Changes in systolic and diastolic function during multivessel off-pump coronary bypass grafting.

OBJECTIVE: To measure the changes in systolic and diastolic left ventricular function that occur during off-pump coronary artery bypass grafting (OPCAB) as a consequence of positioning the heart and interrupting coronary flow. METHODS: 2-D Transoesophageal echocardiography was used to derive systolic wall motion indices and pulsed Doppler parameters of diastolic function including the E/A ratio, PVS/PVD ratio, and deceleration time. A continuous cardiac output thermodilution pulmonary artery catheter was used to provide hemodynamic measures of left ventricular function. Data was obtained prior to, during and following coronary grafting. RESULTS: Thirty-four consecutive anastomoses were evaluated, including eight circumflex (LCX), 17 left anterior descending artery (LAD) and nine right coronary artery (RCA) anastamoses. Significant changes in diastolic and systolic cardiac function were identified in those patients who underwent LCX grafting. Specifically during LCX grafting, both wall motion score index (2.4+/-1.4 vs 1.5+/-0.63 and 1.9+/-0.91) and the E/A ratio were significantly increased (3.5+/-1.4 vs 1.1+/-0.33 and 1.2+/-0.44) when compared to RCA and LAD grafting, respectively. The PVS/PVD ratio was significantly decreased during left circumflex grafting (0.7+/-0.45 vs 1.1+/-0.19 and 1.0+/-0.58) when compared to RCA and LAD grafting, respectively. All functional parameters returned to baseline by the end of surgery. CONCLUSIONS: Multivessel OPCAB can be achieved with mild impairment of left ventricular function that returns to baseline by the end of the procedure. Impairment of diastolic function is most marked during circumflex grafting as demonstrated by a restrictive filling pattern. Measures of diastolic function may be helpful in developing better strategies for exposure of the circumflex graft site.

Transesophageal echocardiography in quantification of emboli during femoral nailing: reamed versus unreamed techniques.

We quantified the embolic load to the lungs created with two different techniques of femoral nailing. Eleven patients with 12 traumatic femur fractures were randomized to reamed (7 fractures) and unreamed (5 fractures) groups. Intramedullary nailing was with the AO/ASIF* universal reamed or unreamed nail. Transesophageal echocardiography (TEE) was used to evaluate the quantity and quality of emboli generated by nailing. Data were analyzed using software that digitized the TEE images and quantified the area of embolic particles in each frame. The duration of each level of embolic phenomena (zero, moderate, severe) was used to determine total embolic load with various steps (fracture manipulation, proximal portal opening, reaming, and nail passage). Manual grading of emboli correlated highly with software quantification. Our data confirm the presence and similarity of emboli generation with both methods of intramedullary nailing. Unreamed nails do not protect the patient from pulmonary embolization of marrow contents.

Finger position for chest compressions in cardiac arrest in infants.

OBJECTIVE: To determine whether the recommended method of locating finger position for chest compression in infant cardiac arrest can cause pressure on the abdomen or xiphisternum. DESIGN: The length from the inter-nipple line to the xiphisternum was calculated in 30 infants. These lengths were compared with the finger position achieved by 30 adults, using the recommended method, on templates of infant chests. RESULTS: The mean infant lower sternal length was 2.3 cm (95% CI 1.6). The mean distance covered by the adults fingers was 4.4 cm (95% CI 0.9). CONCLUSION: If any infant in this study had chest compressions performed by any of the adults, using the recommended method, pressure would be exerted on the xiphisternum or abdomen. We suggest changing the method of locating finger position, to one using sternal anatomy.

Direct aortic cannulation for port-access mitral or coronary artery bypass grafting.

A technique is described for direct aortic arterial cannulation during Port-Access mitral valve or coronary artery bypass grafting. Femoral arterial cannulation is avoided, and endoaortic balloon occlusion is used for cardioplegic arrest. To date, excellent results have been obtained in 45 patients.

Comparison of direct aortic and femoral cannulation for port-access cardiac operations.

BACKGROUND: Differences in outcome after direct aortic cannulation (AORT) in the chest versus standard femoral arterial cannulation (FEM) have not been defined for minimally invasive cardiac operations utilizing the port-access approach. METHODS: A retrospective study was performed of 165 patients undergoing port-access cardiac mitral valve operation (n = 126) or coronary artery bypass grafting (n = 39). In 113 patients, FEM was used, while in 52 patients, AORT was accomplished through a port in the first intercostal space. RESULTS: AORT eliminated endoaortic balloon clamp migration (0/36 [0%] vs. 17/95 [18%]), and groin wound or femoral arterial complications (0/52 [0%] vs. 11/113 [10%]) without changing procedure times (363+/-55 vs. 355+/-70 minutes). Complications attributable to AORT were injury to the right internal mammary artery and aortic cannulation site bleeding in 1 patient each. CONCLUSIONS: Direct aortic cannulation is technically easy, allows use of an endoaortic clamp, and avoids aorto-iliac arterial disease, the groin incision, and possible femoral arterial injury associated with femoral arterial cannulation. Direct arterial cannulation should expand the pool of patients eligible for port-access operation, and may become the standard for port-access procedures.

Mitral valve operation via Port Access versus median sternotomy.

OBJECTIVE: The advantages and disadvantages of minimally invasive Port Access mitral valve operation have not been defined relative to standard median sternotomy. A study was therefore designed to delineate differences in outcome from mitral operation via Port Access versus sternotomy in comparable patients. METHODS: The records of 41 consecutive patients undergoing isolated mitral valve replacement (n = 14) or repair (n = 27) were examined. All operations were performed using cardioplegic arrest through either median sternotomy (n = 20) or a small right anterolateral thoracotomy using an endoaortic clamp and catheter system (Heartport, Redwood City, CA) to arrest and decompress the heart (Port Access, n = 21). RESULTS: Both groups were well matched for age, mitral pathology, ejection fraction, and comorbidity. except that Port Access patients were less likely to be female. Three patients had undergone previous cardiac operations. Surgical procedure time was longer for Port Access patients (384+/-80 vs. 263+/-41 min, P < 0.05). Port Access provided significantly smaller incision length (8+/-2 vs. 26+/-2 cm, P < 0.01) and similar or shorter hospital stay (6+/-4 vs. 7+/-3 days). Port Access provided excellent visualization of the mitral valve and subvalvular apparatus, generally better than sternotomy, to allow complex mitral valve repairs. The greatest advantage of Port Access mitral operation was that Port Access patients returned to normal activity more rapidly (4+/-2 vs. 9+/-1 weeks, P = 0.01) than did patients undergoing standard median sternotomy. CONCLUSIONS: By avoiding a sternotomy, Port Access mitral valve operation provided a smaller incision and a dramatically more rapid return to normal activity than did median sternotomy. Port Access cardioplegic arrest with the Heartport system allowed visualization of the mitral valve superior to median sternotomy and has become the standard approach at this institution.

Cardiopulmonary bypass time does not affect cerebral blood flow.

BACKGROUND: A time-dependent decline in cerebral blood flow (CBF) has been reported in cardiac surgical patients despite stable pump flows and arterial carbon dioxide tension. Other studies have failed to support these hypothermic cardiopulmonary bypass (CPB) results, showing preservation of CBF during CPB. The purpose of the study was to define the influence of mildly hypothermic CPB duration on CBF. METHODS: Cerebral blood flow was measured using xenon-133 washout and alpha-stat blood gas management during nonpulsatile CPB. Cerebral blood flow measurements were made after the initiation of CPB and near the end of bypass during pump flows of 2.4 L.min-1.m-2. RESULTS: Fifty-two coronary artery bypass patients were studied. The average time between CBF measurements was 54 +/- 20 minutes (mean +/- standard deviation), with a range of 10 to 100 minutes. Temperature and arterial carbon dioxide tension were controlled: after the initiation of CPB, temperature was 35.5 degrees +/- 0.4 degree C and carbon dioxide tension was 37 +/- 2.8 mm Hg; whereas near the end of bypass temperature was 35.6 degrees +/- 0.5 degree C and carbon dioxide tension was 36 +/- 2.3 mm Hg. We found no correlation between CBF and time on CPB (p = 0.47; r = 0.101), in contrast to other studies suggesting that CPB duration may intrinsically affect CBF. CONCLUSIONS: Our experimental results include the following: (1) during mildly hypothermic bypass, CBF does not decrease in relation to time and (2) cerebral flow-metabolism coupling is intact at 35 degrees C.

Improvement in inducible ischemia during dobutamine stress echocardiography after transmyocardial laser revascularization in patients with refractory angina pectoris.

OBJECTIVES: The purpose of this ongoing study is to determine whether transmyocardial laser revascularization (TMLR) can lessen inducible ischemia and improve contractile reserve in patients with refractory angina pectoris. BACKGROUND: TMLR is an emerging surgical technique for the treatment of myocardial ischemia and angina pectoris not amenable to conventional percutaneous or surgical revascularization. Objective data documentating a reduction in ischemia during noninvasive stress testing after TMLR are rare. METHODS: Fifteen patients with severe coronary artery disease unsuitable for treatment with standard revascularization techniques were studied with dobutamine stress echocardiography (DSE) before TMLR. Of the 12 patients who underwent TMLR, DSE was repeated at 3 months postoperatively in 11 patients and at 6 months in 9 patients. Stress echocardiograms were analyzed for inducible ischemia, with calculation of the wall motion score index (WMSI). Heart rate and dobutamine dose achieved at peak stress were also assessed as indexes of stress tolerance. RESULTS: Compared with that before TMLR, wall motion at rest for all myocardial segments did not change significantly after TMLR, although there was a mild improvement in the WMSI of the lased myocardial regions ([mean +/- SD] 1.64 +/- 0.34 after vs. 1.78 +/- 0.34 before TMLR, p < 0.05). Overall WMSI at peak stress improved markedly after TMLR (1.70 +/- 0.30 after vs. 2.06 +/- 0.31 before TMLR, p < 0.002), with the improvement in WMSI limited to the lased segments only (1.47 +/- 0.31 after vs. 2.15 +/- 0.34 before TMLR, p < 0.0004). The improvement in WMSI with stress resulted primarily from a decrease in the percentage of ischemic segments (47% before vs. 23% after TMLR, p < 0.0008), with no change in the percentage of infarcted segments (23% before vs. 26% after TMLR). Heart rate (83 +/- 5 beats/min before vs. 102 +/- 21 beats/min after TMLR, p = 0.01) and dobutamine infusion rate (26 +/- 9 micrograms/kg body weight per min before vs. 34 +/- 9 micrograms/kg per min after TMLR) achieved at peak stress also increased postoperatively, consistent with improved stress tolerance. The reduction in ischemic wall motion abnormalities and improved stress tolerance persisted at 6 months, without evidence of further improvement or deterioration of function over time. CONCLUSIONS: TMLR performed in patients with refractory angina pectoris reduces ischemic wall motion abnormalities and improves stress-induced tolerance during dobutamine echocardiography. These beneficial effects persist up to 6 months postoperatively.

Effect of perfusion pressure on cerebral blood flow during normothermic cardiopulmonary bypass.

BACKGROUND: We have recently shown that during hypothermic cardiopulmonary bypass (CPB), cerebral autoregulation has a positive slope such that for every 10 mm Hg change in pressure, a 0.86 mL.100 g-1.min-1 change in cerebral blood flow (CBF) is predicted. The purpose of this study was to define the influence of mean arterial blood pressure (MAP) on CBF during normothermic CPB. METHODS AND RESULTS: CBF was measured by use of 133Xe washout and alpha-stat blood gas management during nonpulsatile CPB. CBF measurements were made at a pump flow of 2.4 L.min-1.m-2 at stable normothermia and approximately 15 minutes later after the MAP was increased or decreased > or = 20%. A third data set was recorded after the pressure was returned to the initial value. Forty-five patients were entered into the study. Temperature was held constant. We found a significant effect (P = .016) of change in MAP on change in CBF during normothermic CPB. For a 10 mm Hg increase in MAP, an increase in CBF of 1.78 mL.100 g-1.min-1 is predicted. Along with change in CBF, significant increases in both cerebral metabolic rate and cerebral oxygen delivery were observed. CONCLUSIONS: This information, along with our previous data shows that autoregulation during CPB has a positive slope that is greater with normothermia than hypothermia. Although it is unlikely that these small changes in flow are an important primary effect in the development of hypoperfusion, increased metabolic rate with increased CBF may indicate pressure-dependent collateral flow potentially in regions embolized during CPB.

Cerebral physiologic effects of burst suppression doses of propofol during nonpulsatile cardiopulmonary bypass. CNS Subgroup of McSPI.

Central nervous system (CNS) complications are common after cardiac surgery. Death due to cardiac causes has decreased, but the number of deaths due to CNS injury has increased. As a first stage in the evaluation of its cerebral protection potential, we evaluated the cerebral physiologic effects of burst suppression doses of propofol during nonpulsatile cardiopulmonary bypass. Thirty patients without history of cerebral vascular disease were randomized to two study groups: control group (n = 15) who received sufentanil and vecuronium, or propofol group (n = 15) who received the control anesthetic and propofol infused to maintain electroencephalogram (EEG) burst suppression. Catheters were placed in the radial artery and right jugular bulb for sampling of systemic arterial and jugular bulb venous blood. 133Xe clearance was used to determine cerebral blood flow (CBF) at the start of normothermic bypass, during stable hypothermia, and when rewarmed to 35-37 degrees C nasopharyngeal temperature. Pharmacologic burst suppression with propofol produced a statistically significant reduction in CBF, cerebral oxygen delivery (DO2), and cerebral metabolic rate (CMRO2) at each measurement interval (P < 0..05 vs control). Cerebral arterial venous oxygen difference (C(a-v)O2), and jugular bulb venous oxygen saturation (SJvO2) were not statistically different between groups, indicating maintenance of cerebral metabolic autoregulation (coupling). The reduction in CBF and CMRO2, prominent during the normothermic phases of cardiopulmonary bypass (CPB), indicates a potential for propofol to reduce cerebral exposure to the embolic load during CPB.

Revascularization of the internal mammary artery after coronary artery bypass grafting.

Symptomatic anterior myocardial ischemia as a result of stenosis at the origin of the left internal mammary artery developed in a patient who underwent prior coronary artery bypass grafting using the left internal mammary artery as a conduit. Successful revascularization of the left anterior descending coronary artery was achieved using a reversed saphenous vein bypass graft from the left common carotid artery to the proximal internal mammary artery. This approach provided myocardial revascularization and avoided reoperative median sternotomy.