Ventricular Outflow Tract Obstruction Research Articles

Hypertrophic Cardiomyopathy as a Form of Heart Failure with Preserved Ejection Fraction: Diagnosis, Drugs, and Procedures.

Hypertrophic cardiomyopathy (HCM) is a complex and heterogeneous cardiac disorder characterized by cardiac hypertrophy disproportionate to loading stimuli (e.g. hypertension or aortic stenosis). Diagnosing HCM requires a thorough examination of clinical symptoms, with echocardiography as the key initial imaging tool. Multimodality imaging further supports diagnosis, helps assess left ventricular outflow obstruction, and aids in risk stratification for sudden cardiac death. The cornerstone of HCM management remains pharmacological therapy with β-blockers and calcium channel blockers serving as first-line agents to alleviate symptoms and reduce left ventricular outflow tract obstruction. More recently, cardiac myosin inhibitors have revolutionized the treatment paradigm for obstructive HCM. Procedural interventions such as septal reduction therapy are reserved for refractory cases. Genetic testing and risk stratification for sudden cardiac death play a critical role in treatment decisions, guiding further testing in first-degree relatives and ICD implantation in high-risk individuals. Exercise recommendations have evolved based on recent data, challenging traditional restrictions and emphasizing individualized plans.

Post myocardial infarction left ventricular intramyocardial dissecting hematoma penetrated right ventricular outflow tract: a rare complication report

BackgroundIntramyocardial dissecting hematoma (IDH) is a rare mechanical complication following myocardial infarction (MI), and only a few isolated cases have been reported to date. IDH presents with diverse clinical manifestations, often resulting in missed or misdiagnosed cases due to limited physician understanding. The diagnosis and treatment of IDH is a major challenge.Case presentationsWe report a case of acute extensive anterior MI in a 73-year-old woman, who underwent percutaneous coronary intervention (PCI); the left ventricular intramyocardial dissecting hematoma (LVIDH) penetrated the right ventricular outflow tract (RVOT), resulting in thrombus formation and subsequent RVOT obstruction. Clinically insignificant IDH was detected by transthoracic echocardiography (TTE) at 3 days, 43 days, and 75 days post-PCI, with characteristic changes in the left ventricular wall ultrasound images. This unusual case highlights the important role of continuous transthoracic echocardiography in identifying this rare complication of LVIDH. After a detailed discussion with the patient, the choice between conservative or surgical management of IDH depends on factors such as the size of the hematomae, left ventricular systolic function, and the patient’s clinical and haemodynamic status. In this particular case, conservative management was chosen by the patient who declined surgery but unfortunately succumbed to cardiogenic shock.ConclusionsThis case describes a rare complication of acute myocardial infarction (AMI) and also focuses on the utility of TTE in the diagnosis of this rare complication. Whether LVIDH is treated conservatively or surgically requires careful evaluation to achieve the best prognosis for the patient.

Real-world experience in initiation of treatment with the selective cardiomyosin inhibitor mavacamten in an outpatient clinic cohort during the 12-week titration period.

Lately, mavacamten emerged as a new therapeutic option for symptomatic patients with obstructive hypertrophic cardiomyopathy (oHCM). Clinical trials revealed reduction of serum biomarkers, and left ventricular outflow tract (LVOT) obstruction, as well as an improvement in clinical symptoms and exercise capacity. Nevertheless, clinical experience and manageability of patients in a real-world setting is still lacking. 22 patients with symptomatic oHCM (54.5% male, age 58.5 ± 16.2years) and elevated LVOT gradients were started on mavacamten between March 2023 and June 2024. All patients were New York Heart Association (NYHA) class II or higher. Seven patients were excluded from primary analysis due to comedication with Angiotensin-converting-enzyme-inhibitors or Angiotensin-II receptor blockers. Cardiac imaging, laboratory work-up and clinical evaluation were assessed at three visits during the 12weeks initiation phase; Dosing of mavacamten was adjusted according to manufacturer's recommendations. At 12weeks, the majority of patients described a significant improvement of their quality of life. Work-up at 12weeks revealed a significant reduction of serum biomarkers and LVOT gradients. In four patients, mavacamten needed to be temporarily paused due to clinical complaints or transient left ventricular ejection fraction deterioration below 50% with subsequent full recovery. We provide first insights into the usage of mavacamten in oHCM patients during the titration period in a real-world setting. Clinical findings are in line with previous clinical trials. In accordance with current recommendations, we highlight the need for standardized follow-up of patients on mavacamten treatment.

Clinical Outcomes of Concomitant Secondary Chordal Cutting to Surgical Myectomy in HOCM.

In patients who underwent surgical septal myectomy for hypertrophic obstructive cardiomyopathy (HOCM), additional mitral valve repair may offer additional benefits in terms of further reducing left ventricle outflow tract (LVOT) gradients, systolic anterior motion (SAM) and mitral regurgitation (MR). We performed a systematic review of the literature to evaluate the evidence of surgical myectomy with additional secondary chordal cutting in patients with HOCM. A systematic literature search in MEDLINE and EMBASE was performed until April 2024. The primary outcome studied was postoperative echocardiographic LVOT-gradient. A random effects meta-analysis of means was performed for the primary outcome. The secondary outcomes studied were postoperative residual MR-grade, 30-day new permanent pacemaker implantation, and in-hospital mortality. From 1911 unique publications, a total of 6 articles fulfilled the inclusion criteria and comprised 471 patients with a pooled mean preoperative resting LVOT gradient of 84 mmHg (95% CI: 76-91). The postoperative pooled mean LVOT-gradient was 11 mmHg (95% CI: 10 - 12) with a low heterogeneity (I2 = 44%). The residual LVOT gradient exceeding 30 mmHg was present in 9 (1%) patients. MR-grade 3 or 4 at hospital discharge was present in 7 (1%) patients. The 30-day new permanent pacemaker implantation rate was 7% and the in-hospital mortality was 0.4%. This systematic review and meta-analysis demonstrate that combining surgical septal myectomy with secondary chordal cutting can be performed safely and effectively eliminate LVOT obstruction in HOCM patients. Further studies are needed to determine the additive effectiveness of additional secondary chordal cuttings.

Complete atrioventricular block after atrial flow regulator implantation in a 5 kg infant.

The atrial flow regulator is a new self-expandable double-disc fenestrated device providing a calibrated inter-atrial communication. Paediatric reports are scarce. We herein describe a case of complete atrioventricular block complicating the exemption use of an atrial flow regulator in a 5-kg infant with transposition of the great arteries, ventricular septal defect, and right ventricular outflow tract obstruction.

Long-Term Outcomes After Septal Reduction Therapies in Obstructive Hypertrophic Cardiomyopathy: Insights From the SHARE Registry.

Septal reduction therapy (SRT) provides substantial symptomatic improvement in patients with obstructive hypertrophic cardiomyopathy (HCM). However, long-term disease course after SRT and predictors of adverse outcomes have not been systematically examined. Data from 13 high clinical volume HCM centers from the international SHARE (Sarcomeric Human Cardiomyopathy Registry) were analyzed. Patients were followed from the time of SRT until last follow-up or occurrence of heart failure (HF) composite outcome (cardiac transplantation, implantation of a left ventricular assist device, left ventricular ejection fraction <35%, development of New York Heart Association class III or IV symptoms), ventricular arrhythmias composite outcome (sudden cardiac death, resuscitated cardiac arrest, or appropriate implantable cardioverter defibrillator therapy), or HCM-related death. Cox proportional hazards models were used to identify predictors of outcome. Of the 10 225 patients in SHARE, 1832 (18%; 968 [53%] male) underwent SRT, including 455 (25%) with alcohol septal ablation and 1377 (75%) with septal myectomy. The periprocedural 30-day mortality rate was 0.4% (8 of 1832) and 1499 of 1565 (92%) had a maximal left ventricular outflow tract gradient <50 mm Hg at 1 year. After 6.8 years (range, 3.4-9.8 years; 12 565 person-years) from SRT, 77 (4%) experienced HCM-related death (0.6% per year), 236 (13%) a composite HF outcome (1.9% per year), and 87 (5%) a composite ventricular arrhythmia outcome (0.7% per year). Among adults, older age at SRT was associated with a higher incidence of HCM death (hazard ratio, 1.22 [95 CI, 1.1-1.3]; P<0.01) and the HF composite (hazard ratio, 1.14 [95 CI, 1.1-1.2] per 5-year increase; P<0.01) in a multivariable model. Female patients also had a higher risk of the HF composite after SRT (hazard ratio, 1.4 [95 CI, 1.1-1.8]; P<0.01). De novo atrial fibrillation occurred after SRT in 387 patients (21%). Among pediatric patients followed for a median of 13 years after SRT, 26 of 343 (16%) developed the HF composite outcome, despite 96% being free of recurrent left ventricular outflow tract obstruction. Successful short- and long-term relief of outflow tract obstruction was observed in experienced multidisciplinary HCM centers. A subset of patients progressed to develop HF, but event-free survival at 10 years was 83% and ventricular arrhythmias were rare. Older age, female sex, and SRT during childhood were associated with a greater risk of developing HF.

Commentary: The more the merrier. Another technique to treat left ventricular outflow tract obstruction.

Commentary: The more the merrier. Another technique to treat left ventricular outflow tract obstruction.

TCT-476 Alcohol Septal Ablation Prior to Transcatheter Aortic Valve Replacement in Patients With Concomitant Left Ventricular Outflow Tract Obstruction and Aortic Stenosis

TCT-476 Alcohol Septal Ablation Prior to Transcatheter Aortic Valve Replacement in Patients With Concomitant Left Ventricular Outflow Tract Obstruction and Aortic Stenosis

Direct Implantation of Transcatheter Valve in Mitral Annular Calcification: A Multi-Center Study

BACKGROUNDMitral valve replacement (MVR) in the setting of severe annular calcification (MAC) is associated with high morbidity and mortality. Direct surgical implantation of a transcatheter heart valve (THV) through a trans-atrial approach is a strategy to mitigate surgical risk. This study reports the peri-operative and 1-year outcomes of MVR using a THV in patients with severe circumferential MAC at three Canadian centers. METHODSCharts were reviewed between 1/1/2018 and 30/9/2023 to identify patients with severe circumferential MAC who had undergone direct implantation of a THV. Primary outcomes were 30-day mortality, debilitating stroke, and 1-year mortality. Secondary outcomes included left ventricular outflow tract obstruction (LVOTO), degree of PVL, transvalvular mean pressure gradient, and length of stay. RESULTSTwenty-two patients at the three centres underwent direct implantation of a THV. Nineteen were female with mean age 70.41±9.33 years. A THV was successfully implanted in all patients. There were two deaths at 30-days. Four died from non-cardiac causes at 1-year, and 1 patient had a post-operative stroke. Seventeen (77%) patients had none/trace paravalvular leak, 4 had mild PVL, and one patient had mild-moderate PVL. Mean trans-valvular gradient was 4.42±4.40. There were no cases of LVOTO. CONCLUSIONSDirect deployment of a THV in patients with severe MAC may be a reasonable option. Thirty-day and 1-year mortality rates of 9% and 18%, respectively, suggest that this approach should be reserved for high-risk patients who are not able to undergo conventional strategies.

Burden of reintervention after tetralogy of Fallot repair: A joint pediatric and adult congenital experience over 30 years

ObjectiveThere is a high burden of reintervention after repair of tetralogy of Fallot (TOF). We compare procedural burden and late outcomes in valve-sparing repair (VSR) and transannular patch (TAP) cohorts over 30 years. MethodsPatients undergoing TOF repair (1990-2021, excluding complex TOF) were included in this study (n = 1239) with subsequent comparisons between TAP (n = 550) and VSR (n = 648) cohorts. Descriptive statistics, cumulative incidence frequencies, survival analysis, and propensity matching (n = 425) were used to analyze reintervention burden and survival. ResultsOverall survival of the cohort was 96.7% at 15 years and 95.6% at 25 years, with similar survival between TAP and VSR cohorts (P = .22). The TAP cohort had increased incidence of procedural burden at 25 years (TAP 69.8% vs VSR 37.2%; P < .001), with 34.6% undergoing ≥2 reinterventions. The TAP cohort had higher incidence of surgical pulmonary valve replacement at 15 years (TAP 20.7% vs VSR 7.6%; P < .001) and placement of pulmonary artery stents (TAP 20.2% vs VSR 4.9%; P < .001). By contrast, VSR had higher incidence of right ventricular outflow tract (RVOT) reoperation at 15 years (VSR 7.3% vs TAP 3.6%; P = .047). After propensity score matching there was no survival advantage between the VSR and TAP cohorts (Era 2), whereas the need for RVOT reoperation was not different between the 2 cohorts (P = .060). ConclusionsThe procedural burden remains high following TOF repair. TAP is associated with higher procedural burden in matched and nonmatched cohorts. VSR has increased risk of reoperation for RVOT obstruction only in nonmatched comparisons. Anatomical complexity and surgical repair strategy influence procedural burden following TOF repair.

Evaluation of potential links between phenotypic features and genetic variants in left ventricular outflow tract obstruction in hypertrophic cardiomyopathy using cardiovascular magnetic resonance imaging.

This study aimed to identify the phenotypic features contributing to the development of left ventricular outflow tract obstruction (LVOTO) in patients with hypertrophic cardiomyopathy (HCM) and to evaluate the genotype‒phenotype relationship. This cross-sectional study included 96 patients diagnosed with HCM (mean age: 56.9 ± 13.5 years, 32.3% female). The patients were divided into hypertrophic nonobstructive cardiomyopathy (HNCM; n = 60) and hypertrophic obstructive cardiomyopathy (HOCM; n = 36) groups. All patients underwent CMR. Patients (n = 77) who had previously provided formal approval underwent a genetic examination that included 18 genes. The anterior mitral leaflet (AML) length/LVOT diameter ratio, posterior mitral leaflet (PML) length/LVOT diameter ratio, and anterolateral papillary muscle (AL-PM) mobility were associated with LVOTO, independent of the basal IVS thickness, abnormal chordal attachment, and bifid PM. An AML length/LVOT diameter ratio of ≥ 2.30, a PML length/LVOT diameter ratio of ≥ 1.83, and an AL-PM mobility of ≥ 57.7% were predictors of LVOTO, with good sensitivity and specificity. Positive variants (VUS, LP, and P) were detected in 37.7% (29 of 77) of the patients who underwent genetic testing. The LP/P variant was detected in 20.8% (16 of 77) of patients. Three groups (variant-negative, VUS, and LP/P groups) had significant differences in the LVOT diameter (median 14, 12, and 10mm, respectively; p = 0.021), AML length (mean 25.3, 26.5, and 27.5mm, respectively; p = 0.029), AML length/LVOT diameter ratio (median 1.74, 2.33, and 2.85, respectively; p = 0.006), PML length/LVOT diameter ratio (median 1.29, 1.82, and 2.10, respectively; p = 0.045), and abnormal chordal attachment (6.3%, not observed, and 31.3%, respectively; p = 0.009). The AML length/LVOT diameter ratio, PML length/LVOT diameter ratio, and AL-PM mobility were associated with LVOTO. In addition, genetic testing results may provide information regarding the phenotypic expression of patients with HCM.

Modulating energy metabolism to treat non-obstructive hypertrophic cardiomyopathy? Insights from IMPROVE-HCM.

Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disease worldwide and may present with or without dynamic left ventricular outflow tract obstruction (LVOTO). Significant advances have been made in the management of obstructive HCM. On the other hand, despite their significant symptomatic burden, patients with non-obstructive HCM (nHCM) (i.e., without LVOTO) still do not have evidence-based therapeutical options. The recent IMPROVE-HCM study, a phase 2 randomized, double-blinded trial, aims to place a first step in filling this gap in knowledge. The study assessed the safety (primary endpoint) and efficacy (secondary endpoint) of ninerafaxstat, a novel cardiac mitotrope drug that increases adenosine triphosphate production. We highlighted the main findings of the trial, contextualizing these results within the larger landscape of completed and ongoing trials in nHCM.

How effective is disopyramide in treating pediatric hypertrophic cardiomyopathy? State of the art and future directions.

Pediatric hypertrophic cardiomyopathy (HCM) has a wide range of clinical manifestations. Left ventricular outflow tract obstruction (LVOTO) at rest is present in up to one-third of children with HCM, with a further 50-60% of symptomatic children developing a gradient under exertion. Treatment options are limited, and there is a relative lack of data on the pediatric population. Disopyramide is a sodium channel blocker with negative inotropic properties. This therapy effectively reduces LVOTO in adults with HCM and delays surgical interventions, but it is not licensed for use in children. We aimed to review and analyze the influence of disopyramide over the pathophysiological, clinical, electrocardiographic, and echocardiographic characteristics of patients with HCM in infancy, childhood, adolescence, and adult age. While disopyramide remains a cornerstone in the management of pediatric HCM, the advent of mavacamten and aficamten heralds a new era of potential advancements. These emerging therapies could significantly improve the quality of life and prognosis for young patients with HCM.

Silent Threats of the Heart: A Case Series and Narrative Review on Suicide Left Ventricle Post-Aortic Valve Replacement in Patients with Dynamic LVOT Obstruction and Aortic Stenosis.

Aortic stenosis (AS) is the most prevalent valvular heart disease in Europe and North America, with transcatheter aortic valve implantation (TAVI) revolutionizing its management. Hypertrophic left ventricle (HLV) frequently coexists with AS, complicating treatment due to the associated risk of left ventricular outflow tract (LVOT) obstruction, heart failure, and sudden death. A rare but severe post-aortic valve replacement (AVR) complication, termed "suicide left ventricle" (SLV), has emerged, necessitating further study. This report synthesizes current literature on SLV, its pathophysiology, and management strategies, alongside four patient case studies. The patients aged 79-87 years, underwent AVR for symptomatic AS with HLV. Post-AVR, all experienced severe complications, including dynamicLVOT gradients, systolic anterior motion (SAM) of the mitral valve, and severe hypotension, leading to death in two cases. One patient survived following surgical aortic valve replacement (SAVR) with surgical myectomy. One patient survived after TAVI. These cases highlight the critical importance of multidisciplinary Heart Team evaluations and personalized treatment plans in managing SLV. Despite advancements in AVR, SLV remains a complex, life-threatening condition, requiring an exhaustive and multifaceted approach for optimal patient outcomes. This report offers valuable insights into SLV occurrence and management from a clinical perspective.

Takotsubo syndrome with transient obstruction of the left ventricle outflow tract: A case report

BACKGROUND: Modern data have expanded our understanding of the pathogenetic mechanisms and clinical and laboratory findings in a patient with Takotsubo syndrome (TS). Nonetheless, its timely diagnosis and treatment remain challenging. All patients are initially treated according to the acute coronary syndrome protocol, with a "working" diagnosis of myocardial infarction without an obstructive lesion in the coronary arteries. However, the treatment of in-hospital complications of TS has its limitations and specific features. CLINICAL CASE DESCRIPTION: Herein, we have reported a case of TS that presented with the classic apical ballooning of the left ventricular apex, which had developed without an obvious stress factor, which is quite rare. The disease was complicated by the development of cardiogenic shock (CGS) and transient obstruction of the left ventricular outflow tract (LVOTO), which reportedly occurs in about 25% of the patients. CGS in patients with TS is a life-threatening complication and a challenging therapeutic problem, especially when it is also associated with a dynamic LVOTO. In such conditions, the only therapeutic option is mechanical circulatory support. However, in our patient, low doses of dobutamine were used to stabilize the patient’s hemodynamics. This treated produced a good therapeutic effect. CONCLUSION: Our case report findings emphasize the need for further research into the mechanisms of LVOTO development in TS, as well as the development of standardized approaches for the treatment of such patients in the acute phase of the disease.

Impact and limitations of 3D computational modelling in transcatheter mitral valve replacement-atwo-centre Dutch experience.

Transcatheter mitral valve replacement (TMVR) has emerged as aminimally invasive alternative to mitral valve surgery for patients at high or prohibitive operative risk. Prospective studies reported favourable outcomes in patients with annulus calcification (valve-in-mitral annulus calcification; ViMAC), failed annuloplasty ring (mitral valve-in-ring; MViR), and bioprosthetic mitral valve dysfunction (mitral valve-in-valve; MViV). Multi-slice computed tomography (MSCT)-derived 3D-modelling and simulations may provide complementary anatomical perspectives for TMVR planning. We aimed to illustrate the implementation of MSCT-derived modelling and simulations in the workup of TMVR for ViMAC, MViR, and MViV. For this retrospective study, we included all consecutive patients screened for TMVR and compared MSCT data, echocardiographic outcomes and clinical outcomes. Sixteen out of 41patients were treated with TMVR (ViMAC n = 9, MViR n = 3, MViV n = 4). Eleven patients were excluded for inappropriate sizing, 4for anchoring issues and 10for an unacceptable risk of left ventricular outflow tract obstruction (LVOTO) based on 3D modelling. There were 3procedure-related deaths and 1non-procedure-related cardiovascular death during 30days of follow-up. LVOTO occurred in 3ViMAC patients and 1MViR patient, due to deeper valve implantation than planned in 3patients, and anterior mitral leaflet displacement with recurrent basal septum thickening in 1patient. TMVR significantly reduced mitral mean gradients as compared with baseline measurements (median mean gradient 9.5(9.0-11.5) mm Hg before TMVR versus 5.0(4.5-6.0) mm Hg after TMVR, p = 0.03). There was no residual mitral regurgitation at 30days. MSCT-derived 3D modelling and simulation provide valuable anatomical insights for TMVR with transcatheter balloon expandable valves in ViMAC, MViR and MViV. Further planning iterations should target the persistent risk for neo-LVOTO.

Pathogenesis and Surgical Treatment of Congenitally Corrected Transposition of the Great Arteries (ccTGA): Part III.

Congenitally corrected transposition of the great arteries (ccTGA) is an infrequent and complex congenital malformation, which accounts for approximately 0.5% of all congenital heart defects. This defect is characterized by both atrioventricular and ventriculoarterial discordance, with the right atrium connected to the morphological left ventricle (LV), ejecting blood into the pulmonary artery, while the left atrium is connected to the morphological right ventricle (RV), ejecting blood into the aorta. Due to this double discordance, the blood flow is physiologically normal. Most patients have coexisting cardiac abnormalities that require further treatment. Untreated natural course is often associated with progressive failure of the systemic right ventricle (RV), tricuspid valve (TV) regurgitation, arrhythmia, and sudden cardiac death, which occurs in approximately 50% of patients below the age of 40. Some patients do not require surgical intervention, but most undergo physiological repair leaving the right ventricle in the systemic position, anatomical surgery which restores the left ventricle as the systemic ventricle, or univentricular palliation. Various types of anatomic repair have been proposed for the correction of double discordance. They combine an atrial switch (Senning or Mustard procedure) with either an arterial switch operation (ASO) as a double-switch operation or, in the cases of relevant left ventricular outflow tract obstruction (LVOTO) and ventricular septal defect (VSD), intra-ventricular rerouting by a Rastelli procedure. More recently implemented procedures, variations of aortic root translocations such as the Nikaidoh or the half-turned truncal switch/en bloc rotation, improve left ventricular outflow tract (LVOT) geometry and supposedly prevent the recurrence of LVOTO. Anatomic repair for congenitally corrected ccTGA has been shown to enable patients to survive into adulthood.

Microcatheter-Facilitated Alcohol Septal Ablation For Residual Left Ventricular Outflow Tract Obstruction

Microcatheter-Facilitated Alcohol Septal Ablation For Residual Left Ventricular Outflow Tract Obstruction

A Rare Case of Ebstein’s Anomaly with Biventricular Noncompaction

Abstract Ebstein’s anomaly is a rare cyanotic congenital heart disease, which can present with right heart failure when associated with septal defects and/or right ventricular outflow tract obstruction. Left ventricular failure is extremely rare, and we report one such case due to the coexistence of biventricular noncompaction.

2023 ESC guidelines for management of cardiomyopathies: short review with implications for the clinical practice in Bulgaria

The 2023 European Society of Cardiology guidelines for the management of cardiomyopathies (CM) provide practical recommendations for diagnosis and treatment. They emphasize on the need for a systematic clinical evaluation beginning with clinical suspicion of CM and using a multiparametric approach that leads to classification of CM into one of five distinct phenotypes. &amp;#1040; cardiomyopathy mindset, together with a multidisciplinary approach are crucial. Further investigations, including advanced imaging and genetic testing, are needed to make a phenotype-based etiological diagnosis. Detection of pathogenic genetic variants allows risk stratification of sudden cardiac death, where new recommendations are available regarding primary prevention. Therapeutic options are expanded with the approval of a new class of drugs for the treatment of symptomatic hypertrophic cardiomyopathy with left ventricular outflow tract obstruction. Specific exercise recommendations are given and reproductive issues in patients with CM are addressed. The lack of reimbursement by the National Health Insurance Fund (NHIF) of genetic testing and the severely limited reimbursement of some imaging methods are a significant problem in Bulgaria, which leads to difficulties in implementing the new guidelines.