Coronary and left ventricular pacing as standby in invasive cardiology.

Coronary pacing using as unipolar negative electrode a guidewire placed in a coronary branch was tested in 349 sites of 300 consecutive patients undergoing coronary angioplasty. It was possible for 339 sites (97%). The threshold currents ranged from 1 to 15 (mean +/- standard deviation 3.4 +/- 2.4) mA. Side effects were seen in 13 patients (4%): 6 (2%) had transient coronary spasm, 4 (1%) had diaphragmatic stimulation, and 3 (1%) had stinging pain at the skin electrode. Of the 10 cases with pacing failure, left ventricular pacing was successfully tested in 5 by introducing the coronary wire or another wire into the left ventricle. It yielded a threshold of 2-8 (3.2 +/- 2.7) mA. Therapeutic pacing for significant bradycardia was required in 7 patients (2%). It was successful in all. Coronary or left ventricular pacing appears to be a simple and reliable temporary measure. When there is no wire in the coronary artery or for diagnostic catheterization, left ventricular pacing can be done using the same setup and any type of guidewire.

[Intracoronary electrocardiography during transluminal coronary angioplasty]. / Intrakoronares Elektrokardiogramm während transluminaler Koronarangioplastie.

To continuously record an intracoronary ECG during the crucial phase of percutaneous transluminal coronary angioplasty, the coronary guide wire was connected to an ECG recorder. In 25 patients the intracoronary ECG was recorded simultaneously with standard leads I, II and III during balloon occlusion of a coronary artery for 30-60 sec. The wire serving as electrode was positioned in the distal third of the coronary artery to be dilated, thus reflecting changes in the pertinent area of the myocardium. This was the left anterior descending coronary artery in 19 patients, the left circumflex coronary artery in 4 patients, and the right coronary artery in 2 patients. Electrocardiographic signs of ischemia were observed in 16 patients (62%). They were present in both the intracoronary ECG and at least 1 of the standard leads I, II or III in 11 patients, in the intracoronary ECG exclusively in 4 patients, and in the standard lead I exclusively in 1 patient. Sensitivity and specificity as an indicator for chest pain during balloon occlusion were 88% and 89% respectively for the intracoronary ECG and 63% and 78% respectively for the standard leads I, II and III. Sensitivity and specificity as an indicator for poor collateralization (coronary wedge pressure less than or equal to 25 mm Hg) were 100% and 69% respectively for the intracoronary ECG, and 60% and 62% respectively for the standard leads, I, II and III.(ABSTRACT TRUNCATED AT 250 WORDS)

[Emergency cardiac pacing via a coronary vessel during percutaneous coronary angioplasty]. / Stimulation cardiaque d'urgence par voie coronaire lors de l'angioplastie coronaire percutanée.

Percutaneous coronary angioplasty (PCA) is sometimes complicated by bradyarrhythmias necessitating emergency temporary cardiac pacing. This is usually performed by the classical transvenous endocardial approach. This experimental study investigated the possibility of using the metallic guide wire used during PCA as a monopolar electrode. Systematic electrical stimulation at different levels of the coronary arteries in 6 anaesthetised pigs showed threshold levels in the distal segments of 3 to 15 mA, close to the values observed in the right ventricule. Short periods of pacing were well tolerated. On the other hand, prolonged pacing (2 to 5 days) invariably led to the formation of a thrombus in the coronary segment occupied by the metallic guide wire and so should be avoided. This study shows that the metallic guide wire can be used as an emergency pacing electrode during PCA but this should be limited to a short period. This technique could replace the systematic introduction of classical transvenous pacing catheters.

Non-selective intra-arterial digital subtraction angiography for the assessment of coronary artery bypass grafts.

Non-selective intra-arterial digital subtraction angiography (DSA) was performed immediately before selective coronary and bypass angiography in 33 consecutive symptomatic patients 48 +/- 30 months after coronary surgery, for the assessment of 75 coronary bypass grafts. Forty ml of non-ionic, low-iodine content contrast medium (iohexol) were injected into the ascending aorta at 10-20 ml/sec through a 7 or 8 F femoral pigtail catheter. Electrocardiogram-triggered images were acquired on a Siemens Digitron II apparatus in multiple projections in 24 patients and in a single projection in 9 patients. The results of this technique were compared by two independent angiographers with those of selective graft angiography in the same patients. Patency was shown by DSA in 45 of 54 grafts confirmed to be open by selective angiography (sensitivity 83%). Of 21 occluded grafts, stumps were clearly visible at selective angiography in 18 and at DSA in 9 (sensitivity for graft stumps = 50%, p less than 0.01). Of 54 patent grafts with selective angiography, the distal anastomosis could be visualized by DSA in 28 (52%), but the resolution was comparable to selective angiography in 20 grafts (37%) only. A non-significant difference in the sensitivity of DSA was observed between patent saphenous grafts to the left anterior descending coronary artery versus all other coronary arteries (95 vs 85%, respectively), while only 1 of 5 patent left internal mammary artery grafts to the left anterior descending coronary artery was visualized. In 16 of 50 grafts (32%) visualized in a second projection substantial additional diagnostic information was obtained. In conclusion, non-selective intra-arterial electrocardiogram-triggered DSA can visualize patent saphenous grafts with a high sensitivity and may be a useful screening tool for bypass grafts patency; false negatives, however, and poor visualization of distal anastomoses limit its routine clinical use.

Damaging effect of therapeutic radiation on programmable pacemakers.

Two series of present-day pacemakers were tested in vitro with pulsed x-ray radiation. The first series of 12 pacemakers consisted of 10 different types and models of demand pacemakers (VVI). The second series of 13 pacemakers had 9 different types and models of programmable pacemakers. Unlike the first series which showed only mild changes in frequency and pulse width, all but four of the programmable pacemakers presented sudden complete failure after different radiation doses. We conclude that direct pulse radiation at therapeutic levels of programmable pacemakers should be avoided.