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 thickness of the left ventricle can be 3:1, with a small 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 include shortness of breath after exertion, fainting or dizziness, and angina pectoris 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.
Ancillary examinations Chest X-ray.
The heart shadow is enlarged and the left ventricle is enlarged, but there is no sign of enlarged ascending aorta or valve leaflet calcification. 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 the anterior thoracic 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 or absence of coronary artery lesions.
Echocardiography.
It 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 of hypertrophic obstructive cardiomyopathy can present with symptoms 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. In patients with significant clinical symptoms, failure of medical therapy, and a systolic pressure difference between the left ventricular cavity and the outflow tract of more than 6.6 kPa (50 mmHg) at rest, 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
A median sternal incision is made, extracorporeal circulation combined with hypothermia is applied, a decompression drain is placed in the left atrium, the ascending aorta is blocked, cold cardiac arrest fluid is injected under pressure at its root and the myocardial temperature is lowered locally, the root of the ascending aorta is incised laterally, the right coronary valve is pulled forward with a pulling hook, and the U-shaped myocardium is removed from the front of the ventricular septum with a round-bladed knife, and the incision starts below the right coronary valve and extends to the left to the junction of the right and left coronary valves The incision begins below the right coronary valve and extends to the left to 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 a strong heartbeat.
2.Trans-aortic incision ventricular septal myocardial resection and dissection
Establish the extracorporeal circulation and take myocardial protection measures, block the aortic blood flow through the transverse incision of the root of the ascending aorta, tract the right coronary valve to reveal the ventricular septum, make two parallel incisions with a small circular knife 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 to make the ventricular septum move to the left ventricular cavity to improve the exposure, and then remove the rectangular hypertrophic myocardial tissue between the two parallel incisions.
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.