Hypertrophic obstructive cardiomyopathy was once called subaortic myocardial infarction, and Davies reported in 1952 that five of nine siblings in a family had this disease, three of whom died suddenly. After 1960, it was considered a type of primary cardiomyopathy, accounting for about 20% of all types of cardiomyopathies, and thus was called idiopathic obstructive cardiomyopathy, idiopathic hypertrophic subaortic stenosis, or hypertrophic obstructive cardiomyopathy. The disease has a family history in about 30% of cases and may have a genetic component. The time of onset can range from infancy to more than 60 years of age, but most commonly between 10 and 30 years of age, suggesting that it may be a congenital anomaly or acquired. goodwin, Kelly, Morrow, Brockenbrough, Braunwald, Wigle, and others have been surgically treating this disease since 1960. Etiology The degree of left ventricular obstruction in hypertrophic obstructive cardiomyopathy varies. Typically, the most significant lesion is hypertrophy of the upper ventricular septum, and the hypertrophied myocardium expands into the left and right ventricular chambers when the septum is cut longitudinally. The thickest part of the septum is below the free edge of the anterior mitral leaflet, where the septum shows limited fibrotic endothelial thickening due to interfering with the anterior leaflet. The thickness of the hypertrophied septal myocardium gradually decreases upward (aortic annulus) and downward (apical region), and the inferior left ventricular outflow tract obstruction is located between the hypertrophied septal myocardium and the free edge of the anterior leaflet. During cardiac systole, the hypertrophied septum projects into the ventricular cavity near the anterior mitral leaflet, resulting in narrowing of the left ventricular outflow tract, sometimes with incomplete closure. Outflow tract obstruction is mild in early systole, when ventricular blood flow is high. The left ventricular free wall is uniformly thickened in the anterior and external parts of the apical region, while the posterior wall of the left ventricle is less thickened, and the ratio of the septum to the posterior wall of the left ventricle can be 3:1, with a smaller left ventricular cavity. The thickening of the middle part of the ventricular septum results in a dumbbell-shaped ventricular cavity. In advanced stages of the disease, due to myocardial infarction or prolonged severe heart failure, the left ventricle may be enlarged, the left atrial cavity is often enlarged, the atrial wall is thickened, and the anterior mitral valve leaflet is thickened, which may be accompanied by tendon rupture or congenital malformation. The right ventricle may have outflow tract obstruction due to protrusion of the hypertrophied ventricular septum into the right ventricle. The free wall of the right ventricle may be thickened by obstructive lesions or by increased pressure in the pulmonary circulation in long-standing cases. The walls of the coronary branches of the ventricular septum and ventricular wall are often thickened and the lumen is narrowed, which may lead to transmural myocardial obstruction. Clinical manifestations Clinical symptoms include shortness of breath after exertion, fainting or dizziness, and angina after activity, similar to aortic stenosis. In about 10% of cases, paroxysmal or persistent atrial fibrillation causes palpitations or embolism of the body circulation. In advanced cases, congestive heart failure, telangiectatic breathing, and pulmonary edema are present. Common signs include an increased apical pulsation, shifted to the lower left, and a common elevated or double impulse. A mid-systolic jet murmur can be heard in the lower left sternal border or in the apical region, conducted to the base of the heart and often accompanied by tremor. In cases with mitral valve insufficiency, a full systolic murmur is heard in the apical region, with a split second heart sound, and a third or fourth heart sound may be heard. However, no systolic jet-like klaxon is heard. The peripheral arterial shock wave is strong and the disappearance wave is small, similar to the water rushing pulse. Chest X-ray: enlarged heart shadow, enlarged left ventricle, but no signs of enlarged ascending aorta or calcification of valve leaflets. In advanced cases, the left atrium and right ventricle may also be enlarged, and the blood vessels in the lung fields are depressed. Electrocardiogram: It shows left ventricular hypertrophy and strain, sometimes with abnormal Q waves in anterior chest aVL and I leads. In some cases, complete right bundle branch, left bundle branch or left anterior hemibranch block and left atrial hypertrophy are present. Cardiac catheterization: Right heart catheterization may show signs of elevated pulmonary artery pressure or right ventricular outflow tract stenosis. Left heart catheterization shows a significant increase in left ventricular end-diastolic pressure and a systolic pressure step difference between the left ventricular cavity and the outflow tract. The aortic or peripheral artery pressure waveform shows a rapid rise in the ascending branch, showing a double peak, followed by a slow decline. Aortic pulse pressure decreases after ventricular extrasystole. Increased myocardial contractility and increased left ventricular outflow tract obstruction after nitroglycerin, isoamyl nitrite, isoprenaline, digitalis, and physical exertion and Valsalva maneuvers may lead to increased murmur loudness and systolic pressure gradient. Selective LV angiography may show a hypertrophied septum and anterior mitral leaflets in the posterior wall of the outflow tract, a curved left ventricular cavity, a small end-systolic left ventricular volume, and a thick papillary muscle. Left ventriculography can also determine the presence or absence of mitral valve insufficiency. In adult patients, coronary angiography is recommended for the presence of coronary artery lesions. Echocardiography shows significant thickening of the left ventricular wall, a thicker septum than the posterior ventricular wall, a small left ventricular cavity, narrowing of the outflow tract, and forward displacement of the anterior mitral leaflet during cardiac contraction. Surgical treatment Hypertrophic obstructive cardiomyopathy can present at any age, with the most common age of onset being around 20 years of age. Only 10% of cases diagnosed by cardiac catheterization present with severe symptoms under the age of 10 years, increasing to 70% over the age of 50 years. In some cases, the disease may remain stable for many years or continue to progress and become more severe. The onset of AF often presents with congestive heart failure or embolism of the body circulation. Approximately 15% of cases presenting with clinical symptoms and arrhythmias without surgical treatment die after 5 years and 25% die after 10 years. Most patients die suddenly, and only a few die from heart failure or infective endocarditis. If the clinical symptoms are obvious, medical treatment fails, and the systolic pressure difference between the left ventricular cavity and the outflow tract at rest exceeds 6.6 kPa (50 mmHg), surgical treatment should be performed to remove the hypertrophied myocardium of the ventricular septum to relieve the obstruction. The commonly used surgical methods are: 1. Combined aortic and left ventricular myocardial resection through a combined aortic and left ventricular incision median sternotomy, application of extracorporeal circulation combined with hypothermia, the left atrium into the decompression drain, block the ascending aorta, inject cold cardiac arrest fluid under pressure at its root and locally reduce the myocardial temperature, lateral incision of the ascending aorta root, pull the right coronary valve forward with a pull hook, use a round-bladed knife to remove the U-shaped myocardium from the front of the ventricular septum The incision begins below the right coronary valve and extends to the left below the junction of the right and left coronary valves. It is important not to extend the septal incision to the right, as this may damage the left atrioventricular bundle and cause complete conduction block. The septal rectangular myocardial slice is elongated inferiorly under direct visualization, but not too deeply. Another oblique incision of approximately 4 cm in length parallel to the lowest oblique branch is made in the lower part of the anterior wall of the left ventricle to enter the left ventricular cavity below the anterior papillary muscle, and the anterior valve leaflet is pulled to the left side of the ventricular septum through the incision, and the hypertrophied myocardium of the ventricular septum is removed from below and upward with a small knife to join the transaortic resected myocardial piece, and then the whole hypertrophied myocardium is cut off. embolism. The full myocardial incision is intermittently sutured, and the aortic incision is sutured. The left ventricular cavity and residual gas in the aorta are drained, the aortic blocking forceps are removed and the body temperature is raised, and the extracorporeal circulation is stopped after the heart beat is strong. 2.Transcatheter aortic incision ventricular septal myocardial resection and dissection Establish extracorporeal circulation and take myocardial protection measures, block aortic blood flow through the root of the ascending aorta transverse incision, tract the right coronary valve to reveal the ventricular septum, use a small circular knife to make two parallel incisions in the upper part of the ventricular septum below the right coronary valve, when cutting the lower part of the ventricular septum, the right ventricular free wall can be compressed, so that the ventricular septum moves to the left ventricular cavity to improve the exposure, and then resect The rectangle of hypertrophic myocardial tissue between the two parallel incisions is then removed. Finger pressure is applied to the septal incision to increase the depth and width of the septal groove, remove the myocardial debris, suture the aortic incision, drain the left ventricular cavity and intra-aortic gas, and remove the aortic blocking clamp. After rewarming to a temperature of 35℃ or higher and a strong heart beat, extracorporeal circulation is stopped. If the myocardial resection of ventricular septal hypertrophy is still considered unsatisfactory, it can be completely resected via the left ventriculotomy route.