Venous graft perforation leading to cardiac tamponade.

We describe a cardiac tamponade after venous graft perforation due to stent inflation. The complications and therapeutic options are discussed.

Risk of aortic dissection after aortic valve replacement.

Little information is available regarding the incidence of aortic dissection after previous aortic valve replacement (AVR), and factors associated with its development. Therefore, a meta-analysis of the literature was performed, and a patient population was studied retrospectively. Data from published studies showed that 87% of 31 patients were men (mean age 60 years), and 68% were known to have systemic hypertension. A dilated ascending aorta was observed at the time of AVR in 88% of patients. AVR was performed because of pure aortic regurgitation in 55% of patients, and combined aortic stenosis and regurgitation in 23%. More than 50% of patients did not survive dissection. The present series consisted of 7 patients. Four patients were known to the department before dissection occurred, and the other 3 were referred by other hospitals. Eighteen of 330 patients with previous AVR whose data were stored in an echocardiographic data base had an ascending aortic diameter > 50 mm. Of these 18 patients, aortic dissection occurred in 4. Three of the remaining 14 patients underwent elective ascending aortic replacement. Characteristics including sex, age, severity of dilatation, presence of progression in diameter, left ventricular function and time interval after AVR were not helpful in determining a cumulative risk for developing dissection. Because dissection occurred in 4 of 18 patients (22%) with an ascending aorta diameter > 50 mm, it is suggested to consider replacement of the ascending aorta during AVR when a value of 50 mm is exceeded.

Systemic inflammation present in patients undergoing CABG without extracorporeal circulation.

STUDY OBJECTIVES: This study was conducted to evaluate to what extent the cardiopulmonary bypass (CPB) procedure in patients undergoing coronary artery bypass grafting (CABG) contributes to the systemic inflammatory response. Therefore, we measured bactericidal permeability increasing protein (BPI) as an indicator of neutrophil activation, interleukin 6 as inducer of the acute phase response, and lipopolysaccharide binding protein and C-reactive protein as parameters of the acute phase response in patients undergoing CABG either with or without the use of CPB. DESIGN: Prospective study. SETTING: Cardiopulmonary surgery department in a university hospital. PATIENTS: Sixteen patients undergoing elective CABG were included. Eight patients underwent surgery with CPB, and eight patients underwent surgery without CPB (non-CPB). INTERVENTIONS: In the CPB group, blood samples were taken upon induction of anesthesia, at the start of aortic cross-clamping, at aortic unclamping, and 0.5, 4, 8, and 18 h thereafter. In the non-CPB group, blood samples were taken upon induction of anesthesia, and 0.5, 4, 8, and 18 h after completion of the bypass graft anastomoses. MEASUREMENTS AND RESULTS: BPI release from neutrophil granules markedly increased during surgery in CPB patients but not in non-CPB patients. The increase in acute phase reactants, however, was the same in both patient groups. CONCLUSIONS: These data indicate that the acute phase response in CABG patients, which has historically been ascribed to the CPB procedure, is predominantly caused by the surgical procedure per se. Early neutrophil activation, however, is seen only when extracorporeal circulation is used.

Epicardial left ventricular lead placement for cardiac resynchronization therapy: optimal pace site selection with pressure-volume loops.

OBJECTIVES: Patients in heart failure with left bundle branch block benefit from cardiac resynchronization therapy. Usually the left ventricular pacing lead is placed by coronary sinus catheterization; however, this procedure is not always successful, and patients may be referred for surgical epicardial lead placement. The objective of this study was to develop a method to guide epicardial lead placement in cardiac resynchronization therapy. METHODS: Eleven patients in heart failure who were eligible for cardiac resynchronization therapy were referred for surgery because of failed coronary sinus left ventricular lead implantation. Minithoracotomy or thoracoscopy was performed, and a temporary epicardial electrode was used for biventricular pacing at various sites on the left ventricle. Pressure-volume loops with the conductance catheter were used to select the best site for each individual patient. RESULTS: Relative to the baseline situation, biventricular pacing with an optimal left ventricular lead position significantly increased stroke volume (+39%, P =.01), maximal left ventricular pressure derivative (+20%, P =.02), ejection fraction (+30%, P =.007), and stroke work (+66%, P =.006) and reduced end-systolic volume (-6%, P =.04). In contrast, biventricular pacing at a suboptimal site did not significantly change left ventricular function and even worsened it in some cases. CONCLUSIONS: To optimize cardiac resynchronization therapy with epicardial leads, mapping to determine the best pace site is a prerequisite. Pressure-volume loops offer real-time guidance for targeting epicardial lead placement during minimal invasive surgery.

Myocardial substrate uptake and oxidation during and after routine cardiac surgery.

OBJECTIVE: This study was designed to clarify whether myocardial substrate uptake and oxidation change after a period of hypothermic cardioplegic arrest during coronary artery bypass grafting procedures. METHODS: In 30 patients arterial and coronary sinus blood was sampled and coronary sinus flow measurements were performed before and after sternotomy and 10 minutes, 20 minutes, 50 minutes, and 6 hours after release of the aortic crossclamp. Measurement of free fatty acids, lactate, glucose, oxygen content, and carbon dioxide content in arterial and coronary sinus blood allowed calculations of myocardial substrate use, respiratory quotients, and myocardial oxidation rates of carbohydrates and fat. RESULTS: Uptake of free fatty acids and lactate was significant throughout the study and did not change in association with release of the crossclamp. Free fatty acid and lactate uptake measured 6 +/- 4 micromol/min and 23 +/- 26 micromol/min, respectively, before crossclamping compared with 8 +/- 7 micromol/min and 19 +/- 21 micromol/min, respectively, after release of the clamp. Glucose uptake was significant only during the first hour after crossclamp release and increased from 7 +/- 50 to 28 +/- 34 micromol/L after crossclamp release. Myocardial oxygen consumption did not change significantly (0.5 +/- 0.2 mmol/L compared with 0.35 +/- 0.2 mmol/L) after release of the crossclamp. Myocardial oxygen extraction ratio decreased from 58% +/- 8% to 41% +/- 13% after crossclamp release. Respiratory quotient increased after crossclamp release (0.85 +/- 0. 2 compared with 1.00 +/- 0.2), which implies that carbohydrate oxidation increased at the expense of free fatty acid oxidation. CONCLUSION: We conclude that hypothermic cardioplegic arrest during coronary artery bypass graft operations is associated with a transiently increased uptake and oxidation of carbohydrates during the immediate reperfusion phase.

The enabler right ventricular circulatory support system for beating heart coronary artery bypass graft surgery.

BACKGROUND: Beating heart coronary artery bypass graft surgery of the left anterior descending, diagonal, and right coronary artery can be performed safely with the Octopus Stabilization System. However, tilting of the heart, which is necessary to reach the obtuse marginal and distal right coronary arteries, causes hemodynamic instability. This study was performed to investigate the possible role of the Enabler right ventricular circulatory support system in counteracting this instability. METHODS: In 8 sheep, the Enabler cannula was introduced via the jugular vein and positioned with the inlet valve in the right atrium and outlet valve in the pulmonary artery. The Octopus was used to expose the inferior wall and the posterior wall of the left ventricle. The hemodynamic effects of this tilting with and without Enabler right ventricular support were recorded, including Pressure Volume (PV) loops measured by conductance catheters in both ventricles. RESULTS: Tilting caused a reduction in stroke volume (inferior 31%, posterior 17%) and Enabler activation increased stroke volume (inferior 13%, posterior 31%). CONCLUSIONS: Tilting the heart has severe hemodynamic consequences that can be partially counteracted by the use of the Enabler for right ventricle support.

Glutamate metabolism of the heart during coronary artery bypass grafting.

Glutamate infusion has been shown to exert beneficial hemodynamic effects in patients with heart failure after cardiac surgery. To elucidate the underlying mechanism we studied the possibility that glutamate is a Krebs-cycle precursor in the human heart. Therefore [1-13C]glutamate was infused in order to show production of 13CO2 by the heart. In five patients a primed constant infusion of [1-13C]glutamate was started 2|h before the start of sampling from coronary sinus and arterial blood. Plasma concentrations of glutamate and glutamine were determined by high pressure liquid chromatography. Blood concentration of CO2 and enrichment of [1-13C]glutamate, [1-13C]glutamine and [1-13C]glutmaine and 13CO2 were measured by GC-IRMS. The results show that approximately 85% of [1-13C]glutamate taken up by the heart is released released as 13CO2. These results show that synthesis of Krebs-cycle intermediates is a major fate of the glutamate extracted by the human heart.

Right ventricular support for off-pump coronary artery bypass grafting studied with bi-ventricular pressure--volume loops in sheep.

OBJECTIVES: Tilting the heart during off-pump coronary artery bypass grafting (OPCABG) causes a strong decrease in cardiac output. It is hypothesized that this decrease is caused by reduced right ventricular filling and that right ventricular support is thus the best way to restore cardiac output. Simultaneous left and right ventricular pressure-volume loops were used to test this hypothesis. METHODS: In seven sheep, the heart was tilted with the use of an Octopus device. After unsupported tilting, a novel right ventricular support, the Enabler, was activated at a pulsatile flow of 1.6 l/min. Pressure-volume loops of both ventricles were obtained using conductance catheters, and cardiac output was monitored with an aortic flow probe. RESULTS: Tilting reduced cardiac output by 31% (4.4--3.1 l/min, P=0.001) and right ventricular end-diastolic volume by 44% (86--51 ml, P=0.005), while right ventricular end-diastolic pressure did not decrease. Left ventricular systolic pressure was not significantly reduced upon tilting and even increased in two animals. During Enabler right ventricular support, the cardiac output remained 23% lower than pre-tilting values (3.4 vs. 4.4 l/min, P=0.001). CONCLUSIONS: Restricted right ventricular filling is the primary cause of the strong decrease in cardiac output during tilting. The Enabler right ventricular support can currently not restore cardiac output to pre-tilting values, mainly caused by its limited output and a decrease in right ventricular output upon Enabler activation. Constant monitoring of cardiac output is crucial during (unsupported or supported) tilting as blood pressure alone may not reflect the extent of the reduction in cardiac function.

Ruptured aneurysm of the left sinus of Valsalva into the pericardium.

Recently, a 67-year-old female patient came to our attention after a collapse, due to cardiac tamponade caused by a ruptured sinus of Valsalva aneurysm (SVA) and intrapericardial bleeding. Despite surgical intervention the patient died before correction.

Giant intrapericardial aneurysm of the left atrial appendage.

A young patient is reported with an aneurysm of the left atrial appendage having supraventricular arrhythmias and a period of chest pain accompanied by a rise in cardiac enzymes. Compression of the left anterior descending coronary artery by the aneurysm was felt to be responsible for the myocardial injury.

Comparison of arterial wall reaction after passage of the Hydrolyser device versus a thrombectomy balloon in an animal model.

PURPOSE: This study was designed to compare the reaction of the vessel wall after application of the Hydrolyser hydrodynamic thrombectomy device to the reaction after use of a balloon thrombectomy catheter. The influence of the vessel inner diameter on vessel wall reaction was evaluated after passage of the Hydrolyser. MATERIALS AND METHODS: After measurement of the vessel inner diameter with intravascular ultrasound (US), 102 segments of femoral and carotid arteries of goats were treated with one of the following four procedures: passage of the intravascular US catheter alone; passage of the Hydrolyser without or with an activated jet; or passage of an inflated thrombectomy balloon. Histologic evaluation was performed after 3 weeks. RESULTS: Intimal thickening (more than five cell layers of neointima) 3 weeks after treatment occurred more frequently after passage of the balloon than after any of the other procedures (P < .001). For vessels with a diameter of 3-4 mm, 4-5mm, or more than 5 mm, no significant difference in vessel wall reaction was observed following Hydrolyser passage. CONCLUSION: In this model, passage of the Hydrolyser device resulted in less intimal reaction compared with the thrombectomy balloon.

The effect of glutamate infusion on cardiac performance is independent of changes in metabolism in patients undergoing routine coronary artery bypass surgery.

In a double-blind randomized placebo-controlled study, the effects of intravenous glutamate infusion on myocardial haemodynamics and metabolism were studied in 22 patients undergoing routine coronary artery bypass graft (CABG) surgery. Immediately after aortic cross-clamp release, an intravenous infusion of a solution of glutamate (125 mmol x l(-1)) at a rate of 1.5 ml x h(-1) x kg(-1) was given over 1 h to 11 patients (G group). The other 11 patients received a placebo infusion (0.9% NaCl) (P group). Haemodynamic functions and rates of exchange of glucose, non-esterified fatty acids and lactic acid over the heart were measured before sternotomy (T1), 40 min after cross-clamp release (T2) and 4 h after cross-clamp release (T3). At T2, decreases were seen in comparison with T1 in systemic vascular resistance index, and increases were seen in cardiac index and coronary sinus flow. All of these changes were greater in the G group than in the P group (P<0.05). Myocardial glutamate consumption increased 2-fold after glutamate administration. No significant changes were observed in the myocardial utilization of glucose, lactate or non-esterified fatty acids between the P and the G groups at T1, T2 or T3. These data show that an intravenous glutamate infusion after routine CABG surgery significantly improved cardiac haemodynamic performance without direct effects on cardiac substrate metabolism. This suggests that a reduction of the afterload via a peripheral vasodilatory effect is the main mechanism leading to the observed changes in haemodynamics. Earlier claims that patients with post-operative cardiac failure show metabolic benefits from the glutamate infusion do not seem to apply to patients undergoing routine CABG surgery.