番茄社区

"Medical Journeys" is a set of clinical resources reviewed by physicians, meant for the medical team as well as the patients they serve. Each episode of this journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.

This month: A noteworthy case study.

Why has this 32-year-old man been having palpitations and exertional dyspnea (New York Heart Association class III) for the last 2 years? That's what Jianmin Yang, MD, PhD, of Qilu Hospital of Shandong University in China, and colleagues needed to determine when the patient was referred to their center.

As they reported in , after taking his history, they learned that several members of the patient's family had a history of hypertrophic cardiomyopathy (HCM). The patient's medical history included tuberculosis, which had been cured 13 years previously, and he also noted that he developed hypertension about a month previously; at its highest, his blood pressure had reached 167/108 mmHg.

He had a 3/6 ejection murmur, which clinicians noted became worse with the Valsalva maneuver. Physical examination showed that his respiratory function was normal. The patient underwent a 24-hour ambulatory electrocardiography, which showed paroxysmal atrial tachycardia.

Transthoracic echocardiogram showed:

• Interventricular septum thickness of 18 mm

• Resting left ventricular outflow tract gradient of 60 mmHg

• Moderate mitral regurgitation with evidence of systolic anterior motion of the mitral leaflet

• Cardiac troponin I was within a normal range (8.08 ng/L).

The patient had been treated with metoprolol for 8 months before he was referred, clinicians learned, and his heart rate had been maintained at about 60 bpm. The patient also explained that he had been prescribed various other medical treatments, none of which had provided any symptomatic relief.

Given the previous failure of medical therapies, persistence of severe symptoms, and high left ventricular outflow tract gradient, the coronary intervention team advised percutaneous transluminal septal myocardial ablation (PTSMA). This catheter-based technique, used to reduce interventricular septum hypertrophy, involves infusing pure ethanol into the septal branch to cause necrosis of the local thickened myocardium.

Yang and colleagues advised the patient about potential complications, including irregular heart rate, heart attack, myocardial infarction, coronary artery injury, and tamponade.

On day 5 of hospitalization, coronary angiography (CAG) showed no obvious coronary stenosis, and did not detect any evidence of epicardial coronary artery compression. Based on these findings, Yang and colleagues chose the first septal branch to perform PTSMA. The gradient fell to 14 mmHg immediately after the surgery.

Following the procedure, a 24-hour ambulatory electrocardiogram revealed sinus rhythm, occasional atrial premature beats, frequent accelerated ventricular escape beats, and ST-T changes. Clinicians monitored the patient in intensive care and his symptoms gradually improved. At 12 days post-surgery, he was discharged with prescriptions for metoprolol 166.25 mg daily and amlodipine 5 mg daily.

Two months after surgery, however, on day 70 after he had presented to hospital, his initial symptoms worsened, and he began having typical angina with activity. The team performed a transthoracic echocardiogram, which showed that the thickness of the interventricular septum was 13 mm and the left ventricular outflow tract gradient was 27 mmHg.

On day 80, the patient underwent another coronary angiogram to investigate the new-onset angina and the notable inconsistency of his symptoms and echocardiographic results. While the imaging did not show any obvious stenosis of the coronary arteries, clinicians did find luminal compression of approximately 90% during cardiac systole in the middle part of the left anterior descending artery.

To determine what was causing the luminal compression, the team followed up with coronary computed tomography angiography (CTA), which showed a myocardial bridge in the middle section of the left anterior descending artery. After 5 days of treatment with metoprolol 190 mg daily and diltiazem 60 mg daily, the patient's angina and exertional dyspnea were relieved.

Six months after he was discharged, the patient returned for a follow-up interview and reported that all symptoms were resolved and had not returned.

Discussion

With an estimated prevalence of 1 in 200 people to 1 in 500 people worldwide, represents the most common type of hereditary cardiomyopathy, Yang and co-authors explained. The condition presents as "increased left ventricular wall thickness which cannot be solely explained by abnormal loading conditions." About 30% of people with HCM develop , which occurs when the epicardial coronary arteries take an intramyocardial course.

PTSMA is an effective treatment for symptomatic HCM, the team noted, cautioning, however, that studies of this intervention have generally focused on the arrhythmogenic effects and mechanical complications, while the impact on myocardial bridge has not been explored.

"For the first time, we present a case of HCM treated with PTSMA in which the MB was exacerbated," the authors wrote. "In the distribution of MB, previous pathological investigation found in histopathological examination and fibrous scars in gross heart specimen."

The group suggested that regional myocardial scarring motor disturbance associated with PTSMA may be implicated in the deterioration of myocardial bridge, and noted that this particular patient's case is in contrast to previously reported successful of MB following PTSMA in a patient with HCM.

"Future research is needed on a larger number of populations to identify the hypertrophic cardiomyopathy patients complicated with myocardial bridge who can benefit from percutaneous transluminal septal myocardial ablation," Yang and co-authors concluded.

They suggested that indications for PTSMA should be strictly controlled, in particular in patients with MB. And in the future, characteristics from preoperative echocardiogram, coronary CTA, CAG, and cardiac magnetic resonance may help inform optimal treatment strategies.

Read previous installments in this series:

Part 1: Cardiomyopathy: What are the Signs, What are the Symptoms?

Part 2: Diagnosing Cardiomyopathy: History, Examination, and Testing

Part 3: Cardiomyopathy: Epidemiology, Etiology, and Pathophysiology