Andreas Espinoza

Agreement between PiCCO pulse-contour analysis, pulmonal artery thermodilution and transthoracic thermodilution during off-pump coronary artery by-pass surgery

Background:  Haemodynamic instability during off‐pump coronary artery bypass surgery (OPCAB) may appear rapidly, and continuous monitoring of the cardiac index (CI) during the procedure is advisable. With the PiCCO monitor, CI can be measured continuously and almost real time with pulse‐contour analysis and intermittently with transthoracic thermodilution. The agreement between pulmonal artery thermodilution CI (Tpa), transthoracic thermodilution CI (Tpc) and pulse‐contour CI (PCCI) during OPCAB surgery has not been evaluated sufficiently.

Detection of myocardial ischaemia by epicardial accelerometers in the pig

BACKGROUND We describe a novel technique for continuous real-time assessment of myocardial ischaemia using a three-axis accelerometer. METHODS In 14 anaesthetized open-chest pigs, two accelerometers were sutured on the left ventricle (LV) surface in the perfusion areas of the left anterior descending (LAD) and circumflex (CX) arteries. Acceleration was measured in the longitudinal, circumferential, and radial directions, and the corresponding epicardial velocities were calculated. Regional LV dysfunction was induced by LAD occlusion for 60 s. Global LV function was altered by nitroprusside, epinephrine, esmolol, and fluid loading. Epicardial velocities were compared with strain by echocardiography during LAD occlusion and with aortic flow and LV dP/dt(max) during interventions on global LV function. RESULTS LAD occlusion induced ischaemia, shown by lengthening in systolic strain in the LV apical anterior region (P<0.01) and concurrent changes in LAD accelerometer circumferential velocities during systole (P<0.01) and during the isovolumic relaxation phase (P<0.01). The changes in accelerometer circumferential velocities during LAD occlusion were greater compared with the changes during the interventions on global function (P<0.01). For the LAD accelerometer circumferential velocities, sensitivity was 94-100% and specificity was 92-94% in detecting ischaemia. CONCLUSIONS Myocardial ischaemia can be detected with epicardial three-axis accelerometers. The accelerometer had the ability to distinguish ischaemia from interventions altering global myocardial function. This novel technique may be used for continuous real-time monitoring of myocardial ischaemia during and after cardiac surgery.

Feasibility of a three-axis epicardial accelerometer in detecting myocardial ischemia in cardiac surgical patients

OBJECTIVE We investigated the feasibility of continuous detection of myocardial ischemia during cardiac surgery with a 3-axis accelerometer. METHODS Ten patients with significant left anterior descending coronary artery stenosis underwent off-pump coronary artery bypass grafting. A 3-axis accelerometer (11 x 14 x 5 mm) was sutured onto the left anterior descending coronary artery-perfused region of left ventricle. Twenty episodes of ischemia were studied, with 3-minute occlusion of left anterior descending coronary artery at start of surgery and 3-minute occlusion of left internal thoracic artery at end of surgery. Longitudinal, circumferential, and radial accelerations were continuously measured, with epicardial velocities calculated from the signals. During occlusion, accelerometer velocities were compared with anterior left ventricular longitudinal, circumferential, and radial strains obtained by echocardiography. Ischemia was defined by change in strain greater than 30%. RESULTS Ischemia was observed echocardiographically during 7 of 10 left anterior descending coronary artery occlusions but not during left internal thoracic artery occlusion. During ischemia, there were no significant electrocardiographic or hemodynamic changes, whereas large and significant changes in accelerometer circumferential peak systolic (P < .01) and isovolumic (P < .01) velocities were observed. During 13 occlusions, no ischemia was demonstrated by strain, nor was any change demonstrated by the accelerometer. A strong correlation was found between circumferential strain and accelerometer circumferential peak systolic velocity during occlusion (r = -0.76, P < .001). CONCLUSIONS The epicardial accelerometer detects myocardial ischemia with great accuracy. This novel technique has potential to improve monitoring of myocardial ischemia during cardiac surgery.

Advantages of strain echocardiography in assessment of myocardial function in severe sepsis: an experimental study.

Objectives:Cardiovascular failure is an important feature of severe sepsis and mortality in sepsis. The aim of our study was to explore myocardial dysfunction in severe sepsis. Design:Prospective experimental study. Setting:Operating room at Intervention Centre, Oslo University Hospital. Subjects:Eight Norwegian Landrace pigs. Interventions:The pigs were anesthetized, a medial sternotomy performed and miniature sensors for wall-thickness measurements attached to the epicardium and invasive pressure monitoring established, and an infusion of Escherichia coli started. Hemodynamic response was monitored and myocardial strain assessed by echocardiography. Measurements and Main Results:Left ventricular myocardial function was significantly reduced assessed by longitudinal myocardial strain (–17.2% ± 2.8% to –12.3% ± 3.2%, p = 0.04), despite a reduced afterload as expressed by the left ventricular end-systolic meridional wall stress (35 ± 13 to 18 ± 8 kdyn/cm2, p = 0.04). Left ventricular ejection fraction remained unaltered (48% ± 7% to 49% ± 5%, p = 0.4) as did cardiac output (6.3 ± 1.3 to 5.9 ± 3 L/min, p = 0.7). The decline in left ventricular function was further supported by significant reductions in the index of regional work by pressure-wall thickness loop area (121 ± 45 to 73 ± 37 mm × mm Hg, p = 0.005). Left ventricular myocardial wall thickness increased in both end diastole (11.5 ± 2.7 to 13.7 ± 2.4 mm, p = 0.03) and end systole (16.1 ± 2.9 to 18.5 ± 1.8 mm, p = 0.03), implying edema of the left ventricular myocardial wall. Right ventricular myocardial function by strain was reduced (–24.2% ± 4.1% to –16.9% ± 5.7%, p = 0.02). High right ventricular pressures caused septal shift as demonstrated by the end-diastolic transseptal pressure gradient (4.1 ± 3.3 to –2.2 ± 5.8 mm Hg, p = 0.01). Conclusions:The present study demonstrates myocardial dysfunction in severe sepsis. Strain echocardiography reveals myocardial dysfunction before significant changes in ejection fraction and cardiac output and could prove to be a useful tool in clinical evaluation of septic patients.

Endoscopic treatment of bronchial carcinoids in comparison to surgical resection: a retrospective study.

Background:Surgery is the gold standard of lung carcinoid treatment. However, bronchoscopic treatment may provide a complete cure in selected patients. The aim of the study was to review the results of laser treatment of bronchial carcinoids and to compare the outcome after laser resection against the outcome after surgical resection. Methods:Seventy-three patients, 29 men and 44 women, median age 53 years (range, 23 to 78 y), with bronchial carcinoids were treated by surgical resection (n=48) or endobronchial ablation (n=25). Bronchoscopic treatment was also performed in 5 of 48 surgical patients as a part of the surgical treatment strategy. Results:Among 25 patients treated endoscopically, 16 were successfully treated with laser, whereas 9 were operated subsequently. One major complication was registered, as an inadvertent ventilation caused a nonfatal fire of the bronchoscope during Nd:YAG laser procedure. Forty-eight patients underwent surgical resection. Most of the patients underwent lobectomy and bilobectomy (30 and 5 patients, respectively). Four of the patients were dead by the end of the study, 1 was treated with laser, and 3 treated with surgical resection. The overall survival was 94.5% in the surgical group and 94.4% in the group treated with endoscopic ablation (P=0.9). None of the 69 survivors had any sign of recurrence on computed tomographic scans and bronchoscopy by the end of the study. Conclusions:This is a retrospective study and no randomization has been performed. However, the results add evidence to the view that transbronchial laser treatment may be offered as a safe, stand-alone procedure in the treatment of typical carcinoid tumor in the central airways.

Detecting myocardial ischaemia using miniature ultrasonic transducers — a feasibility study in a porcine model

BACKGROUND Detection of myocardial ischaemia during and after cardiac surgery remains a challenge. Echocardiography is more sensitive in ischaemia detection than echocardiography (ECG) and haemodynamic monitoring, but demands repeated examinations for monitoring over time. We have developed and validated an ultrasonic system that permits continuous real-time assessment of myocardial ischaemia using miniature epicardial ultrasound transducers. METHODS In an open-chest porcine model (n=8), prototype ultrasound transducers were fixed on the epicardium in the left anterior descending and circumflex coronary artery supply regions, providing continuous measurement of transmural myocardial velocities. Peak systolic velocity and post-systolic velocity were recorded simultaneously with ECG, left ventricular pressure and arterial pressure. Two-dimensional (2D) echocardiographic strain was used as a reference. Global changes were induced by infusing fluid, epinephrine, nitroprusside and esmolol. Regional changes were induced by occluding the left anterior descending coronary artery (LAD). Subsequent LAD stenosis was performed in a subgroup, with flow reduction to 50% of baseline level and further to occlusion. RESULTS Systolic velocity in the LAD region decreased during LAD occlusion (0.9+/-0.1 to 0.1+/-0.1 cm s(-1), P<0.01), whereas post-systolic velocity increased (0.3+/-0.1 to 2.3+/-0.1 cm s(-1), P<0.01). No changes occurred in the circumflex coronary artery (CX) region. Severe ischaemia was confirmed by reduction in 2D echocardiography strain calculations. Changes in myocardial velocities assessed by miniature transducer during ischaemia differed from changes during all global interventions. Significant reduction in systolic velocity occurred at 50% LAD flow (0.9+/-0.1 to 0.5+/-0.1 cm s(-1), P=0.02) with further decrease on following occlusion (0.0+/-0.0 cm s(-1), P<0.01). Post-systolic velocity increased both from baseline to 50% LAD flow, and further to occlusion. CONCLUSION The epicardial transducers provided continuous assessment of regional myocardial function and detected ischaemia with high sensitivity and specificity. Further development of this system may provide a useful tool for myocardial monitoring during and after cardiac surgery.

Automatic real-time detection of myocardial ischemia by epicardial accelerometer

OBJECTIVE Myocardial ischemia may be detected with epicardial accelerometers. We developed and tested automated algorithms for real-time detection of myocardial ischemia by accelerometer measurements in both experimental and clinical settings. METHODS In 10 pigs, an accelerometer was fixed to the epicardium in the area perfused by left anterior descending coronary artery. Acceleration and electrocardiogram were simultaneously recorded, and the QRS complex was automatically detected for exact timing of systole. Peak circumferential velocity and displacement were automatically calculated from epicardial acceleration signal within 150 milliseconds after peak R on electrocardiography. Global myocardial function was reduced by esmolol infusion, and regional function was altered by temporary left anterior descending occlusion. Automated ischemia detection analyses were tested in 7 patients during off-pump coronary artery bypass grafting. Left anterior descending coronary artery was occluded for 3 minutes before grafting. In both models, echocardiographic myocardial circumferential strain was used to confirm ischemia. RESULTS Systolic displacement changed most during left anterior descending occlusion. Negative displacement during ischemia was found in pigs (11.5 +/- 2.3 to -1.2 +/- 2.8 mm, P < .01); regional hypokinesia was found in clinical study (12.8 +/- 8.1 to 3.5 +/- 4.4 mm, P < .01). Ischemia was confirmed by echocardiography in both settings. Esmolol infusion induced smaller changes in automated accelerometer measurements than did left anterior descending occlusion (P < .01). CONCLUSIONS Automatic real-time detection of myocardial ischemia with epicardial accelerometer was feasible. Automated ischemia detection analysis may be used for continuous monitoring of myocardial ischemia during cardiac surgery.

Cardiac monitoring using transducers attached directly to the heart

Cardiac ultrasound systems deliver excellent information about the heart, but are constructed for intermittent imaging and interpretation by a skilled operator. This paper presents a dedicated ultrasound system to monitor cardiac function continuously during and after cardiac surgery. The system uses miniature 10 MHz transducers sutured directly to the heart surface. M-mode images give a visual interpretation of the contraction pattern, while tissue velocity curves give detailed quantitative information. The ultrasound measurements are supported by synchronous ECG and pressure recordings. The system has been tested on pigs, demonstrating M-mode and tissue velocity measurements of good quality. When occluding the LAD coronary artery, the system detected changes in contraction pattern that correspond with known markers of ischemia. The system uses dedicated analog electronics and a PC with digitizers and LabVIEW software, and may also be useful in other experimental ultrasound applications.

Systolic left ventricular function is preserved during therapeutic hypothermia, also during increases in heart rate with impaired diastolic filling

BackgroundSystolic left ventricular function during therapeutic hypothermia is found both to improve and to decline. We hypothesized that this discrepancy would depend on the heart rate and the variables used to assess systolic function.MethodsIn 16 pigs, cardiac performance was assessed by measurements of invasive pressures and thermodilution cardiac output and with 2D strain echocardiography. Left ventricle (LV) volumes, ejection fraction (EF), transmitral flow, and circumferential and longitudinal systolic strain were measured. Miniaturized ultrasonic transducers were attached to the epicardium of the LV to obtain M-mode images, systolic thickening, and diastolic thinning velocities and to determine LV pressure-wall dimension relationships. Preload recruitable stroke work (PRSW) was calculated. Measurements were performed at 38 and 33°C at spontaneous and paced heart rates, successively increased in steps of 20 up to the toleration limit. Effects of temperature and heart rate were compared in a mixed model analysis.ResultsHypothermia reduced heart rate from 87 ± 10 (SD) to 76 ± 11 beats/min without any changes in LV stroke volume, end-diastolic volume, EF, strain values, or PRSW. Systolic wall thickening velocity (S′) and early diastolic wall thinning velocity decreased by approximately 30%, making systolic duration longer through a prolonged and slow contraction and changing the diastolic filling pattern from predominantly early towards late. Pacing reduced diastolic duration much more during hypo- than during normothermia, and combined with slow myocardial relaxation, incomplete relaxation occurred with all pacing rates. Pacing did not affect S′ or PRSW at physiological heart rates, but stroke volume, end-diastolic volume, and strain were reduced as a consequence of reduced diastolic filling and much more accentuated during hypothermia. At the ultimate tolerable heart rate during hypothermia, S′ decreased, probably as a consequence of myocardial hypoperfusion due to sustained ventricular contraction throughout a very short diastole.ConclusionsSystolic function was maintained at physiological heart rates during therapeutic hypothermia. Reduced tolerance to increases in heart rate was caused by lack of ventricular filling due to diastolic dysfunction and shorter diastolic duration.

Survival and complications after interventional bronchoscopy in malignant central airway obstruction: a single-center experience.

Background Patients with malignant airway obstruction may need endobronchial intervention to relieve the associated symptoms. We report our experience of interventional bronchoscopy with regard to complications and survival. Methods A total of 257 patients (167 men, 90 women, median age 67 y) were treated with 360 endobronchial procedures at our department in the period from 1998 to 2009. Kaplan-Meier and Cox regression methods were used for survival analysis. The log-rank test was used for comparison. Results Median survival after interventional bronchoscopy was 15 weeks. Eighteen patients died within 2 weeks after the procedure. Survival in the primary lung and metastatic cancer groups was 15 and 18 weeks, respectively (P=0.25). Survival in patients with small-cell lung carcinoma and nonsmall-cell lung carcinoma was 7 and 17 weeks, respectively (P=0.04). Serious complications such as bleeding (5), pneumothorax (1), and airway obstruction during the procedure (1) were rare (1.9%). All cases of serious hemorrhage occurred in patients with metastases from renal carcinoma. Conclusion Life expectancy in patients with malignant airway obstruction is short. There was no difference in survival between patients with primary and metastatic lung disease. Bronchoscopic treatment is safe and serious complications are rare. Serious hemorrhage is frequent when treating lung metastases from renal carcinoma.