Yasu Oka

Application of transesophageal echocardiography to continuous intraoperative monitoring of left ventricular performance

Transesophageal M mode echocardiography was used for continuous monitoring of left ventricular dimensions in 21 patients (11 with valvular and 10 with coronary heart disease) undergoing open heart surgery. Echocardiograms were recorded in six stages of the procedure and simultaneous measurements of cardiac output (with dye dilution) and atrial pressures were made. Measurements of left ventricular diameters with the transesophageal technique correlated excellently with the corresponding measurements obtained with the standard parasternal method. In patients with volume overload, surgical correction was accompanied by a decrease in diastolic dimension, velocity of circumferential fiber shortening, mid wall stress and end-diastolic stiffness, and an increase in cardiac output. Pericardial and chest wall closures generally caused a significant decrease in cardiac output, and correlated with a decrease in diastolic diameter and an increase in the stiffness constant of the left ventricle. Thus, the decrease in cardiac output may have been due to decreased distensibility of the ventricular cavity secondary to mechanical restriction by the pericardium and chest wall. Pericardial opening caused a significant delay in septal motion that was reversed by closing the pericardium. This study confirms the validity of transesophageal echocardiography and its usefulness in monitoring changes in ventricular function during cardiac surgery.

beta-Blockade therapy for supraventricular tachyarrhythmias after coronary surgery: a propranolol withdrawal syndrome?

A high incidence of cardiac arrhythmias and hypertension has been noted after coronary artery bypass surgery in patients previously treated with oral propranolol. Forty-two patients undergoing coronary bypass surgery had propranolol withdrawal 10 hours before surgery and were randomized into a group treated with propranolol immediately postoperatively, and a nontreatment group. Patients treated with prophylactic propranolol had a significantly lower incidence of postoperative supraventricular arrhythmias compared to patints who received no prophylaxis. All the arrhythmias responded rapidly to 1 mg of intravenous propranolol therapy, whether it was used as a primary treatment or as a supplement to prophylactic propranolol. The findings suggest that (1) there is a high incidence of supraventricular arrhythmias and sinus tachycardia after coronary artery bypass which might reflect an abrupt propranolol withdrawal, and (2) that perioperative prophylactic or supplementary propranolol therapy will successfully prevent or treat most of these arrhythmias.

Clinical pharmacology of the new beta-adrenergic blocking drugs. Part 10. Beta-adrenoceptor blockade and coronary artery surgery

Abstract In an attempt to resolve the controversy concerning propranolol therapy in patients undergoing coronary artery revascularization surgery, 54 consecutive patients with stable angina pectoris receiving chronic propranolol therapy entered a randomized trial and were compared with 17 patients on no propranolol therapy (group I). The 54 patients were divided into three treatment groups: in group II (n = 17) propranolol was abruptly withdrawn 48 hours prior to surgery, in group III (n = 18) propranolol was abruptly withdrawn 10 hours prior to surgery, in group IV (n = 19) propranolol was maintained until the day of surgery, half the usual dose was given 2 hours prior to surgery, and intravenous propranolol was administered every four hours postoperatively. Patients in group II and III had significantly higher increases in the rate-pressure product (RPP) during intubation, and in the postoperative periods compared to patients in groups I and IV. Group IV had the lowest increase in RPP during intubation and a significantly lower incidence of postoperative supraventricular arrhythmias. Patients abruptly withdrawn from propranolol, at 10 or 48 hours preoperatively, are more prone to increments in myocardial oxygen demands than those patients not treated with propranolol postoperatively or who were maintained on the drug. Plasma renin activity, although lower in patients treated with propranolol (group IV), did not seem to play a role in the RPP increments seen. The increased sympathetic tone associated with intubation and the postoperative period most likely contribute to the increments in RPP and the increased incidence of arrhythmia. These data show that (1) propranolol may be given safely to patients at the time of coronary artery bypass and may be maintained postoperatively without a decrement in left ventricular performance; (2) there is a “rebound effect” or increased sympathetic activity in patients who have propranolol abruptly withdrawn 10 or 48 hours prior to surgery. This “rebound effect” causes a marked increase in myocardial oxygen demands during intubation and the postoperative periods, with an increased incidence of arrhythmias. (3) Continuous propranolol treatment up until the time of surgery with maintenance of intravenous therapy in the immediate postoperative period provides protection against these complications. (4) The data and implications can reasonably be expected to apply to propranolol-treated patients with angina pectoris undergoing general anesthesia and noncardiac surgical procedures.

New Applications of Two-Dimensional Transesophageal Echocardiography in Cardiac Surgery

This article describes new applications of two-dimensional transesophageal echocardiography (2D-TEE), including (1) detection of pleural fluid (PF) and atelectasis (AT), and (2) evaluation of various cannulation techniques. The left and right pleural spaces were visualized by rotating the probe counterclockwise and clockwise, respectively, from the four-chamber view. PF was depicted as a crescent-shaped echo-free space, enclosed by the lung and posterior chest wall on both sides. AT was often accompanied by PF and was depicted as a less echogenic area in the lung parenchyma. During removal of PF, the echo-free space gradually decreased in size to the point of disappearing completely, while the lung parenchyma expanded and became more echogenic. TEE was advantageous in detecting PF and AT located in the most dorsal parts of the pleural space and lung parenchyma. The aorta acted as an acoustic window on the left side. TEE was found useful in evaluating the cannulae position of the intraaortic balloon pump (IABP) and ventricular assist device (VAD), and femoral cannulae for cardiopulmonary bypass (CPB). During use of the IABP, the chamber and shaft were visualized clearly and both malposition of the catheter tip and malfunction of the balloon were easily detected. For VAD, TEE readily showed the collapse of the ventricular cavity due to excessive drainage of blood from the left ventricle, as well as the favorable result of immediate reduction of flow rate. For femorofemoral extracorporeal bypass, TEE detected improper position of the venous cannula. These new applications of TEE can be performed with minimal manipulation of the probe, enabling early detection of the problems and initiating timely and appropriate therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative assessment of pulmonary vein flow.

This study was undertaken to assess the suitability for intraoperative pulmonary vein flow measurements in 15 patients undergoing coronary artery bypass grafting. Using two‐dimensional color Doppler transesophageal echocardiography, all four pulmonary veins—right upper and lower and left upper and lower pulmonary veins were easily visualized. Pulmonary vein flow was pulsatile. J wave occurred in the ventricular systole with relaxation of the left atrium and K wave in the ventricular diastole with relaxation of the left ventricle. There were differences in suitability for flow measurements among four pulmonary veins: (1) consistent visualization; (2) stable visualization throughout measurement; (3) minimal angle between ultrasonic beam and pulmonary vein course; and (4) minimal shift of sampling volume during measurement. The left pulmonary veins were suitable for flow velocity measurement by transesophageal echocardiography. The left lower pulmonary vein was stable for visualization once it was visualized although the angle was occasionally large. The left upper pulmonary vein was consistently visualized although the angle was occasionally large. On the other hand, the right pulmonary veins were unsuitable for flow measurement. Since sampling volume shifted in the direction of the long axis by the average of 5 to 6 mm during cardiac cycle, it should be positioned inside of the pulmonary vein at about 5 mm from the orifice of the left atrium.

Evaluation of hepatic venous flow using transesophageal echocardiography in coronary artery bypass surgery: An index of right ventricular function

Hepatic venous flows (HVFs) were evaluated to assess right-heart function by transesophageal Doppler echocardiography in 45 patients undergoing coronary artery bypass graft (CABG) surgery. Peak velocity and time velocity integral of A-wave (reverse flow in end diastole), S-wave (forward flow in systole), V-wave (reverse flow in late systole), and D-wave (forward flow in diastole) of biphasic HVF were examined. Peak systolic-diastolic ratio (S/D) of biphasic HVF and reverse flow ratio (% reversal flow/forward flow [RF/FF]) of both biphasic and monophasic HVF also were examined. Tricuspid regurgitation (TR) was assessed by color Doppler image. All data were obtained after performing the following: induction of anesthesia (stage 1); pericardiectomy (stage 2); cardiopulmonary bypass (CPB) (stage 3); and closure of sternum (stage 4). HVFs at stage 1 were obtained in all 45 patients, and the peak S/D in patients with a history of inferior wall myocardial infarction (MI) was significantly less than that in patients without a history of MI (p < 0.05). HVFs of 35 patients were recorded successfully at all stages. In 5 of these 35 patients, HVF patterns became monophasic after CPB, and only one of those patients had severe TR. In the rest of the 30 patients with biphasic patterns throughout the operation, peak A and D velocities increased (p < 0.01), whereas peak S and V velocities decreased (p < 0.01) after CPB compared with those before CPB. Consequently, peak S/D was reduced (p < 0.01), and %RF/FF increased (p < 0.05). These post-CPB changes were associated with increased (p < 0.01) pulmonary artery diastolic and right atrial pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Does transesophageal echocardiography improve postoperative outcome in patients undergoing coronary artery bypass surgery

The incidence and characteristics of ischemic episodes as detected by transesophageal echocardiography (TEE) and their relationship to postoperative myocardial infarction (MI) and adverse clinical outcome were studied in patients undergoing coronary artery bypass grafting (CABG). Seventeen of 50 patients had 21 TEE-defined ischemic episodes: 4 patients (8%) had 4 ischemic episodes in the pre-cardiopulmonary bypass (CPB) period, and 15 patients (30%) had 17 ischemic episodes in the post-CPB period, whereas 19 patients had 20 ECG ischemic episodes: 3 patients (6%) had 3 ischemic episodes in the pre-CPB period and 17 (34%) had 17 ischemic episodes in the post-CPB period. In 14 patients, ischemic episodes were detected by both TEE and ECG. Clinicians were made aware of the TEE data and appropriate treatments were undertaken during ischemic episodes: of the 15 patients with TEE-defined post-CPB ischemia, 4 had an additional saphenous vein graft placed, 8 had an intra-aortic balloon pump (IABP) inserted, 3 were given sublingual nifedipine, and 13 received nitroglycerin. These treatments resulted in improvement in regional wall motion abnormalities (RWMA) by the end of surgery in 11 of the 15 patients (73%), including the 4 with postoperative MI and 2 who died with cardiogenic shock. The authors conclude that: (1) significantly more patients had TEE-defined ischemic episodes in the post-CPB period (30%) than in the pre-CPB period (8%); (2) a poor graft and/or inadequate myocardial protection were strongly suggestive of post-CPB ischemia, which was significantly related to adverse outcome; and (3) TEE was a useful tool enabling detection of problem areas at an early stage and timely and appropriate treatment to support and sustain patients.

CORTISOL AND ANTIDIURETIC HORMONE RESPONSES TO STRESS IN CARDIAC SURGICAL PATIENTS

The hormonal responses to anaesthesia and cardiac surgery were studied in patients undergoing valve or coronary bypass surgery. Marked increases in antidiuretic hormone levels as a result of surgical stress were seen, and were of approximately equal magnitude in both groups. Although both groups also showed marked increases in plasma cortisol levels in response to operations, this response appeared to be relatively blunted in valve surgery patients, especially at the end of operation and in the intensive care unit. This blunted cortisol response may be a manifestation of exhaustion of adrenocortical reserves in valvular surgical patients whose sympathoadrenal system has already been chronically stimulated by a low output state.The important role of the neuroendocrine system in maintaining homeostasis postoperatively has long been recognized; this relative cortisol deficiency may be aetiologically related to poor postoperative recovery in critically ill valvular surgery patients.RéSUMéLes réponses hormonales à l’anesthésie et à la chirurgie ont fait l’objet de la présente étude effectuée chez un groupe de malades soumis à une chirirgie valvulaire ainsi que chez ceux d’un second groupe subissant une chirurgie coronarienne. On a observé une élévation marquée de 1’hormone anti-diurétique secondaire au stress de la chirurgie et cette élévation était semblable chez les patients des deux groupes. Le taux du cortisol s’est également élévé chez les patients des deux groupes en réponse au stress chirurgical, mais cette réponse était atténuée chez les valvulaires, en particulier en fin d’intervention et dans la phase postoperatoire immédiate. Une telle réponse chez les valvulaires peut refiéter l’epuisement des réserves adreno-corticales chez des patients dont le système adreno-sympathique a été stimulé de façon chronique par la présence d’un bas débit cardiaque.Le rôle important du systéme neuro-endocrinien dans le maintien du l’homoéostase post-opératoire est connu depuis longtemps; la déficience relative en cortisol peut contribuer ç une évolution post-opératoire difficile chez des patients en condition critique.

Diagnosis of myocardial ischemia by the pressure-rate quotient and diastolic time interval during coronary artery bypass surgery☆

Diagnosis of intraoperative myocardial ischemia by the rate-pressure product (RPP), pressure-rate quotient (PRQ), and diastolic time interval (DTI) was studied in 13 patients undergoing coronary artery bypass grafting (CABG) with fentanyl, vecuronium/pancuronium, and enflurane anesthesia. Criteria for ischemia were 1 mm of ST segment elevation or depression or T wave inversion on the ECG. RPP was calculated by multiplying the systolic arterial pressure (SAP) times the heart rate (HR); PRQ was determined by dividing the mean arterial pressure (MAP) by the HR; and DTI was defined as the interval from the closure of the aortic valve on M-mode transesophageal echocardiography to the onset of the QRS complex on the ECG. Six of 13 patients experienced episodes of ischemia (a total of 32 episodes out of 134 measurements). RPP of 12,000 was not found to correlate with myocardial ischemia (P greater than 0.05), whereas PRQ of less than 1.0 or DTI of less than 400 ms was associated with myocardial ischemia (P less than 0.005). In this preliminary study, it is concluded that both the PRQ and DTI are indicators of myocardial ischemia; it is also suggested that ischemia may be prevented by maintaining (1) DTI over 400 ms (HR less than 75 beats per minute), and (2) PRQ greater than 1.0 (MAP greater than HR).

The anatomical location of the transesophageal echocardiographic transducer during a short-axis view of the left ventricle.

This study was performed to clarify the location of a transesophageal echocardiographic (TEE) transducer when obtaining the short-axis view of the left ventricle (S-LV). The depth of the probe tip from the incisors when obtaining a S-LV, the relationship to the diaphragm, and the location of the cardia of the stomach using a gastroscope attached to the TEE probe were measured in 24 patients undergoing coronary artery bypass grafting. The location of the transducer relative to the cardia and diaphragm was determined. The study demonstrated that when obtaining a S-LV, the transducer was in the stomach in 72.7%, at the cardia in 13.6%, and in the esophagus in 13.6% of the patients. The predominantly intragastric position of the transducer suggests that gastric diseases should be included as contraindications to TEE. When the probe was advanced about 40 cm from the incisors, some resistance was often encountered by the TEE operator at about the level of the diaphragm. Careful manipulation is mandatory to avoid tissue damage by the probe. Visualization of the S-LV can be disturbed by gas in the stomach. This is a specific problem in anesthetized patients because gas is often pushed into the stomach at the time of induction.