Left ventricular assist device (LVAD) enables survival during 7 h of sustained ventricular fibrillation

We describe the case of a patient implanted with a DeBakey left ventricular assist device (LVAD) as bridge to transplant who survived 7 h of ventricular fibrillation. He was successfully converted into a stable sinus rhyth

Composite graft replacement of the aortic root in acute dissection

Objective: In acute type A dissection the indication for composite graft replacement of the aortic root and the optimal implantation technique are a matter of debate. In this study early and late results of root replacement in acute dissection are determined and compared with supracoronary graft replacement. Two implantation techniques (open vs. inclusion) are evaluated. Methods: Between 1985 and 1995, 207 consecutive patients (mean age 58±12 years, 78% men) were operated for acute type A dissection of the aorta. Root replacement in 50 patients (inclusion technique in 34/50 patients with Cabrol shunt in 15/34 patients, open technique in 16/50 patients) was compared with more conservative procedures in 157 patients: supracoronary graft replacement in 143 patients (with aortic valve replacement in 23 patients) and local repair without graft interposition in 14 patients. Preoperative risk factors, like hemodynamic instability, renal failure, neurologic disorder and coronary artery disease did not differ in the two treatment groups. Results: Early results, survival and reoperation-free survival after 5 years were insignificantly better after root replacement; mortality 10/50 (20%) vs. 38/157 (24%) P=n.s.; hemorrhage 10/50 (20%) vs. 39/157 (25%) P=n.s.; stroke 5/50 (10%) vs. 27/157 (17%) P=n.s.; survival 70±7% vs. 63±4%, reoperation free survival 92±6% vs. 78±5% P=0.0815). For the open technique, early mortality was 18.8 vs. 20.6%, P=n.s. and reoperation free survival at 5 years was 80.7 vs. 65.2%, P=n.s. Perioperative complications did not differ in the two technical groups and a single pseudoaneurysm occurred in the Bentall group. Conclusion: In acute dissection composite graft replacement of the aortic root can be carried out with good early and late results not inferior to more conservative procedures. The open technique is the implantation method of choice and the modified Bentall technique is indicated in situations with increased risk of bleedin

Does retrograde cerebral perfusion via superior vena cava cannulation protect the brain?

Objective: The retrograde cerebral perfusion via cannulation of the superior vena cava is a widespread method for optimising protection of the brain during hypothermic circulatory arrest. Methods: In 14 cadavers (8 females, 6 males) of the local department of pathology, an examination was performed to check the competence of the valves of the internal jugular veins. After a complete preparation of the superior vena cava, the innominate vein and both internal jugular veins, ligating all side branches, a retrograde perfusion on 7 cadavers was installed, documenting flow and pressure of each internal jugular vein (IJV) in vitro. Afterwards, the veins were opened and their valves inspected. Results: In all 14 cadavers, anatomically and functionally competent valves on the right proximal IJV were found. Only 1/14 cadaver had no valve in the left proximal IJV. Additional rudimentary and incompetent valves could be identified in 1/14 cadaver on the distal right IJV, and in 2/14 cadavers on the left IJV. Retrograde flow measurement of 7/14 cadavers revealed 0ml/min in 4/7 cadavers, 6ml/min in 1/7, 340ml/min in 1/7 and 2500ml/min in 1/7 cadaver. Conclusions: As a rule, anatomically and functionally competent valves in the proximal IJV are present. In human beings, they obstruct the direct retrograde inlet to the intracranial venous system, which suggests an unbalanced and unreliable perfusion of the brain. Therefore, retrograde cerebral perfusion by cannulating the superior vena cava may help flushing out embolism and supporting ‘the cold jacket' of the brain. However, its effect of retrograde backflow cannot be a sign of adequate cerebral perfusio

Endothelial cell injury in cardiac surgery: salicylate may be protective by reducing expression of endothelial adhesion molecules

Objective: Cardiac surgery with cardiopulmonary bypass induces ischemia to the heart, hypoxemia to various tissues and release of endotoxins. The endothelial cell may suffer from hypoxia and trigger cascades of adverse reactions by activation of neutrophils through adhesion molecules. The authors measured expression of intercellular adhesion molecule-1 (ICAM-1), during hypoxia and normoxia and hypothesized that salicylate, which inhibits the nuclear factor-κB (NFκB), an hypoxia-dependent transmission factor, could reduce this expression. Methods: Human umbilical vein endothelial cells were cultured and exposed to normoxia and hypoxia in the presence of lipopolysaccharide (LPS). The endothelial cells were thereafter treated with salicylate or indomethacin under the same conditions. The surface expression of ICAM-1 was measured by whole cell enzyme-linked immunosorbent assay (ELISA) and the NFκB expression by Western blotting. Results: In the presence of LPS and under hypoxic conditions, the endothelial cells produced a 300±41% increased expression of ICAM-1 compared with normoxia. The addition of salicylate (0.02-20 mM) completely inhibited the enhanced expression of ICAM-1, the addition of indomethacin at equivalent concentrations did not reduce ICAM-1 expression under either condition. Conclusion: ICAM-1 expression is greatly enhanced by the hypoxic endothelial cell in the presence of circulating endotoxin. Pre-treatment with salicylate completely abolishes the enhanced expression. The study suggests that salicylate administered before cardiopulmonary bypass might protect the heart against ischemic/reperfusion injuries and reduce the load of the overall inflammatory reactio

Trajectory of coronary motion and its significance in robotic motion cancellation

Objectives: To characterize remaining coronary artery motion of beating pig hearts after stabilization with an ‘Octopus' using an optical remote analysis technique. Methods: Three pigs (40, 60 and 65 kg) underwent full sternotomy after receiving general anesthesia. An 8-bit high speed black and white video camera (50 frames/s) coupled with a laser sensor (60 μm resolution) were used to capture heart wall motion in all three dimensions. Dopamine infusion was used to deliberately modulate cardiac contractility. Synchronized ECG, blood pressure, airway pressure and video data of the region around the first branching point of the left anterior descending (LAD) coronary artery after Octopus stabilization were captured for stretches of 8 s each. Several sequences of the same region were captured over a period of several minutes. Computerized off-line analysis allowed us to perform minute characterization of the heart wall motion. Results: The movement of the points of interest on the LAD ranged from 0.22 to 0.81 mm in the lateral plane (x/y-axis) and 0.5-2.6 mm out of the plane (z-axis). Fast excursions (>50 μm/s in the lateral plane) occurred corresponding to the QRS complex and the T wave; while slow excursion phases (<50 μm/s in the lateral plane) were observed during the P wave and the ST segment. The trajectories of the points of interest during consecutive cardiac cycles as well as during cardiac cycles minutes apart remained comparable (the differences were negligible), provided the hemodynamics remained stable. Inotrope-induced changes in cardiac contractility influenced not only the maximum excursion, but also the shape of the trajectory. Normal positive pressure ventilation displacing the heart in the thoracic cage was evident by the displacement of the reference point of the trajectory. Conclusions: The movement of the coronary artery after stabilization appears to be still significant. Minute characterization of the trajectory of motion could provide the substrate for achieving motion cancellation for existing robotic systems. Velocity plots could also help improve gated cardiac imagin

Reduced incidence of atrial fibrillation after cardiac surgery by continuous wireless monitoring of oxygen saturation on the normal ward and resultant oxygen therapy for hypoxia

Objective: Monitoring of cardiac surgical patients after transfer from the intensive care unit to the normal ward is incomplete. Undetected hypoxia, however, is known to be a risk factor for occurrence of atrial fibrillation. We have utilized Auricall® for continuous wireless monitoring of oxygen saturation and heart rate until discharge. The object of the study was to analyze if oxygen therapy as a result of Auricall® alerts of hypoxia can decrease the incidence of postoperative atrial fibrillation. Methods: Auricall® is a wireless portable pulse oximeter. An alert is generated depending on preset threshold values (heart rate, oxygen saturation). Over a period of 6 months, 119 patients were monitored with the Auricall® following coronary artery bypass graft and/or valve surgery. Oxygen therapy was started subsequent to an oxygen saturation below 90%. These patients were compared with a cohort of 238 patients from the time period before availability of Auricall®. The patient characteristics were comparable in both groups. In a retrospective study, the incidence of atrial fibrillation was measured in both groups. Results: The postoperative AF was observed in 22/119 patients (18%) in group I and in 66/238 patients (28%) in group II. This difference between the two groups approached significance (p=0.056). In the subgroup of patients with coronary artery bypass graft with our without simultaneous valve surgery (n=312), Auricall® monitoring resulted in a significantly reduced incidence of atrial fibrillation (14% vs 26%, p=0.016). Conclusions: Continuous monitoring of oxygen saturation on the normal ward and subsequent oxygen therapy for hypoxia can reduce the incidence of atrial fibrillation in a subgroup of patients after cardiac surgery. Prospective randomized trials are warranted to confirm these dat

Geometric models of the aortic and pulmonary roots: suggestions for the Ross procedure

Objective: To discuss geometric factors, which may influence long-term results relating to homograft competence following the Ross procedure, we describe the 3D morphology of the pulmonary and aortic roots. Materials: Measurements were made on 25 human aortic and pulmonary roots. Inter-commissural distances and the heights of the sinuses were measured. For geometrical reconstruction the three commissures and their vertical projections at the root base were used as reference points. Results: In the pulmonary root, the three inter-commissural distances were of similar dimensions (17.9±1.6mm, 17.5±1.4mm and 18.6±1.5mm). In the aortic root, the right inter-commissural distance was greatest (18.8±1.9mm), followed by the non-coronary (17.4±2.0mm) and left coronary sinus commissures (15.2±1.9mm). The mean height of the left pulmonary sinus was greatest (20±1.7mm) followed by the anterior (17.5±1.4mm) and right pulmonary sinus (18±1.66mm). In the aortic root, the height of the right coronary sinus was the greatest (19.4±1.9mm) followed by the heights of the non-coronary (17.7±1.8mm) and left coronary sinus (17.4±1.4mm). Measured differences between parameters determine the tilt angle and direction of the root vector. The tilt angle in the pulmonary root averaged 16.26°, respectively; for the aortic roots, it was 5.47°. Conclusions: Herein we suggest that the left pulmonary sinus is best implanted in the position of the right coronary sinus, the anterior pulmonary in the position of the non-coronary sinus and the right pulmonary sinus in the position of the left coronary sinus. In this way, the direction of the pulmonary root vector will be parallel to that of the aortic root vecto

Erythropoietin protects from reperfusion-induced myocardial injury by enhancing coronary endothelial nitric oxide production

Objective: Cardioprotective properties of recombinant human Erythropoietin (rhEpo) have been shown in in vivo regional or ex vivo global models of ischemia-reperfusion (I/R) injury. The aim of this study was to characterize the cardioprotective potential of rhEPO in an in vivo experimental model of global I/R approximating the clinical cardiac surgical setting and to gain insights into the myocardial binding sites of rhEpo and the mechanism involved in its cardioprotective effect. Methods: Hearts of donor Lewis rats were arrested with cold crystalloid cardioplegia and after 45 min of cold global ischemia grafted heterotopically into the abdomen of recipient Lewis rats. Recipients were randomly assigned to control non-treated or Epo-treated group receiving 5000 U/kg of rhEpo intravenously 20 min prior to reperfusion. At 5 time points 5-1440 min after reperfusion, the recipients (n = 6-8 at each point) were sacrificed, blood and native and grafted hearts harvested for subsequent analysis. Results: Treatment with rhEpo resulted in a significant reduction in myocardial I/R injury (plasma troponin T) in correlation with preservation of the myocardial redox state (reduced glutathione). The extent of apoptosis (activity of caspase 3 and caspase 9, TUNEL test) in our model was very modest and not significantly affected by rhEpo. Immunostaining of the heart tissue with anti-Epo antibodies showed an exclusive binding of rhEpo to the coronary endothelium with no binding of rhEpo to cardiomyocytes. Administration of rhEpo resulted in a significant increase in nitric oxide (NO) production assessed by plasma nitrite levels. Immunostaining of heart tissue with anti-phospho-eNOS antibodies showed that after binding to the coronary endothelium, rhEpo increased the phosphorylation and thus activation of endothelial nitric oxide synthase (eNOS) in coronary vessels. There was no activation of eNOS in cardiomyocytes. Conclusions: Intravenous administration of rhEpo protects the heart against cold global I/R. Apoptosis does not seem to play a major role in the process of tissue injury in this model. After binding to the coronary endothelium, rhEpo enhances NO production by phosphorylation and thus activation of eNOS in coronary vessels. Our results suggest that cardioprotective properties of rhEpo are at least partially mediated by NO released by the coronary endotheliu

Normalization of high pulmonary vascular resistance with LVAD support in heart transplantation candidates

Objective: Pulmonary hypertension (PH) and elevated pulmonary vascular resistance (PVR) lead to poor outcome after heart transplantation due to postoperative failure of the non-conditioned right ventricle. The role of continuous flow left ventricular assist device (LVAD) support in the reduction of elevated PVR was evaluated in a series of clinical implants. Methods: Among 17 patients with terminal heart failure receiving a MicroMed DeBakey LVAD as bridge to transplant, there were six patients with pulmonary hypertension (mean systolic PAP 47mmHg) and high PVR (398dynes/cm5), previously not considered suitable for heart transplantation, who underwent serial right heart catheters during their LVAD support period. Results: In these patients mean systolic pulmonary pressure dropped to 29mmHg and PVR decreased to a mean 167dynes/cm5 under LVAD support. Clinical improvement was significant in all patients. Four patients were successfully transplanted without major postoperative difficulties (mean duration 130 days support) and all are doing well to date. Post-transplant-PVR remained in the normal range in all transplanted patients. Conclusions: Elevated PVR and severe PH were both previously considered as contraindication for heart transplantation. A period of LVAD pumping leads to a progressive decrease of PVR and normalization of pulmonary pressures, making these patients amenable for heart transplantation. LVAD as bridge to heart transplantation is safe and highly beneficial for terminal heart failure patients with severe P

Conservative treatment of the aortic root in acute type a dissection

Objective: In acute type A dissection long-term results of conservative aortic root surgery were compared with the outcome of primary valve and/or root replacement. Methods: Between 1985 and 1995, 199 patients (mean age 59 years, 154 men) were operated on. The aortic root was involved in the dissection process and valve incompetence of varying degree was present without exception. Replacement of a proximal aortic segment was standard procedure in all patients. The aortic valve was preserved in 126 patients: commissural suture resuspension (12 patients), root reconstruction with GRF-glue (gelatine-resorcin-formaldehyde/glutaraldehyde-glue) (114 patients). Valve replacement was performed in 73 patients (50 composite grafts, 23 valve prostheses with separate supracoronary grafts). Preoperative risk factors (valve replacement vs. preservation): coronary artery disease (11 vs. 8%, NS), tamponade (18 vs. 17%, NS), unstable hemodynamics (22 vs. 15%, NS), renal failure (4 vs. 6%, NS), neurologic disorder (19 vs. 32%, NS). Results: The overall early mortality was 23.6% (47/199 patients) and increased after commissural suture resuspension compared with GRF-glue reconstruction (P=NS). Parameters of the early postoperative period did not differ between conservative treatment and root/valve replacement: low cardiac output, 34 versus 38% (P=NS); myocardial infarction, 10 versus 11% (P=NS); hemorrhage, 25 versus 23% (P=NS); duration of intensive care (P=NS). Survival was 61% after 8 years without difference between the two principal treatment groups (P=NS) and between the two conservative subgroups (P=NS). At 2 years, GRF-glue reconstruction had an increased freedom from reoperation on the aortic root (92 vs. 70%, P=0.0253) and event free survival (77 vs. 41%, P=0.0224) compared with suture resuspension. Commissural suture resuspension was an independent, significant predictor for reoperation (P=0.0221, relative risk=4.7130). Conclusion: Surgery for acute type A dissection still carries a considerable early risk. Preservation of the aortic root is safe in the absence of Marfan or annuloaortic ectasia, but a certain incidence of reoperations on the aortic valve and the aortic root has to be accepted. Root reconstruction using GRF-glue is the method of choice and is superior to suture resuspension, with a significantly better reoperation-free and event-free surviva