Temporary intravascular shunts for peripheral vascular trauma.

Polyvinylchloride (PVC) disposable endotracheal suction catheters were successfully used as temporary intravascular shunts in 5 patients of popliteal artery trauma. These simple shunts should be used routinely in such conditions to immediately re-establish blood supply to the ischaemic limb particularly in patients of polytrauma where systemic anticoagulation is contraindicated. This avoids the inherent delay prior to vascular repair and reduces the incidence of irreversible ischemia.

Impedance plethysmography of thoracic region: impedance cardiography.

Impedance plethysmograms were recorded from thoracic region in 254 normal subjects, 183 patients with coronary artery disease, 391 patients with valvular heart disease and 107 patients with congenital septal disorder. The data in 18 normal subjects and 55 patients showed that basal impedance decreases markedly during exercise in patients with ischaemic heart disease. Estimation of cardiac index by this technique in a group of 99 normal subjects has been observed to be more consistent than that of the stroke volume. Estimation of systolic time index from impedance plethysmograms in 34 normal subjects has been shown to be as reliable as that from electrocardiogram, phonocardiogram and carotid pulse tracing. Changes in the shape of plethysmographic waveform produced by valvular and congenital heart diseases are briefly described and the role of this technique in screening cardiac patients has been highlighted.

Evaluation of state of circulation in radiation injury using impedance plethysmography.

Seven patients with history of radiation burn were subjected to impedance plethysmographic investigation at Non-invasive Vascular Laboratory, K. E. M. Hospital. Impedance plethysmograms were recorded from various locations in both the upper extremities in supine and digits of both the hands in supine as well as on hyper-abduction in sitting position. Control values of blood flow index (BFI) and differential pulse arrival time (DPAT) were derived from similar data in 15 normal subjects. It was observed that digits having thinning of epidermis of skin recorded marked decrease in values of BFI and significant change in value of DPAT and these observations correlated well with thermography and vascular scintigraphy. Digits recording significant decrease in BFI, which were clinically normal, were found to have changes in the skin during follow up examination. Thus IPG provided a sensitive modality for detecting ischaemia in early stages in patients with history of radiation injury.

Effect of pulmonary circulation on vector impedance cardiogram.

Vector impedance cardiograms in horizontal lead configuration [VICG(H)] were recorded in 34 normal subjects, 18 patients with mitral stenosis, 9 patients with mitral regurgitation, 14 patients with aortic regurgitation and 13 patients with non- cyanotic septal disorders. Data in normal subjects revealed that most of the phase reversal points in VICG(H) waveform did not coincide with those of conventional impedance cardiogram. The shape of VICG(H) waveform and values of VICG indices were observed to be markedly affected in patients having significant alteration in the pulmonary circulation and the changes observed were specific of the type of the disorder. The results of the study suggested that right side of the heart had dominant contribution in generation of VICG(H) waveform.

Diagnosis of peripheral arterial occlusive diseases using impedance plethysmography.

Impedance plethysmographic observations have been compared with arteriographic findings in 216 patients with peripheral arterial occlusive diseases. Impedance plethysmographic diagnosis in these patients was obtained by Parulkar's method without apriori knowledge of arteriographic diagnosis. But for minor discrepancy in the anatomical location of the block in few patients, impedance plethysmographic observations correlated very well with arteriographic findings. Impedance plethysmographic diagnosis was found to be correct in 312, wrong in 53, false negative in 8 limbs respectively, yielding a sensitivity of 97.5% and specificity of 98.1% of this technique.

Diagnosis of venous disorders using impedance plethysmography.

Impedance plethysmography (IPG) was carried out in one hundred and forty-one patients suspected of venous disorders using Parulkar's method. In these patients occlusive impedance phlebography (OIP) and venography were also carried out using standard procedures. Comparison of IPG and OIP observations with venographic findings revealed sensitivity of these methods to be 65% and 77.7% in the diagnosis of primary varicosity of veins and chronic deep vein thrombosis respectively with a specificity of 85%. Occlusive impedance phlebograms showing unilateral decrease in OIP parameters were observed to be sufficiently diagnostic. IPG observations in 5 patients with arterio-venous malformation were observed to be different from those in patients with deep vein thrombosis.

Impedance plethysmographic observations in thoracic outlet syndrome.

Forty patients with symptoms of neuro-vascular compression in the upper extremities were subjected to impedance plethysmographic study using Parulkar's method. Two patients recorded decreased blood flow (BFI) in supine position and were diagnosed as having partial occlusion at subclavian level. Sixteen of the patients recorded decreased BFI on 90 degrees abduction and hyper-abduction. Twelve of these patients had radiological evidence of anomalous cervicle ribs. In remaining four patients extrinsic impression on the subclavian artery due to fibrous deposits was confirmed by arteriography. Remaining 22 patients recorded normal impedance plethysmograms. Impedance plethysmography thus provided a non-invasive modality for confirmation of vascular compression in thoracic outlet syndrome.

Diagnosis of aortic occlusive diseases using impedance plethysmography.

Impedance plethysmographic observations have been correlated with aortographic observations in 57 patients suspected of aortic occlusive diseases. Aortic occlusions have been characterised by marked decrease in blood flow index and significant increase in differential pulse arrival time at thigh level bilaterally. Atherosclerotic affection of the aorta has been featured by a bilateral decrease in the value of blood flow index as well as differential pulse arrival time at thigh level. Leriche's syndrome, however, has been found to decrease the blood flow index moderately at thigh in both the legs without any significant change in differential pulse arrival time. Aortography in all the patients has confirmed the diagnosis made by impedance plethysmography.

Physiological correlates of impedance plethysmographic waveform.

A review of investigations into the origin of impedance plethysmographic waveform is presented in this article. Attempts made by several investigators in the comparison of impedance plethysmographic estimations of peripheral blood flow with that obtained by standard methods are briefly described. Investigations indicating the negligible contribution from contact impedance at body electrode interface are highlighted. Temporal correlation of impedance plethysmographic waveform recorded from thorax with various important events of the cardiac cycle is summarised and various hypotheses on the genesis of this waveform are presented.

Impedance plethysmography: basic principles.

Impedance Plethysmography technique has been discussed with explanation of two compartment model and parallel conductor theory for the estimation of peripheral blood flow and stroke volume. Various methods for signal enhancement to facilitate computation of blood flow are briefly described. Source of error in the estimation of peripheral blood flow is identified and the correction has been suggested.

Technical aspects of impedance plethysmography.

This paper describes the basic methods for measurement of body impedance, electrodes and their configuration, and the measuring instrument with its limitations. A microcomputer assisted impedance plethysmograph system, developed at BARC and different lead configurations for impedance plethysmographic investigation are also described. Typical impedance plethysmographic waveforms recorded from a normal subject and measurement of their amplitude and various time intervals are illustrated.

Repeat open intracardiac operation--analysis of 55 patients.

Of the 4170 open intracardiac operations performed at our hospital in the last 6 years, 55 (1.3%) were reoperations. Of these failed valve repairs or valve substitutes formed the major group (58%) and the interval between first and second operation ranged from 6 months to 8 years. There were 4 deaths on table and another 6 patients died during their hospital stay giving an early mortality rate of 18 per cent. There was one late death during a follow-up period of 1 month to 3 years. There was no death due to perioperative bleeding complications. We conclude that it should now be possible to perform reoperations with an acceptable mortality and good late functional results.

A study of lung function and oxygen uptake during exercises in cases undergoing mitral valve surgery.

In 1986-7, 80 cases with isolated mitral valve disease undergoing open heart surgery were studied, for spirometry, resting and exercise, oxygen uptake (VO2) preoperatively and 3 months postoperatively. Pulmonary artery pressures (PAP) were recorded prior to surgical correction and soon afterward. Pulmonary hypertension was mild (I) in 56.2%, moderate (II) in 25% and severe (III) in 18.8% cases. Though spirometric functions were lower with severe PH, these did not improve significantly 3 months later. But direct MBC improved significantly in grs. I and II, along with exercise VO2 and mean PAP. (DMBC:75.7 lit. to 91.8 lit: P less than 0.001; Exercise VO2 798 ml to 983 ml: P less than 0.001). Mean PAP 56.8 to 39.5 mm: P less than 0.001). Thus these functions may be used to objectively evaluate physiologic changes in cardiac surgical cases.

Blood cardioplegia--a comparative clinical and laboratory study.

A prospective comparative study was undertaken to determine quality of myocardial preservation during open heart surgery by crystalloid and blood cardioplegic solutions. Total 55 consecutive patients were studied. Alternate patients received blood and crystalloid cardioplegia at random. Group I had 30 patients who received crystalloid cardioplegia, and group II, with 25 patients, received blood cardioplegia. The efficacy of two solutions was assessed by serum enzyme estimation of creatinine phosphokinase, M.B. fraction of creatinine phosphokinase and serum glutamate oxalate transferase (CPK, CPK-MB, SGOT), electron microscopic study of Left Ventricular biopsy and clinical assessment of post anoxic cardiac performance. Group II patients had lower serum enzyme levels, lesser microscopic myocardial damage, and better cardiac performance during immediate post-operative period, thus proving superiority of myocardial protection by blood cardioplegia.

Ascending aortic aneurysm with aortic valve incompetence--surgical management.

Aneurysm of ascending aorta with aortic valve incompetence is a formidable pathological entity having a relentless course. Etiological factors include syphilitic aortitis, dissection of aorta, Marfan's syndrome and similar conditions. With the advance in operative technique and extra corporeal circulation, now it is possible to treat these conditions by surgery. Surgical intervention includes replacement of entire ascending aorta along with aortic valve by an artificial valve conduit. Basically, two procedures are described, namely, the conventional method and Bentall's operation, both involving a great technique challenge. Our experience with both these techniques is being described in four consecutive cases in the last one year.