Diagnosis of prosthetic heart valve thrombosis. The respective values of transthoracic and transoesophageal Doppler echocardiography

Early diagnosis of acute prosthetic thrombosis remains a challenge. In 20 patients with 23 thrombosed cardiac valves, we evaluated the respective value of transthoracic (TTE) and transoesophageal (TEE) Doppler echocardiography. According to the presence or absence of prosthetic obstruction by continuous-wave Doppler, prostheses were separated into two groups. Group 1 included nine thrombosed prostheses (8 mitral, 1 aortic) with severe obstruction. All patients presented with severe symptoms of heart failure. Transthoracic Doppler echocardiography allowed immediate diagnosis of prosthetic thrombosis, even in critically ill patients, showing (1) eccentric transprosthetic colour flow jets in all eight mitral prostheses, (2) severe obstruction on Doppler examination (mean gradient = 18 to 36 mmHg in eight mitral prostheses, and 69 mmHg in one aortic valve), and (3) direct echocardiographic evidence of thrombosis (i.e. thrombus or abnormal disc or leaflet motion) in four patients. All nine patients were immediately treated by surgery (n = 8) or fibrinolysis (n = 1) on the basis of TTE results only. TEE allowed better visualization of thrombus and restricted leaflet or disc motion, but had little influence on patient management. Group 2 included 14 thrombosed prostheses (10 mitral, 4 aortic) with mild or absent obstruction. In three patients with massive mitral prosthetic thrombosis, an associated minimal thrombosis of a prosthetic aortic valve was found at surgery, but was detected neither by TTE, nor by TEE. The 11 remaining patients with isolated partial mitral (n = 10) or aortic (n = 1) thrombosis. Clinical presentation was fever, cerebral embolism, or mild dyspnoea, but no heart failure. TTE was normal in all.(ABSTRACT TRUNCATED AT 250 WORDS)

[Plasma glycosylated residues demonstrated by proton NMR spectroscopy. Value in the detection of heart graft rejection]

In conjunction with biopsy and Doppler studies, we analysed by high resolution proton NMR spectroscopy the blood plasma of 22 heart transplant recipients. There was a significant variation in the glycosylated residues of proteins with the development of acute cardiac rejection. A more extensive study is underway to assess the sensitivity and specificity of this approach for the early diagnosis of acute cardiac rejection.

[Right intra-atrial extension of hydatid cyst mimicking cardiac thrombosis. Apropos of a case]

The authors describe an unusual case of hydatid cyst inserted in the inferior vena cava and extending into the right atrium. The transoesoesophageal echocardiographic appearances were similar to those of a thrombus: the tumour was very mobile, echogenic, polylobular with a cord-like pedicle in the inferior vena cava. The pathological examination revealed a ruptured hydatid cyst. The mass and its insertion were not visible on CT scan or cavography. Transoesophageal echocardiography would therefore seem to be a very useful diagnostic method for tumours arising in the inferior vena cava and extending into the right atrium.

First significant animal survival with a Wankel-type left ventricular assist device

The authors' laboratory is developing a device for heterotopic left ventricular assistance. It consists of a titanium Wankel-type rotary pump, driven by an hermetically sealed electric motor. In our animal experiments, the motor-pump unit was implanted in the thoracic wall. The pump was connected to the left heart chambers by left atrial cannulation, and to the descending aorta. The motor was connected to the power and control unit by an electric wire through the skin. In this report, the authors describe the first significant animal survival with this system. Laboratory results were encouraging for hemolysis. The pump failed at 13 days due to a deposit of fibrin and blood cells in the gear housing. This problem was not surprising since similar events have been encountered with centrifugal devices. However, further design improvements should allow longer animal survival and clinical application.

Control of pulsatile rotary pumps without pressure sensors

When ventricular assistance is achieved with a volumetric pump driven by an electric actuator, overpumping can cause venous collapse. To prevent this problem, pump speed must be monitored and controlled. The authors developed a regulatory system based on the current intensity signal from the electric motor. This signal is processed and compared with predicted values calculated according to a mathematical model at the beginning of each ejection phase. If a difference is detected, pump speed is adequately adjusted. The great advantage of this system is elimination of the need for an implantable pressure sensor. It requires a simple and ubiquitous electronic component, i.e., a resistor, that can be easily integrated into the motor control circuit and does not require calibration.

[Surgical treatment of right-sided infective endocarditis]

Between 1980 and 1989, 8 patients (5 men, 3 women; mean age 30 years) were operated upon in our department of right-sided infective endocarditis. Six patients were heroin addicts and among these 3 were HIV positive and 2 had confirmed AIDS. The most frequently encountered microorganisms (6 cases) were staphylococci. It was decided to operate because of persistent infection and haemodynamic deterioration. The infection involved the pulmonary valve in only 1 of the 8 patients. Surgery was performed during the acute phase in 5 patients and was conservative in 6 patients, consisting of excision of the vegetations or valvulectomy combined or not with valvuloplasty. A high mortality rate (3/8 cases) was observed only among patients operated upon in the acute phase. This may be due to the underlying immunodeficiency and poor haemodynamic state of these patients. Among survivors, the long-term results were excellent, with no recurrent endocarditis and no death, and with only one subsequent operation, 4 years after the first one, for residual tricuspic valve regurgitation. This study shows that patients with right-sided infective endocarditis should be operated upon outside the acute phase of the disease and as soon as complications appear, and that surgery should preferably be conservative.

Another way of pumping blood with a rotary but noncentrifugal pump for an artificial heart

This article describes an alternative mode of pumping blood inside the body. The device is a non centrifugal, valveless, low speed rotary pump, electrically powered, based on Wankel engine principle. The authors developed an implantable electrical actuator resulting in a compact, sealed motor-pump unit with electrical and magnetic components insulated from fluids. The results in the flow curve and in the pumping action show some common points but also some basic differences compared to classical pulsatile pumps or centrifugal pumps. The blood coming from the atrium follows a continuous movement without any stop flow but with variations creating pulsatility. Ejection and filling of the pump are simultaneous. It is always an active filling. Hydraulic efficiency depends on clearance in the pumping chamber and outlet port pressure. A 60 cc device allows flows up to 8-9 liters. The implantable motor is cyclindrical in shape, has a moderate weight (490 grams) and presents a good efficiency (32% for a rotary speed of 90 rpm against a mean aortic pressure of 150 mm of Hg). The authors conclude that their device could be proposed after further experimental studies, as an LVAD for shortterm assistance with a good promise for permanent application.

Thromboembolytic complications during circulatory assistance with a centrifugal pump in patients with valvular prostheses

This article describes two patients with artificial heart valves who suffered thromboembolytic complications during circulatory assistance using a Biomedicus centrifugal pump. The first case involved a 25-year-old man who presented acute blockage of a mechanical aortic valve. Emergency surgery was performed to replace this valve with a bioprosthesis. Postoperatively the patient developed severe left heart insufficiency and a Biomedicus centrifugal pump was placed between the left atrium and the ascending aorta. After 3 days of total left ventricular assistance, weaning was started and successfully completed with explanation on the 5th day. Two days later the patient died of multiple coronary embolism with thrombosis of the valve. The second case involved a 30-year-old man. Six months before, he underwent surgical procedure with placement of Bio-prosthesis for dissecting aortic aneurysm due to annuloectasia. Upon admission for terminal dilated myocardiopathy, the patient was in kidney failure almost requiring dialysis. Because of this patient's size (Marfan syndrome), no donor heart was immediately available and left circulatory assistance with a Biomedicus pump had to be initiated. The patient lived without mechanical ventilation, in good clinical condition until day 23 when he presented acute right heart failure due to extensive valvular and coronary thrombosis. From these two cases, several important comments can be made about anticoagulation therapy, partial unloading of left ventricle, or need for biventricular assistance, and efficiency of centrifugal devices in these clinical applications.

[Approaching the posterior wall of the aortic arch. Temporary division of the innominate artery]

Two cases of wound affecting the posterior wall of the aortic arch are reported. One wound occurred during mediastinoscopy, the other was caused by a bullet. During surgery under extracorporeal circulation, the approach and repair of the wounds was greatly facilitated by temporary division of the innominate artery: the ascending and horizontal portions of the aorta could be tilted to the left, giving a very satisfactory access to the posterior wall of the arch. The innominate artery was easily repaired, without neurological complications. The authors insist on the convenience of this technique to approach not only the aortic arch but also various mediastinal organs, such as the tracheal bifurcation, the right branch of the pulmonary artery and the roof of the left atrium.

[18 and one-half years' survival after cardiac graft. Clinical course and anatomical findings]

Operated upon in November, 1968, the last survivor of heart transplant recipients in those times has died on May 11, 1987, having survived 18 years and 6 months. The active life of this patient, however, was marred by episodes of graft rejection during the first post-operative years and by various incidents. It was mainly the complications of the immunosuppressive treatment that hampered his activities (osteoporosis) and provoked his death. Post-mortem examination confirmed that the heart was in good condition, found an active bronchial epithelioma and revealed iatrogenic lesions, namely adenomas, adenocarcinoma of the kidney and "regenerative" nodular hyperplasia of the liver with portal hypertension. Such lesions are observed in patients under long-term treatment with immunosuppressants. A "sleep apnoea" syndrome might have accounted for the formation of pulmonary hypertension lesions. The authors wish to pay their respects to this man who devoted himself to the service of other men.

[Use of elastic laces with attached needle in coronary surgery]

Using elastic laces with attached needle for surgery of the coronary arteries ensures adequate exposure, presentation and drying up of these vessels during distal anastomosis.