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Biomedical subjects

R Hetzer

Publications and source records attributed to R Hetzer.

At least 397 records · Page 22Linked to original sources
PubMed1983

Intracoronary nifedipine in human beings: magnitude and time course of changes in left ventricular contraction/relaxation and coronary sinus blood flow.

Eight patients, all men, having at least 75% stenosis of the proximal, middle or both segments of the left anterior descending coronary artery, underwent intracoronary drug studies at the time of cardiac catheterization after saphenous vein bypass grafting. Nifedipine, 0.1 mg dissolved in saline solution, was infused into a left anterior descending graft that was the primary blood supply to each patient's anterior left ventricular wall and septum. High fidelity left ventricular pressure and its first derivative, dP/dt, and aortic pressure were sampled synchronously with coronary sinus blood flow by the thermodilution technique. The time constant of isovolumic pressure decay (T) was derived. In five patients, percent systolic shortening and mean shortening velocity were determined from myocardial markers implanted into the midwall of the myocardium at the time of cardiac surgery. In response to nifedipine, left ventricular systolic pressure decreased and end-diastolic pressure increased up to 60 seconds. Both positive and negative dP/dt also decreased up to 60 seconds, whereas coronary sinus blood flow increased up to 5 minutes. T was increased at 1 minute but returned to baseline by 3 minutes. Percent systolic shortening and mean shortening velocity were decreased at 1 minute but returned to control level by 3 minutes. Thus, although both left ventricular systolic and diastolic function were depressed by intracoronary administration of nifedipine, coronary sinus blood flow was augmented and remained increased long after changes in left ventricular contraction and relaxation had subsided. These temporal differences are consistent with animal studies showing a differential depressant effect of nifedipine on calcium uptake in smooth muscle and cardiac muscle.

Adult↗
PubMed1983

Abnormal accessory mitral leaflet simulating left ventricular outflow tract tumor.

This is a case report of an uncommon form of subaortic stenosis caused by an abnormal accessory mitral leaflet simulating a left ventricular outflow tract tumor. A 5-year-old boy with a systolic heart murmur underwent cardiac catheterization which demonstrated a subaortic stenosis with a 90 mmHg peak systolic pressure gradient. Angiography showed a tumor-like structure in the left ventricular outflow tract. At operation this mass was found to be an abnormal bulky accessory mitral leaflet. Resection of this deformed leaflet was carried out successfully.

Angiocardiography↗
PubMed1983

Mitral valve replacement with preservation of papillary muscles and chordae tendineae - revival of a seemingly forgotten concept. I. Preliminary clinical report.

In 45 consecutive patients mitral valve replacement was performed leaving the posterior mitral leaflet and its chordal attachment to both papillary muscles intact (Lillehei's technique). Most patients showed moderate to severe pulmonary hypertension before surgery, 15 of the patients had double valve operations and 4 had a triple valve procedure. All patients survived and were discharged, the postoperative courses being remarkably uneventful with only very limited need of inotropic support in 3 patients and resumption of spontaneous respiration within the first 20 hours after the operation. The clinical courses in these patients seem to indicate that preserving the continuity between papillary muscles and mitral annulus in mitral valve replacement may improve left ventricular function at least early after surgery.

Adult↗
PubMed1983

[Changes in the quality of life after coronary revascularization].

The purpose of this study was to evaluate the change of quality of life after coronary revascularization. Out of 189 longterm survivors who underwent coronary revascularization between January 1979 and February 1980, 142 patients (134 men, 8 women) aged 36 to 71 agreed to cooperate in this study and to answer our questions. The questionnaire included 38 questions related to anginal pain, capacity for physical activity, employment, and psychological state. The change in the quality of life was assessed from the sum of changes in the variables. There was a significant improvement of angina in 82.4%, 81% were free of symptoms or in NYHA class I. 69.2% of those questioned claimed increased capacity for physical activity, and depression improved in 55.3%. The subjective improvement did not completely correlate with return to work, only 50.4% were working again after the operation. There was a significant relationship between reemployment and the period of unemployment before operation, as well as with the kind of employment. Quality of life was improved in 80.3% of the patients, unchanged in 10.5%, and poorer in 9.2%. From this study it may be concluded that coronary revascularization can improve the subjective feeling of well-being as well as physical symptoms.

Adult↗
PubMed1982

[The role of experiments in cardiovascular surgery].

In this presentation the essential historical steps of cardiovascular surgery are briefly described regarding the basic importance of experimental research. It is seen that each step in this development was programmed by substantial animal experiments. Surgical researchers often have borrowed basic knowledge and methodology from the most important sister science, physiology. However, the great break-throughs to new surgical methods always were achieved by original thoughts and innovative methods introduced by surgeons. On this long road there were many delays which sometimes are difficult to understand from our point of view, depending on psychological barriers, lack of communication between experimental innovators and clinicians and insufficient international distribution of new knowledge. Further progress in cardiovascular surgery, especially towards the perfection of cardiac replacement are to be expected and these again will only be possible on the basis of animal experimentation.

Animals↗
PubMed1982

[Use of the TDMAC heparin shunt for operations on the descending thoracic aorta (author's transl)].

This report summarizes our experience with the TDMAC heparin shunt for aortic bypass in descending thoracic aortic surgery. Between 1977 and 1981 twenty-four operations were performed with this shunt (19 men, 4 women, mean age 42 age). Indications for surgery were acute traumatic aortic rupture (6 patients), chronic aortic rupture (6 patients), acute aortic dissection (1 patient), chronic aortic dissection (4 patients), atherosclerotic aneurysms (3 patients), aortic aneurysms combined with PDA (1 patient), aortic aneurysm secondary to coarctation repair (1 patient), and infection of a vascular prosthesis (1 patient). Four patients died (hospital mortality 16.7%). One patient suffered perioperative paraplegia. In this patient the small size (7 mm) shunt hat been used. Therefore we suggest the large bore (9 mm) shunt be applied whenever possible, since even this larger size device displays a significant pressure gradient. When insertion of the shunt into the left subclavian artery is difficult, the ascending aorta or the apex of the left ventricle may be cannulated instead. In our cases we did not encounter any complications arising from shunt cannulation. The advantages of the TDMAC heparin shunt focus on the reduction of bleeding complications more common under systemic heparinization, and on less pronounced hemodynamic and metabolic sequelae following aortic clamping and declamping. With this shunt nearly all possible ischemic organ damage can be avoided.

Adult↗
PubMed1982

Aortic valve replacement and ascending aorta replacement in ankylosing spondylitis: report of three surgical cases and review of the literature.

Out of 887 consecutive patients who underwent aortic valve replacement between January 1976 and December 1981 at Hannover Medical School Hospital, 3 patients had severe aortic valve insufficiency associated with ankylosing spondylitis (Morbus Bechterew). One of them had huge aneurysmatic dilatation of the ascending aorta and successfully underwent replacement of the ascending aorta by a vascular prosthesis. Microscopical examination of the resected aortic wall showed characteristic findings of aortitis in ankylosing spondylitis. The 3 patients are in good clinical condition at 5 and 6 months, and 2 1/2 years, respectively, after uneventful surgery. It is concluded that aortic valve replacement in patients with ankylosing spondylitis can be performed feasibly and clinical results have been satisfactory. The risk of aneurysmatic dilatation of the ascending aorta resulting from aortitis associated with ankylosing spondylitis is emphasized.

Aorta↗
PubMed1982

Surgery for active infective endocarditis.

The results of 100 patients with primary active infective endocarditis treated surgically are presented. Hospital and late mortalities as well as postoperative complications in patients operated electively and not showing paravalvular infection approach those of routine procedures while frank circulatory failure and uncontrolled sepsis were associated with high death and complication rates. Paravalvular extension of the infection was associated with frequent postoperative leakage, reoperations and mortality. The present operative choices in eradicating paravalvular disease are described and the great importance of early operation is stressed.

Adolescent↗
PubMed1982

Blood velocity, flow and dimensions of aortocoronary venous bypass grafts in the postoperative state.

Intraoperative measurements have suggested an interrelation between the diameter of aortocoronary venous bypass (ACVB) grafts and the hemodynamic properties that may influence the functional results and long-term graft patency. We therefore studied the function of 35 nonobstructed ACVB grafts in 34 patients 1-59 months after bypass grafting. The mean blood velocity and flow were assessed using the roentgen videodensitometric technique. Graft diameters were obtained by morphometry from 35- or 70-mm cineangiograms taken in two orthogonal projections. The regional resistance of the graft-dependent area was calculated as mean aortic pressure/ACVB flow. The average graft diameter was 3.67 mm, the average graft-to-host vessel diameter ratio 1.5, the average ACVB blood velocity 8.5 cm/sec, the average flow 55 ml/min, and the average regional resistance 2.8 mm Hg/ml/min. No significant differences were observed for different graft locations or for different postoperative time intervals. Neither ACVB blood velocity nor flow correlated convincingly with graft size, but there was a significant inverse relation between graft diameter and the resistance of the graft-dependent area. We conclude that ACVB hemodynamics generally cannot be predicted by the dimensions of the graft in the postoperative state. Our data suggest that venous bypass grafts may adjust in size to the needs of the myocardial region supplied by the graft after operation.

Adult↗
PubMed1982

[Surgical revascularization in stenosis and occlusion of the left main coronary artery].

From 1975 through 1981 130 patients underwent coronary revascularization for significant stenosis or complete occlusion of the left main coronary artery (LMA). Hospital mortality was 4.6%, 3.3% were related to cardiac causes. The incidence of perioperative infarcts was 9.7%; in three fourths of these patients cardiovascular complications (e.g. hypertension, hypotension, arrhythmias) had occurred between start of anesthesia and start of extracorporeal circulation. Patients with a more than 90% LMA stenosis and complete occlusion of the right coronary artery appear to be at a particularly high risk both in terms of mortality and perioperative infarcts as compared to all other LMA-stenosis patients (operative mortality 15% vs. 3.5%, perioperative infarcts 15% vs. 8.8%). 3 patients with complete LMA occlusion did not suffer perioperative infarcts and survived in the long term. Follow-up investigation (mean 28.8 months) revealed late infarcts in 9 patients, 5 of which were lethal (late mortality 4.1%). Of hospital survivors, 88% were entirely asymptomatic or had very little angina pectoris (classes I and II NYHA). Cumulative survival was 84.3% at 5 years.

Angina Pectoris↗
PubMed1981

Intraoperative assessment of the reconstructed mitral valve using a low pressure crystalloid infusion.

A technique to intraoperatively assess mitral valve function after reconstruction is described. Cold cardioplegic solution is infused into the left ventricle at low intraventricular pressure (less than 15 mm-Hg) via the cardioplegia infusion line. The infusion of a crystalloid solution, instead of blood, clearly demonstrates residual leaks. Additional pump lines are not required and hypothermic cardioplegic arrest is maintained, thus allowing for repeated testing and additional repair. In combined aortic and mitral valve procedures, a Foley catheter is used to seal the aortic annulus and to infuse the crystalloid solution into the left ventricle. This method has been found to simplify mitral valve testing after reconstruction in a series of 25 patients since September 1979. Testing prompted additional repair in 4 patients and subsequent valve replacement in 2 patients.

Adolescent↗
PubMed1981

Re-excitation of the cardioplegic heart. A possible hazard in clinical cardioplegic arrest.

Clinical cardioplegic arrest may coincide with a washout of cardioplegic agents by varying amounts of extracoronary collateral blood flow. This may shorten the duration of electromechanical arrest. Furthermore, even in the absence of electromechanical cardiac activity, washout may influence the cardioprotective properties of cardioplegic methods. The present study was designed to quantify the effects of cardioplegic washout. In a standardized isolated paracorporeal dog heart model, the St. Thomas's Hospital solution (ST-CP) and the Bretschneider histidine buffered solution (B-CP) were compared under the condition of washout by arterial blood. An inverse relationship was found between the amount of blood flowing through the coronary system and the duration of electromechanical arrest. Flow rates compatible with a 100 min period of complete electromechanical arrest were less than 0.41 ml/100 gr heart weight . min in ST-CP arrest and less than 0.21 ml/100 gr . min in B-CP arrest. This would indicate a greater safety against washout-induced re-excitation in ST-CP arrest. Postarrest myocardial function after 2 hours of complete electromechanical arrest at 20 degrees C was distinctly influenced by washout with arterial blood (20 degrees C) even in the absence of cardiac activity. A 100-min period of 0.2 ml/100 gr . min blood flow during arrest improved postarrest recovery of left ventricular developed pressure by 10% (76% versus 66%) after ST-CP arrest. By contrast, after B-CP arrest at equal rates of washout, recovery was diminished by 20% (79% versus 99%). It is concluded, that ST-CP, as compared to B-CP, provides longer periods of electromechanical arrest under the same washout conditions. Whereas postarrest recovery in the B-CP group is clearly superior to ST-CP in totally ischemic hearts, i.e. in hearts without collateral blood supply (99% versus 66%), this advantage may vanish in the presence of cardioplegic washout.

Animals↗
PubMed1981

Complete occlusion of the left main coronary artery: report of three surgical cases and review of the literature.

Out of 75 consecutive patients with left main coronary artery (LMCA) obstruction who underwent coronary revascularization between January and October 1980, 3 patients had total occlusion of the LMCA. All 3 patients were suffering from severe angina pectoris preoperatively. On cardiac catheterization they had shown extensive collaterals from the right coronary artery and relatively well-preserved left ventricular function. In addition to intercoronary anastomoses a relatively high extracoronary collateral blood flow was measured at operation. Postoperatively the 3 patients remained free of angina (class I NYHA) at 5, 20 and 50 months after uneventful surgery. It is concluded that patients with adequate intercoronary and extracoronary collaterals may well survive complete occlusion of the LMCA. Surgery appears to carry a low risk no greater than that involved in conservative treatment of LMCA stenosis and the postoperative clinical status of the patients continues to be satisfactory.

Adult↗
PubMed1980

Extracoronary collateral myocardial blood flow during cardioplegic arrest.

Extracoronary blood flow to the myocardium was studied in 54 patients during cold cardioplegic arrest. Coronary venous return was measured with the aorta and the pulmonary artery cross-clamped, both venae cavae occlusively snared, and the heart completely drained. Cold St. Thomas' cardioplegic solution was infused into either the aortic root or the coronary ostia. Myocardial septal temperature was continuously monitored. The amount of blood in the right atrial effluent was determined by means of the hematocrit and was considered to be the extracoronary collateral myocardial blood flow (QE), originating from the systemic circulation. QE ranged from 0 to 1470 ml-100 min-1 (x = 241.1 ml-100min-1). The myocardial spontaneous rewarming rate was not significantly correlated to QE. QE was lowest in pure mitral valve stenosis (x = 39.9 ml-100 min-1) and higher in aortic valve disease (x = 165.5 ml-100 min-1). Very high QE values (greater than 800 ml-100 min-1) were only observed in patients with severe three vessel coronary artery disease. Patients with angina at rest appear to have lower QE values than patients with equally severe coronary artery disease suffering from angina under excise only. It is concluded that extracoronary collateral blood flow may unpredictably influence the efficacy of clinical cardioplegia and may to some extent compensate for severe coronary artery disease.

Aortic Valve↗
PubMed1980

Surgery for traumatic rupture of the thoracic aorta.

Between 1975 and 1980, 9 patients with traumatic rupture of the thoracic aorta were operated at our institution. All patients showed additional multiple limb and internal organ injuries. Leading symptoms of aortic rupture were mediastinal widening (8), left-sided hemothorax (6), and acute aortic coarctation (2). Aortic rupture was proven by angiography in 8 patients and during exploratory thoracotomy in another. The time interval between trauma and operation was one to 48 hours, in 6 patients less than 4 hours. Atrio-femoral bypass was used in 3 patients, TDMAC-heparin shunt in 4 patients and 2 patients were operated without bypass. Prosthesis interposition was required in 3 patients while direct suture was possible in 6 patients. Long-term survival was achieved in 7 patients, one patient died from shock sequelae and another had suffered inoperable multiple rupture along the ascending and transverse aorta. It is concluded that patients with traumatic aortic rupture have a relatively good prognosis if diagnosis is established immediately and if surgery is feasible. The operative result is influenced substantially by the degree of preoperative shock and the presence of additional injuries.

Accidents, Traffic↗