Abstract
Background
Achondroplasia is the most common short stature skeletal dysplasia, but there are few reports of cardiac surgical intervention in these patients.
Case Summary
We present a case of mitral valve (MV) repair for mitral regurgitation in a patient with achondroplasia. A 55-year-old man with achondroplasia and obstructive sleep apnea presented with acute-onset dyspnea. Echocardiography demonstrated severe mitral regurgitation with a flail posterior leaflet. He underwent uncomplicated MV repair with artificial cords and an annuloplasty.
Discussion
MV repair is feasible and can be straightforward in patients with achondroplasia. We discuss important considerations for future peri- and intraoperative providers of these patients in cardiac surgery.
Key words: achondroplasia, dwarfism, mitral regurgitation, mitral valve prolapse, mitral valve repair
Graphical Abstract
History of Presentation
A 55-year-old man presented to the emergency department with 2 days of chest tightness and shortness of breath. He was in hypoxic respiratory failure on arrival, so he was placed on noninvasive positive pressure ventilation. The patient’s heart rate was 115 beats/min and his blood pressure was 149/59 mm Hg. His weight was 64.5 kg and his height was 1.37 m (5 feet 6 inches). The patient's physical examination was notable for a holosystolic murmur heard best at the apex. Musculoskeletal findings included short stature, rhizomelia, and brachydactyly, but his chest wall and torso were normal appearing. He did not have peripheral edema.
Past Medical History
The patient had a history of achondroplasia, obstructive sleep apnea, arthritis, and anxiety. He also had a transthoracic echocardiogram (TTE) conducted 2 years before presentation that showed mild mitral regurgitation.
Differential Diagnosis
Based on the patient's presentation, possible diagnoses included congestive heart failure exacerbation, acute coronary syndrome, aortic or mitral valve (MV) dysfunction, reactive airway disease, pneumothorax, pulmonary embolism, or pulmonary hypertension. Neuromuscular, toxic, or metabolic causes of shortness of breath were considered but were less likely.
Investigations
Laboratory findings were notable for a high-sensitivity troponin of 25 ng/L (normal: ≤20 ng/L) and a pro–B-type natriuretic peptide level of 1,526 pg/mL (normal: <125 pg/mL). The electrocardiogram showed normal sinus rhythm with inferior T-wave inversions, a nonspecific conduction abnormality, and QT prolongation. A chest x-ray showed cardiomegaly with pulmonary vascular congestion and edema. Computed tomography angiography of the chest showed interstitial thickening, small bilateral pleural effusions and ground glass opacities, and no pulmonary embolism.
The finding of a new murmur on physical examination prompted TTE, which showed an ejection fraction of 70% to 75% and septal flattening. There was prolapse of the midsegment (P2) of the posterior MV leaflet with multiple ruptured chords and a large coaptation gap (0.8 cm) and severe anteriorly directed mitral regurgitation. There was also moderate pulmonary hypertension, with right ventricle systolic pressure estimated at 62 mm Hg.
Management
The patient was admitted to the cardiac critical care unit for diuresis. Cardiac catheterization demonstrated right-dominant coronary circulation, with no significant coronary disease. After initial stabilization and diuresis, the patient was taken to the operating room for MV repair. After induction of general anesthesia, he was intubated with a 7.0-mm endotracheal tube without difficulty using video laryngoscopy with a hyperangulated blade. A right radial arterial line was placed. Median sternotomy was performed. The cardiac and mediastinal anatomy were normal in size and configuration. A standard sternotomy retractor was used. The ascending aorta was cannulated with an 18-F cannula. The right atrium was cannulated in a bicaval fashion with a 24-F cannula in the superior vena cava and a 28-F cannula in the inferior vena cava. The perfusion strategy was standard. The patient's blood volume was calculated using the Nadler and Lemmens-Bernstein-Brodsky formulas, both of which estimated approximately 3.5 L; a weight-based formula calculated a blood volume of 4.5 L. The average blood volume for an adult male is around 5 L. The calculated flow to achieve the standard cardiac index of 2.4 L/min/m2 in this patient was 3.77 L/min. The flows were 4.54 L/min (cardiac index: 2.89 L/min/m2) for the first half the pump run and 4.04 L/min (cardiac index: 2.58 L/min/m2) for the second half. The difference was possibly because of differences in changes in adequacy of venous drainage at different times. The average flow was 4.29 L/min. The patient had a calculated body surface area of 1.5 m2 (vs 1.9 m2 for an average patient).
On evaluation of the MV, there were several ruptured chords in the midsegment of the posterior leaflet (Figure 1). These were trimmed, and the posterior leaflet was resuspended with a total of 3 pairs of expanded polytetrafluorethylene sutures (CV-5, Gore-Tex; WL Gore & Associates). A 34-mm Physio complete semirigid annuloplasty ring (Edwards Lifesciences) was inserted using 2-0 braided nylon sutures. Intraoperative transesophageal echocardiography demonstrated normal left ventricle and right ventricle function, and there was no residual mitral regurgitation (Figures 2 and 3).
Figure 1.
Mitral Valve Flail Segment Prior to Repair
(Left) Intraoperative midesophageal long-axis view transesophageal echocardiogram of the mitral valve showing a flail segment (P2) of the posterior mitral leaflet displaced into the left atrium during systole. (Right) Color Doppler showing severe mitral regurgitation.
Figure 2.
Mitral Valve After Repair, 4-Chamber View
(Left) Intraoperative midesophageal 4-chamber view transesophageal echocardiogram showing mitral valve after repair with annuloplasty ring and artificial cords. (Right) Color Doppler showing no evidence of residual mitral regurgitation.
Figure 3.
Mitral Valve After Repair, Long-Axis View
(Left) Intraoperative midesophageal long-axis view transesophageal echocardiogram showing mitral valve after repair with annuloplasty ring and artificial cords. (Right) Color Doppler showing no evidence of residual mitral regurgitation.
Outcome
The postoperative course was notable for new atrial fibrillation 2 days after surgery, which resolved after treatment with amiodarone and metoprolol. Predismissal TTE on postoperative day 3 showed normal mobility of the anterior leaflet, restricted motion of the posterior leaflet, well-seated annuloplasty ring, and trace mitral regurgitation. The mean diastolic gradient was 3 mm Hg at a heart rate of 79 beats/min. The patient was discharged from the hospital on postoperative day 6 in good condition.
Discussion
Achondroplasia is the most common short stature skeletal dysplasia, affecting approximately 1 in 25,000 persons worldwide.1 In addition to short stature, it is associated with other clinical features including macrocephaly, midfacial retrusion, thoracolumbar kyphosis, and hyperlordosis.2 Adults with achondroplasia have increased mortality risk compared with the general population, with one study finding a cardiovascular disease mortality rate of 2-fold greater than the general population.3 Causes of heart disease in this population have not been well defined, but there is evidence of an increased prevalence of hypertension.4 Furthermore, there are few reports of cardiac interventions, either surgical or percutaneous, in this patient population.5 In this report, we described a case of MV repair in a patient with achondroplasia who presented acutely with symptomatic mitral regurgitation secondary to MV prolapse.
There are few reports of cardiac surgery in achondroplastic dwarfs.5 The sole previously published case report of a surgical MV repair in a patient with achondroplasia was a combined mitral and tricuspid repair that was also uncomplicated.6 It is unclear why there are so few documented cases of cardiac surgery in this population. A contributing factor could be that achondroplastic patients tend to have a shorter lifespan, estimated at about 10 years less than the general population.7 In recent mortality studies, the crude mortality rate has improved while cardiovascular deaths appear to have increased.8 Further study of the nature of cardiovascular disease in these patients is warranted.
When patients with achondroplasia require cardiac surgery for the management of cardiac disease, both the present case and the previously published experience6 demonstrate that heart surgery is typically straightforward. When planning for such a case, surgeons can use preoperative imaging such as computed tomography to both evaluate for possible comorbidities and to assess the size of major thoracic structures. The patient in this case had a normal-sized chest, allowing for the use of typical adult retractors and cannulas. When planning for perfusion on bypass, a patient with achondroplasia may not necessarily require an alternative strategy. However, when calculating blood volume, major equations (Nadler and Lemmens-Bernstein-Brodsky) based on both height and weight are preferred. When using a weight-based equation that did not incorporate height, the calculated blood volume was inaccurate by over 1 L in our case. In some cases of achondroplastic adults who need cardiac surgery, it may be helpful to consult with pediatric cardiac surgery teams who are familiar with treating patients with small stature, as they may be able to advise regarding anatomical considerations or perfusion needs.
Because of the multisystem involvement of achondroplasia, the anesthetic care for patients with this condition who are undergoing cardiac surgery can be complex, based on characteristic anatomical and pathophysiologic characteristics. This patient population may have spinal or craniofacial abnormalities that necessitate the use of video laryngoscopy or fiberoptic intubation.9 Many patients with achondroplasia have obstructive sleep apnea or central sleep apnea associated with anatomical abnormalities.10 Their chances of developing pulmonary hypertension secondary to these pathologies is increased.9 Obtaining accurate blood pressure monitoring, both invasive and noninvasive, in patients with achondroplasia requires careful attention. A standard blood pressure cuff does not always fit the proximal humerus well in these patients owing to rhizomelia (shortening of proximal limbs) and elbow contracture. Using the forearm instead is recommended. If available, more accurate measurements may be obtained by using a cuff that has a longer length and shorter width.4 For invasive blood pressure monitoring with an arterial line, vessels are often positioned atypically in the forearms of achondroplastic patients. Ultrasound can be particularly helpful for this reason.
Conclusions
This case demonstrates the feasibility of MV repair in a patient with achondroplasia. There are few reported cases of cardiac surgery in these patients, but the intraoperative surgical and anesthetic course can be standard. Further investigation into the prevalence and prevention of cardiovascular disease in this patient population is needed.
Funding Support and Author Disclosures
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Take-Home Message
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•
This case demonstrates important considerations when preparing for and performing cardiac surgery in patients with achondroplasia.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
For supplemental videos, please see the online version of this paper.
Appendix
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Intraoperative midesophageal 4-chamber view transesophageal echocardiogram sweeping from lateral to medial across the mitral valve showing flail segment of the posterior leaflet (P2) displaced into the left atrium during systole. (Right) Color Doppler showing severe mitral regurgitation.
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Intraoperative midesophageal long-axis view transesophageal echocardiogram showing a flail segment (P2) of the posterior mitral leaflet. (Right) Color Doppler showing severe mitral regurgitation.
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Intraoperative midesophageal 4-chamber view transesophageal echocardiogram showing mitral valve after repair with annuloplasty ring and artificial cords. (Right) Color Doppler showing no evidence of residual mitral regurgitation.
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Intraoperative midesophageal long-axis view transesophageal echocardiogram showing mitral valve after repair with annuloplasty ring and artificial cords. (Right) Color Doppler showing no evidence of residual mitral regurgitation.
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Associated Data
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Supplementary Materials
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Intraoperative midesophageal 4-chamber view transesophageal echocardiogram sweeping from lateral to medial across the mitral valve showing flail segment of the posterior leaflet (P2) displaced into the left atrium during systole. (Right) Color Doppler showing severe mitral regurgitation.
Xxx
Intraoperative midesophageal long-axis view transesophageal echocardiogram showing a flail segment (P2) of the posterior mitral leaflet. (Right) Color Doppler showing severe mitral regurgitation.
Xxx
Intraoperative midesophageal 4-chamber view transesophageal echocardiogram showing mitral valve after repair with annuloplasty ring and artificial cords. (Right) Color Doppler showing no evidence of residual mitral regurgitation.
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Intraoperative midesophageal long-axis view transesophageal echocardiogram showing mitral valve after repair with annuloplasty ring and artificial cords. (Right) Color Doppler showing no evidence of residual mitral regurgitation.