Prevalence of elevated lipoprotein(a) in cardiac rehabilitation patients - results from a large-scale multicentre registry in Germany

BACKGROUND

Lipoprotein(a) (Lp(a)) is an independent risk factor for myocardial infarction and aortic valve stenosis. European guidelines recommend assessing it at least once in a lifetime, particularly in premature atherosclerotic heart disease.

METHODS

A non-interventional registry was conducted at MEDIAN rehabilitation facilities in Germany to assess the frequency of Lp(a) testing in referring acute care hospitals and the prevalence of elevated Lp(a) levels in aortic valve stenosis or premature myocardial infarction. All consecutive patients referred after coronary intervention or aortic valve surgery were included in four cohorts: aortic valve intervention (cohort 1), current/previous myocardial infarction at < 60 years of age (cohorts 2a/2b), and myocardial infarction at ≥ 60 years of age (control).

RESULTS

The analysis included 3393 patient records (cohort 1, n = 1063; cohort 2a, n = 1351; cohort 2b, n = 381; control, n = 598). Lp(a) had been determined at the referring hospital in 0.19% (cohort 1), 4.96% (cohort 2a), 2.36% (cohort 2b), and 2.01% (control) of patients. Lp(a) levels were > 50 mg/dL or > 125 nmol/L in 28.79% (cohort 1), 29.90% (cohort 2a), and 36.48% (cohort 2b; p < 0.001) compared to 24.25% (control). Family history of premature cardiovascular disease was reported in 13.45% (cohort 1), 38.56% (cohort 2a), and 32.81% (cohort 2b) compared to 17.89% (control; p < 0.05 for each comparison).

CONCLUSIONS

Lp(a) had been rarely assessed in acute management of aortic valve stenosis or premature myocardial infarction despite expanding scientific evidence and guideline recommendation. Given the above-average incidence of elevated Lp(a) levels, awareness for Lp(a) has to increase substantially to better identify and manage high-risk patients.

Isolated hemoperfused heart model of slaughterhouse pigs

A model of hemoperfused slaughterhouse pighearts is described providing a wide range of applications which leads to a reduction in animal experiments.

The size of a pigheart, heart rate, coronary perfusion, metabolism, etc. are more comparable to conditions in patients than those in hearts of small laboratory animals.

Global heart function can be assessed either by measuring stroke volume, ejection fraction, Emaxetc. in the working model or by measuring intraventricular pressure with balloon catheters in the isovolumetric model. Regional cardiac function can be measured by sonomicrometry and ischemic and non-ischemic areas can be compared. Local metabolic changes are measurable as well with microdialysis.

Cardiac function can be kept on any given functional level by infusion of norepinephrine in spite of the fact that functional parameters are lower without adrenergic drive in vitro than in vivo.

Stable heart function can be maintained for several hours with only 500 to 1000 ml of blood because the blood is permanently regenerated by a special dialysis system. This model can be applied in many research projects dealing with reperfusion injuries, inotropic, antiarrhythmic or arrhythmogenic effects of certain drugs, immunological rejection, evaluation of imaging systems (NMR, echocardiography etc.) or cardiac assist devices.

Myocardial tissue Doppler echocardiography and N-terminal B-type natriuretic peptide (NT-proBNP) in diastolic and systolic heart failure

Background

The aim of this prospective study was to assess the diagnostic value of NT-proBNP and the concordance with Tissue Doppler Echocardiography (including strain and longitudinal displacement) in diastolic and systolic heart failure.

Methods and results

137 consecutive clinically stable patients were included (42 healthy controls, 43 with diastolic heart failure, 52 with systolic heart failure). In diastolic heart failure, basal septal strain was reduced (-24.8 ± 8.1% vs. controls. -18.5 ± 5.3%, p < 0.0001). In all patients with preserved systolic function, septal basal longitudinal displacement was impaired in patients with increased left-ventricular filling pressures (E/E' < 8: 13.5 mm ± 3.3 mm vs. E/E' > 15: 8.5 mm ± 2.3 mm, p = 0.001) parallel to NT-proBNP elevation (E/E' < 8: 45.8 pg/ml, IQR: 172.5 pg/ml vs. E/E' > 15: 402.0 pg/ml, IQR: 1337.2 pg/ml; p = 0.0007). In ROC analysis, NT-proBNP could detect patients with reduced left ventricular systolic function (LVEF ≥ 55%) with a good diagnostic accuracy. However, the diagnostic accuracy of NT-proBNP to detect diastolic dysfunction was lower.

Conclusion

Subtle changes of longitudinal myocardial function begin in diastolic heart failure and are further increased in systolic heart failure. In patients with preserved LV function, a complex approach with the integration of multiple parameters including Tissue Doppler echocardiography and NT-proBNP is necessary to classify patients.

Circumferential 2D-strain imaging for the prediction of long term response to cardiac resynchronization therapy

BACKGROUND

Cardiac Resynchronization Therapy (CRT) leads to hemodynamic and clinical improvement in heart failure patients. The established methods to evaluate myocardial asynchrony analyze longitudinal and radial myocardial function. This study evaluates the new method of circumferential 2D-strain imaging in the prediction of the long-term response to CRT.

METHODS AND RESULTS

38 heart failure patients (NYHA II-III, QRS > 120 ms, LVEF < 0.35) received CRT and echocardiographic evaluation with a mean follow-up of 9.4 months. 18 (47.4%) of the patients were hemodynamic responders to long-term CRT. In the responder group, the maximum delay in the circumferential 2D-strain in the basal segments decreased (246 +/- 94 to 123 +/- 92 ms, p < 0.001). In the non-responder group there was no significant change (pre CRT: 195 +/- 86, post CRT 135 +/- 136 ms, p = 0.84). This was paralleled by a reduction of the maximum delay in the radial and longitudinal 2D strain in the basal segments. In ROC analysis, the baseline delay of circumferential 2D strain (AUC 0.66 (+/- 0.14)) does not predict a long-term response to CRT (p = 0.37).

CONCLUSION

There is a significant decrease in the circumferential 2D-strain derived delays after CRT, indicating that resynchronization induces improvement in all three dimensions of myocardial contraction. However, the resulting predictive values of 2D strain delays are not superior to longitudinal and radial 2D-strain or TDI delays.

Interventricular septum hematoma during cineventriculography

Background

Intraseptal hematoma and subsequent myocardial infarction due to accidental contrast agent deposition complicating diagnostic cineventriculography is a previously undescribed complication of angiography.

Case presentation

A 61 year old man was admitted at intensive care unit because of unstable angina pectoris 1 hour after coronary angiography. Transthoracic contrast echocardiography showed a non-perfused area in the middle of interventricular septum with an increase of thickening up to 26 mm. Review of cineventriculography revealed contrast enhancement in the interventricular septum after contrast medium injection and a dislocation of the pigtail catheter tip. Follow up by echocardiography and MRI showed, that intramural hematoma has resolved after 6 weeks. After 8 weeks successful stent implantation in LAD was performed and after 6 month the patient had a normal LV-function without ischemic signs or septal thickening demonstrated by stressechocardiography.

Conclusion

A safe and mobile position of the pigtail catheter during ventriculography in the middle of the LV cavity should be ensured to avoid this potentially life-threatening complication. For assessment and absolute measurement of intramural hematoma contrast-enhanced echocardiography is more feasible than MRI and makes interchangeable results.

Noninvasive monitoring of myocardial function after surgical and cytostatic therapy in a peritoneal metastasis rat model: assessment with tissue Doppler and non-Doppler 2D strain echocardiography

Objective

We sought to evaluate the impact of different antineoplastic treatment methods on systolic and diastolic myocardial function, and the feasibility estimation of regional deformation parameters with non-Doppler 2D echocardiography in rats.

Background

The optimal method for quantitative assessment of global and regional ventricular function in rats and the impact of complex oncological multimodal therapy on left- and right-ventricular function in rats remains unclear.

Methods

90 rats after subperitoneal implantation of syngenetic colonic carcinoma cells underwent different onclogical treatment methods and were diveded into one control group and five treatment groups (with 15 rats in each group): group 1 = control group (without operation and without medication), group 2 = operation group without additional therapy, group 3 = combination of operation and photodynamic therapy, group 4 = operation in combination with hyperthermic intraoperative peritoneal chemotherapy with mitomycine, and group 5 = operation in combination with hyperthermic intraoperative peritoneal chemotherapy with gemcitabine, group 6 = operation in combination with taurolidin i.p. instillation. Echocardiographic examination with estimation of wall thickness, diameters, left ventricular fractional shortening, ejection fraction, early and late diastolic transmitral and myocardial velocities, radial and circumferential strain were performed 3–4 days after therapy.

Results

There was an increase of LVEDD and LVESD in all groups after the follow-up period (P = 0.0037). Other LV dimensions, FS and EF as well as diastolic mitral filling parameters measured by echocardiography were not significantly affected by the different treatments. Values for right ventricular dimensions and function remained unchanged, whereas circumferential 2D strain of the inferior wall was slightly, but significantly reduced under the treatment (-18.1 ± 2.5 before and -16.2 ± 2.9 % after treatment; P = 0.001) without differences between the single treatment groups.

Conclusion

It is feasible to assess dimensions, global function, and regional contractility with echocardiography in rats under different oncological therapy. The deformation was decreased under overall treatment without influence by one specific therapy. Therefore, deformation assessment with non-Doppler 2D strain echocardiography is more sensitive than conventional echocardiography for assessing myocardial dysfunction in rats under oncological treatment.

Screening for sleep-related breathing disorders by transthoracic impedance recording integrated into a Holter ECG system

In patients with arrhythmias, coincidence with sleep-related breathing disorders (SRBD) is high and of clinical relevance. Electrocardiogram-derived (ECG) parameters have been developed for SRBD screening, but it has proved necessary to exclude patients with frequent arrhythmias. Holter-based screening tools, easy to use, are therefore warranted. The goal of our study was to evaluate the diagnostic accuracy, with respect to SRBD detection, of transthoracic impedance recording (TTIR) integrated into a Holter System. Our investigation consisted of 2 phases. In phase 1 we compared the performance of TTIR to that of in-hospital polysomnography (PSG) in 56 patients (46 male, mean age 57). In phase 2 we compared TTIR to results from an ambulatory polygraphy (PG) system in 180 patients (143 male, mean age 56). We scored apnea and hypopnea from P(S)G, and derived a respiratory-disturbance index (P(S)G-RDI). TTIR was analyzed semi-automatically. Reduction of the impedance amplitude by more than 50% over 10 s was scored as apnea/hypopnea, with consequent calculation of TTIR-RDI. In phase 1, 20 out of 56 patients revealed a PSG-RDI > 10 h(-1). TTIR-RDI in 19 patients from this group was >10 h(-1) (sensitivity 95%, specificity 97.2%, positive predictive value 95%, negative predictive value 97.2%, interclass correlation coefficient 0.98). In phase 2, 46 of 180 patients revealed a PSG-RDI > 10 h(-1). TTIR-RDI in 37 out of this group was >10 h(-1) (sensitivity 80.4%, specificity 92.5%, positive predictive value 78.7%, negative predictive value 93.2%, interclass correlation coefficient 0.92). TTIR integrated into a Holter ECG system and tested in a large patient cohort demonstrates acceptable high accuracy in detection of SRBD. Arrhythmia analysis and screening for SRBD can be performed in a single-step approch.

Thoracic spinal cord stimulation improves functional status and relieves symptoms in patients with refractory angina pectoris: the first placebo-controlled randomised study

BACKGROUND

Spinal cord stimulation (SCS) is an alternative treatment option for refractory angina. Controlled trials demonstrate symptom relief and improvement in functional status. Since patients experience retrosternal prickling during active SCS, there is no option for blinding patients to active treatment or for placebo control.

OBJECTIVE

To examine the therapeutic effects of subthreshold SCS in patients with refractory angina in a placebo-controlled study.

METHODS

12 responders to treatment who had already been treated with SCS for refractory angina were enrolled. Patients were randomised into four consecutive treatment arms, each for 4 weeks, with various stimulation timing and output parameters: 3 x 2 h/day (phase A) and 24 h/day with conventional output (phase B); 3 x 2 h/day with a subthreshold output (phase C); and 24 h/day with 0.1 V output, which served as control (phase D). Functional status, quality of life, Canadian Cardiovascular Society classification and nitrate usage were assessed at the end of each 4-week period.

RESULTS

In phase D, patients showed a significant reduction in walking distance compared with phases A and C. Canadian Cardiovascular Society classification worsened in phase D compared with phases A-C. Frequency of angina attacks and the visual analogue scale were significantly worse in phase D than in phases A-C. In three patients, it was necessary to prematurely terminate phase D owing to intolerable angina attacks.

CONCLUSIONS

In this first placebo-controlled trial to apply SCS in patients with refractory angina, improvement in functional status and symptoms was revealed in phases with conventional or subthreshold stimulation, in comparison to a low-output (placebo) phase.

Pacemaker-Induced Superior Vena Cava Syndrome: Clinical Evaluation of Long-Term Follow-Up

BACKGROUND

Pacemaker-induced superior vena cava (SVC) syndrome is a rare but serious complication of permanent pacemaker implantation. Because of its rarity, little is known about the long-term prognoses of such patients.

METHODS

Five patients, mean age 62 +/- 11.4 years, with pacemaker-induced SVC syndrome for more than 10 years were investigated. The clinical evaluation included: exercise testing, thrombophilia lab tests, and a chest CT.

RESULTS

Two of the patients manifested complications of SVC syndrome which included thoracoabdominal subcutaneous collaterals. One of these patients simultaneously developed an increase in the pacing threshold which required the implantation of epicardial leads. Three of the five patients had normal age-adjusted VO(2) AT und VO(2) max. Four of the patients were both heterozygous for a polymorphism of PAI-1 and were homozygous for a polymorphism of t-PA. One of these patients also was heterozygous for a polymorphism of factor V and glycoprotein IIb/IIIa. The chest CTs revealed extensive and varying collateral circulation patterns in all of the patients.

CONCLUSIONS

The development of pacemaker-induced SVC syndrome is the result of various predisposing factors including thrombophilia. Many patients retain normal age-adjusted cardiopulmonary capacity and demonstrate stable clinical findings on the long-term as the result of the development of extensive collateral vessel systems. The most serious complication was the combination of SVC syndrome and the simultaneous malfunctioning of one of the leads requiring implantation of a new lead.

Evaluation of Global and Regional Left Ventricular Function With 16-Slice Computed Tomography, Biplane Cineventriculography, and Two-Dimensional Transthoracic Echocardiography

OBJECTIVES

We sought to compare left ventricular (LV) function assessed with multislice computed tomography (MSCT), biplane cineventriculography (CVG), and transthoracic echocardiography (Echo), with magnetic resonance imaging (MRI) as the reference standard.

BACKGROUND

With the same data as acquired for noninvasive coronary angiography, MSCT enables registration of myocardial function.

METHODS

A total of 88 patients (64 men and 24 women) underwent MSCT with 16 x 0.5 mm detector collimation, CVG, and MRI, whereas Echo was retrospectively analyzed in a subset of 30 patients.

RESULTS

Regarding the ejection fraction, the agreement was significantly superior for MSCT than for CVG (+/- 10.2% vs. +/- 16.8%; p < 0.001) and Echo (+/- 11.0% vs. +/- 21.2%; p < 0.001). For the end-diastolic and end-systolic volumes, the limits of agreement with CVG (p < 0.001) and Echo (p < 0.001 and p < 0.02, respectively) were also significantly larger than with MSCT. In comparison with MSCT, CVG significantly overestimated the end-diastolic and end-systolic volumes (p < 0.001). Intraobserver analysis of MSCT yielded limits of agreement for ejection fraction (+/- 4.8%), end-diastolic volume (+/- 15.6 ml) and end-systolic volume (+/- 8.0 ml), and myocardial mass (+/- 18.2 g). The accuracy in identifying patients and myocardial segments with abnormal regional function was significantly higher with MSCT (84% and 95%) than with CVG (63% and 90%; p < 0.002 and p < 0.001), whereas MSCT and Echo were not significantly different in identifying patients with abnormal regional function.

CONCLUSIONS

Our results indicate that the assessment of global and regional LV function with MSCT is more accurate than with CVG, whereas MSCT is superior to Echo for global function. This suggests that MSCT allows reliable evaluation of global and regional LV function.

Right ventricular function assessed by two-dimensional strain and tissue Doppler echocardiography in patients with pulmonary arterial hypertension and effect of vasodilator therapy

Two-dimensional strain echocardiography is a new method for the assessment of regional contractility. Thirty-seven patients with pulmonary arterial hypertension (mean age 56.4 +/- 11 years) and 38 normal subjects (mean age 58.3 +/- 12 years) underwent 2-dimensional echocardiography and tissue Doppler echocardiographic evaluation of right ventricular (RV) global function and regional contractility. Patients with pulmonary arterial hypertension additionally underwent 6-minute walking distance tests and right-sided cardiac catheterization before and after (8 +/- 3 months) vasodilator therapy. Moderate or severe RV dysfunction was present in all patients (2-dimensional strain of the basal segment of the RV free wall: -8.8 +/- 4.1% systolic longitudinal deformation) compared with normal subjects (-24.3 +/- 4.7% systolic longitudinal deformation, p < 0.001) and was improved with vasodilator therapy after 6 to 11 months (-13.3 +/- 6.2% systolic longitudinal deformation, p < 0.001).

[Echocardiographic evaluation to select patients for cardiac resynchronization therapy]

Wide QRS complex and asynchronous myocardial contraction in heart failure are associated with poor prognosis. Resynchronization can be achieved by biventricular pacing (BVP), which leads to hemodynamic and clinical improvement and reverse remodeling, and may improve survival. However, there is a substantial subset of patients with wide QRS complexes in the electrocardiogram who does not improve despite BVP, and there are findings which suggest that resynchronization therapy may be also beneficial for heart failure patients with normal QRS duration. QRS width predicts the benefit of BVP only with limitation and only correlates weakly with echocardiographically determined myocardial asynchrony. Determination of asynchrony by tissue Doppler echocardiography seems to be the best predictor for improvement after BVP, although no consensus on the optimal method to assess asynchrony has yet been achieved. To date, most studies evaluating tissue Doppler echo in BVP were performed retrospectively and only one prospective study with patient selection for BVP according to echocardiography and electrocardiography criteria of asynchrony has been published. These new echocardiographic tools will help to prospectively select patients for BVP, help to guide implantation and to optimize device programming.

Long-term therapy of interferon-alpha induced pulmonary arterial hypertension with different PDE-5 inhibitors: a case report

BACKGROUND

Interferon alpha2 is widely used in hepatitis and high-risk melanoma. Interferon-induced pulmonary arterial hypertension as a side effect is rare.

CASE PRESENTATION

We describe a melanoma patient who developed severe pulmonary arterial hypertension 30 months after initiation of adjuvant interferon alpha2b therapy. Discontinuation of interferon did not improve pulmonary arterial hypertension. This patient could be treated successfully with phosphodiesterase-5 inhibitor therapy.

CONCLUSION

This is only the 5th case of interferon-induced pulmonary arterial hypertension and the first documented case where pulmonary arterial hypertension was not reversible after termination of interferon alpha2 therapy. If interferon alpha2 treated patients develop respiratory symptoms, pulmonary arterial hypertension should be considered in the differential diagnosis. For these patients phosphodiesterase-5 inhibitors, e.g. sildenafil or vardenafil, could be an effective therapeutic approach.

Does contrast echocardiography induce increases in markers of myocardial necrosis, inflammation and oxidative stress suggesting myocardial injury?

Background

Contrast echocardiography is a precise tool for the non-invasive assessment of myocardial function and perfusion. Side effects of contrast echocardiography resulting from contrast-agent induced myocardial micro-lesions have been found in animals. The goal of this study is to measure markers of myocardial necrosis, inflammation and oxidative stress in humans to evaluate potential side-effects of contrast echocardiography.

Methods

20 patients who underwent contrast echocardiography with Optison as the contrast medium were investigated. To evaluate myocardial micro-necrosis, inflammation and oxidative stress, cardiac troponin I (cTnI), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, -8 and thiobarbituric acid reactive substances (TBARS) were measured at baseline and at 2, 4, 8 and 24 hours after contrast echocardiography.

Results

At baseline, 50% of the patients had cTnI and TBARS values outside the reference range. TNF-α, IL-6, IL-8 levels were within the reference range. Patients with cTnI above the RR clustered to significantly higher levels of TNF-α and IL-6. After contrast echocardiography, no statistically significant increase of cTnI, cytokines and TBARS was found. However, for nearly 50% of the patients, the intra-individual cTnI kinetics crossed the critical difference (threefold of methodical variation) which indicates a marker increase. This was neither predicted by the baseline levels of the cytokines nor the markers of oxidative stress.

Conclusion

There are no clinically relevant increases in serum markers for micro-necrosis, inflammation and oxidative stress in humans after contrast echocardiography. Future studies have to address whether cTnI increase in some patients represent a subset with increased risk for side effects after contrast echocardiography.

High concordance of invasive and echocardiographic mean pressure gradients in patients with a mechanical aortic valve prosthesis

BACKGROUND AND AIM OF THE STUDY

Conflicting data exist regarding the accuracy of echocardiographic Doppler gradients compared to invasive pressure gradients in the hemodynamic assessment of patients with prosthetic aortic valves. The study aim was to determine the correlation between these measurements for mechanical single- and double-leaflet aortic valve prostheses in vivo.

METHODS

Forty-four patients with an aortic valve prosthesis were included in this prospective study. Transthoracic echocardiography was performed immediately before the invasive measurements. Left ventricular pressure measurements were achieved by either atrial transseptal puncture and antegrade, transmitral left ventricular catheterization or--in the case of mitral valve replacement--direct left ventricular puncture.

RESULTS

Comparison of echocardiographic and invasive mean pressure gradients of all examined aortic prosthetic valves revealed a Pearson correlation r = 0.59 (p < 0.001). The mean pressure gradient was overestimated by 7.4 mmHg with echocardiography. Classifying patients into clinically relevant categories (mild, moderate, severely increased pressure gradient) resulted in a kappa value of 0.72 and an agreement of 86.4%. There was no relevant difference between single- and double-leaflet valves.

CONCLUSION

A high concordance was found between echocardiographic and invasive mean pressure gradients in vivo. Invasive measurements of the prosthetic valve gradients therefore seem to be indicated only in patients with contradictory echocardiographic and clinical findings.

Tissue Doppler echocardiography and biventricular pacing in heart failure: patient selection, procedural guidance, follow-up, quantification of success

Asynchronous myocardial contraction in heart failure is associated with poor prognosis. Resynchronization can be achieved by biventricular pacing (BVP), which leads to clinical improvement and reverse remodeling. However, there is a substantial subset of patients with wide QRS complexes in the electrocardiogram that does not improve despite BVP. QRS width does not predict benefit of BVP and only correlates weakly with echocardiographically determined myocardial asynchrony. Determination of asynchrony by Tissue Doppler echocardiography seems to be the best predictor for improvement after BVP, although no consensus on the optimal method to assess asynchrony has been achieved yet. Our own preliminary results show the usefulness of Tissue Doppler Imaging and Tissue Synchronization Imaging to document acute and sustained improvement after BVP. To date, all studies evaluating Tissue Doppler in BVP were performed retrospectively and no prospective studies with patient selection for BVP according to echocardiographic criteria of asynchrony were published yet. We believe that these new echocardiographic tools will help to prospectively select patients for BVP, help to guide implantation and to optimize device programming.

Percutaneous closure of interatrial communications in adults - prospective embolism prevention study with two- and three-dimensional echocardiography

BACKGROUND

Patients with interatrial communications after paradoxical embolic events are at risk for recurrent thromboembolism. We hypothesized that transcatheter closure of the defects would result in long-term prevention of systemic embolism and performed clinical and echocardiographic follow-up.

METHODS

We included 161 patients (mean age 46.8 +/- 11 years, 83 females) with patent foramen ovale or atrial septal defect and at least one documented paradoxical systemic thrombembolic event and/or a large atrial shunting.

RESULTS

The implantation procedure was successfully performed without major complications in all patients and minor complications in 2.5%. Two and / or three dimensional echocardiography was performed before and after 4 weeks and 12 months using a multiplane transoesophageal probe. After 4 weeks and 6 months two patients had minimal shunting. These residual defects were closed with a second device implantation without shunting after further 4 weeks. During a follow-up of 324.3 patient years (range, 13 to 19 months), recurrent embolic events occurred in only 1 patient (0.6%).

CONCLUSION

After primary paradoxical systemic embolism, results of transcatheter occlusion of the interatrial communications are dependent on the closure device system and can prevent further secondary embolic events for up to 1 year after the percutaneous closure. Three dimensional echocardiography provides dynamic features of the defects and the post closure status and may lead to an improved understanding and diagnosis of the interatrial defect.

Influence of transmyocardial laser revascularization (TMLR) on regional cardiac function and metabolism in an isolated hemoperfused working pig heart

The mechanism of an indirect revascularization in ischemic myocardium by transmyocardial laser revascularization (TMLR) is not yet fully understood. An improvement of clinical symptoms caused by TMLR is reported in many clinical trials with patients in which a direct revascularization is not possible. An increase of myocardial perfusion through laser channels is doubtful, because the myocardial pressure in the wall is higher than in the cavum. Therefore we measured the local cardiac function (intramyocardial pressure, wall thickness, pressure-length curves) and acute metabolic changes (tissue lactate content, tissue pO2) in ischemic and nonischemic regions before and after TMLR in isolated hemoperfused pig hearts. An isolated heart was chosen because it enabled us to separate coronary flow from flow through ventricular channels. The ischemia was induced by coronary occlusion or microembolization (eight hearts each). It should be noted that microembolization leads to conditions which are more comparable with those found in patients selected for TMLR. In the isolated working heart, the coronary perfusion can be controlled independently from perfusion through the ventricular cavum. Under the ischemic conditions mentioned above, we observed that the intramyocardial pressure in the ischemic region decreased below the left ventricular pressure, so one premise for indirect perfusion was met. TMLR after microembolization led to a significant improvement of regional cardiac work and the tissue oxygen pressure. These acute effects demonstrate the possibility of functional and metabolic amelioration by TMLR after ischemia induced by microembolization in an isolated hemoperfused pig heart.

Isolated hemoperfused heart model of slaughterhouse pigs

A model of hemoperfused slaughterhouse pighearts is described providing a wide range of applications which leads to a reduction in animal experiments. The size of a pigheart, heart rate, coronary perfusion, metabolism, etc. are more comparable to conditions in patients than those in hearts of small laboratory animals. Global heart function can be assessed either by measuring stroke volume, ejection fraction, Emax etc. in the working model or by measuring intraventricular pressure with balloon catheters in the isovolumetric model. Regional cardiac function can be measured by sonomicrometry and ischemic and non-ischemic areas can be compared. Local metabolic changes are measurable as well with microdialysis. Cardiac function can be kept on any given functional level by infusion of norepinephrine in spite of the fact that functional parameters are lower without adrenergic drive in vitro than in vivo. Stable heart function can be maintained for several hours with only 500 to 1000 ml of blood because the blood is permanently regenerated by a special dialysis system. This model can be applied in many research projects dealing with reperfusion injuries, inotropic, antiarrhythmic or arrhythmogenic effects of certain drugs, immunological rejection, evaluation of imaging systems (NMR, echocardiography etc.) or cardiac assist devices.