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Biomedical subjects

D Bregman

Publications and source records attributed to D Bregman.

At least 55 records · Page 3Linked to original sources
PubMed1979

Left ventricular mechanics of counterpulsation and left heart bypass, individually and in combination.

Counterpulsation and left heart bypass devices have been successfully used to salvage patients with severe left ventricular power failure following cardiopulmonary bypass. Each of these techniques is believed to reduce or minimize myocardial work, yet the effects of these devices on the force of myocardial contraction have not been defined. In the present investigation the effects of counterpulsation produced by intravascular (intra-aortic balloon pumping) and extravascular (pulsatile assist device) balloon devices, partial left atrial-aortic bypass, and total bypass on left ventricular mechanics were examined. The devices were studied individually and in combination in 10 anesthetized open-chest dogs. Left ventricular wall stress, external work, and contractility indices were calculated by computer using a changing volume spherical model of the left ventricle. Results indicate that although all currently available circulatory assist devices reduced peak left ventricular wall stress, a spectrum of relative effectiveness progressed from intra-aortic balloon pumping or pulsatile assist device alone through the combination intra-aortic balloon pumping plus the pulsatile assist device. Partial left heart bypass was more effective than intra-aortic balloon pumping plus the pulsatile assist device in reducing peak wall stress, but the difference was small. Total left heart bypass was vastly superior to any of the other modalities tested in its effects on peak wall stress as well as external work. The addition of counterpulsation to partial or total left heart bypass produced minimal changes in left ventricular systolic mechanics.

Animals↗
PubMed1978

Renovascular hypertension following surgical repair of dissecting aneurysm of the thoracic aorta.

A critically ill patient with refractory renovascular hypertension following successful intrathoracic repair of a type I aortic dissection was treated successfully with gelfoam embolization of the left kidney. Renal artery stenosis secondary to aortic dissection can exacerbate pre-existent hypertension in the preoperative or postoperative periods and can be diagnosed angiographically. Unilateral renal artery embolization may provide a safe alternative to nephrectomy for renovascular hypertension in cases where surgery is not feasible.

Aortic Dissection↗
PubMed1978

[Counterpulsation by means of a new device with a pulsatile blood flow in open heart operations (author's transl)].

A new counterpulsation method in operations on an open heart is described. Clinical experience in the use of the new device in 124 patients, which also makes it possible to produce a pulsatile flow of blood in the system of extracorporeal circulation, testifies to its effectiveness. The authors claim that the positive changes in cardiac output, diastolic and systolic pressure, and coronary circulation are among the factors which cause an improvement in the final result of the operation in patients with severe valvular diseases and ischemic heart disease.

Adult↗
PubMed1978

Mechanical circulatory support: evolving perspectives.

Mechanical circulatory support of the failing circulation is an emerging discipline. Prototype circulatory support services have been established in a few institutions but are spreading15. Intra-aortic balloon pumping, developmental only a decade ago, is now widespread. Pneumatically-actuated intra and extracorporeal left ventricular assist devices, federally-approved for clinical trials only 2 yrs ago, show encouraging early results. Efforts in West Germany, Austria, Switzerland, Russia and Japan are underway and a spirit of cooperation exists. There is a need to clarify and quantitate indications and timing for deployment, prior to the onset of multiple organ failure. Electrically and nuclear-activated LVAD's16--18 are being developed. Clarification of projected patient populations are needed and the role of the right heart in left ventricular assist device function requires further investigation. There is a need to define a reasonable clinical role for the much discussed and rather elusive total artificial heart. Many problems remain with actuation, energy conversion, percutaneous leads, compliance devices and biomaterials. The challenges are many and welcomed.

Assisted Circulation↗
PubMed1977

A pulsatile assist device (PAD) for use during cardiopulmonary bypass.

A pulsatile assist device (PAD) has been developed to convert roller pump flow to pulsatile flow in a simple fashion. The device can also be used as an arterial counterpulsator before and after cardiopulmonary bypass. The PAD has been used in 125 adult patients undergoing open-heart operations for coronary artery or valvular heart disease or the combination. Ninety-two patients were in New York Heart Association Functional Class III or IV or had ejection fractions of less than 0.3. The PAD functioned as a hemodynamically effective arterial counterpulsator before and after perfusion. All patients were successfully weaned from bypass with the PAD. There has been 1 intraoperative death and 2 late deaths. Only 1 patient had a perioperative myocardial infarction, and this person was successfully treated with intraaortic balloon pumping. We believe the PAD is a simple and reliable device for intraoperative counterpulsation and for the creation of pulsatile cardiopulmonary bypass. More important, use of the PAD may decrease both the incidence of perioperative myocardial infarction and the need for postoperative intraaortic balloon pumping.

Adult↗
PubMed1977

Intraoperative application of intraaortic balloon counterpulsation determined by clinical monitoring of the endocardial viability ratio.

Persistent unrecognized subendocardial ischemia with development of subendocardial necrosis is a major cause of patient death following cardiopulmonary bypass. The lesion is caused by a discrepancy between the oxygen needs of subendocardial muscle and the available blood supply. If sole reliance is placed upon monitoring conventional vital signs, the more subtle factors contributing to decreased blood flow may go unrecognized. Reported studies have confirmed that the adequacy of subendocardial perfusion can be predicted by calculating the supply/demand ratio, defined as the ratio of the diastolic pressure-time index (DPTI) divided by the systolic pressure-time index (TTI). An analog computer was designed and built that measures the area under the systolic and diastolic component, calculates the DPTI/TTI ratio, and digitally displays the result as the endocardial viability ratio (evr). The EVR was used to determine the adequacy of left ventricular subendocardial blood flow in 64 consecutive patients undergoing cardiac operations. Unidirectional intraaortic balloon counterpulsation (IABC) was utilized in 14 patients with 9 long-term survivors. The difference in mean EVR between survivors and nonsurvivors at the initiation of balloon support was statistically significant. Early application of unidirectional IABC when subendocardial ischemia persists following open cardiac procedures may prevent deterioration to subendocardial necrosis with subsequent morbidity or mortality.

Assisted Circulation↗
PubMed1977

Methods and results of mechanical myocardial support.

In recent years the development of modern direct techniques for revascularization surgery has resulted in a multitude of critically ill patients undergoing open heart surgery. To deal with the increasing numbers of patients who both require urgent open heart surgery and present with many complicated patterns of disease, a spectrum of cardiac assist measures, ranging from simple pharmacological interventions to mechanical cardiac assist techniques, has been developed. Those temporary mechanical cardiac assist devices which employ the principle of couterpulsation and balloon pummping have met with the most consistent clinical success. We now report our experience and progress in this field since early 19729

Adult↗