating somatosensory evoked potentials. It is suggested that peak latency prolongations beyond those predicted by temperature alterations may be indicative of hypoperfusion.

The safety and efficacy of esmolol during myocardial revascularization.

The safety and efficacy of esmolol during high-dose fentanyl anesthesia were studied in 37 patients undergoing coronary artery bypass grafting (CABG). The anesthetic management consisted of fentanyl 75 micrograms/kg, pancuronium 0.15 mg/kg, and O2. To assess the safety of esmolol, it was administered in a double-blind manner to 17 anesthetized patients prior to surgical incision. Infusion of the drug was increased in stepwise fashion to obtain administration rates between 100 and 300 micrograms X kg-1 X min-1. Esmolol produced small but significant increases in pulmonary capillary wedge pressure (PCWP) (8.3 +/- 1.7 to 13.2 +/- 2.0 mmHg) when compared with placebo (10.9 +/- 1.0 to 12.1 +/- 0.6 mmHg) (P less than 0.05). For the other studied parameters (heart rate, mean arterial pressure, central venous pressure, cardiac index, stroke index, left ventricular stroke work index, systemic vascular resistance, and peripheral vascular resistance), no significant differences were observed between esmolol and placebo. To evaluate the efficacy of esmolol, 20 patients were randomly assigned to an esmolol group (n = 11) or a placebo group (n = 9). The study medication was infused from 5 min before induction through initiation of cardiopulmonary bypass. Infusion of esmolol at 200 micrograms X kg-1 X min-1 prevented tachycardia in response to intubation. In the esmolol group the heart rate increased from 63.4 +/- 2.7 to 67.6 +/- 2.9 beats/min after intubation, while in the placebo group it increased from 61.4 +/- 4.3 to 72.4 +/- 3.4 beats/min (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of labetalol on limb haemodynamics in patients following coronary artery bypass graft surgery.

Labetalol is a competitive inhibitor of alpha- and beta-adrenergic receptors and has an antihypertensive action. To determine limb haemodynamic effects, we measured calf blood flow and venous capacitance by venous occlusion plethysmography before and after oral labetalol in 10 patients 3-7 days following coronary bypass surgery. Vascular resistance was calculated as the ratio of mean arterial pressure to arterial flow. The peak effect of labetalol was taken as the point of maximum blood pressure decline, and this interval was selected for evaluation of the limb haemodynamic response. Ninety to 120 min after administration of 100-200 mg of labetalol the mean blood pressure fell from 88 +/- 3 to 79 +/- 3 mm Hg; (P less than 0.005). The mean arterial blood flow registered 5.1 +/- 1.0 ml 100 ml-1 limb tissue min-1 which was not significantly different from the control value of 4.4 +/- 0.8 ml 100 ml-1 limb tissue min-1. The calculated index of limb vascular resistance was not affected by labetalol administration, averaging 37 +/- 12 mm Hg 100-1 ml limb tissue min-1 before labetalol and 30 +/- 11 mm Hg ml-1 100 ml limb tissue min-1 at the time of peak hypotensive effect. There was a slight but statistically significant increment in limb venous volume to 1.9 +/- 0.3 from 1.5 +/- 0.3 ml 100 ml-1 limb tissue (P less than 0.025). Placebo administration produced no consistent changes in blood pressure, arterial blood flow, vascular resistance or venous capacitance.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative two-dimensional echocardiography: new application of an old technique.

Intraoperative two-dimensional echocardiography is a new diagnostic and monitoring technique that provides immediate information, unavailable from routine hemodynamic measurements, on both myocardial and valvular function. The presence and severity of valvular regurgitation can be assessed from the visualized flow pattern of microbubbles generated by an injection of saline solution: reflux flow into the retrograde chamber represents valvular insufficiency. The extent of valvular regurgitation can be determined immediately after conservative valve repair (annuloplasty or commissurotomy) or replacement to avoid the patient's leaving the operating suite with significant but undetected valvular insufficiency. Additionally, intraoperative echocardiography permits rapid evaluation of left ventricular systolic and diastolic volumes and myocardial contractility, thereby facilitating therapeutic interventions in the operating room. It also permits assessment of congenital heart defects and the competency of their repair. Pulsed, continuous and color-flow real time Doppler imaging methods allow further intraoperative definition of stenotic and regurgitant lesions.

Localization of aortic dissection intimal flap by intraoperative two-dimensional echocardiography.

Ascending (type I) aortic dissection carries a high morbidity and mortality. Proper identification of the proximal origin of the dissection and determination of concomitant aortic valve involvement significantly facilitate surgical repair, which may improve survival. In this case, intraoperative two-dimensional echocardiography with contrast injections was used to image the heart and great vessels before and after cardiopulmonary bypass. The proximal origin of the intimal flap of a type I dissection was identified, and primary aortic valve disease was excluded. Postprocedure intraoperative echocardiography demonstrated that the site of repair was imaged and that aortic regurgitation was absent. Intraoperative contrast two-dimensional echocardiography may be a valuable new tool to provide information otherwise unavailable by routine techniques.