Diazepam prevents some adverse effects of succinylcholine.

Neuromuscular, circulatory, and adverse effects of intravenous succinylcholine (SCh), mg/kg, were compared in 3 groups of 40 patients each. Group I served as control; group II received diazepam, 0.05 mg/kg, 5 min before SCh; and group III was given d-tubocurarine (d-Tc), 0.05 mg/kg, for pretreatment. Diazepam pretreatment prevented muscle fasciculations, increases in serum potassium (K+) and creatinine phosphokinase (CPK) levels, increased heart rate and arterial pressure, and postoperative myalgia associated with SCh administration. The neuromuscular blocking action of SCh was not affected. Pretreatment with d-Tc did not abolish increases in serum K+ and CPK levels, was associated with a higher incidence of postoperative myalgia, and decreased the onset and magnitude of SCh-induced muscle paralysis. Our data demonstrate that diazepam, a predominant centrally acting muscle relaxant, is more effective than d-Tc in preventing the adverse effects of SCh, a peripherally acting muscle relaxant.

Kinetics of high-dose intravenous morphine in cardiac surgery patients.

Ten patients received 1.0 mg/kg of morphine sulfate by constant-rate intravenous infusion at 5 mg/min over 9 to 27 min. Multiple arterial blood samples were drawn during the first 30 to 151 min after termination of the infusion, prior to institution of cardiopulmonary bypass. Postinfusion plasma concentrations were fitted by computer to biexponential functions consistent with a 2-compartment open pharmacokinetic model. Mean (+/- SE) pharmacokinetic parameters were: volume of central compartment, 0.09 +/- 0.03 L/kg; total apparent volume of distribution, 1.02 +/- 0.09 L/kg; distribution T 1/2, 0.90 +/- 0.09 min; apparent elimination T 1/2, 137 +/- 14 min; total clearance, 378 +/- 63 ml/min. Thus distribution of morphine is very rapid, but the apparent volume of distribution is only slightly larger than body weight, suggesting limited tissue uptake. Since apparent elimination T 1/2s are similar to those reported after smaller doses, evidence of saturable or capacity-linked elimination is lacking. Total clearances, representing mainly hepatic clearance, averaged about 25% of hepatic blood flow, suggesting clinically important first-pass metabolism of oral morphine.

Propranolol prevents hemodynamic and humoral events after abrupt withdrawal of nitroprusside.

Hemodynamic and humoral events after intraoperative discontinuation of nitroprusside were studied in subjects without and with pretreatment with intravenous propranolol, 0.1 mg X kg-1. Nitroprusside-induced hypotension was associated with increases in heart rate, cardiac output, plasma renin activity (PRA), and catecholamine levels; these changes were prevented by propranolol. In subjects pretreated with propranolol, dose requirements of nitroprusside for hypotension of comparable degree and duration decreased 40%. On discontinuation of nitroprusside, mean systemic pressure rose to 100.2 mm Hg--a level higher than prehypotension and awake values--because of increased systemic vascular resistance. Hemodynamic events were associated with persistent elevations of PRA and catecholamine levels. These rebound changes were maximal 15 min after nitroprusside withdrawal and returned to control levels 30 to 60 min later. Pretreatment with propranolol completely prevented rebound hemodynamic events after nitroprusside. Persistent elevations of PRA and catecholamine levels after nitroprusside action subsided were responsible for the effects of withdrawal.

Preservation of normal gas exchange with hemodilution in patients with pulmonary hypertension.

The relationship between the plasma colloid osmotic pressure/pulmonary capillary wedge pressure difference (PCOP-PCWP) and the development of gas exchange abnormalities was examined prior to, during, and after cardiac operations in 13 patients with pulmonary hypertension owing to mitral and/or aortic valvular disease. Alveolar-arterial oxygen tension gradient [P(A-a)DO2] and pulmonary shunt fraction (Qs/Qt) were used as indices of gas exchange impairment owing to accumulated lung water. During the baseline period, PCOP-PCWP was -8.5 +/- 2.6 mm Hg; P(A-a)DO2, 352.5 +/- 30.1 mm Hg; and Qs/Qt, 17.0% +/- 1.5%. There were no significant correlations between PCOP-PCWP and P(A-a)DO2 or Qs/Qt at any time during the study. Thus PCOP-PCWP does not predict susceptibility to lung water accumulation reliably in patients with pulmonary hypertension, and other protective factors may contribute to unimpaired gas exchange, even in the setting of profound hemodilution and low PCOP.

Modification of the maze procedure for atrial flutter and atrial fibrillation. I. Rationale and surgical results.

The original maze procedure that was described for the treatment of patients with atrial fibrillation was followed by an unacceptable incidence of two problems: (1) the frequent inability to generate an appropriate sinus tachycardia in response to maximal exercise and (2) occasional left atrial dysfunction. In an effort to overcome these problems, we modified the original technique (maze I) twice. The results of these modifications culminated in the maze III procedure, which is associated with a higher incidence of postoperative sinus rhythm, improved long-term sinus node function, fewer pacemaker requirements, less arrhythmia recurrence, and improved long-term atrial transport function. In addition, the maze III procedure is technically less demanding than either the maze I or maze II procedure. Therefore, the maze III procedure is now the technique of choice for the management of medically refractory atrial fibrillation.

Comparison of activated coagulation time and whole blood heparin measurements with laboratory plasma anti-Xa heparin concentration in patients having cardiac operations.

Previous reports suggest that activated clotting times do not correlate with heparin concentration during cardiopulmonary bypass. This study was designed to compare whole blood heparin concentration and activated clotting time measurements with laboratory-based plasma heparin concentration. Sixty-two patients having cardiac operations requiring cardiopulmonary bypass were enrolled in this study. The study was conducted in two phases. In phase I of this trial, blood specimens were obtained from 30 patients before heparin administration and after each of three heparin doses (20, 80, and 150 U/kg). In phase II, blood specimens were obtained from 32 patients before heparin administration and 10 minutes after each of the following: heparin administration (250 or 300 U/kg), initiation of cardiopulmonary bypass, achievement of hypothermia, initiation of rewarming, and immediately before discontinuation of bypass. Blood specimens were used to measure activated clotting time (kaolin and celite), whole blood heparin concentration, and anti-factor Xa plasma heparin concentration. In phase I, activated clotting time (celite: r = 0.91; kaolin: r = 0.93) and whole blood heparin concentration (r = 0.98) measurements correlated well with plasma heparin concentration. After initiation of cardiopulmonary bypass (phase II), weak correlations for activated clotting time measurements (celite: r = 0.34; kaolin: r = 0.59) and a strong correlation for whole blood heparin concentration (r = 0.95) were evident when compared with plasma heparin concentration. During bypass, activated clotting time measurements also inversely correlated with temperature (celite: r = -0.21; kaolin: r = -0.19) and hematocrit (celite: r = -0.26; kaolin: r = -0.21). A weak correlation between activated clotting time measurements and plasma heparin concentration is evident during the cardiopulmonary bypass period, probably because of the influence of both reduced hematocrit and temperature on the activated clotting time assay. In contrast, whole blood heparin measurements correlate well with plasma heparin concentration before and during bypass. Further studies are needed to determine whether maintaining heparin levels during cardiopulmonary bypass by monitoring heparin concentration is more effective in preventing consumptive activation of the hemostatic system, reducing bleeding, and minimizing the use of blood products after cardiopulmonary bypass when compared with a protocol based on activated clotting time.

Prospective evaluation and clinical utility of on-site monitoring of coagulation in patients undergoing cardiac operation.

Although laboratory coagulation tests permit a rational approach to both diagnosis and management of coagulation disorders after cardiopulmonary bypass, their clinical utility is limited by delays in obtaining results. This study was designed to evaluate prospectively the impact of on-site coagulation testing on blood product use, operative time, and intraoperative management of microvascular bleeding. Patients who underwent cardiac procedures involving cardiopulmonary bypass and subsequently developed microvascular bleeding were randomly assigned to receive either standard therapy (n = 36) or therapy defined by a treatment algorithm based on results from an on-site coagulation monitoring laboratory (n = 30). No differences were found between treatment groups in hematologic assay data, operative procedures, or duration of cardiopulmonary bypass. Patients treated in accordance with on-site laboratory results (algorithm therapy) received significantly less intraoperative fresh frozen plasma (0.4 +/- 1.1 U versus 2.4 +/- 2.8 U; p = 0.0006) during the treatment interval, had shorter operative times, and had less mediastinal chest tube drainage during the initial perioperative interval (158 +/- 169 ml versus 326 +/- 258 ml; p = 0.003) than did patients in the standard therapy group. Patients who underwent algorithm therapy also received fewer platelet (1.6 +/- 5.9 versus 6.4 +/- 8.2 U; p = 0.02) and red blood cell (1.9 +/- 1.7 U versus 4.1 +/- 4.1 U; p = 0.01) transfusions after the operation. Nine of 36 (25%) standard group patients received initial therapy which differed from that which would have been guided by the on-site algorithm protocol. Our findings indicate that rapid and accurate coagulation test results can guide specific therapy and optimize treatment of microvascular bleeding in patients who undergo cardiac operations.

Swallowing dysfunction after cardiac operations. Associated adverse outcomes and risk factors including intraoperative transesophageal echocardiography.

The frequency, importance to patient outcomes, and independent predictors of postoperative swallowing dysfunction documented by barium cineradiography were examined in 869 patients undergoing cardiac operations over a 12-month period. Swallowing dysfunction was diagnosed in 34 patients (4% incidence) and was associated with documented pulmonary aspiration in 90% of these patients, increased frequency of pneumonia (p < 0.0001), need for tracheostomy (p = 0.0002), length of stay in the intensive care unit (p = 0.0001), and duration of hospitalization after the operation (p = 0.0001). Independent predictors of postoperative swallowing dysfunction determined by multivariate logistic regression included age (p < 0.001), length of tracheal intubation after the operation (p = 0.001), and intraoperative use of transesophageal echocardiography (p = 0.003). Dysfunctional swallowing after cardiac operations, a serious complication significantly related to postoperative respiratory morbidity and extended length of hospitalization, is more common in older patients. An association between intraoperative use of transesophageal echocardiography and swallowing dysfunction was also observed in our patients.

The impact of heparin concentration and activated clotting time monitoring on blood conservation. A prospective, randomized evaluation in patients undergoing cardiac operation.

A whole blood hemostasis system (Hepcon) provides both activated clotting time and accurate whole blood heparin concentration measurements via an automated protamine titration method. This study was designed to prospectively evaluate the impact of heparin and protamine administration using this system on the incidence and treatment of bleeding after cardiopulmonary bypass. Two hundred fifty-four patients requiring cardiopulmonary bypass were enrolled in this prospective study over a 7-month period. Patients treated with antifibrinolytic agents (aprotinin, epsilon-aminocaproic or tranexamic acid) were excluded. Patients were randomly assigned to either a control (n = 127) or intervention (n = 127) group. For control patients, the anticoagulation protocol consisted of an initial fixed dose of 250 U/kg of heparin, and additional 5000 U heparin doses were administered if the activated clotting time was less than 480 seconds. Heparin was neutralized with an initial fixed dose of protamine (0.8 mg protamine per milligram total heparin). For the intervention group, an initial dose of heparin was based on an automated heparin dose-response assay. Additional heparin doses were administered if the heparin concentration was less than the reference concentration or for an activated clotting time less than 480 seconds. The protamine dose was based on the residual heparin concentration. Treatment of excessive bleeding after cardiopulmonary bypass was based on an algorithm using point-of-care testing with whole blood prothrombin time, activated partial thromboplastin time, heparinase activated clotting time, and platelet count. No differences between the two treatment groups were identified in reference to demographic factors, preoperative anticoagulant medications, preoperative coagulation data, number of reoperations, or combined procedures and duration of cardiopulmonary bypass. Indirect evidence for coagulation factor consumption was demonstrated in control patients by more prolonged whole blood prothrombin time and activated partial thromboplastin time values after cardiopulmonary bypass when compared with values obtained in the intervention group. Patients in the intervention cohort received greater doses of heparin (intervention: 612 +/- 147, control: 462 +/- 114 U/kg, p < 0.0001) and had lower protamine to heparin ratios (intervention: 0.70 +/- 0.64, control: 0.94 +/- 0.21, p = 0.0001) compared with control patients. Patients in the intervention cohort received significantly fewer platelet (intervention: 1.7 +/- 3.6 U, control: 3.7 +/- 6.7 U, p = 0.003), plasma (intervention: 0.4 +/- 1.3 U, control: 1.4 +/- 2.5 U, p = 0.0001), and cryoprecipitate units (intervention: 0.0 +/- 0.0 U, control: 0.2 +/- 1.2 U, p = 0.04) during the perioperative interval than control patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Five-year experience with the maze procedure for atrial fibrillation.

Between September 25, 1987, and December 31, 1992, 75 patients (53 men, 22 women; average age, 52 years) underwent the maze procedure for the treatment of atrial fibrillation. Six patients had undergone a previous cardiac operation and 28% underwent concomitant cardiac procedures in addition to the maze procedure. One patient (1.3%) died 10 days after undergoing a combined maze procedure and Morrow procedure for the management of chronic atrial fibrillation and hypertrophic obstructive cardiomyopathy. Postoperative atrial pacemakers were required in 40%: 26% for preoperative sick sinus syndrome and 6% for iatrogenic injury of the sinus node, and 8% had pacemakers in place preoperatively. As of December 31, 1992, 65 patients had been followed up for at least 3 months after operation (range, 3 to 63 months). The maze procedure cured atrial fibrillation, restored atrioventricular synchrony, and preserved atrial transport function in 64 of 65 patients (98%). The procedure has been curative without the need for medications in 58 of 65 patients (89%) and with the need for medications in 6 of 65 (9%), with medications failing in only 1 of the 65 patients (2%). The results support the maze procedure as the treatment of choice in patients with medically refractory symptomatic atrial fibrillation.

From fisherman to fibrillation: an unbroken line of progress.

The modern era of cardiac arrhythmia surgery was initiated by Dr Will C. Sealy in May 1968, when he performed the first successful surgical division of an accessory pathway for the treatment of the Wolff-Parkinson-White syndrome. During the subsequent 25 years, arrhythmia operations evolved through a series of innovative surgical procedures capable of curing essentially all refractory clinical arrhythmias. The lessons learned during the development of these surgical procedures ultimately led to the refinement and eventual success of less invasive catheter techniques that have now replaced most of these surgical techniques. The surgical experience gained during these years also made possible the current surgical procedure that is used to treat the most complex, and the most common, of all cardiac arrhythmias, atrial fibrillation. Few areas of any specialty are as clearly defined as the unbroken line of progress that extends from Dr Sealy's first procedure in 1968 to the successful surgical treatment of atrial fibrillation in 1994.

Response of kaolin ACT to heparin: evaluation with an automated assay and higher heparin doses.

BACKGROUND: Because previous reports suggest that the linear relationship between celite activated clotting time (ACT) values and heparin sodium is disrupted if values exceed 500 to 600 seconds, this study was designed to evaluate the relationship of kaolin activated clotting time (ACT) values to high in vitro heparin concentrations. In addition, the relationship of kaolin ACT to heparin concentration as determined manually was compared with that obtained with an automated heparin dose response assay. METHODS: Blood specimens were obtained prior to and after heparin administration from 41 cardiac surgical patients requiring cardiopulmonary bypass in this institutional human studies committee-approved study. Five ACT instruments were used to evaluate the response of kaolin ACT to manually added heparin at two anticoagulation levels: low range (ACT values of less than 500 seconds) and high range (ACT values of 500 seconds or greater). Specimens were also used to measure kaolin ACT values at three heparin concentrations with an automated heparin dose response assay (HDR) using a Hepcon instrument. RESULTS: A greater response of kaolin ACT to heparin was seen with high-range ACT values than low-range ACT values as illustrated by greater (p = 0.002) mean slope values (low range, 99 +/- 30 s/U/ mL; high range, 128 +/- 50 s/U/ml). Good correlations were obtained between heparin concentration and either low- or high-range ACT values as demonstrated by mean correlation coefficients (low range, 0.992; high range 0.982). The response of low-range kaolin ACT values to heparin was greater than that obtained with the automated heparin dose response assay as illustrated by greater (p = 0.005) mean slope values (low range, 99 +/- 30 s/U/mL; HDR, 82 +/- 21 s/U/mL). Good correlations were observed for the relationship between heparin and ACT values obtained with the HDR assay (r = 0.998). CONCLUSIONS: A variable response of kaolin ACT to heparin among patients was demonstrated in our study, especially when ACT values exceeded 500 seconds. We found that the response of kaolin ACT to higher heparin concentrations was acceptable for clinical monitoring based on good correlations obtained in individual patients. The HDR assay generally overestimates a patient's heparin requirements; most likely, this is due to a lower response of kaolin ACT to heparin concentration that is reflected in this assay. Because and exceptional correlation can be obtained between kaolin ACT values and heparin concentration using the assay, this automated assay can identify heparin-resistant patients who may need further treatment.

The effect of hemodilution with albumin or Ringer's lactate on water balance and blood use in open-heart surgery.

To determine the effect of intraoperative albumin administration on blood use, water balance, and postoperative clinical course, we studied two groups of adult cardiac surgical patients. Group I (30 patients) received 25 gm of albumin during withdrawal of 2 units of blood prior to cardiopulmonary bypass (CPB) and 50 gm of albumin in the oxygenator prime. Group II (32 patients) received no albumin prior to the end of CPB. No difference in clinical course could be identified, nor was there a significant difference in blood use. Group I patients had lower hematocrit values intraoperatively from the time of blood withdrawal until the conclusion of operation. Coronary artery bypass operations were associated with greater positive water balance than were heat valve operations. Forty-three percent of the patients having coronary artery bypass grafting had a positive water balance greater than 5 liters, whereas 50% of those undergoing valve procedures had a balance less than 3 liters. We conclude that the principal effect of withholding albumin under these circumstances is to increase net positive water balance. The greater positive water balance does not appear to be detrimental.

Effect of aprotinin on activated clotting time, whole blood and plasma heparin measurements.

Twenty cardiac surgical patients requiring cardiopulmonary bypass were enrolled in this study designed to evaluate the effect of aprotinin on activated clotting time (kaolin and celite), whole blood, and laboratory-based plasma (anti-Xa) heparin measurements. Whole blood heparin measurements were not different (p = 0.98) between aprotinin-treated (3.2 +/- 2.8 U/mL) and control (3.2 +/- 3.0 U/mL) specimens. Plasma anti-Xa heparin measurements were also not different (p = 0.95) between aprotinin-treated (2.7 +/- 2.5 U/mL) and control (2.8 +/- 2.5 U/mL) specimens. The relationship between whole blood (plasma equivalent) and plasma heparin measurements was similar (p = 0.1) in the presence (slope, 1.04; r2 = 0.89) or absence (slope, 1.11; r2 = 0.89) of aprotinin. In contrast to weak correlations between celite (r = 0.50) or kaolin (r = 0.53) activated clotting time values, whole blood heparin measurements correlated well (r = 0.93) with plasma heparin measurements during cardiopulmonary bypass in the presence of aprotinin. These findings indicate that whole blood heparin measurements are unaffected by aprotinin and correlate well with plasma anti-Xa heparin measurements even in the presence of aprotinin. Therefore, the automated protamine titration assay can be used to monitor accurately heparin concentrations in patients receiving aprotinin.

Pressure gradient across the pulmonary artery anastomosis during lung transplantation.

BACKGROUND: Perioperative monitoring of pulmonary artery (PA) pressures in lung transplant recipients is critical. This report characterizes an intraoperative gradient across the PA anastomosis in a series of patients undergoing bilateral sequential lung transplantation. METHODS: Hemodynamic measurements were obtained in a series of 10 patients before anesthetic induction, during one-lung ventilation/perfusion of the newly transplanted first lung with the PA catheter proximal and distal to the anastomosis and after arrival in the intensive care unit. The following measurements were recorded: central venous pressure, cardiac output, PA occlusion pressure, and systemic and pulmonary arterial pressures (systolic, diastolic, mean). RESULTS: Although a systolic pressure gradient of more than 10 mm Hg across the anastomosis was observed in all patients, there was a significant variation in systolic (13 to 59 mm Hg), diastolic (2 to 10 mm Hg), and mean (5 to 27 mm Hg) PA gradients. Mean proximal systolic PA pressure measurements (56.2 +/- 20.6 mm Hg) were greater when compared to measurements obtained distal to the anastomosis (28.6 +/- 10.1 mm Hg, p = 0.001) and to those obtained in the postoperative period (32.1 +/- 9.7 mm Hg, p = 0.004). CONCLUSIONS: The present study demonstrates that during single-lung ventilation and perfusion, the PA pressure measured proximally may not reflect accurately the pressure distal to the vascular anastomosis.

Antiischemic effects of nicardipine and nitroglycerin after coronary artery bypass grafting.

BACKGROUND: We assessed the efficacy of a continuous infusion of nicardipine and nitroglycerin in reducing the incidence and severity of perioperative myocardial ischemia during elective coronary artery bypass grafting procedures in a prospective, randomized, controlled study. METHODS: Patients received either nicardipine infusion (0.7 to 1.4 microg x kg(-1) x min(-1); n = 30) or nitroglycerin (0.5 to 1 microg x kg(-1) x min(-1); n = 30) or neither medication (n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes (MIE) were considered to have occurred with ST-segment depressions or elevations of at least 1 mm and at least 2 mm (for both depressions or elevations), each at J + 60 ms and lasting at least 1 minute, using a two-channel Holter monitor. RESULTS: Only nicardipine significantly decreased the duration (p = 0.02) of the 1-mm or greater minutes per hour (3.2 +/- 1.2 minutes per hour) and eliminated the number (p = 0.02) of the 2-mm or greater minutes per hour (zero minutes per hour) when compared with control patients (17.2 +/- 5.6 minutes per hour and 0.17 minutes per hour, respectively) during the intraoperative postbypass period. CONCLUSIONS: Our results suggest that nicardipine lessened the severity of myocardial ischemia shortly after coronary revascularization and could be considered as an alternative to standard antiischemic therapy.

Predictors, frequency, and indications for cardiopulmonary bypass during lung transplantation in adults.

The records for 162 lung transplantations performed in 158 patients were reviewed with regard to the predictors for, frequency of, and indications for using cardiopulmonary bypass during the procedure. There were a total of 8 en bloc double-lung transplantations, 83 single-lung transplantations, and 71 bilateral single-lung transplantations. Bypass was used electively for all double en bloc and three of the bilateral sequential lung transplantation procedures and for 26 unilateral lung replacement procedures in patients with pulmonary hypertension. Of the remaining patients, 1 single-lung transplant recipient required bypass for correction of a surgical mishap and 18 bilateral single-lung recipients required bypass during replacement of the second lung. No preoperative predictors for the need of bypass could be identified. Among the bilateral sequential lung recipients, the use of bypass did not seem to adversely affect outcome, as expressed in terms of the time until extubation, the time spent in the intensive care unit, and the time required to reach a room air oxygen tension greater than 60 mm Hg.

Hypothermic ischemic arrest versus hypothermic potassium cardioplegia in human beings.

To determine if the addition of potassium enhances the myocardial protective effect of intracoronary perfusion hypothermia during aortic cross-clamping, 50 patients undergoing aortocoronary bypass grafting were studied in a randomized, prospective, double-blind fashion. Twenty-six patients received a cold crystalloid solution infused with a handheld syringe into the root of the cross-clamped aorta every 20 minutes, and 24 patients received the same solution but with 25 mEq/L of potassium chloride added, infused in a similar manner. Both groups were analyzed by mortality, rate of perioperative myocardial infarction (electrocardiographic changes, MB-CPK enzyme release, and preoperative and postoperative gated cardiac blood pool scans), intraoperative hemodynamic changes, intraoperative lactate determinations, postoperative arrhythmias, and requirement for pressor or intraaortic balloon pump support. One patient in the potassium cardioplegia group died (massive pulmonary embolism), and none in the hypothermic perfusion group died. Possible perioperative myocardial infarction was diagnosed by more than one marker in 4 of 26 patients in the hypothermic perfusion group and 5 of 24 patients in the potassium group (p = 0.61). There were no differences between the two groups in terms of hemodynamic changes, lactate production, postoperative arrhythmias, or the need for postoperative hemodynamic support. This study in human beings could not demonstrate a specific protective effect of potassium, beyond that afforded by myocardial perfusion hypothermia and wash-out. The data suggest that myocardial hypothermia, achieved through cold intracoronary arterial perfusion, may be the most important beneficial component of so-called cardioplegia for attaining effective intraoperative myocardial preservation in human beings.

Prevalence of left ventricular diastolic filling abnormalities in adult cardiac surgical patients: an intraoperative echocardiographic study.

The incidence of left ventricular (LV) diastolic abnormalities in adult cardiac surgical patients has not previously been adequately investigated. The present study was performed to characterize LV diastolic filling patterns by performing transesophageal Doppler echocardiographic (TEE) studies in patients undergoing cardiac surgical procedures and thus indirectly assess diastolic function in these patients. Doppler TEE studies were performed and transmitral flow (TMF) and pulmonary venous flow (PVF) velocities were recorded in 104 patients intraoperatively. Peak early (E) and late (A) TMF velocities and systolic (S) and diastolic (D) forward PVF velocities were assessed and deceleration time (DT) was measured in all patients. For analysis, the study patients were classified into three groups according to the ratio of the TMF E to A velocity curves: group I with E/A ratio less than 1.0, group II with E/A ratio of 1.0 to less than 2.0, and group III with E/A ratio of 2.0 or greater. A filling pattern of abnormal LV relaxation was found in 73 patients (E/A < 1.0), a normal or pseudonormal pattern was present in 27 patients (1.0 < or = E/A < or = 2.0), and restrictive filling in 4 patients (E/A > 2.0). Patients with impaired relaxation had a greater incidence of recent myocardial infarction and congestive heart failure (CHF) than those with normal or pseudonormal filling patterns. Within group II, patients with CHF had higher TMF E deceleration rates and lower PVF S/D ratios compared with those without CHF (P < .05). Doppler echocardiographic examination of TMF and PVF velocities suggests that abnormalities in diastolic function are prevalent in adult cardiac surgical patients.

Effects of nicardipine and nitroglycerin on perioperative myocardial ischemia in patients undergoing coronary artery bypass surgery.

Perioperative myocardial ischemic episodes are predictive of adverse cardiac outcomes after coronary artery bypass surgery. We compared the efficacy of continuous infusions of nicardipine (group NIC) and nitroglycerin (group NTG) in reducing the frequency and severity of myocardial ischemic episodes. Patients received either a nicardipine infusion, 0.7 to 1.4 microg/kg/min (n = 30), nitroglycerin infusion, 0.5 to 1 microg/kg/min (n = 30), or neither medication (group C; n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes were considered as ST segment depressions or elevations of 1 mm or greater from baseline, each at J + 60 milliseconds and lasting 1 minute or greater, using a two-channel Holter monitor. Only nicardipine significantly decreased the duration (3.2 +/- 1.2 min/h) and the area under the ST time curve (AUC; 5.7 +/- 15.7 AUC/h) of 1-mm or greater myocardial ischemic episodes compared with group C (17.2 +/- 5.6 min/h and 30.1 +/- 49 AUC/h, respectively) during the intraoperative postbypass period. A trend toward lower frequency, duration, and area under the ST time curve of myocardial ischemic episodes was observed in group NIC compared with group NTG. Cardiac indices and mixed venous oxygen saturations were significantly greater, whereas systemic pressures were less in group NIC compared with group NTG for the same period. These results suggest that nicardipine, but not nitroglycerin, decreased the duration and area under the ST time curve of myocardial ischemic episodes shortly after coronary revascularization. Larger studies are required to verify the efficacy of nicardipine in reducing the severity of myocardial ischemia during cardiac surgery.