Increased 18F-PSMA and 18F-FDG Uptake in Lipomatous Hypertrophy of the Interatrial Septum.

ABSTRACT: Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign anomaly with low prevalence. Lipomatous hypertrophy of the interatrial septum is asymptomatic in most of the cases and rarely leads to atrial arrhythmias, obstructive flow symptoms, or sudden death. It is mostly diagnosed as an incidental finding in cross-sectional imaging and echocardiography, and increased 18F-FDG uptake on LHIS has been described. We present a case of repeated increased 18F-PSMA uptake in LHIS. Although very rare, familiarity with the typical features and prevalence of LHIS in PET/CT can avoid misinterpretation for metastatic disease.

Sex-related differences in left ventricular remodeling and outcome after alcohol septal ablation in hypertrophic obstructive cardiomyopathy: insights from cardiovascular magnetic resonance imaging.

BACKGROUND: Alcohol septal ablation (ASA) has been proven to reverse left ventricular (LV) remodeling in hypertrophic cardiomyopathy (HCM). However, there are no studies on the effect of sex on LV remodeling after ASA. We aimed to investigate whether sex differences affect the process of LV remodeling and outcome after ASA. METHODS: A total of 107 patients with obstructive HCM (54 men and 53 women, mean age 51 ± 8 years) were recruited. Cardiovascular magnetic resonance (CMR) was performed at baseline and 16 months after ASA. The extent of late gadolinium enhancement (LGE) was measured. RESULTS: Women had a higher indexed LV mass and smaller indexed LV end-systolic volumes than men at the time of ASA. After ASA, both men and women exhibited a regression of LV mass, and the percentage of mass regression was greater in men than women (15.3% ± 4.3% vs. 10.7% ± 1.8%, p < 0.001). In multivariable analysis, male sex, higher reduction of LV outflow tract (LVOT) gradient and lower baseline LV mass index were independently associated with greater LV mass regression after ASA. Kaplan-Meier analysis showed significantly higher cardiovascular events in women than in men (p = 0.015). Female sex [hazard ratio (HR) 3.913, p = 0.038] and LV mass preablation (HR, 1.019, p = 0.010) were independent predictors of cardiovascular outcomes. CONCLUSIONS: Males with HCM had favorable reverse remodeling with greater LV mass regression post-ASA than female patients. This favorable LV reverse remodeling might provide a mechanistic explanation for the survival advantage in men.

Effects of Septal Reduction Therapy on Acute Cardiovascular Events and All-Cause Mortality in Patients with Hypertrophic Cardiomyopathy.

Septal reduction therapy (SRT) -i.e. septal myectomy and alcohol septal ablation-has been performed to treat medically refractory hypertrophic cardiomyopathy (HCM) for decades. However, it is largely unknown whether SRT prevents HCM-related cardiovascular events or death. The objective was to examine the effects of SRT on acute cardiovascular events and all-cause mortality in HCM. We performed a propensity score (PS) -matched study using databases that capture all hospitalizations and outpatient visits in New York state. We identified patients with HCM who underwent SRT between 2007 and 2014 (i.e. the SRT group) and those who had never had SRT but had at least one hospitalization for HCM during the same period (i.e. the control group). We performed PS matching at a 1:1 ratio. The primary outcome was a composite of acute cardiovascular events and all-cause mortality during 0-180 days and 181-360 days. The secondary outcome was 180- and 360-day all-cause mortality. We included 846 patients with HCM (423 PS-matched pairs). Patients who underwent SRT had a lower risk of the primary outcome event (0-180 days: odds ratio [OR], 0.54; 95% confidence intervals (CI), 0.37-0.80; P = 0.002 and 181-360 days: OR, 0.33; 95% CI, 0.22-0.51; P < 0.0001). Furthermore, the risk of all-cause mortality was lower at 180 days (OR, 0.37; 95% CI, 0.22-0.63; P = 0.0003) and 360 days post-SRT (OR, 0.32; 95% CI, 0.20-0.51; P < 0.0001). In conclusion, our PS-matched study using population-based datasets demonstrated that SRT was associated with a reduced risk of a composite of acute cardiovascular events and all-cause mortality in HCM during the first post-SRT year.

Sleep Disordered Breathing and Mortality in Patients With Hypertrophic Obstructive Cardiomyopathy Undergoing Septal Myectomy.

OBJECTIVE: To determine the impact of sleep-disordered breathing (SDB) on survival in patients with hypertrophic cardiomyopathy (HCM) following septal myectomy. PATIENTS AND METHODS: Patients with obstructive HCM undergoing septal myectomy from 2007 to 2016 were reviewed. Those who had an overnight oximetry test within 6 months before myectomy were included in analysis. Oxygen desaturation index was examined continuously and also categorically (SDB [>5/h] and severe SDB [>15/h]). RESULTS: A total of 619 of 1500 patients undergoing septal myectomy had overnight oximetry tests. Sleep-disordered breathing (oxygen desaturation index >5/h) was identified in 338 (54.6%) patients, and among those patients, 117 (18.9%) were classified as severe. Patients with SDB were older, had greater body mass index and body surface area, were more likely to have arterial hypertension and atrial fibrillation, and had an increased E/e' ratio on Doppler echocardiography. Notably, there was no difference in preoperative resting left ventricular outflow tract pressure gradient between patients with SDB and those with normal overnight oximetry (55 (interquartile range: 25 to 86) mm Hg versus 52 (interquartile range: 21 to 85) mm Hg; P=.29). There was no difference in age-adjusted survival among patients with normal oximetry compared with those with mild SDB (hazard ratio: 0.98; 95% CI: 0.45 to 2.17), and severe SDB (hazard ratio: 1.06, 95% CI 0.42 - 2.71). CONCLUSION: Sleep-disordered breathing is present in more than half of patients with obstructive HCM in whom septal myectomy is indicated, and is mainly associated with aging, overweight, and male sex. However, SDB does not alter survival following septal myectomy.

Routine histopathology of septal myectomy for hypertrophic obstructive cardiomyopathy in a greek cohort.

Hypertrophic cardiomyopathy (HCM) is a diverse inherited disease affecting 1 in 500 individuals irrespective of gender and ethnicity. A fraction of HCM patients will eventually develop drug refractory dynamic obstruction of the left ventricular outflow tract. For such patients, septal myectomy is the procedure of choice to alleviate their symptoms and improve their quality of life. The current histopathological study, the first from the Greek region, aims to examine the hallmark histopathological characteristics of Hypertrophic Obstructive Cardiomyopathy in a population of patients undergoing septal myectomy at a single center over a ten year period. Medical records and histopathology specimens of thirty nine (n=39) patients were evaluated. The sample comprised 22 males (56.4%) and 17 females (43.6%). Mean patient age at myectomy was 53.9±16.7 years, ranging from 12 to 79 years. Maximal IVS thickness on echocardiography was available for 35 patients with a median value of 2.08cm. Peak resting LVOT Pressure Gradient was available for 33 patients with a mean value of 104.88±44.20 mmHg. Central tendency of each histopathological attribute expressed as the median value was: moderate for myocyte hypertrophy, mild for cytoplasmic vacuolization, moderate for subendocardial fibrosis, moderate for interstitial fibrosis, mild for replacement fibrosis, moderate for myofibrillar disarray and mild for capillary stenosis. Myocyte hypertrophy, present in all specimens, was positively correlated with maximal IVS thickness (tau-b=0.43, p=0.002). Replacement fibrosis was positively correlated with the grade of microvascular stenosis (tau-b=0.45, p=0.004). LVEF was negatively correlated with the grade of interstitial fibrosis (tau-b=-0.43, p=0.035) and with the extent of myocardial fiber disarray (tau-b=-0.42, p=0.034). Histopathological attributes were not correlated with patient gender or age thus proving that HCM has a histological phenotype unique to each patient, mainly depending on each specific sarcomeric mutation.

Prognostic value of cardiac magnetic resonance septal late gadolinium enhancement patterns for periaortic ventricular tachycardia ablation: Heterogeneity of the anteroseptal substrate in nonischemic cardiomyopathy.

BACKGROUND: Ventricular tachycardia (VT) from the anteroseptal subtype of nonischemic cardiomyopathy has a high probability of recurrence after catheter ablation. OBJECTIVE: The purpose of this study was to determine the predictive value of septal scar patterns by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) on ablation outcomes in patients with VT arising from an anteroseptal substrate. METHODS: Patients with periaortic VT arising from an anteroseptal substrate with preprocedural wideband LGE-CMR were divided into 2 groups by the degree of longitudinal septal LGE extension as full-length septal (≥80% anteroposterior length) or partial septal (<80% anteroposterior length). Septal LGE volumes were quantified in those with and without VT recurrence. RESULTS: Among 234 patients referred for scar-related VT ablation between 2017 and 2020, 25 patients (92% male; age 64 ± 8 years) and a total of 108 VTs were analyzed. A greater number of VT morphologies were induced in patients with full-length septal LGE compared to partial septal LGE (median [interquartile range]: 5 [3-9] vs 2 [1-4]; P = .005). Patients with VT recurrence had larger septal LGE volumes compared to those without recurrence (11.4 mL [8.8-13.9] vs 4.2 mL [0-9.5]; P = .012). At median follow-up of 16 months (5-22), overall freedom from VT recurrence was 52% and significantly higher in patients with partial septal LGE than in those with full-length septal LGE (80% vs 20%; P = .005). CONCLUSION: VT originating from an anteroseptal substrate is associated with heterogeneous patterns and extent of CMR septal scar. Preprocedural imaging may substratify this challenging patient population for the propensity for multiple induced VT morphologies and recurrence after catheter ablation.

THE PLACE OF CARDIAC COMPUTED TOMOGRAPHY IN PREOPERATIVE PLANNING OF EXTENDED SEPTAL MYECTOMY IN PATIENTS WITH OBSTRUCTIVE FORM OF HYPERTROPHIC CARDIOMYOMATHY. / MISTsE SERTsEVOÏ KOMP'IuTERNOÏ TOMOGRAFIÏ V PEREDOPERATsIINOMU PLANUVANNI ROZShYRENOÏ SEPTAL'NOÏ MIEKTOMIÏ U PATsIIeNTIV Z OBSTRUKTYVNOIu FORMOIu GIPERTROFIChNOÏ KARDIOMIOPATIÏ.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy. Extended septalmyectomy (ESM) is one of the priority methods of treatment of drug-refractory obstructive HCM. In recent years,hospital mortality during surgical correction of obstructive HCM in expert centers does not exceed 1-2 %. However,typical threatening complications of septal myectomy, such as iatrogenic ventricular septal defect (VSD) and rupture of the anterior or posterior walls of the left ventricle (LV), remain a topical issue in surgery of HCM. OBJECTIVE: to show the role of preoperative CT-planning to predict and reduce possible technical problems associated with ESM, including iatrogenic VSD. METHODS AND MATERIALS: This study includes 217 symptomatic patients with obstructive HCM, who from April 2016to October 2019 as one of the steps of preoperative planning underwent cardiac CT prior to ESM. Cardiac CT was performed to delineate the left ventricular myocardium, assess the distribution of hypertrophy and the presence ofcrypts. Special attention was also paid to the anatomy of the mitral valve (MV) and subvalvular apparatus. Coronaryartery patency was assessed by CAD-RADS, a standardized method for reporting the results of coronary CT angiography to determine tactics for further management of the patient. RESULTS AND DISCUSSION: In the study group, the average age of patients was (49 ± 15) years, 48 % - men. All patientshad a symptomatic, drug-refractory obstructive form of HCM. The mean maximum wall thickness of the interventricular septum (IVS) was (20 ± 5) mm (range 16-33). The average LV mass was (118 ± 23) g/m2. 195 patients (89.9 %)had systolic anterior motion ( SAM) of the MV. MV and subvalvular apparatus anomalies were detected in 62 patients(28.6 %). A zone of scarring and regression of IVS after alcohol septal ablation (ASA) was detected in 7 patients(0.3 %) with residual LV outflow gradient. Coronary arteries atherosclerosis was detected in 32 patients (14.7 %). CONCLUSIONS: Preoperative CT-planning of septal myectomy allows to obtain information on morphology of the LV,IVS, MV and subvalvular apparatus, and gives the surgeon the advantage to form a more accurate plan for the location and volume of septal resection, and avoid complications when correcting obstructive HCM. No iatrogenic VSDwas detected in any of the patient in the study group.

Cardiac magnetic resonance in hypertrophic and dilated cardiomyopathies.

Cardiomyopathies are a heterogeneous entity. The progress in the field of genetics has allowed over the years to determine its origin more and more often. The classification of these pathologies has changed over the years; it has been updated with new knowledge. Imaging allows to define the phenotypic characteristics of the different forms of cardiomyopathy. Cardiac magnetic resonance (CMR) allows a morphological evaluation of the associated (and sometimes pathognomonic) cardiac findings of any form of cardiomyopathy. The tissue characterization sequences also make magnetic resonance imaging unique in its ability to detect changes in myocardial tissue. This review aims to define the features that can be highlighted by CMR in hypertrophic and dilated forms and the possible differential diagnoses. In hypertrophic forms, CMR provides: precise evaluation of wall thickness in all segments, ventricular function and size and evaluation of possible presence of areas of fibrosis as well as changes in myocardial tissue (measurement of T1 mapping and extracellular volume values). In dilated forms, cardiac resonance is the gold standard in the assessment of ventricular volumes. CMR highlights also the potential alterations of the myocardial tissue.

SHROOM3 is downstream of the planar cell polarity pathway and loss-of-function results in congenital heart defects.

Congenital heart disease (CHD) is the most common birth defect, and the leading cause of death due to birth defects, yet causative molecular mechanisms remain mostly unknown. We previously implicated a novel CHD candidate gene, SHROOM3, in a patient with CHD. Using a Shroom3 gene trap knockout mouse (Shroom3gt/gt) we demonstrate that SHROOM3 is downstream of the noncanonical Wnt planar cell polarity signaling pathway (PCP) and loss-of-function causes cardiac defects. We demonstrate Shroom3 expression within cardiomyocytes of the ventricles and interventricular septum from E10.5 onward, as well as within cardiac neural crest cells and second heart field cells that populate the cardiac outflow tract. We demonstrate that Shroom3gt/gt mice exhibit variable penetrance of a spectrum of CHDs that include ventricular septal defects, double outlet right ventricle, and thin left ventricular myocardium. This CHD spectrum phenocopies what is observed with disrupted PCP. We show that during cardiac development SHROOM3 interacts physically and genetically with, and is downstream of, key PCP signaling component Dishevelled 2. Within Shroom3gt/gt hearts we demonstrate disrupted terminal PCP components, actomyosin cytoskeleton, cardiomyocyte polarity, organization, proliferation and morphology. Together, these data demonstrate SHROOM3 functions during cardiac development as an actomyosin cytoskeleton effector downstream of PCP signaling, revealing SHROOM3's novel role in cardiac development and CHD.

Management of Septal Branch Perforation and Septal Hematoma During Retrograde Treatment of Coronary Chronic Total Occlusion Using Fat Embolization.

Septal vessel perforation followed by septal hematoma is a rare complication of retrograde approach for treatment of coronary chronic total occlusions, possibly leading to septal rupture. We report 2 cases of patients with septal vessel perforation and subsequent hematoma successfully treated with autologous fat embolization. Such technique is inexpensive, omnipresent, and relatively easy to perform.

Cardiac Malignant Peripheral Nerve Sheath Tumor Accessed By 18F-FDG PET/CT.

This is a case report of a patient presenting an extremely rare cardiac malignancy: malignant peripheral nerve sheath tumour. The 18F-fluorodeoxyglucosis positron emission tomography associated to computed tomography (18F-FDG PET/CT) accesses the tumour anatomy and metabolic activity, thereby making it possible to characterize a malignant neoplasm noninvasively. The diagnostic approach with 18F-FDG PET/CT spared the heart from a likely futile invasive procedure when detecting a distant metastasis and changed the biopsy site and therapeutic planning.

Lipomatous hypertrophy of the interatrial septum is a pathologic, not an anatomic diagnosis.

BACKGROUND AND AIM: Lipomatous hypertrophy of the interatrial septum (LHIS), a fatty tumor, is usually diagnosed on both echo and CT/MRI imaging. Cases of LHIS located outside of the interatrial septum are extremely rare and rarer still are these cases large enough to cause symptoms. The clinical literature demonstrates a misunderstanding that fatty tumors outside the intra-atrial area represent lipomas. However, pathologic understanding of these fatty tumors is clear and is based on microscopic findings. METHODS: The tumor was removed by diving the base of attachment at the left ventricular apex via a median sternotomy on cardiopulmonary bypass. RESULTS: The patient made an uneventful recovery and remains well at 6 months postoperatively. CONCLUSIONS: On rare occasions, LHIS can arise from outside the interatrial septum. An LHIS can be differentiated from a lipoma by the presence of entrapped cardiac myocytes in LHIS, making it a pathological, rather than an anatomic, diagnosis.

Short-Term Hemodynamic and Electrophysiological Effects of Cardiac Resynchronization by Left Ventricular Septal Pacing.

BACKGROUND: Cardiac resynchronization therapy (CRT) is usually performed by biventricular (BiV) pacing. Previously, feasibility of transvenous implantation of a lead at the left ventricular (LV) endocardial side of the interventricular septum, referred to as LV septal (LVs) pacing, was demonstrated. OBJECTIVES: The authors sought to compare the acute electrophysiological and hemodynamic effects of LVs with BiV and His bundle (HB) pacing in CRT patients. METHODS: Temporary LVs pacing (transaortic approach) alone or in combination with right ventricular (RV) (LVs+RV), BiV, and HB pacing was performed in 27 patients undergoing CRT implantation. Electrophysiological changes were assessed using electrocardiography (QRS duration), vectorcardiography (QRS area), and multielectrode body surface mapping (standard deviation of activation times [SDAT]). Hemodynamic changes were assessed as the first derivative of LV pressure (LVdP/dtmax). RESULTS: As compared with baseline, LVs pacing resulted in a larger reduction in QRS area (to 73 ± 22 µVs) and SDAT (to 26 ± 7 ms) than BiV (to 93 ± 26 µVs and 31 ± 7 ms; both p < 0.05) and LVs+RV pacing (to 108 ± 37 µVs; p < 0.05; and 29 ± 8 ms; p = 0.05). The increase in LVdP/dtmax was similar during LVs and BiV pacing (17 ± 10% vs. 17 ± 9%, respectively) and larger than during LVs+RV pacing (11 ± 9%; p < 0.05). There were no significant differences between basal, mid-, or apical LVs levels in LVdP/dtmax and SDAT. In a subgroup of 16 patients, changes in QRS area, SDAT, and LVdP/dtmax were comparable between LVs and HB pacing. CONCLUSIONS: LVs pacing provides short-term hemodynamic improvement and electrical resynchronization that is at least as good as during BiV and possibly HB pacing. These results indicate that LVs pacing may serve as a valuable alternative for CRT.

Effect of cardiac resynchronization therapy on septal perfusion and septal thickening: Association with left ventricular function, reverse remodelling and dyssynchrony.

BACKGROUND: We evaluated the effect of cardiac resynchronization therapy (CRT) on septal perfusion and thickening at 6 months post implantation assessed on Tc99m-MIBI Gated myocardial perfusion SPECT (GMPS).We also studied the association of change in septal perfusion and thickening with primary outcome defined as at least one [improvement in ≥1NYHA class, left ventricular ejection fraction (LVEF) by ≥ 5%, reduction of end-systolic volume (ESV) by ≥ 15%, and improvement ≥ 5 points in Minnesota living with heart failure questionnaire (MLHFQ)]. METHOD: One hundred and five patients underwent clinical and GMPS evaluation before and at 6 months post CRT. RESULT: Post CRT there was significant improvement in mean normalized septal perfusion uptake and in septal thickening (P value = 0.001, both). There was no significant relation between improvement in septal perfusion and primary outcome. However, improvement in septal thickening was statistically significant with favorable primary outcome (P = 0.001).There was no significant correlation between improvement of septal perfusion and improvement in LVEF, reduction in End diastolic volume (EDV), ESV, and Left ventricular Dyssynchrony (LVD). But, there was significant correlation between improvement of septal thickening and these parameters. CONCLUSION: Improvement in septal thickening was associated with reverse remodeling, improvement in LVEF, and reduction of LVD.

Stereotactic body radiotherapy for ventricular tachycardia (cardiac radiosurgery) : First-in-patient treatment in Germany.

PURPOSE: Single-session cardiac stereotactic body radiotherapy, called cardiac radiosurgery (CRS) or radioablation (RA), may offer a potential treatment option for patients with refractory ventricular tachycardia (VT) and electrical storm who are otherwise ineligible for catheter ablation. However, there is only limited clinical experience. We now present the first-in-patient treatment using (CRS/RA) for VT in Germany. METHODS: A 78-year-old male patient with dilated cardiomyopathy and significantly reduced ejection fraction (15%) presented with monomorphic VT refractory to poly-anti-arrhythmic medication and causing multiple implantable cardioverter-defibrillator (ICD) interventions over the course of several weeks, necessitating prolonged treatment on an intensive care unit. Ultra-high-resolution electroanatomical voltage mapping (EVM) revealed a re-entry circuit in the cardiac septum inaccessible for catheter ablation. Based on the EVM, CRS/RA with a single session dose of 25 Gy (83% isodose) was delivered to the VT substrate (8.1 cc) using a c-arm-based high-precision linear accelerator on November 30, 2018. RESULTS: CRS/RA was performed without incident and dysfunction of the ICD was not observed. Following the procedure, a significant reduction in monomorphic VT from 5.0 to 1.6 episodes per week and of ICD shock interventions by 81.2% was observed. Besides periprocedural nausea with a single episode of vomiting, no treatment-associated side effects were noted. Unfortunately, the patient died 57 days after CRS/RA due to sepsis-associated cardiac circulatory failure after Clostridium difficile-associated colitis developed during rehabilitation. Histopathologic examination of the heart as part of a clinical autopsy revealed diffuse fibrosis on most sections of the heart without apparent differences between the target area and the posterior cardiac wall serving as a control. CONCLUSION: CRS/RA appears to be a possible treatment option for otherwise untreatable patients suffering from refractory VT and electrical storm. A relevant reduction in VT incidence and ICD interventions was observed, although long-term outcome and consequences of CRS/RA remain unclear. Clinical trials are strongly warranted and have been initiated.

Congenitally corrected transposition of the great arteries: is it really a transposition? An anatomical study of the right ventricular septal surface.

Congenitally corrected transposition of the great arteries (ccTGA) is a rare congenital malformation which associates discordant atrioventricular and ventriculo-arterial connections. Although frequently associated with a ventricular septal defect (VSD), its anatomy remains controversial. This could be due in hearts with usual atrial arrangement to the apparently different anatomy of the left-sided right ventricle compared with a right-sided right ventricle. We wanted to compare the RV septal anatomy between ccTGA, transposition of the great arteries and normal heart and to determine the anatomy of the VSD in ccTGA. We analysed 102 human heart specimens: 31 ccTGA, 36 transpositions of the great arteries, 35 normal hearts. According to the last classification of VSD (ICD-11), VSD were classified as outlet if located above the superoseptal commissure of the tricuspid valve and inlet if underneath. We measured the lengths of the superior and inferior limbs of the septal band and the angle between the two limbs. To assess the orientation of the septal band, we also measured the angle between superior limb and the arterial valve above. A VSD was present in 26 ccTGA (84%) and was an outlet VSD in 16 cases (61%). The mean angle between the two limbs of the septal band was 76.4° for ccTGA compared with 90.6° for transposition of the great arteries (P = 0.011) and 76.1° for normal hearts (P= NS). The mean angle between the superior limb of the septal band and the arterial valve above was 70.6° for ccTGA compared with 90.6° for transposition of the great arteries (P = 0.0004) and 69.1° for normal hearts (P= NS). The inferior limb of the septal band was significantly shorter in ccTGA (P < 0.0003): SL/IL length ratio was 21.4 for ccTGA, 2.2 for transposition of the great arteries and 1.5 for normal hearts. The typical VSD in ccTGA is an outlet VSD. Its frequent misdiagnosis as an inlet VSD might be explained by the shortness of the inferior limb, which creates the illusion of a posterior VSD, and by the fact that the VSD is usually assessed from the left ventricular aspect. Surprisingly, the orientation of the septal band is similar in ccTGA and normal heart, despite the discordant atrioventricular connections, and different in ccTGA and transposition of the great arteries, despite the discordant ventriculo-arterial connections. These findings suggest that the mechanism leading to transposition in ccTGA and in TGA probably is different. The term 'double discordance' might therefore be more appropriate as a description of this complex anomaly.

Larger infarct size but equal protection by ischemic conditioning in septum and anterior free wall of pigs with LAD occlusion.

The ischemic area at risk (AAR) is one major determinant of infarct size (IS). In patients, the largest AAR is seen with a proximal occlusion of the left anterior descending (LAD) coronary artery, which serves parts of the septum and of the anterior free wall. It is not clear, whether regional differences in the perfusion territories also impact on IS and the magnitude of cardioprotection by ischemic conditioning. We have retrospectively analyzed 132 experiments in pigs, which have a similar LAD perfusion territory as humans. The LAD was occluded for 60 min with subsequent 180 min reperfusion. Cardioprotection by either local ischemic pre- or postconditioning or remote ischemic pre- or perconditioning was induced in 93 pigs. The AAR was demarcated by blue dye staining, and IS was assessed by triphenyltetrazolium chloride (TTC) staining. Using digital planimetry, the AAR was separated into sections unequivocally located in the septum (AARS ) or the anterior free wall (AARAFW ). Relative IS was calculated for AARS or AARAFW . AARAFW was larger than AARS (51 ± 9% vs. 34 ± 8% of total AAR; mean ± SD, P < 0.001). Regional myocardial blood flow (microspheres) was not different between septum and anterior free wall. IS without ischemic conditioning tended to be larger in AARS than in AARAFW (50 ± 17% vs. 44 ± 19%; % of AARAWF or AARS , respectively; P = 0.075). Also, with robust IS reduction by ischemic conditioning, the difference in relative IS remained (AARS : 27 ± 16%; AARAFW : 21 ± 16%; P = 0.01). There is a somewhat greater susceptibility for infarction in septal than anterior free wall myocardium. However, ischemic conditioning still reduces IS in both septal and anterior free wall myocardium.