Left ventricular ejection hemodynamics before and after relief of outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy and valvular aortic stenosis

Treatment Strategies for Hypertrophic Cardiomyopathy: Surgical

Septal myectomy is a well-established procedure for septal reduction in patients with obstructive hypertrophic cardiomyopathy (HCM) who have not responded to medical treatment. The surgical approach is tailored to the unique pathophysiology and septal morphology of the patient. Extended transaortic myectomy is the standard procedure for patients with isolated subaortic obstruction, the most common type of HCM. However, transapical myectomy is a useful adjunct for patients with long or midventricular obstruction and is our preferred technique for ventricular enlargement in patients with severe symptomatic diastolic heart failure because of extensive apical hypertrophy. Septal myectomy provides excellent postoperative outcomes as regards symptom relief and functional improvement, and operative morbidity and mortality rates are low in experienced centers. This article summarizes our current surgical management of patients with HCM and details operative methods and outcomes.

Contemporary Surgical Management of Hypertrophic Cardiomyopathy

More than half of symptomatic patients with hypertrophic cardiomyopathy (HCM) have left ventricular outflow tract (LVOT) obstruction. Septal reduction therapy by septal myectomy can dramatically relieve exertional dyspnea, chest pain, and presyncope in properly selected patients and is an important management pathway for many patients. The distribution and degree of hypertrophy in patients with obstructive HCM are variable and, as discussed in this review, can influence clinical manifestations of the disease and surgical management. Subaortic septal hypertrophy is the most common phenotype of obstructive HCM associated with LVOT obstruction, but midventricular obstruction and apical hypertrophy may occur in isolation or in conjunction with subaortic septal hypertrophy. In many comprehensive HCM centers, transaortic septal myectomy is the preferred method of septal reduction therapy for symptomatic patients with obstructive HCM. Early surgical approaches aimed at alleviating left LVOT obstruction were hampered by a lack of understanding of the anatomy and pathophysiology of obstructive HCM. With the advent of Doppler echocardiography and, more recently, cardiac magnetic resonance imaging, surgeons can precisely assess the location and degree of obstruction, left ventricular size and function, and morphology and function of the mitral valve. This review discusses the current understanding of the role of septal myectomy in the management of patients with HCM and details contemporary operative methods.

Cardiopulmonary exercise test in patients with obstructive hypertrophic cardiomyopathy

OBJECTIVE

The study objective was to analyze performance on cardiopulmonary exercise testing and its prognostic value in patients with obstructive hypertrophic cardiomyopathy undergoing septal myectomy.

METHODS

We reviewed patients with obstructive hypertrophic cardiomyopathy who had cardiopulmonary exercise testing before septal myectomy from 2005 to 2016. Causes of functional impairment and their impact on survival were analyzed.

RESULTS

A total of 752 patients had cardiopulmonary exercise testing at a median of 16 days (interquartile range, 2-56) before myectomy. The median exercise time was 6.6 (5.3-8.0) minutes. Functional aerobic capacity was 64% (53%-75%) of predicted, and metabolic equivalent of task was 5.2 (4.1-6.4). The peak oxygen consumption was 18.0 (14.2-21.9) mL/kg/min, which was 60% (49%-72%) of the predicted value. The primary causes for low peak oxygen consumption were impaired cardiac output (73.7%), limited heart rate reserve (52.0%), and obesity (48.2%). Resting outflow tract gradient correlated poorly to peak oxygen consumption, but the use of beta-blockers was associated with reduced peak oxygen consumption. During a median (interquartile range) of 9.0 (6.8-11.7) years of follow-up, the estimated 5- and 10-year survivals were 97% and 91%, respectively. Greater adjusted peak oxygen consumption (hazard ratio, 0.98; P = .011) and abnormal pulse oxygen increase (hazard ratio, 0.44; P = .003) were independently associated with better long-term survival after myectomy.

CONCLUSIONS

Among patients with hypertrophic cardiomyopathy undergoing septal myectomy, functional capacity is severely impaired despite receiving optimal medical treatment. We identified risk factors of reduced long-term survival from preoperative cardiopulmonary exercise testing that may aid risk stratification in patients undergoing septal myectomy.

Hemodynamic Predictors of Outcome Following Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy

BACKGROUND

Alcohol septal ablation (ASA) is a minimally invasive treatment for drug-refractory obstructive hypertrophic cardiomyopathy. Detailed assessment of pressure changes and predictors of mortality and procedure success are not well defined.

METHODS

This is a single-center study evaluating pressure changes and predictors of mortality and procedure success in transseptal ASA. Survival analysis and predictors of mortality were assessed using the Kaplan-Meier analysis and Cox regression, respectively.

RESULTS

A total of 156 patients were included (mean age, 67.3 years; 46.8% women). Left atrial (LA) pressure and left ventricular outflow tract (LVOT) gradient decreased, whereas aortic pulse pressure (PP) increased post-ASA. Patients with lower baseline mean LA pressure (82% (gradient change median), and PP increase >19% (PP change median) had superior survival. On Cox univariable regression, baseline mean LA pressure >median (19 mm Hg; hazard ratio [HR], 2.09 [95% CI, 1.05-4.18]; P=0.036), residual LVOT gradient (HR, 1.02 [95% CI, 1.01-1.03]; P=0.003), and LVOT gradient percent reduction median (28 mm Hg; HR, 2.36 [95% CI, 1.17-4.76]; P=0.016), baseline mean LA pressure >median (19 mm Hg; HR, 2.70 [95% CI, 1.33-5.50]; P=0.006), percentage reduction in gradient

CONCLUSIONS

ASA is associated with an acute decrease in the LVOT gradient and LA pressures and increase in aortic PP. Mean LA pressure, percentage decrease in LVOT gradient, and increase in PP are strong predictors of survival free of all-cause mortality following ASA and are important variables for procedural guidance.

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Key Words

• cardiomyopathy, hypertrophic
• heart atria
• hemodynamics

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MESH Headings

• Humans
• Female
• Aged
• Male
• Treatment Outcome
• Ethanol/adverse effects
• Cardiomyopathy, Hypertrophic/diagnostic imaging
• Cardiomyopathy, Hypertrophic/surgery
• Cardiac Surgical Procedures
• Hemodynamics
• Ablation Techniques/adverse effects

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Affiliation(s)

Mohamad S. Alabdaljabar Departments of Internal Medicine (M.S.A.), Mayo Clinic, Rochester, MN
Emily E. Cendrowski Cardiovascular Medicine (E.E.C., R.A.N., W.R.M., J.B.G., C.S.R., M.F.E.), Mayo Clinic, Rochester, MN
Rick A. Nishimura Cardiovascular Medicine (E.E.C., R.A.N., W.R.M., J.B.G., C.S.R., M.F.E.), Mayo Clinic, Rochester, MN
William R. Miranda Cardiovascular Medicine (E.E.C., R.A.N., W.R.M., J.B.G., C.S.R., M.F.E.), Mayo Clinic, Rochester, MN
Jeffrey B. Geske Cardiovascular Medicine (E.E.C., R.A.N., W.R.M., J.B.G., C.S.R., M.F.E.), Mayo Clinic, Rochester, MN
Charanjit S. Rihal Cardiovascular Medicine (E.E.C., R.A.N., W.R.M., J.B.G., C.S.R., M.F.E.), Mayo Clinic, Rochester, MN
Mackram F. Eleid Cardiovascular Medicine (E.E.C., R.A.N., W.R.M., J.B.G., C.S.R., M.F.E.), Mayo Clinic, Rochester, MN

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How to build a successful hypertrophic cardiomyopathy team and ensure training the next generation of myectomy surgeons

Transaortic extended septal myectomy is the most reliable method for septal reduction for symptomatic patients with obstructive hypertrophic cardiomyopathy. In addition, surgical management of nonobstructive hypertrophic cardiomyopathy is possible for selected patients with diastolic heart failure and small left ventricular end-diastolic cavity dimensions. These procedures, however, are performed infrequently in many centers, and trainees may not be exposed to the preoperative evaluation and intraoperative management of patients with hypertrophic cardiomyopathy. In this paper, we review what we believe are the central features for creating a successful program for septal myectomy and detail our strategies to optimize instruction in these techniques for residents and fellows.

Preoperative left ventricular longitudinal strain predicts outcome of septal myectomy for obstructive hypertrophic cardiomyopathy

OBJECTIVE

The objective of this study was to determine the characteristics of longitudinal strain and its effect on outcomes in patients with obstructive hypertrophic cardiomyopathy (HCM) who underwent septal myectomy.

METHODS

We reviewed patients with obstructive HCM who underwent septal myectomy at our clinic from 2007 to 2016. Data of those who had strain echocardiography within 6 months before isolated myectomy were analyzed.

RESULTS

The median age of the 857 patients studied was 55 (interquartile range [IQR], 44-63) years, and 451 (52.6%) were male. Left ventricular ejection fraction was 71% (IQR, 67%-74%), and the resting peak outflow tract gradient was 58 (IQR, 27-85) mm Hg. The median global longitudinal strain (GLS) was -14.6% (IQR, -12.0% to -17.3%). Regional longitudinal strain was nonuniform as reflected by more normal values in apical segments and more abnormal in basal segments. Moreover, GLS correlated poorly with ejection fraction and outflow tract gradient. In 64 patients who had postoperative strain echocardiography, GLS was comparable before and after septal myectomy, but regional strain was more uniform after myectomy. Over a follow-up of 8.3 (IQR, 6.5-10.3) years, when patients were equally stratified according to GLS (cutoff, -14.64%), the group with worse GLS had significantly poorer survival compared with the better GLS group (P = .002). Left ventricular ejection fraction had no association with survival.

CONCLUSIONS

Left ventricular longitudinal strain is nonuniform and might be significantly reduced in patients with obstructive HCM. Septal myectomy does not impair GLS but is associated with more uniform regional strains. Most importantly, reduced GLS preoperatively is strongly and independently associated with increased all-cause mortality after septal myectomy for obstructive HCM.

Outcomes in Patients With Obstructive Hypertrophic Cardiomyopathy and Concomitant Aortic Stenosis Undergoing Surgical Myectomy and Aortic Valve Replacement

Background Hypertrophic cardiomyopathy (HCM) and aortic stenosis can cause obstruction to the flow of blood out of the left ventricular outflow tract into the aorta, with obstructive HCM resulting in dynamic left ventricular outflow tract obstruction and moderate or severe aortic stenosis causing fixed obstruction caused by calcific degeneration. We sought to report the characteristics and longer-term outcomes of patients with severe obstructive HCM who also had concomitant moderate or severe aortic stenosis requiring surgical myectomy and aortic valve replacement. Methods and Results We studied 191 consecutive patients (age 67±6 years, 52% men) who underwent myectomy and aortic valve (AV) replacement (90% bioprosthesis) at our center between June 2002 and June 2018. Clinical and echo data including left ventricular outflow tract gradient and indexed AV area were recorded. The primary outcome was death. Prevalence of hypertension (63%) and hyperlipidemia (75%) were high, with a Society of Thoracic Surgeons score of 5±4, and 70% of participants had no HCM-related sudden death risk factors. Basal septal thickness and indexed AV area were 1.9±0.4 cm and 0.72±0.2 cm²/m², respectively, while 100% of patients had dynamic left ventricular outflow tract gradient >50 mm Hg. At 6.5±4 years, 52 (27%) patients died (1.5% in-hospital deaths). One-, 2-, and 5-year survival in the current study sample was 94%, 91%, and 83%, respectively, similar to an age-sex-matched general US population. On multivariate Cox survival analysis, age (hazard ratio [HR], 1.65; 95% CI, 1.24-2.18), chronic kidney disease (HR, 1.58; 95% CI, 1.21-2.32), and right ventricular systolic pressure on preoperative echocardiography (HR, 1.28; 95% CI, 1.05-1.57) were associated with longer-term mortality, but traditional HCM risk factors did not. Conclusions In symptomatic patients with severely obstructive HCM and moderate or severe aortic stenosis undergoing a combined surgical myectomy and AV replacement at our center, the observed postoperative mortality was significantly lower than the expected mortality, and the longer-term survival was similar to a normal age-sex-matched US population.

Impact of septal myectomy on diastolic function in patients with obstructive hypertrophic cardiomyopathy

Background

The impact of septal myectomy on diastolic function in patients with obstructive hypertrophic cardiomyopathy is not well studied.

Methods

A transcatheter hemodynamic study was performed before and 3 to 6 months after septal myectomy in 12 patients with obstructive hypertrophic cardiomyopathy (HCM).

Results

Postoperative hemodynamic studies were done 4.4±1.2 months after myectomy. The left ventricular outflow tract peak-to-peak gradient decreased from 83.2±43.3 mmHg preoperatively to 11.6±4.3 mmHg after myectomy (P<0.00). The left ventricular diastolic time constant (Tau) was 64.2±26.1 ms before surgery and 42.2±15.7 ms postoperatively (P=0.029). The average left atrial pressure (LAP) decreased from 20.2±7.0 to 12.1±4.5 mmHg after myectomy (P=0.008). Pulmonary artery hypertension was present in 6 patients preoperatively and remained in 2 patients after myectomy. Mean pulmonary artery pressure decreased from 29.3±16.2 to 20±6.7 mmHg after surgery (P=0.05), and the systolic pulmonary artery pressure decreased from 46±26.9 to 30.5±8.3 mmHg (P=0.048). Pulmonary vascular resistance decreased from 5.7±4.1 to 3.6±1.6 wood after surgery (P=0.032).

Conclusions

Septal myectomy improved left ventricular diastolic function and subsequently relieved the right ventricular congestion in patients with obstructive HCM.

Clinical value of 2D speckle tracking imaging in evaluating the effect of percutaneous intramyocardial septal radiofrequency ablation in patients with hypertrophic obstructive cardiomyopathy

PURPOSE

To explore the short-term changes after percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) in patients with hypertrophic obstructive cardiomyopathy (HOCM), using quantitative analysis of two-dimensional speckle tracking imaging (2D-STI).

METHODS

This prospective self-controlled study included 30 HOCM patients treated with PIMSRA. The study for each patient spanned over at least 1 year. Interventricular septal thickness and the left ventricular outflow tract peak pressure gradient (LVOT-PG) were measured through echocardiography, and 2D-STI was used to evaluate the left ventricular (LV) systolic function and synchrony. Cardiac function was assessed using the New York Heart Association's (NYHA) functional classification for cardiac disease, and through the serum levels of cardiac troponin I (cTnI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Biomarkers procollagen type I carboxy-terminal propeptide (PICP) and matrix metalloproteinases-2 (MMP-2) were detected for noninvasive assessment of myocardial fibrosis.

RESULTS

The patients' interventricular septal thickness, LVOT-PG, NYHA class, and plasma PICP and MMP-2 levels at the first month postoperatively were significantly lower than before operation (all P < .05). The 2D-STI quantitative variables of LV systolic function and synchrony improved significantly (all P < .05). They improved further 1 year postoperatively (P < .01 or P < .001). Serum cTnI and NT-proBNP levels increased 1 month postoperatively, but significantly decreased 1 year postoperatively (both P < .05). Pearson or Spearman correlation analysis showed that the improvement of interventricular septal thickness, LVOT-PG, NYHA class, and the levels of cTnI, NT-proBNP, PICP and MMP-2, were in positive correlation with the restoration of LV systolic function and synchrony (P < .01 or P < .001).

CONCLUSION

The changes in 2D-STI quantitative variables related to LV systolic function and synchrony are closely correlated with the improvement of cardiac function in HOCM patients after PIMSRA. These 2D-STI variables can serve for objective, accurate, and noninvasive evaluation of the HOCM treatment.

Effectiveness of a patient-specific 3-dimensional printed model in Septal Myectomy of hypertrophic cardiomyopathy

Objective:

Advanced cardiovascular surgery in structural heart disease require accurate pre-operative evaluation. Most of non-invasive imaging technologies remain limited in two-dimensional and show insufficiency of visualization for procedural planning. The aim of this study was to discuss the value of patient-specific 3-dimensional (3D) printing in treatment of hypertrophic cardiomyopathy (HCM).

Methods:

Patient-specific 3D-printed models were constructed preoperatively in 12 consecutive HOCM patients which come to Beijing Anzhen Hospital for surgical treatment from October 2016 to March 2017. Image files were extracted from multi-slice computed tomography images, 3D models were constructed by the Mimics 19.0 software and generated by Objet350 Connex3 3D printer. The 3D-printed models were made with soft material that can be surgically performed. The modified Morrow myectomy of the model was performed before the operation. Clinical characters and echocardiographic parameters were recorded.

Results:

There was no significant difference in tissue volume between the models and specimens. Preoperative and postoperative echocardiography showed the septal thickness was reduced from 18.8±4.5 mm to 12.7±3.3 mm (p<0.001), the left ventricular outflow tract obstruction was adequately relieved (83.0±27.73 mm Hg to 8.7±6.5 mm Hg, p<0.001), and the SAM disappeared completely after the operation. Cardiac function was improved in all patients (New York Heart Association functional class III to class I/II).

Conclusions:

The proposed optimal 3D-modelled septal myectomy allows intraoperative monitoring of the shape and volume of the myocardium resection to achieve the ‘ideal’ interventricular septum. It eliminates obstruction in the LVOT and SAM, resulting in LV remodeling with an increase in LV end-diastolic volume and diameter at early follow-up.

Numerical Simulation of the Influence of Geometric Configurations on Pressure Difference in the Intraventricular Tunnel

Objective

The geometric configuration of the intraventricular tunnel is related to the re-intervention of left ventricular outflow tract stenosis after double outlet right ventricle (DORV) correction. Hemodynamic simulation was performed in order to study the influence of the geometric configuration of the IVT on the pressure difference.

Methods

CT images of DORV were processed to reconstruct 3D models of left and right ventricular flow chambers and aortic valve orifice, and then the size and relative position of the aortic valve orifice and ventricular septal defect were determined. Twenty five groups of the idealized models were established according to orthogonal test design and computational fluid dynamics method was applied to simulate hemodynamics. Three factors of geometric configuration were considered for the study of their influences on the pressure difference. The first factor is the distance between the ventricular septal defect and the plane of the aortic valve (D_SA), the second factor is the ejection angle of blood from left ventricle flowing into the IVT (A_LT), and the third factor is the turning radius of the IVT (R_TT). SPSS software was employed to perform the orthogonal analysis. Additionally, twelve models with different turning radii were established for hemodynamic analysis, with the turning radii increasing from 0 mm with an interval of 1 mm, so as to study the influence of turning radius on pressure difference of IVT.

Results

The analysis of variance showed that only the change of R_TT had a significant effect on the pressure difference (P = 0 < 0.05), while the change of D_SA and A_LT had no significant effect on the pressure difference (P = 0.459 > 0.05, P = 0.263 > 0.05). The pressure difference decreases with the increase of R_TT. When R_TT reaches 6 mm, the pressure difference gradually remains unchanged with the increase of R_TT, and the rate of change is less than 5%.

Conclusion

R_TT in the IVT is the main factor affecting the pressure difference. A small R_TT will lead to a large pressure difference in the IVT. When R_TT increases to 6 mm, the pressure difference in the IVT remains nearly unchanged. When performing the right ventricular double outlet correction; the turning radius of the IVT should be about 6 mm to ensure relatively small pressure difference.