Stephen N. Harris

Intraoperative Determination of Cardiac Output Using Multiplane Transesophageal Echocardiography A Comparison to Thermodilution

Background Limitations in the imaging views that can be obtained with transesophageal echocardiography (TEE) have hindered development of a widely adopted Doppler method for cardiac output (CO) monitoring. The authors evaluated a CO technique that combines steerable continuous‐wave Doppler with the imaging capabilities of two‐dimensional multiplane TEE. Methods From the transverse plane transgastric, short‐axis view of the left ventricle, the imaging array was rotated to view the left ventricular outflow tract (LVOT) and ascending aorta. Steerable continuous‐wave Doppler was subsequently used to measure aortic blood flow velocities. Aortic valve area was determined using a triangular orifice model. Matched thermodilution and Doppler CO measurements were obtained serially during surgery. Results The left ventricular outflow tract was imaged in 32 of 33 patients (97%). Data analysis reveal a mean difference between techniques of ‐ 0.01 l/min, and a standard deviation of the differences of 0.56 l/min. Multiple regression showed a correlation of r = 0.98 between intrasubject changes in CO. Multiplane TEE correctly tracked the direction of 37 of 38 serial changes in thermodilution CO but with a modest 14% underestimation of the magnitude of these changes. Conclusions These results indicate that multiplane TEE can provide an alternative method for the intraoperative measurement of CO. The ability of the rotatable imaging array to align with the left ventricular outflow tract and the need for only minimal adjustments in probe position advance the utility of intraoperative TEE.

Alterations of cardiovascular performance during laparoscopic colectomy: a combined hemodynamic and echocardiographic analysis.

We investigated cardiovascular performance in 12 patients (mean age 66 +/-12 yr) with significant coexisting cardiopulmonary disease (hypertension, coronary artery disease, chronic obstructive pulmonary disease) during laparoscopic colectomy under general anesthesia. Hemodynamic monitors included arterial and pulmonary artery catheters in combination with transesophageal echocardiography. Hemodynamic and echocardiographic data were obtained at five epochs: baseline (after induction of anesthesia), insufflation (after pneumoperitoneum, supine position), Trendelenburg 5 (5 min after placement into Trendelenburgs position), Trendelenburg 20 (at 20 min in Trendelenburgs position), and end (after release of the pneumoperitoneum, supine position). Hemodynamic responses to peritoneal insufflation resulted in significant increases in systemic vascular resistance (SVR) as well as endsystolic area (ESA) and significant decreases in cardiac index (CI) and ejection fraction area (EFa) compared with baseline. Trendelenburgs positioning augmented ventricular preload and performance, resulting in significant increases in pulmonary capillary wedge pressure, CI, end-diastolic area, and EFa compared with insufflation. At the final epoch, end, a hyperdynamic state occurred as evidenced by a significantly decreased ESA and SVR while heart rate, CI, and EF (a) increased significantly compared to baseline and insufflation. In an elderly population with significant coexisting cardiopulmonary disease, intraoperative maneuvers required for laparoscopic colectomy resulted in previously undescribed alterations of cardiovascular performance, which persisted after release of the pneumoperitoneum. (Anesth Analg 1996;83:482-7)

Intraoperative hemodynamic changes are not good indicators of myocardial ischemia.

Intraoperative myocardial ischemia is associated with an increased risk of a perioperative myocardial infarction (PMI) in patients undergoing coronary artery bypass graft surgery. If reversible physiologic variables could be identified that are indicators of myocardial ischemia, treatment might be instituted early to prevent cardiac morbidity. In patients undergoing elective coronary artery bypass graft surgery, we evaluated the relationship between several premorbid patient characteristics, selected hemodynamic variables, intraoperative myocardial ischemia, and a PMI. In addition we evaluated these selected hemodynamic variables as intraoperative indicators of myocardial ischemia. The following variables were evaluated: heart rate, > 80 beats/min; systolic arterial blood pressure, > 160 mm Hg; systolic arterial blood pressure, < 80 mm Hg; mean arterial blood pressure, < 60 mm Hg; pulmonary artery diastolic pressure, > 18 mm Hg; a 5 mm Hg increase in pulmonary artery diastolic pressure; rate pressure product, > 12,000 beats/min.mm Hg; and a pressure rate quotient, < 1.0 mm Hg/beats/min. The premorbid patient characteristics selected were previous myocardial infarction, recent myocardial infarction (within 1 wk of surgery), type and number of coronary lesions, beta-blocker therapy, and calcium blocker therapy. One hundred consecutive (n = 100) patients for elective coronary artery bypass graft surgery were studied prospectively before the initiation of cardiopulmonary bypass (CPB). Patients were monitored with a Hewlett Packard computer ST segment analyzer using leads II and V5. Ischemia was defined as the new onset of ST segment deviation of > or = 1 mm from the baseline electrocardiogram (ECG) (preinduction) for at least 2 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Transesophageal two-dimensional echocardiographic analysis of right ventricular systolic performance indices during coronary artery bypass grafting

Sixteen patients (aged 59 +/- 14 years) undergoing coronary artery bypass surgery were evaluated to delineate the intraoperative course of transesophageal echocardiographic right ventricular (RV) systolic performance indices. Pre-induction data included thermodilution RV ejection fraction (RVEFTD), 0.43 +/- 0.13, RV end-diastolic volume index (EDVI), 110 +/- 33 mL/m2, cardiac index (CI), 3.4 +/- 1.0 L/min/m2, RV end-diastolic pressure (EDP), 7.1 +/- 4.2 mmHg, and mean pulmonary artery pressure (PAP), 21 +/- 6 mmHg. Eleven patients had significant right coronary artery (RCA) disease (> 70% occlusion). Five patients arrived with an ongoing nitroglycerin infusion (1 to 3 micrograms/kg/min), which was maintained intraoperatively. Echocardiographic measurements included longitudinal-axis (LA) and short-axis (SA) planimetered area excursion fractions (2DLA and 2DSA, respectively) and LA maximal major and minor axis shortening fractions (max majorLA and max minorLA, respectively). Hemodynamic measurements included RVEFTD, EDVI, CI, EDP, and PAP. Measurements were determined following induction/endotracheal intubation, following sternotomy/pericardiotomy, and after cardiopulmonary bypass (CPB) with the chest open. All patients were maintained on vasodilator therapy post-CPB (nitroglycerin, 1 to 3 micrograms/kg/min [N = 16] and nitroprusside, 0.5 to 4.5 microgram/kg/min [N = 4]) post-CPB. Two patients received inotropic support (epinephrine, 0.2 to 0.3 microgram/kg/min). CPB was associated with significant decreases in max major axisLA and 2DLA (P < 0.05) as compared to measurements determined prior to CPB. Maximum major axisLA values pre-CPB were 0.35 +/- 0.06 and 0.33 +/- 0.08 versus post-CPB values of 0.24 +/- 0.08.(ABSTRACT TRUNCATED AT 250 WORDS)

Quality assurance for intraoperative transesophageal echocardiography monitoring: A report of 846 procedures

We evaluated our experience with 846 consecutive transesophageal echocardiography (TEE) intraoperative monitoring procedures performed between November 1989 and July 1991. TEE frequency was 36 +/- 11 per month (range 16-55) and represented 69.8% of cardiac valve surgery cases, 40.2% of coronary artery bypass graft cases, and 2.2% of total operative caseload. Major patient complications consisted of transient vocal cord paresis and ingestion of glutaraldehyde-disinfectant solution. Minor complications consisted of a chipped tooth (one case) and pharyngeal abrasions (three cases). The Quality Assurance (Q/A) Program evaluated both record keeping and quality of imaging, as judged by cardiologist echocardiographer reviewers. The percentage of completion for each Q/A indicator was as follows: medical record documentation, 88%; database form annotation, 94%; and provision of videotape recording, 91%. TEE database forms were analyzed further in terms of the percentage of fields completed. Completion scores were 73%. The following scoring system was utilized for videotape evaluation by the cardiologists: 1 = excellent; 2 = good; 3 = poor. The median grade for both two-dimensional echocardiography and color flow Doppler (CFD) examinations was 2. Poor quality images (grade 3) were present in 15.2% of two-dimensional echocardiography and 20.3% of color flow Doppler examinations, and disproportionately associated with 4/26 attendings. Supplemental audit of the cardiology reviewers performance demonstrated 569/846 videotapes showed no objective evidence of review. The cardiology reviewer forms of the remaining 277 videotapes were evaluated in terms of the percentage of fields completed. The completion score was 56%. These data suggest the need for formal Q/A for intraoperative TEE, both for anesthesiologists and reviewing cardiologists.

Nitroprusside Inhibition of Platelet Function Is Transient and Reversible by Catecholamine Priming

BACKGROUND The time course and reversibility of sodium nitroprussides in vivo inhibition of platelet function are unclear. METHODS Platelet aggregation and P-selectin expression as measures of platelet dense and alpha-granule release, respectively, were examined before and after administration of sodium nitroprusside (18 mg) to human volunteers and in in vitro studies. Hypotension occurring with sodium nitroprusside administration was treated with intravenous crystalloid and/or phenylephrine. RESULTS Compared with preinfusion studies, platelet aggregation to epinephrine was significantly inhibited immediately and 4 min after discontinuation of the sodium nitroprusside infusion but returned to baseline at 8 and 12 min after discontinuing sodium nitroprusside. However, both dense and alpha-granule release to adenosine diphosphate after in vivo sodium nitroprusside were never significantly inhibited even at the time when sodium nitroprusside infusion was maximal. In contrast to our in vivo findings, in vitro incubation of platelet-rich plasma with sodium nitroprusside resulted in significant inhibition of dense and alpha-granule release to adenosine diphosphate. These in vitro inhibitory effects of sodium nitroprusside were reversed by pretreatment with epinephrine but not phenylephrine. CONCLUSIONS In normal volunteers, sodium nitroprusside inhibits platelet aggregation to epinephrine but not adenosine diphosphate; inhibition was reversed within 8-12 min after discontinuing sodium nitroprusside. Sodium nitroprusside in vitro inhibition of platelet function to adenosine diphosphate was reversed by epinephrine pretreatment. Because of the rapid reversibility of its antiplatelet effect, sodium nitroprusside may be clinically useful even when there is the potential for impaired coagulation.

The pressure rate quotient is not an indicator of myocardial ischemia in humans : an echocardiographic evaluation

Background:The pressure rate quotient (PRQ; mean arterial pressure/heart rate [MAP/HR]) less than one (PRQ < 1) has been proposed as a simple, clinically available hemodynamic index of myocardial ischemia. Recent investigations using electrocardiography (ECG) detection of myocardial ischemia have not found this index reliable. We prospectively compared PRQ < 1 to detection of myocardial Ischemia via transesophageal echocardiography (TEE) and ECG in patients undergoing elective coronary artery bypass graft. Methods:Forty-six of 50 patients admitted into the study had acceptable data acquisition. Calibrated ECG leads II and V5 were recorded with a computerized ST-segment analyzer. Hemodynamic data were stored at 2-min intervals. After tracheal intubation, a 5.0-MHz TEE probe was inserted. Electro-cardiography-detected ischemia was defined as new onset ST-segment deviation (≥ mm) lasting for >1 min. Trans-esophageal echocardiography determination of ischemia was worsening of wall motion ≥ grade and lasting >1 min. PRQ < 1 was compared to ECG and/or TEE as a predictor or indicator of myocardial ischemia. Results:Electrocardiography ischemia occurred during 230 intervals in 10 patients, and in only 41 of 230 (18%) was PRQ < 1. Transesophageal echocardiography-defined ischemia occurred during 592 intervals in 9 patients, and in 119 of 592 (20%) PRQ < 1. Compared to ECG and TEE, PRQ < 1 had a low sensitivity (21%) and poor positive predictive value (25%). Conclusions:Pressure rate quotient < 1 is an unreliable indicator and predictor of myocardial ischemia when evaluated by ECG, TEE, and the combination of these modalities In patients undergoing coronary artery bypass graft surgery.

Thermodilution right ventricular ejection fraction measurement reproducibility : a study in patients undergoing coronary artery bypass graft surgery

ObjectiveTo assess the effects of heart rate, right ventricular systolic performance (ejection fraction), chamber dimensions, and flow rate (cardiac index) on the reproducibility of algorithm-derived triplicate thermodilution right ventricular ejection fraction measurements. DesignProspective study; combined hemodynamic and echocardiographic clinical evaluation. SettingOperating room in a university hospital. PatientsTwenty-one coronary artery bypass graft patients. Measurements and Main ResultsThe right atrial delivery site was positioned by analysis of transduced pressure waveform and echocardiographic imaging of tracer agitated saline cavitations. Measurement reproducibility was quantified by determining the variation (standard deviation) within 101 triplicate thermodilution measurement sets. There was no significant relationship between measurement reproducibility and estimates of right atrial area (21.6 ± 6.9 cm2), diameter (5.1 ± 0.8 cm) and supero-inferior length (5.1 ± 0.9 cm) and right ventricular maximal minor axis diastolic diameter (4.21 ± 1.05 cm). Reproducibility was also unrelated to right ventricular end-diastolic volume index (97.9 ± 32.7 mL/m2) and cardiac index (2.9 ± 0.9 L/min/m2). Measurement reproducibility was directly related to mean right ventricular ejection fraction (0.39 ± 0.14) and inversely related to heart rate (80.8 ± 18.6 beats/min) (p < .01 and < .001, respectively). ConclusionsThermodilution-derived right ventricular ejection fraction measurement reproducibility was unrelated to estimates of right atrial and ventricular dimensions and cardiac index. Measurement reproducibility was a direct function of right ventricular systolic performance and an indirect function of heart rate. Measurement should be interpreted with these constraints in mind.

A clinical computer database entry form for an intraoperative anesthesiology-based transesophageal echocardiography monitoring service

Transesophageal echocardiography (TEE) has been increasingly applied to supplement and, in instances, to supplant conventional intraoperative cardiac monitoring. Our body of experience (>1600 intraoperative TEE procedures), combined with insights gleaned from an intramural quality assurance study, and clinical implications of certain recent advances in the field, led us to develop the following TEE computer database entry form. The form, completed intraoperatively, consists of a patient and surgical procedure demographics section, followed by fields based on the TEE examination. The scans encompass transverse plane basal short axis, long axis, and transgastric views of the heart and great vessels. The two-dimensional echocardiographic, saline-contrast, color flow and pulsed Doppler data represent both right and left ventricular performance, valvular function and specific lesions. This database entry form is intended to serve as a guide for performance of a nominally complete intraoperative study and facilitate maintenance of a TEE archive consistent with current advances.

Multiplane Transesophageal Echocardiographic Acquisition of Ascending Aortic Flow Velocities: A Comparison with Established Techniques☆☆☆★

Acquisition of ascending aortic flow velocities with monoplane transesophageal echocardiography (TEE) have been problematic because of limitations of available imaging planes and alignment of the Doppler beam with aortic flow. The rotatable imaging array of multiplane TEE (Multi TEE) may provide improved alignment with ascending aortic blood flow. The purpose of this study was to establish the validity of maximal aortic flow velocities (VMax) and velocity time integrals (VTI) obtained by a Multi TEE continuous wave Doppler technique by comparison with those obtained by established echocardiographic techniques, suprasternal Doppler (SSD), and monoplane TEE (Mono TEE). Forty-five patients scheduled for elective surgery were prospectively studied. Multi TEE-obtained VMax and VTI were significantly greater (P <.05), 120 +/- 28.9 cm/s and 25.8 +/- 7 cm, than those obtained by the SSD method, 100.2 +/- 28.6 cm/s and 19.8 +/- 6.8 cm, respectively. Bias analysis revealed that Multi TEE better assessed VMax (mean difference -19.7, SD of the difference of 28 cm/s) and VTI (mean difference -5.9, SD of the difference of 6.4 cm) than the SSD method. Multi TEE exhibited values for VMax 10% or greater than those obtained by SSD in 18 (48. 6%) of 37 patients, and Multi TEE was 10% or greater than SSD in 23 (67%) of 37 patients for VTI determination. Values obtained by Multi TEE and Mono TEE showed close agreement. Multi TEE provides a favorable alignment for continuous wave Doppler interrogation of aortic flow and compared favorably to established techniques. This technique expands the utility of TEE to evaluate aortic valvular function and cardiac performance.